Patent ID: 7012305
Filing Date: 2006-03-14
Classification: H01L

Abstract:
1. An electro-static discharge (ESD) protection circuit for a dual polarity input/output (I/O) pad, comprising: a substrate of a first conductive type; a deep well region of a second conductive type, disposed in the substrate of the first conductive type; a well region of the first conductive type, disposed in the deep well region of the second conductive type; a first transistor, disposed over the well region of the first conductive type, wherein the first transistor comprises a first gate, a first source and a first drain; a second transistor, disposed over the substrate of the first conductive type, wherein the second transistor comprises a second gate, a second source and a second drain, wherein the second source and the first drain are a common-use doped region, and the common-use doped region is overlapping with the deep well region, the well region, and a portion of the substrate other than the deep well region; a first doped region with the first conductive type, disposed in the well region of first conductive type and laterally adjacent to the first source, wherein the first doped region, the first source and the first gate are electrically connected to an input pad; and a second doped region with the first conductive type, disposed in the substrate of the first conductive type and laterally adjacent to the second drain, wherein the second doped region, the second drain and the second gate are electrically connected to an output pad.