JVB Nameplate
  • Volume/Page
  • Keyword
  • DOI
  • Citation
  • Advanced
   
 
 
 
Search Issue | RSS Feeds RSS
Previous Issue

Nov 2003

Volume 21, Issue 6, pp. L9-3185

back to top
RSS Feeds

Synthesis of oxide nanoparticles embedded in polyimide

Yoon Chung, Hwan Pil Park, Hyung Jun Jeon, C. S. Yoon, Sung K. Lim, and Young-Ho Kim

J. Vac. Sci. Technol. B 21, L9 (2003); http://dx.doi.org/10.1116/1.1624269 (3 pages) | Cited 18 times

Online Publication Date: 7 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
© 2003 American Vacuum Society.
Show PACS
81.07.Bc Nanocrystalline materials
82.35.Np Nanoparticles in polymers
81.16.Be Chemical synthesis methods
61.46.-w Structure of nanoscale materials

Nanometer-period gratings in hydrogen silsesquioxane fabricated by electron beam lithography

Michael J. Word, Ilesanmi Adesida, and Paul R. Berger

J. Vac. Sci. Technol. B 21, L12 (2003); http://dx.doi.org/10.1116/1.1629711 (4 pages) | Cited 26 times

Online Publication Date: 18 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Hydrogen silsesquioxane (HSQ) is a high-resolution negative-tone inorganic resist for electron beam lithography. Investigations on the smoothness of the surfaces of thin films (less than 100 nm thick) have been conducted for nanolithography applications. It is demonstrated that films at thicknesses down to 25 nm have very low rms roughness and are defect free. Using 50 kV electron beam lithography, we demonstrate the achievement of isolated 6-nm-wide lines and 27 nm period gratings in 30 nm HSQ films on silicon substrates. These results are superior to those achieved with poly(methylmethacrylate) resist and demonstrates the versatility of HSQ for nanolithography. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
back to top
RSS Feeds

Atomic layer deposition of metal and nitride thin films: Current research efforts and applications for semiconductor device processing

H. Kim

J. Vac. Sci. Technol. B 21, 2231 (2003); http://dx.doi.org/10.1116/1.1622676 (31 pages) | Cited 122 times

Online Publication Date: 3 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Atomic layer deposition (ALD) has been studied for several decades now, but the interest in ALD of metal and nitride thin films has increased only recently, driven by the need for highly conformal nanoscale thin films in modern semiconductor device manufacturing technology. ALD is a very promising deposition technique with the ability to produce thin films with excellent conformality and compositional control with atomic scale dimensions. However, the applications of metals and nitrides ALD in semiconductor device processes require a deeper understanding about the underlying deposition process as well as the physical and electrical properties of the deposited films. This article reviews the current research efforts in ALD for metal and nitride films as well as their applications in modern semiconductor device fabrication. © 2003 American Vacuum Society.
Show PACS
01.30.Rr Surveys and tutorial papers; resource letters
68.55.-a Thin film structure and morphology
73.61.At Metal and metallic alloys
73.61.Ey III-V semiconductors
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy

Adhesion and stiction: Mechanisms, measurement techniques, and methods for reduction

Bharat Bhushan

J. Vac. Sci. Technol. B 21, 2262 (2003); http://dx.doi.org/10.1116/1.1627336 (35 pages) | Cited 100 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Solid–solid adhesion occurs at contacting asperities in two contacting solids. A thin liquid film with a small contact angle, present at the interface, can result in the so-called liquid-mediated adhesion. This may result in high adhesion during normal pull and high static friction during sliding, both commonly referred to as “stiction.” The problem of high stiction is especially important in an interface involving two very smooth surfaces under lightly loaded conditions. This article provides a critical and comprehensive review of mechanisms of adhesion and stiction, various measurement techniques, and methods used to reduce stiction in magnetic storage devices and micro/nanoelectromechanical systems. © 2003 American Vacuum Society.
Show PACS
62.20.Qp Friction, tribology, and hardness
81.40.Pq Friction, lubrication, and wear
68.35.Np Adhesion
68.35.Gy Mechanical properties; surface strains
46.55.+d Tribology and mechanical contacts
68.03.Cd Surface tension and related phenomena
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
back to top
RSS Feeds

Demonstrations of electronic pattern switching and 10× pattern demagnification in a maskless microion-beam reduction lithography system

V. V. Ngo, B. Akker, K. N. Leung, Isaac Noh, K. L. Scott, and S. Wilde

J. Vac. Sci. Technol. B 21, 2297 (2003); http://dx.doi.org/10.1116/1.1615978 (7 pages) | Cited 1 time

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A proof-of-principle ion projection lithography (IPL) system called maskless microion-beam reduction lithography (MMRL) has been developed and tested at the Lawrence Berkeley National Laboratory for future integrated circuits manufacturing and thin-film media patterning [V. V. Ngo et al., J. Vac. Sci. Technol. B 17, 6 (1999)]. This MMRL system is aimed at completely eliminating the first stage of the conventional IPL system [G. Stengl et al., J. Vac. Sci. Technol. B 10, 2824 (1992)] that contains the complicated beam optics design in front of the stencil mask and the mask itself. It consists of a multicusp rf plasma generator, a multibeamlet pattern generator, and an all-electrostatic ion optical column. Results from ion beam exposures on poly(methymethacrylate) and Shipley UVII-HS resists using 75 keV H+ are presented in this article. Proof-of-principle electronic pattern switching together with 10× reduction ion optics (using a pattern generator made of nine 50 μm switchable apertures) has been performed and is reported in this article. In addition, the fabrication of a microfabricated pattern generator [K. L. Scott et al., J. Vac. Sci. Technol. B 18, 6 (2000)] on a silicon on insulator membrane is also presented. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Critical dimension control of a plasma etch process by integrating feedforward and feedback run-to-run control

Chadi El Chemali, Jim Freudenberg, Matt Hankinson, Wenli Collison, and Tom Ni

J. Vac. Sci. Technol. B 21, 2304 (2003); http://dx.doi.org/10.1116/1.1615983 (9 pages) | Cited 2 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this article, we have derived a run-to-run (R2R) control design technique that integrates feedforward and feedback control on the etch process. The purpose is to minimize the effect of an oxygen flow disturbance during the resist trim on the polysilicon critical dimension (CD) after the main etch. The R2R controller manipulates the resist trim time based on feedforward measurements of the resist CD at the end of the lithography and feedback measurements from polysilicon CD at the end of the etch process. The purpose of the feedforward measurement is to adjust the resist trim time using a model of the relation between trim time, resist CD before the resist trim and polysilicon CD after the main etch. The purpose of the feedback measurement is to adjust this model to compensate for the oxygen flow disturbance during the resist trim. The resulting controller is called feedforward/feedback (FF/FB) controller. The FF/FB controller is tested using simulations and experiments conducted on an etch tool manufactured by Lam Research. The simulations and experimental results show that the FF/FB controller attenuates linear drift and shift in the polysilicon CD caused by the oxygen flow disturbance. Moreover, the results quantify the significant benefit of integrating feedforward and feedback control in addition to only using a feedforward control in minimizing the polysilicon CD deviations from the etch target. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning

Nanoparticle beam formation and investigation of gold nanostructured films

A. Khabari, F. K. Urban, P. Griffiths, I. Petrov, Y.-W. Kim, and C. Bungay

J. Vac. Sci. Technol. B 21, 2313 (2003); http://dx.doi.org/10.1116/1.1615985 (6 pages) | Cited 2 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The object of the present work is the formation of a nearly collimated beam of gold nanoparticles with a high deposition rate and investigation of the resulting nanostructured gold film deposited onto (111) silicon substrates. The shape, size, and orientation of nanostructured gold crystals were analyzed by transmission electron microscopy and x-ray diffraction, and optical properties were investigated by ellipsometry. It was found that the optical properties of gold nanostructured films are completely different from the optical properties of conventionally deposited films reported in the literature. It was also found most crystals were grown on (111) plane with an indication of an expitaxial contact between the film and the substrate. The crystallite size was approximately 8 nm in diameter. High-resolution transmission electron microscopy also revealed that the gold nanophase crystals are cubo-octahedral with larger surface areas (octahedral part) at (111) orientation. © 2003 American Vacuum Society.
Show PACS
68.55.-a Thin film structure and morphology
78.66.Bz Metals and metallic alloys
68.37.Lp Transmission electron microscopy (TEM)

Thermal stability of Pd supported on single crystalline SiO2 thin films

B. K. Min, A. K. Santra, and D. W. Goodman

J. Vac. Sci. Technol. B 21, 2319 (2003); http://dx.doi.org/10.1116/1.1617282 (5 pages) | Cited 11 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of annealing temperature on a model Pd/SiO2 catalyst has been investigated using Auger electron spectroscopy (AES) and scanning tunneling microscopy. Pd clusters on a single crystalline SiO2 thin film are not altered with respect to size or shape upon heating to 700 K; however, interdiffusion and sintering of the Pd clusters take place between 750 and 1050 K. At 1000 K, AES data imply the formation of Pd–silicide. Above 1050 K, desorption of Pd occurs concomitant with the decomposition of SiO2. © 2003 American Vacuum Society.
Show PACS
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
81.40.Gh Other heat and thermomechanical treatments
68.55.-a Thin film structure and morphology
68.35.Fx Diffusion; interface formation
61.72.Cc Kinetics of defect formation and annealing
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
68.43.Mn Adsorption kinetics

Photoluminescence quenching mechanisms in GaInNAs/GaAs quantum well grown by solid source molecular beam epitaxy

T. K. Ng, S. F. Yoon, W. J. Fan, W. K. Loke, S. Z. Wang, and S. T. Ng

J. Vac. Sci. Technol. B 21, 2324 (2003); http://dx.doi.org/10.1116/1.1617284 (5 pages) | Cited 8 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The photoluminescence (PL) quenching characteristics of a thermal-annealed ∼7 nm GaInNAs/GaAs quantum well (QW) with In=30% and N=1.5% were studied from 4 to 150 K. It is found that the integrated PL intensity versus temperature characteristic can be well fitted by a double activation energy model. One of the centers with low activation energy EB=9 meV is thought to originate from a localized state that traps carriers at temperatures below ∼100 K. Therefore, EB is the thermal energy required to activate the localized state carriers to the e1 state of the GaInNAs QW. Another center with larger activation energy EA=38 meV has a more significant PL quenching effect at temperatures above ∼120 K. This center is possibly contributed by the EL6 defect level in the GaAs barrier layer, as a result of low V/III ratio of 15, and low growth temperature of 450 °C. © 2003 American Vacuum Society.
Show PACS
78.67.De Quantum wells
78.55.Cr III-V semiconductors
73.21.Fg Quantum wells
61.72.Cc Kinetics of defect formation and annealing
73.20.Hb Impurity and defect levels; energy states of adsorbed species

Wavelet monitoring of plasma etching

Byungwhan Kim, Won Sun Choi, and Myo Teak Lim

J. Vac. Sci. Technol. B 21, 2329 (2003); http://dx.doi.org/10.1116/1.1617285 (5 pages) | Cited 1 time

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In device manufacturing sites, plasma states are conventionally monitored by measuring the etch rate. A means for plasma monitoring is presented. This was accomplished by characterizing profile variations by means of a discrete wavelet transformation (DWT). The sensitivity of wavelet coefficients was evaluated as a function of plasma faults, which were simulated with the variations in the process parameters, including radio frequency source power, bias power, and SF6 flow rate. For each plasma fault, wavelet sensitivity was conducted separately for vertical, lateral, and overall profiles. Wavelet coefficients demonstrated high sensitivity to detecting plasma faults. Improved sensitivity was obtained as they were monitored individually. Compared to conventional etch rate- or profile anisotropy-based sensitivity, the wavelet-based one was considerably enhanced. By the demonstrated high sensitivity, the proposed DWT-based profile monitoring can be effectively used to monitor and diagnose plasma processes. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning

Focused ion beam milling of diamond: Effects of H2O on yield, surface morphology and microstructure

D. P. Adams, M. J. Vasile, T. M. Mayer, and V. C. Hodges

J. Vac. Sci. Technol. B 21, 2334 (2003); http://dx.doi.org/10.1116/1.1619421 (10 pages) | Cited 26 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of H2O vapor introduced during focused ion beam (FIB) milling of diamond(100) are examined. In particular, we determine the yield, surface morphology, and microstructural damage that results from FIB sputtering and H2O-assisted FIB milling processes. Experiments involving 20 keV Ga+ bombardment to doses ∼1018 ions/cm2 are conducted at a number of fixed ion incidence angles, θ. For each θ selected, H2O-assisted ion milling shows an increased material removal rate compared with FIB sputtering (no gas assist). The amount by which the yield is enhanced depends on the angle of incidence with the largest difference occurring at θ=75°. Experiments that vary pixel dwell time from 3 μs to 20 ms while maintaining a fixed H2O gas pressure demonstrate the additional effect of beam scan rate on yield for gas-assisted processes. Different surface morphologies develop during ion bombardment depending on the angle of ion incidence and the presence/absence of H2O. In general, a single mode of ripples having a wave vector aligned with the projection of the ion beam vector forms for θ as high as 70°. H2O affects this morphology by lowering the ripple onset angle and decreasing the ripple wavelength. At high angles of incidence (θ>70°) a step/terrace morphology is observed. H2O-assisted milling at θ>70° results in a smoother stepped surface compared with FIB sputtering. Transmission electron microscopy shows that the amorphized thickness is reduced by 20% when using H2O-assisted FIB milling. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
68.35.B- Structure of clean surfaces (and surface reconstruction)
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.37.Lp Transmission electron microscopy (TEM)

Electric field effects in single semiconductor quantum dots observed by scanning tunneling luminescence

U. Håkanson, H. Håkanson, M. K.-J. Johansson, L. Samuelson, and M.-E. Pistol

J. Vac. Sci. Technol. B 21, 2344 (2003); http://dx.doi.org/10.1116/1.1620511 (4 pages) | Cited 3 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Scanning tunneling microscopy (STM) and scanning tunneling luminescence were used to correlate the topography with the emission spectra from individual self-assembled InP quantum dots (QDs). We have investigated in detail how the electric field induced by the STM tip affects the emission from the QDs. This was done when exciting a QD, by altering the bias for constant current, by altering the current for constant bias, or by changing the tip position. An increased bias (increased electric field) leads to Stark shift of the QD emission, whereas a larger tunneling current results in state filling of the emission. Furthermore, when exciting the QD, the position of the STM tip is shown to have large effects on the QD luminescence. © 2003 American Vacuum Society.
Show PACS
78.67.Hc Quantum dots
68.65.Hb Quantum dots (patterned in quantum wells)
73.21.La Quantum dots
78.55.Cr III-V semiconductors
68.37.Ef Scanning tunneling microscopy (including chemistry induced with STM)
78.60.Fi Electroluminescence
78.20.Jq Electro-optical effects

High aspect ratio nano-oxidation of silicon with noncontact atomic force microscopy

N. Clement, D. Tonneau, B. Gely, H. Dallaporta, V. Safarov, and J. Gautier

J. Vac. Sci. Technol. B 21, 2348 (2003); http://dx.doi.org/10.1116/1.1620513 (4 pages) | Cited 7 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the formation of high aspect ratio ∼0.3 (height/width) oxide features with noncontact mode atomic force microscopy assisted lithography. The process requires high humidity levels, series of short pulses <100 ns, high voltage level >25 V, a tip oscillation amplitude ∼20 nm, and feedback “on.” We also show that the application of a voltage at magnitude higher than a certain limit damages the surface. © 2003 American Vacuum Society.
Show PACS
81.16.Pr Micro- and nano-oxidation
81.65.Mq Oxidation
81.16.Ta Atom manipulation
81.16.Nd Micro- and nanolithography
68.37.Ps Atomic force microscopy (AFM)
85.40.Hp Lithography, masks and pattern transfer

20 nm polysilicon gate patterning and application in 36 nm complementary metal–oxide–semiconductor devices

Qiuxia Xu, Qian He, Ming Liu, Yuying Zhao, Baoqing Chen, Zhengsheng Han, Tianchun Ye, and Dexin Wu

J. Vac. Sci. Technol. B 21, 2352 (2003); http://dx.doi.org/10.1116/1.1620514 (8 pages) | Cited 4 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Plasma etching with high selectivity and anisotropy for 20 nm poly-Si gate patterning on EOT of 1.4 nm gate oxynitride is developed in a Cl2/HBr/O2 gas mixture successfully. Direct write e-beam lithography is used for an SAL601 chemically amplified negative resist pattern. Using a combination of resist ashing and TEOS hard mask trimming process, sub-25 nm TEOS SiO2 mask patterns are obtained in the control. Various gas mixtures based on Cl2, HBr, and O2 have been used to study the etching characteristics of poly-Si on EOT of 1.4 nm gate oxynitride. The O2 content as well as HBr are very sensitive to etch rate, selectivity, and the protection of the sidewalls of polysilicon, owing to SiO2-like film, SiOxBry, formed on the etched surface confirmed by x-ray photoelectron spectroscopy. And the ratio of Cl2/HBr/O2 in gas mixture is also tightly related to the etching profile. Using a four-step etching process under optimum conditions the selectivity of poly-Si to oxide is much higher than 500:1, in fact, after polysilicon etching the net deposition of oxide is observed, and no damage on the active area beside the gates for EOT of 1.4 nm gate oxide is observed, too. The etching profile of the 20 nm poly-Si gate pattern is perfectly vertical and an overall narrowing by an estimated 5 nm is observed for oxide masked poly-Si gate etching. The possible mechanism is discussed. This etching process combined with resist ashing and the TEOS hard mask trimming process are implemented successfully to the fabrication of high performance 36 nm gate length complementary metal–oxide–semiconductor (CMOS) devices and 42 nm gate length 32 frequency dividers with 57 stage/201 stage CMOS ring oscillators embedded, the EOT of gate oxynitrid is 1.4 nm, and very good results are obtained. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
81.16.Rf Micro- and nanoscale pattern formation
81.05.Cy Elemental semiconductors
81.65.Cf Surface cleaning, etching, patterning
79.60.Jv Interfaces; heterostructures; nanostructures

Switching characteristics of electrostatically actuated miniaturized micromechanical metallic cantilevers

W. H. Teh, J. K. Luo, M. R. Graham, A. Pavlov, and C. G. Smith

J. Vac. Sci. Technol. B 21, 2360 (2003); http://dx.doi.org/10.1116/1.1620515 (8 pages) | Cited 1 time

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the fabrication and characterization of the smallest near-curvature-free electrostatically actuated Ni micromechanical switches reported to date. Our smallest one, which measures 10.0 μm×4.0 μm×0.15 μm suspended over a 430 nm gap is realized by using electron beam cross-linked polymethylmethacrylate as the sacrificial layer and electroplated nickel as the main structural material. Tunnel barriers are defined via in situ formation of Al2O3 during the oxygen plasma dry release step with a metal–insulator–metal junction formed when the switch closes. The reliable curvature-free properties of these devices demonstrate low pull-in voltage drifts (<1.5 V), even after 1 billion switching cycles. Also, they did not reveal an appreciable physical change even after being subjected to sintering treatments of 450 °C for 30 min, making them promising candidates for encapsulations. These devices have low hysteretic switching behavior (∼0.5–4.5 V), as compared with similarly fabricated switches without the barrier, which remain stuck once turned on. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
73.40.Rw Metal-insulator-metal structures

Magnesium oxide gate dielectrics grown on GaN using an electron cyclotron resonance plasma

B. P. Gila, A. H. Onstine, J. Kim, K. K. Allums, F. Ren, C. R. Abernathy, and S. J. Pearton

J. Vac. Sci. Technol. B 21, 2368 (2003); http://dx.doi.org/10.1116/1.1620516 (3 pages) | Cited 7 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Magnesium oxide was grown by gas source molecular beam epitaxy on (0001) oriented metalorganic chemical vapor deposition n-GaN using elemental Mg and atomic oxygen supplied from an electron cyclotron resonance plasma source. X-ray diffraction (XRD) indicated that the oxide was single crystal for TSUB=350 °C and mostly polycrystalline for TSUB=100 °C. Reflection high energy electron diffraction suggests that the films deposited at the lower temperature begin with a single crystal nucleation layer then quickly become polycrystalline. For both growth temperatures, the magnesium oxide was highly textured toward the (111) direction, with the polycrystalline samples showing a broader XRD peak but smoother surfaces. Single crystal MgO grown at 350 °C had high current leakage, prohibiting electrical measurements. A breakdown field of 2.3 MV/cm and an interface state density of 4×1011 cm−2 eV−1 were measured for the polycrystalline (TSUB=100 °C) magnesium oxide/GaN heterostructure. © 2003 American Vacuum Society.
Show PACS
68.55.-a Thin film structure and morphology
77.84.Bw Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
52.77.Dq Plasma-based ion implantation and deposition
68.55.A- Nucleation and growth
77.22.Jp Dielectric breakdown and space-charge effects
73.20.-r Electron states at surfaces and interfaces
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)

Generation mechanism of residual clamping force in a bipolar electrostatic chuck

S. Kanno and T. Usui

J. Vac. Sci. Technol. B 21, 2371 (2003); http://dx.doi.org/10.1116/1.1620517 (7 pages) | Cited 2 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Clamping and residual clamping forces of a Johnsen–Rahbek-type (JR-type) bipolar electrostatic chuck (ESC), which has electrically independent dual electrodes, were measured. Area ratios of the ESC’s two electrodes ranged from 1 to 4.6. It was found that the clamping force per unit area decreases with increasing area ratio and that the residual clamping force per unit area increases with increasing area ratio. To reveal the mechanism of residual clamping force, an equivalent circuit model of a JR-type bipolar ESC was devised. The model showed that the residual clamping force is caused by the residual charge that results from the charge difference in two monopolar ESCs. The charge difference is due to the resistance dependency on voltage of the dielectric layer of the ESC. The wafer voltage calculated from the model agreed well with the voltage measured by an electrostatic voltmeter. It can be concluded that the model is suitable for simulating the performance of a bipolar ESC. © 2003 American Vacuum Society.
Show PACS
41.20.Cv Electrostatics; Poisson and Laplace equations, boundary-value problems
85.30.-z Semiconductor devices
77.55.-g Dielectric thin films
84.30.Bv Circuit theory
07.05.Tp Computer modeling and simulation

Annealing temperature dependence of contact resistance and stablity for Ti/Al/Pt/Au ohmic contacts to bulk n-ZnO

K. Ip, K. H. Baik, Y. W. Heo, D. P. Norton, S. J. Pearton, J. R. LaRoche, B. Luo, F. Ren, and J. M. Zavada

J. Vac. Sci. Technol. B 21, 2378 (2003); http://dx.doi.org/10.1116/1.1621651 (4 pages) | Cited 11 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
E-beam deposited Ti/Al/Pt/Au contacts on undoped (n∼1017 cm−3) bulk ZnO showed minimum specific contact resistance, ρc, of ∼6×10−4 Ω cm2 after annealing at 250 °C. This value was essentially independent of the surface cleaning procedure employed, including sequential solvent cleaning or H2 plasma exposure. Higher annealing temperatures degraded the ρc, and Auger electron spectroscopy depth profiling revealed increasing intermixing of the metal layers. The Al outdiffuses to the surface at temperatures as low as 350 °C, and the contact metallization is almost completely intermixed by 600 °C. © 2003 American Vacuum Society.
Show PACS
73.40.Cg Contact resistance, contact potential
73.40.Ns Metal-nonmetal contacts
61.72.Cc Kinetics of defect formation and annealing
68.35.Fx Diffusion; interface formation
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
61.72.S- Impurities in crystals
66.30.J- Diffusion of impurities

Electron field emission of radio frequency magnetron sputtered CNx films annealed at different temperatures

J. J. Li, W. T. Zheng, Z. S. Jin, X. Wang, H. J. Bian, G. R. Gu, Y. N. Zhao, S. H. Meng, X. D. He, and J. C. Han

J. Vac. Sci. Technol. B 21, 2382 (2003); http://dx.doi.org/10.1116/1.1621653 (6 pages) | Cited 7 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The carbon nitride films deposited by rf magnetron sputtering in a pure N2 discharge were annealed in vacuum up to 900 °C. The chemical composition and bonding structure of the films were studied using x-ray photoelectron spectroscopy, Raman spectroscopy, and Fourier transform infrared spectroscopy. It was found that the nitrogen atoms were bound to sp, sp2, and sp3 hybridized carbon atoms in as-deposited films. The effects of the thermal annealing on bonding structure and the electron field emission characteristics of CNx films were investigated. The results showed that thermal annealing treatment caused a great loss of N content and favor formation of sp2 bonds in CNx films, which would significantly influence the field emission properties for the CNx films. The CNx films annealed at temperature of 750 °C showed the optimal electron emission properties. Besides, the correlation between the chemical bonding structures and electron emission properties for the CNx films was discussed. © 2003 American Vacuum Society.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
81.15.Cd Deposition by sputtering
68.55.Nq Composition and phase identification
85.45.Db Field emitters and arrays, cold electron emitters
61.72.Cc Kinetics of defect formation and annealing
68.55.-a Thin film structure and morphology
79.60.Dp Adsorbed layers and thin films
78.30.Hv Other nonmetallic inorganics
78.66.Nk Insulators
82.80.Gk Analytical methods involving vibrational spectroscopy

Si adatom diffusion on Si (100) surface in selective epitaxial growth of Si

Seung-Hyun Lim, Sukchan Song, Tai-su Park, Euijoon Yoon, and Jong-Ho Lee

J. Vac. Sci. Technol. B 21, 2388 (2003); http://dx.doi.org/10.1116/1.1621656 (5 pages) | Cited 1 time

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The growth temperature dependence of Si adatom diffusion on Si (100) surface was systematically investigated in a cold wall ultrahigh vacuum chemical vapor deposition system. Si epitaxial layers were selectively grown on local oxidation of silicon patterned Si substrates. By cross-sectional transmission electron microscopy analysis, the increase in Si growth rate on the Si (100) surface near the edge of (311) facet was observed at various growth temperatures. This can be understood as a consequence of the mass transport from the sidewall (311) facet to the top (100) surface. Based on a simple diffusion model, the surface diffusion lengths of Si adatoms along the [110] direction were estimated to be about 70, 140, and 200 nm at 550, 600, and 650 °C, respectively. The calculated activation energy of 1.4 eV for diffusion of Si adatoms from the temperature dependence of the diffusion length was relatively higher than those in previous reports obtained under ultrahigh vacuum environment. This difference was discussed in terms of the discrepancy in the surface states by hydrogen adsorption on the Si surface. © 2003 American Vacuum Society.
Show PACS
68.43.Jk Diffusion of adsorbates, kinetics of coarsening and aggregation
68.35.Fx Diffusion; interface formation
68.55.A- Nucleation and growth
81.05.Cy Elemental semiconductors
73.20.Hb Impurity and defect levels; energy states of adsorbed species
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.47.Fg Semiconductor surfaces

Deep dry etching of GaAs and GaSb using Cl2/Ar plasma discharges

Alexander R. Giehl, Michael Gumbel, Matthias Kessler, Norbert Herhammer, Goetz Hoffmann, and Henning Fouckhardt

J. Vac. Sci. Technol. B 21, 2393 (2003); http://dx.doi.org/10.1116/1.1623507 (5 pages) | Cited 5 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Deep dry etch processes for GaAs and GaSb are investigated. Reactive ion etching in Cl2/Ar plasma discharges is used to pattern GaAs and GaSb with a single-layer soft mask resist. Soft masks have many advantages over (metal) hard masks such as easy and inexpensive processing, low pinhole density, and high etching reproducibility. Using TI35ES, an image reversal resist developed by MicroChemicals, GaAs etch profiles of up to 25 μm depth and GaSb structures of more that 50 μm depth are obtained revealing considerable dimensional stability. Even for etch durations of more than 50 min the resist can be easily removed from the sample surface after the etch process. Roughnesses of etched surfaces of less than 1 nm (rms, measured by atomic force microscopy) are obtained after reactive ion etching for both materials. Photoluminescence measurements reveal that the surface stoichiometry is conserved during the etching step. Deep dry etching of GaAs and GaSb can be exploited for example to fabricate fiber or capillary connections to and between optoelectronic devices or to create substrate windows for backside-illuminated photodetectors in the infrared wavelength range. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
81.05.Ea III-V semiconductors
52.77.Bn Etching and cleaning

Positive charge effect in atomic force microscope anodization lithography using self-assembled monolayers of metal phosphate as resists

Sang Min Kim and Haiwon Lee

J. Vac. Sci. Technol. B 21, 2398 (2003); http://dx.doi.org/10.1116/1.1623510 (6 pages) | Cited 9 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Various metal phosphate monolayers prepared as resists on silicon substrates were prepared for atomic force microscope (AFM) anodization lithography. The metal phosphate monolayers were prepared by binding tetravalent (Zr4+, Hf4+) or divalent (Ca2+, Mg2+) metal ions on a phosphorylated Si substrate. The presence of the metal ions on a phosphorylated Si substrate was confirmed using Auger electron spectroscopy. Since the divalent and tetravalent metal ions are changed to be neutral and divalent, respectively, after binding on phosphorylated substrates, the role of a positive ion in the monolayer structure in AFM anodization lithography was systematically investigated. The presence of positively charged metal ions in case of Zr4+ and Hf4+ enhances the electron transfer from a tip to a substrate under a tip negative bias. In addition to the effect of lowering a bias for anodization process, the lithographic scan speed was also enhanced by the order of magnitude in the presence of the positive ions. After patterning of protruding lines on Zr2+ phosphate monolayer, the etching process was also accomplished. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
81.16.Ta Atom manipulation
07.79.Lh Atomic force microscopes
81.16.Dn Self-assembly

Study of beveled angle effect on morphology of dual damascene via filling using ionized physical vapor deposition

Chi-Chuan Hwang, Jee-Gong Chang, Ming-Hang Weng, and Hong-Chang Lin

J. Vac. Sci. Technol. B 21, 2404 (2003); http://dx.doi.org/10.1116/1.1623511 (7 pages) | Cited 1 time

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article employs a molecular dynamics (MD) simulation approach to investigate the influence of beveled angles on the filling mechanisms of a dual damascene process. The objective of the present study is to propose a method that overcomes the problem of incomplete via filling associated with the traditional dual damascene process. The simulation incorporates three separate MD models, namely the dual via model, the deposition model, and the potential model. Furthermore, the simulation adopts the thermal control layer marching algorithm to increase the accuracy of the solution and to reduce the computational time. The present results indicate that the introduction of beveled angles at the upper via corners has a detrimental impact upon the filling of the lower via at moderately low via-radius ratios (1.75, 2.0). At a via-radius ratio of 1.75, the filling morphology changes from one of complete filling to one with trapped voids within the via when beveled angles are introduced, while at the slightly larger via-radius ratios of 2.0 and 2.5, the voids in the lower via are observed to grow in size. It is noted that the influence of beveled angles at the upper via corners on the lower via filling becomes less significant as the via-radius ratio increases (2.5, 3.0). In general, it is found that the introduction of beveled angles at the lower via corners is beneficial to the filling coverage of the lower via, but has no impact upon the filling of the upper via. © 2003 American Vacuum Society.
Show PACS
85.40.Ls Metallization, contacts, interconnects; device isolation
02.70.Ns Molecular dynamics and particle methods
85.40.Sz Deposition technology
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Formation of metastable c-AlN and its effect on the mechanical properties of AlN/(Ti,Al)N nanoscale multilayers

Xiaoping Hu, Xiaojiang Yu, Jijun Lao, Geyang Li, and Mingyuan Gu

J. Vac. Sci. Technol. B 21, 2411 (2003); http://dx.doi.org/10.1116/1.1624270 (4 pages) | Cited 2 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The formation of metastable phases has a great influence on the mechanical properties of multilayers. A series of AlN/(Ti,Al)N nanoscale multilayers with various modulation periods were synthesized by reactive magnetron sputtering. X-ray diffraction analysis, high resolution transmission microscopy and the microindentation technique were employed to characterize the microstructure and mechanical properties of the multilayers. The results show that metastable c-AlN forms due to the “template” effect of (Ti,Al)N in AlN/(Ti,Al)N multilayers with small modulation periods, and forms columnar crystals with (Ti,Al)N through epitaxial growth and results in lattice distortion due to the lattice mismatch between c-AlN and (Ti,Al)N. Correspondingly, the hardness and the elastic modulus of the multilayers increase with a decrease of modulation period monotonically and reach the maximal hardness (29 GPa) and elastic modulus (377.8 GPa) at a modulation period of 1.3 nm. © 2003 American Vacuum Society.
Show PACS
68.65.Ac Multilayers
68.35.Gy Mechanical properties; surface strains
62.20.Qp Friction, tribology, and hardness
62.20.D- Elasticity
81.15.Cd Deposition by sputtering

Growth of semiconductor gallium nitride nanowires with different catalysts

Jun Zhang and Lide Zhang

J. Vac. Sci. Technol. B 21, 2415 (2003); http://dx.doi.org/10.1116/1.1625968 (5 pages) | Cited 10 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Semiconductor gallium nitride nanowires had been prepared by different catalysts using chemical vapor deposition. In, Fe, Ni, and Au nanoparticles were used in the growth of semiconductor GaN nanowires. Preliminary results indicate that the In, Fe, and Ni are efficient catalysts in the large-scale synthesis of GaN nanowires and the size of the nanowires depends on the size of catalyst particle. The nanowires have a diameter of 20–100 nm and a length of up to several hundreds of micrometers. The growth of GaN nanowires obeys the vapor–liquid–solid mechanism. However, no GaN nanowires were observed on the substrate when Au was used. It may be because of the poor solubility between Au and nitrogen. Au does not have any catalytic activity in this system. © 2003 American Vacuum Society.
Show PACS
81.16.Hc Catalytic methods
81.07.Bc Nanocrystalline materials
82.33.Ya Chemistry of MOCVD and other vapor deposition methods
61.46.-w Structure of nanoscale materials
81.05.Ea III-V semiconductors
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Ion-enhanced chemical etching of HfO2 for integration in metal–oxide–semiconductor field effect transistors

Lin Sha, Ragesh Puthenkovilakam, You-Sheng Lin, and Jane P. Chang

J. Vac. Sci. Technol. B 21, 2420 (2003); http://dx.doi.org/10.1116/1.1627333 (8 pages) | Cited 40 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High-density chlorine plasmas were used to chemically etch HfO2, a promising high dielectric constant material, where the etch rate scaled up linearly with the square root of ion energy at energies above 50 eV. Higher etch rates were obtained at lower pressures and high microwave powers, where the electron temperature and ion densities were high. Optical emission spectroscopy and quadrupole mass spectrometry were used to identify the etching products, which are mainly highly chlorinated hafnium (HfCl3 and HfCl4) and ClO. Surface chlorination was confirmed after etching was confirmed by x-ray photoelectron spectroscopy. The addition of BCl3 in the Cl2 plasmas was found to significantly enhance the HfO2 etch rate and improve the etching selectivity to Si from ∼0.01 in a pure Cl2 plasma to ∼0.9 in a pure BCl3 plasma at an ion energy of 75 eV. The etching selectivity was improved to 4 as the ion energies reduced towards the etching threshold energy in a pure BCl3 plasma. BCl3 plasmas were found effective in patterning HfO2 for fabricating the metal–oxide–semiconductor field effect transistors, enabling a complete removal of HfO2 from the source and drain regions yielding high electron mobility. © 2003 American Vacuum Society.
Show PACS
52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
85.30.Tv Field effect devices
77.55.-g Dielectric thin films

Thickness effects on properties of GaInNAs quantum dots grown by molecular-beam epitaxy with nitrogen plasma source

K. C. Yew, S. F. Yoon, and Z. Z. Sun

J. Vac. Sci. Technol. B 21, 2428 (2003); http://dx.doi.org/10.1116/1.1627335 (4 pages) | Cited 2 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Self-assembled GaInNAs quantum dots (QDs) were grown on a GaAs (001) substrate by solid-source molecular-beam epitaxy equipped with a radio-frequency nitrogen plasma source. The GaInNAs QD growth characteristics were investigated using atomic-force microscopy (AFM) and photoluminescence (PL) measurements. The growth experiment was conducted using indium and nitrogen compositions of 50% and ∼1%, respectively, at different nominal thicknesses of 3 monolayers (MLs) to 6 MLs. AFM images suggest the onset of QD formation at ∼3 MLs and QD coalescence at ∼6 MLs. The highest PL intensity at low temperature (5 K) was obtained from the sample with nominal thickness of 5 ML, consistent with the highest QD density observed from AFM measurement. Under the present experimental conditions, GaIn0.5N0.01As QDs of 5–6 MLs gave the best optical property in terms of the lowest full width at half maximum and highest PL intensity. The reduced barrier potential of a strain-compensated layer (SCL) of GaNAs inserted between the substrate and GaInNAs QD layer was able to extend the PL emission wavelength by more than 140 nm compared to the sample without the GaNAs SCL. © 2003 American Vacuum Society.
Show PACS
81.07.Ta Quantum dots
68.65.Hb Quantum dots (patterned in quantum wells)
81.15.Hi Molecular, atomic, ion, and chemical beam epitaxy
68.37.Ps Atomic force microscopy (AFM)
81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors
78.67.Hc Quantum dots

Etching mechanisms of low-k SiOCH and selectivity to SiCH and SiO2 in fluorocarbon based plasmas

N. Posseme, T. Chevolleau, O. Joubert, L. Vallier, and P. Mangiagalli

J. Vac. Sci. Technol. B 21, 2432 (2003); http://dx.doi.org/10.1116/1.1627337 (9 pages) | Cited 25 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This study is dedicated to an analysis of the etch mechanisms of SiOCH, SiO2 and SiCH in fluorocarbon plasmas. The etching of these materials is performed on blanket wafers in a magnetically enhanced reactive ion etcher reactor using fluorocarbon based chemistry (CF4/N2/Ar). After partial etching, the Fourier transform infrared spectroscopy and mercury probe measurement indicate that the remaining substrate of SiOCH is not altered by the reactive plasma. A decrease in the etch rate of SiOCH, SiO2 and SiCH is observed either with increasing Ar dilution or polymerizing gas addition as CH2F2 and C4F6. X-ray photoelectron spectroscopy analysis of the surface after partial etching shows that the thickness of the fluorocarbon layer formed at the film surface and its composition play a key role in controlling etch rate and selectivity of SiOCH, SiO2 and SiCH. The etch rate of these materials is getting lower when the fluorocarbon layer thickness increases and also when its fluorine concentration decreases. The fluorocarbon layer thickness and composition depend on the plasma chemistry but also on the concentration and nature of impurities (C and H) in the etched materials. Etch rates are presented and discussed with respect to plasma parameters and material composition in terms of etching mechanisms. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
78.30.Hv Other nonmetallic inorganics
79.60.Bm Clean metal, semiconductor, and insulator surfaces

Electrical properties of SiO2 films with embedded nanoparticles formed by SiH4/O2 chemical vapor deposition

R. M. Rassel, T. Kim, Z. Shen, S. A. Campbell, and P. H. McMurry

J. Vac. Sci. Technol. B 21, 2441 (2003); http://dx.doi.org/10.1116/1.1627795 (7 pages) | Cited 1 time

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article uses real-time particle measurements as well as physical, chemical, and electrical film measurements to report on the properties of films with embedded particles formed during low-pressure chemical vapor deposition of SiO2 from silane and oxygen. The depositions were carried out at pressures and temperatures ranging from 0.3 to 2.0 Torr and 200–800 °C, using an O2/SiH4 ratio of 20. Aerosol size distributions were measured using a particle beam mass spectrometer. The effects of these particles on film properties, such as stoichiometry, particle concentration, dielectric constant, and current–voltage characteristics are presented along with transmission electron microscopy images to support findings. In addition the charge retention properties of these particle-incorporated films are discussed. © 2003 American Vacuum Society.
Show PACS
73.61.Ng Insulators
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.Nq Composition and phase identification
77.22.Ch Permittivity (dielectric function)
68.55.-a Thin film structure and morphology
78.47.-p Spectroscopy of solid state dynamics
61.66.Bi Elemental solids
61.66.Dk Alloys
77.55.-g Dielectric thin films

Reduction of ultraviolet-radiation damage in SiO2 using pulse-time-modulated plasma and its application to charge coupled 44 device image sensor processes

Mitsuru Okigawa, Yasushi Ishikawa, and Seiji Samukawa

J. Vac. Sci. Technol. B 21, 2448 (2003); http://dx.doi.org/10.1116/1.1629712 (7 pages) | Cited 14 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF


See Also: Erratum

Show Abstract
We found that vacuum-ultra/violet (VUV) light emitted by plasmas causes dark current in charge coupled device (CCD) image sensors. When a CCD was irradiated with inductively coupled plasmas using helium (He), argon (Ar) or oxygen (O2) gas, the He plasma caused higher plasma-induced dark current in the CCD than the Ar or O2 plasmas. To investigate the influence of VUV radiation in He plasma, the plasma-induced electric current in SiO2 was measured using two types of on-wafer monitoring devices to separate the effects of He ions and He VUV radiation. One monitoring device has an aluminum filter that only allows He VUV 58.4 nm to pass through, and the other has no filter. We performed time-resolved-measurement experiments using the two types of devices in pulse-time-modulated He plasma (He-TM plasma). With the filter device, the decay of the VUV intensity after plasma off corresponded completely to the decay of the plasma-induced current curve. On the other hand, in the no-filter device, decay curve of the plasma-induced current coincided with that of the electron density in the plasma. In other words, the TM plasma does not reduce the ion-induced current, but can completely reduce the photoinduced current in SiO2. In the CCD image sensor we found that the TM plasma dramatically suppresses plasma-induced dark current. Consequently, the effect of TM plasma on the CCD dark current is due to the influence of reducing the photons in the plasma. © 2003 American Vacuum Society.
Show PACS
61.80.Ba Ultraviolet, visible, and infrared radiation effects (including laser radiation)
61.82.Ms Insulators
72.40.+w Photoconduction and photovoltaic effects
81.65.Cf Surface cleaning, etching, patterning
07.57.Kp Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
42.79.Pw Imaging detectors and sensors
85.60.Gz Photodetectors (including infrared and CCD detectors)
52.77.Bn Etching and cleaning
78.47.-p Spectroscopy of solid state dynamics

Etching of 4H–SiC in a NF3/CH4 inductively coupled plasma

Byungwhan Kim, Suk Yong Lee, and Byung Teak Lee

J. Vac. Sci. Technol. B 21, 2455 (2003); http://dx.doi.org/10.1116/1.1629715 (6 pages) | Cited 5 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this study, SiC was etched in a NF3/CH4 inductively coupled plasma. Process parameters and experimental ranges are radio frequency (rf) source power 700–900 W, bias power 50–150 W, pressure 6–12 mTorr, and NF3 percentage 20%–100%. The etch rate and profile angle were examined as a function of process parameters. For optimization, effects of various parameter combinations were investigated by means of a 24 full factorial experiment. Main effect analysis revealed that the etch rate is the most significantly affected by NF3 percentage. In contrast, the source power effect was the most insignificant for both etch rate and profile. For the dc bias less than about 385 V, the etch rate was strongly correlated to the dc bias induced by the source power. This correlation was observed for variations in other parameters. This reveals that the dc bias played an important role in determining the etch rate. For variations in NF3 percentage, both etch rate and profile angle behaved in a conflicting way. The highest etch rate optimized by the experimental design is 450 nm/min, obtained at 700 W source power, 150 W bias power, 12 mTorr, and 100% NF3 percentage. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning

Ab initio calculations of field emission from ultrathin Si(100) films

Y. Gohda and S. Watanabe

J. Vac. Sci. Technol. B 21, 2461 (2003); http://dx.doi.org/10.1116/1.1624266 (5 pages) | Cited 4 times

Online Publication Date: 24 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have analyzed field emission from ultrathin Si(100) films on a metal substrate by using ab initio density functional calculations incorporating scattering states. We have shown that the clean Si(100) film can screen an external electric field sufficiently due to metallic states of surface dangling bonds, and thus field emission from the clean silicon film is attributed to that from surface states. We have also analyzed effects of metal adsorption on field emission from Si(100) films. We have obtained a much larger emission current from the Si(100)2×2-Al surface at 0.5 monolayer coverage than that from clean silicon and aluminum surfaces. The minimum local barrier height clearly explains the difference between the Si(100)2×2-Al surface and the clean Al(100) surface, which cannot be explained from the small difference in the work function between the two surfaces. We have also found that the emission current further increases with a change in the atomic position of adsorbed aluminum addimers which causes both a decrease in the minimum local barrier height and an increase in the local density of states at a surface around the Fermi level. © 2003 American Vacuum Society.
Show PACS
79.70.+q Field emission, ionization, evaporation, and desorption
73.20.Hb Impurity and defect levels; energy states of adsorbed species
71.15.Mb Density functional theory, local density approximation, gradient and other corrections
73.30.+y Surface double layers, Schottky barriers, and work functions

Evaluation of the cleanliness of the ion-assisted Mo–Si deposition process for extreme ultraviolet lithography

Stefan P. Hau-Riege, Paul B. Mirkarimi, Christopher C. Walton, Victor Sperry, and Cindy Larson

J. Vac. Sci. Technol. B 21, 2466 (2003); http://dx.doi.org/10.1116/1.1615979 (5 pages) | Cited 2 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Particles are a serious concern in the fabrication of reticles for extreme ultraviolet lithography because they nucleate perturbations in the reflective multilayer film that can print in the lithographic image. We call these perturbations defects. It has been suggested that reticle substrates can be planarized and the high-spatial-frequency roughness of the multilayer film can be reduced by using an ion-assisted Mo–Si deposition process. In this article we discuss the cleanliness of this ion-assisted deposition process. Within one cleaning cycle, we improved the cleanliness of the deposition process without ion assist from 3–4 to 0.26 particles/cm2. Of these, 0.09 particles/cm2 are due to manual handling of the wafers. We found that in our experimental setup, the added particle density using a process with ion assist is more then six times larger than the added density without ion-assist, suggesting that further work is necessary to develop a clean ion-assisted deposition process. We characterized the chemical composition of some of the added particles and found that they contain Al, C, Fe, Mo, and Si. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Comparative hydrogen sensing performances of Pd– and Pt–InGaP metal–oxide–semiconductor Schottky diodes

Yan-Ying Tsai, Kun-Wei Lin, Huey-Ing Chen, Chun-Tsen Lu, Hung-Ming Chuang, Chun-Yuan Chen, and Wen-Chau Liu

J. Vac. Sci. Technol. B 21, 2471 (2003); http://dx.doi.org/10.1116/1.1615980 (7 pages) | Cited 5 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The hydrogen sensing performances of Pd– and Pt–InGaP metal–oxide–semiconductor (MOS) Schottky diodes are systematically studied and compared under different operating temperature. It is known that, from experimental results, the Pd–InGaP MOS Schottky diode exhibits higher hydrogen detecting capability at lower hydrogen concentration regimes. On the contrary, the MOS Schottky diode with Pt catalytic material shows better hydrogen detecting capability and higher operating temperature. It is believed that the refractory Pt metal is responsible for detecting high hydrogen concentration in air, especially at high operating temperature. Furthermore, the temperature dependence of equilibrium constants is investigated and reported. In order to study the steady-state reaction kinetics, the van’t Hoff equation is used to estimate the values of initial heat of adsorption for both devices. Based on the Temkin isotherm model, the experimental results and theoretical simulation of hydrogen coverage are also studied and compared. © 2003 American Vacuum Society.
Show PACS
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.30.Kk Junction diodes

Patterning of gold film on muscovite mica by using a helium-metastable atom beam and an octanethiol self-assembled monolayer

X. Ju, M. Kurahashi, T. Suzuki, and Y. Yamauchi

J. Vac. Sci. Technol. B 21, 2478 (2003); http://dx.doi.org/10.1116/1.1615981 (4 pages)

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using a helium-metastable atom beam and an octanethiol (OT) self-assembled monolayer (SAM), we carried out atom lithography to the gold film on muscovite mica having a flat surface. A large intact area and a clear pattern with a nanoscale width ∼80–100 nm of the etched step was obtained. The gold surface, as well as the surface of the mica substrate, was flat. From the analysis of the roughness, appreciable gold islands were not detected in the area exposed to the He∗ atom beam. This finding demonstrates that the OT SAMs on atomically flat surfaces can be used as a resist for exposure to metastable-atom beams. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
79.20.Rf Atomic, molecular, and ion beam impact and interactions with surfaces
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.55.-a Thin film structure and morphology

Mitigation of residual film stress deformation in multilayer microelectromechanical systems cantilever devices

Jeffrey S. Pulskamp, Alma Wickenden, Ronald Polcawich, Brett Piekarski, Madan Dubey, and Gabe Smith

J. Vac. Sci. Technol. B 21, 2482 (2003); http://dx.doi.org/10.1116/1.1615982 (5 pages) | Cited 18 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An approach to compensate for the residual thin film stress deformation of multilayer microelectromechanical systems (MEMS) devices is presented based upon analytical and numerical modeling and in-process thin film characterization. Thermal and intrinsic deposition stresses can lead to the warping of released MEMS structures. This detrimental phenomenon in many cases can prevent proper device operation. Ellispsometric and laser wafer bow measurements yield thickness and film stress values that are used to update the deflection model during device fabrication, allowing for the compensation of the fabrication process variability. The derivations of linear and nonlinear residual film stress induced deflection models are presented. These models are based upon Bernoulli–Euler beam theory and are thus restricted to the associated geometric constraints. The models are initially validated by comparison with surface micro-machined sol–gel lead–zirconate–titanate cantilever structures; with initial experimental results agreeing well with both. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Comparison of dry etching of AlGaAs and InGaP in a planar inductively coupled BCl3 plasma

I. K. Baek, W. T. Lim, J. W. Lee, M. H. Jeon, G. S. Cho, and S. J. Pearton

J. Vac. Sci. Technol. B 21, 2487 (2003); http://dx.doi.org/10.1116/1.1615984 (5 pages) | Cited 7 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied dry etching of AlGaAs and InGaP in a planar inductively coupled BCl3 plasma. The process parameters were planar ICP source power (0–500 W), reactive ion etching (RIE) chuck power (0–150 W), and chamber pressure (5–15 mTorr). The process results were characterized in terms of etch rate, surface morphology, and surface roughness. The planar inductively coupled BCl3 plasmas were also monitored with in situ optical emission spectroscopy (OES). BCl3 planar inductively coupled process (ICP) etching of AlGaAs showed very vertical sidewall, clean and smooth surface, while that of InGaP showed somewhat rough surface after etching. Etch rates of AlGaAs were generally higher than those of InGaP in the planar BCl3 ICP etching. It indicated that InClX byproducts had relatively low volatility during InGaP etching in the planar inductively BCl3 plasmas. Increase of ICP source power and RIE chuck power strongly raised etch rates of both AlGaAs and InGaP. That of pressure decreased etch rate of both materials. OES data showed that emission intensity of the planar BCl3 ICP was a strong function of ICP source power and chamber pressure, while it was almost independent of RIE chuck power. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
81.05.Ea III-V semiconductors

SiC/Si-dots multilayer structures formed by supersonic free jets of CH3SiH3 and Si3H8

Yoshifumi Ikoma, Ryota Ohtani, Nobuaki Matsui, and Teruaki Motooka

J. Vac. Sci. Technol. B 21, 2492 (2003); http://dx.doi.org/10.1116/1.1617280 (4 pages) | Cited 1 time

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the formation of multilayer structures of SiC/Si-dots on Si(100) by supersonic free jet chemical vapor deposition. CH3SiH3 and Si3H8 jets were used for SiC and Si-dots, respectively. The first epitaxial SiC layer with a thickness of ∼15 nm and polycrystalline Si-dots with a size of ∼100 nm were grown by the first CH3SiH3 and following Si3H8 jet exposures. When the CH3SiH3 and Si3H8 jets were directed onto the Si-dot surface, thin (∼5 nm) SiC layers and ∼50 nm Si-dots were grown and formed Si-dots/SiC/Si-dots/SiC/Si(100). By repeating these SiC and Si-dots growths, polycrystalline SiC/Si-dots multilayer was formed on Si(100). © 2003 American Vacuum Society.
Show PACS
68.65.Ac Multilayers

Fabrication of subwavelength surface structures combining self-assembled masking layer with plasma etching techniques

E. Oesterschulze, G. Georgiev, M. Müller-Wiegand, A. Georgieva, and K. Ludolph

J. Vac. Sci. Technol. B 21, 2496 (2003); http://dx.doi.org/10.1116/1.1617281 (4 pages) | Cited 1 time

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A lithography-free method for producing periodic and nonperiodic surface structures is presented. It combines self-assembly of masking particles with well established plasma etching techniques known from microelectromechanical system technology. The method is generally applicable to bulk as well as layered materials. In our experiments, layers of glass spheres of different diameter were assembled on the sample surface forming a mask against plasma etching. Silicon surface structures with periodicity of 500 nm and feature dimensions of 20 nm were produced in this way. Thermal oxidation of the so structured silicon substrate offers the capability to vary the fill factor of the periodic structure owing to volume expansion during oxidation but also to define silicon dioxide surface structures by selective plasma etching. Similar structures can be simply obtained structuring silicon dioxide layers on silicon. The method offers a simple route, e.g., for photonic crystal fabrication. © 2003 American Vacuum Society.
Show PACS
42.70.Qs Photonic bandgap materials
81.65.Mq Oxidation

Proton implantation effects on electrical and optical properties of undoped AlGaN with high Al mole fraction

A. Y. Polyakov, N. B. Smirnov, A. V. Govorkov, N. V. Pashkova, S. J. Pearton, J. M. Zavada, and R. G. Wilson

J. Vac. Sci. Technol. B 21, 2500 (2003); http://dx.doi.org/10.1116/1.1617283 (6 pages) | Cited 7 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electrical and optical properties of undoped n-AlGaN films with Al composition close to 40% were studied before and after implantation of various doses of 100 keV protons. In the virgin samples, the electrical properties were determined by deep donor defects with an energy level near 0.25 eV from the conduction band edge and a concentration of ∼1018 cm−3. Other deep centers present had energy levels of 0.12, 0.3, and 0.45 eV. The luminescence spectra were dominated by two defect bands near 2.3 and 3.6 eV. Proton implantation significantly decreased the concentration of major donors even at the lowest doses of 1012 cm−2. For higher doses the Fermi level became progressively deeper and the data indicated complexing of defects present in the sample with either primary radiation defects or/and hydrogen introduced by implantation. The effect of the proton implantation on the intensity of luminescence bands was complicated but overall the intensity of defect bands was increased with implantation. © 2003 American Vacuum Society.
Show PACS
61.80.Jh Ion radiation effects
78.66.Fd III-V semiconductors
73.61.Ey III-V semiconductors
61.82.Fk Semiconductors
71.55.Eq III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence

Effect of bismuth oxide as a buffer layer on metal–lanthanum-substituted bismuth titanate–insulator–semiconductor structures

Sang-Woo Kang and Shi-Woo Rhee

J. Vac. Sci. Technol. B 21, 2506 (2003); http://dx.doi.org/10.1116/1.1620512 (6 pages)

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated metal/ferroelectric/insulator/semiconductor (MFIS) structures with lanthanum-substituted bismuth titanate (BLT) as a ferroelectric layer and bismuth oxide as an insulating buffer layer between BLT and Si substrate. BLT films and Bi oxide films were prepared by the direct liquid injection metal organic chemical vapor deposition process. The morphology of the Bi oxide film was changed with the increase of its thickness and the annealing temperature. Bi oxide on silicon was converted into Bi silicate during annealing at 750 °C. The morphology of the BLT films deposited on Bi oxide depended on the morphology of the Bi oxide film and on the reaction with Bi oxide during the annealing process, which was confirmed by transmission electron microscopy and energy dispersive x-ray spectroscopy. The maximum memory window was 0.83 V at the sweep voltage of 5 V with the Bi oxide film annealed at 650 °C and with a thickness of 5 nm. With BLT/Bi oxide annealed at 750 °C, the window was decreased due to the reaction between the BLT film, Bi oxide film, and Si substrate, and the leakage current density was increased. By inserting the buffer layer, the MFIS structure had a lower leakage current density than metal/ferroelectric/semiconductor structure. © 2003 American Vacuum Society.
Show PACS
77.55.-g Dielectric thin films
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
85.50.Gk Non-volatile ferroelectric memories
77.80.-e Ferroelectricity and antiferroelectricity
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
61.72.Cc Kinetics of defect formation and annealing

Effects of substrate heating and biasing on nanostructural evolution of nonepitaxially grown TiN nanofilms

T. Q. Li, S. Noda, F. Okada, and H. Komiyama

J. Vac. Sci. Technol. B 21, 2512 (2003); http://dx.doi.org/10.1116/1.1621654 (5 pages) | Cited 4 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of substrate heating and substrate biasing on the initial stage of nonepitaxial heterogeneous growth of TiN on Si(111) was studied by using high-resolution transmission electron microscopy. Although TiN films deposited at room temperature (RT) undergo a transition from continuous amorphous films to polycrystalline films with three-dimensional grains when the film thickness is increased from ∼1 to 2 nm, crystallization occurred at a substrate temperature, Ts=570 K, even for film thicknesses less than 1 nm. Compared with growth at Ts=RT, at Ts=570 K, the initial lateral grain size was only slightly larger, and the grains tended to be spherical and discontinuous at higher film thickness. At a substrate bias voltage, Vb=−70 V, the grains were laterally larger and planar. At a film thickness of 50 nm, the films deposited at Vb=−70 V showed the thermodynamically favored (200) preferred orientation, whereas the films deposited at Ts=570 K showed (111) preferred orientation with a weak (200) peak. © 2003 American Vacuum Society.
Show PACS
68.55.A- Nucleation and growth
61.46.-w Structure of nanoscale materials
81.15.Cd Deposition by sputtering
85.40.Ls Metallization, contacts, interconnects; device isolation
68.37.Lp Transmission electron microscopy (TEM)

Measurement of semi-isolated polysilicon gate structure with the optical critical dimension technique

Deepak Shivaprasad, Jiangtao Hu, Milad Tabet, Ray Hoobler, David Mui, and Wei Liu

J. Vac. Sci. Technol. B 21, 2517 (2003); http://dx.doi.org/10.1116/1.1622946 (7 pages)

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The semiconductor road map predicts the production of sub-100 nm transistor gates that push further the limits of the size and speed posed by 180 nm gates that are currently in use. With this decrease in gate size, it has become extremely critical to measure these lines accurately using nondestructive techniques. The optical critical dimension (OCD) technique is emerging as one of the most promising CD measurement techniques for sub-0.1 μm device fabrication. Compared to CD scanning electron microscopy and X-SEM, OCD has several distinct advantages. It is nondestructive, has a fast turnaround time, is sensitive to sidewall profiles, and has sensitivity to sub-100 nm linewidths. It has been successfully used in important structures such as photoresist, shallow trench isolation, and polysilicon and tungsten silicide gates. In the OCD technique, a broadband polarized light beam is focused onto a grating at angle normal to the grating surface, and the spectrum of zeroth order reflection is measured. The spectrum contains the signature of the grating profile that is analyzed in real time using rigorous coupled wave analysis. Real time curve fitting algorithms, which do not require library generation, make the analysis simple and easy to extend to a variety of grating structures. Since the OCD technique is based on specular diffraction, a primary requirement for the OCD measurement target is to have periodical grating structures with a line to space ratio typically larger than 1:1. In this article, we report use of the OCD technique to measure polysilicon gate gratings with line to space ratios as large as 1:20. Polysilicon gate grating structures with critical dimensions of 30–40 nm were measured for line to space ratios of 1:10 and 1:20. In both cases, the measurement showed extreme sensitivity to the linewidth and detailed profile, without deterioration of the repeatability. This study has significantly extended the measurement range of the OCD technique and its application to isolated line measurements. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
85.30.De Semiconductor-device characterization, design, and modeling

Effects of temperature and HCl flow on the SiGe growth kinetics in reduced pressure–chemical vapor deposition

J. M. Hartmann, V. Loup, G. Rolland, and M. N. Séméria

J. Vac. Sci. Technol. B 21, 2524 (2003); http://dx.doi.org/10.1116/1.1623508 (6 pages) | Cited 9 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Using a reduced pressure chemical vapor deposition cluster tool, we have studied at 20 Torr the growth kinetics of SiGe using a dichlorosilane+germane+hydrochloric acid chemistry. Adding HCl leads at 700 °C to a significant increase in the germanium content x of SiGe layers. Adopting a x2/(1−x)=n(F(GeH4)/F(SiH2Cl2)) dependence of x on the F(GeH4)/F(SiH2Cl2) mass flow ratio, this translates into an n value linearly increasing with the HCl mass flow from n=0.66 (no HCl) up to n=2.24 (F(HCl)/F(H2)=0.00625). The SiGe growth rate increases strongly with an increasing GeH4 flow. This is attributed to an increased hydrogen desorption caused by the presence of Ge atoms on the growing surface that frees nucleation sites for the incoming Ge and Si atoms. Meanwhile, adding HCl leads to a strong, linear reduction of the SiGe growth rate with the HCl mass flow. As expected, the Ge concentration decreases significantly as the growth temperature increases from 650 to 750 °C. The associated n parameter depends exponentially on the reverse absolute temperature, with an “activation energy” of the order of −15 kcal mol−1. At the same time, the SiGe growth rate increases strongly as the growth temperature increases, with an activation energy dropping from 47 down to 12 kcal mol−1 as the Ge content in the film goes up (from 0% up to 27% at 700 °C). © 2003 American Vacuum Society.
Show PACS
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.Hd Other semiconductors
68.55.A- Nucleation and growth

Technique for preventing stiction and notching effect on silicon-on-insulator microstructure

J. Li, Q. X. Zhang, A. Q. Liu, W. L. Goh, and J. Ahn

J. Vac. Sci. Technol. B 21, 2530 (2003); http://dx.doi.org/10.1116/1.1623509 (10 pages) | Cited 15 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The notching (undercutting or footing) and stiction problem, which widely exists in silicon-on-insulator microstructure were resolved in this study regardless of the feature sizes, by the introduction of a spacer oxide thin film. In this modified process, the deep reactive ion etching was divided into several steps, where conformal plasma enhanced chemical vapor deposition oxide coating, and anisotropic oxide etch were employed to prevent the notching effect. Dry chemical release was also realized in this approach but the deep etching did not etch through the device layer. The notching or footing effect was exploited for attaining the lateral etching following the deployment of the anisotropic plasma etching of the inductively coupled plasma. This method was proven useful for both the uniform and nonuniform feature designs. To validate the proposed etching method, an optical switch was fabricated. The details and benefits of the proposed process and its extensions to more valuable and flexible design were all discussed in this article. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
73.40.Qv Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
52.77.Dq Plasma-based ion implantation and deposition
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)

Improved productivity on diamond-like carbon coating optical disk stamper

H. Y. Ueng and C. T. Guo

J. Vac. Sci. Technol. B 21, 2540 (2003); http://dx.doi.org/10.1116/1.1624271 (5 pages)

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on a proposed process for depositing a diamond-like carbon (DLC) film on the back surface of a submaster stamper after a nickel electroforming process. This process could keep friction low and improve the productivity of an optical disk. Hydrogenated amorphous carbon films were deposited from a mixture of argon and acetylene by electron cyclotron resonance-chemical vapor deposition at pressures of about 5–9×10−3 mbar. In order to improve the adhesion strength of DLC films, functionally gradient Ti/TiN/TiCN supporting mutilayers were deposited on the stampers. The structural characteristics of DLC films were investigated by Raman spectroscopy. The properties of a DLC film coating on a stamper are summarized as follows: microhardness (five times improved), roughness less than 4 nm, excellent adhesion of 65 N, and coefficients of friction less than 0.1. The characteristics of the back surface coated by DLC film were improved, and the productivity of an optical disk per stamper is estimated at about 1.7 times more than obtained. Finally, the DLC submaster stamper could be used to overcome the barrier and dramatically improve the economics and yield of increased productivity of polymer compact disks. © 2003 American Vacuum Society.
Show PACS
42.79.Vb Optical storage systems, optical disks
81.05.U- Carbon/carbon-based materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.35.Np Adhesion
68.55.-a Thin film structure and morphology
68.65.Ac Multilayers
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials
78.35.+c Brillouin and Rayleigh scattering; other light scattering
68.35.Gy Mechanical properties; surface strains
62.20.Qp Friction, tribology, and hardness
81.40.Pq Friction, lubrication, and wear
42.82.Cr Fabrication techniques; lithography, pattern transfer

Smooth surface glass etching by deep reactive ion etching with SF6 and Xe gases

Li Li, Takashi Abe, and Masayoshi Esashi

J. Vac. Sci. Technol. B 21, 2545 (2003); http://dx.doi.org/10.1116/1.1624272 (5 pages) | Cited 20 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article reports on a smooth surface glass etching using deep reactive ion etching with a mixture of sulfur hexafluoride (SF6) and xenon (Xe) gases. A surface roughness of 23 Å was achieved with SF6/Xe(=1/1) and 18 Å with SF6/Ar(=1/4) under a condition of −390 V self-bias voltage and 0.2 Pa pressure. The surface roughness in the order of several angstroms (5.9 Å) was obtained at a pressure of 0.1 Pa (SF6/Xe=1/1). The average surface roughness (Ra) after the etching by SF6/Xe gas was smaller than those after the etching with SF6 only or SF6/Ar at a same mole fraction of the inert gas to SF6+inert gas. Since heavy inert gas increases the physical sputtering effect, the addition of the heavy inert gas helps to remove contaminant residues remaining on the etched surface. The optimum condition of smooth glass etching with high etch selectivity (21) is a pressure of 0.2 Pa and a mole fraction of Xe to SF6 gas is 8 to 7. We also make an analysis of the relationship between the surface average roughness on the bottom and the etched depth. The average roughness of the etched surface was smooth not only for the bottom but also for the sidewalls. The average surface roughness of the sidewalls was about 16 nm for 50-μm-deep etching under the same optimum condition. This technology was applied to a deep etching of quartz crystal used for a mass sensor. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
68.35.B- Structure of clean surfaces (and surface reconstruction)

Diffusion barrier properties of very thin TaN with high nitrogen concentration

S. M. Rossnagel and H. Kim

J. Vac. Sci. Technol. B 21, 2550 (2003); http://dx.doi.org/10.1116/1.1625953 (5 pages) | Cited 15 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
TaN deposited by magnetron sputtering has application in semiconductor interconnect structures as a diffusion barrier and adhesion layer. TaN used in these applications has a hexagonal or cubic structure consistent with roughly 1:1 Ta:N levels, with a bulk resistivity of 300–500 μΩ cm and a diffusion barrier failure temperature for 5 nm films of around 650 °C (Ref. 1). The diffusion barrier failure temperature (for Si/TaN-barrier/Cu samples) is a strong function of nitrogen concentration in the TaN; at the highest N levels (equivalent to nearly Ta3N5), the failure temperature exceeded 900 °C. At intermediate compositions, the failure temperature was found to exceed 700 °C even for films as thin as 0.4 nm. This suggests an interfacial contribution to diffusion barrier effectiveness, in addition to conventional grain boundary or bulk interdiffusion resistance, which may dominate conventional grain boundary diffusion. © 2003 American Vacuum Society.
Show PACS
68.35.Fx Diffusion; interface formation
85.40.Ls Metallization, contacts, interconnects; device isolation
68.55.Nq Composition and phase identification
81.15.Cd Deposition by sputtering
66.30.Ny Chemical interdiffusion; diffusion barriers
85.40.Qx Microcircuit quality, noise, performance, and failure analysis
73.61.At Metal and metallic alloys

Investigation of InGaP/GaAs heterojunction bipolar transistor with doping graded base

Yen-Wei Chen, Wei-Chou Hsu, Rong-Tay Hsu, Yue-Huei Wu, Yeong-Jia Chen, and Yu-Shyan Lin

J. Vac. Sci. Technol. B 21, 2555 (2003); http://dx.doi.org/10.1116/1.1625954 (3 pages) | Cited 5 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An n-p-n InGaP/GaAs heterojunction bipolar transistor (HBT) using a graded base doping profile has been fabricated by low pressure metalorganic chemical vapor deposition. A current gain of 77 and a base sheet resistance of 251 Ω/sq are achieved in the graded-base HBT. Compared to the graded-base structure, the nongraded-base structure has a lower current gain (68) and a higher base sheet resistance (294 Ω/sq). Furthermore, the studied graded-base HBT device also shows better microwave characteristics. The measured unity current-gain cutoff frequency (fT) can be improved from 18 to 22 GHz. The functional dependences of current gain, base sheet resistance, and microwave characteristics on the base doping profile are attributed to the graded-doping enhanced built-in field across the base and higher base doping at the emitter edge. © 2003 American Vacuum Society.
Show PACS
85.30.Pq Bipolar transistors
85.40.Ry Impurity doping, diffusion and ion implantation technology
84.40.-x Radiowave and microwave (including millimeter wave) technology
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Deep level defects and doping in high Al mole fraction AlGaN

S. T. Bradley, S. H. Goss, L. J. Brillson, J. Hwang, and W. J. Schaff

J. Vac. Sci. Technol. B 21, 2558 (2003); http://dx.doi.org/10.1116/1.1627331 (6 pages) | Cited 20 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have used depth-dependent cathodoluminescence spectroscopy (CLS) and secondary ion mass spectrometry (SIMS) to investigate the nature of deep level defects and their effect on Si doping of high Al mole fraction (25%–100%) AlGaN. SIMS results provide correlations between AlGaN deep level emissions from CLS and elemental impurities distributed through the epitaxial bulk films. The highest Al mole fraction (xAl) samples exhibit deep level optical emissions that correlate with O and C impurities measured by SIMS. These O impurities appear to introduce donors at low and intermediate Al compositions versus deep levels in Al-rich alloys. The CLS energy onset of near band edge peak emissions track the b=1 theoretical band gap for 0⩽xAl⩽0.98 while their peak emissions deviate monotonically. Temperature-dependent CLS reveal an activation energy decrease of the near band edge emission intensity from 54 to 36 meV for xAl>∼0.80. The absence of free carriers for xAl>0.80 is consistent with Si donor compensation due to deep levels associated with oxygen. © 2003 American Vacuum Society.
Show PACS
71.55.Eq III-V semiconductors
78.66.Fd III-V semiconductors
78.60.Hk Cathodoluminescence, ionoluminescence
61.72.S- Impurities in crystals
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.

Vertically aligned carbon nanotubes grown by plasma enhanced chemical vapor deposition

Hideki Sato, Hitoshi Takegawa, and Yahachi Saito

J. Vac. Sci. Technol. B 21, 2564 (2003); http://dx.doi.org/10.1116/1.1627332 (5 pages) | Cited 9 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Plasma enhanced chemical vapor deposition, which enables growth of carbon nanotubes directly onto substrates, is potentially suitable for preparing carbon nanotubes as electron sources in field emission displays. In this article, we report the growth of aligned carbon nanotubes by microwave plasma enhanced chemical vapor deposition and investigate the effect of various parameters on the growth. Comparison among three catalysts (Fe, Co, and Ni) revealed that Fe gives the longest carbon nanotubes, while Co gives the carbon nanotubes with the smallest diameter. The growth of the carbon nanotubes strongly depends on the treatment time in the plasma. Field emission characteristics from the carbon nanotubes grown by the microwave plasma enhanced chemical vapor deposition are also shown. © 2003 American Vacuum Society.
Show PACS
81.07.De Nanotubes
81.16.Hc Catalytic methods
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Dq Plasma-based ion implantation and deposition
61.46.-w Structure of nanoscale materials
79.70.+q Field emission, ionization, evaporation, and desorption
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces

Investigation of substrate rotation at glancing incidence on thin-film morphology

B. Dick, M. J. Brett, and T. Smy

J. Vac. Sci. Technol. B 21, 2569 (2003); http://dx.doi.org/10.1116/1.1627334 (7 pages) | Cited 22 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Films deposited by evaporation at glancing angles form structures dependent on the speed of substrate rotation. If the substrate is held stationary, oblique columns are grown. For slow substrate rotation, helices are formed while faster rotation yields pillars. Silicon and silicon dioxide films grown under similar conditions were found to follow the typical morphological trend. In contrast, aluminum films formed by glancing angle deposition (GLAD) were found to be facetted structures which were peaked and isolated at high rotation speeds (dφ/dt>42 rpm), and flat for dφ/dt∼1.5 rpm. The results suggest that the primary limiting factor controlling GLAD microstructure growth may be a combination of both material temperature and crystal structure of the resulting film. © 2003 American Vacuum Society.
Show PACS
68.55.-a Thin film structure and morphology
81.15.-z Methods of deposition of films and coatings; film growth and epitaxy
68.55.A- Nucleation and growth

Molybdenum/pure aluminum gate bus line defect reduction for high-resolution thin film transistor liquid crystal displays

Takatoshi Tsujimura and Atsuya Makita

J. Vac. Sci. Technol. B 21, 2576 (2003); http://dx.doi.org/10.1116/1.1629713 (8 pages) | Cited 2 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Defect mode analysis for pure aluminum was done to improve fabrication of very large high-resolution thin film transistor liquid crystal displays with very low gate line delay. Mouse hole defects in pure aluminum films are caused by the stress voiding due to the heating/cooling process and by vacancy diffusion. An oxygen treatment between the molybdenum and aluminum depositions is very effective in completely suppressing mouse hole formation. An additive material is also effective in suppressing mouse holes because of the reduction in grain size and the vacancy pinning. Blisters are created during heating processes and can be suppressed by using a MoTa/Mo/aluminum structure or by removal of the undercoat layer. © 2003 American Vacuum Society.
Show PACS
85.30.Tv Field effect devices
42.79.Kr Display devices, liquid-crystal devices
85.60.Pg Display systems
61.72.J- Point defects and defect clusters
66.30.Lw Diffusion of other defects

Structure, hardness, and elastic modulus of Pd/Ti nanostructured multilayer films

Junhua Xu, Masao Kamiko, Hidetaka Sawada, Yaomin Zhou, Ryoichi Yamamoto, Lihua Yu, and Isao Kojima

J. Vac. Sci. Technol. B 21, 2584 (2003); http://dx.doi.org/10.1116/1.1624267 (6 pages) | Cited 2 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The structure, hardness, and elastic modulus of Pd/Ti multilayers deposited by radio-frequency magnetron sputtering were investigated by x-ray diffraction, high-resolution transmission electron microscopy, and nanoindentation. Both the Ti and Pd layers were face-centered-cubic structures in all modulation periods from 2.8 nm to 90.0 nm in Pd/Ti multilayers. There are stacking faults in Ti layers at large modulation periods, where the crystal structure is hexagonal close packed. An anomalous hardness enhancement was observed. The hardness values of Pd/Ti multilayers are three times and two times the values measured in Pd films and as calculated by the rule of mixture for Pd and Ti films, respectively. The modulus values of Pd/Ti multilayers are between those of constituent single layer films at a larger modulation period, and increase slightly at a smaller modulation period. The elastic modulus difference model cannot explain this hardness enhancement, since the elastic modulus is almost the same for the constituent materials in the Pd/Ti multilayers. The hardening mechanisms in the multilayers have been discussed. © 2003 American Vacuum Society.
Show PACS
68.65.Ac Multilayers
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Jj Elasticity and anelasticity, stress-strain relations
61.72.Nn Stacking faults and other planar or extended defects
62.20.Qp Friction, tribology, and hardness
62.20.D- Elasticity
68.37.Lp Transmission electron microscopy (TEM)

Water-in-carbon dioxide microemulsions for removing post-etch residues from patterned porous low-k dielectrics

Xiaogang Zhang, Joseph Q. Pham, Hunter J. Martinez, P. Josh Wolf, Peter F. Green, and Keith P. Johnston

J. Vac. Sci. Technol. B 21, 2590 (2003); http://dx.doi.org/10.1116/1.1624268 (9 pages) | Cited 13 times

Online Publication Date: 25 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A hierarchy of CO2-based solvents is used to remove post-etch residues from vias and trenches in low-k patterned porous methylsilsesquioxane (pMSQ) interlayer dielectrics. Spectroscopic ellipsometry measurements indicate that, upon pressurization and depressurization with CO2, the thickness and refractive index return to values near the original values indicating that collapse or voiding of the pores did not occur. Post-etch residue could not be removed by pure water, CO2, with or without cosolvent, or dry CO2 with a surfactant. These results suggest that the particles could not be removed by a dissolution mechanism alone. The via and the bottom trench were cleaned with a solvent containing water, CO2, and a hydrocarbon surfactant. In this mild detergent system, particles may be removed both as a suspension and in the dissolved state in microemulsions and macroemulsions. The low interfacial tension prevents collapse of the pMSQ during water removal. This mild detergent system does not produce voids in the pMSQ. Thus, this detergent cleaning technique appears to be selective for post-ash residues on pMSQ dielectrics and is of significant practical interest. © 2003 American Vacuum Society.
Show PACS
81.65.Cf Surface cleaning, etching, patterning
back to top
RSS Feeds

Fabrication of nickel oxide nanostructures by atomic force microscope nano-oxidation and wet etching

Ju-Hung Hsu, Hsin-Wen Lai, Heh-Nan Lin, Chia-Chih Chuang, and Jin-Hua Huang

J. Vac. Sci. Technol. B 21, 2599 (2003); http://dx.doi.org/10.1116/1.1621655 (3 pages) | Cited 7 times

Online Publication Date: 26 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report the fabrication of nickel oxide nanostructures by atomic force microscope nano-oxidation and subsequent wet etching. By applying a negative bias to a conductive tip, nickel oxide patterns are first created by the process of nano-oxidation. The unoxidized nickel film is then etched away in a diluted nitric acid solution. Auger electron spectroscopy measurements confirm the complete removal of the nickel film and the preservation of the oxide patterns. Nickel oxide nanodots with diameters as small as 100 nm are reliably produced by the present method. © 2003 American Vacuum Society.
Show PACS
81.16.Pr Micro- and nano-oxidation
81.07.Ta Quantum dots
81.16.Rf Micro- and nanoscale pattern formation
81.65.Cf Surface cleaning, etching, patterning
68.37.Ps Atomic force microscopy (AFM)
68.65.Hb Quantum dots (patterned in quantum wells)
79.20.Fv Electron impact: Auger emission

n-type doping characteristics of O-implanted GaN

Yoshitaka Nakano, Tetsu Kachi, and Takashi Jimbo

J. Vac. Sci. Technol. B 21, 2602 (2003); http://dx.doi.org/10.1116/1.1621652 (3 pages) | Cited 2 times

Online Publication Date: 26 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Doping characteristics of O-implanted GaN have been investigated systematically from the viewpoint of annealing temperature. The implanted O atoms became electrically active as an n-type dopant after annealing above 1050 °C, but with a low activation efficiency of only 1.1%. From variable temperature Hall effect measurements, O-implanted GaN displayed a shallow ionization level of ∼18.3 meV after 1100 and 1200 °C anneals. In addition, secondary ion mass spectrometry measurements showed no measurable redistribution of the O atoms by the annealing. These results indicate poor probability of the O atoms occupying an N lattice site in GaN. © 2003 American Vacuum Society.
Show PACS
61.72.uj III-V and II-VI semiconductors
68.55.Ln Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Ey III-V semiconductors
71.55.Eq III-V semiconductors
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
81.05.Ea III-V semiconductors
61.72.Cc Kinetics of defect formation and annealing

Comments on “Analysis of the I–V characteristics of Al/4H-SiC Schottky diodes” by J. Zhang and W. R. Harrell [J. Vac. Sci. Technol. B 21, 872 (2003)]

Arthur D. van Rheenen

J. Vac. Sci. Technol. B 21, 2605 (2003); http://dx.doi.org/10.1116/1.1621658 (2 pages)

Online Publication Date: 26 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
© 2003 American Vacuum Society.
Show PACS
85.30.Hi Surface barrier, boundary, and point contact devices
73.30.+y Surface double layers, Schottky barriers, and work functions

Reply to: “Comments on ‘Analysis of the I–V characteristics of Al/4H–SiC Schottky diodes’ ”

J. Zhang and W. R. Harrell

J. Vac. Sci. Technol. B 21, 2607 (2003); http://dx.doi.org/10.1116/1.1621657 (1 page)

Online Publication Date: 26 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
© 2003 American Vacuum Society.
Show PACS
85.30.Hi Surface barrier, boundary, and point contact devices
73.30.+y Surface double layers, Schottky barriers, and work functions
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
back to top
RSS Feeds

Fabrication of an infrared antenna-coupled microbolometer linear array using chrome as a mask

Michael A. Gritz, Irina Puscasu, David Spencer, and Glenn D. Boreman

J. Vac. Sci. Technol. B 21, 2608 (2003); http://dx.doi.org/10.1116/1.1629714 (4 pages) | Cited 3 times

Online Publication Date: 26 November 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
© 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
84.40.Ba Antennas: theory, components and accessories
back to top
RSS Feeds
back to top Plenary Session: Disruptive and Off-Roadmap Technologies for Sub-25 nm Lithography

Imprint lithography for integrated circuit fabrication

D. J. Resnick, W. J. Dauksher, D. Mancini, K. J. Nordquist, T. C. Bailey, S. Johnson, N. Stacey, J. G. Ekerdt, C. G. Willson, S. V. Sreenivasan, and N. Schumaker

J. Vac. Sci. Technol. B 21, 2624 (2003); http://dx.doi.org/10.1116/1.1618238 (8 pages) | Cited 35 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The escalating cost for next generation lithography (NGL) tools is driven in part by the need for complex sources and optics. The cost for a single NGL tool could exceed $50M in the next few years, a prohibitive number for many companies. As a result, several researchers are looking at low cost alternative methods for printing sub-100 nm features. In the mid-1990’s, several research groups started investigating different methods for imprinting small features. Many of these methods, although very effective at printing small features across an entire wafer, are limited in their ability to do precise overlay. In 1999, Colburn et al. [Proc. SPIE 379 (1999)] discovered that imprinting could be done at low pressures and at room temperatures by using low viscosity UV curable monomers. The technology is typically referred to as step and flash imprint lithography. The use of a quartz template enabled the photocuring process to occur and also opened up the potential for optical alignment of the wafer and template. This article traces the development of nanoimprint lithography and addresses the issues that must be solved if this type of technology is to be applied to high-density silicon integrated circuitry. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Why optical lithography will live forever

Timothy A. Brunner

J. Vac. Sci. Technol. B 21, 2632 (2003); http://dx.doi.org/10.1116/1.1619954 (6 pages) | Cited 17 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A lithographic process capable of manufacturing state of the art chips faces many difficult challenges. Not only must the process resolve the minimum feature size but overlay errors must be held to tight tolerances, exquisitely complex patterns must be printed with high yield, and the overall cost of the process must be acceptable. Achieving acceptable chip cost using an expensive exposure tool is strongly linked to high throughput, and this in turn is linked to resist processes with high sensitivity. In recent years, chemically amplified resist processes have dominated state-of-the-art production because of their high resolution and excellent sensitivity. This article will consider limitations of resolution for production lithography, both the resolution limits of the exposure tool itself and the resolution limits of the resist process. Among the most important considerations for production processes is the tradeoff between resist process sensitivity and resolution. Fundamental reasons underlying the success of optical lithography for manufacturing integrated circuits will be described. These considerations will illuminate the challenges and opportunities for future lithographic methods. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
back to top Electron-Beam Lithography

Electron beam induced conductivity in poly(methylmethacrylate) and SiO2 thin films

Min Bai, R. Fabian W. Pease, and Dan Meisburger

J. Vac. Sci. Technol. B 21, 2638 (2003); http://dx.doi.org/10.1116/1.1618237 (7 pages) | Cited 1 time

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron beam charging and discharging of insulating samples is greatly influenced by electron beam induced conductivity (EBIC). Most prior studies on EBIC focused on inorganic materials; measuring EBIC in organic resist was hampered by high extrinsic leakage and low induced conductivity. We describe here EBIC in thin (1 μm) films of poly(methylmethacrylate) (PMMA) and thermal SiO2. The measurements were made using the external bias method, with the insulating thin film sandwiched between a metal electrode and a highly doped silicon substrate. Under the same exposure conditions, we found the induced conductivity in PMMA to be almost two orders of magnitude less than that in SiO2. The induced current in PMMA responds linearly to the bias, regardless of the polarity, but the induced current in SiO2 is surprisingly dependent on not only electron beam energy, but also on bias polarity. When the top metal electrode is biased positively and the electron beam has high enough energy to penetrate the electrode and the oxide, the results indicate that an internal emission of electrons from the silicon substrate into the oxide contributes substantially to the total measured current. © 2003 American Vacuum Society.
Show PACS
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)
73.61.Ng Insulators
73.61.Ph Polymers; organic compounds
61.80.Fe Electron and positron radiation effects
61.82.Ms Insulators
61.82.Pv Polymers, organic compounds

Complementary exposure of 70 nm SoC devices in electron projection lithography

Hiroshi Yamashita, Isao Amemiya, Kunio Takeuchi, Hideki Masaoka, Kimitoshi Takahashi, Akihiro Ikeda, Yukinori Kuroki, and Masaki Yamabe

J. Vac. Sci. Technol. B 21, 2645 (2003); http://dx.doi.org/10.1116/1.1622936 (5 pages) | Cited 4 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate complementary exposure of 70 nm system-on-a-chip (SoC) devices in electron projection lithography using Nikon’s EB stepper, NSR-EB1A, and a high-performance Si stencil mask (4×) fabricated by HOYA. A gate level of the SoC device pattern data called Anaheim was processed for mask fabrication using a 10 PC-clustered hierarchical data processing system in which complementary splitting was executed by the M-Split developed by Selete and ISS. Data processing times and output data volumes of the complementary split and of proximity effect correction were all drastically reduced by using our hierarchical data processing method. We optimized stitching features to compensate for the critical dimension (CD) changes that can occur with stitching errors caused by complementary exposures. The complementary stitching accuracy obtained was better than 20 nm and the CD accuracy was better than 10 nm for 100 nm line and space patterns because of the use of stitching features. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Nanometer-level stitching in raster-scanning electron-beam lithography using spatial-phase locking

J. T. Hastings, Feng Zhang, and Henry I. Smith

J. Vac. Sci. Technol. B 21, 2650 (2003); http://dx.doi.org/10.1116/1.1622944 (7 pages) | Cited 17 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Pattern-placement inaccuracy is a persistent problem in scanning-electron-beam lithography (SEBL) despite the high-resolution obtained in SEBL systems. Pattern-placement errors stem from a variety of environmental and system variations; however, the fundamental issue is the open-loop nature of the system, i.e., the beam location on the substrate is not monitored during exposure. In contrast, spatial-phase-locked electron-beam lithography (SPLEBL) provides closed-loop control of the beam position by monitoring the signal from a fiducial grid on the substrate. By detecting the spatial phase of the grid signal one can estimate the beam position within a small fraction of the grid period. We have implemented SPLEBL by adding real-time signal processing, feedback control, and raster-scan exposure capability to an inexpensive SEBL system. Using a 246 nm period, electron-transparent fiducial grid that covers the entire substrate, we have exposed patterns that exhibit global placement accuracy with respect to the grid and field-stitching precision better than 1.3 nm (one standard deviation). © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
81.16.Rf Micro- and nanoscale pattern formation

Wafer heating analysis for electron-beam projection lithography

J. Chang, G. F. Nellis, R. L. Engelstad, E. G. Lovell, and M. R. Sogard

J. Vac. Sci. Technol. B 21, 2657 (2003); http://dx.doi.org/10.1116/1.1625960 (6 pages) | Cited 1 time

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron projection lithography (EPL) is one of the principal next-generation lithography technologies for the sub-65 nm regime. To satisfy the stringent resolution requirements, all image placement errors must be characterized and minimized. These include the distortions of the device wafer during exposure. The wafer absorbs beam energy which produces temperature increases and thermomechanical strains that directly contribute to pattern-placement errors, stitching errors between adjacent subfields, and image blur. Thus, CD control and pattern overlay will be directly affected. In this article, the thermomechanical distortions caused by wafer heating in the EPL system have been simulated using finite element models that include the effects of the interaction between the wafer and chuck. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
44.05.+e Analytical and numerical techniques
02.70.Dh Finite-element and Galerkin methods

High-performance proximity effect correction for sub-70 nm design rule system on chip devices in 100 kV electron projection lithography

Kozo Ogino, Hiromi Hoshino, Yasuhide Machida, Morimi Osawa, Hiroshi Arimoto, Kimitoshi Takahashi, and Hiroshi Yamashita

J. Vac. Sci. Technol. B 21, 2663 (2003); http://dx.doi.org/10.1116/1.1625963 (5 pages)

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The proximity effect correction (PEC) system to achieve the practical processing time and data volume for sub-65 nm design-rule system on chip (SoC) devices is improved. The lump method, which is the technique to process several subfields at a time, is used to reduce the processing time for PEC. The hierarchical data processing for PEC is also proposed to reduce the data volume. A PC cluster system has been used to reduce the processing time for PEC. For an actual 70 nm design-rule SoC device data, the processing time has been reduced from 7.8 h to 10.3 min and the data volume has been reduced from 12.4 to 2.6 GB by using the lump method, the hierarchical data processing, and a ten PC cluster system. And, we have confirmed that the required critical dimension accuracy of ±5% is achieved for the device data in the simulation. We have successfully fabricated a full-size 8 in. Si stencil mask using the data with our PEC system for an actual 70 nm design-rule SoC device. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
84.30.Sk Pulse and digital circuits
85.40.Bh Computer-aided design of microcircuits; layout and modeling

Initial results of a 50 kV electron beam writer EBM-4000 for a 90 nm node photomask

Ken-ichi Murooka, Kiyoshi Hattori, and Osamu Iizuka

J. Vac. Sci. Technol. B 21, 2668 (2003); http://dx.doi.org/10.1116/1.1627803 (4 pages) | Cited 3 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed new 50 kV electron beam writer, EBM-4000, which is designed to fulfill the requirements for the 90 nm node mask. EBM-4000 makes use of the assets of our previous model, but major modifications are carried out on electron optics, writing circuits, and vacuum system. The written patterns are evaluated about CD uniformity, image placement accuracy, and throughput. The results indicate that CD uniformity and image placement accuracy meet the requirements for 90 nm node photomask, and EBM-4000 has a potential to extend its feasibility to 65 nm node photomask with acceptable throughput. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Dose control for fabrication of grayscale structures using a single step electron-beam lithographic process

Fei Hu and Soo-Young Lee

J. Vac. Sci. Technol. B 21, 2672 (2003); http://dx.doi.org/10.1116/1.1627808 (8 pages) | Cited 12 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Many optoelectronic devices include multidimensional (grayscale) semiconductor structures such as diffractive optical elements (DOE’s), blazed gratings, and photonic band gap (PBG) crystals. Their performance is known to be highly sensitive to dimensional accuracy of features in the multidimensional structure. Therefore, it is essential to have a tight control of the feature size in the fabrication process. Grayscale electron(e)-beam lithography enables a single step lithographic process for fabrication of such multidimensional structures and therefore has several advantages over using a binary lithographic process multiple times. As the feature size decreases, proximity effect in the e-beam lithographic process can make dimensions of the written features in a device substantially different from the ideal ones so that performance of the device is significantly degraded. In this paper, an efficient dose control scheme for grayscale e-beam lithography, which attempts to minimize the difference between the spatial exposure distribution and the “shape” of a multidimensional structure, is described along with results from an extensive computer simulation. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer

Correcting deviations in the shape of projected images in the electron beam block exposure column

Akio Yamada and Takayuki Yabe

J. Vac. Sci. Technol. B 21, 2680 (2003); http://dx.doi.org/10.1116/1.1627817 (6 pages) | Cited 6 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The block exposure column has a mask with one hundred stencils in a deflection area. Each mask pattern projected by electron beams is reduced in size to 1/60th and imaged onto a wafer. Deviations in image shapes are dependent on deflected beam trajectories and imaging beam currents. We show techniques to measure the image shapes using reflected electron signals. Correction methods are proposed to reduce the deviations. After the corrections, the block exposure can expose images of every mask pattern of the size 5×5 μm with the image size deviation less than 11 nm, which includes 5.8 nm of an isotropic expansion and 9.6 nm of distortions. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

First dynamic exposure results from an electron projection lithography tool

Kazuaki Suzuki, Tomoharu Fujiwara, Shinichi Kojima, Noriyuki Hirayanagi, Takehisa Yahiro, Jin Udagawa, Sumito Shimizu, Hajime Yamamoto, Motoko Suzuki, Hidekazu Takekoshi, Saori Fukui, Muneki Hamashima, Junji Ikeda, Teruaki Okino, Hiroyasu Shimizu, et al.

J. Vac. Sci. Technol. B 21, 2686 (2003); http://dx.doi.org/10.1116/1.1629287 (5 pages) | Cited 3 times

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron projection lithography (EPL) is one of the promising technologies below the 65 nm node, especially for contact hole and gate layers. Nikon is developing an EPL exposure tool as an electron beam (EB) stepper and the first generation EB stepper is now being manufactured. The voltage of 100 kV is adopted for electron beam acceleration. The subfield size is 0.25 mm×0.25 mm on the wafer and the deflection width of the electron beam is 5 mm on the wafer. The magnification of the projection optics is 1/4. A 5 mm×25 mm area from the ϕ200 mm reticle can be exposed by the combination of beam deflection and stage scanning motion (dynamic exposure). This area is called “a mechanical stripe.” After one mechanical stripe exposure, the reticle and wafer stages turn around and the next exposure of the adjacent mechanical stripe starts as a scan and stitch stage motion. Finally, a 20 mm×25 mm exposure field from the ϕ200 mm reticle is exposed. We report the first dynamic exposure in the history of EPL although only a ϕ100 mm reticle was used. A 5 mm×10 mm area was used as the mechanical stripe and 10 mm×10 mm exposure fields were exposed. 100 nm nested lines were resolved in the entire exposure field and stitching accuracies of 17–18 nm (3σ) are obtained. There remain systematic errors, and stitching accuracy less than 15 nm will be achieved after fine adjustment of the subfield positions. We feel the reality of EPL is now sufficiently proven. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Thermal analysis of projection electron beam lithography using complementary mask exposures

S. Babin, I. Kuzmin, H. Yamashita, and M. Yamabe

J. Vac. Sci. Technol. B 21, 2691 (2003); http://dx.doi.org/10.1116/1.1629293 (6 pages) | Cited 1 time

Online Publication Date: 4 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In projection electron beam lithography (EBL), most of the e-beam energy is deposited in the resist and substrate as heat. The temperature rise and its effect on critical dimension (CD) variation and placement error were studied at 100 kV projection EBL for exposure conditions used on a full scale production tool. A few writing strategies were considered. Analytic estimation of temperature rise was followed by numerical simulations using the temperature simulation software tool. Local temperature increases by a maximum of 10.7 °C was found at 5 μC/cm2 exposure dose, which corresponds to a few nanometers CD variation and can be over 10 nm depending on the resist and beam blur. Global substrate heating leads to a few tens of nanometers placement error that may suggest a need for better wafer cooling or active placement correction. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.70.Pg Thermal analysis, differential thermal analysis (DTA), differential thermogravimetric analysis
back to top Extreme-Ultraviolet Lithography

Printing-based performance analysis of the engineering test stand set-2 optic using a synchrotron exposure station with variable sigma

Patrick Naulleau, Kenneth A. Goldberg, Erik H. Anderson, Jeffrey Bokor, Bruce Harteneck, Keith Jackson, Deirdre Olynick, Farhad Salmassi, Sherry Baker, Paul Mirkarimi, Eberhard Spiller, Chris Walton, Donna O’Connell, Pei-Yang Yan, and Guojing Zhang

J. Vac. Sci. Technol. B 21, 2697 (2003); http://dx.doi.org/10.1116/1.1621669 (4 pages)

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
While interferometry is routinely used for the characterization and alignment of lithographic optics, the ultimate measure of performance for these optical systems is the transfer of an image or pattern into photoresist. Simple yet flexible exposure systems play an important role in this task because they allow complex system-dependent effects to be isolated from the printing results. One such tool has been implemented for alpha-class extreme ultraviolet (EUV) optics at Lawrence Berkeley National Laboratory using a synchrotron-based illumination source with programmable coherence. This static microfield exposure system has been used to characterize a four-mirror optical system designed for the EUV engineering test stand prototype stepper. Here we present a detailed performance analysis based on the large volume of lithographic data collected from this 0.1 NA system. Process window results are presented for dark field and bright field nested features down to a half pitch of 70 nm (k1 factor of 0.52) where a depth of focus of approximately 1 μm with 10% exposure latitude is demonstrated. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Effect of incident angle of off-axis illumination on pattern printability in extreme ultraviolet lithography

Minoru Sugawara, Akira Chiba, and Iwao Nishiyama

J. Vac. Sci. Technol. B 21, 2701 (2003); http://dx.doi.org/10.1116/1.1624264 (5 pages) | Cited 9 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effect of the incident angle of off-axis illumination on the printability of 22-nm-wide line patterns was investigated for three absorber stack configurations. Shadowing due to off-axis illumination and the absorber wall degrades printability, especially for a dense pattern layout. It was found that the influence of shadowing on resolution and pattern fidelity could be suppressed by employing a small incident angle and thin buffer and absorber films. An incident angle below 6.0° and an absorber stack with an optical density of 2.0 provide a practical level of pattern fidelity. Furthermore, a small incident angle below 5.0° and a thin absorber stack eliminate differences in fidelity for patterns with different orientations with respect to the direction of the off-axis light incident on a mask. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Preparations for extreme ultraviolet interferometry of the 0.3 numerical aperture Micro Exposure Tool optic

Kenneth A. Goldberg, Patrick P. Naulleau, Paul E. Denham, Senajith B. Rekawa, Keith H. Jackson, J. Alexander Liddle, Bruce Harteneck, Eric Gullikson, and Erik H. Anderson

J. Vac. Sci. Technol. B 21, 2706 (2003); http://dx.doi.org/10.1116/1.1627809 (5 pages) | Cited 2 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
An at-wavelength interferometer is being created for the measurement and alignment of the 0.3 numerical aperture Micro Exposure Tool (MET) projection optic at extreme ultraviolet (EUV) wavelengths. The prototype MET system promises to provide early learning from EUV lithographic imaging down to 20 nm feature size. The threefold increase to 0.3 NA in the image-side numerical aperture presents several challenges for the extension of ultrahigh-accuracy interferometry, including pinhole fabrication and the calibration and removal of systematic error sources. © 2003 American Vacuum Society.
Show PACS
07.60.Ly Interferometers
42.82.Cr Fabrication techniques; lithography, pattern transfer
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
back to top Ion-Beam Technology

Focused ion beam created periodic structures on tapered optical fibers

Vildana Hodzic, Jon Orloff, and Christopher Davis

J. Vac. Sci. Technol. B 21, 2711 (2003); http://dx.doi.org/10.1116/1.1621665 (4 pages)

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
High resolution focused ion beams have been used to create optical structures and to create high quality optical surfaces. We report here the use of Ga+ and B+ ion beams to produce gratings on optical fibers by micromachining and direct implantation, respectively. In both cases local periodic perturbations of the cladding refractive index were introduced in the reduced diameter (waist) region of biconically tapered single-mode optical fibers. By micromachining we produced short grooves perpendicular to the fiber axis and boron implantation gave a phase grating in the cladding. Both structures demonstrate a wavelength dependent throughput and are highly sensitive to the environment in the waist region, which makes them potentially applicable in sensors as well as in optical communication networks. © 2003 American Vacuum Society.
Show PACS
42.81.Wg Other fiber-optical devices
42.81.Bm Fabrication, cladding, and splicing
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Dj Gratings

Development of void-free focused ion beam-assisted metal deposition process for subhalf-micrometer high aspect ratio vias

Valery Ray, Nicholas Antoniou, Neil Bassom, Alex Krechmer, and Andrew Saxonis

J. Vac. Sci. Technol. B 21, 2715 (2003); http://dx.doi.org/10.1116/1.1621666 (5 pages) | Cited 4 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Low resistance metal deposition in deep submicron vias is required for circuit rewiring in focused ion beam (FIB)-based integrated circuit modification. Voids in high aspect ratio deposition, associated with the application of traditional FIB process to tungsten deposition in vias with aspect ratios beyond 10:1 contribute substantially to the resistance of the via. Pinch off of the via aperture is frequently observed. The dynamics of tungsten deposition within vias was studied through a series of via cross sections with variable deposition dose, and revealed accelerated deposition growth on the walls at the top of the vias. Accelerated deposition on the sidewalls, where the primary beam interacts with the substrate at a glancing angle, suggested that the deposition growth is initiated by secondary charged particles generated at the point of primary beam impact rather than by the primary beam itself. The results are in agreement with mechanisms previously proposed and confirmed by experiments. In order to prevent the generation of secondary particles on the walls of the via, and the consequent pinch off closure of the via aperture, confining the primary beam to an area much smaller than the aperture of the via was attempted. With this process, secondary particles are generated at the bottom of the via and trapped within the via, which was expected to lead to bottom-up deposition growth. A dose series study of the deposition produced by the proposed process confirmed the uniform growth of the tungsten fill from the bottom of the via. Void-free depositions were made in 5 μm deep vias ranging in size from 0.5 μm by 0.5 μm to 0.2 μm by 0.2 μm, corresponding to aspect ratios from 10:1 to 25:1, respectively. © 2003 American Vacuum Society.
Show PACS
85.40.Sz Deposition technology

Formation of a few nanometer wide holes in membranes with a dual beam focused ion beam system

T. Schenkel, V. Radmilovic, E. A. Stach, S.-J. Park, and A. Persaud

J. Vac. Sci. Technol. B 21, 2720 (2003); http://dx.doi.org/10.1116/1.1622935 (4 pages) | Cited 16 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
When nanometer-scale holes (diameters of 50 to a few hundred nm) are imaged in a scanning electron microscope (SEM) at pressures in the 10−5 to 10−6 Torr range, hydrocarbon deposits build up and result in the closing of holes within minutes of imaging. Additionally, electron or ion beam assisted deposition of material from a gas source allows the closing of holes with films of platinum or tetraethylorthosilicate oxide. In an instrument equipped both with a focused ion beam, and a SEM, holes can be formed and then covered with a thin film to form nanopores with controlled openings, ranging down to only a few nanometers, well below resolution limits of primary beams. © 2003 American Vacuum Society.
Show PACS
81.16.-c Methods of micro- and nanofabrication and processing
81.07.-b Nanoscale materials and structures: fabrication and characterization
61.46.-w Structure of nanoscale materials
61.82.Rx Nanocrystalline materials
61.80.Jh Ion radiation effects
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Resolution improvement for a maskless microion beam reduction lithography system

Ximan Jiang, Qing Ji, Lili Ji, Audrey Chang, and Ka-Ngo Leung

J. Vac. Sci. Technol. B 21, 2724 (2003); http://dx.doi.org/10.1116/1.1622937 (4 pages) | Cited 4 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A maskless ion projection lithography technique called maskless microion beam reduction lithography (MMRL) has been developed at Lawrence Berkeley National Laboratory. As a candidate for a next generation lithography system, MMRL is designed to achieve sub-70 nm resolution. By adding a 100 μm diam limiting aperture at the focal plane of the ion beam, an aperture angle of 0.56 mrad [corresponding to numerical aperture (NA)=5.6×10−4] at the image plane has been obtained. Small NA can decrease the geometrical and axial chromatic aberrations of the MMRL system. Thus resolution better than 150 nm has been obtained. Simulation results indicate that the resolution can be further improved by decreasing the aperture diameter and minimizing the limiting aperture induced aberrations. Meanwhile, the single-shot exposure time can still be as low as 193 ms at NA≈10−5 if the high brightness ion source design is employed in the MMRL system. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
41.85.Gy Chromatic and geometrical aberrations

Focused ion beam-induced fabrication of tungsten structures

M. Ishida, J. Fujita, T. Ichihashi, Y. Ochiai, T. Kaito, and S. Matsui

J. Vac. Sci. Technol. B 21, 2728 (2003); http://dx.doi.org/10.1116/1.1627806 (4 pages) | Cited 30 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Sidewall morphology on three-dimensional (3D) tungsten structures grown with focused ion beam-induced chemical vapor deposition (FIB-CVD) using tungsten hexacarbonyl [W(CO)6] was improved with a milling process by using FIB treatment subsequent to growth. As a result, Young’s modulus was measured at 300 GPa at maximum and density was measured at 13.0×103 kg/m3. Young’s modulus increased 35% after heat treatment at 600 °C in a vacuum while density did not change. Transmission electron microscopy revealed crystallization of tungsten trioxide after the heat treatment. © 2003 American Vacuum Society.
Show PACS
81.05.Bx Metals, semimetals, and alloys
68.60.Bs Mechanical and acoustical properties
68.55.-a Thin film structure and morphology
62.20.D- Elasticity
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.37.Lp Transmission electron microscopy (TEM)

Development of three-dimensional pattern-generating system for focused-ion-beam chemical-vapor deposition

T. Hoshino, K. Watanabe, R. Kometani, T. Morita, K. Kanda, Y. Haruyama, T. Kaito, J. Fujita, M. Ishida, Y. Ochiai, and S. Matsui

J. Vac. Sci. Technol. B 21, 2732 (2003); http://dx.doi.org/10.1116/1.1627812 (5 pages) | Cited 23 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We studied the fabrication of free-designed three-dimensional (3D) structures by using focused-ion-beam chemical-vapor deposition. The 3D structures are fabricated by scanning 30 keV Ga+ ion-beam-assisted deposition in a 1×10−4 Pa phenanthrene atmosphere. The scanning pattern and blanking signal of the ion beam are generated by a 3D computer-aided-designed model using a computer pattern-generating system. This 3D pattern-generating system is able to fabricate overhang and hollow structures by setting suitable parameters (for example, plot pitch, dwell time, time interval of irradiations, and priorities of scanning). In this article, we demonstrate the performance of a 3D pattern-generating system by fabricating a 1:100 000 000 scale model of the Enterprise spaceship, a microring, a moth’s eyelike structure, and a morpho butterflylike structure with 200 nm spacing. © 2003 American Vacuum Society.
Show PACS
81.16.Rf Micro- and nanoscale pattern formation

Free-space-wiring fabrication in nano-space by focused-ion-beam chemical vapor deposition

Takahiko Morita, Reo Kometani, Keiichiro Watanabe, Kazuhiro Kanda, Yuichi Haruyama, Takayuki Hoshino, Kazushige Kondo, Takashi Kaito, Toshinari Ichihashi, Jun-ichi Fujita, Masahiko Ishida, Yukinori Ochiai, Tsutomu Tajima, and Shinji Matsui

J. Vac. Sci. Technol. B 21, 2737 (2003); http://dx.doi.org/10.1116/1.1630329 (5 pages) | Cited 42 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Focused-ion-beam chemical vapor deposition (FIB-CVD) is an excellent technology for forming three-dimensional nanostructures. Various diamond-like-carbon (DLC) free-space-wirings have been demonstrated by FIB-CVD using a computer-controlled pattern generator, which is a commercially available pattern generator for electron-beam (EB) lithography. The material composition and crystal structure of DLC free-space-wiring were studied by transmission-electron microscopy and energy-dispersive x-ray spectroscopy. As a result, it became clear that DLC free-space-wiring is amorphous carbon containing a Ga core in the wire. Furthermore, the electrical resistivity measurement of DLC free-space-wiring was carried out by two terminal electrodes. Au electrodes were fabricated by EB lithography and a lift-off process. The electrical resistivity was about 100 Ω cm at room temperature. © 2003 American Vacuum Society.
Show PACS
81.07.Lk Nanocontacts
81.16.Nd Micro- and nanolithography
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
61.46.-w Structure of nanoscale materials
68.65.La Quantum wires (patterned in quantum wells)
73.63.Nm Quantum wires
81.05.U- Carbon/carbon-based materials
back to top Nanoimprint Lithography

Imprinting polymer film on patterned substrates

L. Tan, Y. P. Kong, L.-R. Bao, X. D. Huang, L. J. Guo, S. W. Pang, and A. F. Yee

J. Vac. Sci. Technol. B 21, 2742 (2003); http://dx.doi.org/10.1116/1.1624258 (7 pages) | Cited 14 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed a technique to create polymer film patterns on substrates with microstructures using an elastomeric polydimethylsiloxane (PDMS) pad, wherein either a continuous or a patterned film on flat PDMS was used for pattern creation. During patterning of the continuous film, a polymer film is first spin coated onto the elastomer pad, and the pad is then brought into contact with the patterned substrate of interest. Since the PDMS can deform elastically around features on the substrate and its surface has low interfacial energy, films on PDMS can be successfully transferred onto the substrate. The resulting profile of the transferred film would depend on the pattern dimensions of the substrate, polymer properties, and conditions for imprinting. Three distinctive film patterns can be achieved, which we designate as continuous film transfer over microstructures, film transfer on both trenches and protrusions, and film transfer on protrusions. Interestingly, a negative replica of patterns on substrates can be simultaneously created on the PDMS pad in the last patterning process and the pattern can be further utilized in subsequent patterning steps. This affords the capability of transferring a patterned film from the PDMS to the sidewalls of the topographic features. Because of the great versatility of this patterning technique, it can be used to rapidly form channels, conformal coating on a patterned substrate, and micro- or nanometer sized patterns inside trenches of a patterned substrate. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
85.40.Sz Deposition technology

Polymer inking as a micro- and nanopatterning technique

L.-R. Bao, L. Tan, X. D. Huang, Y. P. Kong, L. J. Guo, S. W. Pang, and A. F. Yee

J. Vac. Sci. Technol. B 21, 2749 (2003); http://dx.doi.org/10.1116/1.1625955 (6 pages) | Cited 11 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A polymer inking technique was developed to form micro- and nanopatterns on a substrate. In this process, a polymer thin film is spin coated on a patterned mold. After contacting the substrate at a suitable temperature and pressure, the polymer on the protruded surfaces of the mold is transferred to the substrate and a positive image of the mold is obtained. A selective surface treatment method has been developed to improve the edge smoothness of the inked pattern. During selective surface treatment, the protruded surfaces of the mold are first treated with a flat poly(dimethylsiloxane) stamp impregnated with a silane that has medium surface energy. The mold is then immersed into the solution of another silane with very low surface energy to treat the trenches of the mold. Because the surface energy of the sidewalls is lower than that on the protrusions, polymer dewetting from the sidewalls is promoted, which makes the polymer film discontinuous along the edges of patterns. Therefore, inked polymer patterns from the protrusions of the mold show very smooth edges and smaller dimensions compared to that of the mold. The dimension change of the inked pattern is dependent on the selection of polymer materials. It was found that patterns inked from poly(carbonate) showed larger dimension shrinkage (∼75%) compared to that from poly(methyl methacrylate) (∼30%). This offers a viable approach to obtain predictable submicrometer features using a mold with much larger feature sizes. © 2003 American Vacuum Society.
Show PACS
81.16.Rf Micro- and nanoscale pattern formation
68.47.Mn Polymer surfaces
81.10.Fq Growth from melts; zone melting and refining
68.35.Md Surface thermodynamics, surface energies
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
81.65.-b Surface treatments

Fabrication of sawtooth diffraction gratings using nanoimprint lithography

Chih-Hao Chang, R. K. Heilmann, R. C. Fleming, J. Carter, E. Murphy, M. L. Schattenburg, T. C. Bailey, J. G. Ekerdt, R. D. Frankel, and R. Voisin

J. Vac. Sci. Technol. B 21, 2755 (2003); http://dx.doi.org/10.1116/1.1627814 (5 pages) | Cited 10 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report a process which integrates interference lithography, nanoimprint lithography, and anisotropic etching to fabricate replicated diffraction gratings with sawtooth profiles. This new process greatly reduces grating fabrication time and cost, while preserving the groove shape and smoothness. Relief gratings with 400 nm period inverted triangular profiles and 200 nm period gratings with 7° blaze angle were replicated from silicon masters with surface roughness of less than 1 nm. This process was developed for fabricating the off-plane blazed diffraction gratings for the NASA Constellation-X x-ray telescope. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Dj Gratings

Large scale ultraviolet-based nanoimprint lithography

B. Vratzov, A. Fuchs, M. Lemme, W. Henschel, and H. Kurz

J. Vac. Sci. Technol. B 21, 2760 (2003); http://dx.doi.org/10.1116/1.1627816 (5 pages) | Cited 27 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Limits in resolution and accuracy of large scale ultraviolet (UV)-based nanoimprint lithography using rigid quartz molds and spin coated UV curable resists are presented. The resolution and precision parameters are closely followed from pattern in the mold through imprints in the resist and finally compared with structures transferred into silicon by special etching processes. Specific attention is paid to the simultaneous patterning of nano and microscale structures. The applicability for functional nanoelectronic components is demonstrated by the fabrication of an NMOS transistor based on SOI, whose channel width is reduced to 50 nm. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
85.30.Tv Field effect devices

Defect analysis in thermal nanoimprint lithography

Yoshihiko Hirai, Satoshi Yoshida, and Nobuyuki Takagi

J. Vac. Sci. Technol. B 21, 2765 (2003); http://dx.doi.org/10.1116/1.1629289 (6 pages) | Cited 44 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The fracture defect of the polymer in thermal nanoimprint lithography is studied based on numerical simulation and experiments. Hot pressing, cooling, and releasing steps in nanoimprint lithography are investigated in detail by a numerical simulation study. The applied pressure after the polymer deformation below the glass transition temperature will induce a stress concentration at the corner of the polymer pattern. On the other hand, the difference of the thermal expansion coefficients between the mold and the substrate causes lateral strain, and the strain is concentrated at the corner of the pattern. These strains induce defects and cause fracture defects at the base part of the pattern during the mold releasing step. To eliminate the defects, the applied pressure is released below the glass transition temperature, and slow cooling is introduced to relax the stress concentration. The result shows successful fabrication of fine patterns with a high aspect ratio. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Step and flash imprint lithography template characterization, from an etch perspective

W. J. Dauksher, D. P. Mancini, K. J. Nordquist, D. J. Resnick, D. L. Standfast, D. Convey, and Y. Wei

J. Vac. Sci. Technol. B 21, 2771 (2003); http://dx.doi.org/10.1116/1.1629299 (6 pages) | Cited 3 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
As a means of studying process windows with short turnaround time while avoiding substrate-to-substrate repeatability issues, Step and Flash Imprint Lithography templates were fabricated with physical masking of quadrants during dry etching used to introduce process perturbations. For every 20 s of descum (Ar/O2 etch) time, critical dimensions (CD) were observed to change approximately 2.6 nm on sub-100 nm features. Similarly, increasing Cr overetch time by 20% resulted in a positive CD change of 3.8 nm. Line edge roughness decreased with increasing descum and Cr overetch times. Best overall performance was observed for a 20 s descum used in conjunction with a 110% Cr overetch. Of four tip types studied, sharpened silicon atomic force microscopy tips were able to accurately measure etch depth of 80 nm trenches, but geometrical considerations limited sidewall angle determination to greater than 100°. Cross-sectioning of features on 6×6×0.25 in. quartz plates was successfully accomplished using a focused ion beam technique with typical sidewall angles of about 95° observed on 150 nm features. Finally, minimal microloading was observed for the ICP-based quartz etch process. Feature sizes ranging from 70 nm up to 8 μm possessed an average etch depth of 88.8 nm with a 1.2 nm (1 sigma) variation. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
42.82.Cr Fabrication techniques; lithography, pattern transfer
68.37.Ps Atomic force microscopy (AFM)
52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning

Study on optical intensity distribution in photocuring nanoimprint lithography

Yoshihiko Hirai, Hisao Kikuta, and Toshikazu Sanou

J. Vac. Sci. Technol. B 21, 2777 (2003); http://dx.doi.org/10.1116/1.1629717 (6 pages) | Cited 8 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Optical intensity distribution in photocuring nanoimprint lithography is investigated. Its dependency on pattern size, optical index, and residual thickness of the photopolymer has been numerically evaluated using the finite-difference time-domain method. The irradiated beam propagates mostly in the photopolymer, where the optical index is larger than that of the quartz mold. If the pattern size is less than around 1/4 wavelength of the irradiated beam, optical intensity in the polymer decreases because the light propagates through both the polymer and quartz molds. In addition, the index difference between mold and polymer increases diffraction into the residual layer and causes optical intensity concentration at a particular position. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
42.70.Ce Glasses, quartz
42.70.Jk Polymers and organics
42.82.Cr Fabrication techniques; lithography, pattern transfer
02.70.Bf Finite-difference methods

Nanoimprint lithography process optimization for the fabrication of high electron mobility transistors

D. S. Macintyre, Y. Chen, D. Gourlay, E. Boyd, D. Moran, X. Cao, K. Elgaid, C. R. Stanley, I. Thayne, and S. Thoms

J. Vac. Sci. Technol. B 21, 2783 (2003); http://dx.doi.org/10.1116/1.1629719 (5 pages) | Cited 5 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We previously reported a procedure for the fabrication of high electron mobility transistors (HEMTs) using nanoimprint lithography [Y. Chen et al., Microelectron. Eng. 67,68, 189 (2003)] to produce T-shaped gates with 120 nm foot widths. The most recent batch of transistors fabricated by this original procedure had a peak transconductance of 450 mS/mm and fT of 40 GHz. In this article we describe a number of refinements to the original process with the main aims to improve performance and yield of devices. The work had two parallel strands. The first involved the development of improved silicon stamping tools to limit resist trenching effects and to produce stamping tools with smaller foot widths. T-shaped tools with 50 nm foot widths were produced from this work. The second strand of work was to optimize various aspects of transistor design and the imprint conditions used to fabricate gates which resulted in pHEMTs with a peak transconductance of 480 mS/mm and an fT of 75 Ghz. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
85.30.Tv Field effect devices
back to top Optical Lithography

Simulating fluid flow characteristics during the scanning process for immersion lithography

A. Wei, A. Abdo, G. Nellis, R. Engelstad, J. Chang, E. Lovell, and W. Beckman

J. Vac. Sci. Technol. B 21, 2788 (2003); http://dx.doi.org/10.1116/1.1622939 (6 pages) | Cited 6 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Immersion lithography has been proposed as a method for improving optical lithography resolution to 50 nm. The premise behind the concept is to increase the index of refraction in the space between the lens and wafer by insertion of a high refractive index liquid in place of the low refractive index air that currently fills the gap. Because the liquid will act as a lens component during the lithographic process, it must maintain high uniform optical quality. One source of optical degradation may be due to changes in the liquid’s index of refraction caused by a change in temperature. During the exposure process, energy is deposited onto the wafer, causing a rise in temperature. Consequently, any liquid in direct contact with elevated temperature portions of the wafer will also experience an increase in temperature. Two-dimensional computational fluid dynamics models were created to assess the thermal and fluid effects of the exposure process on the liquid temperature. This article presents the results of the numerical thermal and flow simulations. Both aligned and opposing flow directions were investigated for a range of inlet pressures that is consistent with what can be expected with active filling jets. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
42.82.Cr Fabrication techniques; lithography, pattern transfer
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Extending optics to 50 nm and beyond with immersion lithography

M. Switkes, R. R. Kunz, M. Rothschild, R. F. Sinta, M. Yeung, and S.-Y. Baek

J. Vac. Sci. Technol. B 21, 2794 (2003); http://dx.doi.org/10.1116/1.1624257 (6 pages) | Cited 8 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Numerical imaging simulations demonstrate the capability of immersion lithography to print features smaller than 45 nm (35 nm) with good depth of focus at a vacuum wavelength of 193 nm (157 nm). The optical impact of index variation of the immersion liquid is simulated and found to be a shift of focus of 1 nm for each 1 ppm change in the bulk index of the liquid. For an index which varies through the thickness of the liquid (e.g., due to nonuniform temperature), the focus shift is found to be proportional to the total change in optical path length (OPL), with a 1 nm change in OPL leading to a ∼1.5 nm focus shift at 1.3 numerical aperture. A focus offset of 1–3 nm can be expected due to heating during scanning exposure. The possible formation of nanobubbles at resist surfaces is also discussed. While simulations show that even 10 nm thick bubbles at the surface of the resist cause 30% modulation in the aerial image intensity, no evidence of bubbles is seen in open frame immersion exposures. Imaging of 100 nm features is shown using an immersion contact phase-edge technique, with no evidence of bubbles or adverse liquid–resist interactions. Finally, we describe progress in the search for low absorbance liquids for use at 157 nm. Liquid purity, including dissolved O2 and H2O, is found to be critical. The current absorbance record, 0.64±0.07 cm−1, held by perfluorotriglyme (CF3[OCF2CF2]3OCF3), is enough for a 350 μm working distance at 95% transmission. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Linear phase ring illumination monitor

Greg McIntyre and Andrew R. Neureuther

J. Vac. Sci. Technol. B 21, 2800 (2003); http://dx.doi.org/10.1116/1.1625966 (6 pages) | Cited 4 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A phase shifting mask pattern consisting of an Airy pattern multiplied by a linear phase progression is introduced as a quantitative monitor for the angular distribution of illumination in optical projection printing. The proximity effect spillover from the pattern rings is in phase at the center position only for illumination from the designed off-axis illumination direction. Thus, a quantitative analysis of the intensity in a particular pupil location is available simply by measuring intensity at the center of the pattern. A theoretical analysis is presented and image simulation studies are made of an implementation based on four-phase mask making. The results show that the signal strength is high (about 1/3–1/5 of the clear field intensity per ring), the angular discrimination is good (about 0.5/ring number), and that linear phase rings are reasonably unaffected by aberrations. Mask requirements suggest this technique is most advantageous for monitoring dipoles or quadrupoles. Since the patterns print at normal exposure levels, they may also be included on product wafers to fingerprint the illumination during production. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Correction for local flare effects approximated with double Gaussian profile in ArF lithography

Morimi Osawa, Teruyoshi Yao, Hajime Aoyama, Kozo Ogino, Hiromi Hoshino, Yasuhide Machida, Satoru Asai, and Hiroshi Arimoto

J. Vac. Sci. Technol. B 21, 2806 (2003); http://dx.doi.org/10.1116/1.1629286 (4 pages) | Cited 15 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A method has been developed for correcting line width variations due to midrange flare with a scattering range of over a few tens of micrometers (which we call local flare). It is shown that the conventional single Gaussian point spread function (PSF) is not sufficient and that a double Gaussian point spread function is needed to explain the line width variation caused by local flare. The remaining errors after correction are discussed under the assumptions that the mask correction is linear with respect to local flare intensity and is independent of pattern layout considering the order of the local flare correction (LFC) and optical proximity correction (OPC). This simple sizing method can reduce the critical dimension (CD) variation regardless of whether LFC is done before or after OPC. The LFC performance was evaluated using actual 90-nm-node LSI data. A much faster correction time than that of OPC was achieved by introducing the area density map method. The CD variation due to local flare was reduced from 22 to 5 nm. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

The case for diffractive optics in maskless lithography

Dario Gil, Rajesh Menon, and Henry I. Smith

J. Vac. Sci. Technol. B 21, 2810 (2003); http://dx.doi.org/10.1116/1.1629288 (5 pages) | Cited 12 times

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
For photon-based maskless lithography we show that a system based on the incoherent addition of scanned, multiplexed, and on-axis focal spots from an array of diffractive-optical elements, such as binary-phase zone plates, has significant advantages over systems based on partially coherent projection of the image of a micromechanical mirror array through a large refractive or reflective lens. We show that zone-plate arrays with numerical apertures up to 0.9 can be manufactured with near-ideal performance, and used to achieve high-quality lithography of arbitrary patterns. Using a wavelength of 400 nm we demonstrate k1 factors as low as 0.32, without the use of any resolution-enhancement techniques; that sufficient contrast is achieved in dense patterns despite the presence of diffracted orders other than +1; and that a process-latitude greater than 10% is achieved for 150 nm lines and spaces. Advantages of our diffractive-optical approach include: the feasibility of wave-front engineering by using elements other than binary-phase zone plates; the simplicity of the processes needed to manufacture large arrays of high-numerical-aperture diffractive-optical elements; and the ease of wavelength scaling, with the promise of ultimately approaching the limits of the lithographic process. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
42.82.Cr Fabrication techniques; lithography, pattern transfer
81.16.Rf Micro- and nanoscale pattern formation
42.79.Ci Filters, zone plates, and polarizers
42.79.Bh Lenses, prisms and mirrors

Algebraic model for the printability of nonplanar phase defects

Michael Lam and Andy Neureuther

J. Vac. Sci. Technol. B 21, 2815 (2003); http://dx.doi.org/10.1116/1.1629296 (6 pages) | Cited 1 time

Online Publication Date: 5 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Algebraic thin-mask models for the printability of phase defects have been extended to the case of post and void phase defects that electromagnetically behave differently than their physical height. Any two of the three model parameters [average magnitude (M), phase (φdefect), and defect area (A)] are shown to be adequate for predicting the intensity dip for isolated defects and by implication all that is likely necessary for modeling linewidth change when defects are adjacent to features. Simple models for estimating the near-field effective brightness and near-field effective phase from defect geometries are given. The image behavior through focus of isolated defects allows the extraction of all necessary parameters and allows differentiation of phase posts and voids. SPLAT generated images using the extracted parameters show excellent agreement with the images from rigorous simulations with TEMPEST. The algebraic model can thus serve as a multidirectional link between geometries, electromagnetic scattering analyses, lithographic performance, and (by extension) inspection. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Rf Micro- and nanoscale pattern formation
81.16.Nd Micro- and nanolithography
back to top X-ray Lithography

Extreme expansion of proximity gap by double exposures using enlarged pattern masks for line and space pattern formation in x-ray lithography (evolution of exposure method to symmetric illumination)

E. Toyota, M. Washio, H. Watanabe, and H. Sumitani

J. Vac. Sci. Technol. B 21, 2821 (2003); http://dx.doi.org/10.1116/1.1629718 (5 pages)

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The extendibility of x-ray lithography is limited by the usable proximity gap. The gap is considered to be larger than 10 μm. Practically, a line and space (L/S) pattern of 70 nm linewidth and 140 nm pitch can be formed at a 10 μm gap using a 1:1 exposure mask (1× mask). If a double-pitch mask (2× mask), whose L/S pitch is twice as large as desired what to be printed on the wafer, is used while applying double exposures, the gap can be expanded greatly. A simulation result showed that using a 2× mask, a gap of more than 1000 μm can be used to form a L/S pattern of 200 nm pitch. An exposure test at a gap of 160 μm using the 2× mask proved sufficient to form the L/S pattern of 200 nm pitch. The principle of symmetric illumination explains this result well. The principle is also applicable to two-dimensional pattern formation, for which we propose a concept of mask design, i.e., the symmetric-illumination mask (SIM). Multidot images formed by the SIMs can produce mega- or giga-unit patterns of less than 25 nm linewidth by applying continuous writing. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
back to top Electron Sources and Optics

Photoelectronic analog-to-digital conversion using miniature electron optics: Basic design considerations

R. Fabian Pease, Katerina Ioakeimidi, Rafael Aldana, and Robert Leheny

J. Vac. Sci. Technol. B 21, 2826 (2003); http://dx.doi.org/10.1116/1.1621664 (4 pages) | Cited 3 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
There is a continuing need for faster and more precise analog-to-digital converters (ADCs). State of the art ADCs have reached the 10 gigasamples/second (GS/s), 6–12 bit performance. We investigate an implementation of a 100 GS/s 4–6 bit ADC. The use of a cathode ray tube for analog-to-digital conversion was first described in the 1940s. The basic idea is that a bunch of electrons passing through an electric deflection system is directed to a specific detector whence a digital code word emanates. Thus the electron bunch samples the analog deflecting voltage which is then quantized according to the position of the detector receiving the bunch. The most fundamental limit to the number of distinguishable voltage levels is the ratio of the deflecting impulse to the momentum spread due to diffraction of the electron beam. This should allow up to 12 bits at 100 GS/s. At a more practical level the bit resolution and sampling frequency are limited by the brightness of the beam, the uncertainty in the time of emission of each bunch and by the maximum power needed to generate the analog voltage used to deflect the beam. For 50 V deflecting voltage and 100 fs timing uncertainty we should be able to achieve 4–5 bits for a 50 GHz bandwidth on the analog voltage (100 GS/s). © 2003 American Vacuum Society.
Show PACS
85.60.Ha Photomultipliers; phototubes and photocathodes
84.47.+w Vacuum tubes
41.85.-p Beam optics

Effect of oxygen adsorption on the efficiency of magnesium photocathodes

Quan Yuan, Aaron W. Baum, R. Fabian W. Pease, and Piero Pianetta

J. Vac. Sci. Technol. B 21, 2830 (2003); http://dx.doi.org/10.1116/1.1624265 (4 pages) | Cited 2 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The quantum efficiency (QE) of photocathodes is key to their being used as electron sources in electron beam lithography and inspection. We have built and are using equipment for measuring quantum efficiency, weight gain, and residual gas pressure. During exposure to oxygen at 10−10–10−8 Torr, we observed an initial rise of between five- and eightfold in quantum efficiency to 0.2% followed by a decrease in QE and saturation of the oxygen uptake (weight gain). At lower oxygen pressures, the cathode exhibits a higher peak QE and larger total weight gain. The peak quantum efficiency can be kept stable to within 1% over 24 h if the ambient pressure is 2×10−10 Torr. The drop in quantum efficiency upon further exposure to oxygen at pressures >10−9 Torr suggests the growth of an oxide layer that reduces emission and the presence of a loosely bound adlayer of molecular oxygen during oxygen exposure. © 2003 American Vacuum Society.
Show PACS
85.60.Ha Photomultipliers; phototubes and photocathodes
68.43.Mn Adsorption kinetics
85.40.Hp Lithography, masks and pattern transfer

Distributed axis electron beam technology for maskless lithography and defect inspection

D. S. Pickard, T. R. Groves, W. D. Meisburger, T. Crane, and R. Fabian Pease

J. Vac. Sci. Technol. B 21, 2834 (2003); http://dx.doi.org/10.1116/1.1629291 (5 pages) | Cited 9 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The limitations to the throughput of electron beam systems employing a single axis are now well known. Accordingly there is increased activity in the exploration of multiaxis systems. The approach described here features both common focusing and common deflection, thus simplifying the problem of pattern stitching. Another feature, thought by some to be a disadvantage, is that the imaging is at unity magnification. We have designed and built a test stand that presently features one axis (or beamlet) in a large homogeneous magnetic field so that the extension to multiple axes can be seen to be straightforward. With this arrangement we have demonstrated that the resolution can be at least in the 30–50 nm range, that operation at low voltage (down to 260 V) is possible, that we can operate using multiple axes, and that secondary electrons generated by one beamlet can be confined so that it is possible to use this arrangement for high-speed inspection. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
41.85.Lc Particle beam focusing and bending magnets, wiggler magnets, and quadrupoles
back to top Photon Sources and Optics

High power 121.6 nm radiation source

Jianxun Yan and Mool C. Gupta

J. Vac. Sci. Technol. B 21, 2839 (2003); http://dx.doi.org/10.1116/1.1627801 (4 pages) | Cited 1 time

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A high power 121.6 nm radiation source based on dielectric barrier discharge (DBD) has been developed. Lamp parameters such as gas pressure, discharge tube diameter, electrode area and gap were optimized to maximize the 121.6 nm radiation power. Higher rf power was coupled to discharge by applying a flexible rf network, which matched the impedance between the source and discharge. The discharge was optimized by simulation using XOOPIC software to model the lamp. The simulation results were in agreement with our experimental measurements. The stable, high power (8 W) radiation source was achieved and it could be used as a reliable source for lithography and other applications. © 2003 American Vacuum Society.
Show PACS
42.72.Bj Visible and ultraviolet sources
84.47.+w Vacuum tubes
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer

Laser-produced-plasma light source development for extreme ultraviolet lithography

Hiroshi Komori, Tamotsu Abe, Takashi Suganuma, Yousuke Imai, Yukihiko Sugimoto, Hiroshi Someya, Hideo Hoshino, Georg Soumagne, Yuichi Takabayashi, Hakaru Mizoguchi, Akira Endo, Koichi Toyoda, and Yasuhiro Horiike

J. Vac. Sci. Technol. B 21, 2843 (2003); http://dx.doi.org/10.1116/1.1627813 (5 pages) | Cited 11 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The development status of our laser produced plasma EUV light source is reported including the xenon jet system and the 500 W laser system. Laser parameter optimization, for example, laser pulse energy, pulse width, and laser spot size, is ongoing to improve the conversion efficiency and EUV output power. A maximum conversion efficiency of 0.53% is obtained with a 50 μm diam target. The EUV output stability is analyzed based on spatial fluctuations of the Xe jet and the laser beam. In addition, a Xe ion exposure measurement has been started to investigate the collector mirror damage mechanism. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
52.50.Jm Plasma production and heating by laser beams (laser-foil, laser-cluster, etc.)
52.25.Os Emission, absorption, and scattering of electromagnetic radiation
42.72.Bj Visible and ultraviolet sources
back to top Nanodevices

Room-temperature single-electron charging effects in an ambipolar single-walled carbon nanotube grown by chemical vapor deposition

Islamshah Amlani, Ruth Zhang, John Tresek, and Raymond K. Tsui

J. Vac. Sci. Technol. B 21, 2848 (2003); http://dx.doi.org/10.1116/1.1615977 (4 pages) | Cited 4 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present single-electron charging effects in a 150 nm long ambipolar semiconducting single-walled carbon nanotube grown by chemical vapor deposition. The Coulomb blockade model explains all essential features of the data. Due to the ambipolar characteristic, the device can be tuned to be either p or n type by applying a gate voltage. In the p-type region, a single quantum dot is formed and charging behavior is observable up to 150 K. In the n-type region, transport takes place through a coupled dot system and the charging effects can be clearly seen up to room temperature. We also qualitatively discuss the model that explains the formation of two electrostatically coupled dots in the n-type region. © 2003 American Vacuum Society.
Show PACS
85.35.Kt Nanotube devices
73.23.Hk Coulomb blockade; single-electron tunneling
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.07.De Nanotubes

Fabrication and characterization of a SiGe double quantum dot structure

H. Qin, Shazia Yasin, and D. A. Williams

J. Vac. Sci. Technol. B 21, 2852 (2003); http://dx.doi.org/10.1116/1.1621659 (4 pages) | Cited 2 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Solid-state quantum dots, in which the charge and spin of excess carriers are controllable, are strong candidates for future nanoelectronics and quantum information processing. Devices based on SiGe are compatible with conventional silicon complementary metal–oxide–semiconductor processing, which allows for large-scale integration. The fabrication of SiGe double quantum dots using electron beam lithography and reactive ion etching is described. Devices are characterized electrically at cryogenic temperatures and the mixing of two microwave signals is demonstrated. © 2003 American Vacuum Society.
Show PACS
81.07.Ta Quantum dots
85.35.Be Quantum well devices (quantum dots, quantum wires, etc.)
73.63.Kv Quantum dots
81.16.Nd Micro- and nanolithography
81.65.Cf Surface cleaning, etching, patterning
84.40.-x Radiowave and microwave (including millimeter wave) technology
73.23.Hk Coulomb blockade; single-electron tunneling

Transistor structures for the study of scaling in carbon nanotubes

S. J. Wind, M. Radosavljević, J. Appenzeller, and Ph. Avouris

J. Vac. Sci. Technol. B 21, 2856 (2003); http://dx.doi.org/10.1116/1.1624260 (4 pages) | Cited 12 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the fabrication and electrical characterization of two uniquely structured carbon nanotube field-effect transistors (CNFETs). These devices have been designed to emphasize different aspects of their electrical switching behavior, so that we may learn more about their transport properties. In one structure, back-gate CNFETs were built to study the effects of vertical scaling by varying the thickness of an underlying high-quality gate dielectric. An unexpected dependence of the subthreshold slope and transconductance on the gate dielectric thickness was observed, and was attributed to Schottky barrier switching at the metal/nanotube contacts. A second structure incorporates a top gate electrode with multiple, individually addressable segments of different width. This design decouples the interior of the device from the contacts, thereby enabling the study of lateral scaling within the same physical device structure. Clear indications of bulk switching were observed in this device, with strong evidence of ballistic transport, suggesting that CNFETs do not follow conventional gate length scaling rules. © 2003 American Vacuum Society.
Show PACS
85.35.Kt Nanotube devices
85.30.Tv Field effect devices
73.63.Fg Nanotubes
73.23.Ad Ballistic transport

Single electron memory devices: Toward background charge insensitive operation

Kameshwar K. Yadavalli, Alexei O. Orlov, Gregory L. Snider, and Alexander N. Korotkov

J. Vac. Sci. Technol. B 21, 2860 (2003); http://dx.doi.org/10.1116/1.1625957 (5 pages) | Cited 4 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present an experimental study of charging mechanisms in aluminum single electron memory cells where the SiO2 surface between the floating gate and the control gate is used as a barrier dielectric and the single electron transistor is used as a readout device. We study several regimes of charging for different barriers separating the floating gate and the control gate. For thinner barriers, the floating gate acts as a single electron trap, while for thicker barriers a few tens of electrons could be stored on the floating gate to represent a bit. This allows us to realize a background charge insensitive operation of the memory cell. In devices with a barrier thickness in the range 30–100 nm we observe no charge transfer to the floating gate, but rather charging of the surface traps present in the barrier. Our results are in good agreement with theoretical calculations where specific details of device geometry are included in the model. © 2003 American Vacuum Society.
Show PACS
85.35.Gv Single electron devices
73.23.Hk Coulomb blockade; single-electron tunneling

Method for testing electronic self-assembled monolayers using a flip-chip arrangement

S. J. Spector, C. M. Wynn, M. Switkes, R. R. Kunz, S. J. Deneault, and M. Rothschild

J. Vac. Sci. Technol. B 21, 2865 (2003); http://dx.doi.org/10.1116/1.1627807 (4 pages)

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present an approach to testing large numbers of molecular-scale devices using flip-chip structures fabricated with standard micromachining techniques. The key fabrication step is the anisotropic etching of silicon to form a knife-edge structure which is 25 nm wide at its tip. To perform the testing, two chips are placed knife edge to knife edge with one chip rotated 90°. The intersecting edges from nanometer-scale probe surfaces. The test chips include micromachined stand-offs that precisely set the gap between the knife edges and enable the use of simple test apparatus to control the positioning of the probes. Preliminary test results are presented. © 2003 American Vacuum Society.
Show PACS
81.16.Dn Self-assembly
85.40.Qx Microcircuit quality, noise, performance, and failure analysis
85.65.+h Molecular electronic devices
85.30.De Semiconductor-device characterization, design, and modeling
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Influence of oxidation temperature on Si-single electron transistor characteristics

H. Namatsu, Y. Watanabe, K. Yamazaki, T. Yamaguchi, M. Nagase, Y. Ono, A. Fujiwara, and S. Horiguchi

J. Vac. Sci. Technol. B 21, 2869 (2003); http://dx.doi.org/10.1116/1.1629297 (5 pages)

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In order to make practical single-electron transistors (SET) that can operate at room temperature, it is necessary to determine the process factors that most influence their characteristics. For that purpose, the relationship between the oxidation temperature and the electrical characteristics of SETs was examined using SETs fabricated with precise dimensions by e-beam nanolithography, because a Si nanowire must be oxidized to convert it into the small Si island and tunnel barriers required for a SET. SETs fabricated using a relatively low oxidation temperature, such as 800 °C, were found to exhibit clear Coulomb blockade oscillations at room temperature; while SETs fabricated using a temperature of 900 °C did not, even though the nanowires were about the same size. At intermediate temperatures, such as 850 °C, the characteristics were between those for 800 and 900 °C oxidation. The most probable explanation for these results is as follows: The small roughness inherent to the resist is transferred to the nanowire during etching and remains after oxidation, provided that the oxidation temperature is low enough. This results in the formation of multiple islands, which can be extremely small and which enable the room-temperature operation of a Si SET due to the quantum-mechanical size effect. © 2003 American Vacuum Society.
Show PACS
85.35.Gv Single electron devices
73.23.Hk Coulomb blockade; single-electron tunneling
73.63.Nm Quantum wires
81.16.Nd Micro- and nanolithography
81.65.Mq Oxidation
85.35.Ds Quantum interference devices
81.07.Vb Quantum wires
85.40.Hp Lithography, masks and pattern transfer
81.05.Cy Elemental semiconductors
back to top Nanophotonics

Fabrication of large area subwavelength antireflection structures on Si using trilayer resist nanoimprint lithography and liftoff

Zhaoning Yu, He Gao, Wei Wu, Haixiong Ge, and Stephen Y. Chou

J. Vac. Sci. Technol. B 21, 2874 (2003); http://dx.doi.org/10.1116/1.1619958 (4 pages) | Cited 73 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this article we report on the fabrication of subwavelength antireflection structures on silicon substrates using a trilayer resist nanoimprint lithography and liftoff process. We have fabricated cone-shaped nanoscale silicon pillars with a continuous effective index gradient, which greatly enhances its antireflective performances. Our measurements show that the two-dimensional subwavelength structure effectively suppresses surface reflection over a wide spectral bandwidth and a large field of view. A reflectivity of 0.3% was measured at 632.8 nm wavelength, which is less than 1% of the flat silicon surface reflectivity. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Wc Optical coatings
81.05.Cy Elemental semiconductors
78.20.Ci Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Metallic tunable photonic crystal filter for terahertz frequencies

Timothy D. Drysdale, Gordon Mills, Susan M. Ferguson, Richard J. Blaikie, and David R. S. Cumming

J. Vac. Sci. Technol. B 21, 2878 (2003); http://dx.doi.org/10.1116/1.1622942 (5 pages) | Cited 3 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A tunable metallic photonic crystal filter has been fabricated by deep reactive ion etching of a silicon substrate followed by metallization. The filter plate’s two-layer orthogonal grid structure and integrated mounting lugs were fabricated from a single silicon wafer in two etching steps. A three-step metallization process (evaporation, sputtering, and electroplating) ensured all surfaces were coated with gold to greater than 4.6 times the skin depth at the frequencies of interest. The filter employs a mechanical tuning mechanism, the performance of which was predicted with rigorous full-vector electromagnetic simulations (finite-difference time domain). The prototype has been characterized at frequencies of 70–150 GHz using free-space measurement techniques. Its measured center frequency shifts from 144 to 137 GHz for 300 μm lateral shift of one of the plates, and it has an insertion loss of less than 1 dB. © 2003 American Vacuum Society.
Show PACS
84.40.Dc Microwave circuits
84.30.Vn Filters
42.70.Qs Photonic bandgap materials
42.82.Cr Fabrication techniques; lithography, pattern transfer
81.65.Cf Surface cleaning, etching, patterning
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
85.60.Bt Optoelectronic device characterization, design, and modeling

Patterning of circular structure arrays with interference lithography

Harun H. Solak and Christian David

J. Vac. Sci. Technol. B 21, 2883 (2003); http://dx.doi.org/10.1116/1.1622943 (5 pages) | Cited 9 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have developed an interference lithography method that enables the production of circular periodic patterns. The range of accessible patterns includes concentric circular rings, spiral- and spoke-like patterns, and dots positioned periodically on concentric circular tracks. The method is based on the use of transmission diffraction gratings to create circular beams with wave fronts that are not accessible with reflective or refractive optics. Diffraction gratings with equally spaced concentric circles are used to obtain diverging or converging conical waves with radial phase variation and spiral-like gratings are used to obtain waves with the phase varying in both radial and azimuthal directions. We have experimentally demonstrated the method with electron-beam written diffraction gratings, which we illuminated with a coherent laser beam to form the interference patterns. Many different designs are possible that bring two, three, or more beams together to form a desired interference pattern. The technique should in general be useful in applications requiring circular periodic patterns, which may include production of patterned magnetic media, spoke patterns for angular encoders, and photonic crystals with circular symmetry. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Rf Micro- and nanoscale pattern formation
81.16.Nd Micro- and nanolithography
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.25.Hz Interference

Characterization of sidewall roughness of InP/InGaAsP etched using inductively coupled plasma for low loss optical waveguide applications

J. W. Bae, W. Zhao, J. H. Jang, I. Adesida, A. Lepore, M. Kwakernaak, and J. H. Abeles

J. Vac. Sci. Technol. B 21, 2888 (2003); http://dx.doi.org/10.1116/1.1625956 (4 pages) | Cited 3 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The effects of etch depth on the sidewall roughness (SWR) of InGaAsP/InP waveguides fabricated utilizing two types of masks, NiCr/SiO2 and SiO2/NiCr/SiO2, were investigated with an atomic force microscopy. All the waveguides were etched in an inductively coupled plasma–reactive ion etching to depths ranging from 4 to 8 μm. The root-mean-square (rms) sidewall roughness values of the waveguides etched to depths of 4, 6, and 8 μm with SiO2 remasking layer were measured to be 2.97, 3.45, and 3.64 nm, respectively. Also the rms SWR values of the waveguides etched without the remasking layer were 3.2, 3.65, and 3.89 nm, respectively. The SiO2 thin remasking layer deposited on NiCr/SiO2 mask structure reduced the SWR of the waveguides. Measurements indicated that SWR increased with etch time, which is ascribed to an increase in mask erosion during etching. © 2003 American Vacuum Society.
Show PACS
42.82.Et Waveguides, couplers, and arrays
42.82.Cr Fabrication techniques; lithography, pattern transfer
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
42.79.Gn Optical waveguides and couplers
81.05.Ea III-V semiconductors
42.86.+b Optical workshop techniques
68.37.Ps Atomic force microscopy (AFM)

Evolution of line-edge roughness during fabrication of high-index-contrast microphotonic devices

Tymon Barwicz and Henry I. Smith

J. Vac. Sci. Technol. B 21, 2892 (2003); http://dx.doi.org/10.1116/1.1625965 (5 pages) | Cited 15 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have investigated the evolution of line-edge roughness during fabrication of high-refractive-index-contrast microphotonic devices. First, we present a method for estimating the spectral density of line-edge roughness. Then, the effect of common fabrication steps on line-edge roughness is reported. Spectral-density estimates are obtained from high-resolution micrographs acquired with a scanning electron microscope. Line edges are detected in the micrographs and then analyzed using various statistical methods. The impacts on roughness of liftoff, reactive-ion etching, and two non chemically-amplified electron-beam resists are quantitatively evaluated. We found that smooth sidewalls require adequate coverage of sidewalls via polymerization during reactive-ion etching, and a sharp resist profile when liftoff is used. In general, roughness can be greatly reduced by adjusting fabrication parameters. The method described in this article can be used as an efficient process optimization tool for fabrication of high-refractive-index-contrast microphotonic devices. © 2003 American Vacuum Society.
Show PACS
85.60.-q Optoelectronic devices
42.82.Cr Fabrication techniques; lithography, pattern transfer

Fabrication of three-dimensional mode converters for silicon-based integrated optics

M. Fritze, J. Knecht, C. Bozler, C. Keast, J. Fijol, S. Jacobson, P. Keating, J. LeBlanc, E. Fike, B. Kessler, M. Frish, and C. Manolatou

J. Vac. Sci. Technol. B 21, 2897 (2003); http://dx.doi.org/10.1116/1.1625967 (6 pages) | Cited 3 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
One of the key challenges facing silicon-based integrated optics is the coupling of light from standard optical fibers to submicron silicon waveguides. As a solution to this problem, we present an adiabatically tapered three-dimensional mode converter based on graytone optical lithography and silicon-on-insulator substrates. Our goal has been to preserve complementary metal–oxide–semiconductor process compatibility to the greatest extent possible. Adiabatic tapers are robust with respect to fabrication imperfections. The graytone lithography fabrication process is discussed, and results are presented from optical coupling experiments. Minimizing silicon surface roughness is critical, and methods are presented for achieving rms roughness values on the subnanometer scale. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.82.Et Waveguides, couplers, and arrays
42.81.Qb Fiber waveguides, couplers, and arrays
42.79.Gn Optical waveguides and couplers

3D structuring of multilayer suspended membranes including 2D photonic crystal structures

J. L. Leclercq, P. Rojo-Romeo, C. Seassal, J. Mouette, X. Letartre, and P. Viktorovitch

J. Vac. Sci. Technol. B 21, 2903 (2003); http://dx.doi.org/10.1116/1.1627796 (4 pages) | Cited 2 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
New types of switching devices with spatial and spectral resolution combining photonic crystal (PC) and micro-opto-electro-mechanical structures (MOEMS) are proposed. They are based on multilayer suspended high refractive index III–V-based semiconductor membranes, some of these membranes being laterally structured to form a bidimensional PC. We present a method for fabricating these devices implying an original approach that combines micro- and nanotechnologies. The PC is patterned by using electron beam lithography and reactive ion etching. The MOEMS structure is an InP-air gaps multilayer realized by a combination of classical processing of epitaxially grown layers with a selective postprocess micromachining of sacrificial epilayers. Primary demonstrator acting as a wavelength selective and “switchable” coupler including a triangular lattice of PC holes on top of a InP–air gap pair-based Bragg reflector has been realized. We present the preliminary results on the technological fabrication and optical characterizations. © 2003 American Vacuum Society.
Show PACS
42.82.Gw Other integrated-optical elements and systems
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.70.Qs Photonic bandgap materials
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
42.82.Et Waveguides, couplers, and arrays
81.16.Nd Micro- and nanolithography

Fabrication methods for a quantum cascade photonic crystal surface emitting laser

D. M. Tennant, R. Colombelli, K. Srinivasan, M. Troccoli, O. Painter, C. Gmachl, F. Capasso, A. M. Sergent, D. L. Sivco, and A. Y. Cho

J. Vac. Sci. Technol. B 21, 2907 (2003); http://dx.doi.org/10.1116/1.1627815 (5 pages)

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Conventional quantum cascade (QC) lasers are intrinsically edge-emitting devices with mode confinement achieved via a standard mesa stripe configuration. Surface emission in edge emitting QC lasers has therefore necessitated redirecting the waveguided laser emission using a second order grating. This paper describes the methods used to fabricate a 2D photonic crystal (PC) structure with or without a central defect superimposed on an electrically pumped QC laser structure with the goal of achieving direct surface emission. A successful systematic study of PC hole radius and spacing was performed using e-beam lithography. This PC method offers the promise of a number of interesting applications, including miniaturization and integration of QC lasers. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.55.Px Semiconductor lasers; laser diodes
42.55.Tv Photonic crystal lasers and coherent effects
42.60.Da Resonators, cavities, amplifiers, arrays, and rings
42.60.By Design of specific laser systems

X-ray and electron-beam lithography of three-dimensional array structures for photonics

F. Romanato, D. Cojoc, E. Di Fabrizio, M. Galli, and D. Bajoni

J. Vac. Sci. Technol. B 21, 2912 (2003); http://dx.doi.org/10.1116/1.1629295 (6 pages) | Cited 3 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The possibility to realize three-dimensional (3D) photonic crystals and the capability to internally insert a waveguide path poses a big challenge from the fabrication point of view. We present a fabrication method for a 3D lattice with designed linear defects by multitilt x-ray exposures and electron-beam lithography. This combination of different lithographies has been developed to control the design and the realization of the linear defects inside the three-dimensional structure. This method has been applied for the fabrication of Nickel Yablonovite lattices with a lattice parameter of 1.8 μm and a total thickness of 15 μm, a value that allows us to achieve a full three-dimensional optical behavior as confirmed by variable angle reflectance measurements. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
78.20.-e Optical properties of bulk materials and thin films
61.50.Lt Crystal binding; cohesive energy
42.70.Qs Photonic bandgap materials

Fabrication of high Q square-lattice photonic crystal microcavities

K. Hennessy, C. Reese, A. Badolato, C. F. Wang, A. Imamoǧlu, P. M. Petroff, and E. Hu

J. Vac. Sci. Technol. B 21, 2918 (2003); http://dx.doi.org/10.1116/1.1629298 (4 pages) | Cited 6 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This work discusses the fabrication of two-dimensional photonic crystal microcavities (PCMs) in a thin GaAs membrane. We have developed a fabrication process for square-lattice, single-hole-defect devices, a class of PCMs that is critically sensitive to fabrication accuracy, demonstrated coupling of InAs quantum dots to the cavity modes, and shown the sensitivity of the emission to the quality of the fabrication process. Reactive ion etching conditions were optimized to produce photonic crystal holes with smooth, straight sidewalls. To achieve uniform hole sizes throughout the device, we developed a method to correct the proximity effect introduced while defining the photonic crystal holes using electron-beam lithography. Resulting cavities have resonances with quality factors as high as 4000, which proves the quality of our fabrication. © 2003 American Vacuum Society.
Show PACS
42.70.Qs Photonic bandgap materials
78.20.-e Optical properties of bulk materials and thin films
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.55.Tv Photonic crystal lasers and coherent effects
78.67.Hc Quantum dots
81.07.Ta Quantum dots
back to top Nanoscale Biology

Pattern and probe-based aberration monitors for the human eye

Garth Robins and Andrew Neureuther

J. Vac. Sci. Technol. B 21, 2922 (2003); http://dx.doi.org/10.1116/1.1615976 (4 pages)

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A pattern and interferometric probe method is described for measuring aberrations in the human eye. Both subjective (human reporting) and objective (external measurement) embodiments are suggested. Simulation studies of targets are given for defocus, astigmatism, coma and trifoil. The results for the simultaneous presence of these aberrations at a combined Strehl ratio of 0.67 indicate that the aberration levels could likely each be individually quantified to an accuracy of 0.02λ rms waves such that the vision could be improved to a Strehl ratio of 0.94. © 2003 American Vacuum Society.
Show PACS
42.66.Ct Anatomy and optics of eye
07.60.Ly Interferometers
87.63.L- Visual imaging

Development of improved photosensitive polycarbonate systems for the fabrication of microfluidic devices

Celesta E. White and Clifford L. Henderson

J. Vac. Sci. Technol. B 21, 2926 (2003); http://dx.doi.org/10.1116/1.1622934 (5 pages) | Cited 1 time

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A technique was recently developed for the fabrication of microfluidic devices that involves using thermally sacrificial polymeric materials in conjunction with other conventional microelectronic processes. This method provides more versatility and choice for construction materials than other current techniques, and it enables the integration of higher levels of functionality into microfluidic systems (i.e., fully integrated multilevel fluidic systems with functional valves, pumping systems, other microelectromechanical system components, and microelectronic devices). This article describes recent results related to the development of photodefinable polycarbonates with improved properties for thermally sacrificial polymer applications. Results of the synthesis and characterization of a polycarbonate that can be directly patterned with the use of photoacid generators via acid-catalyzed thermolysis of polycarbonates are presented. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.85.Np Fluidics
82.35.Gh Polymers on surfaces; adhesion
42.70.Jk Polymers and organics

Chemical recognition based on micromachined silicon cantilever array

N. Abedinov, C. Popov, Zh. Yordanov, Tzv. Ivanov, T. Gotszalk, P. Grabiec, W. Kulisch, I. W. Rangelow, D. Filenko, and Yu. Shirshov

J. Vac. Sci. Technol. B 21, 2931 (2003); http://dx.doi.org/10.1116/1.1624261 (6 pages) | Cited 11 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the performance of a measurement system for the recognition of individual analytes and their binary mixtures which is based on a multiarray of four micromachined silicon cantivelers actuated at their resonance frequency. The cantilevers have been functionalized by organic polymers [polydimethylsiloxane (PDMS) and polyvinylpyridine (PVP)] and amorphous nitrogen-rich carbon nitride films. We found that the sensitivity and selectivity of the cantilevers coated with CNx films change according to the layer thickness. Our results show that the selected combination of sensitive layers ensures a wide range of specific, reversible and reproducible sensor responses upon exposure to methanol, 2-propanol, water and their binary mixtures. Further, it was found that the differences in recovery times of PDMS and CNx films after exposure to the two alcohols and their mixtures could be used especially for low analyte concentrations as a second characteristic in addition to the resonance frequency shift for the identification of individual components in the mixtures. © 2003 American Vacuum Society.
Show PACS
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices

Metal nanogap devices fabricated by conventional photolithography and their application to deoxyribose nucleic acid analysis

Shingi Hashioka, Masato Saito, Eiichi Tamiya, and Hideki Matsumura

J. Vac. Sci. Technol. B 21, 2937 (2003); http://dx.doi.org/10.1116/1.1625961 (4 pages) | Cited 5 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A low-cost and simple fabrication technique is proposed to prepare the metal nanogap devices (MNGDs) of sub-50 nm size. Only currently available mass-production technologies such as photolithography and anodic oxidation of patterned metal films are utilized in the technique. The gap width of MNGD can be easily and accurately controlled by the applied voltage of the anodic oxidation process. For example, the gap width formed between titanium electrodes by anodic voltage 15 V is about 10 nm, and the standard deviation (σ) of the width fluctuation is about only 2 nm (20% of the fabrication size). Thus, the accuracy of the fabrication technique is on the almost same level with the electron beam (EB) lithography. Multigap MNGD containing several different gap widths were fabricated for the use of deoxyribose nucleic acid (DNA) analysis. As an application of MNGD, pure water containing DNA was dropped on MNGD, dried in air and the current–voltage characteristics of DNA were measured. From these results, it is expected that low-cost DNA analyzer can be provided by the present technique to fabricate MNGD. © 2003 American Vacuum Society.
Show PACS
81.07.Lk Nanocontacts
85.65.+h Molecular electronic devices
87.14.G- Nucleic acids
87.85.Qr Nanotechnologies-design
87.85.Rs Nanotechnologies-applications
81.07.Nb Molecular nanostructures
81.16.Nd Micro- and nanolithography
81.16.Pr Micro- and nano-oxidation
81.16.Rf Micro- and nanoscale pattern formation
81.65.Mq Oxidation
87.80.-y Biophysical techniques (research methods)
82.80.-d Chemical analysis and related physical methods of analysis
73.63.Rt Nanoscale contacts

Fabrication of an integrated nanofluidic chip using interferometric lithography

M. J. O’Brien, P. Bisong, L. K. Ista, E. M. Rabinovich, A. L. Garcia, S. S. Sibbett, G. P. Lopez, and S. R. J. Brueck

J. Vac. Sci. Technol. B 21, 2941 (2003); http://dx.doi.org/10.1116/1.1625964 (5 pages) | Cited 23 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The fabrication of nanoscale structures with dimensions approaching the scale of biological molecules offers approaches to the study of fluid dynamics and biomolecular transport. Ultimately, a parallel lithographic approach will be necessary if devices based on these nanofluidics are to achieve widespread availability and acceptance. We report on a flexible, all-optical lithography alternative that is amenable to large-scale production. We use interferometric lithography (IL) and anisotropic etching to produce large areas of parallel, nanofluidic channels with widths of ∼100 nm and depths of up to 500 nm. We also use standard optical lithography to create interfacing microchannels, such that the range of spatial scales on one chip varies by 104 (from mm scale reservoirs to 100 nm nanochannels). We provide initial demonstrations of capillary action and electrophoretic motion of fluorescent dye solutions. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
47.85.Np Fluidics
81.16.Nd Micro- and nanolithography
81.65.Cf Surface cleaning, etching, patterning
07.60.Ly Interferometers

DNA microarrays: An imaging study

C. Kim, M. Li, A. Lowe, N. Venkataramaiah, K. Richmond, J. Kaysen, and F. Cerrina

J. Vac. Sci. Technol. B 21, 2946 (2003); http://dx.doi.org/10.1116/1.1627802 (5 pages) | Cited 3 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
DNA chips are used to study the composition of genetic material. We report the results of an experimental study of the synthesis of DNA microarrays using a maskless photodeprotection process. In these “chips,” the quality of the final product is dependent on the type and frequency of errors in the synthesis of the oligonucleotides. Contrary to photoresist, the photochemistry is linear and thus more prone to the introduction of defects. To understand and characterize the exposure process, we have developed a theoretical image formation model based on standard lithographic modeling tools. Experimentally, we have used a microarray synthesizer similar to that described in (Ref. 1), but using an argon ion laser as radiation source. To characterize the process, we have acquired aerial images using a CCD camera, a photosensitive film, and fluorescence image of a T-base monomer. We will discuss the imaging properties of the optical system, the models used to analyze the data and the relation between measured images and DNA stepwise synthesis yield. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
85.65.+h Molecular electronic devices
87.14.G- Nucleic acids
78.55.Kz Solid organic materials

Sublithographic nanofabrication technology for nanocatalysts and DNA chips

Yang-Kyu Choi, Joon Sung Lee, Ji Zhu, Gabor A. Somorjai, Luke P. Lee, and Jeffrey Bokor

J. Vac. Sci. Technol. B 21, 2951 (2003); http://dx.doi.org/10.1116/1.1627805 (5 pages) | Cited 26 times

Online Publication Date: 9 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe parallel processes for nanometer pattern generation on a wafer scale with resolution comparable to the best electron beam lithography. Sub-10 nm linewidth is defined by a sacrificial ultrathin film deposited by low pressure chemical vapor deposition (LPCVD), in a process similar to formation of gate sidewall spacers in CMOS processing. We further demonstrate a method called iterative spacer lithography (ISL), in which the process is repeated multiple times with alternating materials in order to multiply the pattern density. Silicon structures with sub-10 nm width fabricated by this process were used as a mold in nanoimprint lithography and lift-off patterning of sub-30 nm platinum nanowires for use in experiments on chemical catalysis. We also demonstrate a similar process called reversed spacer lithography (RSL) to form sub-10 nm fluid channels in poly-Si. This nanogap fluid channel device was used for label-free detection of DNA hybridization based on electrical sensing of dielectric changes in the gap. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
85.65.+h Molecular electronic devices
back to top Nano- and Microfabrication

Fabrication of high-numerical-aperture phase zone plates with a single lithography exposure and no etching

Dario Gil, Rajesh Menon, and Henry I. Smith

J. Vac. Sci. Technol. B 21, 2956 (2003); http://dx.doi.org/10.1116/1.1619957 (5 pages) | Cited 16 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a process for fabricating phase zone plates and other diffractive-optical elements that is capable of achieving high resolution, requires only a single lithography step, and no etching. For this process we use the negative resist hydrogen silsesquioxane (HSQ) (Dow Corning), which is sensitive to both electrons and x rays. HSQ’s extraordinarily high resolution (∼10 nm) and its SiO2-like properties make it an optimal choice for fabricating diffractive-optical elements that operate in the ultraviolet and deep ultraviolet. HSQ has an index of refraction very close to that of fused silica, and a negligible absorption down to 157 nm. As a result, if it is spun to the thickness corresponding to the desired phase step for the optic, patterning and development are the only required process steps. It is often desirable to place an absorbing layer on the areas surrounding the diffractive elements to prevent unwanted radiation from reaching the substrate when the optics are used for lithography and microscopy applications. We have developed a method that achieves this by means of a metal evaporation followed by a selectively controlled chemical etching (Fulton/Dolan process). We present e-beam and x-ray lithographic exposures in HSQ of phase zone plate arrays, and provide a full description of the selectively controlled chemical etching process as applied to the fabrication of diffractive optics. The focusing properties of the fabricated arrays are also presented. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.79.Ci Filters, zone plates, and polarizers

Molecular transfer lithography for pseudomaskless, high-throughput, aligned nanolithography

Charles D. Schaper

J. Vac. Sci. Technol. B 21, 2961 (2003); http://dx.doi.org/10.1116/1.1621660 (5 pages) | Cited 5 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A class of high-resolution printing methods, collectively called molecular transfer lithography (MxL), involves the replication of surface patterns as water-soluble templates. The templates are manufactured by spin-casting a polyvinyl alcohol (PVA) film-forming solution on a master pattern. The resultant water-soluble templates are then bonded to the substrate using an intervening adhesive layer that solidifies through photocuring, thermal, or two-part reactive schemes. The templates are chemically removed by dissolution with water yielding a formed pattern in the adhesion layer. Other variations of MxL include the transfer of materials to the substrate such as metals deposited on the template surface. For higher quality prints and overlay, contact alignment tools for MxL are needed. This article describes the implementation of MxL transfer schemes by adaptation of standard contact aligners normally used for photolithography. The primary modification required for integration is the replacement of the quartz photomask with the conformable water-soluble template. Results are presented to demonstrate the replication capability of MxL to sub-100 nm and the use of contact aligners to achieve deep submicron feature sizes and to enable three-dimensional printing while providing an intermediate level of overlay accuracy. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
81.16.Rf Micro- and nanoscale pattern formation

Nanoelectrode lithography and multiple patterning

A. Yokoo

J. Vac. Sci. Technol. B 21, 2966 (2003); http://dx.doi.org/10.1116/1.1621667 (4 pages) | Cited 9 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Multiple patterning of a Si substrate is performed by nanoelectrode lithography, which transfers the nanoelectrode pattern by an electrochemical reaction. By repeating the process with a line-and-space-pattern nanoelectrode, a checked pattern is successfully fabricated. The fabricated pattern is used as an etching mask to wet etch a Si substrate. The etching process has two possible results. With one, the transferred pattern additionally acts as an etching mask. With the other, only the overlapping area of the transferred pattern can act as a mask. These results derive from the flexibility of nanoelectrode lithography. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning
81.05.Cy Elemental semiconductors
68.47.Fg Semiconductor surfaces
82.45.Vp Semiconductor materials in electrochemistry
68.35.B- Structure of clean surfaces (and surface reconstruction)
82.45.Fk Electrodes
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.45.Jn Surface structure, reactivity and catalysis

Precision microcomb design and fabrication for x-ray optics assembly

Yanxia Sun, Ralf K. Heilmann, Carl G. Chen, Craig R. Forest, and Mark L. Schattenburg

J. Vac. Sci. Technol. B 21, 2970 (2003); http://dx.doi.org/10.1116/1.1621668 (5 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Silicon microcombs developed at our laboratory for the precision alignment and assembly of large-area foil optics have previously been demonstrated to achieve submicron-level assembly repeatability with submillimeter-thick flat substrates. In this article we report on a double-side deep reactive-ion etch fabrication process using silicon-on-insulator wafers which was developed to improve the microcombs’ manufacturing accuracy. © 2003 American Vacuum Society.
Show PACS
07.10.Cm Micromechanical devices and systems
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.16.-c Methods of micro- and nanofabrication and processing
81.05.Cy Elemental semiconductors
41.50.+h X-ray beams and x-ray optics
07.85.Fv X- and γ-ray sources, mirrors, gratings, and detectors
81.65.Cf Surface cleaning, etching, patterning

Fabrication of 12 nm electrically variable shallow junction metal–oxide–semiconductor field effect transistors on silicon on insulator substrates

W. Henschel, T. Wahlbrink, Y. M. Georgiev, M. Lemme, T. Mollenhauer, B. Vratzov, A. Fuchs, and H. Kurz

J. Vac. Sci. Technol. B 21, 2975 (2003); http://dx.doi.org/10.1116/1.1621670 (5 pages) | Cited 2 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electrically variable shallow junction metal–oxide–semiconductor field effect transistors on silicon on insulator have been fabricated to evaluate the suitability of fabrication processes on a nanoscale. In addition, the limits of scalability have been explored reducing gate lengths down to 12 nm. Specific attention has been paid to the overlay accuracy as required for the fabrication of these double gate structures. The superior quality of hydrogen silsesquioxane (HSQ) as electron beam resist and as mask material is demonstrated. The transistor fabricated exhibits extremely low leakage currents and relatively high on currents. The 8 orders of magnitude difference between the on and off states demonstrates conclusively large potentials for metal–oxide–semiconductor structures with critical dimensions in the 10 nm regime. © 2003 American Vacuum Society.
Show PACS
85.30.Tv Field effect devices
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer

Nanoscale topography control for the fabrication of advanced diffractive optics

J. Alexander Liddle, Farhad Salmassi, Patrick P. Naulleau, and Eric M. Gullikson

J. Vac. Sci. Technol. B 21, 2980 (2003); http://dx.doi.org/10.1116/1.1622938 (5 pages) | Cited 13 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Gray-scale electron beam lithography has been used to create high-efficiency (63%, output normalized) blazed gratings suitable for use at extreme ultraviolet (EUV) wavelengths (i.e., 13.4 nm). The total blaze height at these wavelengths is ≈7 nm. The surface topography was generated in a single processing step in hydrogen silsesquioxane (HSQ). This material converts to SiO2 upon exposure and forms a robust substrate for subsequent operations, unlike conventional organic resists. The HSQ is overcoated with a Mo/Si multilayer to provide reflectivity at EUV wavelengths. The grating efficiency is determined by the fidelity of the profile to the ideal and by the surface roughness of the HSQ. A region of the resist response curve was identified that enabled sufficient topography to be generated while maintaining the surface roughness of the resist below 2.5 nm root mean square. Large area (0.5×2.0 mm2) gratings were fabricated, and the resulting dose profile was adjusted during the course of the exposure to compensate for observed delay-time/reciprocity effects in HSQ. © 2003 American Vacuum Society.
Show PACS
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.40.Eq Holographic optical elements; holographic gratings
42.79.-e Optical elements, devices, and systems
68.35.B- Structure of clean surfaces (and surface reconstruction)

Transient temperature measurements of resist heating using nanothermocouples

Dachen Chu, Wai-Kin Wong, Kenneth E. Goodson, and R. Fabian W. Pease

J. Vac. Sci. Technol. B 21, 2985 (2003); http://dx.doi.org/10.1116/1.1624255 (5 pages) | Cited 6 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Resist heating is one of the major factors that causes feature size variation and pattern displacement in photomask fabrication. A number of models have been published to predict the rise in temperature during resist heating, but no transient temperature experimental results are available to verify those models. We have fabricated thin film gold/nickel thermocouples with junction areas as small as 100 nm2 on silicon and 500 nm2 on quartz. Microsecond scale transient resist heating measurements were obtained using these thermocouples. Irradiation by a 15 keV, 150 nA electron beam of 1.7 μm radius for 100 μs yielded temperature rises at the resist bottom surface of approximately 62 K on quartz substrates and of 18 K on silicon substrates. Simulation results using a multilayer Green’s function model are in reasonable agreement with these experimental data for smaller temperature rises but tend to overestimate by about 10% for larger rises in temperature. In our experiments, a 100 ms exposure is equivalent to a dose of 150 μC/cm2. Under the same electron beam conditions electron dosages of 5 and 15 μC/cm2 result in temperature rises of 25 and 40 K, respectively, on quartz substrates. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
07.20.Dt Thermometers

Carbon nanopillar laterally grown with electron beam-induced chemical vapor deposition

J. Fujita, M. Ishida, T. Ichihashi, Y. Ochiai, T. Kaito, and S. Matsui

J. Vac. Sci. Technol. B 21, 2990 (2003); http://dx.doi.org/10.1116/1.1624259 (4 pages) | Cited 33 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We found that the lateral growth of a carbon nanopillar with electron beam-induced chemical vapor deposition (EB-CVD) was mainly dominated by forward scattering of the electron beam. The minimum diameter of the carbon nanopillar was reduced to 5 nm. In contrast, vertical growth with EB-CVD produced thicker pillars ∼50 nm in diameter, with a shape that reflected forward scattering of the primary electrons. Graphitization of the amorphous carbon nanopillars was also demonstrated by annealing, in which nanoiron particle traces were graphitized. © 2003 American Vacuum Society.
Show PACS
81.07.Bc Nanocrystalline materials
81.05.U- Carbon/carbon-based materials
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Jj Ion and electron beam-assisted deposition; ion plating
61.72.Cc Kinetics of defect formation and annealing
61.46.-w Structure of nanoscale materials

Nonlithographic approach to nanostructure fabrication using a scanned electrospinning source

David Czaplewski, Jun Kameoka, and H. G. Craighead

J. Vac. Sci. Technol. B 21, 2994 (2003); http://dx.doi.org/10.1116/1.1627800 (4 pages) | Cited 7 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We have used deposited polymeric nanofibers as nonlithographic templates for the fabrication of semiconductor nanostructures. We deposited oriented poly(methyl methacrylate) (PMMA) fibers, with diameters ranging from 85 to 350 nm, on the surface of various substrates using a microfabricated electrospinning source. By utilizing the small apex of a microfabricated source, a stable Taylor cone was formed as an electrostatically driven source of polymer solution directed toward the substrate. By attaching the target substrate to a rotating counter electrode, isolated and oriented PMMA fibers were deposited. We used these fibers as etch masks to pattern nanostructures in the surface of a silicon wafer. This method provides a simple, nonlithographic approach to forming nanostructures on a wide variety of substrates, such as silicon, aluminum, silicon dioxide, silicon nitride, and glass. The fiber deposition can be oriented with respect to surface features, allowing for realization of nanodevice architectures. © 2003 American Vacuum Society.
Show PACS
81.16.Rf Micro- and nanoscale pattern formation
81.65.Cf Surface cleaning, etching, patterning

Fabrication of SiC microelectromechanical systems using one-step dry etching

Liudi Jiang, R. Cheung, M. Hassan, A. J. Harris, J. S. Burdess, C. A. Zorman, and M. Mehregany

J. Vac. Sci. Technol. B 21, 2998 (2003); http://dx.doi.org/10.1116/1.1627804 (4 pages) | Cited 13 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A simple one-step inductively coupled plasma etching technique has been developed for the fabrication of SiC resonant beam structures. Straight cantilever and bridge devices have been made successfully. The structures have been actuated and resonant frequencies ranging from ∼120 kHz to ∼5 MHz have been measured. Comparison of the theoretically simulated and experimentally measured resonant frequencies shows the presence of significant tensile stress in bridge structures while the cantilever beams are free of stress. The degree of the tension in the bridge structures has been found to be independent of the bridge length. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.65.Cf Surface cleaning, etching, patterning

Nanoscopic magnetic field sensor based on extraordinary magnetoresistance

S. A. Solin, D. R. Hines, A. C. H. Rowe, J. S. Tsai, and Yu A. Pashkin

J. Vac. Sci. Technol. B 21, 3002 (2003); http://dx.doi.org/10.1116/1.1627811 (5 pages) | Cited 4 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The design, fabrication, and performance of a nanoscopic magnetic field sensor based on the newly discovered phenomenon of extraordinary magnetoresistance (EMR) are reported. It is shown that a sensor with an active volume of 35 nm length×30 nm width×20 nm height yields room temperature EMR values as high as 35% at an applied field of 0.05 T. The mesoscopic physics implications of these new results are discussed. © 2003 American Vacuum Society.
Show PACS
07.55.Ge Magnetometers for magnetic field measurements
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
73.50.Jt Galvanomagnetic and other magnetotransport effects (including thermomagnetic effects)
75.47.-m Magnetotransport phenomena; materials for magnetotransport

Fabrication of quasi-three-dimensional micro/nanomechanical components using electron beam cross-linked poly (methyl methacrylate) resist

W. H. Teh and C. G. Smith

J. Vac. Sci. Technol. B 21, 3007 (2003); http://dx.doi.org/10.1116/1.1629290 (5 pages) | Cited 5 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present a useful, flexible, and simple surface nanomachining technique which employs electron beam cross-linked poly (methyl methacrylate) (PMMA) as a high-resolution negative resist for the sacrificial layer. This technique simplifies the fabrication of quasi-three-dimensional micro/nanomechanical components without the need to pile up two-dimensional layers. The high compliance of cross-linked PMMA allows the stress relaxation of the mechanical structures to begin after the deposition of each mechanical layer. This happens prior to the stiction-free dry release step. The fact that it can be used both as an insulating layer and sacrificial layer allows the high-resolution patterning of micro/nanomechanical structures alongside unique multilayer devices. We demonstrate this technique by the characterization of PMMA as a function of electron irradiation levels and by referring to fabricated micro/nanoelectromechanical structures and devices. © 2003 American Vacuum Society.
Show PACS
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
81.16.Nd Micro- and nanolithography
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
07.10.Cm Micromechanical devices and systems

Fabrication of ultrashort T gates using a PMMA/LOR/UVIII resist stack

Y. Chen, D. S. Macintyre, X. Cao, E. Boyd, D. Moran, H. McLelland, M. Holland, C. R. Stanley, I. Thayne, and S. Thoms

J. Vac. Sci. Technol. B 21, 3012 (2003); http://dx.doi.org/10.1116/1.1629292 (5 pages) | Cited 3 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In this article, we report a procedure for the fabrication of ultrashort T gates using high resolution electron beam lithography and a PMMA/LOR/UVIII resist stack. The intermediate lift-off resist (LOR) layer improves the quality of gate lithography, and consequently, device yields. It is unaffected by wet chemical gate recessing procedures and we report the application of the procedure to the fabrication of pseudomorphic and metamorphic high electron mobility transistors (pHEMTs) with 50 nm T gates. Fabricated pHEMTs had a gm of 600 mS/mm and ft of 200 GHz. Metamorphic HEMTs had a gm of 1500 mS/mm and ft of 350 GHz. We believe these are the fastest transistors of their kind in the world. © 2003 American Vacuum Society.
Show PACS
85.30.Tv Field effect devices
85.40.Hp Lithography, masks and pattern transfer
73.61.Ph Polymers; organic compounds

Fabrication of sub-50 nm critical feature for magnetic recording device using electron-beam lithography

XiaoMin Yang, Andrew Eckert, Keith Mountfield, Harold Gentile, Carl Seiler, Stanko Brankovic, and Earl Johns

J. Vac. Sci. Technol. B 21, 3017 (2003); http://dx.doi.org/10.1116/1.1630331 (4 pages) | Cited 9 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report an electron-beam lithography method for printing and plating sub-50 nm isolated trenches with a high aspect ratio (AR) for the nanofabrication of magnetic thin-film heads. To eliminate the issues of resist footing and resist residue in the narrow trench process, we coated a thin dissolution layer of polymethylglutarimide (PMGI) as an undercoat layer between a seed layer and a resist layer. The undercoat PMGI layer was easily and more quickly dissolved than the top resist layer, so it completely cleared the trench during the develop process. In addition, a vertical sidewall at the bottom of the narrow trench was achieved by controlling the processing conditions, e.g., bake temperature and thickness of the dissolution layer. All of these allowed us to facilitate plating the narrow trench with a high magnetic moment material. In this work, narrow trenches were electroplated with both 1.0 T NiFe and 1.8 T CoNiFe alloys. We demonstrated the capability of fabricating narrow electrodeposited magnetic write top pole structures with a critical dimension (CD) of 30 nm in a 0.24 μm resist (AR=8:1) and a CD of 22 nm in a 0.11 μm resist (AR=5:1). © 2003 American Vacuum Society.
Show PACS
85.70.Kh Magnetic thin film devices: magnetic heads (magnetoresistive, inductive, etc.); domain-motion devices, etc.
81.16.Nd Micro- and nanolithography
81.15.Pq Electrodeposition, electroplating
82.45.Qr Electrodeposition and electrodissolution
75.50.Ss Magnetic recording materials
81.05.Bx Metals, semimetals, and alloys
back to top Masks

Damage-free extreme ultraviolet mask with TaBN absorber

Tsutomu Shoki, Takeru Kinoshita, Noriyuki Sakaya, Morio Hosoya, Ryo Ohkubo, Yoh-ich Usui, Hideo Kobayashi, and Osamu Nagarekawa

J. Vac. Sci. Technol. B 21, 3021 (2003); http://dx.doi.org/10.1116/1.1610004 (6 pages) | Cited 2 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article presents the results of evaluation of process-induced damage and improved reflectivity of an extreme ultraviolet (EUV) mask fabricated using a blank consisting of a multilayer, a Si capping layer, a CrN buffer layer, and a TaBN absorber. Long-term storage causes a centroid wavelength shift and stress change in the multilayer. The multilayer blank annealed at 90 °C was quite stable in centroid wavelength and film stress against resist baking at 135 °C and air storage. After the CrN buffer layer was etched with a mixture of Cl2 and O2 gases, the mask featured reflectivity loss of 1.5% due to the additional oxide layer generated on the Si capping layer. The reflectivity loss was able to be completely restored to its original value by treatment with a diluted HF solution. An EUV mask with a high reflectivity of 65% and excellent reflectivity uniformity of 0.7% 3σ was demonstrated using a blank consisting of a 40-period multilayer and a Si capping layer through a newly developed damage-free process that includes HF treatment. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
61.72.Cc Kinetics of defect formation and annealing
81.65.Cf Surface cleaning, etching, patterning

Predicting critical dimension uniformity in advanced electron-beam projection lithography masks

Eric P. Cotte, Andrew R. Mikkelson, Oscar Matesanz, Roxann L. Engelstad, Edward G. Lovell, and Phillip L. Reu

J. Vac. Sci. Technol. B 21, 3027 (2003); http://dx.doi.org/10.1116/1.1614251 (5 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Meeting the stringent budgets for both overlay errors and critical dimensions (CDs) for the insertion of next-generation lithographies requires that the sources of mask-related distortions be identified and minimized. Such sources include the mask fabrication process, electron-beam patterning, and exposure conditions. This article describes numerical simulations to characterize CD nonuniformities for the stencil format of the electron-beam projection lithography PREVAIL mask. Finite element (FE) submodeling and equivalent modeling techniques were used to investigate CD uniformity for a worst-case scenario. Whereas a global model is sufficient to predict mask overlay errors, submodeling and statistical analyses are necessary to characterize mask CD errors. The FE simulations illustrate that CD nonuniformities (from mask fabrication) can be limited to 1.0 nm, if the maximum membrane prestress is monitored and controlled. Such results comply with the CD error budgets set for the sub-65-nm lithography nodes. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Fabrication of a continuous diamondlike carbon membrane mask for electron projection lithography

Isao Amemiya, Hiroshi Yamashita, Sakae Nakatsuka, Mitsuharu Tsukahara, and Osamu Nagarekawa

J. Vac. Sci. Technol. B 21, 3032 (2003); http://dx.doi.org/10.1116/1.1618236 (5 pages) | Cited 5 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Fabrication of 8 in. high-performance continuous diamondlike carbon (DLC) membrane masks for electron projection lithography is described. The mask substrate materials and structures were optimized by evaluating the lithographic performance of the mask. The optimum mask consists of a sandwich structure, consisting of a thicker DLC scatter/a CrNx etching stopper/and a thin DLC support membrane on a bulk silicon wafer. The internal stress of each film component can be controlled by adjusting the film deposition conditions. A DLC film can be easily etched by oxygen gas, and the CrNx etching stopper has a high etching durability. Highly accurate pattern properties can be obtained while also meeting performance requirements. The critical dimension accuracy of a DLC scatterer was less than ±5% with a 280-nm-feature size in a 135×43 mm field. The electron aperture transmittance of a 44-nm-thick DLC membrane, measured by energy and angular distribution analysis for membrane, was 13 times as high as the 150-nm-thick SiNx membrane. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Predicting the thermomechanical distortion of extreme ultraviolet lithography reticles for preproduction and production exposure tools

A. Abdo, B. La Fontaine, and R. Engelstad

J. Vac. Sci. Technol. B 21, 3037 (2003); http://dx.doi.org/10.1116/1.1619955 (4 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The thermomechanical distortion of extreme ultraviolet lithography (EUVL) reticles during exposure may lead to significant image placement (IP) errors. As throughput requirements for high-volume manufacturing (HVM) increase, the necessary illumination power levels rise, resulting in further distortion of the reticle. The thermal response of the EUVL reticle is predicted using finite element models for a typical HVM exposure tool. The effect of increasing the EUV source power on reticle heating is investigated by comparing the thermal distortion expected in exposure tools using different throughput values corresponding to the α tool, β tool, and the HVM exposure tool (γ tool). The effect of imperfect contact between the EUVL reticle and the chuck surface on the IP errors due to thermal distortion is studied for different effective contact area ratios. Also, an alternative design concept is proposed, aimed at providing a solution to the microparticle trapping problem (between the reticle and the chuck). © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Mask process proximity correction for next-generation mask fabrication

Soon Ho Kim, Sung-Woon Choi, Jung-Min Sohn, and Jong Rak Park

J. Vac. Sci. Technol. B 21, 3041 (2003); http://dx.doi.org/10.1116/1.1621663 (5 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
As the requirements for minimum resolution on masks continue to tighten, performing proximity correction for mask making will be even more necessary. Mask process correction MPC with a two-Gauss kernel can be used in order to analyze and correct mask process proximity effects. From measured critical dimension (CD) linearity and two-Gauss model, the process kernel parameters α (range of spot size), β (range of dry-etching and development process) and η′ (contribution ratio of β over α) were extracted, and MPC was performed on the layout of linearity patterns by applying biases to the edge elements of the design. The CD linearity was dramatically improved even for small pattern sizes; the CD values of isolated spaces, lines and spaces, contacts, and isolated lines varied only by 10 nm for 1 μm down to 100 nm feature size pattern. The MPC concept demonstrated in this article has the potential to push the mask-making resolution limit to an even smaller size than 100 nm patterns without any deterioration in CD linearity. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Dynamic model for predicting in-plane displacement of extreme ultraviolet mask due to chucking

Akira Chiba, Minoru Sugawara, and Iwao Nishiyama

J. Vac. Sci. Technol. B 21, 3046 (2003); http://dx.doi.org/10.1116/1.1622940 (6 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A simulation model was devised to predict the in-plane displacement (IPD) of an extreme ultraviolet mask during a chucking operation with friction. The model is based on the theory of two-dimensional plane stress, and employs time evolution to predict the dynamic response of IPD. The IPD for a stepwise chucking force was found to reach a stationary state in 100 μs, after the vibrations attenuated. With regard to glass ceramic materials for the substrate, the effect of the coefficient of friction on IPD during a chucking operation was investigated. The IPD was found to decrease as the pattern density decreased. In order to reduce the IPD due to chucking, it is necessary to reduce the stress of the multilayer and absorber films, and to employ a substrate material with a high Young’s modulus. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Effects of chrome pattern characteristics on image placement due to thermomechanical distortion of optical reticles during exposure

A. Abdo, L. Capodieci, I. Lalovic, and R. Engelstad

J. Vac. Sci. Technol. B 21, 3052 (2003); http://dx.doi.org/10.1116/1.1622941 (5 pages) | Cited 2 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
As optical lithography is extended to the sub-90 nm nodes, more stringent requirements are placed on the mask critical dimension and registration budget. Errors in image placement (IP) due to exposure-induced thermal loading of the optical reticle can be a significant contribution to the overlay error budget. Thermal loading on the mask is primarily caused by the chrome pattern that absorbs a large fraction of exposure light. The effects of the chrome pattern density, local pattern distribution, and chrome reflectivity were studied using three-dimensional finite-element models for both 193 and 157 nm technologies. It was found that the chrome pattern density has a stronger influence on the thermomechanical response than the pattern distribution. Also, it was found that as the chrome reflectivity increases, the reticle maximum temperature rise decreases, thus it follows a linear relationship. In addition, various reticle/chuck mounting designs were investigated to identify what type of configuration is necessary to reduce IP errors. The effects of different exposure tool parameters and resist sensitivities on IP errors were also evaluated. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Fabry–Pérot structures for attenuated phase-shifting mask application in ArF and F2 lithography

H. L. Chen, H. S. Wu, C. C. Lee, F. H. Ko, Wonder Fan, and C. I. Hsieh

J. Vac. Sci. Technol. B 21, 3057 (2003); http://dx.doi.org/10.1116/1.1624251 (5 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate a structure for an attenuated phase-shifting mask (APSM) which is based on a three-layer Fabry–Pérot structure for ArF (193 nm) and F2 (157 nm) excimer laser based lithographies. The APSM structure is composed of a metal/dielectric/metal stack. The optical characteristics of the Fabry–Pérot structure meet the following requirements: 180° phase shift, transmittance in the range of 4%–15%, reflectance of less than 10% at the exposure wavelength, and high inspection contrast at the inspection wavelength. Common dielectric and metal materials, such as chromium, tungsten, amorphous silicon, silicon dioxide, aluminum oxide, and aluminum nitride films, can be used to construct the Fabry–Pérot structure. The top metal layer can also prevent charge accumulation during electron-beam writing. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
42.79.-e Optical elements, devices, and systems
78.66.Bz Metals and metallic alloys
78.66.Nk Insulators
78.40.Ha Other nonmetallic inorganics
78.40.Kc Metals, semimetals, and alloys

Ultrathin TiO2 amorphous films for high transmittance APSM blanks at 157 and 193 nm wavelength simultaneously

F. D. Lai, C. M. Chang, L. A. Wang, and T. S. Yih

J. Vac. Sci. Technol. B 21, 3062 (2003); http://dx.doi.org/10.1116/1.1624252 (5 pages) | Cited 2 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Ultrathin TiO2 amorphous films are deposited on ultraviolet grade fused silica substrates and CaF2 by using rf reactive unbalanced magnetron sputtering from a Ti metal target in atmosphere of Ar and O2. For an O2/Ar flow rate ratio of more than 1.5, the deposited TiO2 thin films are stoichiometric. TiO2 thin films that meet the optical requirements of a high transmittance attenuated phase-shifting mask (HTAPSM) at 157 and 193 nm wavelengths can also be properly inspected since the transmittance at 257 nm wavelength is less than 28%. The simulated thickness range of such a TiO2 thin film is found to be between 16 and 20 nm. A TiO2 amorphous thin film with thickness of 23.5 nm, transmittance of 24.9% and reflectance of 15.0% at wavelength of 193 nm, transmittance of 16.3% at 157 nm wavelength and transmittance of 23.0% at 257 nm wavelength is shown to be able to serve as an absorber layer for HTAPSM blanks at 157 and 193 nm wavelength. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.15.Cd Deposition by sputtering
42.79.Wc Optical coatings

Testing new chemistries for mask repair with focused ion beam gas assisted etching

Andrei Stanishevsky, Klaus Edinger, Jon Orloff, John Melngailis, Diane Stewart, Alvina Williams, and Richard Clark

J. Vac. Sci. Technol. B 21, 3067 (2003); http://dx.doi.org/10.1116/1.1624253 (5 pages) | Cited 2 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
In modern photolithography mask repair, shorter exposure wavelengths, smaller dimensions, and tighter process latitudes pose new challenges. We have systematically investigated focused ion beam (FIB) gas assisted etching (GAE) of chrome and mask transmission at 193 nm ultraviolet (UV) irradiation for various FIB parameters. The gases, used either alone or in binary combinations, include XeF2, Cl2, NH3, CO, CO2, Br2, H2O, and O2. While the bromine GAE appears to be the most effective among single gases in etching chrome, the quartz transmission after chrome removal remains ∼50% compared with unexposed material, and residue is present. The gas mixtures NH3/Br2 and CO2/Br2 were found to reduce the amount of residue and to enhance the chromium mask etching rate compared to Br2-only etching. This enhancement occurs in a narrow range of gas partial pressures, and the FIB process may need to be optimized further. The best transmission at 193 nm UV irradiation of the FIB GAE repaired regions achieved to date with no postprocessing is ∼95% of the transmission of a blank mask. We also applied laser power to heat the area where the ion beam is incident. No increase in Cr removal rate was seen for the Br based chemistries. Some increase in removal rate was seen for Cl2+O2 and XeF2 but the overall rate with both gas and laser power was barely higher than sputtering alone. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning
68.35.Ct Interface structure and roughness

Benchmarking stencil reticles for electron projection lithography

O. R. Wood, W. J. Trybula, M. J. Lercel, C. W. Thiel, M. J. Lawliss, K. Edinger, A. Stanishevsky, S. Shimizu, and S. Kawata

J. Vac. Sci. Technol. B 21, 3072 (2003); http://dx.doi.org/10.1116/1.1624263 (6 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Electron projection lithography (EPL) is one of the leading candidates for next-generation lithography at the 65 nm lithography node, particularly for contact levels. This article describes the results of an experimental effort to benchmark the current state of EPL stencil mask making. In this article, we report on the current status of the data handling software needed to pattern an EPL stencil reticle, EPL stencil reticle repair techniques, and EPL stencil mask stability following prolonged electron-beam irradiation. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Phase masks working in 157 nm wavelength fabricated by immersion interference photolithography

W. C. Cheng and L. A. Wang

J. Vac. Sci. Technol. B 21, 3078 (2003); http://dx.doi.org/10.1116/1.1625958 (4 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We demonstrate that phase masks can be made from modified fused silica with a period of 180 nm and ∼8 mm long by using immersion interference photolithography. The fabrication process of the phase mask is optimized to generate the largest intensity ratio of diffracted ±1 to 0 order. The phase mask is demonstrated to produce a photoresist pattern with halved period (90 nm) when illuminated with a laser of 157 nm wavelength. The phase masks are also capable of generating two-dimensional patterns of holes and dots and serving as molds for imprint applications. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
81.65.Cf Surface cleaning, etching, patterning
81.10.Fq Growth from melts; zone melting and refining

Adaptive membrane masks

X. Zhuang, D. Conkerton, A. Lal, L. Jiang, M. Feldman, T. O’Reilly, and H. Smith

J. Vac. Sci. Technol. B 21, 3082 (2003); http://dx.doi.org/10.1116/1.1625959 (4 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
As overlay requirements for integrated circuits have tightened, the control of mask distortions has become critically important. Rather than make the mask as rigid as possible, a feedback approach has been suggested in which overlay is measured and corrective displacements are thermally generated in a membrane mask. The principle corresponds to that used in adaptive optics, where an active feedback system is used to maintain perfect wave-fronts by distorting the optical surfaces. An important advantage of adaptive masks is that the feedback may be used either to obtain absolute accuracy, or to incorporate desired displacements, for example, to compensate for distortions in previous levels patterned on the wafer. Previous work focused on modeling the temperature distributions required for arbitrary mask displacement distributions. This modeling has now been verified in two very dissimilar experimental arrangements. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
42.40.Kw Holographic interferometry; other holographic techniques
42.87.Bg Phase shifting interferometry

Extreme ultraviolet mask fabrication with high inspection contrast TaSiNx absorber stack

J. R. Wasson, E. J. Weisbrod, B. Lu, P. J. S. Mangat, W. J. Dauksher, D. J. Resnick, J. Sohn, R. Engelstad, and D. Pettibone

J. Vac. Sci. Technol. B 21, 3086 (2003); http://dx.doi.org/10.1116/1.1625962 (5 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Extreme ultraviolet lithography (EUVL) is a leading candidate for next generation lithography with the potential for extendibility beyond the 45 nm node. The three-layer absorber stack for EUVL reticles consists of an absorber, repair buffer and etch stop layers, while a two-layer absorber stack eliminates the etch stop layer. Improving inspection contrast is critically important to finding defects. In previous work, using TaSiN as the EUV absorber, the inspection contrast was less than 10%, which did not allow for effective defect detection to occur. However, other TaSiN properties such as thin film stress control and critical dimension etch bias were clearly superior to the Cr absorber. An improved process using a Ta-based absorber stack that maintains the beneficial characteristics of the film, on SEMI Standard P1-92 6025 format substrates, is discussed. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning
78.67.Pt Multilayers; superlattices; photonic structures; metamaterials

Extreme ultraviolet lithography mask flatness and electrostatic chucking analysis

A. Mikkelson, R. Engelstad, E. Lovell, K. Blaedel, and A. Claudet

J. Vac. Sci. Technol. B 21, 3091 (2003); http://dx.doi.org/10.1116/1.1627810 (6 pages) | Cited 4 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The Semiconductor Industry Association Roadmap for Extreme Ultraviolet Lithography (EUVL) calls for significant improvements in the quality and flatness of the substrate and patterned mask. Due to the difficulty of meeting the mask flatness specifications, an alternative strategy has been proposed to ensure that suitable substrates will be available for EUVL. A new SEMI standard for EUVL electrostatic chucks is currently being developed. If such a standard were established, then the flatness requirements for the substrate might be relaxed to permit certain types of bow that can later be flattened by the chuck. The purpose of this study is to identify which shapes can indeed be flattened by an electrostatic chuck. To support the proposed strategy, it is essential that the clamping ability of the electrostatic chuck be characterized and well-understood. The ability of the chuck to flatten the mask will depend primarily on the mechanical stiffness of the chuck and the clamping pressure. Legendre polynomials have been identified as an effective and efficient means of representing EUVL mask surface shapes. Finite element (FE) models have been developed to utilize the Legendre polynomials as input data to define the surfaces of the reticle. The FE models were then used to determine the clamping response of the various mask shapes. In particular, the maximum reticle-to-chuck gap within the flatness quality area and over the entire reticle has been tracked as a function of clamping pressure and chuck thickness for the low-order Legendre modes. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
02.70.Dh Finite-element and Galerkin methods
back to top Metrology

Nanometer-level repeatable metrology using the Nanoruler

Paul T. Konkola, Carl G. Chen, Ralf K. Heilmann, Chulmin Joo, Juan C. Montoya, Chih-Hao Chang, and Mark L. Schattenburg

J. Vac. Sci. Technol. B 21, 3097 (2003); http://dx.doi.org/10.1116/1.1610003 (5 pages) | Cited 18 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We report on the measurement of the fringe-to-substrate phase error in our Nanoruler system. This system utilizes scanning beam interference lithography to pattern and measure large-area, nanometer-accuracy gratings that are appropriate for semiconductor and integrated opto-electronic metrology. We present the Nanonruler’s metrology system that is based on digital frequency synthesizers, acousto-optics, and heterodyne phase sensing. It is used to assess the fringe-to-substrate placement stability and the accuracy of the feedback signals. The metrology system can perform measurements in real time, on the fly, and at arbitrary locations on the substrate. Experimental measurements are presented that demonstrate the nanometer-level repeatability of the system. Dominant error sources are highlighted. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
42.79.Dj Gratings
07.60.Ly Interferometers
06.20.Dk Measurement and error theory

Micromachined atomic force microscopy sensor with integrated piezoresistive sensor and thermal bimorph actuator for high-speed tapping-mode atomic force microscopy phase-imaging in higher eigenmodes

R. Pedrak, Tzv. Ivanov, K. Ivanova, T. Gotszalk, N. Abedinov, I. W. Rangelow, K. Edinger, E. Tomerov, T. Schenkel, and P. Hudek

J. Vac. Sci. Technol. B 21, 3102 (2003); http://dx.doi.org/10.1116/1.1614252 (6 pages) | Cited 19 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
This article describes microprobes for noncontact scanning force microscopy that make use of a direct-oscillating thermally driven bimorph actuator with integrated piezoresistive readout sensor. The sensitivity has been increased using direct current for biasing and alternating current for exciting the thermally driven cantilever in a higher flexural mode. The cantilever operates in the phase-shift atomic force microscopy (AFM) detection technique. The main advantage of phase imaging is the higher z resolution at high scan rates and much lower forces than in height imaging with contact AFM. Critical dimensions measurements illustrating the imaging capability and resolution of our new scanning proximal probe are demonstrated. © 2003 American Vacuum Society.
Show PACS
07.79.Lh Atomic force microscopes

Demonstration of 20 nm half-pitch spatial resolution with soft x-ray microscopy

W. Chao, E. H. Anderson, G. Denbeaux, B. Harteneck, A. L. Pearson, D. Olynick, F. Salmassi, C. Song, and D. Attwood

J. Vac. Sci. Technol. B 21, 3108 (2003); http://dx.doi.org/10.1116/1.1619956 (4 pages) | Cited 7 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The full field, transmission soft x-ray microscope XM-1 is a valuable imaging instrument for many scientific and technological areas involving nanometer features. Operating from 300 to 1800 eV, it combines high spatial resolution, elemental discrimination, magnetic sensitivity, and a capability of imaging in various experimental conditions, such as with applied magnetic fields and electric currents. In this article, we report experiments that enable accurate spatial resolution measurement, using a new type of test pattern, made from thinned multilayer coatings. The resolution of the microscope was measured to be 20 nm, using this method. © 2003 American Vacuum Society.
Show PACS
07.85.Tt X-ray microscopes
68.37.Yz X-ray microscopy
68.65.Ac Multilayers

Interferometric-spatial-phase imaging for six-axis mask control

Euclid E. Moon, Lynn Chen, Patrick N. Everett, Mark K. Mondol, and Henry I. Smith

J. Vac. Sci. Technol. B 21, 3112 (2003); http://dx.doi.org/10.1116/1.1619960 (4 pages) | Cited 16 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We describe a unified approach to measuring alignment and gap with nanometer detectivity between two planar objects (e.g., a mask and a substrate) in close proximity. The method encodes lateral position in the phase of interference fringes, formed by diffraction from grating and checkerboard alignment marks, designed to enable a wide acquisition range. For gapping, the method incorporates, in the same mark, coarse-gap detection (30–300 μm) and absolute-gap detection at sub-30 μm using a chromatic Fabry–Pérot scheme. Fine detection of sub-30 μm gaps is inferred from the frequency and phase of fringes, calibrated using the chromatic Fabry–Pérot. Illumination with a variable-bandwidth source enables either “achromatic” aligning or “chromatic” gapping. Sub-nanometer detection and feedback control of mask position is demonstrated in X, Y, and θ. Overlay of exposed patterns is demonstrated to be <3 nm. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Advances in nanolithography using molecular rulers

M. E. Anderson, L. P. Tan, H. Tanaka, M. Mihok, H. Lee, M. W. Horn, and P. S. Weiss

J. Vac. Sci. Technol. B 21, 3116 (2003); http://dx.doi.org/10.1116/1.1621662 (4 pages) | Cited 16 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The combination of conventional lithographic techniques with chemical self-assembly allows for the creation of nanostructures whose spacing and edge resolution reach nanometer-scale precision. The controlled placement and thickness of self-assembled multilayers composed of alternating layers of α,ω-mercaptoalkanoic acids and coordinated metal ions form precise “molecular ruler” resists that enable the production of tailored and lithographically defined metal patterns. Initial structures created by conventional techniques are referred to as parents and subsequent structures generated by the molecular ruler process are identified as daughters. We report the further creation of subsequent generation structures (granddaughters) that have sub-100 nm dimensions. The granddaughter structures are created by forming molecular rulers on parent and daughter structures, and can be isolated by removing sacrificial parent and/or daughter structures. This process has also been utilized in combination with parent structures created by the process of nanosphere lithography to produce arrays of metal features with 10 nm spacings. Since our original report, we have improved the throughput and reproducibility of the molecular ruler process by automating its iterative nature and by utilizing appropriate chemical lift-off solutions. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer

Approach to critical dimension error budget analysis and specification estimation by the Monte Carlo method

Sung-Woo Lee, Gi-Sung Yeo, Jung-Hyeon Lee, Han-Ku Cho, and Woo-Sung Han

J. Vac. Sci. Technol. B 21, 3120 (2003); http://dx.doi.org/10.1116/1.1622945 (4 pages) | Cited 4 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A systematic approach to determine the specifications for process latitude in a 80 nm node device is suggested based on critical dimension (CD) error budget analysis using the Monte Carlo method. Using an aerial image simulation with the Gaussian convolution model, CD error budget analysis is performed on line/space (L/S), island, and contact patterns in a 90 nm node device. The portions contributed by mask uniformity are 60%, 66%, and 50% for the L/S, island, and contact patterns, respectively, and they occupy a dominant part in comparison with ones from other factors. The contact pattern occupies 12% for focus variation, which shows the larger portion than the analysis result for L/S and island patterns. The contribution of the 1 nm grid size in the mask layout is approximately 10% of the in-field uniformity. The residual terms which include variations from aberration, inaccurate measurement, postexposure baking, development, line-edge roughness, etc. occupy 21% for L/S and contact patterns, and 16% for island patterns. Based on CD error budget analysis, specifications in a 80 nm node device are calculated. The portion contributed by each process variation in the 80 nm node device is assumed to be approximately equal to those in the 90 nm node device. The specifications for mask uniformity are 6.8 and 5.8 nm for L/S and island patterns, respectively, while they are 2.9 nm for the contact pattern. The small margin for the contact pattern is due to a large mask error enhancement factor. The contact pattern shows a drastic decrease in flare, focus margin, illumination uniformity, and mask transmittance. In the 80 nm node device, the grid size of the mask layout to generate the patterns should be reduced to less than 0.3 nm. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
81.16.Rf Micro- and nanoscale pattern formation
02.70.Uu Applications of Monte Carlo methods

Line edge roughness of sub-100 nm dense and isolated features: Experimental study

Yuansheng Ma, G. Tsvid, and Franco Cerrina

J. Vac. Sci. Technol. B 21, 3124 (2003); http://dx.doi.org/10.1116/1.1624254 (7 pages) | Cited 14 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The nanoscale roughness in patterned images has become a crucial problem in advanced lithography. We have designed and implemented an experiment to study the line edge roughness (LER) for both dense line and space (DEN) and isolated (ISO) lines. The resist selected is UV-6 (a positive tone chemically amplified resist (CAR) from Shipley), and as a comparison, non-CAR such as poly(methylmethacrylate) (PMMA) is also measured. After development, the resist is analyzed using high resolution scanning electron microscopy (SEM) (LEO 1550 VP). An in-house made software is used for LER estimations. Our results indicate that DEN lines appear to be rougher than ISO lines given the same dose and nominal modulation. This is fully accounted by the lower modulation of DEN patterns caused by proximity effects. In addition, CAR resists like UV-6 are much rougher than non-CARs such as PMMA. A simple percolation model based on stochastic modeling predicts the observed trends. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer

Observations and measurements of photomasks using an electron beam with energy of 50 keV or higher

Fumio Mizuno, Takeshi Ohfuji, and Tsuyoshi Amano

J. Vac. Sci. Technol. B 21, 3131 (2003); http://dx.doi.org/10.1116/1.1624262 (5 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Applying a high-energy electron beam during photomask observations has been studied for improving resolution and reducing measurement uncertainty. Photomasks can be observed and measured by using an electron beam of 50 keV or higher in combination with a conductive coating over the photomask surfaces. Though image brightness and contrast vary with electron-beam exposure time, the effects of brightness and contrast on images are not significant and not essentially different from the effects with conventional low-energy electron beams. Therefore, a high-energy electron beam has the possibility of providing a higher measurement certainty than a conventional low-energy electron beam. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
07.78.+s Electron, positron, and ion microscopes; electron diffractometers

Picometer resolution measurement of the frequency spectrum of a periodic structure written by a MEBES electron beam pattern generator

Y. Jourlin, A. V. Tishchenko, C. Pedri, O. Parriaux, A. Zanzal, and J. Unruh

J. Vac. Sci. Technol. B 21, 3136 (2003); http://dx.doi.org/10.1116/1.1627797 (4 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A differential diffractive interferometric technique allows the high resolution retrieval of the spatial frequency profile along a long grating of supposedly constant period from the measurement of the phase of the two interference products detected by a double read head sensor upon its fly over the grating under test. The application of the technique to a 100 mm long grating written by a fifth generation MEBES e-beam writer reveals a maximum deviation of 2 pm from a nominal period of 1.070442 μm. © 2003 American Vacuum Society.
Show PACS
42.79.Dj Gratings
42.82.Cr Fabrication techniques; lithography, pattern transfer
42.87.-d Optical testing techniques
07.60.Ly Interferometers

Influence of gate patterning on line edge roughness

Leonardus H. A. Leunissen, Rik Jonckheere, Kurt Ronse, and Giljam B. Derksen

J. Vac. Sci. Technol. B 21, 3140 (2003); http://dx.doi.org/10.1116/1.1627799 (4 pages) | Cited 7 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
It is shown by simulation that the line edge roughness (LER) on the gates causes fluctuations on transistor performance [J. A. Croon et al., “Line edge roughness: Characterization, modeling, and impact on device behavior,” Proceedings of the IEDM, 2002; “Experimental investigation of the impact of line-edge roughness on MOSFET performance and yield” (to be published)]. Efforts are underway to investigate the influence on device performance experimentally. In this article, the transfer of the LER of the resist pattern into the poly silicon layer is investigated. For the experimental setup isolated gate lines ranging between 50–180 nm were patterned with an e-beam lithography. The resist line patterns are generated with some additional programmed LER. After the e-beam lithography step the processing was continued with etching the poly-Si, resist strip, and SiON removal. Using an offline software analysis tool for the edge detection based on SEM pictures, it was possible to determine the influence of processing on both types of roughness. The analysis shows that the LER pattern is transferred to a large extent into the poly-Si. The 3σ-value roughness is influenced only slightly. The linewidth decreases approximately 10 nm between the two measurements (after litho and etch). This result is confirmed by linewidth measurements on a CD-SEM. An additional numerical study shows that the high frequency LER (period of a few nm) is smoothed out as the etching decreases the linewidth and thus erases small bumps. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
85.30.Tv Field effect devices
81.65.Cf Surface cleaning, etching, patterning
42.30.Sy Pattern recognition
68.37.Hk Scanning electron microscopy (SEM) (including EBIC)

Fabrication of trilayer resist using photocuring-imprint lithography

Sang Hoon Kim, H. Hiroshima, S. Inoue, Y. Kurashima, and M. Komuro

J. Vac. Sci. Technol. B 21, 3144 (2003); http://dx.doi.org/10.1116/1.1630330 (5 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We fabricated fine trilayer resist structures (photocurable polymer/spin-on-glass (SOG)/Novolak resist) with a smooth-top surface and low-edge roughness, which is useful for standard patterning for the evaluation of critical dimension-atomic-force microscopy using photocuring-imprint lithography. A very serious pattern shrinkage problem observed at the top of the photocurable polymer after etching at room temperature was greatly improved by using substrate cooling, where the temperature was decreased to −120 °C. Finally, we obtained improved pattern shrinkage of the photocurable polymer, ranging from a maximum of 23 nm to a minimum of 4 nm, at optimum etching conditions. The pattern reduction did not occur in the following etch process. From this result, we noticed that throughout the trilayer resist etch process, the pattern reduction was mainly generated in the photocurable polymer etching step. SOG was used as the hard mask. The SOG showed high etch selectivity against the bottom layer of the Novolak resist in O2-based plasmas. The SOG etched only in pure SF6 gas, but the SOG was not etched in O2-based plasmas. Novolak resist etching at room temperature showed very small pattern shrinkage, no residue, no undercut, and fine features, while the Novolak etching at −120 °C showed much residue and damaged etch profiles. It is probable that in contrast to −120 °C, at room temperature, the residue of the Novolak resist was clearly removed by the reactive species, which are activated by the increased temperature. After trilayer resist etching, removal of the SOG layer was needed for the measurement of the pattern shrinkage and the line-edge roughness (LER). In this experiment, the SOG layer was removed by using anhydrous hydrofluoric acid. This method did not cause the pattern collapse which is frequently found in wet etching removal. Furthermore, trilayer resist patterns after the removal of the SOG layer showed very fine etch profiles, and the LER variation was very small through the whole trilayer resist etching process. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning
68.37.Ps Atomic force microscopy (AFM)
82.35.Gh Polymers on surfaces; adhesion
52.77.Bn Etching and cleaning
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
back to top Resists

Relation between spatial resolution and reaction mechanism of chemically amplified resists for electron beam lithography

Takahiro Kozawa, Akinori Saeki, Atsuro Nakano, Yoichi Yoshida, and Seiichi Tagawa

J. Vac. Sci. Technol. B 21, 3149 (2003); http://dx.doi.org/10.1116/1.1619959 (4 pages) | Cited 37 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The generation of acids in chemically amplified electron beam resists needs the cation radicals of base polymer and electrons, both of which are generated via the ionization of base polymer on the exposure. This leads to the separation of several nanometers between protons and counter anions. The separation deserves special attention from the viewpoint of resolution blur. The distribution of counter anions was examined with a simulation based on the Smoluchowski equation. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Near edge x-ray absorption fine structure measurements of the interface between bottom antireflective coatings and a model deprotected photoresist

Erin L. Jablonski, Sharadha Sambasivan, Eric K. Lin, Daniel A. Fischer, Chelladurai Devadoss, and Rama Puligadda

J. Vac. Sci. Technol. B 21, 3153 (2003); http://dx.doi.org/10.1116/1.1621661 (4 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The interface between bottom anti-reflective coatings (BARCs) and a model deprotected photoresist, poly(4-hydroxystyrene) (PHS), was investigated using near edge x-ray absorption fine structure spectroscopy to identify mechanisms responsible for pattern degradation at the BARC/photoresist interface. Interactions at this interface can lead to pattern deviations such as footing, undercut, and pattern collapse. It was found that a residual layer is only formed when the bilayer is subject to ultraviolet exposure. The spectra of the BARC surfaces after photoresist processing and development show a combination of spectral features from both PHS and the BARC formulations. The data suggest that the residual layer results from interactions between crosslinker and photoresist that occur during normal photoresist processing. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
78.70.Dm X-ray absorption spectra
68.35.Fx Diffusion; interface formation
42.79.Wc Optical coatings
68.35.Dv Composition, segregation; defects and impurities

Electron beam lithography process using radiation sensitive carboxylate metalorganic precursors

Augustin Jeyakumar, Clifford L. Henderson, Paul Roman, and Seigi Suh

J. Vac. Sci. Technol. B 21, 3157 (2003); http://dx.doi.org/10.1116/1.1624250 (5 pages) | Cited 4 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
A bilayer process has been developed for electron beam lithography using radiation sensitive metalorganic precursors as imaging layers in conjunction with organic planarizing layers. Upon electron beam irradiation, the precursor is converted to a metal oxide which serves as an etch mask for subsequent pattern transfer through the planarizing layer. In this article, a titanium(n-butoxide)2(2-ethylhexanoate)2 precursor was investigated that exhibits sensitivity and contrast of 495 μC/cm2 and 2.75, respectively, 10 keV accelerating potential. The sensitivity was further enhanced to 72 μC/cm2 using a pre-exposure thermal bake to partially convert the precursor to metal oxide prior to electron beam imaging. Additionally, it was found that combining the titanium(n-butoxide)2(2-ethylhexanoate)2 precursor with a similar precursor containing a higher atomic number metal center, barium(2-ethylhexanoate)2 in this work, also enhanced the sensitivity to 157 μC/cm2 for a 1:1 molar mixture of the precursors. After imaging and development, the patterns were completely converted to metal oxide by thermal baking to improve the etch resistance of the hard mask. This postdevelopment thermal conversion step was found to result in vertical shrinkage of the features and minimal lateral shrinkage. For bilayer processing, the titanium precursor was imaged on top of hard baked novolac and the pattern was transferred through the novolac using an O2 reactive ion etch. Sub-100 nm patterning is demonstrated using both single layer and bilayer processes with these materials, with aspect ratios greater than five achieved with the bilayer process. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography
81.16.Rf Micro- and nanoscale pattern formation
81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning

Near edge x-ray absorption fine structure measurements of surface segregation in 157 nm photoresist blends

Erin L. Jablonski, Vivek M. Prabhu, Sharadha Sambasivan, Eric K. Lin, Daniel A. Fischer, Dario L. Goldfarb, Marie Angelopoulos, and Hiroshi Ito

J. Vac. Sci. Technol. B 21, 3162 (2003); http://dx.doi.org/10.1116/1.1624256 (4 pages) | Cited 3 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
The surface and bulk chemistry of photoresist blends for use at the 157 nm node were analyzed using near edge x-ray absorption fine structure spectroscopy to quantify component segregation and identify surface phenomena that may impact pattern formation. Spectral combinations of the constituent polymers are used to fit the spectra of the blend films. Significant segregation of one component to the surface of the photoresist film was found, in excess of the composition of that component in the blend. The bulk data were consistent with initial blend compositions. As expected, the more hydrophobic or lower surface tension component wets the film surface even under typical photoresist processing conditions. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
68.35.Dv Composition, segregation; defects and impurities
78.70.Dm X-ray absorption spectra

Stochastic modeling of high energy lithographies

Geng Han, Mumit Khan, and Franco Cerrina

J. Vac. Sci. Technol. B 21, 3166 (2003); http://dx.doi.org/10.1116/1.1627798 (6 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
We present our progress in developing a comprehensive stochastic model that taking into account the energy redistribution from the incoming radiation, the location of the chemical events, the type of chemical changes, and the resist development. A study of line edge roughness extracted from the simulation for 50 nm lines is discussed. © 2003 American Vacuum Society.
Show PACS
81.16.Nd Micro- and nanolithography
85.40.Hp Lithography, masks and pattern transfer
81.16.Rf Micro- and nanoscale pattern formation
02.50.Ey Stochastic processes

Statistical limitations of printing 50 and 80 nm contact holes by EUV lithography

G. M. Gallatin, F. A. Houle, and J. L. Cobb

J. Vac. Sci. Technol. B 21, 3172 (2003); http://dx.doi.org/10.1116/1.1629294 (5 pages) | Cited 8 times

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
Nanoscale photolithography requires accurate formation of very small resist images using high energy photons and a high sensitivity resist. Historically it has been presumed that the primary technical challenges for design of a photoresist that will image with high accuracy under these conditions are shot noise effects, i.e., statistical variation of overall photon intensity from place to place on the wafer, and line-edge roughness. While these issues have been examined to various degrees, other aspects of the resist response have not received comparable attention. These include the effect of the statistics of the chemical reactions during post-expose bake and dissolution on resist images, and the effect of the fluctuations of the spatial distribution of photons within a printed feature. In order to examine the impact of all of these we have carried out a series of simulations of resist image formation as a function of dose for arrays of 50 and 80 nm contact holes printed with EUV (13.4 nm) radiation using an experimentally validated reaction-diffusion model that mimics ESCAP-class photoresists. The results show that intensity and spatial fluctuations of the light as well as simple variations in the local chemistry all affect contact size. The simulations indicate that the degree of precision contemplated for printed nanoscale features will require an extraordinary level of control over the resist chemistry and processing. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

Monitor and control for development technology

S. Ito and K. Hayasaki

J. Vac. Sci. Technol. B 21, 3177 (2003); http://dx.doi.org/10.1116/1.1629716 (4 pages)

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
One consequence of the expected shift to low-k1 lithography is the existence of many process fluctuations that make the control of the development processes increasingly important. To control the critical dimension uniformity in the wafer, a low-impact dispensing method for developer was investigated. During the development, the dissolution status is measured as the change of the zeroth order diffracted lights at monitor pattern. This article discusses the best dispense-nozzle-scan condition of a low-impact dispense nozzle and accuracy of the monitor-control-development process that controls according to the change of the zeroth order diffracted lights. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.16.Nd Micro- and nanolithography

High transparency resists for 157 nm lithography

Toshiro Itani, Seiichi Ishikawa, Shigeo Irie, and Takuya Hagiwara

J. Vac. Sci. Technol. B 21, 3181 (2003); http://dx.doi.org/10.1116/1.1630328 (5 pages) | Cited 1 time

Online Publication Date: 10 December 2003

Full Text: Read Online (HTML) | Download PDF

Show Abstract
157 nm lithography resist based on monocyclic fluorinated polymer with a blocking group of cyclohexylcyclohexanoxymethyl (CCOM) was developed. The transmittance was more than 70% at the resist thickness of 200 nm that corresponds to the absorption coefficient of 0.80 μm−1 at a 157 nm exposure wavelength. The dry-etching rate was improved 1.75 times that of the KrF resist based on polyhydroxystyrene under the conditions of fluorocarbon-based plasma oxide etching. Furthermore, this resist has higher dissolution rate contrast compared with the polymers with the other blocking groups that we evaluated. The resolution limit of 55 nm lines and spaces pattern was obtained using a 150 nm resist thickness. We found that this monocyclic fluorinated polymer with a blocking group of CCOM simultaneously enabled higher transparency, higher dry-etching resistance, and superior imaging performance. © 2003 American Vacuum Society.
Show PACS
85.40.Hp Lithography, masks and pattern transfer
81.65.Cf Surface cleaning, etching, patterning
Close

Your Recent History Recent History Help

Recently Viewed

  1. Metal contacts on semiconductors: The adsorption of Sb, Sn, and Ga on InP(110) cleaved surfaces
  2. Classical stochastic diffusion theory for thermal desorption from solid surfaces
  3. Single cell detection with micromechanical oscillators
  4. Step and flash imprint lithography: Template surface treatment and defect analysis
  5. Field emission properties of carbon nanotubes
© 2012 AVS Science & Technology of Materials, Interfaces, and Processing Help | Contact
close