Patent ID: 8362549

Claim:
A trench gate semiconductor device comprising: a semiconductor substrate comprising a drift region of a second conductivity type and a body region of a first conductivity type on the drift region; a source region of the second conductivity type formed selectively in a surface portion of the body region; a first trench formed from a surface of the body region to the drift region, the first trench being in contact with the source region; a polysilicon gate electrode in a lower portion of the first trench with a gate oxide film interposed between the polysilicon gate electrode and an inner wall of the first trench; an insulator in an upper portion of the first trench, the insulator being on the polysilicon gate electrode; the source region comprising a lower end surface positioned lower than an upper surface of the polysilicon gate electrode; a second trench in a surface portion of the semiconductor substrate adjacent the first trench, the second trench comprising a slanted inner surface providing the second trench with a widest trench width in an opening thereof and a bottom plane positioned lower than the lower end surface of the source region, the slanted inner surface being in contact with the source region in contact with the first trench; a body-contact region of the first conductivity type in the surface portion of the body region, the body-contact region being in contact with the slanted inner surface of the second trench; and the source region being doped more heavily on a side of the first trench surface.