Capped dual metal gate transistors for cmos process and method for making the same

Abstract

A first gate () and a second gate () are preferably PMOS and NMOS transistors, respectively, formed in an n-type well () and a p-type well (). In a preferred embodiment first gate () includes a first metal layer () of titanium nitride on a gate dielectric (), a second metal layer () of tantalum silicon nitride and a silicon containing layer () of polysilicon. Second gate () includes second metal layer () of a tantalum silicon nitride layer on the gate dielectric () and a silicon containing layer () of polysilicon. First spacers () are formed adjacent the sidewalls of the gates to protect the metals from chemistries used to remove photoresist masks during implant steps. Since the chemistries used are selective to polysilicon, the spacers () need not protect the polysilicon capping layers, thereby increasing the process margin of the spacer etch process. The polysilicon cap also facilitates silicidation of the gates.