Patent ID: 9640613
Date: 2017-05-02
CPC Classifications: H01L

Claim:
1. A semiconductor device having a trench-gate field effect transistor, comprising: a semiconductor substrate having a first conductivity type; a trench formed in a main surface of the semiconductor substrate; a gate electrode for the trench-gate field effect transistor formed in the trench via a gate insulating film; a first semiconductor region having a second conductivity type opposite to the first conductivity type and formed in the semiconductor substrate so as to be adjacent to the trench, the first semiconductor region being for forming a channel of the trench-gate field effect transistor; a second semiconductor region having the first conductivity type and formed over the first semiconductor region in the semiconductor substrate so as to be adjacent to the trench, the second semiconductor region being for a source of the trench-gate field effect transistor; a third semiconductor region having the second conductivity type and formed under the first semiconductor region in the semiconductor substrate; a fourth semiconductor region having the second conductivity type and formed under the third semiconductor region in the semiconductor substrate; and a back-surface electrode formed over a back surface of the semiconductor substrate which is opposite to the main surface thereof, the back-surface electrode being for a drain of the trench-gate field effect transistor, wherein the third semiconductor region is internally included in the fourth semiconductor region in plan view, and wherein a two-dimensional size of the fourth semiconductor region is larger than a two-dimensional size of the third semiconductor region.