Abstract: The present invention provides a method of manufacturing a semiconductor device. The semiconductor device (100), among other possible elements, includes a first transistor (120) located over a semiconductor substrate (110), wherein the first transistor (120) has a gate electrode (135) that includes a metal silicide layer 135a over which is located a silicon gate layer (135b) together which have a work function associated therewith, and a second transistor (125) located over the semiconductor substrate (110) and proximate the first transistor (120), wherein the second transistor (125) also includes a gate electrode (160) that includes a metal silicide layer (160a) over which is located a silicon gate layer (160b) together which have a different work function from that of the first gate electrode (135) associated therewith.

Abstract: Methods are presented for fabricating transistor gate structures, wherein upper and lower metal suicides are formed above a gate dielectric. In one example, the lower silicide is formed by depositing a thin first silicon-containing material over the gate dielectric, which is implanted and then reacted with a first metal by annealing to form the lower silicide. A capping layer can be formed over the first metal prior to annealing, to prevent oxidation of the metal prior to silicidation, and a barrier layer can be formed over the lower silicide to prevent reaction with subsequently formed silicon material. In another example, the lower silicide is a multilayer silicide structure including a plurality of metal silicide sublayers.