Patent ID: 7615868

Claim:
A semiconductor device comprising a Group III nitride semiconductor film and an electrode formed on the Group III nitride semiconductor film, wherein the electrode comprising: at least a first metal layer and a second metal layer sequentially formed on the Group III nitride semiconductor film in this order, and an intermediate metal layer interposed between the first metal layer and the semiconductor film, wherein the electrode is in ohmic contact with the Group III nitride semiconductor film with heat treatment at a temperature that is higher than a melting point of Al by 40° C. or more, the Group III nitride semiconductor film is formed on a substrate, the first metal layer is formed with a first metal material, the second metal layer is formed with a second metal material, the intermediate metal layer comprises a metal material having a melting point greater than the melting point of Al, an eutectic alloy formed of the first metal material and the second metal material has a melting point equal to or higher than the temperature of the heat treatment, an alloy of the second metal material and Al starts to be formed at a temperature equal to or greater than the melting point of Al, the first metal material is comprised of Al; and the second metal material comprises at least one metal selected from the group consisting of Nb, Fe, Re, Ta and Zr.