Isolated SCR ESD device

Abstract

The present invention discloses an isolated SCR ESD device, comprising: a substrate; a first well located in the substrate, which is floating and has a first conductivity type; a first high density doped region located in the first well and having a second conductivity type; 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; and a third high density doped region located in the second well and having the first conductivity type, wherein the first high density doped region is for electrical connection with a pad, and wherein the first well is not provided with a high density doped region having the first conductivity type for connection with the pad.

1 . 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;   a first high density doped region located in the first well and having a second conductivity type;   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; and   a third high density doped region located in the second well and having the first conductivity type,   wherein the first high density doped region is for electrical connection with a pad, and wherein the first well is not provided with a high density doped region having the first conductivity type for connection with the pad.   
     
     
         2 . The isolated SCR ESD device of  claim 1 , wherein the first high density doped region, the first well, the second well, and the third high density doped region constitute an SCR. 
     
     
         3 . The isolated SCR ESD device of  claim 1 , wherein the first conductivity type is N-type and the second conductivity type is P-type. 
     
     
         4 . The isolated SCR ESD device of  claim 1 , further comprising a fourth high density doped region located at a junction area between the first and second wells. 
     
     
         5 . The isolated SCR ESD device of  claim 4 , wherein the fourth high density doped region is the first or second conductivity type. 
     
     
         6 . The isolated SCR ESD device of  claim 1 , further comprising a fourth high density doped region located in the first well and with a predetermined distance from a junction area between the first and second wells. 
     
     
         7 . The isolated SCR ESD device of  claim 6 , wherein the fourth high density doped region is the first conductivity type. 
     
     
         8 . The isolated SCR ESD device of  claim 1 , further comprising a fourth high density doped region located in the second well and with a predetermined distance from a junction area between the first and second wells. 
     
     
         9 . The isolated SCR ESD device of  claim 8 , wherein the fourth high density doped region is the second conductivity type. 
     
     
         10 . The isolated SCR ESD device of  claim 1 , wherein the second and third high density doped regions are coupled to a grounding pad.