Observation of Chemisorbed O2 Molecule at SiO2/Si(001) Interface During Si Dry Oxidation

Real-time X-ray photoemission spectroscopy was used to characterize the SiO2 surface, and SiO2/Si interface after irradiating n-Si(001) with a 0.06-eV supersonic O2 molecular beam. Molecularly-adsorbed O2 was observed not only during the Si surface oxidation process but also during the SiO2/Si interface oxidation process, suggesting that trapping-mediated adsorption occurs both at SiO2/Si interface and on the Si surface. We found an excellent linear correlation between the interface oxidation rate and the amount of molecularly-adsorbed O2, indicating that at room temperature, the double-step oxidation loop exclusively proceeds through Pb1-paul formation and minority carrier trapping. The offset of the linear correlation indicates the presence of ins-paul on the SiO2 surface, which has nothing to do with the double-step oxidation loop because point defect generation is not affected by the volume expansion of ins-paul oxidation in the flexible SiO2 network.