By Topic

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

Issue 2 • Date Mar 1998

Filter Results

Displaying Results 1 - 25 of 92
  • Issue Table of Contents

    Page(s): toc1
    Save to Project icon | PDF file iconPDF (57 KB)  
    Freely Available from IEEE
  • X-ray photoelectron spectroscopy of air-exposed C60 films: Origin of the O1s core peak

    Page(s): 385 - 388
    Save to Project icon | PDF file iconPDF (68 KB)  

    X-ray photoelectron spectra of C60 films exposed to air of ca. 20% and 60% humidity at 23 °C for 1 h are presented. It was found that the O1s core peak appeared at a binding energy of 533.5 eV for the film exposed to air of ca. 60% humidity, while no peak corresponding to the O1s photoelectrons was observed for the film exposed to air of ca. 20% humidity. The binding energy of 533.5 eV for the O1s core peak is close to that of about 533 eV for the O1s core peak of solid H2O, while it is different from that of 537 eV for the O1s core peak of solid O2 on C60 film. These facts indicate that the O1s peak observed for the air-exposed C60 film was due to H2O molecules adsorbed on the film. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Structural transition of Fe and Co sublayers in Fe/Zr and Co/Zr multilayered films investigated by magneto-optical spectroscopy

    Page(s): 389 - 392
    Save to Project icon | PDF file iconPDF (74 KB)  

    The experimental and computer-simulation study of the magneto-optical properties (equatorial Kerr effect) of Fe/Zr and Co/Zr multilayered films was carried out. Drastic changes in the magneto-optical properties of the Fe/Zr and Co/Zr multilayered films were observed with the ferromagnetic sublayers that had less than the critical thickness. Such a behavior is connected with a polycrystalline–amorphous transformation in these sublayers. An annealing of the multilayered film led to a significant increase in the equatorial Kerr effect value which is caused by a partial crystallization of the amorphous Fe or Co sublayers. The real interface structures of the Fe/Zr and Co/Zr multilayered films were estimated by a fitting procedure between the experimental and the computer-simulated equatorial Kerr effect spectra of the multilayered films. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • X-ray photoelectron spectroscopy valence band data for ZnS, SrS, and Sr0.45Ca0.55Ga2S4 luminescent thin films

    Page(s): 393 - 396
    Save to Project icon | PDF file iconPDF (74 KB)  

    The valence band of ZnS, SrS, and Sr0.45Ca0.55Ga2S4 thin film phosphors were measured by x-ray photoelectron spectroscopy. The valence band spectrum from polycrystalline ZnS film compared favorably with that previously reported for ZnS single crystals, and with calculated theoretical densities of states (after convolution with a Gaussian curve). The SrS valence band spectrum exhibited three peaks, which generally agree with the expected densities of states. The Sr0.45Ca0.55Ga2S4 spectrum features were much less intense, consistent with the film being amorphous. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Excited state density distributions of H, C, C2, and CH by spatially resolved optical emission in a diamond depositing dc-arcjet reactor

    Page(s): 397 - 408
    Save to Project icon | PDF file iconPDF (240 KB)  

    Spatially resolved optical emission spectroscopy is used to investigate excited species in a dc-arcjet diamond depositing reactor. Temperature measurements indicate a cold plasma with electrons, excited states, and gas in nonthermal equilibrium. The H, C, C2, and CH excited state number densities decrease exponentially with the distance from the nozzle and have a pronounced increase in the shock structure above the substrate. The H emission increases throughout the boundary layer to the substrate surface, whereas emission from other species has a maximum in the boundary layer and then decreases again towards the substrate. The reconstructed radial distribution of excited state concentrations are Gaussian, with the C and C2 distributions broader than the H and CH ones. The optical emission is calibrated with either Rayleigh scattering or laser-induced fluorescence to furnish absolute number densities. We find all the excited species to be present in concentrations two or more orders of magnitude smaller than the corresponding ground states measured in the same reactor and conditions. We find that C2(d-a) emission intensity correlates well with laser-induced fluorescence measurements of C2(a) concentration in the arcjet plume. Ground state concentrations of the other species do not vary as their emission intensity except near the substrate, where the variations of CH(A-X), CH(B-X), and C2(d-a) emission intensities are good monitors of the corresponding concentration changes. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Accurate determination of the optical constants of sputter-deposited Ag and SnO2 for low emissivity coatings

    Page(s): 409 - 412
    Save to Project icon | PDF file iconPDF (79 KB)  

    The determination of the values of the optical constants (n, refractive index and k, extinction coefficient) in the visible range (400–700 nm approximately) of both silver (Ag) and tin oxide (SnO2) films is a necessary condition to predict the behavior of a SnO2/Ag/SnO2 multilayer low emissivity coating in relation to visual comfort. For this purpose, thin films of Ag and SnO2 with a thickness similar to that in multilayer coatings (90 and 380 Å, respectively) were used in order to avoid the thickness dependence of the optical constants. A simulation computational program based on the matrix method was employed to determine the values of the optical constants of these films in the visible range. It has been demonstrated that for the design of optical coatings with optimal properties it is essential a great accuracy in the determination of the optical constants, since a minimum variation of these values leads to a deterioration of the behavior of the whole coating. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High resolution Auger electron spectroscopy studies on (100) and (111) facets of chemical vapor deposited diamond

    Page(s): 413 - 418
    Save to Project icon | PDF file iconPDF (288 KB)  

    Diamond thin films were grown by microwave plasma and hot filament chemical vapor deposition (MPCVD and HFCVD, respectively) techniques. Films were systematically characterized by x-ray diffraction, micro-Raman spectroscopy, scanning electron microscopy (SEM), and Auger electron spectroscopy (AES). Although the results obtained using various characterization techniques are broadly similar, there are however subtle differences. For instance, Raman spectra show a sharp peak at 1332 cm-1 corresponding to natural diamond in both types of films. The intensity and the position of the non-diamond band in the two sets of films differ. While the maxima of the non-diamond band in HFCVD film lies at 1450 cm-1, in MPCVD film it occurs at 1525 cm-1. Also the values of FWHM in HFCVD film (≃ 7.5 cm-1) are smaller than the MPCVD films (≃ 9.5 cm-1). This may indicate that the concentration of non-diamond carbon impurities on the grain boundaries of HFCVD films are really small. SEM results on the other hand indicate that the grain size of the MPCVD films is larger than HFCVD films. AES was performed in a survey scan (beam size ∼10 μm × 8 μm) and high resolution (beam size  0.2 μm) mode with an initial aim to investigate the surface characteristics and environment of carbon atoms of the diamond films. In the survey scan, the spectra show a line shape typical of CVD diamond films. Anomalous results were obtained when the AES was performed on (100) and (111) facets in high resolution mode. This may be explained in terms of the surface reconstruction taking place due to hydrogen desorption via core-hole Auger decay process. Auger depth profiles were- - also obtained on the facets which reveal that Si, O, and N are the dominant impurities. The impurity content of HFCVD films is observed to be lower by a factor of 2 as compared to MPCVD films. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Fourier transform infrared diagnostics of gas phase reactions in the metalorganic chemical vapor deposition of aluminum from dimethylethylamine alane

    Page(s): 419 - 423
    Save to Project icon | PDF file iconPDF (98 KB)  

    The gas phase reaction mechanism in the aluminum metalorganic chemical vapor deposition from dimethylethylamine alane (DMEAA) was investigated by Fourier transform infrared spectroscopy. DMEAA in the gas phase was dissociated into dimethylethylamine and alane even at room temperature and the dissociation rate was accelerated at higher gas temperatures. Alane, produced from the dissociation of DMEAA, disappeared rapidly and the intermediates, produced during the degradation of alane, may form Al particles. The dissociation reaction was found to be a first order reaction, and the activation energy was about 9.56 kcal/mol. In H2 carrier gas, the dissociation of DMEAA was slower than that in Ar gas. The deposition rate was decreased when the substrate temperature was above 150 °C because DMEAA decomposed rapidly in the gas phase. From the experimental observations, a gas phase reaction mechanism was proposed and the degradation mechanism of liquid DMEAA was suggested. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Antireflective coating on TeO2 crystal for the high power acousto-optic modulator

    Page(s): 424 - 428
    Save to Project icon | PDF file iconPDF (591 KB)  

    The purpose of this research is to develop broadband antireflection (A/R) coating for a high power acousto-optic modulator with the following specifications: the substrate material is TeO2 and the requirement of T (transmittance) for both sides greater than 98% in the spectral region 410–700 nm with laser power damage threshold is greater than 40 W/mm2. The technology of A/R coating is based on the conventional method of nonreactive evaporation from electron beam gun sources oxides of Zr (ZrO2 films as a layer with high refractive index) and Si (SiO2 films as a layer with low refractive index), and YF3 (yttrium fluoride) films on TeO2 crystals substrate with pre-cleaning by using an ion beam gun (Refs. and ). The refractive indices of the mentioned films are: n(ZrO2)=1.96–1.98, n(SiO2)=1.45–1.46, and n(YF3)=1.48–1.50 (Ref. ). In all cases properties of A/R coating are strongly dependent on the method of surface cleaning, type of polishing, and even the bulk properties of the substrate. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Studies of metallic multilayer structures, optical properties, and oxidation using in situ spectroscopic ellipsometry

    Page(s): 429 - 435
    Save to Project icon | PDF file iconPDF (155 KB)  

    In situ spectroscopic ellipsometry (SE) has been successfully used to accurately measure sputter deposition rates and optical constants of un-oxidized metal layers and to control the growth of magnetic multilayers. The structures include [Co/Cu]n, [Co/Au]n, [Co/Ni]n, [Co/Pd]n and [Co/Pd/Au]n. Layer thickness precision is better than ±0.05 nm for layer thicknesses in the range of 0.2 nm to 10 nm. Closed-loop feedback control of layer thickness is also demonstrated. Good consistency was obtained by comparing the in situ SE results to x-ray diffraction measurements. Dynamic oxidation studies of [Co/Au]n and [Co/Ni]n multilayer structures are also presented. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optical and transport properties of amorphous and microcrystalline silicon films prepared by excimer laser assisted rf glow-discharge deposition

    Page(s): 436 - 443
    Save to Project icon | PDF file iconPDF (489 KB)  

    Hydrogenated amorphous and microcrystalline silicon films were deposited on glass substrates at 250 °C by combining rf glow discharge decomposition of silane–helium gas mixtures and ultraviolet laser irradiation on the surface of the growing film. The effect of the laser fluence on the optical and electrical properties of the films was investigated with combined in situ ellipsometry and ex situ techniques. Particular attention was paid to the properties of the films deposited at low and high laser fluences. At a low laser fluence, the resulting hydrogenated amorphous silicon films display a reduced defect density as compared to unirradiated ones. At laser fluences above the melting threshold, we obtain microcrystalline silicon films with a high surface roughness, as observed by scanning electron microscopy, and high electron mobility, as deduced from time resolved microwave conductivity measurements. The enhanced optical absorption produced by the roughness along with the high electron mobility make these films excellent candidates for photodetection and photovoltaic devices. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semiquantitative subplantation model for low energy ion interactions with surfaces. I. Noble gas ion-surface interactions

    Page(s): 444 - 454
    Save to Project icon | PDF file iconPDF (187 KB)  

    A semiquantitative, phenomenological model for low energy ion interactions with surfaces is developed. The model represents a generalization of the qualitative subplantation model of Lifshitz etal, Phys. Rev. B 41, 10 468 (1989). A general equation for describing ion solid interactions, including film growth processes, is introduced. This model, for the first time, describes the three major contributions to such interactions, i.e., ion penetration, defect production, and radiation enhanced diffusion, in terms of simple analytical equations. In this first article, the basic assumptions of the model are described and the concepts are demonstrated for the example of rare gas ion interaction with graphite. The model is developed in both a simple static form and a more complex dynamic one; the latter is applicable to ion fluence-dependent phenomena. The model provides calculated values of experimentally observable quantities such as the primary ion concentrations retained in the surface and subsurface layers. It also provides estimates of quantities that are difficult to measure such as penetration thresholds, displacement thresholds, and diffusion rates. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semiquantitative subplantation model for low energy ion interactions with surfaces. II. Ion beam deposition of carbon and carbon nitride

    Page(s): 455 - 462
    Save to Project icon | PDF file iconPDF (165 KB)  

    The semiquantitative subplantation model developed in article I of this series [J. Vac. Sci. Technol. A 16, 444 (1998)] is applied to model experimental data for the systems of C+ and N+ ion interactions with graphite, the deposition of diamondlike carbon (DLC) films from C+ ions, and the deposition of carbon nitride (CxNy) films from C+ and N+ ions. The success of the model is based on its ability to provide semiquantitative interpretations of the physical phenomena underlying experimental data from several sources that had previously been interpreted only qualitatively. These phenomena include the effects of ion kinetic energy, ion beam fluence, substrate temperature, radiation enhanced diffusion, penetration thresholds, displacement thresholds, substrate density, and bonding sites. The model allows one to draw previously unexpected conclusions about the interaction mechanisms and to establish quantitative estimates for some previously unknown physical parameters. The results indicate that there is a value of the C+ and N+ ion penetration threshold, ∼7 to 8 eV, which is applicable to graphite, CxNy, and DLC surfaces. The production of sp3 bonded structures is determined by a balance between the beneficial effects (subsurface deposition, enhanced diffusion, densification) and the deleterious effects (damage) of energetic particle beams. © 1998 American- - Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Semiquantitative subplantation model for low energy ion interactions with solid surfaces. III. Ion beam homoepitaxy of Si

    Page(s): 463 - 471
    Save to Project icon | PDF file iconPDF (186 KB)  

    The semiquantitative subplantation model developed in article I [K. J. Boyd, D. Marton, J. W. Rabalais, S. Uhlmann, and Th. Frauenheim, J. Vac. Sci. Technol. A 16, 444 (1998)] is used to describe the homoepitaxial growth of Si{100} films by low energy ion beam deposition. The model successfully describes the epitaxial quality of films grown at a variety of ion energies and substrate temperatures. Density functional molecular dynamics simulations are used to calculate threshold energies and cross sections for penetration of ions into the target lattice. These calculated values, used in conjunction with the model, yield good agreement with recently published experimental data for homoepitaxy by direct deposition of low energy Si+ ions. The model also provides a simple qualitative explanation of the limiting epitaxial thickness in molecular beam epitaxy and the success of epitaxial Si deposition by other hyperthermal particle methods. New insight into the atomic-level behavior of epitaxial film growth from hyperthermal particles is obtained from these applications. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • High energy aluminum ion implantation using a variable energy radio frequency quadrupole implanter

    Page(s): 472 - 476
    Save to Project icon | PDF file iconPDF (121 KB)  

    A high energy aluminum ion implantation using a variable energy radio frequency quadrupole (RFQ) implanter has been studied for the fabrication of high power semiconductor devices. The implanter consists of a microwave ion source with a crucible for AlCl3 sublimation, a sector type mass separator, a magnetic quadrupole triplet, a variable energy four-rod RFQ linac as an additional accelerator, an energy analyzer, and an implantation chamber. Al2+ ions, with energies of 1.0 MeV and 0.9 MeV, are implanted into a 6-inch diameter wafer, and the depth profile and dose uniformity are measured by secondary ion mass spectroscopy and sheet resistivity, respectively. Results show that the depth profile has the desired features for the projected range, and the dose non-uniformity is 0.7%. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Effects of nitrogen ion implantation on the thermal stability of tungsten thin films

    Page(s): 477 - 481
    Save to Project icon | PDF file iconPDF (131 KB)  

    We implanted 6×1016–3×1017 nitrogen ions/cm2 into 100 nm thick tungsten thin films with acceleration energies of 20–60 KeV. As a result, the thermal stability of N+-implanted W thin films is greatly improved from 700 to 900 °C because polycrystalline W thin films change into nanostructured films after N+ implantation. The W thin film implanted at 40 KeV and 3×1017ions/cm2 effectively prevents Cu diffusion after an annealing at 800 °C for 30 min. When the acceleration energy and dosage are higher or lower than this optimum condition, thermal stability of the N+-implanted W film is degraded due to surface damage of Si substrate and partially nanostructured W thin film. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Epitaxial growth of (001)-oriented titanium nitride thin films by N implantation

    Page(s): 482 - 489
    Save to Project icon | PDF file iconPDF (795 KB)  

    The epitaxial growth process of titanium nitride (TiN) films, formed by implanting nitrogen ions (N2+) with 62 keV into 100-nm-thick Ti films grown on NaCl substrates held at 250 °C, has been studied by transmission electron microscopy, Rutherford backscattering spectrometry, and elastic recoil detection analysis. It has been revealed that the (001)-oriented TiNy is epitaxially grown by N implantation into the as-grown (03∙5)-oriented hcp Ti. The TiNy is formed by the transformation of the hcp Ti to (001)-oriented fcc Ti during the N implantation, partially inheriting the atomic arrangement of the square and/or the octahedron of the hcp Ti, as well as the occupation of N in octahedral sites of the fcc Ti. Strain due to the expansion of the lattice and/or the volume of hcp Ti by N implantation can be considered as one of the driving forces for the hcp–fcc transformation of the Ti lattice. The nitriding mechanism of epitaxial Ti thin films is discussed. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Layer-by-layer etching of GaAs (110) with halogenation and pulsed-laser irradiation

    Page(s): 490 - 493
    Save to Project icon | PDF file iconPDF (583 KB)  

    We have investigated the effect of laser irradiation on the terrace morphology of Br-covered GaAs (110). Layer-by-layer etching of GaAs (110) is demonstrated through laser-induced etching and atomic desorption. Nanosecond pulsed-laser irradiation (hν=2.3 eV, pulse power ∼35 mJ cm-2) of Br–GaAs (110) initially produces a high density of small, single-layer etch pits as Br is consumed. Continued laser irradiation causes Ga and As desorption from pit edges so that pits grow and thereby remove the remnant of the top GaAs layer. When there is Br on the surface, pit growth reflects the Br chemisorption structure (elongated along [001]) but subsequent atom desorption favors growth along [11¯0]. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Hot filament chemical vapor deposition diamond growth kinetics on an epitaxial CoSi2 surface monitored by three electron spectroscopies

    Page(s): 494 - 501
    Save to Project icon | PDF file iconPDF (165 KB)  

    Diamond deposition on an epitaxial CoSi2 layer over Si(111) is preceded by the formation of a 4 nm thick silicon carbide layer. The steps of carbide formation, diamond nucleation, and diamond growth are monitored in situ by three electron spectroscopies (x-ray photoelectron spectroscopy, Auger electron spectroscopy, and electron-loss spectroscopy). By comparison with our previous studies of diamond growth on clean Si(100) and Si(111), the time required to stabilize the SiC composition is much longer. This slow step is interpreted by a strong carbon diffusion into the bulk which goes together with silicon enrichment of the carbide phase. The lack of carbon saturation at the surface induces a large delay for the subsequent diamond nucleation process by a time scale factor of 10. In addition, the electron spectroscopy measurements reveal the appearance of C–C sp3 species before the diamond nucleation starts. These species probably correspond to carbon aggregates which act as precursors of the diamond phase. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Platinum etching in Ar/O2 mixed gas plasma with a thin SiO2 etching mask

    Page(s): 502 - 508
    Save to Project icon | PDF file iconPDF (339 KB)  

    Experimental studies of the etching of platinum with a SiO2 etching mask in an Ar/O2 mixed gas plasma were performed. The etching selectivity of platinum to SiO2 increases with the addition of oxygen, and a high etching selectivity of more than 6 is obtained around an oxygen concentration of 10%. This high etching selectivity is caused by the difference in the adsorption of oxygen atoms between platinum and SiO2. In the etching of SiO2 by an Ar/O2 plasma, oxygen atoms are removed by sputtering by incident ions; however, these vacant sites of oxygen are filled immediately by the oxygen atoms incident from the plasma. The surface etching of SiO2 in an Ar/O2 plasma is disturbed by these replacements of the oxygen atoms. On a platinum surface incident oxygen atoms do not stay on the surface, therefore, disturbance of the etching by oxygen adsorption does not occur. This difference in the oxygen adsorption between platinum and SiO2 is confirmed by the x-ray photoelectron spectroscopy analysis of the etched surfaces. By using an Ar/O2 plasma where a high etching selectivity of Pt/SiO2 is obtained, platinum can be etched with thin SiO2 etching masks. By optimizing both the thickness of the SiO2 mask and the - - etching time, platinum can be etched without any residue from the redeposition of the etching products. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Conventional and dynamic actinometry of glow discharges fed mixtures of tetramethylsilane, sulfur hexafluoride, and helium

    Page(s): 509 - 513
    Save to Project icon | PDF file iconPDF (95 KB)  

    Conventional and dynamic actinometric optical emission spectroscopies were used to investigate the composition of discharges of mixtures of tetramethylsilane, sulfur hexafluoride, and helium. Argon was present in a small proportion as an actinometer. Trends in the plasma concentrations of the species H, CH, Si, F, and CF2 were obtained as a function of the proportion of SF6 in the feed, Rs. Dynamic actinometry, which involves monitoring the relative intensities of plasma species following interruption of one of the principal feed gases, gave clues as to the relative importance of gas-phase and plasma/polymer-surface reactions in the production of the measured plasma species. Based on these data, reaction pathways and mechanisms for the production of these species are suggested. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Spatially resolved optical emission study of sputtering in reactive plasmas

    Page(s): 514 - 523
    Save to Project icon | PDF file iconPDF (218 KB)  

    The study of material sputtering under low-pressure reactive ion etching conditions in various gases (Cl2, SiCl4, O2) was performed using optical emission spectroscopy with high spatial resolution. Sputtering-induced secondary photon emission (atomic and molecular) from the processed materials (Si, Al2O3, GaAs) was found to be strongly localized near the target surface. A spatial distribution of atomic line emission intensity was shown to be essentially nonmonotonical with distance from the surface. This effect was explained by a cascade feeding from the upper lying atomic levels, which is enhanced in plasma (collisional) environment. A simplified model accounting for the cascading has been developed, and velocities of sputtered excited atoms (in the range of 2–7×106cm/s) and molecules (about 2–5×105cm/s) have been evaluated from the emission spatial decay parameters. The excited sputtered atoms and molecules are produced in different types of collisions. Fast excited atoms can be produced only in the first few collisions of the incident ion in the surface top layers, whereas excited molecules are knocked off by secondary (slow) atoms originated from a collision cascade inside the solid. Based on this concept of the process, simple expressions for atomic and molecular excitation yields as functions of the incident ion flux and surface coverage were deduced. The technique can be used for in situ surface probing during plasma processing. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Plasma source ion carburizing of steel for improved wear resistance

    Page(s): 524 - 529
    Save to Project icon | PDF file iconPDF (102 KB)  

    Plasma source ion carburizing is a low-temperature, low-pressure carburizing approach for improved wear resistance of steel with specific advantages over plasma carburizing and plasma source carbon ion implantation. A carburizing apparatus based on an electron cyclotron resonance (ECR) microwave plasma source has been developed. Carbon (as methane and hydrogen) ions are accelerated from the ECR plasma by a low-pulsed negative bias (typically -2 kV), which is applied directly to the sample, implanted, and are finally diffused into the steel at elevated temperatures that are regulated up to 550 °C by an auxiliary heater. Plasma source ion carburizing into pure iron and 35CrMo low alloy steel at a process temperature of 350 °C has been investigated. The carburized samples were characterized using Auger electron spectroscopy, electron probe microanalysis, microhardness measurement, and glancing incidence x-ray diffraction. Significant increases in microhardness have been observed on the carburized pure iron and 35CrMo steel, because of 10 μm thick carburized layers composing a Fe3C phase on the outer surface and a hardened diffusion zone in the matrix that were formed after the carburizing at 350 °C for 8 h. The wear tests were performed on a crank/connecting rod reciprocating tribometer in a flat-on-flat configuration. The test results indicate that the carburized 35CrMo steel improved the abrasive wear resistance and decreased the coefficient of friction in comparison with the uncarburized steel.© 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Optimization and characterization of remote plasma-enhanced chemical vapor deposition silicon nitride for the passivation of p-type crystalline silicon surfaces

    Page(s): 530 - 543
    Save to Project icon | PDF file iconPDF (234 KB)  

    In a recent letter [Lauinger etal, Appl. Phys. Lett. 68, 1232 (1996)] we have shown that record low effective surface recombination velocities Seff of 4 cm/s have been obtained at ISFH on low-resistivity (1 Ω cm) p-type crystalline silicon using microwave-excited remote plasma-enhanced chemical vapor deposition (RPECVD) of silicon nitride at low temperature (300–400 °C). As an important application, this technique allows a simple fabrication of rear-passivated high-efficiency silicon solar cells with monofacial or bifacial sensitivity. In this work, we present details of the required optimization of the PECVD parameters and a characterization of the resulting silicon nitride films. All deposition parameters are shown to strongly affect Seff as well as the stability of the films against the ultraviolet (UV) photons of terrestrial sunlight. A clear correlation between Seff and the film stoichiometry is observed, allowing a simple control and even a rough optimization of the surface passivation quality by measurements of the refractive index of the films. An optimum passivation and UV stability is obtained for silicon-rich silicon nitride films with a refractive index greater than 2.3. © 1998 American Vacuum Society. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Modeling of SiO2 deposition in high density plasma reactors and comparisons of model predictions with experimental measurements

    Page(s): 544 - 563
    Save to Project icon | PDF file iconPDF (349 KB)  

    High-density-plasma deposition of SiO2 is an important process in integrated circuit manufacturing. A list of gas-phase and surface reactions has been compiled for modeling plasma-enhanced chemical vapor deposition of SiO2 from SiH4, O2, and Ar gas mixtures in high-density-plasma reactors. The gas-phase reactions include electron impact, neutral–neutral, ion–ion, and ion–neutral reactions. The surface reactions and deposition mechanism is based on insights gained from attenuated total reflection Fourier transform infrared spectroscopy experiments and includes radical adsorption onto the SiO2 surface, ion-enhanced desorption from the surface layer, radical abstractions, as well as direct ion-energy-dependent sputtering of the oxide film. A well-mixed reactor model that consists of mass and energy conservation equations averaged across the reactor volume was used to model three different kinds of high-density plasma deposition chambers. Experimental measurements of total ion densities, relative radical densities, and net deposition rate, as functions of plasma operating conditions, have been compared to model predictions. The results show good quantitative agreement between model predictions and experimental measurements. The compiled reaction set and surface reaction network description was thus validated and can be employed in more sophisticated two- or three-dimensional plasma simulations. © 1998 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