Patent ID: 8564097

Claim:
An insulated gate bipolar transistor (IGBT) comprising a semiconductor substrate having the following regions in sequence: (i) a first region of a first conductive type having opposing surfaces, a column region of a second conductive type within the first region extending from a first of said opposing surfaces; (ii) a drift region of the second conductive type; (iii) a second region of the first conductive type; and (iv) a third region of the second conductive type; wherein a gate electrode is disposed to form a current channel between the third region and the drift region, a first electrode is operatively connected to the second region and the third region, and a second electrode is operatively connected to the first region and the column region, wherein the column region is spaced from a second of said opposing surfaces, whereby a forward conduction path extends through the third region, the second region, the drift region, and the first region, and whereby a reverse conduction path extends through the second region, the drift region, the first region and the column region wherein the first region comprises first and second layers, the second layer having a lower doping concentration than the first layer, and wherein reverse conduction occurs through an anti-parallel thyristor structure comprising a first bipolar junction transistor (BJT) formed by the second layer of the first region, the drift region, the second region, and a second bipolar junction transistor (BJT) formed by the column region, the second layer of the first region and the drift region.