Patent ID: 7968943

Claim:
A semiconductor device comprising: an SOI substrate made of a semiconductor substrate and a semiconductor layer of a first conductivity type formed on the semiconductor substrate via a first insulation layer; a drain region of the first conductivity type formed within the semiconductor layer so as to be exposed to a surface of the semiconductor layer; a well region of a second conductivity type formed within the semiconductor layer so as to reach the first insulation layer from the surface of the semiconductor layer, the well region being isolated from the drain region; a source region of the first conductivity type included inside the well region so as to be exposed to a surface of the well region; a drain electrode electrically connected to the drain region; a source electrode electrically connected to the source region; a gate electrode formed via a second insulation layer on the surface of the well region, the gate electrode being provided between the drain region and the source region; and a drain electrode pad formed on a surface of the drain electrode, wherein a region of the semiconductor substrate positioned below the semiconductor layer, except below the drain electrode pad, is removed.