US4590664A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of fabricating low noise reference diodes and transistors
Assignee: Intersil Corp
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Filing: 1983-07-29
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Granted: 1986-05-27
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Expires: 2003-07-29
Abstract
Abstract The thick oxide over the surface portion of a P/N junction of a reference diode is removed, a thin oxide is grown thereon, and a contaminated shield layer is formed on the thin oxide. In addition to improving the reversed biased diode, the same method improves the forward biased emitter-base surface junction of a vertical bipolar transistor. The shield layer may be biased separate from the transistor.
Inventors
- 👤 John S. Prentice
- 👤 Gabriel J. Uscategui
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 11:13
CPC Classifications
H; H10; H10D; H10D64/00; H10D64/111; H10D10/00; H10D10/40; H10D10/421; H10D8/00; H10D8/20; H10D8/25; Y; Y10; Y10S; Y10S438/00; Y10S438/983
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
105 words
A method of fabricating a diode comprising: forming a P region and an N region in the surface of a substrate to be contiguous along a vertical diode junction extending down from said surface; oxidizing said surface to form a thick oxide; removing portions of said thick oxide to expose only said vertical junction and immediately adjacent arears of said P region and said N region at said surface and to remove contaminants; forming a thin oxide layer on said exposed surface; and forming a contaminant shield layer on said thin oxide over said vertical junction at said surface to protect said diode vertical junction.
Claim 2
Independent Claim
105 words
A method of fabricating a diode comprising: forming a P region and an N region in the surface of a substrate to be contiguous along a vertical diode junction extending down from said surface; oxidizing said surface to form a thick oxide; removing portions of said thick oxide to expose only said vertical junction and immediately adjacent arears of said P region and said N region at said surface and to remove contaminants; forming a thin oxide layer on said exposed surface; and forming a contaminant shield layer on said thin oxide over said vertical junction at said surface to protect said diode vertical junction.
Claim 3
Dependent Claim
23 words
The method according to claim 1 wherein said P and N regions are formed to be contiguous only along a substantially vertical plane.
Claim 4
Dependent Claim
32 words
The method according to claim 2 wherein said P and N regions are formed to have an impurity concentration which defines a breakdown voltage in the range of 5 to 7 volts.
Claim 5
Dependent Claim
16 words
The method according to claim 2 wherein said shield layer is formed of a conductive material.
Claim 6
Dependent Claim
24 words
The method according to claim 4 including forming conductive contacts to said P and N regions distinct from a contact to said shield layer.
Claim 7
Dependent Claim
26 words
The method according to claim 1 wherein said N region is formed first and said P region is formed in and encompassed by said N region.
Claim 8
Dependent Claim
16 words
The method according to claim 6 wherein said shield layer is formed of a conductive material.
Claim 9
Dependent Claim
20 words
The method according to claim 7 including forming conductive contacts to said P and N regions and said shield layer.
Claim 10
Dependent Claim
19 words
The method according to claim 8 including forming a conductive interconnect between said shield layer and P region contact.
Claim 11
Dependent Claim
32 words
The method according to claim 6 wherein said N and P regions are formed to have an impurity concentration which defines a breakdown voltage in the range of 5 to 7 volts.
Claim 12
Dependent Claim
26 words
The method according to claim 1 wherein said P region is formed first and said N region is formed in and encompassed by said P region.
Claim 13
Dependent Claim
16 words
The method according to claim 11 wherein said shield layer is formed of a conductive material.
Claim 14
Dependent Claim
20 words
The method according to claim 12 including forming conductive contacts to said P and N regions and said shield layer.
Claim 15
Dependent Claim
19 words
The method according to claim 13 including forming a conductive interconnect between said shield layer and N region contact.
Claim 16
Dependent Claim
23 words
The method according to claim 1 wherein said thin oxide is formed to a thickness in the range of 500 to 1500 angstroms.
Claim 17
Dependent Claim
18 words
The method according to claim 15 wherein said shield layer is formed of a doped polycrystalline semiconductor material.
Claim 18
Dependent Claim
14 words
The method according to claim 15 wherein said shield layer is formed of aluminum.
Claim 19
Independent Claim
153 words
A method of fabricating a buried diode comprising: forming a first region of a first conductivity type in a surface of a substrate of said first conductivity type and having a greater impurity concentration than said substrate; forming a second region of a second conductivity type opposite said first conductivity type over the surface of said first region and having a greater lateral area than said first region, the junction of said first and second regions being displaced from the surface of said substrate and form a vertical diode junction; oxidizing said surface to form a thick oxide; removing portions of said thick oxide to expose the vertical surface junction of said second region and said substrate and to remove contaminants; forming a thin oxide layer on said exposed surface; and forming a contaminant shield layer on said thin oxide over said vertical junction at said surface to protect said diode vertical junction.
Claim 20
Independent Claim
153 words
A method of fabricating a buried diode comprising: forming a first region of a first conductivity type in a surface of a substrate of said first conductivity type and having a greater impurity concentration than said substrate; forming a second region of a second conductivity type opposite said first conductivity type over the surface of said first region and having a greater lateral area than said first region, the junction of said first and second regions being displaced from the surface of said substrate and form a vertical diode junction; oxidizing said surface to form a thick oxide; removing portions of said thick oxide to expose the vertical surface junction of said second region and said substrate and to remove contaminants; forming a thin oxide layer on said exposed surface; and forming a contaminant shield layer on said thin oxide over said vertical junction at said surface to protect said diode vertical junction.
Claim 21
Dependent Claim
21 words
The method according to claim 18 wherein said shield layer is formed of a conductive material for forming a conductive layer.
Claim 22
Dependent Claim
26 words
The method according to claim 19 including forming a contact to said second region and an interconnect between said second region contact and said conductive layer.
Claim 23
Dependent Claim
36 words
The method according to claim 18 wherein said first and second regions are formed to have an impurity concentration which defines a breakdown voltage across said displaced junction in the range of 5 to 7 volts.
Claim 24
Dependent Claim
19 words
The method according to claim 18 wherein said thin oxide is formed to have a thickness under 2,000 angstroms.
Claim 25
Independent Claim
87 words
A method of fabricating a vertical bipolar transistor comprising: forming a base region in a surface in a collector region; forming an emitter region in the surface of said base region having a vertical junction; covering the surface with a thick oxide; removing portions of said thick oxide to expose a vertical portion of the emitter-base vertical junction at said surface; forming a thin oxide layer on said exposed surface; and forming a contaminant shield layer on said thin oxide over said vertical junction at said surface.
Claim 26
Independent Claim
87 words
A method of fabricating a vertical bipolar transistor comprising: forming a base region in a surface in a collector region; forming an emitter region in the surface of said base region having a vertical junction; covering the surface with a thick oxide; removing portions of said thick oxide to expose a vertical portion of the emitter-base vertical junction at said surface; forming a thin oxide layer on said exposed surface; and forming a contaminant shield layer on said thin oxide over said vertical junction at said surface.
Claim 27
Dependent Claim
39 words
A method according to claim 23 wherein said thin oxide and said shield layer are formed to have a thickness in combination less than the thickness of the thick oxide and to be encompassed laterally by said thick oxide.
Claim 28
Dependent Claim
31 words
A method according to claim 24 wherein said thin oxide and shield layer are formed to totally encompass said emitter regions and including forming an insulation layer over said shield layer.
Claim 29
Dependent Claim
64 words
A method according to claim 25 including removing portions of said thick oxide to expose portions of said emitter, base and collector regions and said insulation layer to expose portions of said shield layer, forming conductive contacts to said emitter, base and collector regions through said thick oxide and a conductive contact to said shield layer distinct from said emitter, base and collector contacts.
Claim 30
Dependent Claim
27 words
The method according to claim 26 wherein said shield layer is formed of a doped polycrystalline semiconductor material and said contact are formed of a metal material.
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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) | 1989-05-26 | 1989-11-25 | 1990-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1993-05-26 | 1993-11-25 | 1994-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1997-05-26 | 1997-11-25 | 1998-05-27 | $7700.00 | Window Closed / Lapsed |