Semiconductor device and method for manufacturing the same

Abstract

A semiconductor device, including: a semiconductor substrate having first and second main surfaces, and an n-type drift layer therein; a p-type layer provided between the first main surface and the drift layer; and an n-type high-concentration layer provided between the second main surface and the drift layer, and including a plurality of buffer layers. A carrier concentration of the semiconductor device is higher in the n-type high-concentration layer than in the semiconductor substrate. In one of the buffer layers, the carrier concentration decreases both upward and downward in a depth direction of the semiconductor device, from a peak concentration thereof at a peak position to a pre-determined concentration at first and second depth positions respectively above and below the peak position. In the depth direction, a distance between the first depth position and the peak position is larger than a distance between the peak position and the second depth position.