Patent ID: 6930353

Claim:
A field-effect-type semiconductor device comprising: a channel region of a first conduction-type semiconductor; a first-conduction-type emitter region being in contact with the channel region, and being a first conduction type semiconductor with higher concentration than that of the channel region; a gate electrode penetrating the channel region, and insulated from the channel region and the first-conduction-type emitter region; second-conduction-type emitter regions being insulated from the gate electrode and in contact with the channel region and the first-conduction-type emitter region, the second-conduction-type emitter regions being second conduction-type semiconductors; said second-conduction-type emitter regions and said channel region being arranged alternately and discretely at a surface level; and an emitter electrode being in contact with the channel region and with the first-conduction-type emitter region; wherein an effective channel width, which is a width of a facing portion of a second-conduction-type emitter region and the gate electrode at the surface level is smaller than a whole width of the gate electrode.