MODEL FOR THE FORMATION OF SILICON-CARBIDE FROM THE PYROLYSIS OF DICHLORODIMETHYLSILANE IN HYDROGEN .1. SILICON FORMATION FROM CHLOROSILANES

Silicon tetrachloride is a major product of the pyrolysis of dichlorodimethylsilane in hydrogen. A model is developed for the deposition of silicon from the reduction of silicon tetrachloride with hydrogen in a tubular reactor at temperatures from 700-degrees to 1100-degrees-C and 1.013 x 10(5) Pa (1 atm) pressure. Concentrations of silicon tetrachloride varied from 1 to 9 vol%. Gas chromatography was used to determine the volatile products of reaction, and gravimetric analysis was used to determine the total silicon deposition on the tube. The model, based on the experimental data, assumes the following reversible chemical reactions: SiCl4 + H-2 double line arrow pointing left and right HSiCl3 + HCl HSiCl3 + H-2 double line arrow pointing left and right H2SiCl2 + HCl H2SiCl2 double line arrow pointing left and right Si + 2HCI The rate constants derived from a nonlinear regression analysis are reported.