| CPC H01L 29/36 (2013.01) [H01L 21/265 (2013.01); H01L 27/0716 (2013.01); H01L 29/1095 (2013.01); H01L 29/7395 (2013.01); H01L 29/861 (2013.01)] | 21 Claims |
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1. 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.
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