Semiconductor device and fabrication method of semiconductor device

1. A semiconductor device comprising:

a first semiconductor region of a first conductivity type;

a second semiconductor region of a second conductivity type, disposed on a surface of the first semiconductor region, and having an impurity concentration higher than that of the first semiconductor region;

a trench that penetrates the second semiconductor region to reach the first semiconductor region;

a first electrode disposed inside the trench via an insulating film;

a first recess portion disposed deeper than an upper end of the first electrode, in a surface layer of the second semiconductor region, so as to be in direct contact with the trench;

a protruding portion that is formed by a plurality of the first recess portions in the surface layer of the second semiconductor region;

a second electrode embedded in the first recess portion;

a third electrode disposed on a backside of the first semiconductor region, and

a third semiconductor region of the second conductivity type, disposed between the first semiconductor region and the third electrode, and having an impurity concentration higher than the first semiconductor region,

wherein the first recess portion is disposed having a depth equal to or greater than 0.05 μm and equal to or less than 1 μm from the upper end of the first electrode.

2. A semiconductor device comprising:

a first semiconductor region of a first conductivity type;

a second semiconductor region of a second conductivity type, selectively disposed on a surface of the first semiconductor region, and having an impurity concentration higher than that of the first semiconductor region;

a first electrode disposed via an insulating film to cover a portion of a surface of the second semiconductor region;

a second recess portion disposed in a surface layer of the second semiconductor region so as to occupy a portion of a region under the first electrode; and

a second electrode embedded in the second recess portion

wherein the second recess portion occupies the region under the first electrode by a width equal to or greater than 0.05 μm and equal to or less than 1 μm from an end of the first electrode on the side of the second recess portion.

3. The semiconductor device according to claim 2 , further comprising:

a third electrode disposed on a backside of the first semiconductor region, and

a third semiconductor region of the second conductivity type, disposed between the first semiconductor region and the third electrode, and having an impurity concentration higher than the first semiconductor region.