In situ analysis of epitaxial cobalt silicide reaction on silicon (0 0 1)

Abstract

Formation process of CoSi2 on Si(0 0 1) was investigated with in situ reflection high-energy electron diffraction analysis for developing a self-aligned silicide (salicide) process of advanced silicon transistors. A thin Co layer deposited onto a wet chemically oxidized Si(0 0 1) surface silicided at 550°C to form epitaxial CoSi2(0 0 1) without developing polycrystalline subsilicide phase. The oxide remained on the surface up to 750°C and kept the surface flat until its evaporation. It was thus revealed that chemically formed thin oxide on Si(0 0 1) surface is an effective reaction control layer that acts as a reaction barrier to Co/Si subsilicide formation and as a kinematical barrier to surface migration of growing species. These conditions are necessary for fabricating flat and thin epitaxial CoSi2 layers.