Efficiency of the SiH 4 oxidation reaction in chemical vapour deposition of SiO 2 films at low temperature

Abstract

Our purpose in this paper is to evaluate the efficiency of the SiH 4 oxidation reaction in the heterogeneous low temperature chemical vapour deposition (CVD) of SiO 2 films onto wafers at atmospheric pressure in SiH 4-O 2-N 2 systems as a function of the CVD conditions. We obtained an increase-maximum-decrease type of dependence of the reaction efficiency on the [O 2]/[SiH 4] mole ratio with temperature as a parameter, in the temperature range 200–400°C. At a given [O 2]/[SiH 4] mole ratio the reaction efficiency increases with temperature. These results are qualitatively explained in terms of the bimolecular surface reaction theory and of the dependence of the film density on the CVD conditions. A reactor figure of merit is defined to compare the reaction efficiency on wafers for different CVD reactors.