Patent ID: 6943428

Claim:
A semiconductor device including: a semiconductor substrate having a first resistivity; a bipolar transistor in said semiconductor substrate at a region of a main surface of said semiconductor substrate, wherein said bipolar transistor includes a semiconductor region of a first conductivity type, having a second resistivity, at a portion of said bipolar transistor that is deepest in said semiconductor substrate; a buried region of a second conductivity type, having a third resistivity, and located within said semiconductor substrate, wherein the second and third resistivities are smaller than the first resistivity, and a portion of said semiconductor substrate having the first resistivity, higher than the second and third resistivities, is interposed between said buried region of the second conductivity type and said semiconductor region of the first conductivity type of said bipolar transistor; and a back plate on a rear surface of said semiconductor substrate and a connection part in said semiconductor substrate electrically connecting said buried region of the second conductivity type to said back plate, said back plate extending across the rear surface of said semiconductor substrate opposite said buried region of the second conductivity type.