Patent ID: 7498635

Claim:
A field effect transistor, comprising: a base layer of a first conductivity type formed on a surface of an insulating substrate; a source layer of a second conductivity type selectively formed on a surface of the base layer; a drain layer of the second conductivity type formed on the insulating substrate apart from the base layer of the first conductivity type; a first drift layer of a first conductivity type formed in a region between the base layer and the drain layer; a second drift layer of a second conductivity type formed in a region between the base layer and the drain layer, laminated on the first drift layer; and a gate electrode formed on the surface of the base layer and the second drift layer via a gate insulating film, wherein the base layer, the drain layer and the drift layers compose an active layer, which is formed in a pillar shape and the gate electrode is provided on both sides of the pillar shaped active layer.