Study of the growth mechanisms of low-pressure chemically vapour deposited silica films

Abstract
We have studied the surface morphology evolution of SiO₂ films grown at 20 nm/min in a low-pressure chemical vapour deposition reactor from SiH₄/O₂ mixtures at low (611 K) and high (723 K) temperatures. Films have been deposited for times ranging from 10 min up to 48 hours. It is shown that the SiO₂ growth at high temperature becomes stable, whereas at low temperature it is unstable (i.e., the surface roughness increases continuously with deposition time). This clear difference is explained on the basis of the different growth mechanisms operating under both experimental conditions. These results are compared with the predictions of the few theoretical works on growth evolution by chemical vapour deposition.