Patent ID: 7619299

Claim:
A semiconductor device comprising: a semiconductor substrate of one conductivity type; an epitaxial layer of opposite conductivity type formed on the semiconductor substrate; a first buried diffusion layer of the one conductivity type, which is formed so as to extend in the semiconductor substrate and the epitaxial layer, and which is used as a collector region; a first buried diffusion layer of the opposite conductivity type, which is formed so as to extend in the semiconductor substrate and the epitaxial layer, and which isolates the semiconductor substrate from the first buried diffusion layer of the one conductivity type by junction isolation; a second buried diffusion layer of the opposite conductivity type, a forming area thereof overlapping the first buried diffusion layer of the one conductivity type, which expands upward at least from an upper surface of the first buried diffusion layer of the one conductivity type; a diffusion layer of the opposite conductivity type, which is formed from a surface of the epitaxial layer, and which is used as a base region; a first diffusion layer of the one conductivity type, which is formed from the surface of the epitaxial layer, and which is used as the collector region; and a second diffusion layer of the one conductivity type, which is formed in the diffusion layer of the opposite conductivity type, and which is used as an emitter region.