Patent ID: 7928505

Claim:
A semiconductor device comprising: a first semiconductor region of a first conductivity type formed on an upper surface of a semiconductor substrate having a rear surface electrode on a lower surface thereof; a gate trench extending from a front surface of the semiconductor device into the first semiconductor region; a gate electrode positioned in the gate trench so as to interpose an insulator; a second semiconductor region of a second conductivity type formed on the first semiconductor region and adjacent to the gate trench; a third semiconductor region of the first conductivity type formed on the second semiconductor region and adjacent to the gate trench; a field electrode formed on the third semiconductor region; a field trench extending from the front surface of the semiconductor device into the first semiconductor region; a trench-buried field electrode positioned in the field trench so as to interpose an insulator; and a fourth semiconductor region that is less doped than the first semiconductor region and of the first conductivity type, where the fourth semiconductor region is disposed in the first semiconductor region under the field trench, wherein the field electrode contacts with the trench-buried field electrode.