Chemical Vapor Deposition of Aluminosilicates from Mixtures of SiCl4, AlCl3, CO 2, and H 2

Abstract

A comprehensive study of the chemical vapor codeposition of silica, alumina, and aluminosilicates from mixtures is presented. A hot‐wall reactor, coupled to an electronic microbalance, is used to investigate the dependence of the deposition rate on temperature, pressure, composition, and total flow rate over a broad range of operating conditions. The experimental observations are discussed in the context of the results obtained in independent deposition experiments of silica and alumina from mixtures of and , respectively, in the same apparatus. The results show that the deposition of silica proceeds at very low rates that are by more than an order of magnitude lower than those of alumina deposition at the same temperature, pressure, total flow rate, and carbon dioxide and chloride mole fractions in the feed. When both chlorides ( and ) are fed to the reactor, that is, in the codeposition process, the rate of deposition is much higher than that seen in the single species deposition experiments, while the opposite behavior is observed for the rate of deposition of . The results of deposition experiments conducted on refractory wires, in order to obtain information on the effect of the substrate position in the reactor, show that manipulation of residence time offers a way to control the composition of the codeposited films in alumina and silica. The experimental results are compared with those obtained in a past study using methyltrichlorosilane as silicon source. © 2000 The Electrochemical Society. All rights reserved.