Method to enhance channel stress in cmos processes

Abstract

The invention provides a method of fabricating a semiconductor device that enhances the amount of stress that is transmitted to the channel region for carrier mobility enhancement. In one embodiment an amorphous region is formed at or near the gate dielectric interface prior to source/drain anneal. In a second embodiment the gate material is amorphous as deposited and processing temperatures are kept below the gate material crystallization temperature until stress enhancement processing has been completed. The amorphous gate material deforms during high temperature anneal and converts from an amorphous to a polycrystalline phase allowing more stress to be transmitted into the channel region. This enhances carrier mobility and improves transistor drive current.