Semiconductor device

1. A semiconductor device comprising:

a substrate of a first conductivity type, having second-conductivity-type base regions on a first surface thereof;

trench gates provided in the first surface of said substrate, disposed while being spaced from each other in a first direction in plan view;

first-conductivity-type source regions formed in said first surface, and to a depth shallower than said base regions; and

a plurality of second-conductivity-type column regions formed in said substrate and under said base regions, and located between two adjacent trench gates in plan view,

wherein, between two adjacent trench gates, said plurality of column regions are disposed while being spaced from each other in a second direction normal to said first direction,

the center of each column region falls on the center line between two adjacent trench gates in said first direction, and

said column regions are not formed under said trench gates.

2. The semiconductor device as claimed in claim 1 ,

wherein, in said second direction in plan view, said source regions are formed over a region between every adjacent ones of said plurality of column region.

3. The semiconductor device as claimed in claim 1 ,

wherein, said source regions are not located between said column regions and said trench gates in the said first direction in plan view.

4. The semiconductor device as claimed in claim 1 ,

wherein each of said plurality of column regions is composed of a plurality of subcolumn regions spaced from each other in a depth-wise direction.