Impact of Thin WSIX Insertion in Tungsten Polymetal Gate on Gate Oxide Reliability and Gate Contact Resistance

By inserting thin WSi
_x
layer in tungsten poly gate stack we can effectively relieve the mechanical stress of gate hard mask nitride film, which contributes to the better gate oxide reliability and stress-immunity of transistor. This insertion also could prevent the formation of Si-N dielectric layer atop poly-Si, which could lower the contact resistance between poly and tungsten effectively