Patent ID: 7786537

Claim:
A semiconductor device comprising: a silicon substrate; a P channel type field effect transistor including a first gate insulating film on the silicon substrate, a first gate electrode on the first gate insulating film and a first source/drain region; and an N channel type field effect transistor including a second gate insulating film on the silicon substrate, a second gate electrode on the second gate insulating film and a second source/drain region, wherein the first gate electrode is entirely made of a silicide of metal M, and the second gate electrode comprises a silicide region of the same kind of metal as the metal M at least in an upper portion of the second gate electrode including its upper surface, the concentration of the metal M in the silicide region is lower than that of the metal M in the silicide of the first gate electrode, and a barrier layer region in an upper portion including the upper surface of the second gate electrode, the barrier layer region containing a metal diffusion suppressing element at a concentration higher than that in the lower portion.