Vapor deposition of silicon

Single crystal silicon deposits on a heated silicon substrate have been obtained from the reduction of trichlorosilane by hydrogen. Commercially available trichlorosilane can be Used without further purification to get n-type silicon deposits as high as 40 ohm cm. Surface preparation to get good epitaxy involves chemical etching followed by hydrogen reduction of native oxide immediately prior to introduction of HSiCl3, into the hydrogen flow. Good silicon deposition rates thus far encountered are optimal at 40-80 microns per hour, but can be increased by designing to minimize gas turbulence. Techniques of the process, including consideration of controlled doping will be discussed.