Chemical Kinetics of Silicon-Rich Oxide Growth in an LPCVD Reactor

Abstract

ABSTRACTThe chemical kinetics of Silicon Rich Oxide (SRO) growth in a N2O-SiH4 LPCVD reactor has been studied at deposition temperatures from 610 to 680°C and pressures from 0.4 to 0.5 torr. We can produce SRO films with a wide spectrum of input reactant ratios γ = [N2O]/[SiH4] = 1 to 40. The dependence of film composition on γ changes dramatically in a region around γ = 2.Growth for γ < 2 is consistent with the chemical kinetics of SIPOS growth. Growth for γ > 20 can be explained by oxidation of silicon in the bulk of the growing SRO film. We can explain growth from γ ≈ 4 to 20 by considering the chemical kinetics of possible binary surface reactions which may produce Si-Si or Si-O bonds. This allows us to accurately model the dependence of SRO growth rate in this region as a function of γ, pressure, and deposition temperature.