A novel process to form cobalt silicided p/sup +/ poly-Si gates by BF/sub 2//sup +/ implantation into bilayered CoSi/a-Si films and subsequent anneal

A novel process that implants BF/sub 2//sup +/ ions into thin bilayered CoSi/a-Si films has been shown to form cobalt silicided p/sup +/ poly-Si gates with excellent gate oxide integrity and very small flatband shift. The effects of not only using the CoSi layer as an implantation barrier but also keeping the a-Si underlayer during the initial silicide formation both significantly suppress the boron penetration through thin gate oxide.