Semiconductor integrated circuit

Abstract

An electro static discharge protection element being formed by a diode including a well region of a first conductivity type on a surface of a semiconductor substrate, and a first diffusion layer of a second conductivity type in the well region. 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. The first diffusion layer has a surface on which a second contact region connected to a reference voltage terminal is formed.

1 . 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.   
     
     
         2 . The semiconductor integrated circuit device of  claim 1 , wherein
 a dielectric isolation region is formed between the first diffusion layer and the second diffusion layer.   
     
     
         3 . The semiconductor integrated circuit device of  claim 1 , wherein
 the first diffusion layer is rectangular in shape, and   the second contact region is formed only in a portion facing a long side of the first diffusion layer.   
     
     
         4 . The semiconductor integrated circuit device of  claim 3 , wherein the second contact region has end portions arranged in a position in alignment with end portions of the first contact region formed along a longitudinal direction of the first diffusion layer. 
     
     
         5 . The semiconductor integrated circuit device of  claim 1 , wherein
 the first diffusion layer is rectangular in shape, and   the first contact region formed along a longitudinal direction of the first diffusion layer has end portions which are greater in area than the other portions of the first contact region.   
     
     
         6 . The semiconductor integrated circuit device of  claim 1 , wherein
 the first diffusion layer is rectangular in shape, and   a width of the second diffusion layer facing a short side of the first diffusion layer is narrower than a width of the second diffusion layer facing a long side of the first diffusion layer.   
     
     
         7 . The semiconductor integrated circuit device of  claim 1 , wherein
 the first diffusion layer is rectangular in shape, and   a distance between the first diffusion layer and the second diffusion layer along a long side of the first diffusion layer is narrower than a distance between the first diffusion layer and the second diffusion layer along a short side of the first diffusion layer.   
     
     
         8 . The semiconductor integrated circuit device of  claim 1 , wherein
 the first diffusion layer is formed into a plurality of divided diffusion regions, and   the second diffusion layer is formed also between the divided diffusion regions.   
     
     
         9 . The semiconductor integrated circuit device of  claim 8 , wherein the divided diffusion regions are arranged at a regular interval. 
     
     
         10 . The semiconductor integrated circuit device of  claim 1 , wherein the first contact region and the second contact region are respectively formed into a plurality of divided contact regions.