Power transistor with increased avalanche current and energy rating

Abstract

A field-effect transistor involves a drain electrode, a drift region, a body region, a source region, a gate insulator layer, and a gate electrode. The drift region is disposed above the drain electrode. The body region extends down into the drift region from a first upper semiconductor surface. The source region is ladder-shaped and extends down in the body region from a second upper semiconductor surface. The first and second upper semiconductor surfaces are substantially planar and are not coplanar. A first portion of the body region is surrounded laterally by a second portion of the body region. The second portion of the body region and the drift region meet at a body-to-drift boundary. The body-to-drift boundary has a central portion that is non-planar. A gate insulator layer is disposed over the source region and a gate electrode is disposed over the gate insulator.