A semiconductor device and a method of fabricating the same, the semiconductor device includes a substrate, a first gate and a second gate. The first gate is disposed on the substrate and includes a first gate insulating layer, a polysilicon layer, a silicide layer and a protective layer stacked with each other on the substrate and a first spacer surrounds the first gate insulating layer, the polysilicon layer, the silicide layer and the protective layer. The second gate is disposed on the substrate and includes a second gate insulating layer, a work function metal layer and a conductive layer stacked with each other on the substrate, and a second spacer surrounds the second gate insulating layer, the work function metal layer and the conductive layer.