Hydrogen annealing treatment used to obtain high quality SOI surfaces

During the past few years, there have been intensive efforts to produce ULSI quality silicon on insulator structures. Several processes have been developed in order to fabricate such SOI structures. These approaches can be placed in two main categories: SIMOX and wafer bonding processes. In most cases, surface quality is always a persistent and current interest for ULSI applications in terms of particles, micro-roughness, oxygen precipitates, etc. This can be easily understood as very thin gate oxide integrity is strongly related to surface micro-defects and as crystal defects in the wafer surface region deteriorate the dielectric breakdown strength of thin oxides. Some chemical mechanical polishing processes have been used for SOI fabrication processes, as have processes using epitaxial layers or plasma assisted chemical etching as a final step. An alternative method consisting of hydrogen annealing is presented in this paper to soften SOI surfaces, as it is performed in bulk silicon applications in order to reduce surface micro-defects (SMD) (Kubota et al., 1994) and surface region micro-defects (SRMD) (Samata et al., 1995).