Patent ID: 7763910

Claim:
A semiconductor device comprising: a substrate; a first main electrode and a second main electrode spaced apart and facing each other on a surface of the substrate; a gate insulation film formed on the surface of the substrate exposed between the first main electrode and the second main electrode; a gate electrode formed on the gate insulation film between the first main electrode and the second main electrode, the gate electrode having a top surface, a first side facing the first main electrode and, and a second side facing the second main electrode, the gate electrode having a vertical thickness measured from the top surface to the gate insulation film; a sub-insulation film having a thickness less than the vertical thickness of the gate electrode, the sub-insulation film continuously covering substantially all exposed surfaces of the substrate, the first main electrode, the second main electrode, the gate insulation film, and the gate electrode, the sub-insulation film including a first sub-insulation film at least partially covering the top surface of the gate electrode, a second sub-insulation film covering at least the second side of the gate electrode, and a third sub-insulation film covering the gate insulation film where not covered by the gate electrode, the sub-insulation film having an opening partially exposing the gate electrode; and a field plate making electrical contact with the gate electrode by filling the opening in the sub-insulation film, the field plate extending from above the top surface of the gate electrode down the first side of the gate electrode to the third sub-insulation film.