US3856578A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Bipolar transistors and method of manufacture
Assignee: AT&T Inc
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Filing: 1973-07-16
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Granted: 1974-12-24
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Expires: 1993-07-16
Abstract
Abstract A bipolar transistor is fabricated by a process which involves a two-step base formation and an emitter formed by diffusion or ion implantation. One processing step in forming the base is either a diffusion or ion implantation of impurities which step primarily determines sheet resistivity. The other processing step is an ion implantation which primarily determines doping concentration under the emitter. The resulting composite doping profile has at least one point of inflection and is dominated at the surface region by the impurities introduced by the former step and in the bulk by the impurities introduced by the latter step. The emitter is preferably implanted and then diffused to a depth which locates the emitter-base junction past the portion of the base profile dominated by the impurities determining sheet resistivity.
Inventors
- 👤 R Payne
- 👤 R Scavuzzo
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 03:47
CPC Classifications
H; H10; H10P; H10P30/00; H10P30/20; H10P30/202; H10P30/204; H10P30/21; H10P30/212; H10P30/28; Y; Y10; Y10S; Y10S148/00; Y10S148/04; Y10S148/041; Y10S148/067; Y10S148/145; Y10S148/151
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
266 words
A METHOD OF FABRICATING A TRANSISTORR COMPRISING THE STEPS OF: EXPOSING A SEMICONDUCTOR ZONE OF ONE CONDUCTIVITY TYPE TO A FIRST ION BEAM OF IMPURITIES OF OPPOSSITE CONDUCTIVITY TYPPE SO AS TO FORM A FIRST REGION OF IMPURITIES OF OPPOSITE CONDUCTIVITY TYPE THEREIN; EXPOSING SAID ZONE TO A SECOND ION BEAM OF IMPURITIES OF SAID OPPOSITE CONDUCTIVITY TYPE SO AS TO FORM A SECOND REGION OF IMPURITIES OF OPPOSITE CONDUCTIVITY TYPE THEREIN OVER THE AREA OF THE FIRST REGION WITH A PEAK DENSITY WHICH IS LESS THAN THE PEAK DENSITY OF THE FIRST REGION AND WHICH EXTENDS DEEPER INTO SAID ZONE THAN THE PEAK DENSITY OF THE FIRST REGION, SAID FIRST AND SECOND REGIONS OF IMPURITIES OVERLAPPING TO FORM A COMPOSITE REGION OF IMPURITIES COMPRISING THE BASE REGION WHICH IS DOMINATED BY THE IMPURITIES OF THE FIRST REGION FROM THE SURFACE OF THE BODY TO A DEPTH LESS THAN X1 AND WHICH IS DOMINATED BY THE IMPURITIES OF THE SECOND REGION AT A DEPTH GREATER THAN X1 AND FURTHER WHEREIN THERE EXISTS AT LEAST ONE POINT OF INFLECTION IN THE IMPURITY PROFILE OF THE COMPOSITE REGION; AND, FOLLOWING THE FORMATION OF SAID BASE REGION, FORMING AN EMITTER REGION OF IMPURITIES OF SAID ONE CONNDUCTIVITY TYPE WITHIN THE SEMICONDUCTOR ZONE WITHIN THE AREA DEFINED BY SAID BASE REGION BY EXPOSING SAID ZONE TO A THIRD ION BEAM OF IMPURITIES OF SAID ONE CONDUCTIVITY TYPE AND SUBSEQUENTLY HEATING SAID ZONE TO DIFFUSE THE IMPURITIES FURTHER INTO THE BULK OF THE ZONE AND TO FORM THE EMITTERBASE JUNCTION AT A DEPTH WHICH IS GREATER THAN OR EQUAL TO XT.
Claim 2
Independent Claim
266 words
A METHOD OF FABRICATING A TRANSISTORR COMPRISING THE STEPS OF: EXPOSING A SEMICONDUCTOR ZONE OF ONE CONDUCTIVITY TYPE TO A FIRST ION BEAM OF IMPURITIES OF OPPOSSITE CONDUCTIVITY TYPPE SO AS TO FORM A FIRST REGION OF IMPURITIES OF OPPOSITE CONDUCTIVITY TYPE THEREIN; EXPOSING SAID ZONE TO A SECOND ION BEAM OF IMPURITIES OF SAID OPPOSITE CONDUCTIVITY TYPE SO AS TO FORM A SECOND REGION OF IMPURITIES OF OPPOSITE CONDUCTIVITY TYPE THEREIN OVER THE AREA OF THE FIRST REGION WITH A PEAK DENSITY WHICH IS LESS THAN THE PEAK DENSITY OF THE FIRST REGION AND WHICH EXTENDS DEEPER INTO SAID ZONE THAN THE PEAK DENSITY OF THE FIRST REGION, SAID FIRST AND SECOND REGIONS OF IMPURITIES OVERLAPPING TO FORM A COMPOSITE REGION OF IMPURITIES COMPRISING THE BASE REGION WHICH IS DOMINATED BY THE IMPURITIES OF THE FIRST REGION FROM THE SURFACE OF THE BODY TO A DEPTH LESS THAN X1 AND WHICH IS DOMINATED BY THE IMPURITIES OF THE SECOND REGION AT A DEPTH GREATER THAN X1 AND FURTHER WHEREIN THERE EXISTS AT LEAST ONE POINT OF INFLECTION IN THE IMPURITY PROFILE OF THE COMPOSITE REGION; AND, FOLLOWING THE FORMATION OF SAID BASE REGION, FORMING AN EMITTER REGION OF IMPURITIES OF SAID ONE CONNDUCTIVITY TYPE WITHIN THE SEMICONDUCTOR ZONE WITHIN THE AREA DEFINED BY SAID BASE REGION BY EXPOSING SAID ZONE TO A THIRD ION BEAM OF IMPURITIES OF SAID ONE CONDUCTIVITY TYPE AND SUBSEQUENTLY HEATING SAID ZONE TO DIFFUSE THE IMPURITIES FURTHER INTO THE BULK OF THE ZONE AND TO FORM THE EMITTERBASE JUNCTION AT A DEPTH WHICH IS GREATER THAN OR EQUAL TO XT.
Claim 3
Dependent Claim
31 words
The method according to claim 1 wherein the first ion beam comprises boron ions at a dose of 1013 - 5 X 1014 ions/cm2 and energies in the range 20-50 keV.
Claim 4
Dependent Claim
31 words
The method according to claim 1 wherein the second ion beam comprises boron ions at a dose of 1012 - 2 X 1013 ions/cm2 and energies in the range 100-200 keV.
Claim 5
Dependent Claim
23 words
The method according to claim 1 wherein the third ion beam comprises impurities selected from the group consisting of As, p, and Sb.
Claim 6
Dependent Claim
29 words
The method according to claim 1 wherein the third ion beam comprises As ions at a dose of 1014 - 1017 ions/cm2 and energies in the range 5-300 keV.
Claim 7
Dependent Claim
30 words
The method according to claim 1 wherein the zone is heated to a temperature in the range 9001,300* C. for a time in the range 5 minutes to 3 hours.
References Cited (Backward Citations)
US3260624A
Cited
US3383567A
Cited
US3483443A
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US3595716A
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US3589949A
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US3729811A
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US3638300A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |