A semiconductor device having a field effect transistor (FET) with enhanced performance by reduction of electrical contact resistance of electrodes and resistance of the electrodes per se is disclosed. The FET includes an n-type FET having a channel region formed in a semiconductor substrate, a gate electrode insulatively overlying the channel region, and a pair of source and drain electrodes which are formed at both ends of the channel region. The source/drain electrodes are made of silicide of a first metal. An interface layer that contains a second metal is formed in the interface between the substrate and the first metal. The second metal is smaller in work function than silicide of the first metal, and the second metal silicide is less in work function than the first metal silicide. A fabrication method of the semiconductor device is also disclosed.