Patent ID: 8106514

Claim:
A semiconductor device with a first device region and a second device region, comprising: a semiconductor substrate; an insulating interlayer formed on said semiconductor substrate; and an annular guard ring consisting of a conductive film buried in said insulating interlayer and surrounding the periphery of said first device region, wherein a nonconducting part blocking electric conduction in a path from said first device region, through said annular guard ring to said second device region is formed in a guard ring forming region, wherein a first diffusion layer having an opposite conductivity type to a conductivity type of said semiconductor substrate is provided near a surface of said semiconductor substrate, said annular guard ring is connected to a surface of said first diffusion layer, a junction plane in said first diffusion layer constitutes said nonconducting part, wherein said first diffusion layer is apart from second diffusion layers provided in said first device region and said second device region, and wherein said semiconductor device further comprises a well formed in said semiconductor substrate and having a same conductivity type as a conductivity type of said semiconductor substrate in said first device region and said second device region, and said second diffusion layers are other wells formed in said semiconductor substrate and having an opposite conductivity type to a conductivity type of said semiconductor substrate in said first device region and said second device region, wherein both said first device region and said second device region are surrounded by an inner surface of said annular guard ring.