Patent ID: 8710544

Claim:
An isolated silicon controlled rectifier (SCR) electro-static discharge (ESD) device comprising: a substrate; a first well located in the substrate, which is floating and has a first conductivity type, wherein the first well is not included with a high density doped region having the first conductivity type for connection with the pad; a first high density doped region having a second conductivity type for electrical connection with a pad, wherein the first high density doped region is located in the first well; a second well nearby the first well and having the second conductivity type; a second high density doped region located in the second well and having the second conductivity type; a third high density doped region located in the second well and having the first conductivity type, wherein the first high density doped region, the first well, the second well, and the third high density doped region constitute an SCR; and a fourth high density doped region located at one or more of the following locations: (1) at a junction area between the first and second wells, (2) in the first well and with a predetermined distance from the junction area between the first and second wells, or (3) in the second well and with a predetermined distance from the junction area between the first and second wells.