Patent ID: 8742474

Claim:
A power semiconductor device having an active region and an electric field reduction region, the device comprising: an emitter region of a first conductivity type; a base region of a second conductivity type in contact with said emitter region; an electrical strength providing region of said first conductivity type in contact with said base region; a collector region of said second conductivity type in contact with said electrical strength providing region; a collector electrode in contact with said collector region; and a buffer region of said first conductivity type formed between said electrical strength providing region and said collector region, wherein a first portion of said collector region is disposed on said active region and a second portion of said collector region is disposed on said electric field reduction region, each portion of said collector region containing a dopant of said second conductivity type, said first portion of said collector region includes alternately disposed first regions and second regions, said first regions having a higher density of carriers of said second conductivity type than said second regions and said second portion of said collector region, each of said second regions having a width larger than each of said first regions a first portion of said buffer region is disposed on said active region and a second portion of said buffer region is disposed on said electric field reduction region, and the second portion of said buffer region has a higher density of carriers of said first conductivity type than said first portion of said buffer region.