Work function adjustment on fully silicided (FUSI) gate

摘要

A fully silicided gate with a selectable work function includes; a gate dielectric over the substrate; and a first metal silicide layer over the gate dielectric, and a second metal silicide layer wherein the first metal silicide has a different phase then the second metal silicide layer. The metal silicide layers comprises at least one alloy element. The concentration of the alloy element on the interface between the gate dielectric and the metal silicide layers influence the work function of the gate.