PNP controlled ESD protection device with high holding voltage and snapback
View Patent ↗An ESD protection device protects a circuit from TLPs between a first terminal and a second terminal. The device includes an NPN discharge structure and a PNP triggering device. The first terminal is coupled to the p-doped emitter and the n-doped base of the PNP triggering device and also the n-doped emitter of the NPN discharge structure. The second terminal is coupled to the n-doped collector of the NPN discharge structure. The p-doped collector of the PNP triggering device is coupled to the p-doped base of the NPN discharge structure. A TLP causes base-collector junction breakdown in the PNP triggering device, which results in a current through the PNP triggering device. That current is injected into the base of the NPN discharge structure, which results in a larger discharge current through the NPN discharge structure. The device provides high holding voltage ESD protection device with snapback.
1 . A device, comprising:
an integrated chip having a first terminal, a second terminal, a semiconductor substrate, and an electrostatic discharge (ESD) protection device, the ESD protection device comprising an NPN discharge structure and a PNP triggering device;
wherein the NPN discharge structure comprises an n-doped emitter, a p-doped base, and an n-doped collector, each of which is formed in the semiconductor substrate;
the PNP triggering device comprises a p-doped emitter, an n-doped base, and a p-doped collector, each of which is formed in the semiconductor substrate;
the first terminal is coupled by a first coupling to the p-doped emitter, by a second coupling to the n-doped base, and by a third coupling to the n-doped emitter;
the second terminal is coupled by a fourth coupling to the n-doped collector;
the p-doped collector is coupled by a fifth coupling to the p-doped base; and
the first coupling, the second coupling, the third coupling, the fourth coupling, and the fifth coupling respectively comprise a first, a second, a third, a fourth, and a fifth conductor formed outside the semiconductor substrate.
2 . The device of claim 1 , wherein the first coupling, the second coupling, the third coupling, the fourth coupling, and the fifth coupling each comprise a part of a metal interconnect structure for the integrated chip.
3 . The device of claim 1 , wherein the ESD protection device is structured so that a positive pulse of sufficient magnitude applied between the first terminal and the second terminal causes a junction between the n-doped base and the p-doped collector to break down resulting in a first current from the n-doped base to the p-doped collector, which in turn causes a second current from the p-doped emitter to the p-doped collector that is channeled into the p-doped base and discharges through the n-doped collector, which in turn causes a third current from the n-doped emitter to the n-doped collector.
4 . The device of claim 1 , wherein the p-doped base is floating with respect to the first terminal and the second terminal.
5 . The device of claim 1 , wherein:
the p-doped base is isolated from the first terminal by the n-doped emitter; and
the p-doped base is isolated from the second terminal by the n-doped collector.
6 . The device of claim 1 , wherein a holding voltage for the ESD protection device is determined by a width of the p-doped base.
7 . The device of claim 1 , wherein the p-doped emitter comprises a heavily p-doped contact region that forms a junction with the n-doped base.
8 . The device of claim 1 , wherein:
the n-doped emitter comprises a first heavily n-doped contact region coupled to the first terminal;
the n-doped collector comprises a second heavily n-doped contact region coupled to the second terminal;
the n-doped emitter at a first junction with the p-doped base has a lower N-doping than the first heavily n-doped contact region; and
the n-doped collector at a second junction with the p-doped base has a lower N-doping than the second heavily n-doped contact region.
9 . The device of claim 1 , wherein the second coupling, which is from the first terminal to the n-doped base, comprises a buried n-doped layer within the semiconductor substrate.
10 . The device of claim 1 , wherein the NPN discharge structure and the PNP triggering device occupy distinct areas of the semiconductor substrate.
11 . The device of claim 1 , further comprising:
a PN diode formed in the semiconductor substrate;
wherein the PN diode comprises an n-doped region coupled to the first terminal and a p-doped region coupled to the second terminal; and
the n-doped region provides junction isolation between the second terminal and the p-doped base.
12 . The device of claim 11 , wherein the ESD protection device is structured so that a negative pulse of sufficient magnitude applied between the first terminal and the second terminal is discharged through the PN diode.
13 . The device of claim 11 , wherein the n-doped region overlaps the n-doped base.
14 . The device of claim 11 , wherein the n-doped region overlaps the n-doped emitter.
15 . An integrated chip, comprising:
a semiconductor substrate comprising a first terminal, a second terminal, and an electrostatic discharge (ESD) protection device coupled between the first terminal and the second terminal, the ESD protection device comprising an NPN discharge structure activated by a PNP triggering device;
wherein the NPN discharge structure and the PNP triggering device are formed in the semiconductor substrate;
the NPN discharge structure comprises a first n-doped region and a second n-doped region separated by a p-doped region;
the PNP triggering device comprises a first p-doped region and a second p-doped region separated by an n-doped region; and
a metal interconnect structure disposed above the semiconductor substrate, wherein the metal interconnect structure couples:
the first terminal to the first n-doped region of the NPN discharge structure;
the second terminal to the second n-doped region of the NPN discharge structure;
the p-doped region of the NPN discharge structure to the first p-doped region of the PNP triggering device; and
the second terminal to the n-doped region and the second p-doped region of the PNP triggering device.
16 . The integrated chip of claim 15 , further comprising:
a PN diode formed in the semiconductor substrate;
wherein a p-doped region of the PN diode is coupled to the first terminal; and
an n-doped region of the PN diode is coupled to the second terminal.
17 . The integrated chip of claim 16 , wherein the n-doped region of the PN diode overlaps the n-doped region of the PNP triggering device and the first n-doped region of the NPN discharge structure.
18 . An integrated chip, comprising:
a semiconductor substrate;
an electrostatic discharge protection device comprising an NPN bipolar junction transistor and a PNP bipolar junction transistor, wherein the NPN bipolar junction transistor comprises an n-doped emitter, a p-doped base, and an n-doped collector, and the PNP bipolar junction transistor comprises a p-doped emitter, an n-doped base, and a p-doped collector; and
a metal interconnect structure comprising a first metal structure, a second metal structure, and a third metal structure over the semiconductor substrate, wherein the first metal structure couples an anode terminal to the p-doped emitter, the n-doped base, and the n-doped emitter, the second metal structure couples a cathode terminal to the n-doped collector, and the third metal structure couples the p-doped collector to the p-doped base;
wherein the p-doped collector and the p-doped base are physically separated from one another.
19 . The integrated chip of claim 18 , wherein the NPN bipolar junction transistor surrounds the PNP bipolar junction transistor.
20 . The integrated chip of claim 18 , further comprising a p-doped region in the semiconductor substrate, wherein the second metal structure couples the cathode terminal to the p-doped region.