IGBT with self-aligning cathode pattern and method for producing it

Claim 1

An insulated-gate bipolar transistor comprising a semiconductor substrate of a first conduction type which is bounded by a first and a second main area; a cathode which is allocated to the first main area, and an anode which is formed by a metallization covering the second main area; an emitter layer of a second conduction type which is inserted into the semiconductor substrate from the anode-side main area; a plurality of collector regions of the second conduction type which are inserted into the semiconductor substrate from the cathode-side main area, the semiconductor substrate penetrating to the cathode-side main area between two adjacent collector regions; a gate electrode which is formed by a conducting layer which is arranged and insulated above the cathode-side main area and extends from a collector region over the semiconductor substrate penetrating to the surface to the adjacent collector region; a number of source regions of the first conduction type which are inserted into the collector regions and which exhibit a length L and at right angles thereto a width W in the direction of an adjacent collector region; wherein the length L of the source regions is selected such that there are at least two channel regions produced for each source region, the channel regions comprising a part of a collector region which penetrates to the cathode-side main area between the source region and semiconductor substrate and which is covered by the gate electrode, the width of the source regions is selected to be of the order of magnitude of microns such that holes which flow from the anode to the cathode underneath the source regions polarize a PN-junction which is formed by the source regions and the adjacent collector regions in the forward direction, and such that a voltage drop across said PN-junction remains below the inbuilt forward voltage of the PN junction at any time.