Patent ID: 8304827

Claim:
A semiconductor device comprising: a substrate of a first conductivity type; a first buried layer of a second conductivity type that is formed in a device formation region on the substrate and is in a floating state; a second buried layer of the first conductivity type formed on the first buried layer; an epitaxial layer of the second conductivity type formed on the second buried layer; a first diffusion region of the first conductivity type that are formed on the second buried layer and surround the epitaxial layer; a second diffusion region of the first conductive type, at least a part of which is formed on the first diffusion region; a third diffusion region of the first conductivity type formed on the second diffusion region; a first electrode formed on the third diffusion region; a fourth diffusion region of the second conductivity type, at least a part of which is formed in the epitaxial layer; a fifth diffusion region of the first conductivity type and a sixth diffusion region of the second conductivity type formed on the fourth diffusion region; a second electrode formed on the fifth diffusion region and the sixth diffusion region; and a third electrode formed between the third diffusion region and the fifth diffusion region and above the epitaxial layer via an insulating film, and short-circuited with the fifth diffusion region and the sixth diffusion region via the second electrode.