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Patent US4559696A successfully refreshed from Google Patents.
US4559696A
Expired / Lapsed
US
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Ion implantation to increase emitter energy gap in bipolar transistors
Assignee: National Semiconductor Corp
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Filing: 1984-07-11
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Granted: 1985-12-24
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Expires: 2004-07-11
Abstract
Abstract The suppression of the reverse injection of the carriers in a bipolar transistor, without adversely effecting forward injection, is carried out by modifying the energy gap characteristics of the transistor so that a greater barrier to reverse injection is presented than that which is confronted by the forward injected carriers. The energy gap of the emitter is increased, relative to that of the base, through ion implantation. The ions which are implanted are such that the resulting compound material has a higher energy gap than that of silicon into which they are implanted to selectively modify the emitter region so as to locally increase its energy gap. Preferred materials include carbon and nitrogen.
Inventors
- 👤 Kranti Anand
- 👤 Robert J. Strain
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 03:37
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/202; H10P30/204; H10D; H10D10/00; H10D10/80; H10D10/821; H10D10/861; H10D62/00; H10D62/80; H10D62/83; H10D62/834; H10P30/208; H10P30/21
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
93 words
A method of improving the emitter efficiency of a bipolar transistor, comprising the steps of: doping a silicon substrate with an impurity of one conductivity to form a base region for a transistor; implanting an impurity of opposite conductivity in a portion of said base region to form an emitter region; and implanting ions of a material having an energy gap which is greater than the energy gap of silicon in said emitter region, thereby to provide the emitter region with an energy gap which is greater than that of the base region.
Claim 2
Independent Claim
93 words
A method of improving the emitter efficiency of a bipolar transistor, comprising the steps of: doping a silicon substrate with an impurity of one conductivity to form a base region for a transistor; implanting an impurity of opposite conductivity in a portion of said base region to form an emitter region; and implanting ions of a material having an energy gap which is greater than the energy gap of silicon in said emitter region, thereby to provide the emitter region with an energy gap which is greater than that of the base region.
Claim 3
Dependent Claim
10 words
The method of claim 1 wherein said material is carbon.
Claim 4
Dependent Claim
10 words
The method of claim 1 wherein said material is nitrogen.
Claim 5
Dependent Claim
14 words
The method of claim 1 wherein said two implanting steps are carried out simultaneously.
Claim 6
Dependent Claim
14 words
The method of claim 1 wherein said implanting steps are carried out in succession.
Claim 7
Dependent Claim
101 words
In a bipolar transistor having an emitter region of one conductivity located adjacent a base region of opposite conductivity, a method for providing reduced conduction by injection of carriers from the base region to the emitter region, relative to the injection of carriers from the emitter region to the base region, comprising the step of implanting the emitter region with ions of a material having an energy gap which is greater than the energy gap of the substrate in which the transistor is formed, thereby to increase the energy gap of the emitter region relative to that of the base region.
Claim 8
Dependent Claim
101 words
In a bipolar transistor having an emitter region of one conductivity located adjacent a base region of opposite conductivity, a method for providing reduced conduction by injection of carriers from the base region to the emitter region, relative to the injection of carriers from the emitter region to the base region, comprising the step of implanting the emitter region with ions of a material having an energy gap which is greater than the energy gap of the substrate in which the transistor is formed, thereby to increase the energy gap of the emitter region relative to that of the base region.
Claim 9
Dependent Claim
27 words
The process of claim 6 wherein the transistor is formed on a silicon substrate and said material has an energy gap that is greater than 1.1 eV.
Claim 10
Dependent Claim
37 words
The process of claim 6 wherein said transistor is embodied in integrated injection logic, and the emitter region with the increased energy gap comprises the uniform n-substrate common to the switching and injection transistors of the logic.
Claim 11
Dependent Claim
10 words
The process of claim 7 wherein said material is carbon.
Claim 12
Dependent Claim
10 words
The process of claim 7 wherein said material is nitrogen.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-12-23 | 1989-06-24 | 1989-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-12-23 | 1993-06-24 | 1993-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-12-23 | 1997-06-24 | 1997-12-24 | $7700.00 | Window Closed / Lapsed |