Dependence of pmos metal work functions on surface conditions of high-k gate dielectrics

The effective work function of PMOS metal gate electrode as a function of intentionally altered HfO₂ surfaces was investigated. The impact of capping layers, diffusion barriers and interfacial layers on the final work function was also examined. The factors responsible for the change in the effective work function after subsequent thermal treatments were identified and routes to maintain the high effective work function have been demonstrated