Patent ID: 7986004

Claim:
A semiconductor device including an offset drain-type MOS transistor having a channel of a first conductivity type on a semiconductor substrate, the semiconductor device comprising: a semiconductor substrate of a first conductivity type; a semiconductor layer of a second conductivity type on the semiconductor substrate; a buried layer of the second conductivity type between the semiconductor substrate and the semiconductor layer; a drain region including a high concentration drain layer of the first conductivity type on a surface of the semiconductor layer; a source region including a high concentration source layer of the first conductivity type on the surface of the semiconductor layer; a gate oxide film between the drain region and the source region and on an active region on the surface of the semiconductor layer; a LOCOS oxide film between the drain region and the gate oxide film and on the surface of the semiconductor layer; a gate electrode on the gate oxide film, partially covering the LOCOS oxide film; an offset layer of the first conductivity type below the LOCOS oxide film; and a plurality of diffusion layers of the first conductivity type in striped shapes at nearly the same depth and directly beneath the offset layer and the drain layer in and parallel to the surface of the semiconductor layer.