US4698127A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Process for fabricating a self-aligned bipolar transistor
Assignee: Fujitsu Ltd
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Filing: 1986-04-10
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Granted: 1987-10-06
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Expires: 2006-04-10
Abstract
Abstract Using a single mask pattern on a semiconductor substrate, a doped base contact region adjacent to the surface of the substrate, a buried insulating region below the base contact region, and an insulating layer on the base contact region, and optionally, a metal or metal silicide base-electrode-taking-out layer on the base contact region, are formed, respectively. Doped emitter and intrinsic base regions are formed below the mask pattern. A collector region is defined by the base contact region and the buried insulating layer to be inside thereof, i.e., below the mask pattern. Thus, a bipolar transistor is formed in a size that is essentially necessary, thereby reducing the collector-base capacitance, the base resistance, and the size of the device.
Inventors
- 👤 Osamu Hideshima
- 👤 Hiroshi Goto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 00:01
CPC Classifications
H; H10; H10D; H10D10/00; H10D10/01; H10D10/051; H10D64/00; H10D64/20; H10D64/27; H10D64/281; H10P; H10P76/00; H10P76/40; H10P76/408; H10P76/4085
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
188 words
A process for fabricating a bipolar transistor, comprising the steps of: preparing a semiconductor substrate; defining a first doped region of a first conductivity type adjacent to the surface of the semiconductor substrate; forming a mask layer on the first doped region, the mask layer having a pattern corresponding to that of an active area of the transistor to be formed; locally implanting ions into the first doped region, using the mask layer as a mask, to form a buried insulating layer; locally introducing dopants in the first doped region at the surface of the substrate and above the buried insulating layer, using the mask layer as a mask, to form a base contact region of a second conductivity type opposite to the first conductivity type; forming an intrinsic base region of the second conductivity type in the first doped region adjacent to the base contact region; forming an emitter region of the first conductivity type in the intrinsic base region and adjacent to the surface of the substrate; and using the first doped region of the first conductivity type below the intrinsic base region as a collector.
Claim 2
Dependent Claim
188 words
A process for fabricating a bipolar transistor, comprising the steps of: preparing a semiconductor substrate; defining a first doped region of a first conductivity type adjacent to the surface of the semiconductor substrate; forming a mask layer on the first doped region, the mask layer having a pattern corresponding to that of an active area of the transistor to be formed; locally implanting ions into the first doped region, using the mask layer as a mask, to form a buried insulating layer; locally introducing dopants in the first doped region at the surface of the substrate and above the buried insulating layer, using the mask layer as a mask, to form a base contact region of a second conductivity type opposite to the first conductivity type; forming an intrinsic base region of the second conductivity type in the first doped region adjacent to the base contact region; forming an emitter region of the first conductivity type in the intrinsic base region and adjacent to the surface of the substrate; and using the first doped region of the first conductivity type below the intrinsic base region as a collector.
Claim 3
Dependent Claim
26 words
A process according to claim 1, wherein the step of forming the buried insulating region is prior to the step of forming the base contact region.
Claim 4
Dependent Claim
26 words
A process according to claim 1, wherein the step of forming the base contact region is prior to the step of forming the buried insulating layer.
Claim 5
Dependent Claim
25 words
A process according to claim 1, wherein the step of forming the intrinsic base region is prior to the step of forming the emitter region.
Claim 6
Dependent Claim
25 words
A process according to claim 1, wherein the step of forming the emitter region is prior to the step of forming the intrinsic base region.
Claim 7
Dependent Claim
22 words
A process according to claim 1, further comprising the step of locally forming a second insulating layer above the base contact region.
Claim 8
Dependent Claim
30 words
A process according to claim 6, wherein the second insulating layer is formed by locally insulating the surface of the base contact region, using said mask layer as a mask.
Claim 9
Dependent Claim
47 words
A process according to claim 7, further comprising the step of opening a window in the second insulating layer to expose the surface of the base contact region in the window, followed by forming a base electrode in contact with the base contact layer through the window.
Claim 10
Dependent Claim
33 words
A process according to claim 6, further comprising the step of locally forming a metal or metal silicide layer on the base contact layer before the step of forming the second insulating layer.
Claim 11
Dependent Claim
48 words
A process according to claim 9, wherein the metal or metal silicide layer is formed by local deposition of a metal or metal silicide, onto the base contact region or by local deposition of a metal on the base contact region followed by silicidation of the deposited metal.
Claim 12
Dependent Claim
25 words
A process according to claim 9, wherein the second insulating layer is formed by making the surface of the metal or metal silicide layer insulating.
Claim 13
Dependent Claim
24 words
A process according to claim 11, wherein the second insulating layer is formed by anodizing the surface of the metal or metal silicide layer.
Claim 14
Dependent Claim
30 words
A process according to claim 9, wherein at least a part of the second insulating layer is formed by depositing an insulating material above the metal or metal silicide layer.
Claim 15
Dependent Claim
84 words
A process according to claim 13, wherein after depositing the insulating material above the metal or metal silicide layer and above the first doped region where at least a part of the mask layer is removed, anisotropic etching is conducted to remove the insulating material except the side wall portion of the metal or metal silicide layer, whereby an insulating wall having a desired lateral thickness of the insulating wall is formed at the side wall portion of the metal or metal silicide layer.
Claim 16
Dependent Claim
13 words
A process according to claim 1, wherein the semiconductor substrate is of silicon.
Claim 17
Dependent Claim
20 words
A process according to claim 1, wherein the buried insulating region is formed by implanting oxygen or nitrogen ions there.
Claim 18
Dependent Claim
22 words
A process according to claim 10, wherein the locally deposited metal or metal silicide is a refractory metal or a silicide thereof.
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) | 1990-10-05 | 1991-04-06 | 1991-10-06 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-10-05 | 1995-04-06 | 1995-10-06 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-10-05 | 1999-04-06 | 1999-10-06 | $7700.00 | Window Closed / Lapsed |