Patent ID: 8129799

Claim:
A semiconductor device, comprising: a lowly doped region of a first conduction type formed in a substrate; a channel region arranged in the lowly doped region of the first conduction type; a gate electrode formed over the channel region; a drain region of a second conduction type formed in a part of the surface of the lowly doped region of the first conduction type; a drain electrode formed within the drain region of the second conduction type; a source region of the second conduction type formed in a part of the surface of the lowly doped region of the first conduction type and formed in a region facing the drain region of the second conduction type so that the channel region lies between the source region and the drain region; a source electrode formed within the source region of the second conduction type; a first device isolation film lying between the channel region and the drain electrode and formed within the drain region of the second conduction type; and a second device isolation film lying between the channel region and the source electrode and formed within the source region of the second conduction type, wherein the first device isolation film is greater in film thickness than the second device isolation film.