Patent ID: 6861702

Claim:
A semiconductor device comprising: a semiconductor substrate of a first conductivity type; a plurality of unit devices in the semiconductor substrate; each of the unit devices comprising a source region of a second conductivity type in the surface portion of the semiconductor substrate; a drain region of the second conductivity type in the surface portion of the semiconductor substrate spaced apart from the source region; a trench extending from the surface of the semiconductor substrate between the source region and the drain region and spaced apart from the source region; an insulator in the trench; a drain drift region of the second conductivity type surrounding a side face and a bottom face of the trench and spaced apart from the source region; a gate insulation film on the surface of the semiconductor substrate between the source region end the drain drift region; a gate electrode on the gate insulation film, the gate electrode being extended onto the trench; a source electrode connected electrically to the source region; a drain electrode connected electrically to the drain region; and wherein the side face of the french is extended at an angle between 30 degrees and less than 90 degrees with respect to the surface of the semiconductor substrate.