Optical properties of bonded silicon silicide on insulator (S2OI):: a new substrate for electronic and optical devices

A new type of silicon on insulator substrate was fabricated using wafer bonding. The inclusion of a highly conducting buried tungsten silicide layer below the silicon device layer but above the oxide film results in many attractive properties for electronic and optical devices such as high performance bipolar transistors, power devices and optoisolators. Commercial products are being developed using this new (SOI)-O-2 material. However, to fully exploit this material a detailed understanding of its optical and physical nature is required. To this end a study of the buried silicide film? its interfaces and the overlying silicon was carried out using spectroscopic ellipsometry and atomic force microscopy. It was found that the buried silicide undergoes a structural transformation, due to the thermal bonding anneal resulting in a rough interface between it and the silicon overlayer. Crown Copyright (C) 1998/DERA Published by Elsevier Science S.A.