Showing papers in "Journal of Vacuum Science and Technology in 2000"
TL;DR: In this article, the authors review the advances in the development of plasma processes and plasmasystems for the synthesis of thin film high and low index optical materials, and in the control of plasma surface interactions leading to desired film microstructures.
Abstract: Plasma enhanced chemical vapor deposition(PECVD) is being increasingly used for the fabrication of transparent dielectric optical films and coatings. This involves single-layer, multilayer, graded index, and nanocomposite optical thin filmsystems for applications such as optical filters, antireflective coatings, optical waveguides, and others. Beside their basic optical properties (refractive index, extinction coefficient, optical loss), these systems very frequently offer other desirable “functional” characteristics. These include hardness, scratch, abrasion, and erosion resistance, improved adhesion to various technologically important substrate materials such as polymers, hydrophobicity or hydrophilicity, long-term chemical, thermal, and environmental stability, gas and vapor impermeability, and others. In the present article, we critically review the advances in the development of plasma processes and plasmasystems for the synthesis of thin film high and low index optical materials, and in the control of plasma–surface interactions leading to desired film microstructures. We particularly underline those specificities of PECVD, which distinguish it from other conventional techniques for producing optical films (mainly physical vapor deposition), such as fabrication of graded index (inhomogeneous) layers, control of interfaces, high deposition rate at low temperature, enhanced mechanical and other functional characteristics, and industrial scaleup. Advances in this field are illustrated by selected examples of PECVD of antireflective coatings, rugate filters, integrated optical devices, and others.
542 citations
TL;DR: The bulk of developmental work on transparent conducting oxides (TCOs) has been somewhat empirical as discussed by the authors, which applies both to more familiar materials such as indium tin oxide (ITO) and to less-well-known materials that have emerged in recent years.
Abstract: The bulk of developmental work on transparent conducting oxides (TCOs) has been somewhat empirical. This statement applies both to more familiar materials such as indium tin oxide (ITO) and to less-well-known materials that have emerged in recent years. In this article, we place a greater emphasis on more fundamental research. Our eventual goal is to gain a thorough understanding of these materials, their potential for further improvement, whether or not they suggest new and potentially superior materials, and the way their properties are influenced by structural and other issues. We also hope to provide guidelines to other researchers working in this area. We have investigated films of cadmium oxide (CdO), cadmium stannate (Cd2SnO4 or CTO), and zinc stannate [Zn2SnO4 (ZTO)]. The CdO was prepared by chemical-vapor deposition, whereas the stannates were prepared by rf sputtering. In both cases, Corning 7059 glass substrates were used. However, some depositions were also made onto tin oxide, which had a pro...
321 citations
TL;DR: In this article, a diamond-like carbon (DLC) film with a friction coefficient of 0.001 and wear rate of 10.9 to 10.10 mm{sup 3}/N.
Abstract: In this study, the authors introduce a new diamondlike carbon (DLC) film providing a friction coefficient of 0.001 and wear rates of 10{sup {minus}9} to 10{sup {minus}10} mm{sup 3}/N.m in inert-gas environments (e.g., dry nitrogen and argon). The film was grown on steel and sapphire substrates in a plasma enhanced chemical vapor deposition system that uses using a hydrogen-rich plasma. Employing a combination of surface and structure analytical techniques, they explored the structural chemistry of the resultant DLC films and correlated these findings with the friction and wear mechanisms of the films. The results of tribological tests under a 10-N load (creating initial peak Hertz pressures of 1 and 2.2 GPa on steel and sapphire test pairs, respectively) and at 0.2 to 0.5 m/s sliding velocities indicated that a close correlation exists between the friction and wear coefficients of DLC films and the source gas chemistry. Specifically, films grown in source gases with higher hydrogen-to-carbon ratios had the lowest fiction coefficients and the highest wear resistance. The lowest friction coefficient (0.001) was achieved with a film on sapphire substrates produced in a gas discharge plasma consisting of 25% methane and 75% hydrogen.
318 citations
TL;DR: In this paper, a novel high power density pulsed plasma discharge is presented, which consists of metallic and inert gas ions, determined from time resolved Langmuir probe measurements and in situ optical emission spectroscopy data.
Abstract: Time resolved plasma probe measurements of a novel high power density pulsed plasma discharge are presented. Extreme peak power densities in the pulse (on the order of several kW cm−2) result in a very dense plasma with substrate ionic flux densities of up to 1 A cm−2 at source-to-substrate distances of several cm and at a pressure of 0.13 Pa (1 mTorr). The pulse duration was ∼100 μs with a pulse repetition frequency of 50 Hz. The plasma consists of metallic and inert gas ions, as determined from time resolved Langmuir probe measurements and in situ optical emission spectroscopy data. It was found that the plasma composition at the beginning of the pulse was dominated by Ar ions. As time elapsed metal ions were detected and finally dominated the ion composition. The effect of the process parameters on the temporal development of the ionic fluxes is discussed. The ionized portion of the sputtered metal flux was found to have an average velocity of 2500 m s−1 at 6 cm distance from the source, which conforms...
279 citations
TL;DR: In this paper, the authors present a model for gas permeation through defects in barrier coatings, which is based on a very simple geometrical approach, and they compare with published data for aluminized PET.
Abstract: We begin this article by presenting a model for gas permeation through defects in barrier coatings, which is based on a very simple geometrical approach. This model allows us to evaluate permeation through a single- or through multiple circular defects in the coating, and also in special cases of size distributions and noncircular geometries. The model agrees well with published results based on complex computer simulations, and it has proven very useful in the analysis of our permeation measurements for barrier-coated plastic films. We then present correlations between measured O2 transmission rate (OTR) values and the number densities and size distributions of defects in SiO2 and SiN barrier coatings on polyester (PET), results which we compare with published data for aluminized PET. We also show the temperature dependence of OTR and H2O vapor transmission rate for SiO2 and SiN coatings deposited on one and on both sides of PET films. The apparent activation energies evaluated from these measurements su...
253 citations
TL;DR: Sculptured thin films (STFs) are a new class of engineered columnar thin films in which their shapes can resemble oblique matchsticks, chevrons, multiple zigzags, S’s, C's, helices, and even superhelices as mentioned in this paper.
Abstract: Sculptured thin films (STFs) are a new class of engineered columnar thin films in which their shapes can resemble oblique matchsticks, chevrons, multiple zigzags, S’s, C’s, helices, and even superhelices. They can have densities as low as 10%–30% of the bulk material and can be made of virtually any material. The origin and evolution of columnar thin films are reviewed in the context of structure zone models in which both thermally induced and ion bombardment-induced adatom mobility effects are considered. Since STFs are prepared under low adatom mobility and oblique angle of vapor incidence conditions, the columns are the result of clustering at the 1–10 nm level, with atomic self-shadowing controlling their growth evolution. The distribution functions of the cluster sizes, shapes, and relative heights are shown to be critical for any quantitative understanding of columnar growth, especially for achieving and maintaining steady state column diameters for oblique incidence where the self-shadowing is anisotropic in the plane of the film.
248 citations
TL;DR: In this paper, a low-k Si-O-C-H composite film was prepared using bis-trimethylsilylmethane as a precursor and oxygen in a rf plasma reactor.
Abstract: Low-k Si–O–C–H composite films were prepared using bis-trimethylsilylmethane as a precursor and oxygen in a rf plasma reactor. The growth rate of the Si–O–C–H composite film followed a second-order exponential decay function. This behavior could be explained by the formation of nanosized voids due to Si–CH3 and OH-related bonds included in the film. OH-related bonds were detected in films deposited at 30 °C, but could not be observed for the films deposited above 60 °C. In contrast, Si–CH3 bonds were also detected at 30 °C, but decreased monotonically up to 210 °C and were absent of higher temperatures. After postannealing the film deposited at 30 °C, the Si–CH3 bonds were unchanged, but the OH-related bonds were easily removed. This film showed a low dielectric constant of 2.44 and leakage current density of 4.4×10−7 A/cm2 at 1 MV/cm.
121 citations
TL;DR: The Boltzmann transport equation can be solved to give analytical solutions to the resistivity, Hall, Seebeck, and Nernst coefficients as mentioned in this paper, which may be solved simultaneously to give the density-of-states (DOS) effective mass, the Fermi energy relative to either the conduction or valence band, and a scattering parameter that is related to a relaxation time and the Fermani energy.
Abstract: The Boltzmann transport equation can be solved to give analytical solutions to the resistivity, Hall, Seebeck, and Nernst coefficients These solutions may be solved simultaneously to give the density-of-states (DOS) effective mass, the Fermi energy relative to either the conduction or valence band, and a scattering parameter that is related to a relaxation time and the Fermi energy The Nernst coefficient is essential for determining the scattering parameter and, thereby, the effective scattering mechanism(s) The authors constructed equipment to measure these four transport coefficients simultaneously over a temperature range of 30-350 K for thin, semiconducting films deposited on insulating substrates
120 citations
TL;DR: Baselt et al. as discussed by the authors examined the theoretical signal to noise ratio of this type of assay for the special case of a single magnetic bead being detected by a single giant magnetoresistive (GMR) detector.
Abstract: Commercially available superparamagnetic nanospheres are commonly used in a wide range of biological applications, particularly in magnetically assisted separations. A new and potentially significant technology involves the use of these particles as labels in magnetoresistive assay applications. In these assays, magnetic bead labels are used like fluorescent labels except that the beads are excited and detected with magnetic fields rather than with photons. A major advantage of this technique is that the means for excitation and detection are easily integrable on a silicon circuit. A preliminary study of this technique demonstrated its basic feasibility, and projected a sensitivity of better than 10−12 molar [Baselt et al., Biosensors Bioelectronic 13, 731 (1998)]. In this article we examine the theoretical signal to noise ratio of this type of assay for the special case of a single magnetic bead being detected by a single giant magnetoresistive (GMR) detector. Assuming experimentally observed and reasona...
119 citations
TL;DR: In this paper, a low photon energy-pass filter has been designed and built, ensuring a high spectral purity on the vacuum ultraviolet (VUV) SU5 beamline at Super-ACO.
Abstract: In order to separate the fundamental synchrotron radiation from the high harmonics emitted by an undulator, a low photon energy-pass filter has been designed and built, ensuring a high spectral purity on the vacuum ultraviolet (VUV) SU5 beamline at Super-ACO. It consists of an absorption cell filled with rare gases and separated from the ultrahigh vacuum of the storage ring and of the beamline by a double differential pumping obtained with thin capillaries. Its conception has been optimized by numerical computation of pumping speed. Admission pressures in the range of 100 Pa in the central part of the filter have been used without any degradation of the upstream or downstream ultrahigh vacuum. The measured attenuation factors above the energy cutoff are above 105 and 102 (and certainly above 103 with ultimate pressure of Ne) for argon and neon absorbing gases, respectively, with no measurable attenuation of fundamental radiation. A sophisticated numerical simulation of the pressure distribution, taking in...
119 citations
TL;DR: In this paper, a low-pressure high density plasma reactor working with a cryogenic chuck has been used for anisotropic etching of silicon structures with high selectivity towards the SiO2 mask.
Abstract: Deep and narrow anisotropic etching of silicon structures has been investigated in a low-pressure high density plasma reactor working with a cryogenic chuck. We have previously demonstrated the feasibility of this technique on such structures. Improvement of etch rate and profiles has been studied and new results show 2 μm wide trenches etched to a depth of 50 μm at an average etch rate of 5 μm/min with highly anisotropic profiles and very high selectivity (>500:1) toward the SiO2 mask. An evaluation of a commercially available reactor from Alcatel has been carried out and similar results are obtained. A phosphosilicate glass mask has been used to study the effect on profiles. It is shown that undercut is reduced while bowing is independent of the mask material. Since surface temperature strongly affects the profiles, wafer deformations in our cryogenic chuck have been measured and temperature evolution across the wafer has been estimated. A significant temperature difference of 10 °C between the chuck an...
TL;DR: In this paper, a systematic study of the Mn 2p, 3s, and 3p core-level photoemission and satellite structures for Mn model compounds was performed and the results were best understood in terms of the configuration-interaction model including intrashell electron correlation, charge transfer, and final-state screening.
Abstract: We report a systematic study of the Mn 2p, 3s, and 3p core-level photoemission and satellite structures for Mn model compounds. Charge transfer from the ligand state to the 3d metal state is observed and is distinguished by prominent shake-up satellites. We also observe that the Mn 3s multiplet splitting becomes smaller as the Mn oxidation state increases, and that 3s–3d electron correlation reduces the branching ratio of the 7S:5S states in the Mn 3s spectra. In addition, as the ligand electronegativity decreases, the spin-state purity is lost in the 3s spectra, as evidenced by peak broadening. Our results are best understood in terms of the configuration–interaction model including intrashell electron correlation, charge transfer, and final-state screening.
TL;DR: In this article, the role of pulse frequency, duty cycle, and reverse voltage in the deposition process of reactive pulsed dc magnetron sputtering has been investigated, and the optimum conditions for the production of high-quality alumina films under hard arc-free conditions were also identified.
Abstract: The pulsed magnetron sputtering (PMS) process is now among the leading techniques for the deposition of oxide films. In particular, the use of pulsed dc power has transformed the deposition of dielectric materials, such as alumina. The periodic target voltage reversals during the PMS process effectively discharge poisoned regions on the target. This significantly reduces the occurrence of arc events at the target and stabilizes the deposition process. Many researchers have now shown that pulsed dc reactive magnetron sputtering can be routinely used to produce fully dense, defect-free oxide films. Despite the success of the PMS process, few detailed studies have been carried out on the role played by parameters such as pulse frequency, duty cycle, and reverse voltage in the deposition process. In this study, therefore, alumina films were deposited by reactive pulsed dc magnetron sputtering. Operating conditions were systematically varied and the deposition process monitored throughout. The aim was to investigate the influence of the pulse parameters on the deposition process, and the interrelationships between the occurrence of arc events and the parameters chosen. As a result of this investigation, optimum conditions for the production of high-quality alumina films under hard arc-free conditions were also identified.
TL;DR: In this paper, the authors compared the performance of inductively-coupled plasma high-density plasma chemical vapor deposition (HDP CVD), plasma-enhanced chemical vapor (PECVD), and low pressure chemical vaporization (LPCVD) methods.
Abstract: Silicon nitride films have been deposited using inductively-coupled plasma high-density plasma chemical vapor deposition (HDP CVD), plasma-enhanced chemical vapor deposition (PECVD), and low pressure chemical vapor deposition (LPCVD) methods. Characterization and comparison of the three films were performed using Fourier-transform infrared spectroscopy, secondary-ion mass spectroscopy, Rutherford backscattering spectrometry, and hydrogen forward-scattering spectrometry, in addition to wet-etch rate and stress measurement studies. It was found that silicon nitride films deposited using HDP CVD method have several advantages over the silicon nitride films that were deposited using the LPCVD and PECVD methods. The HDP CVD silicon nitride film can be deposited at much lower temperatures (⩽400 °C) than LPCVD silicon nitride, and has substantially less hydrogen (5.5 at. %) than the PECVD film. In addition, the PECVD film contains some oxygen in the film. The wet-etch rate of HDP CVD silicon nitride film is comp...
TL;DR: Robbie et al. as mentioned in this paper fabricated periodic arrays of cobalt posts with a regular elemental period of 600 nm and post diameters and heights of 300 and 400 nm, respectively.
Abstract: An advanced deposition technique known as glancing angle deposition (GLAD) [K. Robbie, J. C. Sit, and M. J. Brett, J. Vac. Sci. Technol. B 16, 1115 (1998); K. Robbie and M. J. Brett, U.S. Patent No. 5,866,204 (filed 1999)] has been used to fabricate periodic arrays of magnetic pillars and randomly seeded magnetic helices, posts, and chevrons. Because of the nature of initial film nucleation, the GLAD process normally distributes posts randomly on the substrate surface. We can grow periodic arrays of GLAD microstructures by suppressing the randomness inherent within the initial nucleation stage of film growth. Shadowing sites were fabricated by pre-patterning a thin titanium layer on silicon substrates into a square array using electron beam lithography. These sites shadow regions of the substrate from incident flux during film deposition and act as preferred nucleation sites for film growth. Using this process, we have fabricated periodic arrays of cobalt posts with a regular elemental period of 600 nm and post diameters and heights of 300 and 400 nm, respectively. Randomly seeded posts, helices, and chevrons were also fabricated. The mean separation for the randomly seeded posts was 350 nm with individual post diameters of 100–150 nm, while the separations for the helices and chevrons were less than 100 nm. X-ray diffraction, transmission electron microscopy, and a dc superconducting quantum interference device magnetometer were used to analyze the magnetic and crystal properties of both the periodic and randomly seeded arrays. A newly developed three-dimensional ballistic deposition simulator was used to simulate the growth of the periodic post arrays in order to better understand the growth mechanisms.
TL;DR: In this paper, an ionization fraction of over 10% and an electron temperature of the order of 1 eV for the sputtered material was found for the magnetron sputtering of titanium by argon at pressures between 0.5 and 100 Pa.
Abstract: Emission spectra in the visible and near ultraviolet have been recorded for the magnetron sputtering of titanium by argon at pressures between 0.5 and 100 Pa. Intense emission lines from both atomic and ionic material were detected, and comparison of line intensities yielded an ionization fraction of over 10% and an electron temperature of the order of 1 eV for the sputtered material. The ionization fraction decreased with increasing magnetron power, and an optimal operating pressure was found for maximum ion content of the sputtered flux. Scaling laws of emission line intensity with magnetron power indicated the incomplete thermalization of sputtered metal with the sputtering plasma, and spatially resolved measurements of ionization profiles were used to investigate the transport and collisional ionization of sputtered material. Penning ionization of sputtered titanium by metastable argon was found to be the dominant ionization process, and the effect of diffusion of metastable argon was noted. Control of ion content in sputtered fluxes is of interest for the deposition of thin films and for metallization of semiconductors.
TL;DR: In this paper, an external solenoid was used to form a magnetic trap between the target and the substrate, and the influence of substrate temperature, substrate bias and the magnetic trap on film growth and properties was studied by different surface and thin-film analysis techniques and electrical measurements.
Abstract: Aluminum oxide films were grown by reactive magnetron sputtering. In order to maintain a stable deposition process and high deposition rate, a pulsed direct current bias was applied to the aluminum target and the substrate. An external solenoid was used to form a magnetic trap between the target and the substrate. The influence of substrate temperature, substrate bias, and the magnetic trap on film growth and properties was studied by different surface and thin-film analysis techniques and electrical measurements. Normally, amorphous alumina films were produced. However, under optimum process conditions, crystalline alumina films can be obtained at temperatures as low as 250 °C, with a hardness ∼20 GPa and excellent electrical insulating properties.
TL;DR: In this article, the amplitude of periodic nanoscale ripple patterns formed on Ar+ sputtered Si(OOl ) surfaces was examined using a recently developed in situ spectroscopic technique.
Abstract: The time evolution of the amplitude of periodic nanoscale ripple patterns formed on Ar+ sputtered Si(OOl ) surfaces was examined using a recently developed in situ spectroscopic technique. At sufficiently long times, we find that the amplitude does not continue to grow exponentially as predicted by the standard Bradley-Harper sputter rippling model. In accounting for this discrepancy, we rule out effects related to the concentration of mobile species, high surface curvature, surface energy anisotropy, and ion-surface interactions. We observe that for all wavelengths the amplitude ceases to grow when the width of the topmost terrace of the ripples is reduced to approximately 25 nm. This observation suggests that a short circuit relaxation mechanism limits amplitude . growth. A strategy for influencing the ultimate ripple amplitude is discussed.
TL;DR: In this paper, the authors investigated the assumption that the extraction efficiency of ions produced by direct ionization of radicals and dissociative ionisation of the parent molecule used as the reference signal, are equal in the ionizer of the mass spectrometer.
Abstract: Appearance potential mass spectrometry (APMS) has recently gained importance for detection and quantitative measurements of reactive radical species in plasmas using line-of-sight sampling of radicals. In this work, we have investigated the assumption that the extraction efficiency of ions produced by direct ionization of radicals, and ions produced by dissociative ionization of the parent molecule used as the reference signal, are equal in the ionizer of the mass spectrometer. We find that the dissociative ionization products are extracted with much lower efficiency (2–50 times smaller for the cases studied) than the direct ionization products. This is expected due to the excess kinetic energy of the dissociatively ionized products as a result of the Franck–Condon effect. Use of this procedure will thus lead to an overestimation of the radical number density by a factor of 2–50, depending on the nature of the parent and the daughter ion. We recommend an alternate procedure for APMS that utilizes an inert...
TL;DR: In this article, the influence of the growth conditions, namely deposition pressure, rf power, Ar/N2 ratio, and substrate temperature, on polycrystalline AlN films has been systematically studied.
Abstract: Nucleation and growth of polycrystalline AlN films on thermal and chemical vapor deposited oxide have been studied during rf reactive sputter deposition. The influence of the growth conditions, namely deposition pressure, rf power, Ar/N2 ratio, and substrate temperature, on film properties has been systematically studied. The properties of interest are crystallinity, degree of orientation, crystallite size, surface roughness, stress, piezoelectric coupling, acoustic velocity, and others. The films have been analyzed with Rutherford backscattering spectroscopy, electron spectroscopy for chemical analysis, x-ray diffraction (XRD), ellipsometry, scanning electron microscopy, atomic force microscopy, stress measurements, etc. It is found that these properties are sensitive functions of all deposition parameters and that there exist optimal deposition conditions under which films of high quality are obtained. The films at optimal conditions were analyzed with the following results: full width half maximum (FWH...
TL;DR: In this paper, the authors demonstrate the successful fabrication of an almost defect free Si(001) surface by refining the standard annealing and flashing surface preparation method, which can reduce the defect density significantly.
Abstract: We demonstrate the successful fabrication of an almost defect free Si(001) surface by refining the standard annealing and flashing surface preparation method. On any desired samples, we can routinely fabricate a surface with defect densities lower than 0.1%, significantly reducing the defect density compared to surfaces fabricated by standard methodology.
TL;DR: In this paper, the authors investigated the electrical properties of Al-doped ZnO (AZO) films prepared by magnetron sputtering and found that the minimum obtained resistivity was roughly the same: 3.4×4×10−4 4.4 cm on substrates at 200°C.
Abstract: The origin of electrical property distribution on the substrate surface of Al-doped ZnO (AZO) films prepared by magnetron sputtering is reported. When the films were prepared on substrates at the same temperature with the same deposition rate under optimized sputter deposition and target preparation conditions, the minimum obtained resistivity found in AZO films prepared by either dc or rf magnetron sputtering was roughly the same: 3–4×10−4 Ω cm on substrates at 200 °C. However, the AZO films prepared by dc sputtering exhibited a larger increase of resistivity at locations on the substrate corresponding to the target erosion area than that found in films prepared by rf sputtering. The resistivity distribution of AZO films prepared by rf magnetron sputtering under an applied external magnetic field which focused the rf plasma was similar to that of films prepared by dc magnetron sputtering. Thus, the electrical property distribution found in films prepared by either dc or rf magnetron sputtering is mainly ...
TL;DR: In this paper, a series of physical-vapor deposition ceramic hard coatings (CrN/NbN, CrN, NbN and TiAlN/VN) using a ball-on-disk sliding configuration against corundum was studied.
Abstract: In order to address the important interest in wear debris and associated wear mechanisms, we have studied a series of physical-vapor deposition ceramic hard coatings (CrN/NbN, CrN, NbN, TiAlN/VN, and TiCN) using a ball-on-disk sliding configuration against corundum. The debris generated were characterized using Raman microscopy to identify compounds, especially oxides, generated during the wear process to gain a better understanding of tribochemical reactions. The high spatial resolution (2 μm), sensitivity to structural changes, and nondestructive nature make this technique ideal for the study of such small amounts of wear debris. This article examines binary, multicomponent, multilayered, and superlattice coatings. Under dry sliding conditions of 5 N normal load and 10 cm/s speed, titanium-based alloy coatings were found to provide TiO2 (rutile) debris. However, the addition of thin layers of VN to the TiAlN system provided a lower friction coefficient, and much less debris through the possible formatio...
TL;DR: In this paper, a thin-film, proton exchange membrane fuel cell was developed using photolithographic patterning, physical vapor deposition, and spin-cast deposition techniques, and the morphology desired for both the anode and cathode layers facilitates generation of maximum current density from the fuel cell.
Abstract: Thin-film, proton exchange membrane fuel cells are developed using photolithographic patterning, physical vapor deposition, and spin-cast deposition techniques. In this study, micrometer-thick layers of nickel (Ni) and platinum (Pt) electrodes, as well as the proton conducting electrolyte layer of perfluoronated sulfonic acid, are synthesized. The anode layer is conductive to pass the electric current and provides mechanical support to the electrolyte and cathode layer that enables combination of the reactive gases. The morphology desired for both the anode and cathode layers facilitates generation of maximum current density from the fuel cell. For these purposes, the parameters of the deposition process and post-deposition patterning are optimized for continuous porosity across both electrode layers. The power output generated through current–voltage measurement is characterized at various temperatures in the range of 60–90 °C using dilute (4%) hydrogen fuel.
TL;DR: Fluorinated amorphous-carbon films (a-C:F:H) were deposited by low-power rf capacitively coupled plasma-enhanced chemical-vapor deposition using CH4-CF4 gas mixtures as discussed by the authors.
Abstract: Fluorinated amorphous-carbon films (a-C:F:H) were deposited by low-power rf capacitively coupled plasma-enhanced chemical-vapor deposition using CH4–CF4 gas mixtures. Different series of films were deposited, changing one parameter at a time: the CF4 partial pressure from 0% to 100%, the self-bias voltage from −50 to −700 V, and the total deposition pressure from 5 to 15 Pa. The composition was determined by ion-beam analysis (IBA): Rutherford backscattering spectrometry, elastic recoil detection analysis, and nuclear reaction analysis. The atomic density of the films was evaluated by combining the IBA results with the thickness value measured by stylus profilometry. Film structure was investigated by infrared transmission and Raman scattering spectroscopies. The internal stress and Vickers hardness were also measured. For a fixed self-bias, the increase of the CF4 partial pressure leads to a higher fluorine incorporation and the decrease of both hardness and internal stress. The film microstructure chang...
TL;DR: In this article, the etch-induced damage of an inductively coupled plasma (ICP) etch system on the electrical performance of mesa-isolated GaN pn-junction diodes was investigated.
Abstract: Plasma-induced etch damage can degrade the electrical and optical performance of III-V nitride electronic and photonic devices. We have investigated the etch-induced damage of an Inductively Coupled Plasma (ICP) etch system on the electrical performance of mesa-isolated GaN pn-junction diodes. GaN p-i-n mesa diodes were formed by Cl{sub 2}/BCl{sub 3}/Ar ICP etching under different plasma conditions. The reverse leakage current in the mesa diodes showed a strong relationship to chamber pressure, ion energy, and plasma flux. Plasma induced damage was minimized at moderate flux conditions ({le} 500 W), pressures {ge}2 mTorr, and at ion energies below approximately -275 V.
TL;DR: In this article, a novel 3D ballistic deposition simulator 3D-FILMS is developed for the modeling of thin film deposition and structure, which features a ballistic transport algorithm to model incident species with angular distributions appropriate to physical vapor deposition systems.
Abstract: A novel three-dimensional (3D) ballistic deposition simulator 3D-FILMS has been developed for the modeling of thin film deposition and structure. The simulator features a ballistic transport algorithm to model incident species with angular distributions appropriate to physical vapor deposition systems. Two-tiered data structuring is employed in order to enable the simulator to run using memory resources available to workstations. The simulator has been applied to a unique class of thin films grown by the technique of glancing angle deposition (GLAD). These films exhibit low bulk density due to an internal structure consisting of isolated microcolumns, which can be engineered into a variety of 3D forms. Because of their inherent 3D morphology, created by a combination of complex substrate motion and 3D shadowing, GLAD films represent an ideal test subject for 3D simulation. Scanning electron microscope images of films are presented together with simulation results, which correctly reproduce aspects of colu...
TL;DR: In this paper, the microstructure of TiN was observed to be the columnar grain structure and the chemical species was analized by Auger electron spectroscopy (AES) and the Cl content in TiN film was detected below the detection limit of AES which was below 0.5%.
Abstract: TiN film was deposited on Si substrate by using an atomic layer chemical vapor deposition (CVD) system. In this system, the TiCl4 and NH3 gases were supplied, separately and Ar purge gas was added between the source and reactant gases to suppress the direct reaction. The microstructure of TiN was observed to be the columnar grain structure. The chemical species was analized by Auger electron spectroscopy (AES) and the Cl content in TiN film was detected below the detection limit of AES which was below 0.5%. The density of film grown at 450 °C measured by Rutherford backscattering spectroscopy was 4.85 g/cm3 and decreased as the process temperature decreased. The resistivity of this TiN was about 75 μΩ cm, which was very low compared to TiN film grown by other CVD methods. The step coverage of TiN film showed almost 100% conformality at 450 °C.
TL;DR: In this paper, the variation of the secondary electron yield (SEY) of sputter-cleaned oxygen-free highconductivity copper has been studied as a function of air exposure duration at room temperature.
Abstract: The variation of the secondary electron yield (SEY) of sputter-cleaned oxygen-free high-conductivity copper has been studied as a function of air exposure duration at room temperature. After short air exposures of some seconds the maximum SEY (δmax) of clean copper is reduced from 1.3 to less than 1.2, due to the oxidation of the copper surface. Prolonged air exposure increases the SEY steadily until, after about 8 days of atmospheric exposure, δmax is higher than 2. Air exposures at higher temperatures have been found to be effective in reducing the SEY of technical copper surfaces. A 5 min air exposure of copper at 350 °C followed by a 350 °C bakeout under vacuum reduces δmax to about 1.05, which is lower than the value of pure copper and that of Cu2O.
TL;DR: In this paper, the optimal energy conditions for ion impingement on growing CrN films with compact columnar crystal structure, high hardness, and enhanced tribological properties were studied with respect to the modulations of the bias voltages and the Cr/N ratios.
Abstract: Chromium nitride (CrN) films with Cr/N atomic ratios of 0.73–1.46 were prepared by reactive dc- magnetron sputtering with Ar as the sputtering gas and N2 as the reactive gas. The application of a negative bias voltage to the substrates and the decrement of the gas flow ratio of N2 to Ar (or FN2/FAr) promoted the growth of CrN films with preferred orientations of (200)+(220), high Cr/N ratios, and high densities. The functional hardness and compressive stress were highly dependent on the magnitude of the bias voltage and the Cr/N ratio that was adjusted by the FN2/FAr ratio during film deposition. The optimal energy conditions for ion impingement on growing CrN films with compact columnar crystal structure, high hardness, and enhanced tribological properties were studied with respect to the modulations of the bias voltages and the Cr/N ratios. The CrN films with high hardness and high wear resistance were synthesized in this study at low bias voltages of −(100–300) V and FN2/FAr ratios of 1–3.