Patent ID: 7432135

Claim:
A method of manufacturing a semiconductor device having a transistor controlling a current flowing in a base layer by a gate electrode and a diode, comprising the steps of: preparing a semiconductor substrate of a first conductivity type having first and second major surfaces; forming a first conductivity type semiconductor layer on the first major surface of the semiconductor substrate; forming a base layer of a second conductivity type on the surface of the semiconductor layer; forming a pair of groove portions penetrating the base layer from the first major surface and reaching at least the semiconductor layer; disposing an insulation film inside the groove portion and forming a gate electrode inside the groove portion through the insulation film forming an inter-layer insulation film to cover the top of the groove portion; forming a first conductivity type semiconductor layer and a second conductivity type semiconductor layer on the second major surface of the semiconductor substrate; and disposing an emitter region along the groove portions only in a section of the base layer on the first major surface and located between the pair of groove portions.