Patent ID: 9608073
Date: 2017-03-28
CPC Classifications: H01L,H03K

Claim:
1. A semiconductor device comprising: a base layer of a first conductivity type having a MOS gate structure being formed on a front surface side thereof; a first collector layer of a second conductivity type formed on a rear surface side of the base layer; a second collector layer of the second conductivity type formed on a rear surface side of the first collector layer with a material that is the same with that of the base layer, the second collector layer being formed to be thinner than the first collector layer and to have a higher impurity concentration than that of the first collector layer; a collector electrode formed on a rear surface side of the second collector layer; and a separation layer of the second conductivity type that surrounds the MOS gate structure on a front surface of the base layer and is formed from a front surface of the base layer to a front surface of the first collector layer, wherein the first collector layer has a region that is adjacent to the separation layer having both impurities diffused from the front surface side of the base layer and impurities diffused from the rear surface side of the base layer.