| 研究実績の概要 |
The rapid temperature oxidation kinetics on Si(001) surfaces was investigated by real-time X-ray photoelectron spectroscopy (XPS) using synchrotron radiation to observe the SiO2 growth rate and interfacial strain simultaneously during oxidation. It was observed that the SiO2 growth rate was enhanced 5.0 times by cooling temperature. The SiO2 oxide growth kinetics is interpreted well by extending the unified Si oxidation reaction model, where oxide growth rate dRSiO2/dt is in proportion to the increase of the interfacial strain. This implies that further oxidation is prone to occur around the place where oxides are newly grown at low temperature, leading to a roughening of the SiO2/Si interface morphology. The thermal decomposition kinetics of very thin oxide layers grown on Si(001) and Si(111) surfaces were investigated experimentally by XPS, ultraviolet photoelectron spectroscopy and scanning tunneling microscopy to clarify the void nucleation and growth reaction mechanisms from a viewpoint of the decomposition-induced strain. It was observed that the amount of strained Si atoms increased in proportion to the amount of oxide decomposed during the void nucleation. This was interpreted by using a proposed decomposition model, where there is an undershoot profile of the strain at the periphery of the accumulated void area and the magnitude of the undershoot strain increased in proportion to the amount of vacancies.Based on the above studies, the unified Si oxidation reaction model consist of both the oxide growth and oxide decomposition was verified and further extended.
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