Semiconductor device, and method of manufacturing semiconductor device

A semiconductor device comprising:

• an n-type semiconductor substrate;
• a p-type semiconductor region formed in a front surface side of the semiconductor substrate;
• and
• an n-type field stop region that is formed in a rear surface side of the semiconductor substrate, the n-type field stop region including protons as a donor;
• wherein
• a concentration distribution of the donor in the field stop region in a depth direction has a first peak, a second peak that is closer to the rear surface of the semiconductor substrate than the first peak is, a third peak that is closer to the rear surface of the semiconductor substrate than the second peak is, and a fourth peak that is closer to the rear surface of the semiconductor substrate than the third peak is, and
• a maximum point of peak concentration of the second peak is lower than a maximum point of peak concentration of the first peak.