Ultrathin silicide formation for ULSI devices

Recently, the growth of epitaxial CoSi, layers was demonstrated using the oxide mediated epitaxy COME) technique. A thin SiO, interlayer, grown in a peroxide-containing aqueous solution, induced the growth of nearly perfect CoSi, on practically all surfaces of Si. With deposited cobalt, a optimum thickness range of l-3 nm was observed, independent of the doping level and the orientation of the silicon. After the OME growth, the SiO, layer was found to remain largely on the surface and act as a cap of the silicide layer. An interesting result of the surface oxide cap was a significant re-evaporation of cobalt observed during deposition at elevated temperatures. Thicker (lo-30 nm), excellent quality, CoSi, single crystal thin films were grown by repeated growth sequences on Si(lOO), (1 IO), (11 l), (211) and (511). Additionally, OME growth was found not to depend on linewidth and doping level, making it an attractive technique for ULSI applications.