Showing papers in "Journal of Vacuum Science and Technology in 1982"
TL;DR: In this article, the location of points on the plots can be understood on the basis of polarizability of the environment (on the Auger parameter grid of lines, slope +1) and on the factors contributing to the energy of the final state ion in the auger transition (a grid of line, slope −1).
Abstract: Silicon–oxygen and aluminum–oxygen compounds exhibit significant XPS Auger and photoelectron chemical shifts that are accurately measurable. Chemical state plots of KLL Auger kinetic energy versus 2p photoelectron energy permit identification of chemical species from the locations of their points on the plots. The KLL Auger electrons of Al and Si were generated by the bremsstrahlung component of the radiation, with conventional instrumentation. The location of points on the plots can be understood on the basis of polarizability of the environment (on the Auger parameter grid of lines, slope +1) and on the basis of the factors contributing to the energy of the final state ion in the Auger transition (a grid of line, slope −1). Tetrahedral aluminum has a significantly smaller Auger parameter than octahedral aluminum, and this difference is repeated, but with reduced magnitude on the similar plots for silicon and oxygen lines for the same compounds. Otherwise, the Auger parameters for this class of compounds...
707 citations
TL;DR: In this paper, the authors investigated the internal stresses, electrical resistivities, optical reflectances, and microstructures of metal and semiconductor films sputtered from cylindrical post magnetron sources.
Abstract: Extensive investigations of the internal stresses, electrical resistivities, optical reflectances, and microstructures of metal and semiconductor films sputtered from cylindrical‐post magnetron sources have established the existence of a universal transition phenomenon for these properties that depends sensitively upon the pressure of the sputtering gas and its mass relative to that of the target material. At low working pressures the sputtered films generally have compressive stresses and near bulk‐like values of their resistivity and optical reflectance. Little change is observed as the working pressure is raised, until a transition pressure is reached at which rapid changes in the deposited film properties begin to occur. The transition pressures for the various elements increase in a regular way with their atomic masses. A preliminary study by one of the authors also indicated that the values of the transition pressures were sensitive to the geometry of the sputtering source, being lower for sources o...
248 citations
TL;DR: In this paper, the technology of broad-beam ion sources used in sputtering applications is reviewed, and the most frequently used discharge chambers are described, together with procedures for predicting performance.
Abstract: The technology of broad‐beam ion sources used in sputtering applications is reviewed. The most frequently used discharge chambers are described, together with procedures for predicting performance. A new, compact ion source is described. Ion acceleration is reviewed, with particular emphasis on recent low‐energy techniques. Some of these techniques include three‐grid, small‐hole two‐grid, and one‐grid ion optics. A new material for fabrication of high‐precision ion optics is silicon. Because no stresses are introduced with the etching techniques used, the finished grid can be held to very close tolerances. A recent innovation for sputtering applications is the use of Hall‐current acceleration. This technique uses a magnetic field interacting with an electron current to provide the accelerating electric field, thereby avoiding the usual space‐charge limit on ion current density that is associated with gridded optics. Electron emission is also reviewed, with new hollow cathodes promising improved lifetimes. The overall picture is one of greatly improved ion source capability, with particularly large improvements in low‐energy ion current densities.
243 citations
TL;DR: The development of broad-beam ion source technology described in the companion paper (Part I) has stimulated a rapid expansion in applications to materials processing such as microfabrication and reactive ion beam etching.
Abstract: The developments in broad‐beam ion source technology described in the companion paper (Part I) have stimulated a rapid expansion in applications to materials processing. These applications are reviewed here, beginning with a summary of sputtering mechanisms. Next, etching applications are described, including microfabrication and reactive ion beam etching. The developing area of surface layer applications is summarized, and related to the existing fields of oxidation and implantation. Next, deposition applications are reviewed, including ion‐beam sputter deposition and the emerging technique of ion‐assisted vapor deposition. Many of these applications have been stimulated by the development of high current ion sources operating in the energy range of tens of hundreds of eV. It is in this energy range that ion‐activated chemical etching is efficient, self‐limiting compound layers can be grown, and the physical properties of vapor‐deposited films can be modified. In each of these areas, broad ion beam techn...
207 citations
TL;DR: In this article, a planar magnetron system with controlled Ar/O2 gas mixtures was used for sputtering a Zn target in an unheated glass substrate, which was either stationary in front of the target or in constant motion.
Abstract: ZnO films have been prepared by rf sputtering a Zn target in a planar magnetron system with controlled Ar/O2 gas mixtures. The films were deposited on unheated glass substrates which were either stationary in front of the target or in constant motion. Both the system pressure and plasma impedance changed when an oxide layer formed on the target surface. This occurred at an oxygen flow rate which increased almost linearly with rf power; at 500 W, the required flow rate was 9 ml/min and the pressure increased from 0.1 to 1.2 Pa due to the reduced oxygen gettering. High resistance ZnO films were deposited at oxygen flow rates above this threshold value. The target self‐bias voltage increased by 30 V at this value; it is affected by both the system pressure and the power. The deposition rate increased linearly with power at approximately 0.03 (μm/min)/(W/cm2) which appears to be typical of sputtering from a ZnO layer or target. For continuous substrate motion, the average rate was approximately 7% of this val...
184 citations
TL;DR: In this paper, preparation of silicon nitride film with small tensile stress and low refractive index was investigated as a function of deposition temperature and reactant gas ratio (SiH2Cl2/NH3).
Abstract: In LP‐CVD process, preparation of silicon nitride film with small tensile stress and low refractive index was investigated as a function of deposition temperature and reactant gas ratio (SiH2Cl2/NH3). The small stress film with low refractive index can be prepared easily by high temperature deposition. Applying the film to an x‐ray mask membrane, a new silicon nitride single‐layer x‐ray mask with a large area window (such as 50 mm in diameter) and high transparency to visible light is realized. Using this mask, a submicron resist pattern (0.5 μm line and space) can be replicated easily by Si–K x‐ray exposure system.
182 citations
TL;DR: The formation of TiN thin films by doping Ti with N2 during evaporation at room temperature and by following with high-temperature (700-900°C) annealing was confirmed by x-ray analysis as mentioned in this paper.
Abstract: The formation of TiN thin films by doping Ti with N2 during evaporation at room temperature and by following with high‐temperature (700–900 °C) annealing was confirmed by x‐ray analysis This is different from conventional reactive sputtering and is compatible with lift‐off processes in pattern delineation It has been observed that when Ti is heavily doped with N on a silicon substrate, the reaction between Ti and Si which forms TiSi2 is totally suppressed during high‐temperature annealing and forms TiN only On the other hand, if a thin layer of pure Ti was evaporated on a Si substrate before the introduction of N2, then a composite film of TiN/TiSi2 was formed with a clear boundary between them after high‐temperature annealing The thickness of each layer can be well controlled by the initial evaporation thickness In both cases, Al was deposited on top Rutherford backscattering studies showed that TiN is an effective diffusion barrier up to 550 °C for 30 min of annealing and forms an ideal contact barrier between Al and Si
173 citations
TL;DR: In this article, disordered AlAs films grown by MBE and cleaned with light Ar+ sputtering have been oxidized with various exposures of O2 and H2O at room temperature and studied with XPS.
Abstract: AlAs films grown by MBE and cleaned with light Ar+ sputtering have been oxidized with various exposures of O2 and H2O at room temperature and studied with XPS. Analysis of XPS at various exposures of the disordered AlAs surfaces showed the formation of an Al2O3 layer with the loss of As leaving what has tentatively been assigned as As0 within and on the Al2O3 layer. Oxidation of the As was not observed until after heavy O2 exposures (∠1011L). The rate of Al2O3 formation on the disordered AlAs film was found to be approximately comparable to that on metallic Al. Oxide formation by H2O exposure was found to be about four times faster than with O2.
166 citations
TL;DR: In this paper, the effect of ion bombardment on film stress was studied by evaporating Nb thin films in the presence of a controlled ion beam from a Kaufman ion source, where films were deposited at 4 A/s by electron-beam evaporation with ion bombardment over the energy range 100-800 eV, at ion current densities of 0.001 to 1.1 mA/cm2.
Abstract: The effect of ion bombardment on film stress was studied by evaporating Nb thin films in the presence of a controlled ion beam from a Kaufman ion source. Films were deposited at 4 A/s by electron‐beam evaporation with ion bombardment over the energy range 100–800 eV, at ion current densities of 0.001 to 1.1 mA/cm2. Film stress was measured by an x‐ray bending‐beam technique on Si substrates. Stress values were found to depend strongly on both ion flux and sample temperature. For films deposited at 400 °C, film stress is tensile in the absence of ion bombardment. Increasing argon ion flux causes a change toward compressive stress, in some cases passing through zero. For films deposited at room temperature, film stress is compressive in the absence of ion bombardment, due to incorporation of oxygen. Argon ion bombardment causes a change toward tensile stress, correlating with an improvement in film purity by preferential resputtering of oxygen. With 100 eV argon ions, an ion‐to‐atom ratio of only 3–10 % is ...
147 citations
TL;DR: In this paper, the authors show that the use of doubly occupied orbital wavefunctions, such as the closed shell Hartree-Fock (HF), leads to an asymmetric dimer description of the Si(100) surface.
Abstract: Theoretical cluster calculations for the Si(100) surface show that the use of doubly occupied orbital wavefunctions, such as the closed‐shell Hartree–Fock (HF), lead to an asymmetric dimer description of the surface. The inclusion of electron correlation produces a symmetric dimer description with a ground state ∠1.0 eV below the minimum of the HF buckled dimer. There are two low‐lying states of the symmetric dimer (a singlet and a triplet) with very different geometries. Energy minimization calculations indicate that a (2×1) structure is favored over a c(2×2) structure. We also report ionization potentials for surface and Si(2p) core electrons that are consistent with current experimental data.
141 citations
TL;DR: In this article, a combination of analytical techniques (spectroscopic ellipsometry, Auger spectroscopy, and scanning electron microscopy) have been used to study the etch rates, the surface composition and morphology.
Abstract: Hydrogen plasmas have been used to etch surfaces of semiconducting materials (e.g., GaAs, GaSb, InP, Si), their oxides, and Si nitride. Using a combination of analytical techniques—spectroscopic ellipsometry, Auger spectroscopy, and scanning electron microscopy (SEM), the etch rates, the surface composition and morphology have been studied. It is demonstrated that the selective etching rate of hydrogen plasma for Si over SiO2 is ∠30, and that for GaAs oxide over GaAs is ∠2. It is also shown that the hydrogen plasma etched (and air exposed) GaAs surfaces have a Ga/As concentration ratio nearly equal to that of the air cleaved GaAs surface. Similar results have also been obtained for GaSb. Hydrogen plasma etched InP shows surface segregation and is rich in In. The etch rates of the semiconductors and their oxides vary by several orders of magnitude from compound to compound as determined from ellipsometry and SEM. It is also demonstrated that scanning ellipsometry can be used to monitor surface etching proc...
TL;DR: In this article, the effects of low-energy particle bombardment on growing films during vapor phase epitaxy are considered in some detail, and the results on the growth of unique single-crystal metastable semiconducting alloys are discussed.
Abstract: The effects of low‐energy particle bombardment of growing films during vapor phase epitaxy are considered in some detail. Ion bombardment plays an important and sometimes dominant role in controlling the growth kinetics and physical properties of films deposited by glow discharge and ion beam sputter deposition, molecular beam epitaxy using accelerated dopants, and plasma‐ assisted chemical vapor deposition. Ion–surface interaction effects, including trapping, sputtering, preferential sputtering, and collisional mixing, are used to interpret and model experimental results concerning the effects of low‐energy particle bombardment on nucleation, film growth, enhanced diffusion at interfaces, and elemental incorporation probabilities. Finally, recent results on the growth of unique single‐crystal metastable semiconducting alloys are discussed.
TL;DR: In this article, a technique for maskless writing of metal films with submicrometer dimensions is described, where an ultraviolet beam from a cw or pulsed laser is used to photodissociate an organometallic gas near a gas-solid interface, and the liberated metal atoms then condense in an area of dimensions comparable to the laser spot size.
Abstract: A technique for maskless writing of metal films with submicrometer dimensions is described. An ultraviolet beam from a cw or pulsed laser is used to photodissociate an organometallic gas near a gas–solid interface. The liberated metal atoms then condense in an area of dimensions comparable to the laser spot size. Experiments which elucidate the essential physics of the process have been performed.
TL;DR: In this paper, the authors present the application of deep-level transient spectroscopy (DLTS) for characterizing interface states on metal-insulator-semiconductor capacitors, with emphasis on the constant-capacitance (CC) mode of measurement.
Abstract: Localized electronic states at the semiconductor–insulator interface adversely affect the operation of insulated‐gate, field‐effect devices. Characterization of interface states provides essential information for minimizing their effect through process optimization, for predicting device performance, and ultimately for microscopic identification of interface defects. This paper reviews the application of deep‐level transient spectroscopy (DLTS) for characterizing interface states on metal–insulator–semiconductor capacitors, with emphasis on the constant‐capacitance (CC) mode of measurement. The DLTS measurement yields both the energy distribution of interface states and their cross section for capturing free carriers. In addition, it has the versatility of being applicable to both interface and bulk defect characterization. The CC‐DLTS technique offers the combined features of high sensitivity (<1×109 eV−1 cm−2), minimum signal distortion at high defect densities, high energy resolution, and the determina...
TL;DR: In this paper, MOS capacitors were formed on silicon substrates and their electrical properties were evaluated by capacitance-voltage (C‐V) measurements, which indicated a midgap density of surface states NSS = 2×1011 cm−2eV−1 for SiO2 layers deposited at 300°C.
Abstract: Silicon dioxide layers were formed by reacting silane with oxygen. The oxygen was ionized in an rf discharge chamber physically removed from the deposition zone. The excited oxygen species, which left the ionization chamber, reacted with silane regardless of the temperature, during deposition, to be chosen as an important parameter and at the same time avoided the adverse effects of placing the sample within an rf discharge. MOS capacitors were formed on silicon substrates and their electrical properties were evaluated by capacitance‐voltage (C‐V) measurements. An analysis of the quasistatic C‐V data indicates a midgap density of surface states NSS = 2×1011 cm−2eV−1 for SiO2 layers deposited at 300 °C.
TL;DR: In this article, the vibrational loss spectrum from the as-polished surface showed two major losses near 160 meV, a major loss at 360 meV (CH3 stretch), and two minor losses at 520 and 720 meV.
Abstract: Low‐energy, high‐resolution electron energy loss spectroscopy has been used to identify the vibrational modes of hydrogen on the semiconducting diamond surface providing the first direct evidence that the (111) 1×1 surface is terminated by hydrogen. The vibrational loss spectrum from the ’’as‐polished’’ surface shows two major losses near 160 meV (CH3 deformation), a major loss at 360 meV (CH3 stretch), and two minor losses at 520 and 720 meV (combinations and overtones). All of these losses disappear from the spectrum after heating the sample to ∠1000 °C (which has been established by other experiments to be sufficient to reconstruct the surface to 2×2/2×1). The loss spectrum for the reconstructed surface is indicative of a two‐dimensional metallic state of the dangling‐bond surface states for clean diamond. Exposure of this reconstructed surface to atomic hydrogen results in a loss spectrum which is essentially identical to that for the as‐polished surface. Further verification that the loss spectrum re...
TL;DR: In this article, the growth and energy-band alignment of ZnSe and GaAs was studied using X-ray photoelectron spectroscopy, and the authors showed that substantial interface structure dependent contributions to ΔEv can occur at Ge-ZnSe(110) and Ga-As(110), respectively.
Abstract: X‐ray photoelectron spectroscopy was used to study the growth and energy‐band alignment of ZnSe–GaAs(110) and ZnSe–Ge(110) heterojunctions. The ZnSe–GaAs heterojunctions were formed by growing ZnSe on GaAs(110). Growth temperatures were varied to produce both epitaxial and nonepitaxial interfaces. For ZnSe grown at ∠300 °C on GaAs(110), the valence‐ band discontinuity ΔEv was 0.96 eV; for ZnSe deposited at room temperature and crystallized at ∠300 °C, ΔEv is 1.10 eV. The Ge–ZnSe(110) interfaces were formed by depositing Ge(ZnSe) on ZnSe(Ge)(110) at room temperature, followed by ∠300 °C crystallization. The corresponding ΔEv’s were 1.52 and 1.29 eV, respectively. Our measured ΔEv values for epitaxial heterojunctions are compared with the predictions of theoretical models. Our results demonstrate that substantial interface structure dependent contributions to ΔEv can occur at Ge–ZnSe(110) and GaAs– ZnSe(110) heterojunctions.
TL;DR: In this paper, a binary compound with two different atoms per primitive cell is grown on a lattice matched elementary substrate in which the two atoms are identical, and there exists an inherent ambiguity in the nucleation of the compound, distinguished by an interchange of the two sublattices.
Abstract: When a binary compound with two different atoms per primitive cell is grown on a lattice‐ matched elementary substrate in which the two atoms are identical, there exists an inherent ambiguity in the nucleation of the compound, with two different possible atomic arrangements, distinguished by an interchange of the two sublattices of the compound. For defect‐free growth, one of the two possible nucleation modes must be suppressed. The problems involved in doing so depend very strongly on the crystallographic orientation of the substrate; for most orientations they are greatly complicated by the additional problem of electrical neutrality at the resulting polar/nonpolar interface. For zincblende‐on‐diamond growth, the (211) orientation is potentially one of the most promising orientations to overcome both classes of problems. The simplest possible atomic configuration for this orientation exhibits two different classes of bonding sites, some with one dangling bond, some with two, in the correct arrangement to create a strong preference for one of the two atomic configurations. We have grown GaP on Si (211) by MBE. Etching studies have indicated that (under the proper nucleation conditions) the growth is largely free of antiphase disorder, and that the sublattice ordering corresponds to P‐atoms bonded to those interface sites that have two back bonds to Si. The likely nucleation sequence is discussed.
TL;DR: In this paper, a simple chemically enhanced sputtering model is proposed to account for the main features of ion-induced etching, such as chemical identity of bombarding ions, flux of ions and neutrals to a surface, and ejection of products from a surface.
Abstract: Fundamental aspects of plasma‐assisted etching processes can be investigated in a well‐defined and controllable manner by ion‐beam techniques. We review here our experiments aimed at simulating a plasma environment using beams to investigate the effects of a number of fundamental parameters of plasma processes, such as the chemical identity of bombarding ions, flux of ions and neutrals to a surface, and ejection of products from a surface. Enhanced ion etching due to reactions of neutral gases with surfaces is demonstrated, and product ejection mechanisms are shown to be possible rate limiting factors in reactive etching processes. A simple chemically enhanced sputtering model suffices to account for the main features of ion‐induced etching. Applications of this model to bulk plasma processes, dependence of etch yield on ion angle of incidence, and surface composition modification are suggested.
TL;DR: In this article, the color of titanium nitride films deposited by reactive dc magnetron sputtering has been investigated as a function of elemental composition obtained by Auger analysis, and various colors obtained are specified in terms of dominant wavelength, purity, and brightness from results obtained by spectrophotometric measurements.
Abstract: The color of titanium nitride films deposited by reactive dc magnetron sputtering has been investigated as a function of elemental composition obtained by Auger analysis. At an average target current density of 44 mA cm−2 the nitrogen flow rate was varied from 0.02 Pa m2 s−1 to 0.06 Pa m2s−1 while argon flow was fixed such that a flow rate of 0.11 Pa m3s−1 resulted in a system pressure of 1.33 Pa. Hence average film growth rates at the substrate plane 4.75 cm away varied from 3000 A/min to 600 A/min as the target surface changed from titanium to titanium nitride. The various colors obtained are specified in terms of dominant wavelength, purity, and brightness from results obtained by spectrophotometric measurements. The values are compared with sputtered 18 kt gold. It is found that changes in elemental composition as a result of incorporation of background reactive gases other than nitrogen as the metal sputtering rate and substrate bias is changed, has a profound effect on color and also on other proper...
TL;DR: In this paper, a systematic study of the correlation between the core and valence level X-ray photo-emission spectra has been conducted, where the nature of chemical bonding and charge redistribution for bulk transition metal silicides has been examined.
Abstract: Via a systematic study of the correlation between the core and valence level X-ray photoemission spectra, the nature of the chemical bonding and charge redistribution for bulk transition metal silicides has been examined. Particular emphasis is placed on Pt2Si and PtSi. It is observed that the strength of the metal (d)-silicon (p) interaction increases in the order Ni2Si, Pd2Si, Pt2Si. It is also observed that both the metal and silicon core lines shift to higher binding energy as the silicides are formed. The notion of charge redistribution for metallic bonds is invoked to explain these data.
TL;DR: In this article, a sensitive probe of the oxide interfacial region, capable of locating and detecting as few as 1010 cm−2 positive states was presented, which is consistent with the mechanism of breaking strained Si-O-Si bonds near the interface, observed in x-ray photoelectron spectroscopy experiments.
Abstract: In previous work, we have established that thin oxide (40–50 A) MOS structures exhibit, prior to large levels of Fowler–Nordheim injection, the ideal tunneling behavior of a uniform trapezoidal barrier with thick oxide properties With increasing levels of electron injection towards the Si/SiO2 interface (up to 6×1018 e/cm2), a build‐up of excess current results This behavior is shown to be due to the generation of positive states in the SiO2 about 14 A from the Si/SiO2 interface, giving excellent agreement with our analysis of charge‐assisted tunneling The approach is seen to offer a sensitive probe of the oxide interfacial region, capable of locating and detecting as few as 1010 cm−2 positive states Comparisons are made among three oxidation processes, revealing wet oxides to be more susceptible than dry oxides to the state generation process The results are consistent with the mechanism of breaking strained Si–O–Si bonds near the interface, observed in x‐ray photoelectron spectroscopy experiments
TL;DR: In this article, a correlation between the electronegativity of the impurity atom and its catalytic poisoning ability was found. But, the correlation was not shown to hold for all impurity atoms.
Abstract: Recent work has demonstrated the special advantages of meshing in a single apparatus kinetic measurements at process‐like conditions with modern surface analytical techniques for fundamental catalytic studies. These data have shown that low surface area monolithic materials can be used successfully to model certain catalytic systems. Virtually identical kinetic parameters have been found for the methanation reaction over single crystals of nickel and ruthenium as have been measured for high surface area nickel and ruthenium process catalysts. Surface probes have allowed the methanation reaction to be mechanistically dissected, in that the kinetics associated with the two major reaction steps have been individually measured. Using surface probes to monitor quantity and ordering of the impurity atoms, a correlation has been found between the electronegativity of the impurity atom and its catalytic poisoning ability. Electronic effects, as opposed to site blocking, are shown to dominate.
TL;DR: In this article, the fundamental processes involved in laserenhanced gas-surface chemistry with particular emphases on aspects directly related to chemical etching of solids are discussed, i.e., adsorption, product formation, and desorption affected by the presence of the laser radiation field.
Abstract: Chemical reactions in homogeneous systems activated by laser radiation have been extensively investigated for many years. The applications of lasers to promote gas–surface interactions have just begun to be realized. The purpose of the paper is to examine the fundamental processes involved in laser‐enhanced gas–surface chemistry with particular emphases on aspects directly related to chemical etching of solids. Specifically, three basic surface processes, i.e., adsorption, product formation, and desorption affected by the presence of the laser radiation field, are discussed. Current studies on laser‐induced chemical etching including etch rates, spatial resolution, directionality, and selectivity are reviewed. Examples to illustrate the basic laser‐stimulated processes and possible applications of the laser technique to material processing are also given.
TL;DR: In this paper, the effect of annealing on the strength of the diamond-metal interface was investigated by measuring the static friction force of an atomically clean metal sphere on a diamond flat in ultrahigh vacuum.
Abstract: Recent electron spectroscopic investigations have shown that the diamond surface undergoes a transformation in its electronic structure by a vacuum anneal at ∠900 °C. The polished surface has no electronic states in the band gap, whereas the annealed surface has both occupied and unoccupied states in the band gap. In addition, the annealed surface exhibits some electrical conductivity. The effect of this transformation on the strength of the diamond–metal interface is investigated by measuring the static friction force of an atomically clean metal sphere on a diamond flat in ultrahigh vacuum. The friction force is due to interfacial bonding. It is found that low friction (weak bonding) is associated with the diamond surface devoid of gap states whereas high friction (strong bonding) is associated with the diamond surface with gap states. Exposure of the annealed surface to excited hydrogen also leads to weak bonding. The interfacial bond will be discussed in terms of interaction of the metal conduction band electrons with the band gap states on the diamond surface. Effects of surface electrical conductivity on the interfacial bond will also be considered.
TL;DR: In this paper, the relative density of Cl+2 in a chlorine radio frequency discharge as a function of pressure, flow, power, frequency, and distance from the electrodes was determined.
Abstract: Laser‐induced fluorescence has been used to determine the relative density of Cl+2 in a chlorine radio frequency discharge as a function of pressure, flow, power, frequency, and distance from the electrodes. The conditions studied correspond closely to those used in anisotropic plasma etching of materials such as Si and InP. This technique provides quantitative data on ion densities over a wide range of parameters, as contrasted with qualitative methods, such as optical emission.
TL;DR: In this paper, the effect of the X-ray flux on the constitution of polytetrafluoroethylene (PTFE) surface has been examined and the results are consistent with the development of a heavily cross-linked or branched structure in the PTFE surface region and the evolution of short chain fragments into the gas phase.
Abstract: The effect of the X-ray flux in X-ray photoelectron spectroscopy (STAT) on the constitution of the polytetrafluoroethylene (PTFE) surface has been examined. The radiation dose rate for our specimen was about 10 to the 7th rad/s. The structure, magnitude and binding energy of the C(1s) and F(1s) features of the XPS spectrum and the mass spectrum of gaseous species evolved during irradiation are observed. The strong time dependence of these signals over a period of several hours indicated that the surface constitution of PTFE is greatly affected by this level of radiation dose. The results are consistent with the development of a heavily cross-linked or branched structure in the PTFE surface region and the evolution of short chain fragments into the gas phase.
TL;DR: A summary of the current status of impurity-induced texturing, with emphasis on recent developments, can be found in this paper, where the texturing accompanying deposition of an impurity material onto a solid surface while simultaneously etching the surface with an ion beam is discussed.
Abstract: It is pointed out that the development of surface topography along with enhanced surface and bulk diffusion processes accompanying ion bombardment have generated growing interest among users of ion beams and plasmas for thin film or material processing. Interest in these processes stems both from attempts to generate topographic changes for specific studies or applications and from the need to suppress or control undesirable changes. The present investigation provides a summary of the current status of impurity-induced texturing, with emphasis on recent developments. Particular attention is given to the texturing accompanying deposition of an impurity material onto a solid surface while simultaneously etching the surface with an ion beam. A description of experimental considerations is provided, and a thermal-diffusion model is discussed along with the development of sputter cones, and aspects of impact-enhanced surface diffusion.
TL;DR: The literature currently abounds with experimental studies of Schottky barrier heights of various metals upon many semiconductors as mentioned in this paper, however, these studies present some puzzling aspects: (1) Commonly, barriers determined by C-V studies are larger than barrier determined by I−V studies, and (2) Results obtained by different workers under apparently identical conditions are not always similar.
Abstract: The literature currently abounds with experimental studies of Schottky barrier heights of various metals upon many semiconductors. Unfortunately, these studies present some puzzling aspects: (1) Commonly, barriers determined by C–V studies are larger than barriers determined by I–V studies, and (2) Results obtained by different workers under apparently identical conditions are not always similar. A possible explanation for such effects is simply that many/most contacts experimentally achieved are in fact multiphase; these different barrier‐height regions could result from variations in the metallurgical reactions assumed by many current models of Schottky barrier energetics. The different barrier heights measured by different techniques follow directly from the functional form of the relevant probes (e.g., I–V would more heavily weight a low‐barrier region). The lack of reproducibility would follow from kinetic aspects of the relevant metallurgical interactions. A recent publication discusses the function...