Process dependence of the SiO₂/Si(100) interface structure

Synchrotron radiation photoemission spectroscopy has been used to study thermal SiO₂/Si(100) interfaces. Oxides were grown at 700°C and were then post-annealed at higher temperatures. Various Si oxidation states Si^+x (x represents the oxidation state) at the interface were detected from Si 2p core level measurements. The results show that the amount of both Si⁺³ and Si⁺² increases while that of Si ⁺¹ remains constant as a function of anneal temperature. It is also found that the peak width of the substrate Si 2p increases with increasing anneal temperature. This is attributed to the disordering of substrate Si atoms adjacent to the interface. The above results are interpreted in terms of anneal-induced structural relaxation to reduce the long-range strain on both sides of the interface.