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Growth behaviors of low-pressure metalorganic chemical vapor deposition aluminum silicate films deposited with two kinds of silicon sources: Hexamethyldisilazane and tetraethyl orthosilicate

Dong-Hau Kuo and Po-Yo Chuang

J. Vac. Sci. Technol. A 20, 1511 (2002); http://dx.doi.org/10.1116/1.1446441 (6 pages) | Cited 1 time

Online Publication Date: 5 September 2002

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Amorphous aluminum silicate films with film thicknesses of 0.5–2.7 μm were prepared on silicon substrates by low-pressure metalorganic chemical vapor deposition. This deposition was conducted using aluminum tri-sec-butoxide as the aluminum source and tetraethyl orthosilicate or hexamethyldisilazane as the silicon source. The choice of different silicon sources is based on their reactivity. The study of growth kinetics is based on the variation of growth rate with deposition temperature and reactant input. These two systems showed big differences in growth kinetics and film composition. © 2002 American Vacuum Society.

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81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.A-	Nucleation and growth
61.72.Mm	Grain and twin boundaries

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Growth-controlled cubic zirconia microstructure in zirconia–titania nanolaminates

J. D. DeLoach, C. R. Aita, and C.-K. Loong

J. Vac. Sci. Technol. A 20, 1517 (2002); http://dx.doi.org/10.1116/1.1491266 (8 pages) | Cited 4 times

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Zirconia microstructure selection (phase and crystallographic orientation) was studied in sputter-deposited multilayer films consisting of nanocrystalline ZrO₂ and amorphous TiO₂. The goal was to understand the mechanism for ZrO₂ microstructure selection as a function of nanolaminate architecture (number of interfaces and ZrO₂ and TiO₂ layer thickness) in a growth regime of limited surface diffusion. The results show that there are two competing paths that ZrO₂ microstructure can follow in a ZrO₂–TiO₂ nanolaminate. One path depends upon geometric shadowing resulting in the formation of a columnar morphology within a ZrO₂ layer. This path leads to cubic (220) growth as an intermediate microstructure, and ultimately to the formation of cubic (200) crystallites spanning several bilayers. In this case, ZrO₂ renucleation within a layer is suppressed. The second path depends upon renucleation within a ZrO₂ layer, involving first tetragonal (111) formation, and then the transformation of tetragonal (111) to monoclinic(11-1)-(111), consistent with a finite crystal size effect. The establishment and maintenance of a columnar morphology (and hence, the suppression of renucleation events), ultimately leads to cubic (200) growth, and is consistent with a growth-controlled microstructure selection mechanism. This mechanism appears to strongly depend upon the existence and planar quality of the TiO₂ growth–restart surfaces. © 2002 American Vacuum Society.

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68.65.Ac	Multilayers
61.46.-w	Structure of nanoscale materials
81.15.Cd	Deposition by sputtering

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Ion-enhanced chemical etching of ZrO₂ in a chlorine discharge

Lin Sha, Byeong-Ok Cho, and Jane P. Chang

J. Vac. Sci. Technol. A 20, 1525 (2002); http://dx.doi.org/10.1116/1.1491267 (7 pages) | Cited 30 times

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Chlorine plasma is found to chemically etch ZrO₂ thin films in an electron cyclotron resonance reactor, and the etch rate scaled linearly with the square root of ion energy at high ion energies with a threshold energy between 12–20 eV. The etching rate decreased monotonically with increasing chamber pressures, which corresponds to reduced electron temperatures. Optical emission spectroscopy and quadrupole mass spectrometry were used to identify the reaction etching products. No Zr, O, or ZrCl were detected as etching products, but highly chlorinated zirconium compounds (ZrCl₂, ZrCl₃, and ZrCl₄) and ClO were found to be the dominant etching products. ZrCl₃ was the dominant etching products at low ion energies, while ZrCl₄ became dominant at higher ion energies. This is consistent with greater momentum transfer and enhanced surface chlorination, as determined by x-ray photoelectron spectroscopy, at increased ion energies. Several ion-enhanced chemical reactions are proposed to contribute to the ZrO₂ etching. © 2002 American Vacuum Society.

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77.84.Bw	Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
81.65.Cf	Surface cleaning, etching, patterning
77.55.-g	Dielectric thin films
52.77.Bn	Etching and cleaning
82.80.Dx	Analytical methods involving electronic spectroscopy
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)

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Annealing behavior of a Cs₂O/Cs₂O₂/GaAs(110) surface studied by electron spectroscopy

J. X. Wu, F. Q. Li, J. S. Zhu, M. R. Ji, and M. S. Ma

J. Vac. Sci. Technol. A 20, 1532 (2002); http://dx.doi.org/10.1116/1.1494817 (4 pages) | Cited 4 times

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A Cs₂O/Cs₂O₂ overlayer was prepared by simultaneous oxygen–cesium adsorption on GaAs(110) at room temperature. In situ electron spectroscopy and work function measurements have been used to study the Cs₂O/Cs₂O₂/GaAs surface as a function of annealing temperature. The Cs₂O/Cs₂O₂/GaAs surface exhibits metallic and has a work function value of 0.9 eV. There are Cs–O–Ga, Cs–O–As, As–O, and Ga–O bonds at the interface of Cs₂O₂/GaAs. Annealing facilitates the interfacial reaction and the minimum of the work function (0.7 eV) was observed after annealing at 540 K. After the decomposition of Cs₂O and Cs₂O₂ at 620 K, the surface dominated by the Cs–O–Ga and Cs–O–As species remains negative electron affinity with a work function value of 1.1 eV. For further annealing, the fast Cs desorption is associated with the decomposition of the Cs–O–Ga and Ca–O–As bonds as well as the evaporations of As₂O₃ and CsAsO₂, forming Ga₂O₃. © 2002 American Vacuum Society.

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68.43.Fg	Adsorbate structure (binding sites, geometry)
61.72.Cc	Kinetics of defect formation and annealing
73.30.+y	Surface double layers, Schottky barriers, and work functions
79.60.Dp	Adsorbed layers and thin films

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Semiempirical profile simulation of aluminum etching in a Cl₂/BCl₃ plasma

D. J. Cooperberg, V. Vahedi, and R. A. Gottscho

J. Vac. Sci. Technol. A 20, 1536 (2002); http://dx.doi.org/10.1116/1.1494818 (21 pages) | Cited 19 times

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A semiempirical profile simulator to predict topographic evolution during Cl₂/BCl₃ plasma etching of photoresist patterned Al lines has been developed. Given incident flux distributions, the profile simulator uses a combination of a particle based Monte Carlo algorithm and analytic ray-tracing algorithm for solving feature-scale ion and neutral flux transport, respectively. We use angular and energy distributions for reflected ions that are consistent with experimental observation and molecular dynamic simulations. Etch yields with energy and angular dependence are experimentally determined for physical sputtering and ion-enhanced etching. The spontaneous etch rate of A1 by chlorine and the spontaneous desorption rate of Cl from photoresist are estimated from experimental results. Sticking coefficients for etchant, chlorine, and depositor, CCl_x, and depositing flux are determined by fitting simulated profiles to experimental data. A semiempirical site-balance model is developed to compute the surface coverage of etchant. The reaction probability of neutrals at surfaces is self-consistently determined from the surface coverage at incident location. Competition between etching and deposition on feature sidewalls is modeled. A shock-tracking method is used to advance the profile using computed etch/deposition rates. Simulation results are presented which demonstrate that facet formation, aspect ratio dependent etching, and critical dimension gain, are captured accurately by the calibrated profile simulator. In addition, the calibrated profile simulator along with results of a 2³ design of experiments in which photoresist and Al etch rates were measured on open frame wafers have been used to create a plasma reactor model. The reactor model relates the operational parameters including inductively coupled power, rf bias and gas flow ratio to the flux variables, i.e., Cl flux, ion flux, ion energy, and depositor flux, that are used as inputs to the profile simulator. In this manner, calibration of the profile simulator requires a minimum of high resolution, expensive, patterned wafers. The reactor model so created is shown to be in quantitative agreement with results from the hybrid plasma equipment model (Ref. 1). © 2002 American Vacuum Society.

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81.65.Cf	Surface cleaning, etching, patterning
52.77.Bn	Etching and cleaning
02.70.Uu	Applications of Monte Carlo methods
02.70.Ns	Molecular dynamics and particle methods
07.05.Fb	Design of experiments
85.40.Hp	Lithography, masks and pattern transfer

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Transition layers in metal bilayers produced by pulsed laser deposition in vacuum

A. Tselev, A. Gorbunov, and W. Pompe

J. Vac. Sci. Technol. A 20, 1557 (2002); http://dx.doi.org/10.1116/1.1494813 (9 pages)

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Main processes which accompany the interaction of energetic particles with the substrate and the growing film in the pulsed laser deposition (PLD) in vacuum are considered. The subplantational film growth mode, which is inherent to PLD, results in the formation of diffuse transition layers (TLs) between the individual materials of the substrate and film. It is argued that thermodynamic forces do not play a significant role in formation of TLs at room temperature by PLD in vacuum, and the resulting concentration profile between the individual materials is determined almost purely by ballistic effects. Up to 10 nm thick TLs in Fe/Al and Ag/Co PLD-produced bilayers have been determined by numerical simulations, semiquantitative analysis and experimentally by means of a quartz thickness monitor. The latter technique has been proposed as an in situ method for determination of TLs between the individual materials with different sputtering yields. The concentration profiles of TLs are featured by a steep slope on the substrate side and an up to 10 nm long tail of the underlying material in the upper layer. © 2002 American Vacuum Society.

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81.15.Fg	Pulsed laser ablation deposition
81.15.-z	Methods of deposition of films and coatings; film growth and epitaxy
81.15.Cd	Deposition by sputtering
68.55.A-	Nucleation and growth
75.70.Ak	Magnetic properties of monolayers and thin films

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Generating high-efficiency neutral beams by using negative ions in an inductively coupled plasma source

Seiji Samukawa, Keisuke Sakamoto, and Katsunori Ichiki

J. Vac. Sci. Technol. A 20, 1566 (2002); http://dx.doi.org/10.1116/1.1494820 (8 pages) | Cited 60 times

Online Publication Date: 5 September 2002

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To minimize radiation damage caused by charge buildup or ultraviolet and x-ray photons during etching, we developed a high-performance neutral-beam etching system. The neutral-beam source consists of an inductively coupled plasma (ICP) source and parallel top and bottom carbon plates. The bottom carbon plate has numerous apertures for extracting neutral beams from the plasma. When a direct current (dc) bias is applied to the top and bottom plates, the generated positive or negative ions are accelerated toward the bottom plate. Most of them are then efficiently converted into neutral atoms, either by neutralization in charge-transfer collisions with gas molecules during ion transport and with the aperture sidewalls in the bottom plate, or by recombination with low-energy electrons near the end of the bottom plate. We found that negative ions are more efficiently converted into neutral atoms than positive ions. The neutralization efficiency of negative ions was almost 100%, and the maximum neutral flux density was equivalent to 4.0 mA/cm². A neutral beam can thus be efficiently produced from the ICP source and apertures in our new neutral-beam source. © 2002 American Vacuum Society.

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52.59.Tb	Moderate-intensity beams
07.77.Gx	Atomic and molecular beam sources and detectors
52.77.Bn	Etching and cleaning

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Redeposition of etch products on sidewalls during SiO₂ etching in a fluorocarbon plasma. I. Effect of particle emission from the bottom surface in a CF₄ plasma

Jae-Ho Min, Sung-Wook Hwang, Gyeo-Re Lee, and Sang Heup Moon

J. Vac. Sci. Technol. A 20, 1574 (2002); http://dx.doi.org/10.1116/1.1494819 (8 pages) | Cited 19 times

Online Publication Date: 5 September 2002

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The effect of etch-product redeposition on sidewall properties during the etching of step-shaped SiO₂ patterns in a CF₄ plasma was examined using a Faraday cage located in a transformer coupled plasma etcher. Sidewall properties were observed for two cases: with and without particles emitted from the bottom surface in normal contact with the sidewall. Particles sputtered from the bottom surface were redeposited on the sidewall, which contributes to the formation of a passivation layer on the surface of the latter. The passivation layer consisted of silicon oxide, Si_xO_y, and fluorocarbon, C_xF_y, the latter comprising the major species. Ar plasma experiments confirmed that C_xF_y or a fluorocarbon polymer must be present on the sidewall in order for the Si_xO_y species to be deposited on the surface. The redeposited particles, which were largely F-deficient fluorocarbon species, as evidenced by x-ray photoelectron spectroscopy analyses, functioned as precursors for fluorocarbon polymerization, resulting in a rough sidewall surface. The chemical etch rates of SiO₂ were retarded by the redeposition of particles, which eventually formed a thick layer, eventually covering the bulk SiO₂. Auger electron spectroscopy analyses of the sidewall surface affected by the emission from the bottom suggest that the surface consists of three distinct layers: a surface-carbon layer, a redeposition-etch combined layer, and bulk SiO₂. © 2002 American Vacuum Society.

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52.77.Bn	Etching and cleaning
81.65.Cf	Surface cleaning, etching, patterning
81.65.Rv	Passivation
79.60.Bm	Clean metal, semiconductor, and insulator surfaces
79.20.Fv	Electron impact: Auger emission

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Thermal decomposition pathway and desorption study of isopropanol and tert-butanol on Si(100)

Jaehyun Kim, Kwansoo Kim, and Kijung Yong

J. Vac. Sci. Technol. A 20, 1582 (2002); http://dx.doi.org/10.1116/1.1494815 (5 pages) | Cited 5 times

Online Publication Date: 5 September 2002

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Thermal decomposition pathway and desorption of isopropanol (IPA) and tert-butanol on Si(100) were studied using temperature programed desorption. Adsorbed alcohols studied were decomposed into atomic hydrogen and alkoxy on the surface. During heating the sample up to 1000 K, acetone, propylene, and hydrogen were desorbed as decomposition products of IPA on Si(100). Desorption pathways of IPA on Si(100) were largely consistent with those on metal surfaces: β-hydride elimination reaction to acetone and C–O scission to propylene. For tert-butanol, which has no β-hydrogen, isobutene and hydrogen were observed as main desorption products. © 2002 American Vacuum Society.

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68.43.Vx	Thermal desorption
82.30.Lp	Decomposition reactions (pyrolysis, dissociation, and fragmentation)

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Optimized oxygen plasma etching of polyimide films for low loss optical waveguides

Navnit Agarwal, Shom Ponoth, Joel Plawsky, and P. D. Persans

J. Vac. Sci. Technol. A 20, 1587 (2002); http://dx.doi.org/10.1116/1.1494816 (5 pages) | Cited 15 times

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Sidewall roughness in waveguides is one of the consequences of a reactive ion etch (RIE) step. Sidewall roughness increases scattering losses and can impediment the scaling of waveguide dimensions to on-chip levels. This article presents results from our experiments on the study of optimal RIE conditions to minimize roughness on waveguide sidewalls. Roughness in planar polyimide films was studied for different plasma etch conditions to obtain an understanding of how roughness evolves. Pressure was found to be the dominant factor affecting interface roughness. RIE done at lower pressures was found to increase the roughness on the film surface. We propose that the roughness produced depends on the angle of incidence of the etchant species with respect to the surface the more obliquely the etchant species were incident on the surface, the lower was the roughness produced. Roughness produced on waveguide sidewalls was studied by measuring their propagation loss. For sidewalls, lower pressure RIE resulted in smoother sidewalls. This result was correlated with the previously obtained results for thin film surfaces. Based on our experiments we propose low pressure RIE to minimize sidewall roughness and fabricate low loss optical waveguides. © 2002 American Vacuum Society.

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42.79.Gn	Optical waveguides and couplers
52.77.Bn	Etching and cleaning
81.65.Cf	Surface cleaning, etching, patterning
42.70.Jk	Polymers and organics

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Two-directional N₂ desorption in thermal dissociation of N₂O on Rh(110), Ir(110), and Pd(110) at low temperatures

H. Horino, I. Rzeźnicka, A. Kokalj, I. Kobal, Y. Ohno, A. Hiratsuka, and T. Matsushima

J. Vac. Sci. Technol. A 20, 1592 (2002); http://dx.doi.org/10.1116/1.1495507 (5 pages) | Cited 14 times

Online Publication Date: 5 September 2002

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Two-directional N₂ desorption was found in N₂O dissociation on Rh(110), Ir(110), and Pd(110) below 160 K by angle-resolved thermal desorption. N₂O(a) is mostly dissociated during heating procedures, emitting N₂(g) and leaving O(a). N₂ showed four desorption peaks in the temperature range of 110–200 K. One of them commonly showed a cosine distribution, whereas the others sharply collimated off the surface normal in the plane along the [001] direction. The collimation angle was about 70° on Rh(110), 65° on Ir(110), and 43°–50° on Pd(110). A high-energy-atom assisted desorption model was proposed for N₂ inclined emission. © 2002 American Vacuum Society.

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68.43.Vx	Thermal desorption
82.30.Lp	Decomposition reactions (pyrolysis, dissociation, and fragmentation)

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Giant polarization in organic heterostructures

Ilja Thurzo, Thorsten U. Kampen, and Dietrich R. T. Zahn

J. Vac. Sci. Technol. A 20, 1597 (2002); http://dx.doi.org/10.1116/1.1495508 (6 pages) | Cited 3 times

Online Publication Date: 5 September 2002

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Deep levels or polarization effects can influence the charge transport through organic layers. Both effects can be identified by charge deep-level transient spectroscopy (Q-DLTS). Here, deep levels or polarization effects cause the charge transient signal Q(t) to be dependent or independent on the bias voltage, respectively. Q-DLTS, accompanied by feedback charge capacitance (FCM) measurements, has been used in the present work to investigate an organic heterostructure grown on an inorganic semiconductor. GaAs(100) substrates (n=0.34×10¹⁸ cm⁻³) were sulfur passivated by wet chemical etching and additional annealing under ultrahigh vacuum (UHV) conditions. Organic molecular beam deposition was used for the growth of 20 nm of 3,4,9,10-perylenetetracarboxilic dianhydride (PTCDA, Lancaster) and 27 nm of tris-(8-hydroxyquinoline) aluminum (Alq3, Syntec). Silver was evaporated on the Alq3 film through a shadow mask resulting in an array of circular contacts with an area of A=2.1×10⁻⁷ m². The back contact to the GaAs(100) was achieved by an In–Ga alloy resulting in a series resistance of 20 Ω. The electrical characterizations were done at room temperature and in situ in the UHV system. The Q-DLTS measurements show a well resolved maximum in Q(t). The amplitude remains almost constant as a function of the bias voltage, which is a clear indication of a polarization in the organic heterostructure. From the experimental results the permittivity dispersion is determined to 2.37. The permittivity dispersion is independently obtained from FCM measurements. With the experimentally determined excess capacitance ΔC of 90 pF and the thickness of the organic heterostructure the permittivity dispersion is determined to 2.42. The FCM scans show no hysteresis due to the absence of deep levels. The ΔC/C=1 presented here clearly indicates the presence of a giant polarization. © 2002 American Vacuum Society.

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73.40.Lq	Other semiconductor-to-semiconductor contacts, p-n junctions, and heterojunctions
71.55.Ht	Other nonmetals
81.65.Rv	Passivation
77.22.Ch	Permittivity (dielectric function)

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Diode laser measurements of CF_x species in a low-pressure, high-density plasma reactor

M. E. Littau, M. J. Sowa, and J. L. Cecchi

J. Vac. Sci. Technol. A 20, 1603 (2002); http://dx.doi.org/10.1116/1.1495510 (8 pages) | Cited 3 times

Online Publication Date: 5 September 2002

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We have developed and used an infrared diode laser absorption spectroscopy diagnostic to measure concentrations of fluorocarbon radicals, including CF, CF₂, and CF₃, during selective oxide etching with a low-pressure, high-density plasma reactor. The fluorocarbon radicals are the precursors for the etch process, as well as for the protective polymer that provides selectivity to the nonoxidized materials. The ability to measure the radical concentrations is important for developing a reproducible oxide etch process. We utilize wavelength modulation to increase the detection sensitivity for operation at the low pressures used in high-density plasma reactors. We use a N₂O reference cell to provide wavelength calibration, facilitating identification of the fluorocarbon absorption lines. The N₂O cell also provides actinometric calibration, which allows us to compare measurements under different experimental conditions and at different times. We present measurements in an inductively coupled plasma (ICP) etch tool comparing CF_x=1–3 concentrations in CFH₃:Ar to those in a C₂F₆:H₂:Ar chemistry. We also present measurements of the rotational temperature of CF₂, which is an essential parameter for extracting concentration measurements from the diode laser measurements. © 2002 American Vacuum Society.

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81.65.Cf	Surface cleaning, etching, patterning
82.33.Xj	Plasma reactions (including flowing afterglow and electric discharges)
52.70.Kz	Optical (ultraviolet, visible, infrared) measurements
52.77.Bn	Etching and cleaning
78.30.Jw	Organic compounds, polymers
06.20.F-	Units and standards

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X-ray photoelectron spectroscopy study of two nitrogen-containing polymer surfaces metallized by nickel

Philippe Bébin and Robert E. Prud’homme

J. Vac. Sci. Technol. A 20, 1611 (2002); http://dx.doi.org/10.1116/1.1495511 (10 pages) | Cited 1 time

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The metallization of polyacrylonitrile (PAN), poly(styrene-co-acrylonitrile) (SAN) and polystyrene (PS) by nickel has been investigated by x-ray photoelectron spectroscopy. Even if there is no significant loss of chemical elements during the metallization process, surface degradation is systematically seen by the presence of amorphous carbon at the interfaces. Nickel oxidation is detected by the presence of metal nitride (with PAN and SAN) and its concentration is directly proportional to the initial nitrogen concentration in the substrates. The analysis of metallized polymer surfaces exposed to air indicates that the changes induced at the surface of the polymer by the nickel condensation are irreversible and suggests the presence of a real metal nitride at the interface. The behavior of SAN under metallization is the sum of the behavior of PS and PAN; this copolymer can merely be represented as a mixture of styrene and acrylonitrile repeat units with no particular effect due to their distribution in the macromolecular chain. © 2002 American Vacuum Society.

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81.65.Mq	Oxidation
81.05.Lg	Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
85.40.Ls	Metallization, contacts, interconnects; device isolation
68.35.Dv	Composition, segregation; defects and impurities
61.41.+e	Polymers, elastomers, and plastics
79.60.Fr	Polymers; organic compounds
68.37.Xy	Scanning Auger microscopy, photoelectron microscopy
68.35.Ct	Interface structure and roughness

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Performance characteristics of single-stage disk-type drag pump

Joong-Sik Heo and Young-Kyu Hwang

J. Vac. Sci. Technol. A 20, 1621 (2002); http://dx.doi.org/10.1116/1.1495512 (11 pages) | Cited 2 times

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The direct simulation Monte Carlo (DSMC) method is applied to investigate steady and unsteady flow fields of a single-stage disk-type drag pump. Two different kinds of pumps are considered: the first one is a rotor–rotor combination, and the second one is a rotor–stator combination. Each of rotor and stator has 10 Archimedes’ spiral blades, respectively. In the present DSMC method, the variable hard sphere molecular model with the no time counter technique is employed to simulate the molecular collision kinetics. For simulation of diatomic gas flows, the Borgnakke–Larsen phenomenological model is adopted to redistribute the translational and internal energies. Some experimental works are carried out to verify the numerical results. Good agreement between the numerical results and the experimental data is shown. © 2002 American Vacuum Society.

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07.30.Cy

Vacuum pumps

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W and WC layers deposition by shielded inductively coupled plasma source

P. Colpo, T. Meziani, P. Sauvageot, G. Ceccone, P. N. Gibson, F. Rossi, and P. Monge-Cadet

J. Vac. Sci. Technol. A 20, 1632 (2002); http://dx.doi.org/10.1116/1.1495509 (7 pages) | Cited 4 times

Online Publication Date: 5 September 2002

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Tungsten and carbon tungsten films have been deposited by a plasma enhanced chemical vapor deposition (PECVD) technique. The plasma-assisted deposition was performed by inductively coupled plasma source (ICP). A Faraday shield was arranged within the plasma chamber to prevent electrically conductive film deposition on the dielectric chamber wall that would screen the electromagnetic field. External electrical parameters and ion densities of the shielded inductive plasma source are measured and compared to classical ICPs source characteristics. Tungsten deposition has been performed from WF₆ diluted in argon and hydrogen. A deposition rate of 5 μm/h was obtained. Hardness measurements show that the tungsten hardness can be increased from 5 to 20 GPA by biasing the substrate. WC films were deposited by adding methane or acetylene to the WF₆/H₂ mixture. The hardness of the WC films depends strongly on the methane or acetylene flow rate, i.e., on the film carbon content. The WC hardness has been correlated to the crystallographic structure. The first hardness maximum peak corresponds to a solid solution of carbon in the tungsten. Correlation between the deposition parameters, such as the gas composition, dc bias and coating properties has been investigated by means of AES, XRD, and nanoindentation analysis. © 2002 American Vacuum Society.

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81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.60.Bs	Mechanical and acoustical properties
52.77.Dq	Plasma-based ion implantation and deposition
52.70.-m	Plasma diagnostic techniques and instrumentation
68.55.A-	Nucleation and growth
62.20.Qp	Friction, tribology, and hardness
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
62.20.M-	Structural failure of materials

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Structure and properties of carbon nitride thin films synthesized by nitrogen-ion-beam-assisted pulsed laser ablation

Z. Y. Chen, J. P. Zhao, T. Yano, T. Shinozaki, and T. Ooie

J. Vac. Sci. Technol. A 20, 1639 (2002); http://dx.doi.org/10.1116/1.1496781 (5 pages) | Cited 4 times

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Carbon nitride films were deposited by pulsed KrF excimer laser ablation of graphite with assistance of low energy nitrogen-ion-beam bombardment. The nitrogen to carbon ratio, bonding state, microstructure, and surface morphology of the deposited carbon nitride films were characterized by x-ray photoelectron spectroscopy (XPS), Fourier-transform infrared (FTIR) spectroscopy, micro-Raman spectroscopy, and atomic force microscopy, respectively. The irradiation effect of the nitrogen ion beam with various ion currents on the synthesis of carbon nitride films was investigated. XPS and FTIR analyses indicate that the bonding state between carbon and nitrogen in the deposited films is influenced by nitrogen irradiation with different ion currents during deposition. The carbon–nitrogen bonding of C–N and C�N is observed in the films. High nitrogen ion current is proposed to promote the desired N–sp³C bonds, i.e., the C₃N₄ phase. In addition, tribological properties of the carbon nitride films deposited on TiN coated stainless steel substrates were also studied in both dry and oil environments, which exhibits a low friction coefficient compared with hard TiN film. © 2002 American Vacuum Society.

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81.15.Fg	Pulsed laser ablation deposition
81.15.Jj	Ion and electron beam-assisted deposition; ion plating
68.55.-a	Thin film structure and morphology
68.60.Bs	Mechanical and acoustical properties
61.80.Jh	Ion radiation effects
61.82.Ms	Insulators
79.60.Bm	Clean metal, semiconductor, and insulator surfaces
68.35.B-	Structure of clean surfaces (and surface reconstruction)
78.30.Hv	Other nonmetallic inorganics
78.66.Nk	Insulators
62.20.Qp	Friction, tribology, and hardness

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Structural study on (CH₃)₂S/Cu(100) by near edge x-ray absorption fine structure and x-ray photoelectron spectroscopy

S. Yagi, Y. Nakano, E. Ikenaga, S. A. Sardar, J. A. Syed, K. Soda, E. Hashimoto, K. Tanaka, and M. Taniguchi

J. Vac. Sci. Technol. A 20, 1644 (2002); http://dx.doi.org/10.1116/1.1496782 (3 pages) | Cited 8 times

Online Publication Date: 5 September 2002

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We have investigated the (CH₃)₂S/Cu(100) system using polarization dependent S K-edge near edge x-ray absorption fine structure (NEXAFS) and x-ray photoelectron spectroscopy (XPS) for both S 1s and C 1s electrons. From the XPS results, the (CH₃)₂S molecule is found to adsorb through the sulfur atom on the Cu(100) surface. There is a little polarization dependence in the S K-edge NEXAFS spectra for submonolayer phase. The orientation angle of the molecular plane is estimated to be 33° from the surface. © 2002 American Vacuum Society.

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68.43.Fg	Adsorbate structure (binding sites, geometry)
78.70.Dm	X-ray absorption spectra
79.60.Dp	Adsorbed layers and thin films

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Helium permeation through a-C:H films deposited on polymeric substrates

L. Valentini, M. C. Bellachioma, L. Lozzi, S. Santucci, and J. M. Kenny

J. Vac. Sci. Technol. A 20, 1647 (2002); http://dx.doi.org/10.1116/1.1497177 (6 pages) | Cited 6 times

Online Publication Date: 5 September 2002

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The influence of amorphous hydrogenated carbon a-C:H coatings on gas permeation through polymer films was investigated. Hydrogenated amorphous carbon (a-C:H) films were deposited, at room temperature, from a CH₄/Ar plasma produced by a radio frequency glow discharge system at 13.56 MHz. Polyether–etherketone (PEEK) and polyetherimide foils with different thicknesses were used as substrates. The permeation of He was measured and the reduction of the permeability coefficient is correlated here to the composition and density of the a-C:H films. The density and film structure of the layers were analyzed using x-ray reflectivity and Raman spectroscopy of films deposited onto silicon reference samples. A less pronounced reduction of the permeability coefficients for hard, dense diamond-like layers is reported with respect to those obtained for soft, polymer-like layers on PEEK substrates. Surprisingly, the barrier efficacy of the coating decreases with an increase in a-C:H film density. This unexpected result is attributed to intrinsic stress and the corresponding formation of microcracks. The effect of nitrogen incorporation, which reduces film permeability, is investigated in terms of the stress relaxation mechanism promoted. © 2002 American Vacuum Society.

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66.30.J-	Diffusion of impurities
81.05.U-	Carbon/carbon-based materials
68.55.-a	Thin film structure and morphology
68.60.Bs	Mechanical and acoustical properties
78.66.Jg	Amorphous semiconductors; glasses
61.43.Dq	Amorphous semiconductors, metals, and alloys
62.40.+i	Anelasticity, internal friction, stress relaxation, and mechanical resonances
81.40.Jj	Elasticity and anelasticity, stress-strain relations
81.40.Np	Fatigue, corrosion fatigue, embrittlement, cracking, fracture, and failure
62.20.M-	Structural failure of materials
78.35.+c	Brillouin and Rayleigh scattering; other light scattering

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Abnormal room-temperature oxidation of silicon in the presence of copper

Kenji Hinode, Ken’ichi Takeda, and Seiichi Kondo

J. Vac. Sci. Technol. A 20, 1653 (2002); http://dx.doi.org/10.1116/1.1497179 (6 pages) | Cited 2 times

Online Publication Date: 5 September 2002

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The room-temperature reaction between copper (Cu) and silicon (Si) was investigated. The areas of an Si substrate covered with very thin or island-like Cu oxidized formed thick (>100 nm) oxide (SiO₂). The areas covered with thick and nonisland-like Cu film did not. These unoxidized areas transformed into SiO₂ when the side surfaces of the sample were exposed to air after sectioning for transmission electron microscope observation. The supply of oxygen was found to control this oxidation process. The presence of a Cu silicide, such as Cu₃Si, was found to not necessarily be needed for oxidation. The oxidation rate estimated from observation was about 150 nm/month. Copper atoms were detected at the SiO₂/Si interface and identified not as silicides but as body-center-cubic-structured Cu several atom layers thick. © 2002 American Vacuum Society.

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81.65.Mq	Oxidation
68.37.Lp	Transmission electron microscopy (TEM)

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Effects of bridge pattern on performance of YBaCuO microbolometers

P. Laou and L. Ngo Phong

J. Vac. Sci. Technol. A 20, 1659 (2002); http://dx.doi.org/10.1116/1.1496784 (4 pages)

Online Publication Date: 5 September 2002

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The effects of bridge pattern on the performance of YBaCuO microbolometers were investigated. For this purpose, Si₃N₄ bridges with grids and hinges of varying width were created on Si wafers by means of bulk Si micromachining. Semiconducting YBaCuO films were sputter-deposited onto the bridges to form resistive bolometers. In reducing the width of the hinges from 10 to 5 μm, one can enhance the bolometric responsivity by approximately two times at room temperature. Further, a factor of enhancement of as large as three could be achieved on bridges with a grid pattern. The grid pattern also modified the spectral absorbance of the bridges. The enhancement of experimental responsivity was shown to be consistent with the one predicted from changes in thermal conductance, electrical resistance, and optical absorbance of the bolometers. © 2002 American Vacuum Society.

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07.57.Kp	Bolometers; infrared, submillimeter wave, microwave, and radiowave receivers and detectors
85.60.Gz	Photodetectors (including infrared and CCD detectors)
07.07.Df	Sensors (chemical, optical, electrical, movement, gas, etc.); remote sensing
85.85.+j	Micro- and nano-electromechanical systems (MEMS/NEMS) and devices
07.10.Cm	Micromechanical devices and systems

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Secondary ion mass spectrometry induced damage adjacent to analysis craters in silicon

M. H. Clark, K. S. Jones, and F. A. Stevie

J. Vac. Sci. Technol. A 20, 1663 (2002); http://dx.doi.org/10.1116/1.1497178 (4 pages) | Cited 2 times

Online Publication Date: 5 September 2002

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Damage introduced by dynamic secondary ion mass spectrometry (SIMS) depth profiling is studied. A silicon sample with a boron marker layer was depth profiled by dynamic SIMS. After subsequent annealing at 750 °C for 30 min, the SIMS sample was reanalyzed by plan-view transmission electron microscope (PTEM) and SIMS. PTEM images showed the presence of interstitial defects near the original SIMS crater, and SIMS depth profiles of similar regions exhibited boron diffusivity enhancements. Excess interstitials were introduced into the Si surface up to 2 mm from the original 225 μm×225 μm crater. Both PTEM and SIMS results showed that the damage and its effects diminished with an increase in distance from the original crater. © 2002 American Vacuum Society.

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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)
61.72.S-	Impurities in crystals
81.70.Jb	Chemical composition analysis, chemical depth and dopant profiling
61.72.Cc	Kinetics of defect formation and annealing
61.72.J-	Point defects and defect clusters
66.30.J-	Diffusion of impurities

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P. A. Redhead

J. Vac. Sci. Technol. A 20, 1667 (2002); http://dx.doi.org/10.1116/1.1496783 (9 pages) | Cited 7 times

Online Publication Date: 5 September 2002

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This document recommends a set of uniform procedures for the reporting of outgassing data. Its intention is to establish a consistent set of units, nomenclature, methods of data presentation, and certain experimental parameters in order that outgassing data from different sources is consistently reported so as to be useful to all. This document was prepared by a subcommittee of the Recommend Practices Committee of the American Vacuum Society and is an updating of a previous Recommended Practice published in 1965. © 2002 American Vacuum Society.

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07.30.Bx	Degasification, residual gas
07.05.Rm	Data presentation and visualization: algorithms and implementation
06.20.F-	Units and standards

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Chemical structure of ultrathin SiO₂ film with nitrogen incorporated by remote nitrogen plasma

M.-H. Cho, Y. S. Roh, C. N. Whang, K. Jeong, D.-H. Ko, J. Y. Yoo, N. I. Lee, and K. Fujihara

J. Vac. Sci. Technol. A 20, 1676 (2002); http://dx.doi.org/10.1116/1.1497991 (6 pages) | Cited 4 times

Online Publication Date: 5 September 2002

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The nitrided ultrathin SiO₂ films using a remote nitrogen plasma source were investigated by high-resolution x-ray photoelectron spectroscopy. At the low nitridation temperature of 500 °C, the nitrogen is effectively incorporated in 15 Å SiO₂ film. The chemical shifts of the N 1s peaks show that the quantity of the second-nearest neighbors of oxygen atoms and N–O bonds influences the difference of the peak shift depending on the nitridation temperature and post-annealing in ultrahigh vacuum. The peak intensity changes of the N 1s peak at the different take-off angles indicate that the nitridation dominantly occurs at the interfacial region as the nitridation temperature increases, which suggests that the highly incorporated nitrogen at the surface region can be accomplished even with a low temperature nitridation process using a remote nitrogen plasma source. The defect formation due to the nitrogen incorporation resulted in a negative shift of the capacitance–voltage curve, and the difference is increased as the nitridation temperature is elevated. © 2002 American Vacuum Society.

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68.55.-a	Thin film structure and morphology
81.65.Lp	Surface hardening: nitridation, carburization, carbonitridation
52.77.-j	Plasma applications
79.60.Bm	Clean metal, semiconductor, and insulator surfaces
61.72.Cc	Kinetics of defect formation and annealing

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Microstructure, chemistry, and tribological performance of MoS_x/WSe_y co-sputtered composites

A. Savan, H. Haefke, M. C. Simmonds, and C. P. Constable

J. Vac. Sci. Technol. A 20, 1682 (2002); http://dx.doi.org/10.1116/1.1497990 (8 pages) | Cited 4 times

Online Publication Date: 5 September 2002

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Co-sputtered thin films have been deposited from MoS₂ and WSe₂ targets in order to investigate the relationships between tribological behavior and film microstructure. The stoichiometries of pure films for the sputtering conditions used, were found to be MoS_1.6 and WSe_1.5 as measured by wavelength dispersive x-ray analysis. The mechanical properties of the composite films were investigated by pin-on-disk wear testing in 50% relative humidity air as a function of WSe₂ concentration. X-ray diffraction measurements indicate that the microstructure is strongly affected by the inclusion of WSe₂ and there is a strong correlation between microstructure and tribological performance. X-ray and Raman measurements indicate a large increase in the c axis of the MoS₂, which may be due to intercalation. X-ray photoelectron spectroscopy measurements show no evidence that either Se or W chemically substitutes into the MoS₂ structure. © 2002 American Vacuum Society.

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68.55.-a	Thin film structure and morphology
81.15.Cd	Deposition by sputtering
81.70.-q	Methods of materials testing and analysis
68.35.Gy	Mechanical properties; surface strains
81.40.Pq	Friction, lubrication, and wear
62.20.Qp	Friction, tribology, and hardness
68.55.A-	Nucleation and growth
68.55.Nq	Composition and phase identification
78.30.Hv	Other nonmetallic inorganics
78.66.Nk	Insulators

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Reactivity of Cu with poly(tetrafluoroethylene) and poly(vinyl chloride): Effect of pre- and post-metallization modification on the metal/polymer interface

C. C. Perry, J. Torres, S. R. Carlo, and D. Howard Fairbrother

J. Vac. Sci. Technol. A 20, 1690 (2002); http://dx.doi.org/10.1116/1.1497989 (9 pages) | Cited 3 times

Online Publication Date: 5 September 2002

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The reactivity of Cu with poly(tetrafluoroethylene) (PTFE) and poly(vinylchloride) (PVC) during thermal evaporation, as well as the effect of pre- and post-metallization Ar⁺ ion and x-ray mediated surface modification treatments on the metal/polymer interface, have been studied using in situ x-ray photoelectron spectroscopy (XPS) and ex situ atomic force microscopy (AFM). During thermal evaporation, copper was unreactive on PTFE but reacted with PVC to form CuCl. Pretreatment of PTFE or PVC surfaces by Ar⁺ ion or x-ray irradiation did not modify the chemical reactivity of the polymer surface during subsequent Cu deposition, although significant morphological changes were observed on PTFE by AFM. In contrast, post-metallization modification of the Cu/PTFE interface by Ar⁺ ion or x-ray irradiation lead to the production of CuF₂, and increased the yield of CuCl in the Cu/PVC system. In either the Cu/PTFE or Cu/PVC systems, the maximum concentration of copper halide formed and dependence upon treatment time was found to be similar for either Ar⁺ ion or x-ray irradiation post-metallization treatment strategies, suggesting a common reaction mechanism. © 2002 American Vacuum Society.

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82.35.Gh	Polymers on surfaces; adhesion
82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces
82.35.-x	Polymers: properties; reactions; polymerization
81.05.Lg	Polymers and plastics; rubber; synthetic and natural fibers; organometallic and organic materials
85.40.Ls	Metallization, contacts, interconnects; device isolation
61.80.Jh	Ion radiation effects
61.80.Cb	X-ray effects
81.65.-b	Surface treatments
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
79.60.Jv	Interfaces; heterostructures; nanostructures
82.20.-w	Chemical kinetics and dynamics
68.37.Ps	Atomic force microscopy (AFM)
68.37.Xy	Scanning Auger microscopy, photoelectron microscopy

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Reactive sputter deposition of tungsten nitride thin films

Colin C. Baker and S. Ismat Shah

J. Vac. Sci. Technol. A 20, 1699 (2002); http://dx.doi.org/10.1116/1.1498278 (5 pages) | Cited 8 times

Online Publication Date: 5 September 2002

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Tungsten nitride (WN_x) thin films were deposited by reactively sputtering a pure W target in an argon/nitrogen atmosphere. The nitrogen concentration in the growth chamber was varied from 2% to 60%. Film growth and properties were studied as a function of nitrogen concentration in the films. The cathode current and voltage variations during the film growth indicated cathode poisoning when the nitrogen concentration in the chamber was in the range of 2%–5%. This poisoning was accompanied by a reduced film growth rate. However, both the cathode current and deposition rate decrease were small due to the low resistivity and similar sputter yield of the WN_x phase formed at the surface of the target and pure W. X-ray photoelectron spectroscopy analyses showed that the films were composed of ∼33 at. % nitrogen when the nitrogen concentration in the chamber was greater than 10%. X-ray diffraction (XRD) analysis confirmed that the films were predominantly W₂N with the characteristic (111) peak at 2θ=37.7°. Slight shifts in the (111) peak position were due to excess nitrogen incorporation in interstitial positions, which caused lattice distortions. Postdeposition annealing removed the excess interstitial nitrogen and the XRD peaks shifted closer to the characteristic value. © 2002 American Vacuum Society.

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81.15.Cd	Deposition by sputtering
68.55.Ln	Defects and impurities: doping, implantation, distribution, concentration, etc.
79.60.Dp	Adsorbed layers and thin films
61.72.J-	Point defects and defect clusters
85.40.Ls	Metallization, contacts, interconnects; device isolation

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High-rate deposition of a-SiN_x:H for photovoltaic applications by the expanding thermal plasma

W. M. M. Kessels, J. Hong, F. J. H. van Assche, J. D. Moschner, T. Lauinger, W. J. Soppe, A. W. Weeber, D. C. Schram, and M. C. M. van de Sanden

J. Vac. Sci. Technol. A 20, 1704 (2002); http://dx.doi.org/10.1116/1.1497992 (12 pages) | Cited 16 times

Online Publication Date: 5 September 2002

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Driven by the need for improvement of the economical competitiveness of photovoltaic energy, the feasibility of high-rate (>1 nm/s) amorphous silicon nitride (a-SiN_x:H) deposited by the expanding thermal plasma (ETP) technique has been explored with respect to the application of the a-SiN_x:H as functional antireflection coating on crystalline silicon solar cells. First, the deposition rate and the a-SiN_x:H film properties, such as refractive index, Si, N, and H atomic density, and hydrogen bonding configurations, have been mapped for various operating conditions. From ellipsometry, elastic recoil detection, and infrared spectroscopy, it has been shown that deposition rates up to 20 nm/s can be reached with a fair film homogeneity and that the refractive index and the N/Si ratio can fully be tuned by the plasma composition while the hydrogen content can be controlled by the substrate temperature. Good antireflection coating performance of the a-SiN_x:H has therefore been observed for monocrystalline silicon solar cells. These cells with ETP a-SiN_x:H yielded only slightly lower conversion efficiencies than high-quality reference cells due to a much lower degree of surface passivation. This lack of surface passivation has also been shown in a separate study on the surface recombination velocity. Furthermore, it has been tested whether the a-SiN_x:H films lead to silicon bulk passivation, which is essential for solar cells based on cheaper, defective silicon stock material such as multicrystalline silicon. It has been proven that bulk passivation of the cells is indeed induced by the high-rate ETP deposited a-SiN_x:H after a high-temperature step in which the metal contacts of the cells are processed. These results make the ETP technique an interesting candidate for high-throughput processing of competitive silicon solar cells. © 2002 American Vacuum Society.

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84.60.Jt	Photoelectric conversion
81.65.Rv	Passivation
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
68.55.A-	Nucleation and growth
42.79.Wc	Optical coatings
78.20.Ci	Optical constants (including refractive index, complex dielectric constant, absorption, reflection and transmission coefficients, emissivity)
73.25.+i	Surface conductivity and carrier phenomena
61.43.-j	Disordered solids
79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
52.77.Dq	Plasma-based ion implantation and deposition

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Temperature dependence of oxide decomposition on titanium surfaces in ultrahigh vacuum

Y. Mizuno, F. K. King, Y. Yamauchi, T. Homma, A. Tanaka, Y. Takakuwa, and T. Momose

J. Vac. Sci. Technol. A 20, 1716 (2002); http://dx.doi.org/10.1116/1.1500746 (6 pages) | Cited 10 times

Online Publication Date: 5 September 2002

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It is well known that the surface of titanium forms stable oxides of Ti₂O, TiO, Ti₂O₃, Ti₃O₅, Ti_nO_2n−1 (4<n<38) and TiO₂ and, as a result, the surface exhibits a high degree of immunity against attack by acids and chlorides. However, titanium is also a very active getter. To characterize the gettering process, we have investigated the temperature dependence of stable oxides on titanium in ultrahigh vacuum (UHV) using Auger electron spectroscopy, quadrupole mass spectrometry (QMS), and x-ray photoelectron spectroscopy (XPS) in the temperature range from room temperature (RT) to 600 °C. The surfaces of titanium specimens were prepared by electropolishing (EP), and a thin titanium oxide layer, principally TiO₂, was formed on the surface at RT. On increasing the temperature to above 300 °C, the O_KLL Auger intensity began to decrease in a drastic way, while in contrast, the Ti_LMM Auger intensity was increased. Above 450 °C, no oxygen was detected on the titanium surface in UHV. However, the outgassing rates of H₂O, O₂, CO, and CO₂ from the surface did not show any changes in QMS measurements below 450 °C. This behavior is explained as gettering, which is an enhancement of diffusion of oxygen from the surface into the bulk. To investigate the temperature dependence of the chemical states of titanium oxides on an EP surface, XPS analysis was also performed in the same way in the range of 200–450 °C. The results showed drastic changes of the titanium oxide core XPS levels such that the TiO₂ decomposed into suboxides at 180 °C, and even the remaining TiO₂ was still decreasing on heating up to 420 °C. The surface oxide composition on titanium is very sensitive to the temperature. © 2002 American Vacuum Society.

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81.65.Tx	Gettering
82.65.+r	Surface and interface chemistry; heterogeneous catalysis at surfaces
82.30.Lp	Decomposition reactions (pyrolysis, dissociation, and fragmentation)
68.35.Dv	Composition, segregation; defects and impurities
82.80.Pv	Electron spectroscopy (X-ray photoelectron (XPS), Auger electron spectroscopy (AES), etc.)
82.80.Ms	Mass spectrometry (including SIMS, multiphoton ionization and resonance ionization mass spectrometry, MALDI)
81.65.Mq	Oxidation

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Approach for control of high-density plasma reactors through optimal pulse shaping

Tyrone L. Vincent and Laxminarayan L. Raja

J. Vac. Sci. Technol. A 20, 1722 (2002); http://dx.doi.org/10.1116/1.1501570 (11 pages) | Cited 1 time

Online Publication Date: 5 September 2002

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Increasingly stringent requirements in the manufacture of integrated circuits and microscale devices are demanding new approaches to the design and operation of glow-discharge plasma process reactors. Several approaches have been proposed recently, one of which is the operation of plasma reactors in the pulsed mode where the power input to the reactor is modulated using square-wave pulses (SWPs). In this article, we propose a completely general technique for pulsed operation of plasma reactors where the power input is modulated using pulse shapes that are determined systematically using a computational method. We call this technique optimal pulse shaping (OPS) and it relies on a physical model of the plasma reactor used in conjunction with an optimal control algorithm. The OPS technique enables simultaneous control of several plasma process parameters, thus expanding the accessible plasma parameter space over that achievable by SWPs. We apply the OPS technique to a pure argon high-density plasma reactor. Optimal power input pulse shapes and pulsing frequencies are determined in order to control time-averaged values of the ion number densities, the ratio of metastable-to-ion number densities, and the electron temperatures in the bulk plasma. Results indicate that all optimal power input pulse shapes can be characterized by “on” and “off” periods, with a typical on period consisting of power input spikes accompanied by a lower plateau input. The off period consisting of either a true zero input power or a small input power. The power input spikes during the on period control the averaged ion densities, while the plateau input controls the metastable densities. The average electron temperature is controlled by the off power input. © 2002 American Vacuum Society.

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52.77.Bn	Etching and cleaning
81.65.Cf	Surface cleaning, etching, patterning
85.40.Sz	Deposition technology
07.05.Dz	Control systems
52.77.Dq	Plasma-based ion implantation and deposition
52.80.Hc	Glow; corona

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Advantages of laser-acoustical leak testing for construction and operation of low-temperature installations and superconducting experiments

W. Herz

J. Vac. Sci. Technol. A 20, 1733 (2002); http://dx.doi.org/10.1116/1.1501568 (5 pages)

Online Publication Date: 5 September 2002

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At the Institute of Technical Physics of the Research Center Karlsruhe, superconducting magnets for nuclear fusion applications have been tested in the vacuum tank TOSKA for more than 20 years. A crucial test parameter of the magnet coils (mass up to 120 metric tons) as well as of the peripheral components, such as current leads (up to 80 kA), helium refrigerators (2 kW), and low-temperature transfer lines (length ∼200 m), is their vacuum tightness at operating conditions (minimum temperature ∼2 K, maximum refrigerant pressure 25 bar). Because the final tests at cryotemperature are costly and time consuming, intermediate tests at room temperature have already been performed at the stages of manufacturing, certification, and assembling, and prior to cooldown. So far, these tightness tests have been performed with probe gas helium employing a conventional mass spectrometer leak detector, whereby the smallest detectable leakage is limited by the He partial pressure in the surrounding air. Therefore, a new technique of leak measurement was investigated using the probe gas sulfur hexafluoride SF₆, which does not occur in natural air, and which can be sensitively detected by a laser-acoustical leak detector. The obtained experimental results reveal the substantial advantages of the new method with respect to detection sensitivity, testing expenditure, and costs. The results can be transferred to tightness tests in other fields of technology. © 2002 American Vacuum Society.

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07.30.Hd	Vacuum testing methods; leak detectors
07.20.Mc	Cryogenics; refrigerators, low-temperature detectors, and other low-temperature equipment
28.52.Av	Theory, design, and computerized simulation
84.71.Ba	Superconducting magnets; magnetic levitation devices
43.35.Ud	Thermoacoustics, high temperature acoustics, photoacoustic effect

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Tribological behavior of alumina doped zinc oxide films grown by pulsed laser deposition

S. V. Prasad, J. J. Nainaparampil, and J. S. Zabinski

J. Vac. Sci. Technol. A 20, 1738 (2002); http://dx.doi.org/10.1116/1.1501567 (6 pages) | Cited 4 times

Online Publication Date: 5 September 2002

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Zinc oxide, a well-known piezoelectric material, has become the subject of tribological investigations. This research describes the synthesis and tribological evaluation of alumina doped zinc oxide [ZnO(Al₂O₃]) films grown in vacuum by a pulsed laser deposition (PLD) technique using hot pressed ZnO–5 wt % Al₂O₃ targets. For comparison, pure ZnO films were grown under identical PLD conditions. The films were characterized by scanning electron microscopy, energy dispersive x-ray spectroscopy, x-ray diffraction, and x-ray photoelectron spectroscopy. Friction measurements were made using a ball-on-disk tribometer. Nanotribological studies were conducted on wear scars of ZnO and ZnO(Al₂O₃) films by atomic and lateral force microscopy. Both ZnO and ZnO(Al₂O₃) films were crystalline, with a strong (002) texture. The friction coefficient of the ZnO(Al₂O₃) film (μ=0.15) was considerably less than that of the pure ZnO film (μ=0.34). Wear scars on doped ZnO films were relatively smooth and, unlike in the case of pure ZnO films, no cracks were observed. Lateral force microscopy images of wear scars on ZnO(Al₂O₃) films showed dark contrast regions indicating the presence of a slippery phase. No such phase contrast was observed in the case of pure PLD ZnO film grown in vacuum. © 2002 American Vacuum Society.

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68.60.Bs	Mechanical and acoustical properties
62.20.Qp	Friction, tribology, and hardness
81.15.Fg	Pulsed laser ablation deposition
77.84.Bw	Elements, oxides, nitrides, borides, carbides, chalcogenides, etc.
68.55.-a	Thin film structure and morphology
77.55.-g	Dielectric thin films
68.37.Hk	Scanning electron microscopy (SEM) (including EBIC)
79.60.Bm	Clean metal, semiconductor, and insulator surfaces
68.37.Ps	Atomic force microscopy (AFM)

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Effect of deposition interruption and substrate bias on the structure of sputter-deposited yttria-stabilized zirconia thin films

David E. Ruddell, Brian R. Stoner, and Jeffrey Y. Thompson

J. Vac. Sci. Technol. A 20, 1744 (2002); http://dx.doi.org/10.1116/1.1501573 (5 pages) | Cited 5 times

Online Publication Date: 5 September 2002

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The possibility of altering the morphological structure of radio-frequency magnetron sputter- deposited yttria-stabilized zirconia thin films was studied. A columnar grain structure is often observed in sputter deposited thin films; however, this morphology may not be desirable. Two potential methods of disrupting the columnar grain structure were investigated; deposition interruption and periodic application of a substrate bias. Simple interruption of the deposition process was not effective in altering the columnar grain structure of the sputter-deposited films. The use of a periodic substrate bias produced a laminate structure with alternating layers of distinctly different microstructure. X-ray diffraction showed that as the thickness of the layers decreased (with increasing number of layers), the monoclinic phase was eliminated from the deposited thin films, and the films showed a preference for the (200)_t orientation. © 2002 American Vacuum Society.

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68.55.-a	Thin film structure and morphology
81.15.Cd	Deposition by sputtering
68.37.Hk	Scanning electron microscopy (SEM) (including EBIC)

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Effects of deposition temperature on structural defect and electrical resistivity in heteroepitaxial La_0.5Sr_0.5CoO₃/CeO₂/YSZ/Si films

Chun-Hua Chen, Atsushi Saiki, Naoki Wakiya, Kazuo Shinozaki, and Nobuyasu Mizutani

J. Vac. Sci. Technol. A 20, 1749 (2002); http://dx.doi.org/10.1116/1.1502695 (6 pages)

Online Publication Date: 5 September 2002

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The effects of deposition temperature (500–800 °C) on the structural defect and electrical resistivity of heteroepitaxial La_0.5Sr_0.5CoO₃ (LSCO) films with CeO₂/YSZ double buffer layers on Si(001) substrates have been investigated mainly by high-resolution x-ray diffraction techniques. According to the deposition temperature range, two types of structural defect could be distinguished clearly. In the lower-temperature range of about 500–600 °C, the main defect of LSCO is the mosaic structure with a huge coherent distortion. In the higher range of about 600–800 °C, a distinct lattice constant gradient of LSCO was observed, indicating an occurrence of lattice relaxation when introducing an additional defect type, which are misfit dislocations. A high correlation between the electrical resistivity of LSCO, and the defect type and concentration was found. The distribution of electrical resistivity shows a mosaic dispersion degree dependence in 500–600 °C and a lattice relaxation degree dependence in 700–800 °C, where the mosaic dispersion degree and lattice relaxation degree can be estimated by the full width at half maxima of ω and 2θ/ω scans, respectively. © 2002 American Vacuum Society.

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68.55.Ln	Defects and impurities: doping, implantation, distribution, concentration, etc.
73.61.Le	Other inorganic semiconductors
61.72.Lk	Linear defects: dislocations, disclinations
68.55.-a	Thin film structure and morphology
61.72.Hh	Indirect evidence of dislocations and other defects (resistivity, slip, creep, strains, internal friction, EPR, NMR, etc.)

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Effect of substrate position in i-ZnO thin-film formation to Cu(In,Ga)Se₂ solar cell

Toshiyuki Yamaguchi, Tooru Tanaka, and Akira Yoshida

J. Vac. Sci. Technol. A 20, 1755 (2002); http://dx.doi.org/10.1116/1.1502696 (4 pages) | Cited 5 times

Online Publication Date: 5 September 2002

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Intrinsic ZnO (i-ZnO) thin films were prepared by rf magnetron sputtering of nondoped ZnO targets in Ar gas under various substrate positions and they were applied to solar cells. We have characterized i-ZnO thin films and investigated the solar cell performance. The resistivity and the full width at half maximum (FWHM) in the x-ray diffraction peak were changed, depending on the substrate position. The performance of solar cells was correspondent to the change of the resistivity and the FWHM of the i-ZnO thin films. © 2002 American Vacuum Society.

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84.60.Jt	Photoelectric conversion
68.55.-a	Thin film structure and morphology
73.61.Ga	II-VI semiconductors
81.15.Cd	Deposition by sputtering

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Ion energy distributions versus frequency and ion mass at the rf-biased electrode in an inductively driven discharge

I. C. Abraham, J. R. Woodworth, M. E. Riley, P. A. Miller, T. W. Hamilton, and B. P. Aragon

J. Vac. Sci. Technol. A 20, 1759 (2002); http://dx.doi.org/10.1116/1.1502693 (10 pages) | Cited 12 times

Online Publication Date: 5 September 2002

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In this article, we present ion energy distributions (IEDs) at a rf-biased surface as a function of driving frequency and ion mass. The experiments were carried out in high-density inductively coupled rare-gas (Ne,Ar,Xe) plasmas. Our quadrupole mass and cylindrical-mirror energy analyzer sampled ions incident on a rf-biased pinhole located in the center of the wafer chuck. The electron density, electron temperature, and plasma and chuck potential oscillations were measured, and they provided inputs to numerical models used to predict IEDs, which were shown to closely match our experimental results under certain conditions. For a given driving frequency, heavier ions showed narrower IEDs and, for a given ion mass, the IED became narrower and shifted to a higher mean energy with increased driving frequency, in agreement with calculations. © 2002 American Vacuum Society.

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52.80.-s	Electric discharges
52.77.Bn	Etching and cleaning
52.25.-b	Plasma properties
52.35.Fp	Electrostatic waves and oscillations (e.g., ion-acoustic waves)

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Effects of plasma treatment on the properties of Cu/Ta/fluorinated amorphous carbon (a-C:F)/Si multilayer structure

Sung-Hoon Yang, Heondo Kim, and Jong-Wan Park

J. Vac. Sci. Technol. A 20, 1769 (2002); http://dx.doi.org/10.1116/1.1502694 (5 pages) | Cited 1 time

Online Publication Date: 5 September 2002

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The effects of nitrogen postplasma treatment on the properties of a Cu/Ta/a-C:F structure were investigated. Interface reactions between Ta and a-C:F were also examined. A strong interaction between Ta and a-C:F at the interface and defluorination of a-C:F film occurred during Ta sputter deposition. Ta fluoride was observed at the interface between Ta and a-C:F, which led to adhesion and reliability problems. In order to suppress the reaction at the interface, nitrogen plasma was applied to the as-deposited a-C:F film. The fluorine concentration of the film surface decreases with plasma treatment. As the plasma treatment power increases, the adhesion between Ta and a-C:F film improved. From this study, it was found that nitrogen plasma treatment of a-C:F films is a very effective method for suppression of defluorination of a-C:F film and the interface reaction between Ta and a-C:F film. © 2002 American Vacuum Society.

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81.65.-b	Surface treatments
68.35.Fx	Diffusion; interface formation
68.35.Dv	Composition, segregation; defects and impurities
85.40.Ls	Metallization, contacts, interconnects; device isolation

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Quantitative study of ion bombardment induced phase transformation of cubic boron nitride by reflective electron energy-loss spectroscopy

Y. Y. Hui, K. W. Wong, and W. M. Lau

J. Vac. Sci. Technol. A 20, 1774 (2002); http://dx.doi.org/10.1116/1.1503781 (5 pages) | Cited 2 times

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The phase transformation of cubic boron nitride (c-BN) in the near-surface region of a c-BN (111) facet induced by argon-ion bombardment has been investigated by reflective electron energy-loss spectroscopy, with the objective of tracking possible growth mechanisms of c-BN in ion-assisted vapor deposition. For example, with an ion energy of 500 eV at a fluence of 5×10¹⁶ ions/cm², 74% of c-BN were found transformed to h-BN and a-BN within the ion penetration depth of 11 Å. Lowering the argon ion bombardment energy to 200 eV reduced the phase transformation depth to 7 Å. A damage saturation was observed at a fluence of 6×10¹⁶ ions/cm², at which up to 9% of the cubic phase were transformed. Similar measurements were performed at other ion energies. The present work gives a quantitative explanation of the difficulty in growing pure c-BN films with ion-assisted deposition and the presence of an upper-bound in ion energy above which the formation of phases other than the cubic phase dominate. © 2002 American Vacuum Society.

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79.20.Rf	Atomic, molecular, and ion beam impact and interactions with surfaces
68.35.Rh	Phase transitions and critical phenomena
68.55.-a	Thin film structure and morphology
79.20.Uv	Electron energy loss spectroscopy

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Growth of stoichiometric (002) ZnO thin films on Si (001) substrate by using plasma enhanced chemical vapor deposition

B. S. Li, Y. C. Liu, Z. Z. Zhi, D. Z. Shen, J. Y. Zhang, Y. M. Lu, X. W. Fan, and X. G. Kong

J. Vac. Sci. Technol. A 20, 1779 (2002); http://dx.doi.org/10.1116/1.1503783 (5 pages) | Cited 3 times

Online Publication Date: 5 September 2002

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ZnO thin films have been grown on Si(100) substrate by plasma enhanced chemical vapor deposition using a zinc organic source [Zn(C₂H₅)₂] and carbon dioxide (CO₂) gas mixture at 503 K. The dependence of ZnO thin film quality on the gas flow rate ratio of Zn(C₂H₅)₂ to CO₂ (GFRRZC) is studied by x-ray diffraction (XRD), optical absorption (OA) spectra, and photoluminescence (PL) spectra. An excitonic absorption peak is observed in the OA spectra, which closely depends on the GFRRZCs. The XRD spectra show that a c-axis-orientated wurtzite structure ZnO thin film with the full width at half maximum (FWHM) of 0.24° has been prepared. The PL spectra show a strong UV emission with a narrow FWHM of 105 meV at 3.289 eV with a weak deep-level defect emission around 2.5 eV, implying the formation of the stoichiometric ZnO thin films. The origin of the UV band is from the free exciton recombination testified by the temperature dependent PL spectra. © 2002 American Vacuum Society.

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68.55.-a	Thin film structure and morphology
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
78.66.Hf	II-VI semiconductors
71.35.Cc	Intrinsic properties of excitons; optical absorption spectra
78.55.Et	II-VI semiconductors
78.40.Fy	Semiconductors
71.55.Gs	II-VI semiconductors

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Simple method for cleaning gallium nitride (0001)

Francisco Machuca, Zhi Liu, Yun Sun, P. Pianetta, W. E. Spicer, and R. F. W. Pease

J. Vac. Sci. Technol. A 20, 1784 (2002); http://dx.doi.org/10.1116/1.1503782 (3 pages) | Cited 14 times

Online Publication Date: 5 September 2002

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Achieving clean surfaces is a major and challenging requirement for the study of surfaces and surface reactions. We describe the use of synchrotron radiation (SR) to probe the electronic structure of the gallium nitride (GaN) (0001) surface that has undergone wet chemical cleaning sequences followed by heating. By using SR in the range of 200–1000 eV the core levels of Ga, N, O, and C are monitored. Immersion in a 4:1 solution of sulfuric acid (51%) to hydrogen peroxide (30%) followed by a 700 °C (200 °C below decomposition temperature) vacuum anneal (⩽10⁻¹⁰ Torr) results in a reduction of carbon and oxygen coverage to a few percent of a monolayer. This suggests a weakly bound oxide of carbon being chemisorbed to the GaN surface after the sulfuric acid/hydrogen peroxide treatment and it is removed by the heating. © 2002 American Vacuum Society.

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81.65.Cf	Surface cleaning, etching, patterning
73.20.At	Surface states, band structure, electron density of states
61.72.Cc	Kinetics of defect formation and annealing
68.43.Mn	Adsorption kinetics

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Neutral gas temperatures measured within a high-density, inductively coupled plasma abatement device

Eric J. Tonnis and David B. Graves

J. Vac. Sci. Technol. A 20, 1787 (2002); http://dx.doi.org/10.1116/1.1503901 (9 pages) | Cited 35 times

Online Publication Date: 5 September 2002

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The neutral temperature within a cylindrical, inductively coupled plasma source has been studied for rare gas and molecular plasmas using the technique of optical emission thermometry. By adding small quantities of N₂ to the gas feeds as an actinometer, the neutral temperature of the discharge can be estimated by simulation and fitting of the rotationally unresolved second positive band (C³Π_u–B³Π_g). In this work, the neutral temperature was estimated using this technique for flowing discharges of argon, helium, neon, nitrogen, and oxygen as a function of pressure and power. It was found that the neutral temperature for all of the discharges studied increased roughly proportional to the logarithm of the pressure. An increase in neutral temperature was also observed with increases in power; however, the dependence did not follow a simple functional form. The rare gases exhibited temperatures significantly above room temperature under high power (1200 W) and high pressure (∼1 Torr) conditions with argon approaching 2000 K. Molecular discharges such as N₂ and O₂ exhibited significantly higher temperatures (approaching 2500 K) than the rare gases even though they are expected to have lower plasma densities at the same pressure and power. It is believed that Franck–Condon heating of the gases during electron impact dissociation, vibrational excitation/thermalization, and exothermic wall reactions may all play important roles in producing such elevated temperatures. Simple, zero-dimensional plasma modeling indicates that neutral temperature elevation will result in significant increases in discharge electron temperature and electron-impact reaction rate coefficients under the same operating conditions. © 2002 American Vacuum Society.

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52.70.Kz	Optical (ultraviolet, visible, infrared) measurements
52.50.Dg	Plasma sources
34.80.Ht	Dissociation and dissociative attachment
52.40.Hf	Plasma-material interactions; boundary layer effects

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Epitaxial growth and dielectric properties of functionally graded (Ba_1−xSr_x)TiO₃ thin films with stoichimetric variation

Xinhua Zhu, Helen Lai-Wah Chan, Chung-Loong Choy, and Kin-hung Wong

J. Vac. Sci. Technol. A 20, 1796 (2002); http://dx.doi.org/10.1116/1.1503787 (6 pages) | Cited 11 times

Online Publication Date: 5 September 2002

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Functionally graded (Ba_1−xSr_x)TiO₃ (BST) thin films with stoichimetric variation (x:0.0–0.25) were layer-by-layer grown epitaxially on MgO (100) single-crystal substrates with 100-nm-thick conductive La_0.5Sr_0.5CoO₃ (LSCO) as the bottom electrode by pulsed-laser deposition. X-ray diffraction, rocking curve, and ϕ scans showed that the graded films are epitaxial grown with an orientation of [001](100)_BST//[001](100)_MgO. The surface roughness of the up-graded film was larger than that of the down-graded films, and the full width at half maximum of the BST (200) rocking curve of up-graded films was wider than that of the down-graded films. The compositional gradations along the depth in the films were confirmed by Rutherfold backscattering spectroscopy. Dielectric properties measured by vertical structures using LSCO as the bottom electrodes showed that the dielectric constant and dielectric loss at 10 kHz were 532 and 0.010 for the up-graded films, and 715 and 0.0103 for the down-graded films, respectively. An enhanced dielectric behavior was observed in the down-graded films. The graded BST films also exhibit a broad and flat profile of the dielectric constant versus the temperature. Such behavior of the dielectric response is attributed to the presence of the compositional and/or residual strain gradients in the epitaxial graded films. The possible origins of the enhanced dielectric behavior observed in the down-graded films are also briefly discussed. © 2002 American Vacuum Society.

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77.84.Ek	Niobates and tantalates
77.84.Cg	PZT ceramics and other titanates
77.55.-g	Dielectric thin films
68.55.-a	Thin film structure and morphology
77.22.Ch	Permittivity (dielectric function)
81.15.Fg	Pulsed laser ablation deposition
68.35.B-	Structure of clean surfaces (and surface reconstruction)
82.80.Yc	Rutherford backscattering (RBS), and other methods of chemical analysis
77.22.Gm	Dielectric loss and relaxation
68.60.Bs	Mechanical and acoustical properties

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Improvement of oxygen barrier of polyethylene terepthalate film by plasma-source ion implantation of carbon

M. Yoshida, T. Tanaka, M. Shinohara, S. Watanabe, J. W. Lee, and T. Takagi

J. Vac. Sci. Technol. A 20, 1802 (2002); http://dx.doi.org/10.1116/1.1503785 (6 pages) | Cited 9 times

Online Publication Date: 5 September 2002

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The surface of polyethylene terepthalate (PET) film has been successfully modified to amorphous carbon by plasma source ion implantation (PSII) as a means of improving the oxygen barrier characteristics of the PET film. The process was performed using high negative pulsed voltage in an radio frequency field with C₂H₂ gas. The amorphous carbon layer is found to consist primarily of graphite crystal with C–H, C–H₂ and C–H₃ components, and to reduce the oxygen transmission rate of the film by up to 100 times that of unmodified PET film at a thickness of only 70–300 nm. Raman spectra reveal that the amorphous carbon layer has diamond-like carbon characteristics, yet is soft compared to other diamond-like carbon films with hydrogen contents of >20 at. %. A stronger graphite character in the x-ray photoelectron spectroscopy spectra is found to represent the fineness of the carbon structure and correlate well with the improvement of oxygen barrier characteristics. © 2002 American Vacuum Society.

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81.65.-b	Surface treatments
61.80.Jh	Ion radiation effects
61.82.Pv	Polymers, organic compounds
68.35.B-	Structure of clean surfaces (and surface reconstruction)
78.30.-j	Infrared and Raman spectra
78.66.Qn	Polymers; organic compounds

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Angular dependence of SiO₂ etch rate at various bias voltages in a high density CHF₃ plasma

Gyeo-Re Lee, Sung-Wook Hwang, Jae-Ho Min, and Sang Heup Moon

J. Vac. Sci. Technol. A 20, 1808 (2002); http://dx.doi.org/10.1116/1.1503786 (7 pages) | Cited 10 times

Online Publication Date: 5 September 2002

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The dependence of the SiO₂ etch rate on the angle of ions incident on the substrate surface was studied over a bias voltage range from −20 to −600 V in a high-density CHF₃ plasma using a Faraday cage to control the ion incident angle. The effect of the bottom plane on the sidewall etching was also examined. Differences in the characteristics of the etch rate as a function of the ion angle were observed for different bias voltage regions. When the absolute value of the bias voltage was smaller than 200 V, the normalized etch rate (NER) defined as the etch rate normalized by the rate on the horizontal surface, changed following a cosine curve with respect to the ion incident angle, defined as the angle between the ion direction and the normal of the substrate surface. When the magnitude of the bias voltage was larger than 200 V, the NER was deviated to higher values from those given by a cosine curve at ion angles between 30° and 70°, and then drastically decreased at angles higher than 70° until a net deposition was observed at angles near 90°. The characteristic etch-rate patterns at ion angles below 70° were determined by the ion energy transferred to the surface, which affected the SiO₂ etch rate and, simultaneously, the rate of removal of a fluorocarbon polymer film formed on the substrate surface. At high ion angles, particles emitted from the bottom plane contributed to polymer formation on and affected the etching characteristics of the substrate. © 2002 American Vacuum Society.

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52.77.Bn

Etching and cleaning

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Thermal stability of arc evaporated high aluminum-content Ti_1−xAl_xN thin films

A. Hörling, L. Hultman, M. Odén, J. Sjölén, and L. Karlsson

J. Vac. Sci. Technol. A 20, 1815 (2002); http://dx.doi.org/10.1116/1.1503784 (9 pages) | Cited 70 times

Online Publication Date: 5 September 2002

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The thermal stability of Ti_1−xAl_xN films deposited by arc evaporation from Ti–Al cathodes with 67 and 75 at. % aluminum, respectively, has been investigated. The microstructure of as-deposited and isothermally annealed samples were studied using scanning electron microscopy, transmission electron microscopy, and x-ray diffraction. The chemical composition and elemental distribution were determined by energy dispersive x ray (EDX), Rutherford backscattering spectrometry, and EDX mapping. Transmission electron micrographs revealed a dense and columnar microstructure in the as-deposited condition. Films deposited from the 67 at. % cathodes were of cubic NaCl-structure phase, whereas films deposited from the 75 at. % cathodes exhibited nanocrystallites of wurzite-structure hexagonal-phase AlN in a cubic (c)-(Ti,Al)N matrix. Both films were stable during annealing at 900 °C/120 min with respect to phase composition and grain size. Annealing at 1100 °C of films deposited from the 67 at. % cathodes resulted in phase separation of c-TiN and h-AlN, via spinodal decomposition of c-TiN and c-AlN. (Ti,Al)N films undergo extensive stress relaxation and defect annihilation at relatively high temperatures, and aspects of these microstructural transformations are discussed. © 2002 American Vacuum Society.

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68.55.-a	Thin film structure and morphology
68.60.Dv	Thermal stability; thermal effects
81.15.Gh	Chemical vapor deposition (including plasma-enhanced CVD, MOCVD, ALD, etc.)
64.75.-g	Phase equilibria
52.77.Dq	Plasma-based ion implantation and deposition
68.37.Hk	Scanning electron microscopy (SEM) (including EBIC)
82.80.Yc	Rutherford backscattering (RBS), and other methods of chemical analysis
82.80.Ej	X-ray, Mössbauer, and other γ-ray spectroscopic analysis methods
61.46.-w	Structure of nanoscale materials
81.40.Gh	Other heat and thermomechanical treatments

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Multiple phase structures of Hf silicide precipitated from Hf silicate: An atomic view

Jung-Ho Lee and Masakazu Ichikawa

J. Vac. Sci. Technol. A 20, 1824 (2002); http://dx.doi.org/10.1116/1.1494814 (4 pages) | Cited 4 times

Online Publication Date: 5 September 2002

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Multiple phase structures of crystalline hafnium silicide precipitated from the silicate have been found as a function of temperature (900–1000 °C) by using scanning tunneling microscopy and x-ray photoelectron spectroscopy. At 900 °C, a crystalline silicate structure transforms into a bulklike (1×1) “facetbar” of HfSi₂ near the topmost surface, but into a “platelet” around the interface with Si. A Si-depletion zone is found to only form near platelets, not facetbars. Upon further annealing to 1000 °C, facetbars likely transform into platelets, and the atomic structure of a platelet also transforms to a patchlike feature having two equivalent antiphase sites, which are shifted by a half (∼2.3 Å) of the (1×1) unit length along the 〈110〉 directions. © 2002 American Vacuum Society.

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64.75.-g	Phase equilibria
81.30.Mh	Solid-phase precipitation
81.30.Dz	Phase diagrams of other materials
79.60.-i	Photoemission and photoelectron spectra
61.72.Mm	Grain and twin boundaries

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Plasma enhanced atomic layer deposition of SrTiO₃ thin films with Sr(tmhd)₂ and Ti(i-OPr)₄

J. H. Lee, Y. J. Cho, Y. S. Min, D. Kim, and S. W. Rhee

J. Vac. Sci. Technol. A 20, 1828 (2002); http://dx.doi.org/10.1116/1.1500745 (3 pages) | Cited 13 times

Online Publication Date: 5 September 2002

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SrTiO₃ (STO) thin films were deposited in the deposition temperature range of 250–350 °C by plasma enhanced atomic layer deposition (PEALD) with Sr(tmhd)₂ (tmhd=tetramethyl heptanedionate) and Ti(i-OPr)₄ (i-OPr=iso-propoxide) as a precursor. Two precursors were dissolved in tetrahydrofuran, delivered into the vaporizer separately by a newly developed pulse injection method, and the vapor mixture was introduced into the reactor. An argon purge was inserted after the precursor injection and afterward, plasma was generated with the oxygen introduction. Deposition rate was saturated at 0.3–0.4 Å/cycle. Despite the poor volatility of Sr(tmhd)₂, SrTiO₃ thin films were reproducibly deposited and using plasma activated O₂ gas as an oxidant, films could be deposited at low temperature with carbon residue of STO thin films minimized. Step coverage of both SrO and SrTiO₃ were above 90% due to the self-limiting growth behavior of atomic layer deposition process. © 2002 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
77.84.Ek	Niobates and tantalates
77.84.Cg	PZT ceramics and other titanates
82.33.Ya	Chemistry of MOCVD and other vapor deposition methods
68.55.A-	Nucleation and growth

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Sep 2002

Volume 20, Issue 5, pp. 1511-1830

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