Oxidation characteristics of silicon exposed to O(¹D₂) and O(³P₂) radicals and stress-relaxation oxidation model for O(¹D₂) radicals

Abstract

We investigated the oxidation of silicon by O(1D2) and O(3P2) radicals in a microwave plasma at 673 K in an Ar/O2 atmosphere containing a small amount of hydrogen. O(1D2) radical oxidation with hydrogen gave a much higher growth rate than wet thermal oxidation at 1223 K. The activation energies for the parabolic rate constant owing to O(1D2) and O(3P2) radical oxidations were respectively 0.18 and 0.40 eV, which are much lower than that (0.71 eV) by thermal oxidation. In time-dependent dielectric breakdown tests, despite SiO2 films formed by radicals having a higher degradation rate than those produced by thermal oxidation, SiO2 films formed by O(1D2) radicals had longer lifetimes. Our dielectric breakdown model indicates this is due to the flat SiO2 surface and interface suppressing two-dimensional local breakdown. A stress-relaxation oxidation model for O(1D2) radicals is proposed that well explains the formation of flat SiO2 surfaces and interfaces.