Stress Dependence of Oxidation Reaction at SiO2/Si Interfaces during Silicon Thermal Oxidation

Abstract

The microscopic processes of interfacial reaction of O2 molecules involving compressive stress normal to SiO2/Si(001) interface are investigated by first-principles total-energy calculations. It is found that the energy barrier height for the O2 reaction increases with residual stress at the interface. This is because the energy of the transition state structure for O2 diffusion before O2 insertion into the Si substrate is higher than that for the stress-free interface. The calculated activation volume (7.9 Å3) is comparable to those obtained by numerical simulations using experimental data, implying that the effects of interfacial stress on the reaction of O2 molecules play important roles during thermal oxidation of silicon nanostructures.