Patent ID: 7692242

Claim:
A semiconductor device comprising: a low resistance layer formed on a semiconductor substrate; a high resistance layer formed on the low resistance layer; a source region of a first conductivity type formed on a surface region of the high resistance layer; a drain region of the first conductivity type formed at a distance from the source region; a first resurf region of the first conductivity type formed in a surface region of the high resistance layer between the source region and the drain region; a channel region formed between the source region and the first resurf region, the channel region being of a second conductivity type having a gradually lowering impurity concentration; a gate insulating film formed on the channel region; and a gate electrode formed on the gate insulating film, wherein the channel region has a peak concentration of the gradually lowering impurity concentration under one end of the gate electrode and the impurity concentration gradually lowers from the source region toward the first resurf region.