US5175603A
Expired / Lapsed
US
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Bipolar transistor
Assignee: Toshiba Corp
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Filing: 1991-12-10
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Granted: 1992-12-29
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Expires: 2011-12-10
Abstract
Abstract A bipolar transistor excellent in the high speed performance comprises a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration, a collector region of the first conductivity type formed on the buried region, a base region of a second conductivity type formed on the collector region, an emitter region of the first conductivity type formed on the base region, and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region. The concentration profile of the second conductivity type impurity in the depth direction of the outer base region is controlled in such a manner that, while the maximum voltage is applied between the base and emitter regions to turn the transistor on, the concentration of the second conductivity type impurity in the outer base region is kept higher than the concentration of the second conductivity type carrier in a base-widening region formed within the collector region, when the comparison is made at the same depth.
Inventors
- 👤 Toshihiko Hamasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 20:56
CPC Classifications
H; H10; H10D; H10D62/00; H10D62/10; H10D62/17; H10D62/177; H10D10/00; H10D10/40
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
230 words
A bipolar transistor, comprising: a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration; a collector region of the first conductivity type formed on the buried region; a base region of a second conductivity type formed on the collector region; an emitter region of the first conductivity type formed on the base region; and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region; wherein the concentration profile of the second conductivity type impurity in the depth direction of the outer base region is controlled in such a manner that, while the maximum voltage is applied between the base and emitter regions to turn the transistor on, the minimum concentration of the second conductivity type impurity in the outer base region is kept not lower than the maximum concentration of the second conductivity type carrier in a base-widening region formed within the collector region, when the comparison is made at the same depth, said concentration profile contributing to the charging of carriers in formed the base-widening region and to the discharging of carriers when the base-widening region vanishes.
Claim 2
Dependent Claim
230 words
A bipolar transistor, comprising: a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration; a collector region of the first conductivity type formed on the buried region; a base region of a second conductivity type formed on the collector region; an emitter region of the first conductivity type formed on the base region; and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region; wherein the concentration profile of the second conductivity type impurity in the depth direction of the outer base region is controlled in such a manner that, while the maximum voltage is applied between the base and emitter regions to turn the transistor on, the minimum concentration of the second conductivity type impurity in the outer base region is kept not lower than the maximum concentration of the second conductivity type carrier in a base-widening region formed within the collector region, when the comparison is made at the same depth, said concentration profile contributing to the charging of carriers in formed the base-widening region and to the discharging of carriers when the base-widening region vanishes.
Claim 3
Dependent Claim
30 words
The bipolar transistor according to claim 1, wherein the junction between the base region and the emitter region is flat as a whole and does not include a curved portion.
Claim 4
Dependent Claim
29 words
The bipolar transistor according to claim 2, wherein an insulation film is formed to surround the side end of the junction between the base region and the emitter region.
Claim 5
Dependent Claim
27 words
The bipolar transistor according to claim 1, wherein an insulation film is formed below the outer base region to surround the side end of the collector region.
Claim 6
Dependent Claim
337 words
A bipolar transistor, comprising: a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration; a collector region of the first conductivity type formed on the buried region; a base region of a second conductivity type formed on the collector region; an emitter region of the first conductivity type formed on the base region; and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region; wherein the concentration profile of the second conductivity type impurity in the depth direction of the outer base region is controlled in such a manner that, while the maximum voltage is applied between the base and emitter regions to turn the transistor on, the minimum concentration of the second conductivity type impurity in the outer base region is kept not lower than the maximum concentration of the second conductivity type carrier in a base-widening region formed within the collector region, when the comparison is made at the same depth; the PN junction formed between the base region and the emitter region is flat as a whole and does not include a curved portion; the PN junction formed between the base region and the collector region is parallel with the PN junction between the base and emitter regions, and the both ends of the PN junction between the base and collector regions are positioned inside the both ends of the PN junction between the base and emitter regions; and the PN junction formed between the collector region and the outer base region is inclined to flare from the flat PN junction between the base and collector regions, said concentration profile contributing to the charging of carriers in forming the base-widening region and to the discharging of carriers when the base-widening region vanishes.
Claim 7
Dependent Claim
337 words
A bipolar transistor, comprising: a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration; a collector region of the first conductivity type formed on the buried region; a base region of a second conductivity type formed on the collector region; an emitter region of the first conductivity type formed on the base region; and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region; wherein the concentration profile of the second conductivity type impurity in the depth direction of the outer base region is controlled in such a manner that, while the maximum voltage is applied between the base and emitter regions to turn the transistor on, the minimum concentration of the second conductivity type impurity in the outer base region is kept not lower than the maximum concentration of the second conductivity type carrier in a base-widening region formed within the collector region, when the comparison is made at the same depth; the PN junction formed between the base region and the emitter region is flat as a whole and does not include a curved portion; the PN junction formed between the base region and the collector region is parallel with the PN junction between the base and emitter regions, and the both ends of the PN junction between the base and collector regions are positioned inside the both ends of the PN junction between the base and emitter regions; and the PN junction formed between the collector region and the outer base region is inclined to flare from the flat PN junction between the base and collector regions, said concentration profile contributing to the charging of carriers in forming the base-widening region and to the discharging of carriers when the base-widening region vanishes.
Claim 8
Dependent Claim
29 words
The bipolar transistor according to claim 5, wherein an insulation film is formed to surround the side end of the junction between the base region and the -emitter region.
Claim 9
Dependent Claim
27 words
The bipolar transistor according to claim 5, wherein an insulation film is formed below the outer base region to surround the side end of the collector region.
Claim 10
Dependent Claim
196 words
A bipolar transistor, comprising: a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration; a collector region of the first conductivity type formed on the buried region; a base region of a second conductivity type formed on the collector region; an emitter region of the first conductivity type formed on the base region; and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region; wherein the PN junction formed between the base region and the emitter region is flat as a whole and does not include a curved portion; and the PN junction formed between the base region and the collector region is parallel with the PN junction between the base and emitter regions, and the both ends of the PN junction between the base and collector regions are positioned inside the both ends of the PN junction between the base and emitter regions.
Claim 11
Dependent Claim
196 words
A bipolar transistor, comprising: a buried region of a first conductivity type formed in a semiconductor substrate, said buried region having a high impurity concentration; a collector region of the first conductivity type formed on the buried region; a base region of a second conductivity type formed on the collector region; an emitter region of the first conductivity type formed on the base region; and an outer base region of the second conductivity type formed to surround the base and collector regions in such a manner that an ohmic contact is provided between the base region and said outer base region and a p-n junction is formed between the collector region and said outer base region; wherein the PN junction formed between the base region and the emitter region is flat as a whole and does not include a curved portion; and the PN junction formed between the base region and the collector region is parallel with the PN junction between the base and emitter regions, and the both ends of the PN junction between the base and collector regions are positioned inside the both ends of the PN junction between the base and emitter regions.
Claim 12
Dependent Claim
36 words
The bipolar transistor according to claim 8, wherein the PN junction formed between the collector region and the outer base region is inclined to flare from the flat PN junction between the base and collector regions.
Claim 13
Dependent Claim
29 words
The bipolar transistor according to claim 8, wherein an insulation film is formed to surround the side end of the junction between the base region and the emitter region.
Claim 14
Dependent Claim
27 words
The bipolar transistor according to claim 8, wherein an insulation film is formed below the outer base region to surround the side end of the collector region.
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) | 1995-12-29 | 1996-06-29 | 1996-12-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-12-29 | 2000-06-29 | 2000-12-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-12-29 | 2004-06-29 | 2004-12-29 | $7700.00 | Window Closed / Lapsed |