Patent ID: 7659574

Claim:
A semiconductor device having a MOSFET, comprising: a semiconductor substrate having a main surface and a back surface opposite to the main surface, said semiconductor substrate including an active cell area and a gate wiring area, and said semiconductor substrate having a first conductivity type; a well region in the main surface in the active cell area, said well region having a second conductivity type opposite to the first conductivity type; a first groove portion in the main surface in the active cell area, said first groove portion penetrating the well region; a gate oxide film of the MOSFET on an inner surface of the first groove portion; a gate electrode of the MOSFET over the gate oxide film, said gate electrode being in the first groove portion; a source region of the MOSFET in the well region in the active cell area, said source region contacting the first groove portion, and said source region having the first conductivity type; a gate drawing electrode over the main surface in said gate wiring area such that an upper surface of the gate drawing electrode is higher than an upper surface of the gate electrode, said gate drawing electrode being integrally formed with the gate electrode; an insulating film over the gate electrode and gate drawing electrode, the insulating film having an opening therein in the gate wiring area, said opening extending through the insulating film to the gate drawing electrode; a gate wiring over the insulating film and electrically connected with the gate drawing electrode through the opening; a source electrode over the insulating film and electrically connected with the source region in the active cell area; and a drain electrode over the back surface and electrically connected with the semiconductor substrate having the first conductivity type, wherein an upper surface of the gate electrode is lower than the main surface of the semiconductor substrate so as to form a second groove portion in the active cell area, and wherein the insulating film is disposed inside the second groove portion, wherein the gate drawing electrode has a first part and a second part adjoining to the first part, the first part of the gate drawing electrode has a plurality of slits in a plan view, the insulating film is disposed inside the plurality of slits, and the opening extends to the first part of the gate drawing electrode.