Patent ID: 8785971
Filing Date: 2014-07-22
Classification: H01L

Abstract:
1. A transient voltage suppressor without leakage current, comprising: a P-type substrate; an N-type epitaxial layer formed on said P-type substrate, and a first N-type heavily doped area and a first P-type heavily doped area are formed in said N-type epitaxial layer; a first N-type buried area formed in a bottom of said N-type epitaxial layer to neighbor said P-type substrate and located below said first N-type heavily doped area and said first P-type heavily doped area; an electrostatic discharge (ESD) device formed in said N-type epitaxial layer and coupled to said first N-type heavily doped area; at least one deep isolation trench formed in said N-type epitaxial layer, having a depth greater than a depth of said first N-type buried area, and being adjacent to said first N-type buried area to separate said first N-type buried area and said ESD device; a clamp P-type well formed in said N-type epitaxial layer, and a second N-type heavily doped area is formed in said clamp P-type well; a third N-type heavily doped area formed in said N-type epitaxial layer and coupled to said first and second N-type heavily doped areas; a second P-type heavily doped area formed in said N-type epitaxial layer; a second N-type buried area, together with said first N-type buried area, located on a horizontal plane and formed in said bottom of epitaxial layer to neighbor said P-type substrate, wherein said second N-type buried area is located below said third N-type heavily doped area and said second P-type heavily doped area; a fourth N-type heavily doped area formed in said N-type epitaxial layer, wherein said fourth N-type heavily doped area and said first P-type heavily doped area are coupled to a first I/O pin; a fifth N-type heavily doped area formed in said N-type epitaxial layer, wherein said fifth N-type heavily doped area and said second P-type heavily doped area are coupled to a second I/O pin, and wherein said depth of said deep isolation trench is greater than a depth of said second N-type buried area, and wherein said deep isolation trench is further adjacent to said second N-type buried area to separate said first and second N-type buried areas, said clamp P-type well and said fourth and fifth N-type heavily doped areas; and a second P-type well formed in said N-type epitaxial layer and located above said second N-type buried area, wherein said third N-type heavily doped area is formed in said second P-type well.