Semiconductor device including first and second buffer layers

A semiconductor device, comprising

• a semiconductor substrate having a main surface, wherein
• the semiconductor substrate includes:
• an N type drift layer;
• an N type first buffer layer disposed on a side of the main surface of the substrate to be adjacent to the drift layer and including proton as an N type impurity;
• and
• an N type second buffer layer disposed on a side of the main surface of the substrate to be adjacent to the first buffer layer and including an N type impurity different from proton,
• the first buffer layer includes:
• a first portion located in a thickness direction of the semiconductor substrate from the main surface of the substrate and having a first peak of an N type impurity concentration;
• and
• a second portion located farther away from the main surface of the substrate than the first portion and having a second peak of an N type impurity concentration,
• a distance from the main surface of the substrate to the first peak is equal to or smaller than 4.0 μm and greater than 0 μm,
• a distance from the first peak to the second peak is equal to or larger than 14.5 μm and less than a distance from the main surface of the substrate to the drift layer, and
• an N type impurity concentration of a portion between the first portion and the second portion is higher than an N type impurity concentration of the drift layer.