Electrostatic discharge protection device
AssigneeNEC Electronics Corporation
InventorNoriyuki Kodama
Life of this patent
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Abstract
An N well is formed in a surface of a P+ substrate and a P well is formed in such a way as to surround the N well. Then, a trigger tap (P+ diffusion region) is formed in the surface of the P well and two cathodes (N+ diffusion regions) are formed in such a way as to hold the trigger tap. Then, an anode (P+ diffusion region) is formed in the surface of the N well in a position facing the trigger tap and the cathode, and an N well pick-up diffusion (N+ diffusion region) is formed in such a way as to surround that side edge of the anode which does not face the cathode. Accordingly, the resistance between the end portion of the anode and the N well pick-up diffusion (N+ diffusion region) becomes lower than the resistance between the center portion of the anode and the N well pick-up diffusion.
Claims16
An electrostatic discharge protection device for protecting an internal circuit against electrostatic discharge applied externally, comprising:
- an input pad connected to outside and said internal circuit;
- a trigger circuit which is connected to said input pad and in which a current flows when a voltage applied from said input pad exceeds a predetermined value;
- a first conductivity type semiconductor substrate;
- a second conductivity type well formed in a surface of said first conductivity type semiconductor substrate;
- a first first conductivity type diffusion region formed in that region of said surface of said first conductivity type semiconductor substrate which excludes said second conductivity type well and connected to said trigger circuit;
- a first second conductivity type diffusion region formed apart from both said second conductivity type well and said first first conductivity type diffusion region in said surface of said first conductivity type semiconductor substrate and connected to a reference potential electrode;
- a second first conductivity type diffusion region formed in a surface of said second conductivity type well and connected to said input pad;
- and
- second second conductivity type diffusion region formed in said surface of said second conductivity type well and connected to said input pad, a distance between said second first conductivity type diffusion region and said second second conductivity type diffusion region is non-uniform in a first direction orthogonal to a direction extending toward said second second conductivity type diffusion region from said second first conductivity type diffusion region.
Dependencies are inferred from the claim text.