By Topic

Journal of Vacuum Science & Technology A: Vacuum, Surfaces, and Films

Issue 1 • Date Jan 1999

Filter Results

Displaying Results 1 - 25 of 54
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (37 KB)  
    Freely Available from IEEE
  • Homoepitaxial growth of CdTe on vicinal CdTe(100) surfaces: Reaction kinetics and mechanism

    Page(s): 1 - 8
    Save to Project icon | PDF file iconPDF (301 KB)  

    Homoepitaxial films of CdTe were grown on vicinal CdTe(100) surfaces using Cd(CH3)2 and Te(C3H7)2 precursors in an atmosphere of H2. The vicinal CdTe(100) substrates were misoriented by 0°, 2°, 4°, 6°, and 8° from the (100) direction towards the (111)Te direction and thus had systematically increasing step densities. The CdTe films grown on these surfaces were single crystalline and epitaxial but had gross surface morphologies that depended on the misorientation of the substrate. Films grown on the CdTe(100)-0° and CdTe(100)-8° substrates were rough while those grown on the CdTe(100)-4° substrate were smooth. The kinetics of film growth were studied through measurements of the overall film growth rates and measurements of precursor adsorption/desorption kinetics. Film growth rates were weakly dependent on the degree of substrate misorientation, increasing slightly with increasing step density. Although the step density determines film morphology, the steps are not active sites for decomposition of precursors and do not participate in the rate determining steps of the growth mechanism. Studies of the surface chemistry of the Cd(CH3)2 and Te(C3H7)2 precursors show that they are reversibly adsorbed on the vicinal CdTe(100) surfaces, which is quite different from precursor surface chemistry on III–V semiconductors where adsorption tend- - s to be irreversible. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Molecular beam epitaxial growth and structural properties of Bi1-xSbx alloy thin films on CdTe(111) substrates

    Page(s): 9 - 13
    Save to Project icon | PDF file iconPDF (316 KB)  

    We have successfully grown BiSb alloy thin films on CdTe(111)B over a wide range of Sb compositions using molecular beam epitaxy. Structural properties have been investigated using in situ reflection high-energy electron diffraction, x-ray diffraction, and atomic force microscopy. Adding Sb to Bi leads to a reduction of the lattice constant, poorer crystallinity, and a rougher surface morphology. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Room-temperature growth of ZrO2 thin films using a novel hyperthermal oxygen-atom source

    Page(s): 14 - 18
    Save to Project icon | PDF file iconPDF (196 KB)  

    Thin ZrO2 films have been grown on Si(100) and on glassy carbon substrates using a novel atomic oxygen source in a standard molecular beam epitaxy system. The oxygen source produces a flux of hyperthermal oxygen atoms with an ion/atom-ratio ≪0.001 through electron stimulated desorption from a Ag alloy surface at an operating pressure ≪10-8 Torr. The films were grown at room temperature and analyzed using Rutherford backscattering spectroscopy, x-ray diffraction (XRD), x-ray photoelectron spectroscopy and transmission electron microscopy (TEM). The results show the successful growth of fully stoichiometric ZrO2 films on nonheated Si(100) and on amorphous glassy carbon substrates at a rate of 0.58 μm/hr. The XRD and TEM investigations indicate the formation of a mixed amorphous/orthorhombic film structure. Based on the film growth rate, the O flux produced by the electron stimulated desorption atom source is estimated to be 8×1014 atoms/cm2s. This flux value is consistent with other determinations using ion scattering spectroscopy and pyromellitic dianhydride-oxydianiline polyimide (Kapton®) erosion experiments. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Low energy ion beam etching of CuInSe2 surfaces

    Page(s): 19 - 25
    Save to Project icon | PDF file iconPDF (313 KB)  

    A nitrogen ion beam was used to etch the surface of CuInSe2 single crystals. This technique, applied to CuInSe2 for the first time, was studied with respect to surface damage production at various ion energies and was compared to commonly used argon ion sputtering. Raman scattering and atomic force microscopy were applied as characterization methods. We observed a stress induced redshift of the Raman mode for the argon etched samples which could be explained by tensile stress in the damaged layer. Nitrogen ion beam etching at an energy of 1000 eV causes a blue shift due to the increased lattice damage. Nitrogen ion beam etching at energies below 500 eV was found to produce the lowest degree of damage and the lowest surface roughness, as compared with mechanical polish or argon ion sputtering. Therefore, this method is suitable for dry etching and smoothing of CuInSe2. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Study of the SiO2-to-Si3N4 etch selectivity mechanism in inductively coupled fluorocarbon plasmas and a comparison with the SiO2-to-Si mechanism

    Page(s): 26 - 37
    Save to Project icon | PDF file iconPDF (485 KB)  

    The mechanisms underlying selective etching of a SiO2 layer over a Si or Si3N4 underlayer, a process of vital importance to modern integrated circuit fabrication technology, has been studied. Selective etching of SiO2-to-Si3N4 in various inductively coupled fluorocarbon plasmas (CHF3, C2F6/C3F6, and C3F6/H2) was performed, and the results compared to selective SiO2-to-Si etching. A fluorocarbon film is present on the surfaces of all investigated substrate materials during steady state etching conditions. A general trend is that the substrate etch rate is inversely proportional to the thickness of this fluorocarbon film. Oxide substrates are covered with a thin fluorocarbon film (≪1.5 nm) during steady-state etching and at sufficiently high self-bias voltages, the oxide etch rates are found to be roughly independent of the feedgas chemistry. The fluorocarbon film thicknesses on silicon, on the other hand, are strongly dependent on the feedgas chemistry and range from ∼2 to ∼7 nm in the investigated process regime. The fluorocarbon film thickness on nitride is found to be intermediate between the oxide and silicon cas- - es. The fluorocarbon film thicknesses on nitride range from ∼1 to ∼4 nm and the etch rates appear to be dependent on the feedgas chemistry only for specific conditions. The differences in etching behavior of SiO2, Si3N4, and Si are suggested to be related to a substrate-specific ability to consume carbon during etching reactions. Carbon consumption affects the balance between fluorocarbon deposition and fluorocarbon etching, which controls the fluorocarbon steady-state thickness and ultimately the substrate etching. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Characterization of Cl2/Ar high density plasmas for semiconductor etching

    Page(s): 38 - 51
    Save to Project icon | PDF file iconPDF (12274 KB)  

    Chlorine-based high density plasmas, commonly used in the etching of elemental and compound semiconductors, are characterized using mass spectrometry, optical emission spectroscopy, and electrostatic probes. Plasma fluxes are characterized by three-dimensional Langmuir probe measurements and optical emission spectroscopy. The flux is further characterized at the substrate platen by mass spectrometry to determine its makeup in terms of charged or neutral species and atomic or molecular species. Langmuir probe investigations show variations in electron temperature (2–6 eV), plasma density (1×1010 to 1×1012cm-3), and plasma potential (5–25 V) as process conditions (microwave power, total pressure, and fraction of Cl2 in Ar) and measurement location are varied. Concurrent optical emission spectroscopy measurements of ionized species are in general agreement with Langmuir probe results. Further, optical emission spectroscopy of neutral and ionized species provides global insight into the variation of atomic/molecular fractions in the plasma as it is transported to the substrate processing region. At the substrate, mass spectrometric characterizations show Cl+ and Ar+ dominating the flux for low pressure and high powers, while Cl2 and Ar dominate at high pressure and low power. For Cl2 fractions greater than 25% molecular chlorine begins to dominate the flux to the substrate. These observations of processing space are discussed with respect to implications on semiconductor etching and regions most suitable to high rate, anisotropic processing- - conditions are identified. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Response surface study of inductively coupled plasma etching of GaAs/AlGaAs in BCl3/Cl2

    Page(s): 52 - 55
    Save to Project icon | PDF file iconPDF (309 KB)  

    A central composite design response surface study was used to determine the etching characteristics of GaAs/AlGaAs in high-density inductively coupled BCl3/Cl2-based plasmas as a function of process parameters including inductive power, substrate bias, and pressure. Equietch rates were obtained for GaAs and AlxGa1-xAs in the entire parameter space investigated and ranged from approximately 0.3 to 1.0 μm/min. The etch rate of GaAs/AlGaAs grew with an increase in all three parameters. Variations in inductive power had the maximum effect on the etch rate while the bias affected the etch rate the least. In contrast, bias played a significant role in the etch rate of photoresist indicating different mechanisms for resist etching. An ion energy threshold was observed for resist etching which was found to increase with decreasing inductive power. Anisotropic GaAs/AlGaAs etch profiles were obtained over a wide range of parameters including very low substrate bias. Extremely smooth etched surfaces were observed for most etch conditions. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Reactive ion etching of GaN and GaAs: Radially uniform processes for rectangular, smooth sidewalls

    Page(s): 56 - 61
    Save to Project icon | PDF file iconPDF (277 KB)  

    Vertical and smooth cutting of GaN has been demonstrated applying reactive ion etching (RIE) in capacitively coupled plasmas using parallel-plate reactors (common RIE) and in plasmas driven by electron cyclotron resonance (ECR). The radial uniformity across 50 mm (2 in.) is no issue in ECR-driven plasmas and can be effectively improved in parallel-plate reactors by using shower heads with one central hole only, provided the wafer is centrally placed. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Penning type magnetron sputtering source and its use in the production of carbon nitride coatings

    Page(s): 62 - 69
    Save to Project icon | PDF file iconPDF (2784 KB)  

    This article describes the design and construction of a Penning type sputter magnetron which is referred to as the Dimag source. This device is capable of producing intense discharges at pressures well below those obtainable using a conventional magnetron source. Expressions used to describe the associated magnetic field are highlighted. An account of the effective potential well as seen by charged species within the plasma is given. Various operational parameters are described. The device is used to produce carbon nitride coatings with high atomic percent nitrogen incorporation. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Abnormal steady states in reactive sputtering

    Page(s): 70 - 76
    Save to Project icon | PDF file iconPDF (123 KB)  

    For a sputter system equipped with a constant current power supply and under reactive gas flow control, certain compositions of film are usually not accessible in the normal steady states because of the transition of steady state and the hysteresis effect. Theoretical studies in this article indicated that there exist abnormal steady states where films of intermediate compound contents may possibly be produced. However, the experimental endeavors to attain these states in a system under current/flow control failed. Further theoretical studies in this work indicated that not only are the abnormal steady states difficult to establish, but also they are sensitive to tiny drifts in parameter. In other words, in a sputter system with constant discharge current and constant reactive gas flow, the abnormal steady states can only be achieved and maintained when the parameters are set and kept in point sharply. These theoretical results revealed why it is not practically possible to operate steadily between the metal sputtering region and the compound sputtering region when a sputter system is under flow/current control. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hollow cathode magnetron

    Page(s): 77 - 82
    Save to Project icon | PDF file iconPDF (132 KB)  

    A new type of plasma sputtering device, named the hollow cathode magnetron (HCM), has been developed by surrounding a planar magnetron cathode with a hollow cathode structure. Operating characteristics of HCMs, current–voltage (I–V) curves for fixed discharge pressure and voltage–pressure (V–p) curves for fixed cathode current, are measured. Such characteristics are compared with their planar magnetron counterparts. New operation regimes, such as substantially lower pressures (0.3 mTorr), were discovered for HCMs. Cathode erosion profiles show marked improvement over planar magnetron in terms of material utilization. The use of HCMs for thin film deposition are discussed. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ferroelectric SrBi2Ta2O9 thin film deposition at 550 °C by plasma-enhanced metalorganic chemical vapor deposition onto a metalorganic chemical vapor deposition platinum bottom electrode

    Page(s): 83 - 87
    Save to Project icon | PDF file iconPDF (286 KB)  

    Ferroelectric bismuth-layer SrBi2Ta2O9 (SBT) thin films were prepared on Pt/SiO2/Si substrates by plasma-enhanced metalorganic chemical vapor deposition. The platinum bottom electrode deposited by metalorganic chemical vapor deposition shows a dense smooth state after deposition of SBT films and prevents bismuth diffusion into the platinum layer. The c-axis oriented SBT films were crystallized at a deposition temperature of 550 °C. The dielectric constant and dissipation factor of SBT films are 310 and 0.08, respectively, at 100 kHz. The remanent polarization and the coercive field obtained for 180 nm thick Sr0.9Bi2Ta2O9 films deposited at 550 °C were 15 μ/cm2 and 50 kV/cm, respectively, at an applied voltage of 5 V. The leakage current density was about 5.0×10-7 A/cm2 at 250 kV/cm. The films showed fatigue-free characteristics up to 7.0×109 switching bipolar pulses under 5 V.© 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effect of prepared GaAs surface on the sulfidation with (NH4)2Sx solution

    Page(s): 88 - 92
    Save to Project icon | PDF file iconPDF (105 KB)  

    Surface properties of wet-cleaned or successively passivated GaAs with (NH4)2Sx solution were analyzed using x-ray photoelectron spectroscopy. All the treatments were carried out in a glove box under nitrogen controlled atmosphere. Every cleaning process with HCl or H3PO4 solution produced elemental As and the amount depends on the etching capability of acid to GaAs. Successive sulfidation treatment resulted in the formation of an As–S bond, and the observed quantity of the arsenic sulfide was closely related to the amount of elemental As. In particular, the As–S was hardly observed in the sulfidation treated GaAs surface after NH4OH treatment because elemental As had not been produced by the NH4OH treatment. The in situ annealed GaAs surface at 600 °C contained a large amount of elemental Ga and showed an effective formation of Ga–S after the sulfidation treatment. Therefore, it could be assured that the elemental forms of As and Ga bind with S through the sulfidation treatment using a (NH4)2Sx solution. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Surface roughness and oxide contents of gas-phase and solution-phase polysulfide passivation of III–V surfaces

    Page(s): 93 - 96
    Save to Project icon | PDF file iconPDF (62 KB)  

    A surface etching effect was observed using polysulfide solution for the passivation of III–V semiconductors. The etching rate was found to be 2 Å/min on InP (100). The etching effect increased surface roughness, which enhanced the adsorption of adventitious hydrocarbons and water from the ambient. Such an etching effect was not observed on the samples treated by a gas-phase polysulfide treatment. The surfaces of these samples also showed less adventitious hydrocarbons and water after exposure to the ambient. The presence of sulfide on the surface reduced the sticking coefficient of the adventitious hydrocarbons and water. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Passivation of CdZnTe surfaces by oxidation in low energy atomic oxygen

    Page(s): 97 - 101
    Save to Project icon | PDF file iconPDF (210 KB)  

    A method of surface passivation of Cd1-xZnxTe (CZT) x-ray and gamma ray detectors has been established by using microwave-assisted atomic oxygen bombardment. Detector performance is significantly enhanced due to the reduction of surface leakage current. CZT samples were exposed to an atomic oxygen environment at the University of Alabama in Huntsville’s Thermal Atomic Oxygen Facility. This system generates neutral atomic oxygen species with kinetic energies of 0.1–0.2 eV. The surface chemical composition and its morphology modification due to atomic oxygen exposure were studied by x-ray photoelectron spectroscopy and atomic force microscopy and the results were correlated with current-voltage measurements and with room temperature spectral responses to 133Ba and 241Am radiation. A reduction of leakage current by about a factor of 2 is reported, together with significant improvement in the gamma-ray line resolution. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Deposition of high quality silicon dioxide on Hg1-xCdxTe by low-temperature liquid phase deposition method

    Page(s): 102 - 107
    Save to Project icon | PDF file iconPDF (122 KB)  

    A low temperature (35–45 °C) process of liquid phase deposition (LPD) for the growth of silicon dioxide (SiO2) on Hg1-xCdxTe is proposed. To enhance the formation of SiO2, the HgCdTe surface has to be treated by ammonia solution before LPD. A thin native oxide which is formed by previous surface treatment involving OH- radicals greatly enhances the SiO2 deposition on HgCdTe. Thus, SiO2 films with a high refractive index (1.465) and a low p-etching rate (34 Å/s) were obtained. Auger electron spectroscopy depth profile shows less interdiffusion of constituent atoms between the SiO2 layer and the HgCdTe substrate. Electrical properties of the SiO2/p-HgCdTe interface are also characterized at 77 K. It is found that the p-HgCdTe surface is accumulated and the effective surface charge density is estimated to be -2.25×1010 cm-2. The leakage current and dielectric breakdown strength are also found to be 0.356 nA (at -5 V) and above 650 KV/cm, respectively. Furthermore, the growth mechanism of LPD-SiO2 on HgCdTe is proposed. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hydrogenated silicon nitride thin films deposited between 50 and 250 °C using nitrogen/silane mixtures with helium dilution

    Page(s): 108 - 112
    Save to Project icon | PDF file iconPDF (94 KB)  

    Silicon nitride thin films, deposited by plasma enhanced chemical vapor deposition at temperatures between 250 and 50 °C from SiH4, N2 and He, were characterized using transmission infrared spectroscopy, ellipsometry, wet etch rate, and current-voltage analysis. At 250 °C using SiH4/N2/He flow ratios of 1/150/75, films with refractive index=1.80 and H concentrations ≪20%, distributed equally in Si-H and N-H units were obtained. The concentration of hydrogen and its distribution in N-H and Si-H bonds are sensitive to process temperature, suggesting that thermally driven N incorporation reactions are important during growth. Inert gas dilution allows films to be formed at ≪100 °C, with bonded hydrogen configurations similar to films deposited at higher temperatures. Current versus voltage traces of as-deposited films show charge trapping, which can be reduced by extended low temperature anneals. These results show that chemical composition can be controlled in low temperature silicon nitride deposition. This processing approach may be useful for encapsulation or for barrier layer formation on low temperature organic electronic devices or flexible transparent plastic substrates. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Deposition of ultrapure hydrogenated amorphous silicon

    Page(s): 113 - 120
    Save to Project icon | PDF file iconPDF (594 KB)  

    We have succeeded in a drastic reduction of impurity contents in hydrogenated amorphous silicon (a-Si:H) films by a newly developed ultrahigh vacuum plasma-enhanced chemical vapor deposition (UHV/PECVD) system. High sensitivity secondary ion mass spectrometry shows that impurity contents in the films are as low as 1015 cm-3 both for oxygen and carbon, and 1014 cm-3 for nitrogen. These values represent the lowest concentrations of atmospheric contaminants for a-Si:H films reported so far. In particular, oxygen content has not been reduced below 1×1018 cm-3 using conventional UHV/PECVD techniques, and not below 5×1017 cm-3 even by high growth rate process of very high frequency plasma. The essential features of the present UHV/PECVD system are an extremely low outgassing rate of 8×10-9 Torr l/s, extremely low partial pressure of contaminant gas species ≪10-12 Torr, and purification of feed gas SiH4 at “point of use.” The specific origins of impurities in the films are discussed: outgassing of the reactor wall, the purity of feed gas, and the plasma-wall interaction process. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Deposition of diamond-like carbon films using the screen grid method in electron cyclotron resonance chemical vapor deposition

    Page(s): 121 - 124
    Save to Project icon | PDF file iconPDF (61 KB)  

    The deposition of diamond-like carbon (DLC) films from a mixture of hydrogen and methane using the electron cyclotron resonance chemical vapor deposition method is reported. A new technique based on a dc bias applied to a two-tier screen grid positioned above the substrate has been used to provide an electric field to accelerate the ions towards the substrate during deposition. The structural characteristics of the DLC films have been studied using Raman spectroscopy. Under conditions of 400 W microwave power and 6.5 mTorr process pressure, films deposited using the screen grid method were found to be hard and diamond-like and to contain a low bonded hydrogen content, as opposed to films deposited conventionally with dc bias applied directly to the substrate holder. The results showed that the dc bias applied to the lower grid of the screen grid fixture has the effect of accelerating the ionic species to impinge onto the substrate, hence promoting DLC film growth. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Diagnostics and modeling in a pure argon plasma: Energy balance study

    Page(s): 125 - 132
    Save to Project icon | PDF file iconPDF (170 KB)  

    A self-consistent pseudo-one-dimensional (zero-dimensional with diffusion) plasma model and optical emission spectroscopy are used in tandem to investigate the power coupling efficiency for a pure argon microwave plasma. The self-consistent model is developed by simultaneously solving the Boltzmann equation (for the non-Maxwellian electron energy distribution function), electron number density balance equation, energy balance equation, and the excited state rate equations in a collisional-radiative model. The absolute line emission intensity is utilized to obtain number densities of three argon excited states [4p (7147 Å), 5p (4300 Å), and 5d (6043 Å)] in a 5 Torr, 680 W input power argon discharge. The absolute continuum emission from the plasma was utilized to determine the maximum electron number density. A comparison of the numerical and experimental data indicates that only 2%–5% (10–35 W) of the input power is deposited in the plasma. A control volume heat transfer analysis validates this claim. The experimentally determined energy balance shows that the remaining input power (645–670 W) bypasses the plasma and is dissipated in the reactor cooling systems. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High temperature oxidation of (Ti1-XAlX)N coatings made by plasma enhanced chemical vapor deposition

    Page(s): 133 - 137
    Save to Project icon | PDF file iconPDF (250 KB)  

    (Ti1-XAlX)N coatings were deposited by the plasma enhanced chemical vapor deposition method using a gas mixture of TiCl4, AlCl3, NH3, H2 and Ar, and the oxidation behavior at high temperatures as well as the oxidized structure of the coatings were examined. The oxidation rate of the coatings at temperatures below 1000 °C was found to fit well to a parabolic time dependence. It has also been found that up to 900 °C (Ti1-XAlX)N coatings at X≥0.25 showed considerably improved oxidation resistance compared to TiN, due to the formation of a dense α-Al2O3 layer at the surface of the coatings. At X≪0.25, however, this dense protective layer could not form, and the coatings were fully oxidized after a short period of time. When the temperature reached 900 °C, Fe in the substrate diffused out through the coating by pipe diffusion as well as through the cracks that were produced by thermal stresses, and oxidized rapidly at the surface of the coating.© 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Diagnostics of the diamond depositing inductively coupled plasma by electrostatic probes and optical emission spectroscopy

    Page(s): 138 - 143
    Save to Project icon | PDF file iconPDF (125 KB)  

    Electrostatic probe methods and optical emission spectroscopy have been used for diagnostics of the low-pressure inductively coupled radio frequency plasma at pressures between 5 and 80 mTorr under real environments of diamond deposition. The single, triple, and emissive probe methods were used alone or combined to obtain electron temperature (Te) and electron density (ne). The single or triple probe method combined with the emissive probe method allowed the determination of ne with high reliability as confirmed by cross-checking. Comparison with the grown deposits suggested the existence of a critical ne value of around 2×1010cm-3, which was responsible for the drastic decrease in diamond growth rate observed below 10 mTorr and the resulting no growth at around 5 mTorr. The energy distribution of excitation levels of the H atom Balmer series was almost constant and the distribution equilibrium was not established except the case of 5 mTorr, which was ascribed to the difference in the excitation process of H atoms. © 1999 American Vacuum Society.   View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Kinetics of platinum silicide formation followed in situ by spectroscopic ellipsometry

    Page(s): 144 - 149
    Save to Project icon | PDF file iconPDF (127 KB)  

    In situ ellipsometry is employed to study the kinetics of Pt silicide formation by thermal annealing with constant heating rates up to 30 K/min of a 10 nm platinum layer on silicon (100). From spectroscopic ellipsometry data of the initial Pt/Si, the intermediate Pt2Si, and the final PtSi phase an optimum photon energy of 3.5 eV was chosen for the kinetic study. Characteristic changes of the ellipsometric angles are observed as a function of temperature when the reaction fronts reach a depth below the surface that is related to the absorption length of the 3.5 eV photons. From an analysis of these transition temperatures based on the Kissinger formalism the activation energies for the formation of Pt2Si and PtSi are obtained as 1.55±0.05 and 1.72±0.05 eV, respectively, where the error bars follow from the precision of our measurements. A comparative study for a 100 nm Pt layer on Si yields the same activation energies albeit with a higher uncertainty, indicating that this method is particularly suited for ultrathin silicides. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Ultraviolet-ozone jet cleaning process of organic surface contamination layers

    Page(s): 150 - 154
    Save to Project icon | PDF file iconPDF (110 KB)  

    To understand the ultraviolet (UV)-ozone jet cleaning process of organic surface contamination layers, adventitious hydrocarbon layers on Si, self-assembled octadecyltrichlorosilane monolayers on Si, and self-assembled C60H–(CH2)12–SH monolayers on Au were cleaned with pure ozone jet and UV irradiation. Cleaned surfaces were analyzed with in situ x-ray photoelectron spectroscopy measurements. Ozone molecules could react with the unsaturated C–C bonds in self-assembled C60H–(CH2)12–SH monolayers on Au surfaces at room temperature. However, the saturated C–C bonds in OTS hydrocarbon molecules adsorbed on Au surfaces reacted not with ozone molecules but with oxygen radicals generated by the dissociation of ozone molecules under UV irradiation. For adventitious carbon contamination on Si surfaces, only a fraction could be cleaned by ozone at room temperature but it could be almost cleaned with UV-ozone jet. © 1999 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.

Aims & Scope

The Journal of Vacuum Science and Technology A is devoted to reports of original research, review articles, and Critical Review articles.

Full Aims & Scope

Meet Our Editors

Editor
G. Lucovsky
North Carolina State University