In situ secondary ion mass spectrometry study of the surface oxidation of silicon using 18O tracer

The formation and growth of SiO2, pertaining to normal incidence oxygen bombardment of silicon in secondary ion mass spectrometry analysis, has been studied using in situ implantation of 18O+ tracer. At the chosen energy of 15-keV O+, buried layer formation has been shown to occur prior to the formation of a continuous surface oxide layer. Supersaturation of oxygen within the oxide layer was found to give rise to a high oxygen mobility, with a diffusion coefficient of the order of 10−14 cm2/s, resulting in a large desorption flux at the front surface. From preferential sputtering considerations, the surface concentration was found to be close to that of SiO2.