US Patent 7109533 Electrostatic discharge protection device

There is provided an electrostatic discharge protection device comprising a P conductive type first P well region 101 formed in a P type epitaxial layer 31 being deposited on a surface of a P+ substrate 30 having a prescribed thickness, an N conductive type first N well 101 a periphery thereof being brought into direct contact with and surrounded by a first P well region 101, P conductive type first P diffusion regions 121a and 121b, a P conductive type third P diffusion region 125, and an N conductive type second N diffusion region 223 arranged within a first P well region 101, and a P conductive type second P diffusion region 123 and an N conductive type first N diffusion region 221 arranged within a first N well 201.