Patent ID: 7838945

Claim:
A semiconductor device, comprising: a semiconductor substrate; an element isolation region on the semiconductor substrate; a first active region and a second active region disposed on the semiconductor substrate and separated from each other by the element isolation region; a line-shaped electrode disposed from over the first active region to over the second active region via the element isolation region; a first field effect transistor comprising a first gate insulating film on the first active region, a first gate electrode composed of the line-shaped electrode on the first gate insulating film, and a first source/drain region in the first active region; and a second field effect transistor comprising a second gate insulating film on the second active region, a second gate electrode composed of the line-shaped electrode on the second gate insulating film, and a second source/drain region in the second active region, wherein part of the line-shaped electrode over the first active region and part of the line-shaped electrode over the second active region are formed of mutually different materials; the line-shaped electrode comprises a diffusion restraining region having thickness T of the line-shaped electrode in a direction perpendicular to the substrate thinner than thickness T of the line-shaped electrode over the first and second active regions, the diffusion restraining region being provided over the element isolation region and spanning the whole width of the line-shaped electrode in the gate length direction; and thickness Tr of the line-shaped electrode in the diffusion restraining region is not less than 10 nm but not more than 30 nm.