First-principles study of excess Si transport in Si oxide on Si substrate using two-layer-oxide model for thermally oxidized interface

Abstract A two-layer-oxide model for the thermal Si oxide/Si interface is constructed, and the transport pathway and energy landscape of excess Si within the Si oxide, from the interface to the surface, are successfully identified. The results reveal that excess Si can accumulate at the quartz/cristobalite boundary as well as at the cristobalite surface, with maximum barrier heights in good agreement with experimental values. Two mechanisms for converting the interfacial quartz layer into the upper cristobalite layer during oxidation are suggested: one involving incorporation of excess Si, and the other involving Si emission. Overall, the cristobalite/quartz/Si interface model presented in this study provides a reliable framework for simulating numerous key important properties and characteristics of both the thermal oxidation process and the resulting oxide interface structure.