US5268588A
Expired / Lapsed
US
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Semiconductor structure for electrostatic discharge protection
Assignee: Texas Instruments Inc
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Filing: 1992-09-30
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Granted: 1993-12-07
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Expires: 2012-09-30
Abstract
Abstract A semiconductor structure (30) is provided for electrostatic discharge protection. A first bipolar transistor (Q1) has a collector electrically coupled to a first node (12), a base electrically coupled to a second node, and an emitter electrically coupled to a third node (14). A second bipolar transistor (Q2) has a collector, a base electrically coupled to the second node, and an emitter electrically coupled to the first node (14). The second bipolar transistor (Q2) supplies a base current to the base of the first bipolar transistor (Q1) in response to the first node (12) reaching a threshold voltage relative to the third node (14), so that the first bipolar transistor (Q1) conducts current between the first (12) and third (14) nodes in response to the base current.
Inventors
- 👤 Steven E. Marum
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 14:33
CPC Classifications
H; H10; H10D; H10D89/00; H10D89/60; H10D89/601
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
207 words
A structure for electrostatic discharge protection, comprising: a first semiconductor layer having a first conductivity type; a heavily doped semiconductor layer having a second conductivity type opposite said first conductivity type, disposed over said first semiconductor layer; a second semiconductor layer having said second doped semiconductor layer; first and second heavily doped regions having said second conductivity type, formed laterally within said face to contact said heavily doped semiconductor layer and electrically coupled to a first node; a lightly doped region having said first conductivity type formed laterally within said face to be interposed between said first and second heavily doped regions; third and fourth heavily doped regions having said second conductivity type, formed laterally within said lightly doped region and electrically coupled to said first node; fifth and sixth heavily doped regions having said second conductivity type, formed laterally within said lightly doped region to be interposed between said third and fourth heavily doped regions; and a seventh heavily doped region having said first conductivity type, formed laterally within said lightly doped region to be interposed between said fifth and sixth heavily doped regions and electrically coupled to a second node, wherein said fifth and sixth heavily doped regions are electrically coupled to a third node.
Claim 2
Dependent Claim
207 words
A structure for electrostatic discharge protection, comprising: a first semiconductor layer having a first conductivity type; a heavily doped semiconductor layer having a second conductivity type opposite said first conductivity type, disposed over said first semiconductor layer; a second semiconductor layer having said second doped semiconductor layer; first and second heavily doped regions having said second conductivity type, formed laterally within said face to contact said heavily doped semiconductor layer and electrically coupled to a first node; a lightly doped region having said first conductivity type formed laterally within said face to be interposed between said first and second heavily doped regions; third and fourth heavily doped regions having said second conductivity type, formed laterally within said lightly doped region and electrically coupled to said first node; fifth and sixth heavily doped regions having said second conductivity type, formed laterally within said lightly doped region to be interposed between said third and fourth heavily doped regions; and a seventh heavily doped region having said first conductivity type, formed laterally within said lightly doped region to be interposed between said fifth and sixth heavily doped regions and electrically coupled to a second node, wherein said fifth and sixth heavily doped regions are electrically coupled to a third node.
Claim 3
Dependent Claim
73 words
The structure of claim 1 wherein an emitter of a first bipolar transistor is formed by said fifth and sixth heavily doped regions, wherein a base of said first bipolar transistor is formed by said lightly doped region and said seventh heavily doped region, and wherein a collector of said first bipolar transistor is formed by said heavily doped semiconductor layer, said second semiconductor layer, and said first and second heavily doped regions.
Claim 4
Dependent Claim
73 words
The structure of claim 2 wherein an emitter of a second bipolar transistor is formed by said third and fourth heavily doped regions, wherein a base of said second bipolar transistor is formed by said lightly doped region and said seventh heavily doped region, and wherein a collector of said second bipolar transistor is formed by said heavily doped semiconductor layer, said second semiconductor layer, and said first and second heavily doped regions.
Claim 5
Dependent Claim
57 words
The structure of claim 3 wherein said second bipolar transistor supplies a base current to said base of said first bipolar transistor in response to said first node reaching a threshold voltage relative to said third node, so that said first bipolar transistor conducts current between said first and third nodes in response to said base current.
Claim 6
Dependent Claim
35 words
The structure of claim 4 wherein said second bipolar transistor operates as a reverse biased emitter-base junction for breaking down and providing said base current in response to said first node reaching said threshold voltage.
Claim 7
Dependent Claim
20 words
The structure of claim 4 wherein said threshold voltage is lower than a breakdown voltage of said first bipolar transistor.
Claim 8
Dependent Claim
16 words
The structure of claim 1 wherein said first node is electrically coupled to an output pad.
Claim 9
Dependent Claim
21 words
The structure of claim 1 wherein said second node is electrically coupled to circuitry to be protected against an electrostatic discharge.
Claim 10
Dependent Claim
14 words
The structure of claim 1 wherein said third node comprises a voltage reference node.
Claim 11
Dependent Claim
105 words
The structure of claim 1 and further comprising: at least one first additional lightly doped region having said first conductivity type formed laterally within said face to be interposed between said first heavily doped region and said fifth heavily doped region; and at least one second additional lightly doped region having said first conductivity type formed laterally within said face to be interposed between said second heavily doped region and said sixth heavily doped region, each of said first and second additional lightly doped regions having a corresponding heavily doped region formed therein having said first conductivity type and electrically coupled to said first node.
Claim 12
Dependent Claim
163 words
The structure of claim 10, wherein said first conductivity type is P and said second conductivity type is N, and wherein: an emitter of a first npn bipolar transistor is formed by said fifth and sixth heavily doped regions, wherein a base of said first npn bipolar transistor is formed by said lightly doped region and said seventh heavily doped region, and wherein a collector of said first npn bipolar transistor is formed by said heavily doped semiconductor layer, said second semiconductor layer, and said first and second heavily doped regions; and wherein an emitter of a second npn bipolar transistor is formed by said third and fourth heavily doped regions, wherein a base of said second npn bipolar transistor is formed by said lightly doped region and said seventh heavily doped region, and wherein a collector of said second npn bipolar transistor is formed by said heavily doped semiconductor layer, said second semiconductor layer, and said first and second heavily doped regions.
Claim 13
Dependent Claim
84 words
The structure of claim 11 wherein a collector of a pnp bipolar transistor is formed by said lightly doped region and said seventh heavily doped region, wherein an emitter of said pnp bipolar transistor is formed by each of said first and second additional lightly doped regions and said corresponding heavily doped regions formed therein, and wherein a base of said pnp bipolar transistor is formed by said heavily doped semiconductor layer, said second semiconductor layer, and said first and second heavily doped regions.
Claim 14
Dependent Claim
60 words
The structure of claim 12 wherein said second npn bipolar transistor supplies a base current to said base of said first npn bipolar transistor in response to said first node reaching a threshold voltage relative to said third node, so that said first npn bipolar transistor conducts current between said first and third nodes in response to said base current.
Claim 15
Dependent Claim
49 words
The structure of claim 13 wherein said first npn bipolar transistor and said pnp bipolar transistor together form a silicon controlled rectifier, such that a voltage at said first node initially decreases in response to said first bipolar transistor beginning to conduct current between said first and third nodes.
Claim 16
Dependent Claim
55 words
The structure of claim 14 wherein a holding current of said silicon controlled rectifier is adjustable in response to a spacing between said first heavily doped region and each said first additional lightly doped region, and in response to a spacing between said second heavily doped region and each said second additional lightly doped region.
Claim 17
Dependent Claim
15 words
The structure of claim 1 wherein said second semiconductor layer comprises an epitaxial semiconductor layer.
Claim 18
Dependent Claim
27 words
The structure of claim 1 wherein said first semiconductor layer has a face at which said heavily doped semiconductor layer is formed in said first semiconductor layer.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1996-12-06 | 1997-06-07 | 1997-12-07 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2000-12-06 | 2001-06-07 | 2001-12-07 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2004-12-06 | 2005-06-07 | 2005-12-07 | $7700.00 | Window Closed / Lapsed |