Generation of excess Si species at Si∕SiO2 interface and their diffusion into SiO2 during Si thermal oxidation

Si self-diffusion in thermally grown SiO2 near the SiO2∕Si interface during thermal oxidation process was studied using isotopic heterostrucutures (SinatO2∕Si28) as a function of the oxidation temperature, the oxidation time, and the fraction of oxygen in the ambient gas. The Si self-diffusivity near the SiO2∕Si interface during oxidation was found to be larger than the thermal Si self-diffusivity by more than one order of magnitude. This enhancement indicates that Si species are emitted from the SiO2∕Si interface and diffused into SiO2 during oxidation, as has been predicted by recent theoretical studies.