Prevention of fluorine-induced gate oxide degradation in WSi polycide structure

摘要

A new method of fabricating a polycide gate is described. A gate polysilicon layer is provided a gate oxide layer on the surface of a substrate. A thin conducting diffusion barrier is deposited overlying the gate polysilicon layer. A of tungsten silicide is deposited overlying the thin diffusion barrier layer wherein a reaction gas in the deposition contains fluorine atoms and wherein fluorine atoms are incorporated into the tungsten layer. The gate polysilicon, thin conducting barrier, and tungsten silicide layers are patterned form the polycide gate structures. The wafer is annealed complete formation of the polycide gate structures wherein number of fluorine atoms from the tungsten silicide layer into the gate polysilicon layer are minimized by presence of the thin conducting diffusion barrier layer wherein because the diffusion of the fluorine atoms is the thickness of the gate oxide layer does not This prevents the device from degradation such as voltage shift and saturation current descrease.