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Mar 2004

Volume 22, Issue 2, pp. 227-441

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Comparison of pulsed and downstream deposition of fluorocarbon materials from C3F8 and c-C4F8 plasmas

Ina T. Martin, Galiya Sh. Malkov, Carmen I. Butoi, and Ellen R. Fisher

J. Vac. Sci. Technol. A 22, 227 (2004); http://dx.doi.org/10.1116/1.1638779 (9 pages) | Cited 27 times

Online Publication Date: 14 January 2004

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Materials deposited in continuous wave (cw) and pulsed low-pressure octafluoropropane (C3F8) and octafluorocyclobutane (c-C4F8) plasmas were characterized using Fourier transform infrared spectroscopy (FTIR), x-ray photoelectron spectroscopy, static contact angle measurements, spectroscopic ellipsometry, and scanning electron microscopy (SEM). Fluorocarbon (FC) materials deposited in pulsed plasmas were less crosslinked than those deposited in cw plasmas with equivalent input powers. Within each system, higher F/C ratio materials were deposited by lowering the plasma input power/duty cycle. Using downstream depositions had a similar effect on film composition, but also resulted in decreased deposition rates. SEM analysis showed that decreases in the flexibility of the fluorocarbon films were correlated with increases in the percent of crosslinking. Additionally, the smoothness of the film surfaces suggests that polymerization processes occur on the substrate surface. Overall, films deposited in C4F8 plasmas were more crosslinked and less flexible than those deposited in C3F8 plasmas under the same conditions. The composition of the deposited FC films is correlated to the nature and relative concentrations of nascent ions previously measured in these plasma systems using plasma ion mass spectrometry. © 2004 American Vacuum Society.
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52.77.Dq Plasma-based ion implantation and deposition
81.05.Lg Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
79.60.Fr Polymers; organic compounds

Study of C4F8/CO and C4F8/Ar/CO plasmas for highly selective etching of organosilicate glass over Si3N4 and SiC

Li Ling, X. Hua, X. Li, G. S. Oehrlein, F. G. Celii, K. H. R. Kirmse, P. Jiang, Yicheng Wang, and H. M. Anderson

J. Vac. Sci. Technol. A 22, 236 (2004); http://dx.doi.org/10.1116/1.1638780 (9 pages) | Cited 3 times

Online Publication Date: 14 January 2004

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We have examined the effect of CO addition to C4F8 or C4F8/Ar plasmas for selective etching of organosilicate glass (OSG) over SiC etch stop layers. The variation of important gas phase species, thin film etching rates and surface chemistry with feedgas composition was determined. CO addition exhibits dramatically different consequences on OSG/SiC etching selectivity when added to C4F8 or C4F8/Ar plasmas containing a high proportion of Ar. An improvement of the OSG/SiC etching selectivity results from CO addition to C4F8. We observe little CO dissociation in this case, which is plausible considering the lower dissociation energy threshold of C4F8 relative to CO. X-ray photoelectron spectroscopy (XPS) analysis of OSG and SiC surfaces shows that the etching selectivity improvement for C4F8/CO may be explained not only by an increase of the thickness and a reduction of the F/C ratio of the steady-state fluorocarbon surface layer on the SiC surface during etching, but little incorporation of CO into deposited fluorocarbon films. Adding CO to C4F8/Ar discharges with a high proportion of Ar leads to a reduction of the OSG/SiC etching selectivity. Significant dissociation of CO in Ar-rich C4F8/Ar/CO discharges is observed, consistent with the fact that the dissociation energy threshold of CO is lower than the Ar ionization and metastable energies. Oxygen incorporation in deposited fluorocarbon films and a reduction of the steady-state fluorocarbon surface layer thickness on SiC are observed by XPS in this case, explaining the loss of OSG/SiC etching selectivity for C4F8/Ar/CO discharges. © 2004 American Vacuum Society.
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52.77.Bn Etching and cleaning
81.65.Cf Surface cleaning, etching, patterning
82.30.Nr Association, addition, insertion, cluster formation
81.05.Kf Glasses (including metallic glasses)

Control of nitrogen depth profile in ultrathin oxynitride films formed by pulse-time-modulated nitrogen beams

Seiji Samukawa, Youichi Minemura, and Seiichi Fukuda

J. Vac. Sci. Technol. A 22, 245 (2004); http://dx.doi.org/10.1116/1.1641047 (5 pages) | Cited 12 times

Online Publication Date: 14 January 2004

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Ultrathin Si oxynitride (SiOxNy) films have been identified as leading candidates to replace conventional SiO2 gate dielectrics in current and future ultralarge-scale integrated circuits. Remote plasma processes to nitridate the top surface of thermally grown oxides have been developed and employed in complementary metal–oxide–silicon device applications. However, it is very difficult to control the nitrogen depth profile in ultrathin Si oxynitride film using plasma processing and there are many serious problems, such as plasma radiation damage and increases in interface state density due to the N penetrating into the SiO2–Si interface. To overcome these problems, we propose the use of pulse-time-modulated N2 neutral beams. We first found that the nitrogen depth profile in ultrathin Si oxynitride film could be controlled by changing the pulse-on time and source power in the pulse-time-modulated N2 neutral beams. We speculated that injected N2 was diffused due to the surface activation with the energetic neutral beam at a time constant of a few tens of microseconds in the thermal SiO2 film. Additionally, by increasing the substrate temperature to 300 °C, SiO–N bonds were effectively formed and a shallower, sharper, and higher density N concentration profile in a thin 2 nm SiO2 film was produced using a pulsed N2 neutral beam. © 2004 American Vacuum Society.
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61.72.S- Impurities in crystals
52.50.Gj Plasma heating by particle beams
52.77.Dq Plasma-based ion implantation and deposition
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation

Preparation of TiN films by arc ion plating using dc and pulsed biases

M. D. Huang, Y. P. Lee, C. Dong, G. Q. Lin, C. Sun, and L. S. Wen

J. Vac. Sci. Technol. A 22, 250 (2004); http://dx.doi.org/10.1116/1.1641050 (5 pages) | Cited 6 times

Online Publication Date: 14 January 2004

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TiN hard coatings were prepared by arc ion plating with both direct current (dc) and pulsed biases. An extensive investigation was undertaken to determine the effects of the substrate temperature on the mechanical properties and the microstructures of films. The results show that the substrate temperature is decreased evidently when a pulsed bias instead of a dc one is employed. At the same time, the microstructures and the properties are also improved. A low-temperature arc ion plating can be realized by using pulsed biases. © 2004 American Vacuum Society.
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81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.55.A- Nucleation and growth
68.60.Bs Mechanical and acoustical properties
68.35.Gy Mechanical properties; surface strains
81.40.Np Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure

Some considerations on heater design for simultaneous deposition of large-area double-sided high-Tc superconducting thin films

J. J. Chen, B. W. Tao, X. Z. Liu, and Y. R. Li

J. Vac. Sci. Technol. A 22, 255 (2004); http://dx.doi.org/10.1116/1.1641051 (5 pages)

Online Publication Date: 14 January 2004

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Some important factors on heater design, which is used for the deposition of high-Tc superconducting thin films, have been discussed in this article. Compared to radiation heat transfer directly from the heater to the substrate, the conduction and convection due to the inlet gas (oxygen or/and argon) are negligible. A theoretical model based on radiation heat transfer has been proposed by which some heater configurations have been discussed in detail. The temperature distribution in a simultaneous deposition system with two sputtering sources is improved by either proper off-axis displacement accompanied with in-plane substrate rotation or increasing the distance of the two heating sheets. For a biaxial rotating substrate, a cylindrical heater is proposed. The temperature distribution in the heater can be modulated by varying the input power ratio of the two heating parts. And, the total radiation power imposed on the substrate in every out-of-plane revolution is excellently homogeneous. © 2004 American Vacuum Society.
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74.78.-w Superconducting films and low-dimensional structures
85.40.Sz Deposition technology
44.10.+i Heat conduction

Plasma characteristics in pulsed direct current reactive magnetron sputtering of aluminum nitride thin films

Jung W. Lee, Jerome J. Cuomo, and Mohamed Bourham

J. Vac. Sci. Technol. A 22, 260 (2004); http://dx.doi.org/10.1116/1.1641049 (4 pages) | Cited 9 times

Online Publication Date: 22 January 2004

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Plasma diagnostics is important to identify plasma parameters and generate reproducible plasma in magnetron sputtering. Langmuir probes have been used to measure local plasma parameters such as electron temperature (Te), charge densities (ne and ni), and plasma potential (Vp). Pulsed direct current (dc) power in the midfrequency range (50–250 kHz) has been used in growing insulating films without charging accumulations at target. Recent investigations showed increased energetic particle bombardment of the substrate in pulsed power. In this work, aluminum nitride thin films were fabricated by pulsed dc power sputter deposition. The argon and nitrogen plasma was characterized by Langmuir probe measurement. The electron temperature in argon and nitrogen plasma was observed to increased from 3.06 to 5.32 eV when the pulsed dc frequency increased from 75 to 250 kHz. The ion density and energy flux were found to increase with frequency. This is believed to be from the stochastic heating generated by the fast oscillation in the target voltage wave form. The measured plasma characteristics were correlated with the crystal orientation of AlN thin films. The crystal structure of AlN thin films changed to (002) preferred orientations as the ion and energy flux increased. © 2004 American Vacuum Society.
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81.15.Cd Deposition by sputtering
68.55.A- Nucleation and growth
52.70.Ds Electric and magnetic measurements
52.25.-b Plasma properties

Reactive physical vapor deposition of TixAlyN: Integrated plasma-surface modeling characterization

Da Zhang and J. K. Schaeffer

J. Vac. Sci. Technol. A 22, 264 (2004); http://dx.doi.org/10.1116/1.1641048 (8 pages) | Cited 1 time

Online Publication Date: 29 January 2004

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Reactive physical vapor deposition (RPVD) has been widely applied in the microelectronic industry for producing thin films. Fundamental understanding of RPVD mechanisms is needed for successful process development due to the high sensitivity of film properties on process conditions. An integrated plasma equipment-target nitridation modeling infrastructure for RPVD has therefore been developed to provide mechanistic insights and assist optimal process design. The target nitridation model computes target nitride coverage based on self-consistently derived plasma characteristics from the plasma equipment model; target sputter yields needed in the plasma equipment model are also self-consistently derived taking into account the yield-suppressing effect from nitridation. The integrated modeling infrastructure has been applied to investigating RPVD processing with a Ti0.8Al0.2 compound target and an Ar/N2 gas supply. It has been found that the process produces athermal metal neutrals as the primary deposition precursor. The metal stoichiometry in the deposited film is close to the target composition due to the predominance of athermal species in the flux that reaches the substrate. Correlations between process parameters (N2 flow, target power), plasma characteristics, surface conditions, and deposition kinetics have been studied with the model. The deposition process is characterized by two regimes when the N2 flow rate is varied. When N2 is dilute relative to argon, target nitride coverage increases rapidly with increasing N2 flow. The sputter yield and deposition rate consequently decrease. For less dilute N2 mixtures, the sputter yield and deposition rate are stable due to the saturation of target nitridation. With increasing target power, the electron density increases nearly linearly while the variation of N generation is much smaller. Target nitridation and its suppression of the sputter yield saturate at high N2 flow rendering these parameters insensitive to target power variation. The deposition rate, however, increases with target power as a result of the increased ion energy and flux at the target. © 2004 American Vacuum Society.
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52.77.Dq Plasma-based ion implantation and deposition
81.65.Lp Surface hardening: nitridation, carburization, carbonitridation
81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.A- Nucleation and growth

Zirconia-alumina nanolaminate for perforated pitting corrosion protection of stainless steel

W. F. Gaertner, E. E. Hoppe, M. A. Omari, R. S. Sorbello, and C. R. Aita

J. Vac. Sci. Technol. A 22, 272 (2004); http://dx.doi.org/10.1116/1.1642650 (9 pages) | Cited 5 times

Online Publication Date: 29 January 2004

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The subject of this article is control of perforated pit growth in 316L stainless steel by application of an artificial overlayer film. The protection afforded by 250 nm thick films with two ZrO2–Al2O3 nanolaminate architectures, single-layer ZrO2, and single-layer Al2O3 under cyclic polarization in saline electrolyte is reported here. The post-exposure morphology is characterized by scanning electron microscopy with in situ electron energy dispersive spectroscopy. The films’ diverse behavior is analyzed in terms of a model for perforated pit growth that requires partial pit occlusion until an autocatalytic geometry is established. The results show that the key property a film must have to arrest the development of autocatalytic geometry is the capability to fracture locally so that the electrolyte from the pit freely mixes with the bulk electrolyte and the pit interior becomes passivated. We show how a nanolaminate with 5.0 nm tetragonal ZrO2–5.0 nm amorphous Al2O3 bilayers sustains local fracture (blow holes) without widespread cracking and is protective against perforated pit growth. © 2004 American Vacuum Society.
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81.65.Kn Corrosion protection
61.46.-w Structure of nanoscale materials
81.65.Rv Passivation
68.35.B- Structure of clean surfaces (and surface reconstruction)

Phase transformation of tungsten films deposited by diode and inductively coupled plasma magnetron sputtering

G. S. Chen, H. S. Tian, C. K. Lin, Gin-Shiang Chen, and H. Y. Lee

J. Vac. Sci. Technol. A 22, 281 (2004); http://dx.doi.org/10.1116/1.1642651 (6 pages) | Cited 3 times

Online Publication Date: 29 January 2004

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In this work we employ conventional (diode) and inductively coupled plasma (ICP) magnetron sputtering to deposit tungsten thin films of thickness 40 nm. The effect of varying the deposition parameters (background pressure, substrate bias and, particularly, the argon sputtering pressure) on transformation of the films’ phases and related physical properties was investigated using grazing incidence x-ray diffraction, scanning electron microscopy, and transmission electron microscopy, as well as electrical resistivity evaluation and bending-beam stress measurements. Tungsten films deposited by diode sputtering at any argon sputtering pressure from 5×10−1 Pa (5×10−3 mb) up to 2.0 Pa over a broad parameter window are dominated by β–W, thus yielding resistivity that could reach ∼190 μΩ cm. Conversely, over a broad range of sputtering pressures and substrate biases, the ICP sputtering is capable of depositing α-W thin films that exhibit markedly reduced resistivity of only ∼20 μΩ cm. The impact of varying the deposition parameters on the residual stress, phase distribution, microstructure, and crystallinity of the deposited films is discussed in terms of an energy-enhanced deposition mechanism and the well-known zone-structure model proposed earlier. © 2004 American Vacuum Society.
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68.55.-a Thin film structure and morphology
68.55.Nq Composition and phase identification
68.60.-p Physical properties of thin films, nonelectronic
81.30.-t Phase diagrams and microstructures developed by solidification and solid-solid phase transformations
81.15.Cd Deposition by sputtering
52.77.Dq Plasma-based ion implantation and deposition
68.35.Rh Phase transitions and critical phenomena

Characterization of graded InGaN/GaN epilayers grown on sapphire

T. L. Song, S. J. Chua, E. A. Fitzgerald, P. Chen, and S. Tripathy

J. Vac. Sci. Technol. A 22, 287 (2004); http://dx.doi.org/10.1116/1.1644114 (6 pages) | Cited 5 times

Online Publication Date: 29 January 2004

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Atomic force microscopy, scanning electron microscopy, micro-Raman, and photoluminescence techniques have been used to characterize graded InGaN/GaN epilayers grown on sapphire. These graded InGaN/GaN can be employed as buffers that can relax the strain arising from the lattice and thermal mismatch in nitride epilayers grown on sapphire. Compared to the conventional two-step high temperature bulk GaN, an enhanced strain relaxation was observed in the GaN grown on a gradually graded InGaN buffer with an intermediate thin GaN layer. The function of the intermediate layer was to progressively relax the strain that built up in the InGaN layer after a certain thickness. The optimum growth conditions of the intermediate layer play a major role in promoting the suppression and filling of the V-pits in the GaN cap layer, and were empirically found to be a thin 10 nm GaN grown at 750 °C and annealed at 1000 °C. Based on the statistical distribution of the size of the V-pits opening, the formation of V-pits was also investigated. © 2004 American Vacuum Society.
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68.55.-a Thin film structure and morphology
78.66.Fd III-V semiconductors
68.35.B- Structure of clean surfaces (and surface reconstruction)
68.37.Ps Atomic force microscopy (AFM)
78.30.Fs III-V and II-VI semiconductors

Effects of voltage distribution along an induction coil and discharge frequency in inductively coupled plasmas

Manabu Edamura and Eric C. Benck

J. Vac. Sci. Technol. A 22, 293 (2004); http://dx.doi.org/10.1116/1.1641052 (9 pages) | Cited 6 times

Online Publication Date: 9 February 2004

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Recent etching processes often use low to middle plasma density in order to increase etching controllability or to reduce charging damages. In inductively coupled plasmas (ICPs) in low to middle plasma density, effects of a capacitively coupled discharge (E discharge) on the total plasma characteristic cannot be neglected. It is thus more difficult to understand the ICPs in low to middle density than to understand high-density ICPs which can be regarded as being generated by an inductively coupled discharge (H discharge) only. In this research, we changed the voltage distribution of the induction coil of an ICP-modified gaseous electronics conference reference cell by inserting a termination capacitor between the coil and the ground. We also changed the discharge frequencies (6.28 MHz, 13.56 MHz, and 20 MHz), and investigated their effects on Ar plasmas. As a result, it was observed that the structure of the E discharge was changed by the voltage distribution of the coil and, therefore, E-to-H mode transitions were dramatically altered. Although no difference between the electron energy distribution functions (EEDFs) was observed in a pure H discharge with an electrostatic shield for the experimental conditions studied (1.33 Pa and 150 W), it was observed that EEDFs were affected by the discharge frequency without an electrostatic shield, probably due to a decrease of electron density by the effect of an E discharge and an increase of the ratio of the E to H discharge with increasing discharge frequency. © 2004 American Vacuum Society.
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52.25.-b Plasma properties
52.35.Qz Microinstabilities (ion-acoustic, two-stream, loss-cone, beam-plasma, drift, ion- or electron-cyclotron, etc.)
52.77.Bn Etching and cleaning
52.50.Dg Plasma sources
52.80.Pi High-frequency and RF discharges

Electron cyclotron resonance plasma enhanced metalorganic chemical vapor deposition system with monitoring in situ for epitaxial growth of group-III nitrides

Yin Xu, Biao Gu, and Fu-Wen Qin

J. Vac. Sci. Technol. A 22, 302 (2004); http://dx.doi.org/10.1116/1.1641055 (7 pages) | Cited 6 times

Online Publication Date: 9 February 2004

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An electron cyclotron resonance (ECR) plasma enhanced metalorganic chemical vapor deposition (PEMOCVD) system equipped with reflection high-energy electron diffraction (RHEED) has been developed and utilized for epitaxial growth of GaN and AlN on sapphire substrates by PEMOCVD. Since the multicusp cavity-coupling ECR plasma source was adopted to provide active precursors, the growth temperatures were decreased to 600–700 °C and the working pressures were decreased down to the region <1 Pa also, which make RHEED monitoring in situ possible for the growth surface. The nitrogen plasma densities Ne∼1.0–3.0×1010 cm−3 with a uniformity <±5% over a 10 cm diameter area, the electron temperatures kTe∼2–3 eV, the ion temperatures kTi⩽1 eV, and the plasma potentials Vs<18 V near the substrate holder for the typical film growth conditions: The pressure Po∼3×10−1–8×10−1 Pa and the microwave power Pw∼400–750 W. The experiment results demonstrated important roles of the plasma for sapphire substrate pretreatment, initial nucleation, and epitaxy growth of a large lattice mismatch heterojunction, GaN/(0001) Al2O3 at low temperature. The chemistry and mechanism of hydrogen (H)-plasma cleaning and nitrogen (N)-plasma nitriding, and the 30° rotation of a (0001) nitride plane produced by the nitriding with respect to the (0001) Al2O3 to reduce the lattice constant mismatch are discussed. The epilayers of GaN and AlN with better quality and relatively smooth surface were obtained. The full width of half maximum (FWHM) of a GaN (0002) diffraction peak of x-ray diffraction from a 0.3 μm thick GaN film was 15 arc min and the FWHM of AlN (0002) diffraction peak from a 0.3 μm thick AlN film was 12 arc min. Film surface morphology was observed by atomic force microscopy. © 2004 American Vacuum Society.
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81.15.Gh Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
52.77.Dq Plasma-based ion implantation and deposition

Miniaturized vacuum gauges

St. Wilfert and Chr. Edelmann

J. Vac. Sci. Technol. A 22, 309 (2004); http://dx.doi.org/10.1116/1.1642649 (12 pages) | Cited 10 times

Online Publication Date: 9 February 2004

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Due to the rapid advancement in microsystem and micromachining technology in the past several years, the most important common pressure measuring principles have been successfully applied in miniaturized vacuum sensors. In addition to MicroPiranis®, microstructured gas friction gauges and miniaturized capacitance manometers have been developed recently too, whose dimensions are already in the millimeter and partly in the micrometer range. Exceptions in this development are ionization gauges which, due to their basic measuring principle, cannot be arbitrarily miniaturized without substantial restrictions in their operating performance. The article gives a rough summary of the present level of development of selected types of miniaturized vacuum gauges and points out limits and causes for the restricted miniaturizability of certain total pressure vacuum gauges. © 2004 American Vacuum Society.
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07.30.Dz Vacuum gauges
85.85.+j Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.07.Df Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
01.30.Rr Surveys and tutorial papers; resource letters

Effect of concurrent N2+ and N+ ion bombardment on the plasma-assisted deposition of carbon nitride thin film

Z. X. Cao and H. Oechsner

J. Vac. Sci. Technol. A 22, 321 (2004); http://dx.doi.org/10.1116/1.1644112 (3 pages) | Cited 2 times

Online Publication Date: 9 February 2004

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Nitrogen ion beam extracted from low-temperature plasmas consists of both atomic and molecular ions, and often the latter is dominant. In preparing nitrides thin films with low-energy nitrogen ions striking the growing surface, the atomic and molecular ions operate at different energy scales. While the atomic ions already provoke the subplantation growth at about 120 eV, the molecular ions that first dissociate at the surface may need roughly a doubled energy. Therefore, the energy dependence of various film characters displays a rather nontrivial behavior. We illustrate this effect with the electron-cyclotron-wave resonance plasma assisted deposition of amorphous CN film, for which the variation of the film composition, microhardness, and surface roughness with the ion energy was investigated. © 2004 American Vacuum Society.
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81.15.Jj Ion and electron beam-assisted deposition; ion plating
68.55.-a Thin film structure and morphology

Growth and characterization of cubic CdS epilayers on GaAs substrates

Young-Moon Yu, Ki-Seon Lee, Byungsung O, Pyeong Yeol Yu, Chang-Soo Kim, Yong Dae Choi, and Hee-Joong Yun

J. Vac. Sci. Technol. A 22, 324 (2004); http://dx.doi.org/10.1116/1.1647597 (4 pages) | Cited 8 times

Online Publication Date: 9 February 2004

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Cubic CdS epilayers were grown on (100) GaAs substrate by hot-wall epitaxy. X-ray diffraction and photoluminescence measurements revealed that the hexagonal phase was dominant in the layers grown at low temperatures, and the cubic phase became dominant with increasing growth temperature. The photoluminescence emission lines in cubic CdS were identified. © 2004 American Vacuum Society.
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81.05.Ea III-V semiconductors
78.55.Cr III-V semiconductors

Easy method enhancing the sensitivity of a helium mass-spectrometer leak detector

G. Firpo and A. Pozzo

J. Vac. Sci. Technol. A 22, 328 (2004); http://dx.doi.org/10.1116/1.1647592 (4 pages) | Cited 2 times

Online Publication Date: 12 February 2004

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Commercial He mass spectrometer leak detectors usually do not provide sufficient sensitivity to perform accurate measurements of the permeation rate of He through glass. Ultrasensitive dedicated systems have adeguate sensitivity but involve high costs and complex procedures. However, both cryogenics and photomultiplier technology routinely demand this goal. Here, we propose a novel method to increase the sensitivity of commercial devices to easily measure accurate permeation rate. We modified a commercial leak detector by reducing the pumping speed at the inlet of the rotary pump, thus increasing its sensitivity by one order of magnitude. The modified detector was used to measure the leak rate of the permeation of He through the glass walls of a photomultiplier. Further improvements made to decrease the minimum detectable signal were limited by the high ultimate pressure in the spectrometer tube. © 2004 American Vacuum Society.
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07.30.Hd Vacuum testing methods; leak detectors
07.75.+h Mass spectrometers

Preferred orientation and film structure of TaN films deposited by reactive magnetron sputtering

Suguru Noda, Kun Tepsanongsuk, Yoshiko Tsuji, Yuya Kajikawa, Yoshifumi Ogawa, and Hiroshi Komiyama

J. Vac. Sci. Technol. A 22, 332 (2004); http://dx.doi.org/10.1116/1.1647593 (7 pages) | Cited 4 times

Online Publication Date: 12 February 2004

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The structural evolution of tantalum nitride (TaN) films deposited by reactive rf magnetron sputtering were investigated in detail by using transmission electron microscopy (TEM) and x-ray diffractometry (XRD) for a wide range of thickness from 2 nm to 2 μm under various N2/Ar flow ratios from 0 to 20 vol % on both amorphous SiO2 (a-SiO2) and randomly oriented polycrystalline fcc TaN (poly-fcc-TaN) substrates. Although the films had various crystalline structures [including tetragonal Ta, bcc Ta(N), and fcc TaN] of different preferred orientation (PO) and had amorphous phases depending on deposition conditions, the formation mechanism of these structures was systematically explained by mapping them on 2D graphs of film thickness vs N2/Ar flow ratio. The texture map of films deposited on a-SiO2 substrates reflected both nucleation and growth stages, whereas that of films deposited on poly-fcc-TaN substrates reflected mainly the growth stage. Comparison of these two maps allowed the nucleation and growth processes to be separately discussed. For films deposited at 4 vol % N2/Ar ratio on a-SiO2 substrates, an amorphous phase initially appeared when the film thickness was 1.8–3.5 nm. When the film thickness was about 7 nm, nucleation occurred to form fcc TaN without any PO. When the thickness was about 100 nm, (111) PO appeared. Finally, when the thickness exceeded 200 nm, (200) PO dominated the film. Cross-sectional TEM micrographs revealed that evolutionary selection growth occurred when the film was 200-nm-thick to cause the PO change. (111) PO was preferred at relatively low (2–3 vol %) and high (⩾10 vol %) N2/Ar ratios, whereas (200) was preferred at medium N2/Ar ratio (4–7 vol %). © 2004 American Vacuum Society.
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81.15.Cd Deposition by sputtering
68.47.De Metallic surfaces
85.40.Ls Metallization, contacts, interconnects; device isolation
68.55.-a Thin film structure and morphology
66.30.Qa Electromigration

High temperature processing of TiO2 thin films for application in silicon solar cells

Bryce S. Richards, S. Raymond Richards, Matthew B. Boreland, and David N. Jamieson

J. Vac. Sci. Technol. A 22, 339 (2004); http://dx.doi.org/10.1116/1.1647594 (10 pages) | Cited 7 times

Online Publication Date: 12 February 2004

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Low temperature deposited coatings have the potential to reduce the production costs of silicon (Si) photovoltaic devices, such as the buried-contact (BC) solar cell. This work investigates the potential of titanium dioxide (TiO2) films to replace silicon dioxide (SiO2) or nitride coatings currently implemented in the BC fabrication sequence, which requires films to be stable at temperatures up to 1000 °C in a variety of gas atmospheres. The authors demonstrate that: (i) TiO2 films do not reduce the bulk minority carrier lifetime of the silicon wafer after lengthy high temperature processing, however chemical reduction of the TiO2 film can occur if samples are not loaded in an oxygen-containing ambient; (ii) a thin SiO2 passivation layer can be formed at the TiO2:Si interface by performing a brief oxidation after TiO2 film deposition; (iii) while TiO2 coatings function as a phosphorus diffusion barrier, reactions between TiO2 and the phosphorus source result in irreversible damage to the TiO2 film; (iv) phosphorus-doped TiO2 films can act as an n-type dopant source, however further reactions with phosphorus limit the usefulness of the film. Thus, TiO2 films are compatible with the high temperature processing required for BC solar cells, but not with any phosphorus diffusion steps. © 2004 American Vacuum Society.
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77.55.-g Dielectric thin films
84.60.Jt Photoelectric conversion
72.20.Jv Charge carriers: generation, recombination, lifetime, and trapping
81.65.Mq Oxidation
81.65.Rv Passivation

Effect of deposition parameters on properties of ITO films prepared by reactive middle frequency pulsed dual magnetron sputtering

A. I. Rogozin, M. V. Vinnichenko, A. Kolitsch, and W. Möller

J. Vac. Sci. Technol. A 22, 349 (2004); http://dx.doi.org/10.1116/1.1647595 (7 pages) | Cited 14 times

Online Publication Date: 12 February 2004

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ITO layers with low resistivity and high visible transmittance were produced by means of middle frequency reactive dual magnetron sputtering. The influence of base pressure, Ar/O2 ratio and magnetron pulse duration on the film composition, structure, electrical, and optical properties has been investigated. The deposition rate is proportional to the magnetron operation power at changing pulse duration and constant Ar and O2 flows. At enhanced O2 flows an onset of the magnetron target oxidation is discussed as a reason for the decrease of the deposition rate. The presence of water vapor in the residual gas is determined to be a reason for deterioration of resistivity and optical transmittance observed for ITO films produced at a base pressures higher than 5⋅10−4 Pa. It is demonstrated that spectroscopic ellipsometry can be used as a noncontact tool to monitor the resistivity of ITO films. © 2004 American Vacuum Society.
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68.55.-a Thin film structure and morphology
73.61.Le Other inorganic semiconductors
78.66.Li Other semiconductors
81.05.Hd Other semiconductors
81.15.Cd Deposition by sputtering
78.40.Ha Other nonmetallic inorganics
81.65.Mq Oxidation

Effects of mesh-assisted carbon plasma immersion ion implantation on the surface properties of insulating silicon carbide ceramics

Ricky K. Y. Fu, Ka Leung Fu, Xiubo Tian, and Paul K. Chu

J. Vac. Sci. Technol. A 22, 356 (2004); http://dx.doi.org/10.1116/1.1648676 (5 pages) | Cited 5 times

Online Publication Date: 12 February 2004

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Plasma immersion ion implantation (PIII) is an effective materials modification and synthesis technique but has seldom been applied to ceramic materials due to the high electrical resistance that reduces the ion bombardment energy and sometimes causes serious electrical arcing in the instrument. Even in cases where PIII is applicable, the surface properties of the implanted insulating materials can be seriously affected due to the low ion energy and materials damage from electrical arcing. In order to enhance the surface and mechanical properties such as wear resistance of ceramic materials used in many industrial applications, surface modification is needed. In this work, we conduct carbon implantation into sintered α-SiC (silicon carbides that are widely used in vacuum ceramic bearings) using mesh-assisted plasma immersion ion implantation to enhance the surface properties. The use of a conducting grid is necessitated by the high electrical resistance that induces a large voltage drop across the substrate when a negative voltage is applied to the back of the specimen. The rough surfaces make direct assessment of the shallow depth profiles difficult and so we directly measure the hardness and surface friction coefficients, both of which are significantly enhanced after implantation. Our data suggest different wear mechanisms for the unimplanted and implanted samples as inferred from the surface topography and wear tracks. © 2004 American Vacuum Society.
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68.35.Gy Mechanical properties; surface strains
62.20.Qp Friction, tribology, and hardness
81.40.Pq Friction, lubrication, and wear
52.77.Dq Plasma-based ion implantation and deposition

Thickness dependence of the properties of highly c-axis textured AlN thin films

F. Martin, P. Muralt, M.-A. Dubois, and A. Pezous

J. Vac. Sci. Technol. A 22, 361 (2004); http://dx.doi.org/10.1116/1.1649343 (5 pages) | Cited 54 times

Online Publication Date: 12 February 2004

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The influence of film thickness on the material properties of aluminum nitride (AlN) thin films deposited on Pt(111) electrodes has been investigated experimentally by means of x-ray diffraction, dielectric response, atomic force microscopy, interferometry measurement of effective d33, and residual stress measurement. The thickness was varied between 35 nm and 2 μm. Full width at mid-height of the rocking curve decreased from 2.60 to 1.14°, rms roughness increased from 3.8 to 18.6 Å, the effective d33, namely d33,f, from 2.75 to 5.15 pm/V. The permittivity ϵAlN was stable at 10.2, whereas the dielectric losses decreased from 1% to 0.1%. The breakdown electric field under dc voltages varied between 4.0 and 5.5 MV/cm. © 2004 American Vacuum Society.
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68.55.-a Thin film structure and morphology
68.60.Bs Mechanical and acoustical properties
77.22.Ch Permittivity (dielectric function)
61.05.cm X-ray reflectometry (surfaces, interfaces, films)

Effect of ion beam energy on magnetic properties of CoCrPt and CoPt thin films

Jinqiu Zhang, Haifeng Wang, Michael Alex, and Lena Miloslavsky

J. Vac. Sci. Technol. A 22, 366 (2004); http://dx.doi.org/10.1116/1.1649987 (5 pages)

Online Publication Date: 12 February 2004

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The magnetic properties of Cr/CoPt and Cr/CoCrPt thin films prepared by ion beam deposition with Xe ions (0.6–1.5 kV) have been investigated. The effect of ion beam energy on the structural and magnetic properties has been studied. A strong dependence of in-plane coercivity on the beam energy was observed and the coercivity increased with beam energy for both CoPt and CoCrPt thin films. With increasing beam energy from 600 to 1500 eV, the coercivity for CoPt thin films increased from 1700 to 2100 Oe. In addition, CoPt thin films have a greater advantage over CoCrPt thin films. A 40% increase in coercivity for CoPt thin films was obtained at the same remanent magnetization-thickness (Mrt) product as compared to CoCrPt. A minimum thickness of 20 Å for the Cr underlayer and 600 eV beam energy were required for constant coercivity and Mrt. X-ray diffraction studies indicated that CoPt(10math0) texture and in-plane hcp c-axis orientation were enhanced with increased beam energy. The increase of coercivity with beam energy is attributed to an increase in the peak intensity ratio (10math0)/(0002). The decrease of grain size for CoPt(10math0) texture with beam energy was attributed to contribute to improvement in coercivity. Compositional analysis using inductively coupled plasma indicated that the Pt content in CoPt thin films increased with beam energy. The increase of Pt content in the thin films accompanied by an increase in the d spacing (lattice constant) improved in-plane coercivity. From magnetic force microscopy studies, lower inter-granular exchange coupling was observed at higher beam energy. © 2004 American Vacuum Society.
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75.70.Ak Magnetic properties of monolayers and thin films
75.50.Ww Permanent magnets
81.15.Jj Ion and electron beam-assisted deposition; ion plating

Electron beam fluorescence temperature measurements of N2 in a semiconductor plasma reactor

M. Shimada, R. Cattolica, and G. R. Tynan

J. Vac. Sci. Technol. A 22, 371 (2004); http://dx.doi.org/10.1116/1.1644113 (6 pages) | Cited 6 times

Online Publication Date: 17 February 2004

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The rotational temperature of nitrogen molecules in inductively coupled plasma (ICP) discharge has been measured using the electron beam fluorescence (EBF) technique. The neutral gas temperature is an important parameter in understanding the energy balance and neutral radical uniformity in plasma processing. The EBF technique has been used to study rarefied flows, but has not been applied previously to characterize a semiconductor plasma reactor. In this work an electron beam was integrated into an inductively coupled semiconductor plasma reactor, and was used to excite neutral nitrogen molecules from the N2X 1Σg+ state into the excited molecular ion N2+B 2Σu+ state. The electron beam excitation process maps the rotational population distribution of the original ground state into the excited molecular ion state following a dipole model with ΔK=±1. The rotational temperature, which is thought to be equivalent to the neutral gas translational temperature under plasma reactor conditions, can be determined from the rotational intensity distribution of the fluorescence spectrum from the N2+B 2Σu+ state. For the range of neutral gas temperatures found in the plasma reactor a dipole model of the excitation-emission process provides good agreement with the measured spectrum. A least-square fitting procedure comparing the model and measured emission spectra is used to determine the rotation temperature. In this article the first EBF measurements of gas heating in an ICP reactor at different gas pressures (20, 50 mTorr) and plasma source input powers (250, 500, and 1000 W) are reported. © 2004 American Vacuum Society.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.80.Dy Low-field and Townsend discharges

Optical emission diagnostic of a pulsed arc discharge

E. Restrepo and A. Devia

J. Vac. Sci. Technol. A 22, 377 (2004); http://dx.doi.org/10.1116/1.1647598 (6 pages) | Cited 14 times

Online Publication Date: 17 February 2004

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A spectroscopic analysis of plasma properties produced in a new type of pulsed-vacuum arc system, is presented herein. The system is used to produce TiN coatings and the process is carried out by using a vacuum chamber filled with nitrogen. Inside the chamber there are two opposite electrodes (the anode being the sample and the cathode acting as the target). A bank of capacitors is charged up to 300 V. Thereafter, it is discharged between the electrodes by means of a RLC circuit producing the plasma. Some species (Ti, Ti I, N, N I, N2, N2 I, and TiN) have been identified in the plasma. Electron and excitation temperatures were calculated by means of titanium atomic lines assuming local thermodynamic equilibrium (LTE), but supposing that Texc is different to Te, using the Boltzmann plot and line-continuum ratio, obtaining approximate values of 1 eV. Electron density in the order of 1013 cm−3 was calculated using stark broadening of atomic nitrogen lines at 414.6 and 492.8 nm. Moreover, the plasma behavior as a function of the pressure was studied in this article. © 2004 American Vacuum Society.
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52.70.Kz Optical (ultraviolet, visible, infrared) measurements
52.25.-b Plasma properties
52.80.Mg Arcs; sparks; lightning; atmospheric electricity
52.80.Vp Discharge in vacuum
52.50.-b Plasma production and heating
68.55.-a Thin film structure and morphology
85.40.Ls Metallization, contacts, interconnects; device isolation

Analytical modeling of rarefied Poiseuille flow in microchannels

Sun Yuhong and W. K. Chan

J. Vac. Sci. Technol. A 22, 383 (2004); http://dx.doi.org/10.1116/1.1647599 (12 pages) | Cited 3 times

Online Publication Date: 17 February 2004

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The prediction of rarefied gas flow in the transition regime remains an obstacle due to its complexity. The moment method is commonly used in kinetic theory of gases to obtain approximate solutions in this regime, though substantial effort is still needed either numerically or mathematically. In this article Grad’s 13-moment method was first applied to the derivation of a new governing equation for Poiseuille flow in microchannels and novel boundary conditions were introduced. For validation purposes, Poiseuille flow in micro channels was investigated. The flow rate and velocity profiles were obtained analytically. The results were compared with the linearized Boltzmann equation and available experimental data. The error is within 10% in both slip and transition regimes. This shows a substantial improvement over first-, and second-order slip models where the errors can be as high as several tens or even hundreds of percent. The major attraction of the current approach is that it allows a simple analytical equation to explain the effects of various forces on the velocity profiles, flow rates, and pressure distributions. © 2004 American Vacuum Society.
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47.60.-i Flow phenomena in quasi-one-dimensional systems
47.45.Gx Slip flows and accommodation
51.10.+y Kinetic and transport theory of gases

Growth and characterization of hafnium silicate films prepared by UV/ozone oxidation

Prakaipetch Punchaipetch, Gaurang Pant, M. J. Kim, Robert M. Wallace, and Bruce E. Gnade

J. Vac. Sci. Technol. A 22, 395 (2004); http://dx.doi.org/10.1116/1.1649346 (6 pages) | Cited 1 time

Online Publication Date: 17 February 2004

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Physical and electrical properties of hafnium silicate (HfSixOy) dielectric films prepared by room-temperature UV/ozone (O3) oxidation of hafnium silicide (HfSi2) are reported. Angle-resolved x-ray photoelectron spectroscopy was used to determine chemical bonding at the film interface and within the bulk film. These films, with 12 at. % Hf composition, have a dielectric constant (κ) of ∼8–9 and exhibit a flat-band voltage shift of 60 mV. The leakage current density at VFB+1 V is 4.7×10−5 A/cm2 for a 4.7-nm-thick film (capacitance equivalent thickness=2.6 nm) and breakdown strength was >8 MV/cm. © 2004 American Vacuum Society.
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77.55.-g Dielectric thin films
79.60.Dp Adsorbed layers and thin films
77.22.Ch Permittivity (dielectric function)

Maximum entropy decomposition of quadrupole mass spectra

U. v. Toussaint, V. Dose, and A. Golan

J. Vac. Sci. Technol. A 22, 401 (2004); http://dx.doi.org/10.1116/1.1649345 (6 pages) | Cited 2 times

Online Publication Date: 17 February 2004

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We present an information-theoretic method called generalized maximum entropy (GME) for decomposing mass spectra of gas mixtures from noisy measurements. In this GME approach to the noisy, underdetermined inverse problem, the joint entropies of concentration, cracking, and noise probabilities are maximized subject to the measured data. This provides a robust estimation for the unknown cracking patterns and the concentrations of the contributing molecules. The method is applied to mass spectroscopic data of hydrocarbons, and the estimates are compared with those received from a Bayesian approach. We show that the GME method is efficient and is computationally fast. © 2004 American Vacuum Society.
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82.80.Ms Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.30.Lp Decomposition reactions (pyrolysis, dissociation, and fragmentation)

Nonselective and smooth etching of GaN/AlGaN heterostructures by Cl2/Ar/BCl3 inductively coupled plasmas

Yanjun Han, Song Xue, Tong Wu, Zhen Wu, Wenping Guo, Yi Luo, Zhibiao Hao, and Changzheng Sun

J. Vac. Sci. Technol. A 22, 407 (2004); http://dx.doi.org/10.1116/1.1641054 (6 pages) | Cited 4 times

Online Publication Date: 20 February 2004

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A systematic study of the nonselective and smooth etching of GaN/AlGaN heterostructures was performed using Cl2/Ar/BCl3 inductively coupled plasmas (ICPs). Nonselective etching can be realized by adjusting the BCl3 ratio in the Cl2/Ar/BCl3 mixture (20%–60%), increasing the ICP power, and decreasing the chamber pressure. Surface morphology of the etched heterostructures strongly depends on the gas chemistry and the chamber pressure, whereas selectivity and surface morphology show a slight dependence on the dc bias and total flow rate. Specifically, with the addition of 20% BCl3 to Cl2/Ar (4:1) gas mixture, nonselective etching of GaN/Al0.28Ga0.72N heterostructures at a high etch rate is maintained and the surface root-mean-square roughness is reduced from 10.6 nm to 0.5 nm, which is smoother than the as-grown sample. Auger electron spectroscopy analysis shows that the effective removal of residual oxygen from the surface of AlGaN during the etching process is crucial to the nonselective and smooth etching of GaN/AlGaN herterostructures at high etch rate. © 2004 American Vacuum Society.
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52.77.Bn Etching and cleaning
81.05.Ea III-V semiconductors
81.65.Cf Surface cleaning, etching, patterning
82.33.Xj Plasma reactions (including flowing afterglow and electric discharges)
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
82.20.Pm Rate constants, reaction cross sections, and activation energies

Chemical bonds of fluorocarbon films which can be a source of CFx radicals

N. Takada, T. Iida, K. Shibagaki, and K. Sasaki

J. Vac. Sci. Technol. A 22, 413 (2004); http://dx.doi.org/10.1116/1.1647596 (6 pages) | Cited 7 times

Online Publication Date: 20 February 2004

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Some experiments reported previously [e.g., K. Sasaki et al., J. Appl. Phys. 88, 5585 (2000)] show that fluorocarbon films can be a source of CFx radicals in fluorocarbon plasmas. In the present article, we examined the relationship between the degree of surface production and the chemical bonds of fluorocarbon films synthesized by various fluorocarbon plasmas with the addition of H2. The degree of surface production was evaluated from the absolute flux of CFx (x=1,2) radicals desorbed from fluorocarbon films. The composition of the chemical bonds was analyzed by x-ray photoelectron spectroscopy. As a result, significant surface production (>3×1015 cm−2 s−1) was observed when fluorocarbon film had the dominant –CF2 bond. The change in the dominant bond from –CF2 to –C–C resulted in the decrease in the degree of surface production. © 2004 American Vacuum Society.
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52.50.Dg Plasma sources
52.40.Hf Plasma-material interactions; boundary layer effects
61.50.Lt Crystal binding; cohesive energy
82.80.Pv Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

Fabrication of iron (III) oxide doped polystyrene shells

Pei-jun Cai, Yong-jian Tang, Lin Zhang, Kai Du, and Chang-gen Feng

J. Vac. Sci. Technol. A 22, 419 (2004); http://dx.doi.org/10.1116/1.1648675 (3 pages) | Cited 1 time

Online Publication Date: 20 February 2004

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A type of iron (III) oxide doped plastic shell used for inertial confinement fusion experiments has been fabricated by emulsion techniques. Three different phases of solution (W1, O, and W2) are used for the fabrication process. The W1 phase is a 1 wt % of sodium lauryl sulfate in water. This W1 phase solution is mixed with a 3 wt % Fe2O3–polystyrene (PS) solution in benzene-dichloroethane (O phase) while stirring. The resulting emulsion (W1/O) is poured into a 3 wt % aqueous polyvinyl alcohol solution (W2 phase) while stirring. The resulting emulsion (W1/O/W2) is then heated to evaporate benzene and dichloroethane, and thus a solid Fe2O3–PS shell is formed. The diameter and wall thickness of the shells range from 150 to 500 μm and 5 to 15 μm, respectively. The average surface roughness of the shells is 40 nm, similar to that of the usual PS shells. © 2004 American Vacuum Society.
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61.25.H- Macromolecular and polymers solutions; polymer melts
82.70.Kj Emulsions and suspensions

Fabrication of ferroelectric PbZrxTi1−xO3 thick films and their optical waveguide properties

G. J. Hu, S. H. Hu, X. J. Meng, G. S. Wang, Q. Zhao, J. L. Sun, J. H. Chu, N. Dai, L. Xu, L. Y. Liu, and D. X. Li

J. Vac. Sci. Technol. A 22, 422 (2004); http://dx.doi.org/10.1116/1.1648677 (3 pages) | Cited 1 time

Online Publication Date: 20 February 2004

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3 μm thick ferroelectric PbZrxTi1−xO3 films with x=0.4 and 0.5 have been fabricated on LaNiO3 coated silicon substrates by a modified sol-gel process. X-ray diffraction analysis shows that the films exhibit highly (100)-preferred orientation (α100>99%) and a single perovskite phase. Atomic force microscopy study shows that specimens possess smooth surfaces. The prism-film coupling measurement indicates that the system with the configuration of PbZr0.5Ti0.5O3/PbZr0.4Ti0.6O3/air can be used for a planar optical waveguide. © 2004 American Vacuum Society.
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77.84.Ek Niobates and tantalates
77.84.Cg PZT ceramics and other titanates
61.05.cp X-ray diffraction
42.79.Gn Optical waveguides and couplers

Use of gas-phase ethanol to mitigate extreme UV/water oxidation of extreme UV optics

L. E. Klebanoff, M. E. Malinowski, W. M. Clift, C. Steinhaus, and P. Grunow

J. Vac. Sci. Technol. A 22, 425 (2004); http://dx.doi.org/10.1116/1.1649344 (8 pages) | Cited 8 times

Online Publication Date: 20 February 2004

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A technique is described that uses a gas-phase species to mitigate the oxidation of a Mo/Si multilayer optic caused by either extreme UV (EUV) or electron-induced dissociation of adsorbed water vapor. It is found that introduction of ethanol (EtOH) into a water-rich gas-phase environment inhibits oxidation of the outermost Si layer of the Mo/Si EUV reflective coating. Auger electron spectroscopy, sputter Auger depth profiling, EUV reflectivity, and photocurrent measurements are presented that reveal the EUV/water- and electron/water-derived optic oxidation can be suppressed at the water partial pressures used in the tests (∼2×10−7–2×10−5 Torr). The ethanol appears to function differently in two time regimes. At early times, ethanol decomposes on the optic surface, providing reactive carbon atoms that scavenge reactive oxygen atoms before they can oxidize the outermost Si layer. At later times, the reactive carbon atoms form a thin (∼5 Å), possibly self-limited, graphitic layer that inhibits water adsorption on the optic surface. © 2004 American Vacuum Society.
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85.40.Hp Lithography, masks and pattern transfer
82.65.+r Surface and interface chemistry; heterogeneous catalysis at surfaces
42.79.Wc Optical coatings

Mitigation of accumulated electric charge by deposited fluorocarbon film during SiO2 etching

Tadashi Shimmura, Yuya Suzuki, Sinnosuke Soda, Seiji Samukawa, Mitsumasa Koyanagi, and Kazuhiro Hane

J. Vac. Sci. Technol. A 22, 433 (2004); http://dx.doi.org/10.1116/1.1649347 (4 pages) | Cited 10 times

Online Publication Date: 20 February 2004

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SiO2 contact-hole etching with a high-aspect ratio is a key process in fabricating ultra-large scale integrated devices. However, charge accumulation in contact holes during plasma etching causes serious problems, such as charge-build-up damage, etching-stop, and microloading effects. Therefore, understanding the mechanism behind this electric charge accumulation and controlling the plasma etching processes would be very important to achieve the next-generation semiconductor devices. We found, through our previous research, that deposited fluorocarbon film in contact holes had high electric conductivity because of ion bombardment. In this experiment, we investigated the build up of charging potential during plasma processes by in situ on-wafer monitoring to control charge accumulation in the contact holes. We developed an on-wafer monitoring device to measure the charging potential in SiO2 contact holes (aspect ratio=5.7). The dc potential of the SiO2 contact hole top and bottom surfaces were measured during plasma exposure with/without deposited fluorocarbon film in the holes. The results revealed that the sidewall deposited fluorocarbon film has high electric conductivity that may mitigate electric charge accumulation at the bottom of contact holes during SiO2 etching processes. © 2004 American Vacuum Society.
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81.65.Cf Surface cleaning, etching, patterning
52.77.Bn Etching and cleaning
73.40.Cg Contact resistance, contact potential
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Trace moisture emissions from heated metal surfaces in hydrogen service

Hans H. Funke, Jianlong Yao, and Mark W. Raynor

J. Vac. Sci. Technol. A 22, 437 (2004); http://dx.doi.org/10.1116/1.1641053 (4 pages)

Online Publication Date: 20 February 2004

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The formation of trace moisture by exposure of dry heated surfaces of 316 L stainless-steel, Restek Silcosteel®, and nickel 1/8 in. outer diameter line segments to purified Ar and H2 was studied using atmospheric pressure ionization mass spectrometry at flow rates of 2 slpm. Prior to H2 exposure, adsorbed moisture was removed by heating incrementally to 500 °C in an argon matrix, where the Restek Silcosteel® material released a maximum of 50 ppb moisture at 300 °C and moisture spikes from the Ni and stainless-steel surfaces reached several 100 ppb. Upon exposure to H2, persistent low ppb moisture emissions due to the reduction of surface oxide species were observed at temperatures as low as 100 °C. Spikes at 300–500 °C ranged from ∼100 ppb for the stainless-steel lines to 400 ppb for the Restek Silcosteel® material. The observed moisture emissions have to be considered as a potential contamination source for high-purity processes utilizing H2 purge at elevated temperatures. © 2004 American Vacuum Society.
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68.43.-h Chemisorption/physisorption: adsorbates on surfaces
81.05.Bx Metals, semimetals, and alloys
81.65.-b Surface treatments
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Erratum: “Etch characteristics of CeO2 thin film in Ar/CF4/Cl2 plasma” [J. Vac. Sci. Technol. A 21, 426 (2003)]

Dong-Pyo Kim, Yun-Seong Chang, and Chang-II Kim

J. Vac. Sci. Technol. A 22, 441 (2004); http://dx.doi.org/10.1116/1.1642652 (1 page) | Cited 1 time

Online Publication Date: 20 February 2004

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© 2004 American Vacuum Society.
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99.10.Cd Errata
81.65.Cf Surface cleaning, etching, patterning
79.60.Dp Adsorbed layers and thin films
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