Patent ID: 8304838

Claim:
A electrostatic discharge (ESD) protection device structure, comprising: a semiconductor substrate; an N-type epitaxial layer arranged on said semiconductor substrate; and at least one snapback cascade structure arranged in said N-type epitaxial layer, wherein said snapback cascade structure further comprises: a first P-type well arranged in said N-type epitaxial layer, wherein a first heavily doped area and a second heavily doped area are arranged in said first P-type well, and wherein said first heavily doped area and said second heavily doped area respectively belong to opposite types; and a second P-type well arranged in said N-type epitaxial layer, wherein a third heavily doped area and a fourth heavily doped area are arranged in said second P-type well, and wherein said third heavily doped area and said fourth heavily doped area respectively belong to opposite types, and wherein said second heavily doped area and said third heavily doped area respectively belong to opposite types and are electrically connected with each other, wherein when said first heavily doped area receives an ESD signal, an ESD current flows from said first heavily doped area to said fourth heavily doped area through said first P-type well, said N-type epitaxial layer, and said second P-type well.