Dual work function gate electrodes using doped polysilicon and a metal silicon germanium compound

摘要

A dielectric layer ( 50 ) is formed over a semiconductor ( 10 ) that contains a first region ( 20 ) and a second region ( 30 ). A polysilicon layer is formed over the dielectric layer ( 50 ) and over the first region ( 20 ) and the second region ( 30 ). The polysilicon layer can comprise 0 to 50 atomic percent of germanium. A metal layer is formed over the polysilicon layer and one of the regions and reacted with the underlying polysilicon layer to form a metal silicide or a metal germano silicide. The polysilicon and metal silicide or germano silicide regions are etched to form transistor gate regions ( 60 ) and ( 90 ) respectively. If desired a cladding layer ( 100 ) can be formed above the metal gate structures.