Patent ID: 7851308

Claim:
A production method for manufacturing a semiconductor device, comprising: forming a drift layer of a first conductivity type on a semiconductor substrate; forming a trench in said drift layer; implanting impurities of a second conductivity type in said drift layer through said trench to thereby produce at least one column region of said second conductivity type in said drift layer directly beneath said trench; forming a trench-stuffed layer in said trench, so that an entirety of said trench is substantially stuffed with said trench-stuffed layer; forming a gate insulating layer on said drift layer; forming a gate electrode layer on said gate insulating layer; forming a base region of said second conductivity type in said drift layer; and forming a source region of said first conductivity type in said base region, wherein said gate electrode layer is formed at least in an area located between said source region and said drift layer, and wherein said base region is deeper than said trench-stuffed layer.