Control of Co flux through ternary compound for the formation of epitaxial CoSi2 using Co/Ti/Si system

Abstract

A ternary compound of Co₃Ti₂Si is suggested as reaction barrier for the formation of epitaxial CoSi₂ in the Co/Ti/Si system. It has a role to control Co diffusion to the Si substrate, followed by formation of CoSi₂. After Co₃Ti₂Si was formed, CoO and Ti oxide were formed at surface, depending on Ti thickness. In the case of Ti oxide being at surface, the outdiffusion of Ti in ternary compound was accelerated. Then, the decomposition of Co₃Ti₂Si occurred by reaction with Ti oxide, resulting in uniform epitaxial CoSi₂. However, in the case of CoO being at surface, the Ti outdiffusion was suppressed, followed by thermally decomposition of Co₃Ti₂Si. This caused nonuniform Co supply to form nonuniform CoSi₂.