Discussion of origins of high-density trap states in SIMOX wafers

We have demonstrated that separation by implanted oxygen (SIMOX) wafers have high-density trap states in silicon-on-insulator (SOI) layer, which are distributed within about 30 nm from the SOI/buried oxide (BOX) interface in the SOI layer, nano-scale roughness at SOI/BOX interface, and local stress near SOI/BOX interface. Meanwhile, it is reported by Bjorkman et al. that there is a correlation between the stress in the SiO₂ layer and the Si/SiO₂ interface state density at midgap. From these results, we elucidate mutual relationships between trap states, roughness, and local stress. We discuss origin of the high-density trap states from a point of the local stress.