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 dichlorod imethylsilane 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 an d 1.013 x 10(5) Pa (1 atm) pressure. Concentrations of silicon tetrach loride varied from 1 to 9 vol%. Gas chromatography was used to determi ne the volatile products of reaction, and gravimetric analysis was use d to determine the total silicon deposition on the tube. The model, ba sed on the experimental data, assumes the following reversible chemica l reactions: SiCl4 + H-2 double line arrow pointing left and right HSi Cl3 + HCl HSiCl3 + H-2 double line arrow pointing left and right H2SiC l2 + HCl H2SiCl2 double line arrow pointing left and right Si + 2HCI T he rate constants derived from a nonlinear regression analysis are rep orted.