Semiconductor device and method of manufacturing semiconductor device

A semiconductor device comprising:

• a bipolar-type semiconductor element including:
• a semiconductor substrate having a first main surface and a second main surface and having a drift layer of a first conductivity type formed therein;
• a plurality of trenches formed in the first main surface of the semiconductor substrate;
• an electrode embedded in each of the plurality of trenches via an insulation film;
• a mesa region that is a region located between the plurality of trenches in the semiconductor substrate;
• and
• a source layer of the first conductivity type or a contact layer of a second conductivity type formed in a surface layer of the mesa region on a side closer to the first main surface,
• wherein the mesa region includes dislocations in positions located on a side closer to the second main surface than the source layer or the contact layer, the dislocations having an overall length greater than a width of the mesa region.