Patent ID: 8450797

Claim:
A semiconductor device, comprising: a semiconductor substrate of a first conductivity type; a buried layer of a second conductivity type on the semiconductor substrate; an epitaxial layer of the second conductivity type on the buried layer and having a shallow trench region in a surface thereof; a first diffusion layer region of the first conductivity type in the epitaxial layer of the second conductivity type; a deep trench region extending from the first diffusion layer region in the epitaxial layer; a gate insulating film on an inner wall of the deep trench region; a gate electrode comprising polysilicon in the deep trench region and in contact with the gate insulating film; a source region of the second conductivity type in a surface of the first diffusion layer region; and a heavily doped diffusion layer of the first conductivity type in the surface of the first diffusion layer region, wherein the first diffusion layer region is shaped so as to include a second diffusion layer region at a bottom portion thereof and at a position spaced away from the deep trench region, the second diffusion layer region extending in the epitaxial layer below the shallow trench region, and wherein the buried layer comprises a heavily doped drain, the epitaxial layer comprises a lightly doped drain, the first diffusion layer region comprise a body region, and the heavily doped diffusion layer comprises a body contact region.