Chemically vapor deposited silicon carbide (CVD SiC) was oxidized at temperatures of 1000°-1400°C in H2O/O2 gas mixtures with compositions of 10-90 vol% water vapor at a total pressure of 1 atm. Additional experiments were conducted in H2O/argon mixtures at a temperature of 1100°C. Experiments were designed to minimize impurity and volatility effects, so that only intrinsic water-vapor effects were observed. The oxidation kinetics increased as the water-vapor content increased. The parabolic oxidation rates in the range of 10-90 vol% water vapor (the balance being oxygen) were approximately one order of magnitude higher than the rates that were observed in dry oxygen for temperatures of 1200°-1400°C. The power-law dependence of the parabolic oxidation rate on the partial pressure of water vapor at all temperatures of the study indicated that the molecular species was not the sole rate-limiting oxidant. The determination of an activation energy for diffusion was complicated by variations in the oxidation mechanism and oxide-scale morphology with the partial pressure of water vapor and the temperature.

Variation of the Oxidation Rate of Silicon Carbide with Water‐Vapor Pressure

The present paper is an analytical review of the last five or six years of research and development in SiC. It outlines the major achievements in single crystal growth and device technology. Electrical performance of SiC devices designed during these years and some new trends in SiC electronics are also discussed. During the 1980s the studies on sublimation and liquid-phase epitaxial growth of SiC single crystal were continued successfully. At that time, such methods as chemical vapour deposition, thermal oxidation, 'dry' plasma etching and ion implantation which yielded good results with silicon, came into use. As a result of the technological progress, discrete devices appeared, which incorporated the potential advantages of SiC as a wide bandgap material. Among these were high temperature (500-600 degrees C) rectifier diodes and field-effect transistors, high efficiency light-emitting diodes for the short-wave region of the visible spectrum, and detectors of ultraviolet radiation. It should be stressed that the devices were of commercial quality and could be applied in various fields (control systems of automobile engines, aerospace apparatus, geophysical equipment, colour displays in information systems, etc.). The developments in technology and the promising results of research on electrical performance of the devices already available give hope that in the near future SiC may become the basic material for power microwave devices, and for thermo- and radiation-resistant integrated circuits. This process can be stimulated by further perfection of single-crystal substrates of large area, by development of stable high temperature ohmic contacts, micro- and heterostructures.

https://iopscience.iop.org/article/10.1088/0268-1242/7/7/001/pdf

Recent developments in SiC single-crystal electronics

The invention comprises a method of etching silicon carbide targets. In one embodiment, a reactive ion plasma is formed from a gas which is easily dissociated into its elemental species in the plasma, for which all of the dissociated elemental species are volatile in the plasma, and for which at least one of the elemental species is reactive with silicon carbide. The silicon carbide target to be etched is positioned on one of the electrodes which is formed from a material with a low sputter yield and which material reacts with a dissociated species to thereby prevent contamination of the target with either sputtered materials from the electrode or polymerized species from the plasma.

Dry etching of silicon carbide

The oxidation kinetics of chemically vapor-deposited SiC in dry oxygen and wet oxygen (P(sub H2O) = 0.1 atm) at temperatures between 1200 C and 1400 C were monitored using thermogravimetric analysis. It was found that in a clean environment, 10% water vapor enhanced the oxidation kinetics of SiC only very slightly compared to rates found in dry oxygen. Oxidation kinetics were examined in terms of the Deal and Grove model for oxidation of silicon. It was found that in an environment containing even small amounts of impurities, such as high-purity Al2O3 reaction tubes containing 200 ppm Na, water vapor enhanced the transport of these impurities to the oxidation sample. Oxidation rates increased under these conditions presumably because of the formation of less protective sodium alumino-silicate scales.

Oxidation Kinetics of Chemically Vapor‐Deposited Silicon Carbide in Wet Oxygen

This silicon-carbide semiconductor device (101) has a silicon-carbide substrate (10), a main electrode (52), a first barrier layer (70a), and a wiring layer (60). The main electrode (52) is provided directly on top of the silicon-carbide substrate (10). The first barrier layer (70a) is provided on top of the main electrode (52) and is made from a conductive material that does not contain aluminum. The wiring layer (60) is provided on top of the first barrier layer (70a), is isolated from the main electrode (52) by the first barrier layer (70a), and is made from a material that does contain aluminum.

Silicon carbide semiconductor device

The physical properties and oxidation behavior of silicon carbide thin films are reported. These films were RF sputtered from a composite target of stoichiometric proportion onto thermally oxidized silicon substrates. The refractive index of the carbide films, after annealing at 1100°C in hydrogen, was very close to the bulk value of 2.65. Structural and compositional properties were studied by Rutherford backscattering spectrometry, secondary ion mass spectrometry, and x‐ray diffraction techniques. Thermal oxidation was carried out in wet and dry oxygen at 900°–1100°C for a period of up to 16h. Depending on the temperature and time period, the oxidation rate of silicon carbide was about 2–11 times slower than that of single‐crystal (100) Si. The oxide layer grown out of the carbide films was determined to be silicon oxide. The average activation energy for wet and dry oxidation was calculated to be 50 and 43.5 kcal/mol, respectively. The patterning of the films was investigated using and plasmas. "Bird's beak" profiles, obtained upon field oxidation of structures, were studied.

W. ‐J. Lu

Papers

Thermal Oxidation of Sputtered Silicon Carbide Thin Films