Oxidation mechanisms in WSi₂ thin films

Abstract

The utilization of WSi2 thin films as gate electrodes in field-effect transistors depends on the ability of this material to form a continuous electrically insulating SiO2 overlayer. In the steam oxidation of WSi2 films deposited on polysilicon, SiO2 forms on the surface by means of the rapid diffusion of Si through the WSi 2 which appears in this case to be quite inert. During the initial stages of the steam oxidation of WSi2 films deposited on SiO 2, removal of Si from the silicide (to form SiO2) apparently leads to the formation of free W, rather than the anticipated tungsten-rich W3Si3.