ESD protection structure and method
First Claim
1. A dual-diode electrostatic discharge protection device comprising:
- a) a semiconductor substrate;
b) a first diode formed in said semiconductor substrate, the first diode including;
i) a first well formed in said semiconductor substrate, the first well comprising a first diode cathode;
ii) a first diffusion formed in the first well, the first diffusion comprising a first diode anode, c) a second diode formed in said semiconductor substrate, the second diode including;
i) a second well formed in said semiconductor substrate, ii) a second diffusion formed in the second well, the second well and the second diffusion comprising a second diode cathode and said semiconductor substrate comprising a second diode anode;
d) at least one implant formed at an edge of the first well;
e) at least one implant formed at an edge of the second well; and
f) an input, the input coupled to the first diffusion and said second diffusion and to a protected device such that the protected device is protected from electrostatic discharge; and
wherein said semiconductor substrate comprises a p-type substrate, wherein said first well comprises a n-type well, wherein said first diffusion comprises a p-type diffusion, wherein the at least one implant formed at an edge of the first well comprises a n-type implant, wherein the second well comprises a n-type well, wherein the second diffusion comprises a n-type diffusion, and wherein the at least one implant formed at an edge of the second well comprises a n-type implant.
1 Assignment
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Accused Products
Abstract
The preferred embodiment of the present invention overcomes the limitations of the prior art and provides a device and method to increase the robustness of electrostatic discharge (ESD) protection devices by reducing the temperature gradient caused by ESD pulses and reducing the likelihood of thermal runaway caused by large ESD pulses. The preferred embodiment forms implants under the trench isolation structures in the ESD devices. The implants reduce the current-caused heating that can lead to thermal runaway, and thus improve the robustness of the ESD protection device. In the preferred embodiment, the implants are formed using hybrid resist. The hybrid resist provides a method to form that implants that does not require additional masking steps or other excessive processing. Additionally, the hybrid resist provides implants that are self aligned with the well regions.
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Citations
15 Claims
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1. A dual-diode electrostatic discharge protection device comprising:
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a) a semiconductor substrate;
b) a first diode formed in said semiconductor substrate, the first diode including;
i) a first well formed in said semiconductor substrate, the first well comprising a first diode cathode;
ii) a first diffusion formed in the first well, the first diffusion comprising a first diode anode, c) a second diode formed in said semiconductor substrate, the second diode including;
i) a second well formed in said semiconductor substrate, ii) a second diffusion formed in the second well, the second well and the second diffusion comprising a second diode cathode and said semiconductor substrate comprising a second diode anode;
d) at least one implant formed at an edge of the first well;
e) at least one implant formed at an edge of the second well; and
f) an input, the input coupled to the first diffusion and said second diffusion and to a protected device such that the protected device is protected from electrostatic discharge; and
wherein said semiconductor substrate comprises a p-type substrate, wherein said first well comprises a n-type well, wherein said first diffusion comprises a p-type diffusion, wherein the at least one implant formed at an edge of the first well comprises a n-type implant, wherein the second well comprises a n-type well, wherein the second diffusion comprises a n-type diffusion, and wherein the at least one implant formed at an edge of the second well comprises a n-type implant.
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2. A dual-diode electrostatic discharge protection device comprising:
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a) a semiconductor substrate;
b) a first diode formed in said semiconductor substrate, the first diode including;
i) a first well formed in said semiconductor substrate the first well comprising a first diode cathode;
ii) a first diffusion formed in the first well, the first diffusion comprising a first diode anode;
c) a second diode formed in said semiconductor substrate, the second diode including;
i) a second well formed in said semiconductor substrate, ii) a second diffusion formed in the second well, the second well and the second diffusion comprising a second diode cathode and said semiconductor substrate comprising a second diode anode;
d) at least one implant formed at an edge of the first well;
e) at least one implant formed at an edge of the second well;
f) an input, the input coupled to the first diffusion and said second diffusion and to a protected device such that the protected device is protected from electrostatic discharge;
g) at least one isolation region formed in said first well; and
h) at least one implant formed under said isolation region in said first well. - View Dependent Claims (3, 4, 12)
i) an isolation region formed between said first n-well and said second n-well;
j) a first p-well formed under said isolation region between said first n-well and said second n-well;
k) at least one p+ implant formed at an edge of said first p-well.
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5. A dual-diode electrostatic discharge protection device comprising:
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a) a semiconductor substrate;
b) a first diode formed in said semiconductor substrate the first diode including;
i) a first well formed in said semiconductor substrate the first well comprising a first diode cathode;
ii) a first diffusion formed in the first well the first diffusion comprising a first diode anode;
c) a second diode formed in said semiconductor substrate the second diode including;
i) a second well formed in said semiconductor substrate, ii) a second diffusion formed in the second well the second well and the second diffusion comprising a second diode cathode and said semiconductor substrate comprising a second diode anode;
d) at least one implant formed at an edge of the first well;
e) at least one implant formed at an edge of the second well;
f) an input the input coupled to the first diffusion and said second diffusion and to a protected device such that the protected device is protected from electrostatic discharge;
g) an isolation region formed between said first well and said second well;
h) a third well formed under said isolation region between said first well and said second well;
i) at least one implant formed at an edge of said third well. - View Dependent Claims (6, 7, 8, 9, 10)
g) a fourth well formed in said semiconductor substrate;
h) a fourth diffusion formed in said fourth well, said fourth diffusion coupled to a high potential; and
i) at least one implant formed at an edge of said fourth well.
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8. The dual-diode electrostatic discharge protection device of claim 7 further comprising
j) an isolation region formed between said fourth well and sand second well; -
k) a fifth well formed under said isolation region formed between said fourth well and said second well;
l) at least one implant formed at an edge of said fifth well, the at least one implant formed at an edge of said fifth well combing with said at least one implant formed at an edge of said fourth well and with said at least one implant formed at an edge of said second well to form a buried diode.
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9. The dual-diode electrostatic discharge protection device of claim 7 wherein said semiconductor substrate comprises a p-type substrate, wherein said first well comprises a n-type well, wherein said first diffusion comprises a p-type diffusion, wherein the at least one implant formed at an edge of the first well comprises a n-type implant, wherein the second well comprises a n-type well, wherein the second diffusion comprises a n-type diffusion, wherein the at least one implant formed at an edge of the second well comprises a n-type implant, wherein the fourth well comprises a n-type well, wherein the fourth diffusion comprises an n-type diffusion, and wherein the at least one implant formed at an edge of said forth well comprises an n-type implant.
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10. The dual-diode electrostatic discharge protection device of claim 7 wherein said semiconductor substrate comprises a p-type substrate, wherein said first well comprises a n-type well, wherein said first diffusion comprises a p-type diffusion, wherein the at least one implant formed at an edge of the first well comprises a n-type implant, wherein the second well comprises a n-type well, wherein the second diffusion comprises a n-type diffusion, wherein the at least one implant formed at an edge of the second well comprises a n-type implant, wherein the fourth well comprises a n-type well;
- wherein the fourth diffusion comprises an n-type diffusion, wherein the at least one implant formed at an edge of said forth well comprises an n-type implant, wherein the fifth well comprises a p-type well, and wherein the at least one implant formed at an edge of said fifth well comprises a p-type implant.
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11. A dual-diode electrostatic discharge protection device comprising:
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a) a p-type semiconductor substrate;
b) a first diode formed in said semiconductor substrate, the first diode including;
i) a first n-well formed in said semiconductor substrate, the first well comprising a first diode cathode;
ii) a first p+ diffusion formed in the first well, the first diffusion comprising a first diode anode;
c) a second diode formed in said semiconductor substrate, the second diode including;
i) a second n-well formed in said semiconductor substrate;
ii) a first n+ diffusion formed in the second well, the second n-well and the first n+ diffusion comprising a second diode cathode and said semiconductor substrate comprising a second diode anode;
d) at least one n+ implant formed at an edge of the first well;
e) at least one n+ implant formed at an edge of the second well, f) at least one isolation region formed in said first n-well;
g) a n+ diffusion formed in said first n-well between said isolation region and one of said at least one implant formed at an edge of the first n-well, and wherein said n+ diffusion is coupled to a high potential;
h) an input, the input coupled to the fist diffusion and said second diffusion and to a protected device such that the protected device is protected from electrostatic discharge. - View Dependent Claims (13, 14)
i) a third n-well formed in said semiconductor substrate;
j) a second n+ diffusion formed in said third n-well well, said second n+ diffusion coupled to a high potential; and
k) at least one n+ implant formed at an edge of said third n-well.
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14. The dual-diode electrostatic discharge protection device of claim 13 further comprising:
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l) an isolation region formed between said third n-well and said second n-well;
o) a second p-well formed under said isolation region formed between said third n-well and said second n-well; and
q) at least one p+ implant formed at an edge of said second p-well, the at least one p+ implant formed at an edge of said second p-well combing with said at least one n+ implant formed at an edge of said third n-well and with said at least one n+ implant formed at an edge of said second n-well to form a buried diode.
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15. A dual-diode electrostatic discharge protection device comprising:
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a) a p-type semiconductor substrate;
b) a first diode formed in said semiconductor substrate, the first diode including;
i) a first n-well formed in said semiconductor substrate, the first n-well comprising a first diode cathode;
ii) a first p+ diffusion formed in the first well, the first p+ diffusion comprising a first diode anode;
c) a second diode formed in said semiconductor substrate, the second diode including;
i) a second n-well formed in said semiconductor substrate;
ii) a first n+diffusion formed in the second n-well, the second n-well and the second n+ diffusion comprising a second diode cathode and said semiconductor substrate comprising a second diode anode;
d) at least one n+implant formed at an edge of the first n-well;
e) at least one n+implant formed at an edge of the second n-well;
f) at least one isolation region formed in said first n-well;
g) a n+ diffusion formed in said first n-well between said isolation region and one of said at least one implant formed at an edge of the first n-well, and wherein said n+ diffusion is coupled to a high potential;
h) at least one n+ implant formed under said isolation region in said first n-well;
i) an isolation region formed between said first n-well and said second n-well;
j) a first p-well formed under said isolation region between said first n-well and said second n-well;
k) at least one p+ implant formed at an edge of said first p-well;
l) a third n-well formed in said semiconductor substrate;
m) a second n+ diffusion formed in said third n-well, said second n+ diffusion coupled to a high potential;
n) at least one n+ implant formed at an edge of said third n-well;
o) an isolation region formed between said third n-well and said second n-well;
p) a second p-well formed under said isolation region formed between said third n-well and said second n-well;
q) at least one p+ implant formed at an edge of said second p-well, the at least one p+ implant formed at an edge of said second p-well combing with said at least one n+ implant formed at an edge of said third n-well and with said at least one n+ implant formed at an edge of said second n-well to form a buried diode; and
r) an input, the input coupled to the first diffusion and said second diffusion and to a protected device such that the protected device is protected from electrostatic discharge.
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Specification