Patent ID: 8686467
Filing Date: 2014-04-01
Classification: H01L

Abstract:
1. A semiconductor device comprising a semiconductor substrate in which a diode region and an IGBT region are formed, wherein the diode region comprises: a first conductivity type anode region exposed at an upper surface of the semiconductor substrate, a second conductivity type diode drift region formed on a lower surface side of the anode region, and a second conductivity type cathode region, which has a higher density of second conductivity type impurities than in the diode drift region, formed on a lower surface side of the diode drift region, the diode drift region comprises an upper drift layer and a lower drift layer which has a higher density of second conductivity type impurities than the upper drift layer, the IGBT region comprises: a second conductivity type emitter region exposed at the upper surface of the semiconductor substrate, a first conductivity type body region formed at a side and a lower surface side of the emitter region and in contact with an emitter electrode, a second conductivity type IGBT drift region formed on a lower surface side of the body region, a first conductivity type collector region formed on a lower surface side of the IGBT drift region, and a gate electrode facing a range of the body region via an insulating film, wherein the range of the body region separates the emitter region from the IGBT drift region, the IGBT drift region comprises an IGBT drift layer and a buffer layer which has a higher density of second conductivity type impurities than the IGBT drift layer, a low impurity region is formed between the cathode region and the collector region at a lower surface of the semiconductor substrate, the low impurity region comprises at least one of a first conductivity type first low impurity region which has a lower density of first conductivity impurities than that in the collector region and a second conductivity type second low impurity region which has a lower density of second conductivity impurities than that in the cathode region, and the lower drift layer and the buffer layer are continuous with each other on an upper side of the low impurity region.