| 摘要 |
PURPOSE:To shorten a switching-OFF time and to improve a controllable current, by a constitution wherein a first base region having high concentration impurities on the side close to an n-base layer and a second p-base layer having low concentration impurities on the side close to an n-emitter layer are provided in a p-base layer, and the bottom of a recess part reaches the first p-base layer. CONSTITUTION:From both surfaces of a semiconductor substrate (n base), a p-emitter layer 12 and a first p-base layer 13 are formed by thermal diffusion. It is desirable that the surface impurity concentration of the first p-base layer 13 is 1X10<17>cm<-3> or more. Thereafter, on the surface of the first p-base layer 13, a second p-base layer 20, which has the impurity concentration of 1X10<16>cm<-3> or less, is formed to a thickness of 2-20mum. On the surface of the second p-base layer 20, an n-emitter layer 14 is formed. With a cathode region 15, which has a plurality of stripe shaped surface parts, being made to remain, the other part is etched from the surface of the n-emitter layer 14, and a recess part 16 is formed. At this time, the bottom of the recess part 16 reaches the first p-base layer 13 penetrating through the n-emitter layer 14 and the second p-base layer 20. |
