US Patent 9577046 Semiconductor device

A semiconductor device includes a semiconductor layer having a first surface and a second surface, a first electrode on the first surface, a second electrode on the second surface, a first semiconductor region of a first conductivity type in the semiconductor layer, a second semiconductor region of a second conductivity type in an element region of the semiconductor layer between the first semiconductor region and the first electrode, a third semiconductor region of the second conductivity type between the second semiconductor region and the first electrode, and a fourth semiconductor region of the second conductivity type in a termination region of the semiconductor layer inwardly of the first surface. A distance between the fourth semiconductor region and the second surface is greater than a distance between the second semiconductor region and the second surface.