Method for forming a metal gate integrated with a source and drain salicide process with oxynitride spacers

Abstract

A method of forming a metal gate integrated with a salicide process on the source and drain regions. A gate dielectric layer and polysilicon/silicon dioxide/silicon nitride dummy gate layers are formed over a substrate structure and patterned to form dummy structures, comprising at least one dummy gate structure. Lightly doped source and drain regions, sidewall spacers, and source and drain regions are formed adjacent to the dummy gate structure. A silicide layer is formed on the source and drain regions by depositing titanium/titanium nitride, performing a rapid thermal anneal, selectively removing unreacted titanium/titanium nitride using NH OH, and performing a second rapid thermal anneal. A blanket dielectric layer is formed over the dummy structures. The blanket dielectric layer, the spacers and the silicon nitride layer of the dummy structures are planarized using a chemical mechanical polishing process. The silicon nitride layer and the silicon dioxide layer of the dummy structures are removed. A titanium nitride layer is formed over the polysilicon layer of the dummy structures, and a tungsten layer is deposited over the titanium nitride layer. The tungsten layer and titanium nitride layer are planarized using a chemical mechanical polishing process, thereby forming polysilicon/titanium nitride/tungsten structures.