Patent ID: 8097920

Claim:
A semiconductor integrated circuit device comprising an electro static discharge protection element, the electro static discharge protection element being formed by a diode including: a well region of a first conductivity type in a semiconductor substrate; and a first diffusion layer of a second conductivity type in the well region, wherein the first diffusion layer is surrounded by a second diffusion layer of the first conductivity type in the well region, the first diffusion layer has a surface on which a first contact region connected to an input/output terminal is formed, and the second diffusion layer has a surface on which a second contact region connected to a reference voltage terminal is formed, the first diffusion layer has a rectangular shape whose sides are each formed linearly when viewed in plan, a dielectric isolation region is formed between the first diffusion layer and the second diffusion layer to surround an entire periphery of the first diffusion layer, and the second contact region is formed on portions of the second diffusion layer facing a long side and a short side of the first diffusion layer.