Patent ID: 7589389

Claim:
A semiconductor device comprising: a semiconductor layer of a second conductivity type formed above a semiconductor substrate; a base layer of a first conductivity type selectively formed at a surface of the semiconductor layer; a gate electrode formed on the base layer via an insulating film; a source layer of a second conductivity type selectively formed at a surface of the base layer at one side of the gate electrode; an channel implantation layer selectively formed at the surface of the base layer so as to be adjacent to the source layer below the gate electrode, the channel implantation layer having a higher concentration than the base layer; a RESURF layer of the second conductivity type selectively formed at the surface of the base layer and the surface of the semiconductor layer at the other side of the gate electrode, so as to overlap the base layer and the semiconductor layer, wherein the RESURF layer includes a first portion at a side of the gate electrode and a second portion at a side opposite to the gate electrode which has a higher concentration than the first portion, the first portion is formed at the surface of the base layer and the second portion is formed so as to overlap the base layer and the semiconductor layer; and a drain layer of the second conductivity type selectively formed at the surface of the semiconductor layer so as to be adjacent to the RESURF layer, the drain layer having a higher concentration than the RESURF layer and the semiconductor layer.