  The formation of hafnium silicate films (HfSixOy) for use as gate oxides with
large dielectric constant by solid state reaction of Hf metal and SiO2 was
investigated. Thin, fully reacted silicate films could be formed, and were
thermally stable in vacuum to temperatures in excess of 800 C. The interface
between a hafnium silicate layer and the silicon substrate was shown to be
stable against SiO2 formation. The results suggest a new processing route for
production of a gate insulator having low equivalent oxide thickness.
