Homogeneous and surface chemistry of the chemical vapor deposition of aluminosilicates from metal chloride mixtures in CO_2 and H_2

摘要

Detailed homogeneous and surface reaction mechanisms that describe the chemistry of the chemical vapor codeposition of silica, alumina, and aluminosilicates from mixtures of silicon tetrachloride or methyltrichlorosilane (MTS), aluminum trichloride, carbon dioxide and hydrogen are formulated. A detailed mechanism for the generation of H_2O, OH and other O-H species through the water-gas shift reaction is included in the homogeneous model. The predictions of the mathematical model are compared with experimental data obtained in our laboratory in a hot-wall CVD reactor of tubular geometry. The model is found to be capable of predicting most of the behavior patterns observed in the experiments, including those of the enhancement of the deposition rate of silica in the presence of AlCl_3 in the feed, the suppression of the incorporation rate of silica in the deposit in the presence of silane species in the feed, and the higher rate of codeposition and deposition rate of silica from MTS.