Deposition kinetics of silicon dioxide from tetraethylorthosilicate by PECVD

Tetraethylorthosilicate (TEOS)-based SiO2 films were prepared in an RF reac tor at various discharge powers and two substrate temperatures, and infra-r ed absorption spectra were taken for each deposited film using an FTIR spec trometer. Based on the FTIR observations, a model for the plasma and surfac e kinetics was developed. Using a proposed three-step reaction mechanism at the surface of a two-dimensional lattice, the growth rate of the films and the incorporation rate of Si-O-Si bridges into the films were derived as f unctions of the densities of the film precursors, oxygen atoms and molecula r oxygen ions. The densities are further given by the uniform discharge mod el of our previous work as a function of the discharge power. According to the model, in the regime of high ratio of oxygen to TEOS flow the growth ra te is governed by the film precursors generated from TEOS, and the incorpor ation rate is additionally determined by oxygen radicals and molecular oxyg en ions and by the dehydration process. The growth rate was measured in mu m/min and the relative incorporation rate was obtained from the absorption intensity of Si-O-Si rocking mode in FTIR spectra. The formulation of the m odel was compared with the experimental results, and on the validity of the model was discussed. (C) 2000 Elsevier Science S.A. All rights reserved.