Method to simultaneously form both fully silicided and partially silicided dual work function transistor gates during the manufacture of a semiconductor device, semiconductor devices, and systems including same

摘要

A method for forming transistor gates having two different work functions comprises forming a first polysilicon layer which may be doped with n-type dopants. The first polysilicon layer comprises an inhibitor material at select locations which retards silicide formation. A second polysilicon layer is formed over the first polysilicon layer. The first and second polysilicon layers are masked and etched to define transistor structures, some of which comprise the inhibitor and some which are free from the inhibitor. Dielectric spacers are formed, then a metal such as cobalt is deposited over the transistor structures. A thermal process may be used to react the metal with the transistor structures to form fully silicided gates from the inhibitor-free structures and partially silicided gates from the structures comprising the inhibitor. Fully silicided gates have the work function of a metal gate while partially silicided gates may have the work function of doped polysilicon.