Patent ID: 8278715

Claim:
An electrostatic discharge (ESD) protection structure, comprising: a substrate comprising a first conductive type; a first diffusion region formed in the substrate and comprising a second conductive type; a first doped region formed in the first diffusion region and comprising the first conductive type; a second doped region formed in the first diffusion region and comprising the second conductive type, wherein the second doped region surrounds the first doped region; a third doped region formed in the substrate and comprising the second conductive type; a first isolation region formed in the substrate, covering a portion of the first diffusion region and located between the second and the third doped regions; and a fourth doped region formed in the substrate and comprising the first conductive type, wherein when the first doped region is coupled to a first power line, and the third and the fourth doped regions are coupled to a second power line, an ESD current can be released to the second power line from the first power line, and wherein during the release of the ESD current, the second doped region is not electrically connected to the first power line.