Metal gate with PVD amorphous silicon layer and barrier layer for CMOS devices and method of making with a replacement gate process

摘要

A semiconductor structure and method for making the same provides a metal gate on a silicon substrate. The gate includes a high dielectric constant on the substrate, and a physical vapor deposited (PVD) layer of amorphous silicon on the high k gate dielectric. A barrier layer is deposited on the PVD amorphous silicon layer. The metal is then formed on the barrier layer. The work function of the metal gate is substantially the same as a polysilicon gate due to the presence of the PVD amorphous silicon layer. The barrier layer prevents interaction between the PVD amorphous silicon layer and the metal, thereby allowing higher temperature subsequent processing while preserving the work function of the gate.