Electrostatic discharge (ESD) protection device

Abstract

An electrostatic discharge protection device includes a triggered bipolar junction transistor (BJJ) and a silicon controlled rectifier (SCR), coupled between a first conductive pad and a second conductive pad. The triggered BJJ has a first parasitic base-emitter resistance. The SCR includes a first parasitic BJJ and a second parasitic BJJ. The emitter and base of the second parasitic BJJ are respectively coupled to the emitter and base of the triggered BJJ. The second parasitic BJJ has a second parasitic base-emitter resistance smaller than the first parasitic base-emitter resistance. The collector of the triggered BJJ is implemented with a first heavily doped region, and the base of the first parasitic BJJ is implemented with a first doped region, the first doped region being separate from the first heavily doped region.

Claims

1. An electrostatic discharge protection device, comprising: a trigger-type bipolar junction transistor coupled between a first conductive pad and a second conductive pad, wherein the trigger-type bipolar junction transistor has a first parasitic base-emitter resistor; and a silicon controlled rectifier coupled between the first conductive pad and the second conductive pad, wherein the silicon controlled rectifier includes a first parasitic bipolar junction transistor and a second parasitic bipolar junction transistor, the base and collector of the first parasitic bipolar junction transistor are respectively coupled to the collector and base of the second parasitic bipolar junction transistor, the emitter and base of the second parasitic bipolar junction transistor are respectively coupled to the emitter and base of the trigger-type bipolar junction transistor, the second parasitic bipolar junction transistor has a second parasitic base-emitter resistor, the second parasitic base-emitter resistor being smaller than the first parasitic base-emitter resistor; The collector of the triggered bipolar junction transistor is implemented with a first heavily doped region, and the base of the first parasitic bipolar junction transistor is implemented with a first doped region. The first doped region is separate from the first heavily doped region, and the first doped region and the first heavily doped region have the same conductivity.

2. The electrostatic discharge protection device as claimed in claim 1, wherein the base of the first parasitic bipolar junction transistor is electrically floating.

3. The electrostatic discharge protection device as claimed in claim 1, wherein the collector and emitter of the trigger-type bipolar junction transistor are respectively coupled to the first conductive pad and the second conductive pad.

4. The electrostatic discharge protection device as claimed in claim 1, wherein the emitter of the first parasitic bipolar junction transistor and the emitter of the second parasitic bipolar junction transistor are respectively coupled to the first conductive pad and the second conductive pad.

5. The electrostatic discharge protection device as claimed in claim 1, wherein the triggered bipolar junction transistor and the second parasitic bipolar junction transistor are NPN bipolar junction transistors, and the first parasitic bipolar junction transistor is a PNP bipolar junction transistor.

6. The electrostatic discharge protection device as claimed in claim 1, wherein the triggered bipolar junction transistor and the second parasitic bipolar junction transistor are PNP bipolar junction transistors, and the first parasitic bipolar junction transistor is an NPN bipolar junction transistor.

7. The electrostatic discharge protection device as claimed in claim 1, wherein the first doped region and the first heavily doped region have a first conductivity type, the base and emitter of the triggered bipolar junction transistor are respectively implemented by a second doped region and a second heavily doped region, the second doped region having a second conductivity type opposite to the first conductivity type, the second heavily doped region having the first conductivity type, the first heavily doped region and the second heavily doped region being disposed in the second doped region, the emitter and collector of the first parasitic bipolar junction transistor are respectively implemented by a third heavily doped region and a third doped region, the third heavily doped region and the third doped region having the second conductivity type, the first doped region... The third doped region is directly adjacent to the first doped region. The third heavily doped region is located in the first doped region. Both the first heavily doped region and the third heavily doped region are coupled to the first conductive pad. The third doped region is directly adjacent to the second doped region. The base and emitter of the second parasitic bipolar junction transistor are respectively implemented by the third doped region and a fourth heavily doped region. The fourth heavily doped region has the first conductivity type. The fourth heavily doped region and a fifth heavily doped region having the second conductivity type are located in the third doped region. The second heavily doped region and the fifth heavily doped region are separated. The second heavily doped region, the fourth heavily doped region and the fifth heavily doped region are all coupled to the second conductive pad.

8. The electrostatic discharge protection device as claimed in claim 7, wherein the doping concentration of the second doped region is less than or equal to the doping concentration of the third doped region, and the shortest distance between the fourth doped region and the fifth doped region is less than the shortest distance between the second doped region and the fifth doped region.

9. The electrostatic discharge protection device as claimed in claim 7, wherein the doping concentration of the second doped region is less than the doping concentration of the third doped region, and the shortest distance between the fourth doped region and the fifth doped region is less than or equal to the shortest distance between the second doped region and the fifth doped region.

10. The electrostatic discharge protection device as claimed in claim 1, wherein a positive electrostatic discharge voltage is applied to the first conductive pad, and when the second conductive pad is grounded, the trigger-type bipolar junction transistor, the second parasitic bipolar junction transistor, and the first parasitic bipolar junction transistor are sequentially turned on.

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