Patent ID: 8159034

Claim:
A semiconductor device, comprising: a semiconductor substrate having a surface region, the surface region being provided with an N-type semiconductor region and a P-type semiconductor region; a P-channel insulated gate field effect transistor formed on the N-type semiconductor region, the P-channel insulated gate field effect transistor having a P-type source layer and a P-type drain layer formed apart from each other in the N-type semiconductor region, a first insulating film formed on the N-type semiconductor region, and a lower gate electrode film formed on the first insulating film and located above a region between the P-type source and drain layers and an upper gate electrode film containing silicon and P-type impurities formed on the lower gate electrode film, the lower gate electrode film being made of a material different from that of the upper gate electrode film and composed of at least one selected from a metal film, a metal nitride film, a metal silicide film and a metal carbide film; and an N-channel insulated gate field effect transistor formed on the P-type semiconductor region, the N-channel insulated gate field effect transistor having an N-type source layer and an N-type drain layer formed apart from each other in the P-type semiconductor region, a second insulating film formed on the P-type semiconductor region, and a third gate electrode film containing silicon and N-type impurities formed on the second insulating film and located above a region between the N-type source and drain layers, the third gate electrode film being thicker than the upper gate electrode film.