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

• Published in: E-journal of surface science and nanotechnology Vol. 21; no. 1; pp. 30 - 39
• Main Authors: Tsuda, Yasutaka, Yoshigoe, Akitaka, Ogawa, Shuichi, Sakamoto, Tetsuya, Takakuwa, Yuji
• Format: Journal Article
• Language: English; Japanese
• Published: Tokyo The Japan Society of Vacuum and Surface Science 05.11.2022; Japan Science and Technology Agency
• Subjects: Interface oxidation; Minority carriers; Molecular beam; Molecular beams; Oxidation rate; Photoelectric emission; Point defects; Room temperature; Silicon; Silicon dioxide; Surface oxidation; Synchrotron radiation; Trapping
• ISSN: 1348-0391; 1348-0391
• DOI: 10.1380/ejssnt.2023-005

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.