Ultra-thin oxide growth on silicon during 10Â keV x-ray irradiation

Surface effects on silicon wafers irradiated by 10 keV x-rays at room temperature were characterized using x-ray photoelectron spectroscopy and spectroscopic ellipsometry. The samples were exposed to total ionizing doses ranging from 1.0 to 12 Mrad(SiO2) at x-ray dose rates ranging from 5.8 krad(SiO2)/min to 67 krad(SiO2)/min. Accelerated thin oxide growth on irradiated samples compared to natural native oxide growth under room temperature conditions was demonstrated, and the composition of the irradiation-accelerated oxide was investigated. The presence of suboxides along with silicon dioxide was confirmed on the irradiated silicon sample. Two thin oxide growth models were applied to characterize the enhanced oxidation rate observed for irradiated wafers.