Browse - Journal of Vacuum Science & Technology A

Select this Article

Two-photon absorption laser induced fluorescence on O and O₃ in a dc plasma for oxidation of aluminum

K. Knechten, B. J. Kniknie, R. Engeln, H. J. M. Swagten, B. Koopmans, M. C. M. van de Sanden, and W. J. M. de Jonge

J. Vac. Sci. Technol. A 22, L11 (2004); http://dx.doi.org/10.1116/1.1807837 (4 pages)

Online Publication Date: 20 October 2004

Full Text: Read Online (HTML) | Download PDF

+

Show Abstract

It has been conjectured that atomic oxygen and ozone can have a great influence on the plasma oxidation of ultrathin aluminum for magnetic tunnel junctions. In order to measure the density of O and ozone, two-photon absorption laser induced fluorescence measurements are performed in the dc glow plasma that is used for the oxidation process. It was found that ozone is much more abundantly present compared to atomic oxygen. Using in situ, real-time ellipsometry measurements, we prove that ozone is not directly involved in the oxidation process.

+

Show PACS

52.70.Kz	Optical (ultraviolet, visible, infrared) measurements
52.80.Hc	Glow; corona
82.33.Xj	Plasma reactions (including flowing afterglow and electric discharges)
81.65.Mq	Oxidation

Select this Article

Real-time wetting dynamics and interfacial chemistry in low-melting 57Bi–42Sn–1Ag solder paste on Ni–Au

M. J. Bozack

J. Vac. Sci. Technol. A 22, 2223 (2004); http://dx.doi.org/10.1116/1.1789212 (11 pages)

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

We report the observation of real-time, in situ, wetting and spreading dynamics for 57Bi–42Sn–1Ag solder paste on Ni–Au surfaces during melting in a scanning electron microscope. The 57Bi–42Sn–1Ag is a low melting (139 °C) Pb-free eutectic alloy currently under consideration by automobile manufacturers for use in instrument displays. We find that, while there is excellent wetting of 57Bi–42Sn–1Ag solder paste on Ni–Au, there is almost no spreading. A large amount of Bi segregates to the surface of 57Bi–42Sn–1Ag solder balls during the sintering process. At melting, excessive flux outgassing and pooling are observed, several melted solder balls float on top of the flux, and substantial elemental segregation occurs during the first minutes of wetting. Neither Ni nor Au fully intermixes throughout the alloy at the interface within seconds of wetting. Bi does not move outward with the expanding alloy front. This combination of detrimental effects forms voids in the solder paste, contributes to low reliability of solder joints, and complicates the materials science at the solder-substrate interface as shown by Auger electron spectroscopy. Reliability work in progress (3000 cycles) shows that 57Bi–42Sn–1Ag on Ni–Au is less reliable than eutectic Sn–37Pb on Ni–Au for 2512 chip resistors cycled from −40 to 125 °C.

+

Show PACS

82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces
68.08.Bc	Wetting
64.75.-g	Phase equilibria
68.37.Hk	Scanning electron microscopy (SEM) (including EBIC)
79.20.Fv	Electron impact: Auger emission
64.70.D-	Solid-liquid transitions
61.72.Qq	Microscopic defects (voids, inclusions, etc.)

Select this Article

GeO₂-doped SiO₂ sputtered thin films: Microstructure, stoichiometry, and optical properties

E. Quartarone, P. Mustarelli, F. Marabelli, M. Battagliarin, and S. Turato

J. Vac. Sci. Technol. A 22, 2234 (2004); http://dx.doi.org/10.1116/1.1789213 (5 pages) | Cited 2 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

Radio frequency sputtering is a reliable and low-cost technique for the deposition of oxide thin films. Here we report on the nonreactive preparation of SiO₂ and SiO₂–GeO₂ films, which can be of interest in optics and optoelectronics. The deposition rate of SiO₂–GeO₂ is roughly three times higher than that of SiO₂. Secondary ion mass spectroscopy shows SiO nonstoichiometry in SiO₂ films, and the formation of Ge or Ge-based defects in SiO₂–GeO₂ samples. The best fits of the ellipsometric spectra confirm the nonstoichiometry of SiO₂ films, showing that SiO fraction (and the refractive index, n) tends to decrease by increasing the deposition time.

+

Show PACS

81.15.Cd	Deposition by sputtering
81.05.Kf	Glasses (including metallic glasses)
78.66.Jg	Amorphous semiconductors; glasses
78.20.Ci	Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
61.43.Fs	Glasses
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
68.55.Nq	Composition and phase identification
68.55.-a	Thin film structure and morphology

Select this Article

Reactions of ultrathin hard amorphous carbon (a-C) films under microbeam laser processing

Li Hong Zhang, Hao Gong, Yuan Qing Li, and Jian Ping Wang

J. Vac. Sci. Technol. A 22, 2239 (2004); http://dx.doi.org/10.1116/1.1789214 (7 pages)

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

The decomposition mechanism of hard a-C films under irradiation using a microbeam laser (514.5 nm) was studied. The films were magnetron sputtered at different pressures to achieve different degrees of sp³∕sp² bonding ratio. Under laser irradiation, they showed graphitization and decomposition. The graphitization saturated at early exposure of ∼4 min, while the decomposition progressed exponentially with the exposure time, following a first-order reaction mechanism. The decomposition of a-C films under laser irradiation can be modeled using a two-step process with the establishment of a quasi steady-state intermediate. The relative energy barrier and rate constant for film decomposition were calculated. With increasing sp³∕sp² bonding ratio, the films showed increasing resistance against the irradiation-induced changes. This is shown by the decreasing rate constant and increasing energy barrier during the decomposition.

+

Show PACS

61.43.Er	Other amorphous solids
68.55.-a	Thin film structure and morphology
81.15.Cd	Deposition by sputtering
61.80.Ba	Ultraviolet, visible, and infrared radiation effects (including laser radiation)
79.20.Ds	Laser-beam impact phenomena
64.75.-g	Phase equilibria
81.05.U-	Carbon/carbon-based materials
61.50.Lt	Crystal binding; cohesive energy
42.62.-b	Laser applications

Select this Article

Boron surfactant enhanced growth of thin Si films on CaF₂∕Si

C. R. Wang, B. H. Müller, E. Bugiel, T. Wietler, M. Bierkandt, K. R. Hofmann, and P. Zaumseil

J. Vac. Sci. Technol. A 22, 2246 (2004); http://dx.doi.org/10.1116/1.1789215 (5 pages) | Cited 7 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

Boron surfactant enhanced solid-phase epitaxy (SPE) of thin Si films on CaF₂∕Si(111) substrates has been studied. Two different growth processes were investigated. In the first process, 1 ML of boron atoms was predeposited on the CaF₂ surface at room temperature before Si evaporation followed by an anneal to 635 °C. This resulted in Si cluster formation. The surface morphology of the Si layer did not show any improvement compared to SPE without surfactant. In the second process, boron atoms were deposited directly on top of the amorphous Si film. This resulted in continuous and smooth epitaxial Si layers on CaF₂ with a sharp B-induced ( math

×

)R30° surface reconstruction after annealing.

+

Show PACS

68.55.-a	Thin film structure and morphology
61.43.Dq	Amorphous semiconductors, metals, and alloys
68.35.B-	Structure of clean surfaces (and surface reconstruction)
81.05.Gc	Amorphous semiconductors
81.40.Gh	Other heat and thermomechanical treatments

Select this Article

Origin of H⁻ in collisions of hydrogen atoms with an adsorbate-covered Cu(100) surface

J. N. DeFazio and B. L. Peko

J. Vac. Sci. Technol. A 22, 2251 (2004); http://dx.doi.org/10.1116/1.1795821 (5 pages)

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

Results are presented from an experimental study of electron capture and loss during collisions of low-energy hydrogen atoms and ions with a residual gas covered metal surface. Ground-state hydrogen atoms (H 1s) and the atomic ions (H⁻,H⁺) were scattered from a Cu(100) surface with energies ranging from 25 to 200 eV. Energy loss analysis indicates that the dominant process leading to H⁻ formation proceeds directly through the adsorbed vacuum species, with the metallic crystal acting primarily as a physical scattering platform. In addition, ion beam experiments reveal effects due to the charge state of the incident particle that are inconsistent with the results expected for clean metal surfaces. Measurements indicate that the neutralization of incident ions as expected for clean metals is suppressed, a feature that is attributed to the band gap and dielectric strength of the adsorbed layer.

+

Show PACS

68.43.-h	Chemisorption/physisorption: adsorbates on surfaces
61.80.Jh	Ion radiation effects
71.20.-b	Electron density of states and band structure of crystalline solids
77.22.Jp	Dielectric breakdown and space-charge effects

Select this Article

Bulk and interface charge in low temperature silicon nitride for thin film transistors on plastic substrates

Kie Jin Park and Gregory N. Parsons

J. Vac. Sci. Technol. A 22, 2256 (2004); http://dx.doi.org/10.1116/1.1795822 (5 pages) | Cited 6 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

We report bulk and interface charge densities in silicon nitride thin films deposited by plasma chemical vapor deposition from NH₃–N₂–SiH₄ mixtures, at temperatures compatible with flexible plastic substrates. Bulk and interface charges are independently determined from measurements of flat band potential as a function of film thickness for a range of substrate temperatures and gas compositions. Increasing NH–SiH bond ratio in the deposited films (determined from infrared absorption) leads to a more positive interface charge and more negative bulk charge, and the trend in interface charge is consistent with a relation between charge and stress at the Si–SiN_x interface. As substrate temperature is decreased from 250 to 50 °C, the leakage is observed to decrease, the interface charge decreases, and the bulk charge changes from negative to net positive.

+

Show PACS

73.40.-c	Electronic transport in interface structures
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Li	Other semiconductors
78.30.Hv	Other nonmetallic inorganics
81.05.Hd	Other semiconductors

Select this Article

Silicide formation at HfO₂–Si and ZrO₂–Si interfaces induced by Ar⁺ ion bombardment

Yuri Lebedinskii and Andrei Zenkevich

J. Vac. Sci. Technol. A 22, 2261 (2004); http://dx.doi.org/10.1116/1.1795823 (4 pages) | Cited 8 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

The effect of ion bombardment with Ar⁺ at several keV energy ranges resulting in silicide formation at HfO₂–Si and ZrO₂–Si interfaces has been investigated in situ with x-ray photoelectron spectroscopy. The set of spectra recorded during the growth of thin HfO₂ and ZrO₂ layers on Si(100) was compared to those obtained during subsequent sputtering with an Ar⁺ beam. It is shown that the Ar⁺ ion beam affects the MeO₂–Si (Me=Hf,Zr) interface at thickness ⩽3 nm, inducing the formation of a silicide layer ∼2 nm in thickness. The proposed mechanism of silicide formation including the depletion of the interface in oxygen due to its preferential sputtering and subsequent Hf–Si intermixing is corroborated by computer simulations.

+

Show PACS

61.80.Jh	Ion radiation effects
79.60.Jv	Interfaces; heterostructures; nanostructures
81.05.Hd	Other semiconductors

Select this Article

Suboxide characteristics in ultrathin oxides grown under novel oxidation processes

Yen-Po Lin and Jenn-Gwo Hwu

J. Vac. Sci. Technol. A 22, 2265 (2004); http://dx.doi.org/10.1116/1.1795824 (8 pages) | Cited 2 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

Interfacial suboxide (SiO_x,0<x<2) between Si and its stable SiO₂ is observed to be a key factor to affect the ultrathin-oxide quality. SiO₂ grown by anodic oxidation (anodization) or by repeated-spike oxidation (RSO) presents a better dielectric characteristic than conventional rapid-thermal oxidation (RTO). This improvement can be attributed to two reasons: (1) A thinner transition region and/or (2) more stoichiometric S–O bonds under the same oxide thickness. Anodic SiO₂ presents a thinner suboxide width (interface region) and RSO SiO₂ demonstrates the existence of less suboxide existence at the near-surface region (oxide bulk). The reduction of the imperfect bonding structure in suboxide gives an abrupt Si–SiO₂ interface and consequently, the reduction of electron tunneling probability through oxide.

+

Show PACS

77.22.-d	Dielectric properties of solids and liquids
81.65.Mq	Oxidation
61.50.Lt	Crystal binding; cohesive energy

Select this Article

Smoothing of (111) oriented Cu films by post-deposition in situ 20–100 eV Ar ion bombardment

J. C. S. Kools and A. J. Devasahayam

J. Vac. Sci. Technol. A 22, 2273 (2004); http://dx.doi.org/10.1116/1.1795825 (3 pages) | Cited 2 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

We have studied the effect of low energy (20–100 eV) Ar bombardment on the surface roughness of (111) oriented Cu films both experimentally and by molecular-dynamics simulations. We found, in good agreement between the experiments and the simulations, that a significant reduction of the surface roughness can be induced at all energies in this range. However, the angle of incidence for optimal smoothing depends strongly on the ion energy, whereby the lower energies used are more efficient at near normal incidence, and the higher energies are more efficient for off-normal angles (e.g., >45 degrees).

+

Show PACS

68.47.De	Metallic surfaces
68.35.B-	Structure of clean surfaces (and surface reconstruction)
61.80.Jh	Ion radiation effects

Select this Article

Etching with electron beam generated plasmas

D. Leonhardt, S. G. Walton, C. Muratore, R. F. Fernsler, and R. A. Meger

J. Vac. Sci. Technol. A 22, 2276 (2004); http://dx.doi.org/10.1116/1.1795827 (8 pages) | Cited 5 times

Online Publication Date: 7 October 2004

Full Text: | Download PDF

+

Show Abstract

A modulated electron beam generated plasma has been used to dry etch standard photoresist materials and silicon. Oxygen–argon mixtures were used to etch organic resist material and sulfur hexafluoride mixed with argon or oxygen was used for the silicon etching. Etch rates and anisotropy were determined with respect to gas compositions, incident ion energy (from an applied rf bias) and plasma duty factor. For 1818 negative resist and i-line resists the removal rate increased nearly linearly with ion energy (up to 220 nm∕min at 100 eV), with reasonable anisotropic pattern transfer above 50 eV. Little change in etch rate was seen as gas composition went from pure oxygen to 70% argon, implying the resist removal mechanism in this system required the additional energy supplied by the ions. With silicon substrates at room temperature, mixtures of argon and sulfur hexafluoride etched approximately seven times faster (1375 nm∕min) than mixtures of oxygen and sulfur hexafluoride (∼200 nm∕min) with 200 eV ions, the difference is attributed to the passivation of the silicon by involatile silicon oxyfluoride (SiO_xF_y) compounds. At low incident ion energies, the Ar–SF₆ mixtures showed a strong chemical (lateral) etch component before an ion-assisted regime, which started at ∼75 eV. Etch rates were independent of the 0.5%–50% duty factors studied in this work.

+

Show PACS

52.77.Bn	Etching and cleaning
81.65.Cf	Surface cleaning, etching, patterning
81.65.Rv	Passivation
85.40.Hp	Lithography, masks and pattern transfer

Select this Article

Micro-Auger electron spectroscopy studies of chemical and electronic effects at GaN-sapphire interfaces

X. L. Sun, S. T. Bradley, G. H. Jessen, D. C. Look, R. J. Molnar, and L. J. Brillson

J. Vac. Sci. Technol. A 22, 2284 (2004); http://dx.doi.org/10.1116/1.1795820 (6 pages)

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

We have used cross-sectional micro-Auger electron spectroscopy (AES), coupled with micro-cathodoluminescence (CLS) spectroscopy, in a UHV scanning electron microscope to probe the chemical and related electronic features of hydride vapor phase epitaxy GaN/sapphire interfaces on a nanometer scale. AES images reveal dramatic evidence for micron-scale diffusion of O from Al₂O₃ into GaN. Conversely, plateau concentrations of N can extend microns into the sapphire, corresponding spatially to a 3.8 eV defect emission and Auger chemical shifts attributed to Al-N-O complexes. Interface Al Auger signals extending into GaN indicates AlGaN alloy formation, consistent with a blue-shifted CLS local interface emission. The widths of such interface transition regions range from <100 nm to ∼1 μm, depending on surface pretreatment and growth conditions. Secondary ion mass spectroscopy depth profiles confirm the elemental character and spatial extent of diffusion revealed by micro-AES, showing that cross-sectional AES is a useful approach to probe interdiffusion and electronic properties at buried interfaces.

+

Show PACS

82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.20.Fv	Electron impact: Auger emission
66.30.Ny	Chemical interdiffusion; diffusion barriers
81.05.Ea	III-V semiconductors
78.60.Hk	Cathodoluminescence, ionoluminescence
68.55.A-	Nucleation and growth
81.15.Kk	Vapor phase epitaxy; growth from vapor phase
78.66.Fd	III-V semiconductors
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)

Select this Article

Monte Carlo sensitivity analysis of CF₂ and CF radical densities in a c‐C₄F₈ plasma

Deepak Bose, Shahid Rauf, D. B. Hash, T. R. Govindan, and M. Meyyappan

J. Vac. Sci. Technol. A 22, 2290 (2004); http://dx.doi.org/10.1116/1.1795826 (9 pages) | Cited 3 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A Monte Carlo sensitivity analysis is used to build a plasma chemistry model for octacyclofluorobutane (c‐C₄F₈) which is commonly used in dielectric etch. Experimental data are used both quantitatively and qualitatively to analyze the gas phase and gas surface reactions for neutral radical chemistry. The sensitivity data of the resulting model identifies a few critical gas phase and surface aided reactions that account for most of the uncertainty in the CF₂ and CF radical densities. Electron impact dissociation of small radicals (CF₂ and CF) and their surface recombination reactions are found to be the rate-limiting steps in the neutral radical chemistry. The relative rates for these electron impact dissociation and surface recombination reactions are also suggested. The resulting mechanism is able to explain the measurements of CF₂ and CF densities available in the literature and also their hollow spatial density profiles.

+

Show PACS

52.65.Pp	Monte Carlo methods
52.25.Vy	Impurities in plasmas
82.33.Xj	Plasma reactions (including flowing afterglow and electric discharges)
52.25.-b	Plasma properties

Select this Article

Evolution of local texture and grain morphology in metal plasma immersion ion implantation & deposition of TiN

D. Manova, W. Attenberger, S. Mändl, B. Stritzker, and B. Rauschenbach

J. Vac. Sci. Technol. A 22, 2299 (2004); http://dx.doi.org/10.1116/1.1795828 (7 pages)

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

The local crystallographic texture and grain orientation was investigated for deposition of TiN by metal plasma immersion ion implantation & deposition (MePIIID) at different ion incident angles across one sample. A very good match between the tilt of (fiber) texture and the tilt of grains was observed, indicating the validity of models for ion beam assisted deposition (IBAD) also for MePIIID. A (100) orientation was obtained for 5 kV pulses at 9% duty cycle. The ion incident angle changed from near normal at the center towards 35° tilt away from the surface normal at the sample edge for the substrate orientation at 45° towards the cathode. However, due to the pulsed regime in MePIIID, there exist certain differences from IBAD.

+

Show PACS

68.55.-a	Thin film structure and morphology
68.35.B-	Structure of clean surfaces (and surface reconstruction)
52.77.Dq	Plasma-based ion implantation and deposition
81.15.Jj	Ion and electron beam-assisted deposition; ion plating

Select this Article

Simple energy spike model for paracrystalline silicon in ion implantation

Ju-Yin Cheng and J. M. Gibson

J. Vac. Sci. Technol. A 22, 2306 (2004); http://dx.doi.org/10.1116/1.1795829 (5 pages) | Cited 1 time

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A simple energy spike model is used to interpret the experimental results of medium-range order in ion-implanted amorphous silicon. This model can justify the liquid state, which is speculated to be the initial state of paracrystalline silicon in ion implantation. According to this model, we hypothesize that a crystallite is produced from the hottest spot of a liquid state. As solidification to an amorphous state proceeds from the boundary, the central spot undergoes the maximum undercooling. Such a condition can induce homogeneous crystallization, but it is not possible to form a perfect crystal therein. One can envisage that the spike finally becomes a paracrystallite. In support of the theory, we provide the key equations of the model in this article. But this model still needs to be verified by computer simulations in the future.

+

Show PACS

61.43.Dq	Amorphous semiconductors, metals, and alloys
64.70.D-	Solid-liquid transitions

Select this Article

Measurements of desorbed products by plasma beam irradiation on SiO₂

Kazuaki Kurihara, Yoshikazu Yamaoka, Kazuhiro Karahashi, and Makoto Sekine

J. Vac. Sci. Technol. A 22, 2311 (2004); http://dx.doi.org/10.1116/1.1795830 (4 pages) | Cited 9 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A plasma beam irradiation apparatus with a controllable plasma source was constructed to investigate the plasma-surface interactions for reactive etching processes. The apparatus can control the plasma parameters, such as ion energy, radical∕ion composition, and the ratio of neutral to ion flux. The desorbed products of SiFx (x=1–3) were observed separately from COFx (x=1–3) by using a ¹³CF₄–Ar gas mixture plasma beam. The major desorbed product was not SiF₄. Unsaturated fluorinated silicons [SiFx (x=1–3)] were major desorbed products under ion-rich fluorocarbon plasma etching condition. It was found that the composition of silicon containing desorbed products does not depend on the incident ion energy in the ion energy range of 300–700 eV.

+

Show PACS

52.77.Bn	Etching and cleaning
68.43.Mn	Adsorption kinetics
52.40.Hf	Plasma-material interactions; boundary layer effects
81.65.Cf	Surface cleaning, etching, patterning

Select this Article

Effects of wetting ability of plating electrolyte on Cu seed layer for electroplated copper film

Chi-Wen Liu, Jung-Chih Tsao, Ming-Shih Tsai, and Ying-Lang Wang

J. Vac. Sci. Technol. A 22, 2315 (2004); http://dx.doi.org/10.1116/1.1795831 (6 pages) | Cited 5 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

This work examines the impact of the wetting ability of a plating electrolyte on the Cu seed layer on copper electroplating performance. The contact angle of the electrolyte on the Cu seed is highly sensitive to additive decomposition in the electrolyte, as well as being sensitive to Cu seed self-annealing. The contact angle of the electrolyte decreases in the presence of polyethylene glycol (PEG), which forms complexes with chloride ions and is absorbed on the Cu surface during plating. However, the consumption of the additives, particularly that of chloride ions, degrades this adsorption. Additionally, the increase in Cu-seed surface roughness owing to self-annealing also reduces electrolyte wettability, compared to the as-received Cu-seed layer. The poor wettability can be improved with additional rinsing. The x-ray photoelectron spectroscopy (XPS) spectrum demonstrates that the Cu surface was covered with a native cupric-hydroxide layer after rinsing, which was hydrophilic (as in the aqueous-plating bath) and had improved wettability. This study also correlates the contact angle with the trapped defects in the electroplated film, which in turn influence the electrical characteristics of the interconnection. The experimental results show that the poor wettability of the plating electrolyte on the Cu seed significantly influences the fluctuations of the Cu interconnect resistance. This conclusion is valuable in designing Cu damascene processes.

+

Show PACS

82.45.Gj	Electrolytes
81.15.Pq	Electrodeposition, electroplating
68.43.Mn	Adsorption kinetics
79.60.Bm	Clean metal, semiconductor, and insulator surfaces
81.40.Gh	Other heat and thermomechanical treatments
73.61.At	Metal and metallic alloys
68.35.-p	Solid surfaces and solid-solid interfaces: structure and energetics
64.75.-g	Phase equilibria

Select this Article

Effects of thermal annealing on the structural, mechanical, and tribological properties of hard fluorinated carbon films deposited by plasma enhanced chemical vapor deposition

M. E. H. Maia da Costa, I. J. R. Baumvol, C. Radke, L. G. Jacobsohn, R. R. M. Zamora, and F. L. Freire

J. Vac. Sci. Technol. A 22, 2321 (2004); http://dx.doi.org/10.1116/1.1795833 (8 pages) | Cited 2 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Hard amorphous fluorinated carbon films (a-C:F) deposited by plasma enhanced chemical vapor deposition were annealed in vacuum for 30 min in the temperature range of 200–600 °C. The structural and compositional modifications were followed by several analytical techniques: Rutherford backscattering spectrometry (RBS), elastic recoil detection analysis (ERDA), x-ray photoelectron spectroscopy (XPS) and Raman spectroscopy. Nanoidentation measurements and lateral force microscopy experiments were carried out in order to provide the film hardness and the friction coefficient, respectively. The internal stress and contact angle were also measured. RBS, ERDA, and XPS results indicate that both fluorine and hydrogen losses occur for annealing temperatures higher than 300 °C. Raman spectroscopy shows a progressive graphitization upon annealing, while the surface became slightly more hydrophobic as revealed by the increase of the contact angle. Following the surface wettability reduction, a decrease of the friction coefficient was observed. These results highlight the influence of the capillary condensation on the nanoscale friction. The film hardness and the internal stress are constant up to 300 °C and decrease for higher annealing temperatures, showing a direct correlation with the atomic density of the films. Since the thickness variation is negligible, the mass loss upon thermal treatment results in amorphous structures with a lower degree of cross-linking, explaining the deterioration of the mechanical properties of the a-C:F films.

+

Show PACS

68.60.Bs	Mechanical and acoustical properties
81.40.Gh	Other heat and thermomechanical treatments
81.40.Pq	Friction, lubrication, and wear
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
68.55.A-	Nucleation and growth
52.77.Dq	Plasma-based ion implantation and deposition
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
79.60.Dp	Adsorbed layers and thin films
78.30.Hv	Other nonmetallic inorganics
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
68.43.Mn	Adsorption kinetics
62.20.Qp	Friction, tribology, and hardness
62.20.M-	Structural failure of materials
68.35.Dv	Composition, segregation; defects and impurities
68.47.-b	Solid-gas/vacuum interfaces: types of surfaces

Select this Article

Effect of pressure on the deposition of hydrogen-free amorphous carbon and carbon nitride films by the pulsed cathodic arc discharge method

Dongping Liu, Günther Benstetter, Wenchun Wang, and Jialiang Zhang

J. Vac. Sci. Technol. A 22, 2329 (2004); http://dx.doi.org/10.1116/1.1798691 (7 pages)

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Hydrogen-free amorphous carbon (a-C) and carbon nitride (a-C:N) films were deposited using the pulsed cathodic arc discharge at different argon and nitrogen pressures. The surface and mechanical properties of these films were found to strongly depend on the gas pressure. The tetrahedral amorphous carbon and hard a-C:N films with smooth surfaces (rms roughness: 0.15 nm) were prepared at lower gas pressures (<6×10⁻² Pa). Incorporation of an increasing amount of nitrogen in a-C:N films caused a decrease in film hardness. All the films were covered with the thin (0.3–2 nm) graphite-like surface layers. The film hardness was correlated to the soft surface layer thickness, and the films with thinner surface layers exhibit higher hardness. The mean energies of pulsed plasma beams were measured as the functions of argon and nitrogen pressures. The mean energies of plasma beams decrease in an exponential fashion with increasing gas pressure due to the carbon ion collisions with the neutral gas species. The effects of mean energies of deposited species on the film deposition were explained in terms of the thermal spike migration of surface atoms. The formation of graphite-like surface layers is associated with the low-energy deposition process. The low-energy (<1–3 eV) species diffusing on film surface lead to the formation of graphite-like a-C films with plenty of grains. The higher-energy (>10 eV) species may produce the strong thermal spike at film surface, and contribute to the formation of sp³ bonded structure at a sp³ bonded matrix.

+

Show PACS

81.15.Jj	Ion and electron beam-assisted deposition; ion plating
68.55.A-	Nucleation and growth
68.55.-a	Thin film structure and morphology
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp	Friction, tribology, and hardness
68.35.Gy	Mechanical properties; surface strains
52.77.Dq	Plasma-based ion implantation and deposition
68.60.-p	Physical properties of thin films, nonelectronic
68.35.Fx	Diffusion; interface formation
81.05.U-	Carbon/carbon-based materials

Select this Article

Influence of cathode material and SiCl₄ gas on inductively coupled plasma etching of AlGaN layers with Cl₂∕Ar plasma

Evgeny Zhirnov, Sergei Stepanov, Wang Nang Wang, Y. G. Shreter, D. V. Takhin, and N. I. Bochkareva

J. Vac. Sci. Technol. A 22, 2336 (2004); http://dx.doi.org/10.1116/1.1798711 (6 pages) | Cited 6 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

The influence of cathode coverplate material on inductively coupled plasma etching of GaN and AlGaN with 1% and 10% of Al was investigated. It was revealed that coverplate material has a great impact on the etching of Al-containing layers. Results obtained with a graphite coverplate and a Si wafer on top of a quartz coverplate indicate that etch products of coverplate material such as SiCl_x, CCl_x reactive species and SiClx+, CClx+ ions play a significant role in fast and smooth etching of Al-containing layers. They act as getters to remove oxygen in the process chamber and as effective etchers for oxide layers formed by background oxygen in the process chamber. Experiments where SiCl₄ gas was added to Cl₂∕Ar plasma confirmed the role of SiCl_x reactive species and SiClx+ ions for fast and smooth etching of AlGaN layers.

+

Show PACS

81.65.Cf	Surface cleaning, etching, patterning
52.77.Bn	Etching and cleaning
81.05.Ea	III-V semiconductors

Select this Article

Amorphous silicon nitride films of different composition deposited at room temperature by pulsed glow discharge plasma immersion ion implantation and deposition

I. V. Afanasyev-Charkin, L. G. Jacobsohn, R. D. Averitt, and M. Nastasi

J. Vac. Sci. Technol. A 22, 2342 (2004); http://dx.doi.org/10.1116/1.1798731 (5 pages) | Cited 4 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Amorphous hydrogenated silicon nitride (a-SiN_x:H) films of different compositions (0⩽x⩽1.18) were prepared by pulsed glow discharge plasma immersion ion implantation and deposition. The processing gases were silane and nitrogen at a substrate temperature ⩽50 °C. The properties of the films were investigated using Rutherford backscattering, elastic recoil detection analysis, UV–visible optical absorption, Fourier transform infrared, and Raman spectroscopies, and nanoindentation. Depending on the value of x, the band gap of the films changes from 1.54 to 4.42 eV, and hardness changes from 11.2 to 15.3 GPa. Changes in the film properties are caused by formation of Si–N bonds and by reducing disorder in the films. It is shown that hard and transparent silicon nitride films can be obtained at room temperature.

+

Show PACS

81.15.Jj	Ion and electron beam-assisted deposition; ion plating
68.55.A-	Nucleation and growth
52.77.Dq	Plasma-based ion implantation and deposition
78.35.+c	Brillouin and Rayleigh scattering; other light scattering
78.40.Pg	Disordered solids
68.35.Gy	Mechanical properties; surface strains
78.66.Nk	Insulators
81.05.-t	Specific materials: fabrication, treatment, testing, and analysis
61.50.Lt	Crystal binding; cohesive energy
61.43.Er	Other amorphous solids
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.Qp	Friction, tribology, and hardness

Select this Article

Detection of quasimolecular ion of Cu(hfac)(tmvs) by ion attachment mass spectrometry

Megumi Nakamura, Yoshiro Shiokawa, Toshihiro Fujii, Masao Takayanagi, and Munetaka Nakata

J. Vac. Sci. Technol. A 22, 2347 (2004); http://dx.doi.org/10.1116/1.1798751 (4 pages) | Cited 4 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A molecular ion of (trimethylvinylsilane)(1,1,1,5,5,5-hexafluoroacetyl-acetonato)Cu(I) [Cu(hfac)(tmvs)], which could not be detected by mass spectrometry with conventional ionization techniques such as electron impact ionization because of weak coordination bonds, has been successfully detected as a quasimolecular ion, Cu(hfac)(tmvs)Li⁺, for the first time by recently developed ion-attachment mass spectrometry (IAMS). Cu(hfac)(tmvs) is a material widely used in the metal organic chemical vapor deposition (MOCVD) process. In the thermal decomposition of Cu(hfac)(tmvs), trimethylvinylsilane (tmvs) and hexafluoroacetylacetone (Hhfac) were observed by IAMS as the reaction products. We also evaluated the dependence of the decomposition process on temperature. We found IAMS to be an effective tool in monitoring and clarifying MOCVD processes.

+

Show PACS

33.15.Ta	Mass spectra
82.30.Lp	Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Select this Article

Structure and mechanical properties of Ti–Si–N films deposited by combined DC/RF reactive unbalanced magnetron sputtering

X. Z. Ding, X. T. Zeng, Y. C. Liu, Q. Yang, and L. R. Zhao

J. Vac. Sci. Technol. A 22, 2351 (2004); http://dx.doi.org/10.1116/1.1798771 (5 pages) | Cited 9 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Ti–Si–N nanocomposite films with Si content between 0 and 13.5 at. % were deposited by combined DC/RF reactive unbalanced magnetron sputtering. The composition, structure, and mechanical properties of the as-deposited Ti–Si–N films were measured by energy dispersive analysis of x rays, x-ray diffraction (XRD), and nanoindentation experiments, respectively. All of the Ti–Si–N films exhibited a higher hardness than pure TiN films deposited under similar conditions. The highest hardness (∼41 GPa) was obtained in the film with Si content of about 8 at. %. Ti–Si–N films also exhibited a higher resistance to plastic deformation (i.e., higher ratio H³∕E*²) than pure TiN. XRD patterns revealed that the as-deposited films were composed of cubic TiN crystallites with a preferential orientation of (111). With increase of RF power applied to the Si targets, the TiN (111) peak intensity or TiN crystallite size increased in the lower RF power range but decreased in the higher RF power range, showing a maximum at an RF power of 500 W (power density ∼1.14 W∕cm²), corresponding to a Si content of about 5 at. % in the film.

+

Show PACS

68.55.-a	Thin film structure and morphology
68.55.A-	Nucleation and growth
68.60.Bs	Mechanical and acoustical properties
81.15.Cd	Deposition by sputtering
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
81.40.Lm	Deformation, plasticity, and creep
62.20.M-	Structural failure of materials
62.20.Qp	Friction, tribology, and hardness
62.20.F-	Deformation and plasticity
82.80.Ej	X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
68.35.Dv	Composition, segregation; defects and impurities
68.47.-b	Solid-gas/vacuum interfaces: types of surfaces

Select this Article

Improvement of electrochemical properties in LiCoO₂ cathode films grown on Pt∕TiO₂∕SiO₂∕Si substrates by liquid-delivery metalorganic chemical vapor deposition

Woon-Gi Choi and Soon-Gil Yoon

J. Vac. Sci. Technol. A 22, 2356 (2004); http://dx.doi.org/10.1116/1.1798791 (5 pages) | Cited 3 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

The structural and electrochemical properties of LiCoO₂ cathode films grown on Pt∕TiO₂∕SiO₂∕Si substrates at 500 °C by liquid-delivery metalorganic chemical vapor deposition (LDMOCVD) were investigated as a function of Li∕Co mol ratio. The electrochemical properties such as initial discharge capacity and cyclic retention were improved through the study of Raman spectra of as-grown and annealed LiCoO₂ films. The deposition temperature of 500 °C was chosen to characterize the films because films grown at 500 °C showed a typical high temperature hexagonal phase without Co₃O₄ impurities in the films. The optimum annealing condition of as-grown samples with Li∕Co=2.0 and 3.0 was at 700 °C for 30 min in an oxygen ambient. The highest initial discharge capacity and capacity retention were obtained in Li∥LiCoO₂ cells grown with Li∕Co=3.0 and 2.0, respectively, and were approximately 38 μA h cm⁻² μm and 77%, respectively. The compositional window for an optimum electrochemical property exists in the range of Li∕Co=2.0 to 3.0 in an as-grown temperature of 500 °C and annealing temperature of 700 °C for 30 min in O₂.

+

Show PACS

82.45.Fk	Electrodes
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk	Vapor phase epitaxy; growth from vapor phase
78.30.Hv	Other nonmetallic inorganics
81.40.Gh	Other heat and thermomechanical treatments
82.47.Aa	Lithium-ion batteries
78.66.-w	Optical properties of specific thin films
81.05.-t	Specific materials: fabrication, treatment, testing, and analysis

Select this Article

Current-pressure characteristics of planar magnetron discharges in rare gases

M. L. Escrivão, P. J. S. Pereira, M. H. Cabral, M. R. Teixeira, and M. J. P. Maneira

J. Vac. Sci. Technol. A 22, 2361 (2004); http://dx.doi.org/10.1116/1.1804982 (4 pages)

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

The variation of current intensity with pressure, at constant voltage, (I-p characteristics), was obtained for planar magnetron discharges in neon, krypton, and xenon on a copper target. The analysis of those curves confirms that an equation of the same type as the one recently obtained by the authors for an argon–copper discharge is an adequate relation to describe the dependence of current intensity on pressure and voltage for planar magnetron discharges in rare gases. That equation accounts for a bimodal behavior corresponding to the sum of a “magnetron term” and a “diode term.”

+

Show PACS

52.80.-s

Electric discharges

Select this Article

In situ x-ray diffraction observation of multiple texture turnovers in sputtered Cr films

Z. B. Zhao, Z. U. Rek, S. M. Yalisove, and J. C. Bilello

J. Vac. Sci. Technol. A 22, 2365 (2004); http://dx.doi.org/10.1116/1.1804984 (8 pages)

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A series of Cr films were deposited onto native oxides of (100) Si substrates via a confocal deposition geometry in a magnetron sputter chamber. The film growth chamber was incorporated with an in situ x-ray diffraction system, which allowed the collection of x-ray diffraction data on the growing film in a quasi real time fashion without interruption of film deposition. The in situ x-ray diffraction, coupled with other ex situ characterization techniques, was used to study structural evolutions of the Cr films deposited at various Ar pressures. It was observed that the evolution of the crystallographic structures of Cr films was very sensitive to both deposition conditions and film thickness. With the confocal deposition geometry, the Cr films developed various types of out-of-plane textures. In addition to the (110) and (100) types of textures commonly reported for vapor deposited Cr films, the (111) and (112) types of textures were also observed. The film deposited at low Ar pressure (2 mTorr) developed strong (111) type texture. With the increase in either Ar pressure or film thickness, the Cr films tended to develop (112) and (100) types of texture. At high Ar pressures (>10 mTorr), several changes in texture type with increasing film thickness were observed. The sequence can be described as (110)→(112)→(100). The strong tendency for these films to ultimately assume the (100) type of texture could be related to significant rises in substrate temperatures during the late stages of film growth with high Ar pressures. The observation of the multiple texture type changes suggests that the evolution of Cr films is controlled by complex growth kinetics. The competitive growth of grains with different orientations can be altered not only by controllable deposition parameters such as Ar pressure, but also by the variations of in situ film attributes (e.g., residual stress and substrate temperature) occurring concurrently with film growth.

+

Show PACS

68.55.A-	Nucleation and growth
68.55.-a	Thin film structure and morphology
81.15.Cd	Deposition by sputtering
68.60.Bs	Mechanical and acoustical properties
81.05.Bx	Metals, semimetals, and alloys
68.47.De	Metallic surfaces

Select this Article

Characteristics of organic film deposited by plasma-enhanced chemical-vapor deposition using a benzocyclobutene resin

Suehiro Sugitani, Hideaki Matsuzaki, and Takatomo Enoki

J. Vac. Sci. Technol. A 22, 2373 (2004); http://dx.doi.org/10.1116/1.1806438 (6 pages) | Cited 1 time

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Characteristics of organic film deposited by plasma-enhanced chemical-vapor deposition (CVD) at temperatures below 250 °C using a liquid source of benzocyclobutene (BCB) resin were investigated and compared with standard spin-coated BCB film. CVD film with a thickness of 0.3 μm was successfully deposited on a 3 in. wafer with a thickness uniformity of 3%. The dielectric constant, breakdown voltage, stress, and moisture absorption of the CVD film are similar to those of spin-coated film. However, using Fourier transform infrared spectroscopy, Auger electron spectroscopy, and pyrolysis gas chromatography/mass spectroscopy, it was found that the CVD film has almost no methyl-siloxane, which exists in spin-coated film. Therefore, CVD film can be etched by reactive-ion etching using only O₂ gas. The step-coverage of the CVD film is conformal and considered advantageous for use in ultrafine structures.

+

Show PACS

77.55.-g	Dielectric thin films
77.84.Jd	Polymers; organic compounds
77.22.Jp	Dielectric breakdown and space-charge effects
78.30.Jw	Organic compounds, polymers
77.22.Ch	Permittivity (dielectric function)
68.55.-a	Thin film structure and morphology
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
85.40.Sz	Deposition technology
81.65.Cf	Surface cleaning, etching, patterning

Select this Article

Electron trapping in metal-insulator-semiconductor structures on n-GaN with SiO₂ and Si₃N₄ dielectrics

Choelhwyi Bae, Cristiano Krug, and Gerald Lucovsky

J. Vac. Sci. Technol. A 22, 2379 (2004); http://dx.doi.org/10.1116/1.1806439 (5 pages) | Cited 5 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Electron trapping in Al-gate n-GaN∕nitrided-thin-Ga₂O₃∕SiO₂ and n-GaN∕Si₃N₄ MIS capacitors was evaluated by capacitance-voltage (C–V) measurements. Significant positive flatband voltage shift (ΔV_fb) was observed with increasing starting dc bias in the C–V measurements. For similar equivalent oxide thickness and under the same C–V measurement conditions, ΔV_fb in the nitride was 3–10 times larger than in the oxide samples. It is suggested that flatband voltage shifts are due to border traps in SiO₂ and to interface and bulk traps in Si₃N₄ samples.

+

Show PACS

73.50.Gr	Charge carriers: generation, recombination, lifetime, trapping, mean free paths
84.32.Tt	Capacitors
73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
85.30.Tv	Field effect devices

Select this Article

Novel rubidium atomic beam with an alkali dispenser source

Timothy M. Roach and Dwayne Henclewood

J. Vac. Sci. Technol. A 22, 2384 (2004); http://dx.doi.org/10.1116/1.1806440 (4 pages) | Cited 4 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

We describe a novel atomic beam apparatus with a resistively heated alkali dispenser source and a cold-pumped intermediate chamber. Using laser fluorescence spectroscopy we have measured the atomic density to be 3×10¹¹ atoms∕m³ and the total flux to be 5×10⁸ atoms∕s in a 0.3 cm diameter beam. We have also characterized the velocity distribution of the source based on the Doppler-shifted fluorescence spectrum. The compact geometry, flexibility, and simplicity of the beam may make it useful as an optical frequency reference or for experiments on atom-cooling.

+

Show PACS

37.20.+j	Atomic and molecular beam sources and techniques
32.50.+d	Fluorescence, phosphorescence (including quenching)
06.20.F-	Units and standards
37.10.De	Atom cooling methods
37.10.Gh	Atom traps and guides
42.62.Eh	Metrological applications; optical frequency synthesizers for precision spectroscopy
32.80.Xx	Level crossing and optical pumping

Select this Article

Dry etching of NiFe∕Co and NiFe∕Al–O∕Co multilayers in an inductively coupled plasma of Cl₂∕Ar mixture

H.-W. Ra, Y. B. Hahn, K. S. Song, M. H. Park, and Y. K. Hong

J. Vac. Sci. Technol. A 22, 2388 (2004); http://dx.doi.org/10.1116/1.1806441 (4 pages) | Cited 6 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Dry etching of NiFe∕Co and NiFe∕Al–O∕Co multilayers was carried out in inductively coupled Cl₂∕Ar plasmas. An ion-enhanced etch mechanism took a critical role for desorption of chlorine etch products. NiFe∕Al–O∕Co showed a faster etch rate than NiFe∕Co at various etch conditions. Anisotropic and smooth features were obtained using a photoresist mask. Sidewall contamination with etch products was observed at a higher Cl₂ concentration (>50%). Postetch cleaning of the etched samples in deionized water reduced the chlorine residues substantially.

+

Show PACS

81.65.Cf	Surface cleaning, etching, patterning
52.77.Bn	Etching and cleaning
68.65.Ac	Multilayers
75.70.Cn	Magnetic properties of interfaces (multilayers, superlattices, heterostructures)
68.43.Mn	Adsorption kinetics

Select this Article

Infrared spectroscopic study of atomic layer deposition mechanism for hafnium silicate thin films using HfCl₂[N(SiMe₃)₂]₂ and H₂O

Sang-Woo Kang, Shi-Woo Rhee, and Steven M. George

J. Vac. Sci. Technol. A 22, 2392 (2004); http://dx.doi.org/10.1116/1.1806442 (6 pages) | Cited 10 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

In situ Fourier transform infrared (FT-IR) spectroscopy was used to study the atomic layer deposition mechanism of hafnium silicate films with dichlorobis[bis(trimethylsilyl)amido] hafnium (HfCl₂[N(SiMe₃)₂]₂) and water. The surface species was monitored during atomic layer deposition using vacuum chambers designed for in situ FT-IR spectroscopy studies. Vibrational spectroscopy reveals the gain and loss of surface species during the two surface half-reactions. The behavior of the functional group (such as O–Η, Si–(CH₃)_x, and C–H was monitored and from that, the temperature dependence of the growth rate and the film composition could be explained. It was also found that Si–O–Si peaks between 1000 and 1200 cm⁻¹ were formed when water was dosed above 300°C, which could explain the incorporation mechanism of Si into the film.

+

Show PACS

78.30.Jw	Organic compounds, polymers
68.55.-a	Thin film structure and morphology
81.15.-z	Methods of deposition of films and coatings; film growth and epitaxy
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.05.-t	Specific materials: fabrication, treatment, testing, and analysis

Select this Article

Room temperature preparation of activated and crystallized p-type Si_1−xGe_x thin film on glass substrate by intense, pulsed, ion beam evaporation

M. Hirai, R. Iwashita, T. Arikado, H. Suematsu, W. Jiang, K. Yatsui, M. Takeda, and N. Uchitomi

J. Vac. Sci. Technol. A 22, 2398 (2004); http://dx.doi.org/10.1116/1.1807393 (4 pages) | Cited 2 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A boron doped Si_1−xGe_x thin film has been successfully prepared on a quartz (SiO₂) glass substrate at room temperature (RT) by irradiating an intense, pulsed, ion beam on a Si–Ge–B pellet. As a result, in situ boron doped Si_1−xGe_x thin film was found to be crystallized. In addition, by van der Pauw measurement, the resistivity, carrier density, and mobility of the thin film were observed as ρ=2.3×10⁻³ Ω cm, n=7.2×10²⁰ cm⁻³, and μ=3.8 cm²∕Vs, respectively. Thus, the boron doped Si_1−xGe_x thin film was clarified to be not only crystallized but also activated without heat treatment.

+

Show PACS

73.61.Le	Other inorganic semiconductors
73.50.Bk	General theory, scattering mechanisms
72.80.Jc	Other crystalline inorganic semiconductors

Select this Article

Low-temperature preparation of GaN-SiO₂ interfaces with low defect density. I. Two-step remote plasma-assisted oxidation-deposition process

Choelhwyi Bae and Gerald Lucovsky

J. Vac. Sci. Technol. A 22, 2402 (2004); http://dx.doi.org/10.1116/1.1807396 (9 pages) | Cited 5 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

In previous studies, device-quality Si-SiO₂ interfaces and dielectric bulk films (SiO₂) were prepared using a two-step process: (i) remote plasma-assisted oxidation (RPAO) to form a superficially interfacial oxide (∼0.6 nm) and (ii) remote plasma-enhanced chemical vapor deposition (RPECVD) to deposit the oxide film. The same approach has been applied to the GaN-SiO₂ system. Without an RPAO step, subcutaneous oxidation of GaN takes place during RPECVD deposition of SiO₂, and on-line Auger electron spectroscopy indicates a ∼0.7-nm subcutaneous oxide. The quality of the interface and dielectric layer with/without RPAO process has been investigated by fabricated GaN metal-oxide-semiconductor capacitors. Compared to single-step SiO₂ deposition, significantly reduced defect state densities are obtained at the GaN-SiO₂ interface by independent control of GaN-GaO_x interface formation by RPAO and SiO₂ deposition by RPECVD.

+

Show PACS

81.65.Mq	Oxidation
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Dq	Plasma-based ion implantation and deposition
85.30.Tv	Field effect devices
73.20.Hb	Impurity and defect levels; energy states of adsorbed species
68.55.A-	Nucleation and growth
71.55.Eq	III-V semiconductors
81.05.Ea	III-V semiconductors
77.55.-g	Dielectric thin films
77.84.Bw	Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Select this Article

Low-temperature preparation of GaN-SiO₂ interfaces with low defect density. II. Remote plasma-assisted oxidation of GaN and nitrogen incorporation

Choelhwyi Bae and Gerald Lucovsky

J. Vac. Sci. Technol. A 22, 2411 (2004); http://dx.doi.org/10.1116/1.1807411 (8 pages) | Cited 1 time

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

Low-temperature remote plasma-assisted oxidation and nitridation processes for interface formation and passivation have been extended from Si and SiC to GaN. The initial oxidation kinetics and chemical composition of thin interfacial oxide were determined from analysis of on-line Auger electron spectroscopy features associated with Ga, N, and O. The plasma-assisted oxidation process is self-limiting with power-law kinetics similar to those for the plasma-assisted oxidation of Si and SiC. Oxidation using O₂∕He plasma forms nearly pure GaO_x, and oxidation using 1% N₂O in N₂ forms GaO_xN_y with small nitrogen content, ∼4–7 at. %. The interface and dielectric layer quality was investigated using fabricated GaN metal-oxide-semiconductor capacitors. The lowest density of interface states was achieved with a two-step plasma-assisted oxidation and nitridation process before SiO₂ deposition.

+

Show PACS

81.65.Mq	Oxidation
81.05.Ea	III-V semiconductors
81.65.Lp	Surface hardening: nitridation, carburization, carbonitridation
81.65.Rv	Passivation
71.55.Eq	III-V semiconductors
73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
84.32.Tt	Capacitors
77.55.-g	Dielectric thin films
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
73.20.At	Surface states, band structure, electron density of states
52.77.-j	Plasma applications
73.61.Ey	III-V semiconductors
77.84.Bw	Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.

Select this Article

Preparation and characterization of high-quality TiN films at low temperature by filtered cathode arc plasma

Y. J. Zhang, P. X. Yan, Z. G. Wu, J. W. Xu, W. W. Zhang, X. Li, W. M. Liu, and Q. J. Xue

J. Vac. Sci. Technol. A 22, 2419 (2004); http://dx.doi.org/10.1116/1.1807836 (5 pages) | Cited 2 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

High-quality TiN films were successfully deposited on silicon and stainless-steel substrates at low temperature using an improved filtered cathode arc plasma technique developed in our lab. Atomic force microscope, x-ray diffractometer, x-ray photoelectron spectroscopy, and a nanoindenter were employed to characterize the TiN thin films. The microhardness of the TiN films have a high value up to 41 GPa, which is far higher than that of TiN compounds deposited by conventional chemical vapor deposition and physical vapor deposition methods (20 Gpa or so). The films are of a stronger preferred crystalline orientation, very smooth surface, and high reflectivity. The effects of the negative substrate bias on the preferred crystalline orientation, surface roughness, deposition rate, and microhardness of Tin thin films are discussed in detail.

+

Show PACS

68.60.Bs	Mechanical and acoustical properties
68.55.-a	Thin film structure and morphology
79.60.Bm	Clean metal, semiconductor, and insulator surfaces
68.37.Ps	Atomic force microscopy (AFM)
62.20.M-	Structural failure of materials
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
68.35.Gy	Mechanical properties; surface strains
62.20.Qp	Friction, tribology, and hardness
52.77.Dq	Plasma-based ion implantation and deposition
78.66.Db	Elemental semiconductors and insulators
79.60.Dp	Adsorbed layers and thin films
81.05.-t	Specific materials: fabrication, treatment, testing, and analysis
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Select this Article

Study of preferred orientation of zinc oxide films on the 64° LiNbO₃ substrates and their applications as liquid sensors

Shiou-Jen Jian, Sheng-Yuan Chu, Tung-Yi Huang, and Walter Water

J. Vac. Sci. Technol. A 22, 2424 (2004); http://dx.doi.org/10.1116/1.1809125 (7 pages) | Cited 3 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

The preferred (002) orientation of zinc oxide (ZnO) films has been grown and demonstrated on 64° LiNbO₃ substrates using a rf magnetron sputtering system. The film orientations and crystallinity are strongly dependent on the rf power, total chamber pressure, ratio of argon to oxygen, and substrate temperature. We investigated the crystalline structure of the films by x-ray diffraction and scanning electron microscopy. Highly oriented (002) films were obtained under a total chamber pressure of 1.33 Pa, containing 40% oxygen and 60% argon, and a substrate temperature around 120 °C. Love-wave devices based on this structure (ZnO∕IDTs∕64° LiNbO₃) are presented.

+

Show PACS

81.15.Cd	Deposition by sputtering
68.55.A-	Nucleation and growth
68.55.-a	Thin film structure and morphology
81.05.Dz	II-VI semiconductors
43.58.-e	Acoustical measurements and instrumentation
61.66.Fn	Inorganic compounds

Select this Article

Electron-cyclotron-resonance sputtering apparatus for multilayered optical bandpass filters applicable to wavelength division multiplexing

Yoshito Jin, Masaru Shimada, and Toshiro Ono

J. Vac. Sci. Technol. A 22, 2431 (2004); http://dx.doi.org/10.1116/1.1809128 (6 pages) | Cited 3 times

Online Publication Date: 20 October 2004

Full Text: | Download PDF

+

Show Abstract

A new apparatus for fabricating narrow-bandpass multilayer filters applicable to wavelength-division multiplexing and the development of this apparatus are described. Electron-cyclotron-resonance (ECR) sputtering with two plasma sources is used in the apparatus. The plasma is produced from a mixture of Ar and O₂ gas and, with a metallic target, generates stable “metal-mode” deposition. That is, the target is sputtered in a metallic state, and this is followed by oxide-film formation, which is enhanced by exposure of the substrate to the ECR plasma. SiO₂ and Ta₂O₅ films formed by ECR sputter-deposition in metal-mode are suitable for optical multilayer filters because this form of deposition provides surface smoothness, low loss, and stability of refractive index. Uniformity of deposition is good, with variations in thickness over a 200 mm diameter within ±0.43% for SiO₂ and ±0.27% for Ta₂O₅. The refractive indices of the SiO₂ and Ta₂O₅ films are 1.46 and 2.10 at a wavelength of 1550 nm. Surfaces are very smooth, with typical root-mean-square roughness values of only 0.13 nm for the Ta₂O₅ film and 0.19 nm for the SiO₂ film. We describe how we deposited multilayered structures consisting of 43 layers on an optical glass substrate, alternately SiO₂ and Ta₂O₅, and thus fabricated a narrow-band bandpass filter. We demonstrate a thin full width at half maximum of only 0.224 nm and bandpass filtering uniformity within ±0.1% over the whole 100 mm diameter substrate.

+

Show PACS

42.79.Ci	Filters, zone plates, and polarizers
42.79.Sz	Optical communication systems, multiplexers, and demultiplexers
81.15.Cd	Deposition by sputtering
68.55.A-	Nucleation and growth
68.55.-a	Thin film structure and morphology
81.05.-t	Specific materials: fabrication, treatment, testing, and analysis

Select this Article

In situ composition monitoring using reflection high-energy electron diffraction for SrTiO₃ thin films grown by reactive coevaporation

Luke S.-J. Peng and Brian H. Moeckly

J. Vac. Sci. Technol. A 22, 2437 (2004); http://dx.doi.org/10.1116/1.1809126 (3 pages) | Cited 1 time

Online Publication Date: 25 October 2004

Full Text: | Download PDF

+

Show Abstract

We have used in situ reflection high-energy electron diffraction (RHEED) to monitor the composition of SrTiO₃ (STO) thin films during growth by reactive coevaporation. This is accomplished through careful calibration of the relation between the Ti content and the STO lattice constant determined by RHEED. X-ray diffraction analysis of the films indicates that the rocking-curve and 2θ-scan peak widths of the STO (002) reflection are significantly improved after adopting this RHEED monitoring technique. This method thus results in improved epitaxial growth of STO thin films with reduced compositional fluctuations.

+

Show PACS

81.15.-z	Methods of deposition of films and coatings; film growth and epitaxy
77.55.-g	Dielectric thin films
68.55.A-	Nucleation and growth

Select this Article

Structure and electrical properties of MgTiO₃ thin films deposited by rf magnetron sputtering

Cheng-Liang Huang and Chung-Long Pan

J. Vac. Sci. Technol. A 22, 2440 (2004); http://dx.doi.org/10.1116/1.1810164 (6 pages) | Cited 2 times

Online Publication Date: 25 October 2004

Full Text: | Download PDF

+

Show Abstract

Bulk MgTiO₃ ceramics have shown excellent dielectric properties at microwave frequencies; however, the high sintering temperature of the bulk materials is major obstacle in their use as dielectric resonators to miniaturize microwave circuits. In this article, MgTiO₃ thin films were fabricated on n-type Si(100) substrates by rf magnetron sputtering by using MgTiO₃ target which was synthesized in the experiment. It was possible to obtain highly oriented MgTiO₃(110) thin film at a rf power density of 7.7 W∕cm² and a substrate temperature of 400 °C, which is much lower than the bulk sintering temperature. These films were studied by choosing different rf power densities and substrate temperature. The microstructure and surface morphology of the MgTiO₃ films deposited on Si(100) was determined by x-ray diffraction (XRD), scanning electron microscopy, and atomic force microscopy. The XRD showed that the deposited films exhibited a polycrystalline microstructure. The grain size of the film increased with an increase in the rf power density and substrate temperature. The electrical properties were measured using C-V and current-voltage I-V measurements on metal-insulator-semiconductor capacitor structures. As rf power density of 7.7 W∕cm² and substrate temperature of 400 °C, a dielectric constant of 14.9 (f=10 MHz) and a dissipation factor of 0.031 were obtained.

+

Show PACS

77.55.-g	Dielectric thin films
73.40.Qv	Metal-insulator-semiconductor structures (including semiconductor-to-insulator)
68.37.Ps	Atomic force microscopy (AFM)
77.84.Ek	Niobates and tantalates
77.84.Cg	PZT ceramics and other titanates
81.05.Je	Ceramics and refractories (including borides, carbides, hydrides, nitrides, oxides, and silicides)
81.05.Mh	Cermets, ceramic and refractory composites
77.22.Ch	Permittivity (dielectric function)
81.15.Cd	Deposition by sputtering

Select this Article

Low temperature epitaxy of reactively sputtered ZnO on sapphire

K. C. Ruthe, D. J. Cohen, and S. A. Barnett

J. Vac. Sci. Technol. A 22, 2446 (2004); http://dx.doi.org/10.1116/1.1807394 (7 pages) | Cited 6 times

Online Publication Date: 28 October 2004

Full Text: | Download PDF

+

Show Abstract

ZnO films were grown on c-plane sapphire by dc reactive magnetron sputtering. X-ray diffraction measurements showed that an epitaxial relationship of ZnO[10 math

0]‖Al₂O₃[11 math

0] and ZnO[2 math

0]‖Al₂O₃[1 math

00] was maintained down to a substrate temperature T_s≈80 °C, corresponding to <17% of the ZnO melting point. The low-temperature epitaxy was explained by the energetic species produced during sputtering and a high mobility of Zn surface atoms in low-oxygen conditions. Crystalline perfection improved with increasing T_s, decreasing growth rate, and decreasing oxygen-to-zinc flux ratio. Dense microstructures with flat surfaces were achieved at T_s≈200 °C, although at T_s≈80 °C films tended to transition to a columnar Zone 1 microstructure from a Zone T microstructure with increasing film thickness. In general, T_s=200–300 °C and an oxygen-to-zinc flux ratio of ≈300 yielded a favorable combination of good optical transparency, crystalline perfection, flat surfaces, and dense microstructure.

+

Show PACS

68.55.A-	Nucleation and growth
68.55.-a	Thin film structure and morphology
61.72.-y	Defects and impurities in crystals; microstructure
78.20.Ci	Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)

Select this Article

Growth and surface characterization of V₂O₅ thin films made by pulsed-laser deposition

C. V. Ramana, R. J. Smith, O. M. Hussain, and C. M. Julien

J. Vac. Sci. Technol. A 22, 2453 (2004); http://dx.doi.org/10.1116/1.1809123 (6 pages) | Cited 19 times

Online Publication Date: 28 October 2004

Full Text: | Download PDF

+

Show Abstract

V₂O₅ thin films were produced by pulsed laser deposition (PLD) over a wide temperature range, 30–500 °C. The effects of temperature and structural characteristics of the substrate on the growth, surface morphology, and local atomic structure of V₂O₅ films were probed with atomic force microscopy (AFM) and Raman spectroscopy (RS). The growth mode and microstructure evolution were strongly dependent on the substrate temperature. The onset of crystallization occurred at 200 °C with an activation energy of 0.43–0.55 eV. Polycrystalline PLD V₂O₅ films with layered structure exhibited the same local structural symmetry found in crystalline orthorhombic bulk V₂O₅.

+

Show PACS

81.15.Fg	Pulsed laser ablation deposition
68.55.-a	Thin film structure and morphology
68.37.Ps	Atomic force microscopy (AFM)
78.30.-j	Infrared and Raman spectra
78.66.-w	Optical properties of specific thin films
68.47.Gh	Oxide surfaces
81.05.-t	Specific materials: fabrication, treatment, testing, and analysis

Select this Article

Two-dimensional spatial survey of the plasma potential and electric field in a pulsed bipolar magnetron discharge

A. Vetushka, S. K. Karkari, and J. W. Bradley

J. Vac. Sci. Technol. A 22, 2459 (2004); http://dx.doi.org/10.1116/1.1810167 (10 pages) | Cited 20 times

Online Publication Date: 28 October 2004

Full Text: | Download PDF

+

Show Abstract

Emissive and Langmuir probe techniques have been used to obtain two-dimensional (2D) spatial maps of the plasma potential V_p, electric field E, and ion trajectories in a pulsed bipolar magnetron discharge. The magnetron was pulsed at a frequency of 100 kHz, with a 50% duty cycle and operated at an argon pressure of 0.74 Pa. The pulse wave form was characterized by three distinct phases: the “overshoot,” “reverse,” and “on” phases. In the “on” phase of the pulse, when the cathode voltage is driven to −670 V, the 2D spatial distribution of V_p has a similar form to that in dc magnetron, with significant axial and radial electric fields in the bulk plasma, accelerating ions to the sheath edge above the cathode racetrack region. During the “overshoot” phase (duration 200 ns), V_p is raised to values greater than +330 V, more than 100 V above the cathode potential, with E pointing away from the target. In the “reverse” phase V_p has a value of +45 V at all measured positions, 2 V more positive than the target potential. In this phase there is no electric field present in the plasma. In the bulk of the plasma, the results from Langmuir probe and the emissive probe are in good agreement, however, in one particular region of the plasma outside the radius of the cathode, the emissive probe measurements are consistently more positive (up to 45 V in the “on” time). This discrepancy is discussed in terms of the different frequency response of the probes and their perturbation of the plasma. A simple circuit model of the plasma-probe system has been proposed to explain our results. A brief discussion of the effect of the changing plasma potential distribution on the operation of the magnetron is given.

+

Show PACS

52.70.Ds	Electric and magnetic measurements
82.45.Fk	Electrodes
52.80.Hc	Glow; corona
52.77.Dq	Plasma-based ion implantation and deposition
81.15.Cd	Deposition by sputtering

Select this Article

Formation and analysis of disk-shaped grains by Ni-mediated crystallization of amorphous silicon

Kyung Ho Kim, Jae Hwan Oh, Eun Hyun Kim, and Jin Jang

J. Vac. Sci. Technol. A 22, 2469 (2004); http://dx.doi.org/10.1116/1.1810168 (4 pages) | Cited 2 times

Online Publication Date: 28 October 2004

Full Text: | Download PDF

+

Show Abstract

Disk- and needle-shaped grains can be seen in polycrystalline silicon (poly-Si) made by Ni-mediated crystallization of amorphous silicon (a-Si). A major parameter to give the difference of grain structure is the Ni area density on a-Si. However, there are many other parameters such as heating rate and structure of a-Si to affect the grain structure. The use of Ni density of ∼10¹³ cm⁻² on a-Si for the crystallization gives the disk-shaped grains. There is no amorphous phase in the disk-shaped grains which are composed of well-aligned needles. On the other hand, the poly-Si has some amorphous phase inside when it was crystallized into needlelike rods. It is found that the width of needles in the disk-shaped grains is smaller than that of needlelike crystallites. The Ni atoms are at the grain boundaries formed by the collisions of neighboring grains.

+

Show PACS

61.72.Mm	Grain and twin boundaries
64.70.K-	Solid-solid transitions
61.43.Dq	Amorphous semiconductors, metals, and alloys

Select this Article

Structure characterization and photon absorption analysis of carbon-doped β-FeSi₂ film

Xiaona Li, Dong Nie, Chuang Dong, Lei Xu, and Ze Zhang

J. Vac. Sci. Technol. A 22, 2473 (2004); http://dx.doi.org/10.1116/1.1795832 (6 pages) | Cited 2 times

Online Publication Date: 28 October 2004

Full Text: | Download PDF

+

Show Abstract

Carbon-doped β–FeSi₂ films synthesized by ion implantation are investigated with the aim to fabricate high-quality semiconducting β–FeSi₂ layer on silicon substrate. According to transmission electron microscopy (TEM) cross-section observations, carbon-doped films with homogeneous thickness and smooth β–Si interface, have higher quality than binary Fe–Si films. In particular, annealing at 500 °C–700 °C leads to the formation of a flat and continuous β-type silicide layer. Improved stability of the β phase is also found. Optical emission spectroscopy measurements show that the carbon doping influences only slightly the band gap values.

+

Show PACS

68.37.Lp	Transmission electron microscopy (TEM)
68.55.Ln	Defects and impurities: doping, implantation, distribution, concentration, etc.
78.66.Li	Other semiconductors
81.05.Hd	Other semiconductors

Select this Article

Near-infrared diode laser hydrogen fluoride monitor for dielectric etch

Ning Xu, David R. Pirkle, Jay B. Jeffries, Brian McMillin, and Ronald K. Hanson

J. Vac. Sci. Technol. A 22, 2479 (2004); http://dx.doi.org/10.1116/1.1809124 (8 pages) | Cited 2 times

Online Publication Date: 1 November 2004

Full Text: | Download PDF

+

Show Abstract

A hydrogen fluoride (HF) monitor, using a tunable diode laser, is designed and used to detect the etch endpoints for dielectric film etching in a commercial plasma reactor. The reactor plasma contains HF, a reaction product of feedstock gas CF₄ and the hydrogen-containing films (photoresist, SiOCH) on the substrate. A near-infrared diode laser is used to scan the P(3) transition in the first overtone of HF near 1.31 μm to monitor changes in the level of HF concentration in the plasma. Using 200 ms averaging and a signal modulation technique, we estimate a minimum detectable HF absorbance of 6×10⁻⁵ in the etch plasma, corresponding to an HF partial pressure of 0.03 mTorr. The sensor could indicate, in situ, the SiOCH over tetraethoxysilane oxide (TEOS) trench endpoint, which was not readily discerned by optical emission. These measurements demonstrate the feasibility of a real-time diode laser-based sensor for etch endpoint monitoring and a potential for process control.

+

Show PACS

81.65.Cf	Surface cleaning, etching, patterning
52.77.Bn	Etching and cleaning
85.40.Hp	Lithography, masks and pattern transfer
77.55.-g	Dielectric thin films

Select this Article

InN epitaxial growths on Yttria stabilized zirconia (111) step substrates

T. Honke, H. Fujioka, J. Ohta, and M. Oshima

J. Vac. Sci. Technol. A 22, 2487 (2004); http://dx.doi.org/10.1116/1.1809127 (3 pages) | Cited 9 times

Online Publication Date: 1 November 2004

Full Text: | Download PDF

+

Show Abstract

We have performed epitaxial growths of InN on Yttria stabilized zirconia (YSZ) (111) substrates which have steps and atomically flat terraces using pulsed laser deposition (PLD). The epitaxial relationship between InN and YSZ turns out to be InN [1 math

00]∕∕YSZ [1 math

0] and InN [000 math

]∕∕YSZ [111], which gives a small lattice mismatch of 2.3%. We have found that the full width at half maximum (FWHM) for the InN math

02

x-ray rocking curve is 980 arcseconds. Transmission electron microscopy (TEM) observations have revealed that the threading dislocation density in the InN films is less than 1×10⁹ cm⁻² and the InN∕YSZ hetero-interface is atomically abrupt. We have also found that the lattice relaxation starts from the beginning of the growth and ends at a film thickness of approximately 5 nm. After the lattice relaxation, the surface flatness is restored and the growth proceeds in the layer-by-layer mode.

+

Show PACS

68.55.A-	Nucleation and growth
81.15.Fg	Pulsed laser ablation deposition
68.55.-a	Thin film structure and morphology
81.05.Ea	III-V semiconductors
61.72.Ff	Direct observation of dislocations and other defects (etch pits, decoration, electron microscopy, x-ray topography, etc.)

Select this Article

Interface formation during the yttrium oxide deposition on Si by pulsed liquid-injection plasma enhanced metal-organic chemical vapor deposition

C. Durand, C. Vallée, C. Dubourdieu, E. Gautier, M. Bonvalot, and O. Joubert

J. Vac. Sci. Technol. A 22, 2490 (2004); http://dx.doi.org/10.1116/1.1810163 (10 pages) | Cited 3 times

Online Publication Date: 1 November 2004

Full Text: | Download PDF

+

Show Abstract

In this article, we investigate the main mechanisms of interfacial SiO₂ and silicate formation during yttrium oxide deposition on Si substrates by plasma-enhanced metal-organic chemical vapor deposition using a pulsed-liquid injection delivery source. The precursor supplier system is based on a sequential injection of Y-precursor diluted in an organic solvent. A detailed study of interface thickness and chemical nature is carried out combining angle-resolved x-ray photoelectron spectroscopy, transmission electron microscopy, and electron energy loss spectroscopy. We found that the flow rate of injected reactive species, controlled by the injection frequency, has a strong effect on the plasma gas phase and plays a key role in the SiO₂ and silicate formation. For a 1 Hz injection frequency deposition, a silicate layer is formed on a thick SiO₂ interface [Si∕SiO₂(∼3.6 nm)∕Si_xO_yY_z], whereas deposition at 5 Hz induces an oxidized yttrium layer with an interfacial layer composed of a SiO₂ and Y-silicate mixture [Si∕SiO₂+Si_xO_yY_z(∼2 nm)∕Y_xO_yC_z]. To understand the actual SiO₂ origin, the effect of the oxygen plasma on the silicon oxidation was investigated. According to our results, the silicon oxidation by the oxygen O* species from the plasma is strongly enhanced by the presence of organic compounds in the plasma gas phase from reactions between the solvent molecule and the oxygen. This reaction is mostly favored at a low solvent flow rate, which can explain the thicker SiO₂ layer observed for the 1 Hz sample compared to the 5 Hz. When introducing yttrium precursor in addition to the solvent, a Y-based silicate is formed via consumption of the SiO₂ by yttrium. The silicate formation is enhanced when a large quantity of SiO₂ is available, which is the case for the 1 Hz sample. According to this study, a high flow of reactive species is preferred to reduce the interface layer thickness.

+

Show PACS

68.35.Fx	Diffusion; interface formation
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
81.15.Kk	Vapor phase epitaxy; growth from vapor phase
82.33.Ya	Chemistry of MOCVD and other vapor deposition methods
81.65.Mq	Oxidation
52.77.Dq	Plasma-based ion implantation and deposition
66.30.Ny	Chemical interdiffusion; diffusion barriers

Select this Article

Investigation of fluorocarbon plasma deposition from c‐C₄F₈ for use as passivation during deep silicon etching

Catherine B. Labelle, Vincent M. Donnelly, Gregory R. Bogart, Robert L. Opila, and Avi Kornblit

J. Vac. Sci. Technol. A 22, 2500 (2004); http://dx.doi.org/10.1116/1.1810165 (8 pages) | Cited 9 times

Online Publication Date: 1 November 2004

Full Text: | Download PDF

+

Show Abstract

The passivation step used in the “Bosch” process (alternating etching and deposition steps) to perform deep anisotropic silicon etching has been examined in detail. The effect of pressure, inductively coupled plasma power, temperature, flow rate, and bias power on both deposition rate and film composition has been explored over a relatively wide range. Deposition rate was found to vary significantly as a function of temperature, power, and pressure. In contrast, only two film composition regimes were observed: high fluorine-to-carbon ratio (F:C) films (∼1.6) at low pressure∕high power versus low F:C films (∼1.2) at high pressure∕low power. Optical emission spectroscopy of the deposition plasmas also show only two regimes: C₂, C₃, and F emission dominated (high F:C films) and CF₂ emission dominated (low F:C films). A two-step deposition mechanism is assumed: carbon deposition followed by fluorination. Low F concentration and deposition from large fluorine-deficient C_xF_y species in the CF₂-rich plasmas result in the low F:C ratio films. Films deposited during an actual Bosch cycle generally mirror these bulk films, with slight differences. Analysis of etch:deposition rate ratios as a function of film F:C ratio indicates that, for the conditions studied here, a F:C ratio of 1.45 is optimal for Bosch processing (i.e., has the lowest etch:deposition rate ratio). Further analysis is needed to determine the effect of passivant F:C ratio on feature profiles.

+

Show PACS

52.77.Dq	Plasma-based ion implantation and deposition
81.65.Rv	Passivation
81.65.Cf	Surface cleaning, etching, patterning
68.55.A-	Nucleation and growth
68.55.-a	Thin film structure and morphology
78.30.Hv	Other nonmetallic inorganics
78.40.Ha	Other nonmetallic inorganics
78.66.-w	Optical properties of specific thin films
81.05.Lg	Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials

Select this Article

Vacuum beam studies of fluorocarbon radicals and argon ions on Si and SiO₂ surfaces

Yoshie Kimura, J. W. Coburn, and David B. Graves

J. Vac. Sci. Technol. A 22, 2508 (2004); http://dx.doi.org/10.1116/1.1810166 (9 pages) | Cited 5 times

Online Publication Date: 1 November 2004

Full Text: | Download PDF

+

Show Abstract

Si and SiO₂ were exposed to c-C₄F₈ with and without Ar⁺, and to a mixture of characterized C_xF_y radical and stable species with and without Ar⁺. The mixture of C_xF_y radical and stable species was created from c-C₄F₈ and Ar plasma and included CF, CF₂, CF₃, and various heavy C_xF_y species. The neutral fluorocarbon flux to Ar⁺ flux and the energy of the Ar⁺ were varied. During the exposure, etch/deposition rates were measured and the flux of C_xF_y species leaving the surface for various conditions were qualitatively determined. The following were observed: (1) c-C₄F₈ is an etchant with Ar⁺ bombardment; (2) the CF, CF₂, and CF₃ species flux cannot account for the observed mass increase during depositing conditions; (3) CF₂ and CF₃ species are net products during etching conditions; and (4) the flux of large C_xF_y species leaving the surface is smaller during etching conditions than for depositing conditions. These observations imply that large C_xF_y species play a significant role in the surface chemistry.

+

Show PACS

52.77.Bn	Etching and cleaning
52.77.Dq	Plasma-based ion implantation and deposition
52.40.Hf	Plasma-material interactions; boundary layer effects
81.65.Cf	Surface cleaning, etching, patterning

Select this Article

Prediction of SiC etching in a NF₃∕CH₄ plasma using neural network

Byungwhan Kim and Byung Teak Lee

J. Vac. Sci. Technol. A 22, 2517 (2004); http://dx.doi.org/10.1116/1.1810169 (6 pages) | Cited 6 times

Online Publication Date: 1 November 2004

Full Text: | Download PDF

+

Show Abstract

Silicon carbide (SiC) was etched in a NF₃∕CH₄ inductively coupled plasma. The etch process was modeled by using a neural network called generalized regression neural network (GRNN). For modeling, the process was characterized by a 2⁴ full factorial experiment with one center point. To test model appropriateness, additional test data of 16 experiments were conducted. The GRNN prediction performance was optimized by means of a genetic algorithm (GA). Compared to a conventional GRNN model, the GA-GRNN model demonstrated a significant improvement of more than 85%. Predicted model behaviors were highly consistent with actual measurements. From the GA-optimized model, several plots were predicted to examine etch mechanisms. The model predicted that parameter effects are a complex function of plasma conditions. The etch rate was strongly correlated to the variations in the pressure-induced dc bias. This was also illustrated for the variations in the gas ratio.

+

Show PACS

81.65.Cf	Surface cleaning, etching, patterning
52.77.Bn	Etching and cleaning
07.05.Mh	Neural networks, fuzzy logic, artificial intelligence

SECTION LISTING

BROWSE VOLUMES

Nov 2004

Volume 22, Issue 6, pp. L11-2522

Find articles by AUTHORNAME