Semiconductor device

Abstract

A semiconductor device includes a semiconductor substrate; a first base region of a first conductivity type provided in the semiconductor substrate; a buffer region of the first conductivity type provided on a lower surface of the first base region and having an impurity concentration higher than an impurity concentration of the first base region; an emitter region of a second conductivity type provided on a lower surface of the buffer region; a second base region of the second conductivity type selectively provided on an upper surface of the first base region; a diffusion region of the first conductivity type selectively provided on an upper surface of the second base region; a control electrode; a first main electrode; and a second main electrode. A junction interface between the buffer region and the first base region has a concave portion and a convex portion.

1 . A semiconductor device comprising:
 a semiconductor substrate having an upper surface and a lower surface opposed to each other;   a first semiconductor region of a first conductivity type provided in the semiconductor substrate and having a first impurity concentration;   an emitter region of the first conductivity type provided on a lower surface of the first semiconductor region and having a second impurity concentration higher than the first impurity concentration;   an emitter region of a second conductivity type provided on an upper surface of the first semiconductor region and having a third impurity concentration;   a first main electrode provided to be electrically connected to the emitter region of the first conductivity type; and   a second main electrode provided to be electrically connected to the emitter region of the second conductivity type,   a diffusion region of the first conductivity type having a fourth impurity concentration higher than the first impurity concentration being present in the first semiconductor region, and   a diffusion region of the second conductivity type having a fifth impurity concentration higher than the third impurity concentration being present closer to a surface of the emitter region of the first conductivity type than the diffusion region of the first conductivity type present in the first semiconductor region.   
     
     
         2 . The semiconductor device according to  claim 1 , wherein a plurality of said diffusion regions of the first conductivity type and a plurality of said diffusion regions of the second conductivity type are provided to be scattered in the first semiconductor region. 
     
     
         3 . The semiconductor device according to  claim 1 , wherein the diffusion region of the first conductivity type is provided closer to the first main electrode than to a center of the first semiconductor region.