Semiconductor device

A semiconductor device, comprising:

• a drift region of a first conductivity type which is provided in a semiconductor substrate;
• and
• a buffer region of the first conductivity type which is provided between the drift region and a lower surface of the semiconductor substrate, and has three or more concentration peaks higher than a doping concentration of the drift region of the semiconductor substrate in a depth direction,
• wherein three or more of the concentration peaks includes
• a shallowest peak closest to the lower surface of the semiconductor substrate,
• a high concentration peak arranged at an upper side than the lower surface of the semiconductor substrate than the shallowest peak, and
• one or more low concentration peaks which are arranged at an upper side than the lower surface of the semiconductor substrate than the high concentration peak;
• and of which the doping concentration is ⅕ or less of the high concentration peak;
• and
• wherein
• the three or more of the concentration peaks include two or more of the low concentration peaks, and
• the shallowest peak has a doping concentration higher than the high concentration peak.