Semiconductor device and method for fabricating the same

A semiconductor device of a dual-gate structure including a P-channel type field-effect transistor formed at a first region of a substrate and an N-channel type field-effect transistor formed at a second region of the substrate, includes a gate electrode including a polycrystalline silicon film continuously formed on the substrate to cover the first and second regions and a metal silicide film formed on the polycrystalline silicon film. The polycrystalline silicon film has a P-type part located on the first region and an N-type part coming into contact with the P-type part and located on the second region, and the P-type part is further doped with a heavier element than a P-type impurity that determines a conductivity type of the P-type part.