CoSi 2 formation in the presence of interfacial silicon oxide

Evidence is presented that a reactive capping layer may influence the interfacial reaction in a thin film diffusion system. As a prototype system, we describe the ${\mathrm{CoSi}}_2$ formation in the ${\mathrm{Ti/Co/SiO}}_x\mathrm{/Si}$ system. We observed that Ti from the capping layer transforms the ${\mathrm{SiO}}_x$ diffusion barrier into a ${\mathrm{Co}}_x{\mathrm{Ti}}_y{\mathrm{O}}_z$ diffusion membrane, initiating silicide formation. The ${\mathrm{CoSi}}_2$ layer that is formed has a preferential epitaxial orientation. The epitaxial quality is dependent on annealing temperature, Co and Ti thickness. The epitaxial growth may be explained by a combination of Ti-interlayer mediated epitaxy and oxide mediated epitaxy.