US Patent 7365404 Semiconductor device having silicide reaction blocking region

A semiconductor device has a silicon substrate, an n-type well region formed in the silicon substrate, first and second source/drain regions constructed of a p-type diffusion layer formed on the n-type well region, a gate insulator formed in a region located between the first source/drain region and the second source/drain region and a polysilicon formed on the gate insulator. The semiconductor device has oxygen-rich layers for blocking a silicide reaction, which layers are formed in an uppermost portion of the silicon substrate on the side of the polysilicon, and has an oxygen-rich layer for blocking the silicide reaction, which layer is formed in an upper portion of the polysilicon.