Some Properties of Vapor Deposited SiC

Abstract

A process for the vapor deposition of silicon carbide films on silicon substrates using the hydrogen reduction of silicon tetrachloride and the pyrolysis of a hydrocarbon such as toluene was developed. At the optimum deposition temperature of , the deposition rate using 0.89% silicon tetrachloride and 0.18% toluene was 1.6 µ/min. Films deposited at less than 0.18% toluene, with a fixed silicon tetrachloride concentration of 0.89%, were attacked by “Planar etch,” while those deposited at or above 0.18% toluene were not; the electrical resistance decreased, however. When the silicon tetrachloride concentration was varied from 0.7 to 0.9% at 0.18% toluene, the electrical resistance of the films was greater than one hundred megohms. The thermal coefficient of expansion was tailored to be less than, equal to, or greater than that of silicon by changing the concentration of silicon tetrachloride from 0.6 to 1.2% at 0.18% toluene. The refractive index of the films also changed with the change in silicon tetrachloride concentration. Infrared transmission data on films deposited at 0.18% toluene and 0.89% silicon tetrachloride were identical to those for bulk silicon carbide. X‐ray diffraction studies showed that the films were normally polycrystalline and consisted of both alpha and beta phases, however, epitaxial silicon carbide was observed in some cases.