Patent ID: 8754479

Claim:
A semiconductor device comprising: a semiconductor substrate of a first general conductivity type; an epitaxial layer of a second general conductivity type formed on the semiconductor substrate; a first buried layer of the second general conductivity type formed between the semiconductor substrate and the epitaxial layer so as to leave an opening in which a PN junction between the semiconductor substrate and the epitaxial layer is preserved; a second buried layer of the first general conductivity type connected to a peripheral edge region of the first buried layer and extending from inside the semiconductor substrate into the epitaxial layer; a first drawing layer of the first general conductivity type extending from a surface portion of the epitaxial layer into the epitaxial layer so as to be connected to the second buried layer; a second drawing layer of the first general conductivity type extending from a surface portion of the epitaxial layer into the epitaxial layer so as to be surrounded by the second buried layer and the first drawing layer in plan view of the semiconductor substrate; a first diffusion layer of the first general conductivity foamed in a surface portion of the epitaxial layer including the second drawing layer; a second diffusion layer of the second general conductivity type connected to and surrounding the first diffusion layer in the plan view; a cathode electrode connected to the first diffusion layer and the second diffusion layer; and an anode electrode connected to the first drawing layer, wherein the first buried layer and the second buried layer are configured to form a PN junction diode, the second drawing layer, the epitaxial layer and the semiconductor substrate are configured to form a parasitic bipolar transistor, or the second drawing layer, the epitaxial layer and the second buried layer are configured to form a parasitic bipolar transistor, and the PN junction diode and the parasitic bipolar transistor are configured to form an ESD protection element.