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

Issue 5 • Date Sep 2004

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Displaying Results 1 - 25 of 51
  • Issue Cover

    Page(s): c1
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    Freely Available from IEEE
  • Issue Table of Contents

    Page(s): toc1
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    Freely Available from IEEE
  • Radio frequency line-plasma source using permanent magnets

    Page(s): L7 - L10
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    A high-density and uniform line-plasma source is developed by an inductive rf discharge using a rectangular discharge chamber (200×100×20 mm) with a pair of permanent magnets placed on top and bottom of the chamber. Ion-saturation current-density Jis profile is controlled by varying the width of the magnets and the distance between the antenna and the magnets. A 140-mm-wide plasma [plasma density ≃(1.8-2.5)×1012 cm-3 for electron temperature =4–8 eV] of a uniformity variation within 90% is produced using a 140-mm-long antenna for an Ar pressure of 20 mTorr and a rf power of 3 kW. The measured Jis profiles are explained by solving the equation of motion for electrons under a magnetic field structure of longitudinal line cusps. View full abstract»

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  • High resolution, high speed ultrahigh vacuum microscopy

    Page(s): 1931 - 1947
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    The history and future of transmission electron microscopy (TEM) is discussed as it refers to the eventual development of instruments and techniques applicable to the real time in situ investigation of surface processes with high resolution. To reach this objective, it was necessary to transform conventional high resolution instruments so that an ultrahigh vacuum (UHV) environment at the sample site was created, that access to the sample by various in situ sample modification procedures was provided, and that in situ sample exchanges with other integrated surface analytical systems became possible. Furthermore, high resolution image acquisition systems had to be developed to take advantage of the high speed imaging capabilities of projection imaging microscopes. These changes to conventional electron microscopy and its uses were slowly realized in a few international laboratories over a period of almost 40 years by a relatively small number of researchers crucially interested in advancing the state of the art of electron microscopy and its applications to diverse areas of interest; often concentrating on the nucleation, growth, and properties of thin films on well defined material surfaces. A part of this review is dedicated to the recognition of the major contributions to surface and thin film science by these pioneers. Finally, some of the important current developments in aberration corrected electron optics and eventual adaptations to in situ UHV microscopy are discussed. As a result of all the path breaking developments that have led to today’s highly sophisticated UHV–TEM systems, integrated fundamental studies are now possible that combine many traditional surface science approaches. Combined investigations to date have involved in situ and ex situ surface microscopies such as scanning tunneling microscopy/atomic force microscopy, scanning Auger microscopy, and photoemission electron microscopy, and area-integrating techniques such as x-ray ph- - otoelectron spectroscopy, ultraviolet photoelectron spectroscopy, Auger electron spectroscopy, low-energy electron diffraction, temperature programmed desorption, high-resolution electron energy-loss and Fourier-transform infrared spectroscopies, and others. Material systems ranging from atomic layers of metals and semiconductors to biology related depositions are being investigated. In the case of biological materials, however, strict limitations to high-resolution applications are imposed by electron radiation damage considerations. View full abstract»

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  • Generation of low-energy neutral beam for Si etching

    Page(s): 1948 - 1955
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    As the feature size shrinks toward the nanoscale, charge-up damage from ion-induced etching becomes a very serious problem. Neutral beam etching is one of the most popular techniques used to reduce charge-up damage. We have performed a neutral beam simulation to optimize the neutral beam, which is generated by collisions between ions produced by a plasma source with an ion gun and low angle reflectors. An ion gun is simulated using the two-dimensional Xgrafic object oriented particle-in-cell (XOOPIC) code to obtain a higher ion flux and to improve the directionality of ions. For neutral beam simulation, we use the modified XOOPIC code to which reflection data obtained by the transport of ions in matter (TRIM) code are appended. Neutral flux, energy and angle distributions, which have an influence upon the etch rate, are calculated in the neutral beam simulation. A low-energy neutral beam from an ion gun with two grids has a low neutral flux and a broad angle distribution. Therefore, we propose a three-grid ion gun that has one additional grid with positive voltage, allowing independent control of the ion flux and ion energy. By increasing the ion flux, the neutral flux by three grids is three times larger than that by two grids. The neutral beam source using a three-grid ion gun has several advantages for trench etching: increased etch rate, decreased sidewall etching, and reduced variation in the etch rate as the trench size changes. A low-energy neutral beam source using the three-grid ion g 0un and low-angle reflectors is experimentally tested. View full abstract»

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  • Infrared reflectance of GaN1-xPx ternary alloys grown by metalorganic chemical vapor deposition

    Page(s): 1956 - 1961
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    Infrared (IR) reflection spectra of GaN1-xPx alloys, grown by light-radiation heating, low-pressure metalorganic chemical vapor deposition, have been investigated with phosphorus composition x=0–0.15. A multi-oscillator model has been used to fit the IR reflection spectra. In addition to the demonstration of a GaN-like transverse-optical (TO) mode, a GaP-like TO mode, located at about 355 cm-1, has been identified for x≫0, showing a typical two-mode behavior. With the increment of x the frequency of the GaN-like TO phonon decreases and the GaP-like TO phonon keeps its frequency almost unchanged within the measured composition range. A simple random-element-isodisplacement model has been employed to interpret the frequency change of both GaN-like and GaP-like phonons with the phosphorous composition x. The damping of the GaN-like TO mode increases significantly with x and is explained by the disorder effect resulting from the introduction of foreign P atoms. View full abstract»

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  • Interpretation of stress variation in silicon nitride films deposited by electron cyclotron resonance plasma

    Page(s): 1962 - 1970
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    We report here on internal stress variations in SiNx films deposited on silicon by plasma enhanced chemical vapor deposition-electron cyclotron resonance (PECVD-ECR) plasma. The effects of deposition parameters, film thickness and surface morphology have been considered. SiNx films can exhibit a compressive or a tensile internal stress, ranging from -1970 to +465 MPa, depending on deposition parameters. Among published results, usual reported residual stress for PECVD films is compressive. Versatility of our experimental ECR equipment allows one to deposit films exhibiting a weak stress in the range of a few tens MPa. On the basis of atomic force microscopy observations, a correlation between the intensity of the stress and the granular morphology of the films has been observed. The rms value for SiNx film surfaces is never higher than 1.5 nm, with a grain height ranging from 1.2 to 5 nm and a grain width varying from 20 to 60 nm. Both the grain size and the residual stress vary with the thickness of the films. This work highlights the influence of the initial surface properties on the deposition mechanism. An exhaustive review of the stress generation model is given and a tentative interpretation for the origin of stress, either compressive or tensile, is proposed. View full abstract»

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  • Microstructure and Mg concentration of Mg–Si thin film deposited by ion beam sputtering on glass substrate

    Page(s): 1971 - 1974
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    Mg–Si thin films are deposited by ion beam sputtering from the target composed of Mg and Si with 50%:50% area ratios. Intermetallic compound magnesium silicide (Mg2Si) films are obtained at room temperature on glass substrates. Observation of the thin film by cross sectional transmission electron microscopes indicates that films of 1 μm thickness show a microstructure composed of a crystalline upper layer of Mg2Si with columnar structure 300 nm thick and an amorphous bottom layer with uniform structure 700 nm in thickness. Energy dispersive x-ray measurements show that magnesium concentration in the crystalline Mg2Si upper layer are larger than in the amorphous bottom layer. Moreover, the magnesium concentration at grain boundaries is larger than that in grains in the crystalline Mg2Si upper layer. It is also observed that magnesium segregates on the film surface. The film formation is explained in terms of magnesium migration-to-surface and magnesium evaporation from film surface. View full abstract»

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  • Optical properties of tantalum nitride films fabricated using reactive unbalanced magnetron sputtering

    Page(s): 1975 - 1979
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    Coatings of tantalum nitride with various compositions were deposited on silicon substrates using unbalanced reactive magnetron sputtering. An optical emission spectrometer was used to monitor the ratio of tantalum to nitrogen particles in the plasma in real time. The coatings were characterized using x-ray diffraction (XRD), x-ray photoelectron spectroscopy (XPS), and spectroscopic ellipsometry (SE). The primary nitride phases (Ta, Ta2N, TaN) in the films were determined using XRD and XPS. The elemental composition was revealed from XPS measurements. The refractive indices were deduced from analysis of the SE data, which were subsequently simulated using the Drude–Lorentz model. The resistivity and electron mean free paths were deduced from this simulation and were correlated to the film composition and microstructure. The resistivity increased whereas the electron mean free path decreased with an increase in nitrogen content or a decrease in grain size. View full abstract»

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  • Evaluation of Schottky barrier height of TiN/p-type Si(100)

    Page(s): 1980 - 1983
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    Zero-bias Schottky barrier height Bp) of reactive-sputtered TiN (∼40 nm) on p-type Si(100) was determined at room temperature and the effect of heat treatment was investigated by forward current–voltage (I–V) measurements. The TiN remained amorphous following annealing. The zero-bias barrier heights for the as-deposited and annealed specimens were in the range of 0.53–0.64 V. The lower ΦBp values of 0.53–0.54 V are related to as-deposited and 673 K annealed specimens, whereas the 0.62–0.64 V values refer to samples annealed at 773–783 K. Forward I–V measurements of as-deposited (300 K) TiN/Si diodes were performed in the temperature range of 220–285 K. The barrier height was determined by the activation energy method, resulting in ΦBp=0.58 V. View full abstract»

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  • Real-time acoustic sensing and control of metalorganic chemical vapor deposition precursor concentrations delivered from solid phase sources

    Page(s): 1984 - 1991
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    We have investigated the performance and potential benefit of acoustic sensing for real-time monitoring and closed loop control of binary gas mixture compositions delivered from low vapor pressure metalorganic sources. Two solid phase sources were investigated in the presence of H2 as a carrier gas: (1) trimethylindium (TMI) and (2) bis(cyclopentadienyl) magnesium (Cp2Mg), which have room temperature (25°C) vapor pressures of 2.5 and 0.04 Torr, respectively. An acoustic sensor was implemented on the gas feed line to measure the concentration-dependent speed of sound in the gas mixture. This enabled sensitivity and control at precursor levels as low as 0.6 ppm in H2. Closed loop process control was implemented to maintain TMI and Cp2Mg concentration target in the presence of intentionally introduced long term temperature drifts. Despite induced variations of the precursor vapor pressure up to 50%, the delivered composition was controlled to within ±0.15% for TMI (at 0.5 mol% set point) and ±0.3% for Cp2Mg (at 0.01 mol% set point). Short term variability could also be substantially reduced by the control scheme. This work demonstrates the feasibility of sensor-driven control systems for stable delivery of low vapor pressure, normally problematic precursor materials. In turn, this opens the door to utilization of a broader range of species which can be synthesized as chemical precursors. View full abstract»

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  • Wide range flow sensor—Vacuum through viscous flow conditions

    Page(s): 1992 - 1999
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    An intelligent molecular flow sensor [see Note (1) on next page] enables direct gas flow measurements in the transitional and molecular flow regimes, as well as in the slip and continuum flow regimes, thereby enabling flow measurements at pressures ranging from vacuum through atmospheric. The properties of this sensor are investigated, along with the sensor’s transitional operating ranges. The IMFS operates as a mass flow sensor (directly measures the mass flow) in the transitional and molecular flow regimes, and it operates as a volumetric flow sensor in the continuum and slip flow regimes. Understanding of these properties and ranges of operation are critical for demanding leak testing, sealed closure integrity testing and vacuum test applications. View full abstract»

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  • Effect of nano-crystallization of high velocity oxy-fuel-sprayed amorphous NiCrBSi alloy on properties of the coatings

    Page(s): 2000 - 2004
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    NiCrBSi self-fluxing alloy coatings were deposited by high velocity oxy-fuel (HVOF) spraying. Annealing treatment was applied to the as-sprayed coatings to develop the microstructure of the Ni-based coating. The microstructure of the coating was characterized using optical microscopy, x-ray diffraction and transmission electron microscopy. The crystallization behavior of the amorphous coating was also characterized by differential scanning calorimetry. The properties of the coating were characterized by microhardness and abrasive wear tests. The results showed that the as-sprayed HVOF coating deposited by well melted spray particles exhibited a dense microstructure of amorphous phase. It was revealed that the crystallization of the amorphous phase in HVOF NiCrBSi coating occurs at a temperature of about 502°C. Annealing at temperature a little higher than recrystallization temperature leads to the formation of the nano-crystalline microstructure. The subsequent nanostructured Ni-based coating presents higher microhardness and excellent wear performance. With the further increase in annealing temperature, the growth of the nano-crystalline grains occurs and, accordingly, the microhardness of the coating and the wear performance decrease. Thereafter, the microstructure and properties of the Ni-based self-fluxing alloy coating can be controlled through postannealing treatment. View full abstract»

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  • Organosilane self-assembled monolayers directly linked to the diamond surfaces

    Page(s): 2005 - 2009
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    An amino-terminated self-assembled monolayer (SAM) was prepared from p-aminophenyltrimethoxysilane (H2N(CH)6Si(OCH3)3, APhS) on diamond substrates irradiated by vacuum ultraviolet (VUV) light (wavelength: 172 nm) through chemical vapor deposition. Furthermore, the APhS-SAM was irradiated by VUV light in air. After the VUV irradiation, only one layer of siloxane (SiOx) was left as a result of the selective decomposition of organic compounds. APhS-SAM was reprepared on the SiOx surface. The evidence as to the respective processes was clearly obtained by x-ray photoelectron spectroscopy (XPS) and water contact angle measurements. Based on the chemical bonding states analysis, APhS-SAMs were confirmed to be directly linked to the diamond substrates and SiOx layers with bonding types of SiOC and SiOSi, respectively. The compositions obtained by XPS measurement indicate that the thickness of the SiOx layer was increased gradually by repeating the APhS-SAM formations and VUV irradiations in this order. Finally, we are successful in controlling the nano-scale thickness of the SiOx layer, which is the interface between APhS-SAMs and diamond substrates. View full abstract»

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  • Dielectric response of asymmetric KNbO3/KTaO3 superlattices

    Page(s): 2010 - 2013
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    The synthesis and properties of asymmetric KNbO3/KTaO3 superlattices is examined. Interdigitated electrodes are fabricated for temperature-dependent capacitance measurements. The nonlinear dielectric response of 1/N superlattice exhibits the anomalous positive tunability behavior indicative of antiferroelectricity. In contrast, the N/1 KNbO3/KTaO3 structures (N≫1) appear to be either ferroelectric or paraelectric, depending on the temperature. Discussion of possible mechanisms for this behavior is given. View full abstract»

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  • Neutral gas temperature measurements within transformer coupled toroidal argon plasmas

    Page(s): 2014 - 2021
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    Spatially resolved neutral gas temperature of Ar plasmas within a new type of transformer-coupled toroidal plasma source was measured by fitting unresolved rovibrational bands of trace gas N2 (C 3Πu→B 3Πg). With power density as high as 4.8 W/cm3, the maximum neutral gas temperature inside Ar plasmas was found to be 2000 K. The position with maximum neutral gas temperature was off the center of the cross section and close to the ferrite core, where higher electric field contributes to higher heating power. The dependence of neutral gas temperature on pressure was measured and can be empirically fitted by proportionality between gas temperature and logarithm of the pressure, as found by other researchers. A simple physical model gives the dependence of pressure as the sixth order of neutral gas temperature, which fits the experimental data as well. It was also found that added N2 gas perturbed Ar plasmas obviously, and therefore we recommend adding less than 1% N2 as trace gas. There is no dependence of fitted neutral gas temperature on the optical resolution of monochromator, as would be expected. View full abstract»

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  • Pressure field in a tube with a general and arbitrary time- and position-dependent gas source

    Page(s): 2022 - 2026
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    In this article we present analytical and numerical results for a pressure profile along the axis of a tube with a general and arbitrary time- and position-dependent gas source. The model is able to determine the pressure values along the tube, once the pumping speed at each extremity and the gas sources are specified. The time evolution of the pressure along a tube is presented for situations commonly found in high-vacuum applications, such as particle accelerators, colliders, storage rings, and synchrotron light sources. View full abstract»

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  • Design and performance of a molecular beam epitaxy system for metallic heterostructure deposition illustrated by a study of the controlled epitaxy of Cu(111)/Al2O3(0001)

    Page(s): 2027 - 2034
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    We describe the design and construction of an ultrahigh-vacuum molecular beam epitaxy (MBE) system for the growth of metallic heterostructures, particularly magnetic metals, and alloys. The system, which was specifically designed to be both cost-effective and compact, incorporates an “axial” design with a large source to substrate distance (≫69 cm) to meet demands for high uniformity, low deposition rate, and compatibility with nanolithographic masks and templates. The growth and in situ characterization capabilities are specifically tailored to metallic film growth allowing for greatly reduced costs in comparison to commercial MBE systems. We demonstrate the performance of the system via a study of the controlled epitaxy of Cu(111) on Al2O3(0001), a useful substrate/buffer layer combination for the growth of many magnetic transition metals and their alloys. Exploiting the three-dimensional nature of the growth at room temperature we are able to control the in-plane crystallite size, independent of the surface roughness, by varying the deposition rate. View full abstract»

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  • Atomic layer deposition and characterization of hafnium oxide grown on silicon from tetrakis(diethylamino)hafnium and water vapor

    Page(s): 2035 - 2040
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    In this work thin films of hafnium oxide are deposited on Si(100) substrates by means of atomic layer deposition (ALD) using tetrakis(diethylamino)hafnium and water vapor at substrate temperatures of 250–350ºC. Our system capabilities include fast transient delivery of reactive fluids, real-time vapor phase detection (in situ tunable diode laser hygrometer), precursor thermochemical capabilities, and ppt level elemental analysis by inductive coupling plasma mass spectrometry. The composition, purity, and other properties of the films and resulting interfaces are determined using x-ray and Fourier transform infrared spectroscopies, Z-contrast imaging and electron energy loss spectroscopy in a scanning transmission electron microscope with Å scale resolution, and spectroscopic ellipsometry. The observed ALD rate is ∼1.4 Å per cycle. The nonuniformity across the film is less than 4%. Negligible carbon contamination is found in the resulting stoichiometric films under all conditions studied. The pulse sequence was optimized to prevent disastrous particulate problems while still minimizing purge times. The film deposition is investigated as a function of substrate temperature and reagent pulsing characteristics. A mild inverse temperature dependence of the ALD rate is observed. The initial stage of the HfO2 growth is investigated in detail. View full abstract»

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  • Influence of substrate bias on practical adhesion, toughness, and roughness of reactive dc-sputtered zirconium nitride films

    Page(s): 2041 - 2047
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    The ZrN films were grown on Si (100) substrates using dc magnetron sputtering where the substrate bias was varied from -45 to 50 V. In this article, the film/substrate practical adhesion of the ZrN films were measured by scratch testing while the hardness, elastic modulus, and fracture toughness were measured by nanoindentation. The structures and morphologies of the ZrN films were analyzed using scanning electron microscopy, atomic force microscopy, and x-ray diffraction. The results indicate that the introduction of either negative or positive bias results in the degradation of the practical adhesion properties, while the films under zero bias exhibit the best adhesion. In addition, positive bias results in the increase in both the hardness and elastic modulus, while negative bias enhances the hardness and toughness of the ZrN thin films. The mechanical properties are greatly influenced by substrate bias and can be correlated to microstructure variations. The detailed mechanisms accounted for these phenomena are discussed. View full abstract»

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  • Relationship between optical properties and microstructure of CeO2SiO2 composite thin films

    Page(s): 2048 - 2051
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    CeO2SiO2 composite thin films were prepared by e-beam evaporation and ion beam assisted deposition using an End-Hall ion source. The refractive index of composite thin films exhibited a maximum value at 20%–35%SiO2 fraction, indicating the high packing density. Optical analysis revealed that the transmittance and reflectance spectra of composite films were consistent with the results of the refractive index. The results from x-ray diffractometry, atomic force microscopy and scanning electron microscopy measurements showed that composite thin films containing 20%–35%SiO2 concentration had a dense and smooth amorphous surface, compared to the roughened granular structure of the pure SiO2 and CeO2 thin films. The composite thin films with 20%–35%SiO2 concentration exhibited a higher resistance to water absorption than the CeO2 thin films in spite of the highest refractive index. View full abstract»

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  • Sub-100 °C a-Si:H thin-film transistors on plastic substrates with silicon nitride gate dielectrics

    Page(s): 2052 - 2055
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    Fabrication on thin-film transistors (TFTs) on flexible plastic substrates for large-area imagers and displays has been made possible by lowering the deposition temperatures, which reduces the thermal deformation of plastic substrates, greatly facilitating substrate preparation and device patterning. Furthermore, at extremely low deposition temperatures, much wider variety of low-cost substrates, plastics or otherwise, are available for use. In this article, we report on a-Si:H TFTs fabricated at 75 °C on glass and plastic substrates. The TFTs were fabricated using inverted–staggered topology, in a full wet etch process. The TFT structures consisted of 140 nm of sputtered Mo for gate, 380 nm of plasma-enhanced chemical vapor deposition (PECVD) a-SiNx:H gate dielectric optimized for 75 °C, 50 nm of PECVD a-Si:H channel material, 50 nm of PECVD n+ a-Si:H for source/drain contacts, and sputtered Al for contact metallization. Current–voltage characteristics were measured, and relevant transistor parameters were calculated. TFTs exhibited the leakage current below 10-12 A, and on/off current ratio exceeding 105. The results were compared to those for high temperature a-Si:H TFTs, and the differences are discussed. View full abstract»

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  • Contribution and origin of H3O+ in the mass spectral peak at 19 amu

    Page(s): 2056 - 2060
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    Typically, the mass spectral peak observed at 19 amu in residual gas analyzers at very high vacuum (VHV) and ultrahigh vacuum (UHV) has been attributed to fluorine. Using Fourier transform mass spectrometry (FTMS), the presence of the hydronium ion H3O+ has been fully resolved from F+. Correlation of the mass 19 signals for a conventional quadrupole mass spectrometer (QMS) and the FTMS, positioned adjacent, unambiguously indicates hydronium as the source of mass 19. At partial pressures of H2O in the VHV range and higher there is sufficient density for the formation of the hydronium ion through ion–molecule interactions. Formation of the hydronium was found to directly correlate with the partial pressure of H2O. However, in a QMS, formation of H3O+ in UHV appears to occur principally by electron stimulated desorption (ESD). Dosing the system with hydrogen from 1 L exposure to saturation (1×10-6 Torr for 8 h) was found to increase the H3O+ ESD yield detected by the QMS by as much as a factor of 10. The initial hydronium ESD cross section from a hydrogen saturated grid was estimated to be σ∼1×10-19 cm2. In a separate experiment, time of flight–secondary ion mass spectrometry sputter yields from the stainless steel grid of a quadrupole mass spectrometer also showed small signals of H3O+, a- - s well as its constituents, H+, O+ and OH+, but no F+. View full abstract»

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  • Laser-triggered hollow-cathode plasma process for film growth

    Page(s): 2061 - 2066
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    A method of generating a pulsed plasma plume of metallic species using a hollow-cathode arc discharge arrangement is presented. Electrical energy from a pulse-forming network (PFN) generates the transient plasma that evaporates material from the anode that is placed inside a hollow cathode. The discharge is triggered by thermionic electrons produced by a CO2 laser pulse that impinges on one of the electrodes. This plasma process has been used to deposit carbon films in a low-pressure argon or nitrogen ambient. Current pulses of 4–10 ms in duration with peak currents of 350 A have been produced by the PFN. Characteristics of the produced plasma have been studied by optical emission spectroscopy. The amount of energy imparted to the argon plasma is more than that for a nitrogen plasma. Comparison of on-axis intensity for the 426.9 nm line of C+ for the two plasmas shows that the density of carbon ions generated in the nitrogen plasma is higher than that in the argon plasma. Films deposited by this method have fairly uniform thickness profiles that are of the form cos0.4 θ for the argon plasma and cos2.2 θ for the nitrogen plasma. This indicates that the nitrogen plasma is more forward directed than the argon plasma. Deposition rates of about 10–16 Å/pulse have been obtained for carbon films. View full abstract»

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  • Chemical state of nitrogen in a high nitrogen face-centered-cubic phase formed on plasma source ion nitrided austenitic stainless steel

    Page(s): 2067 - 2070
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    A single high nitrogen face-centered-cubic phase N) was formed on the plasma source ion nitrided 1Cr18Ni9Ti (18-8 type) austenitic stainless steel. Auger electron spectroscopy and x-ray photoelectron spectroscopy, in conjuction with ion beam sputtering, were used to determine the chemical composition and bonding of nitrogen in the γN phase. The chemical composition of the γN phase was shown as a formula with atomic fraction (Fe0.60,Cr0.22,Ni0.18)2N. The γN phase possessed weaker Cr–N ionic-type bonds and stronger Fe–N ionic-type bonds, compared with the stoichiometric nitrides. The Cr 2p3/2 binding energy was 1.1 eV lower than that of CrN and Cr2N phases (at 575.5 eV). The chemical shift of the Fe–N bonding compared with the Fe–Fe bonding was nearly 2.1 eV. The N 1s binding energies showed that the nitrogen was in the chemical state with iron (at 396.6 eV) and chromium (at 397.7 eV). All the chromium appeared to be in the Cr–N bond. A part of iron was also observed in the nitride state, and all the nickel was contained in the metallic state. View full abstract»

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

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G. Lucovsky
North Carolina State University