US5468676A
Expired / Lapsed
US
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Trench isolation structure and method for forming
Assignee: Texas Instruments Inc
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Filing: 1994-06-17
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Granted: 1995-11-21
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Expires: 2014-06-17
Abstract
Abstract An isolation structure is disclosed which isolates an active region (24) from other proximate active regions. The isolation structure utilizes the combination of a LOCOS structure (26) comprising bird's beak structure (26a) and (26b). A trench (34) is formed through the LOCOS structure (26). A channel stop implant region (40) is formed along the sidewalls of the trench (34). A trench plug (46) is used to fill the trench. The isolation structure thereby uses the isolation capabilities of trench isolation structures, but prevents the leakage currents common along trench sidewalls by isolating the trench sidewalls from the active region using the LOCOS structures.
Inventors
- 👤 Sudhir K. Madan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 13:34
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/012; H10P; H10P50/00; H10P50/69; H10P50/691; H10P50/693; H10P50/695; H10W10/014; H10W10/0145; H10W10/0147; H10W10/041; H10W10/10; H10W10/13; H10W10/17; H10W10/40; Y; Y10; Y10S; Y10S148/00; Y10S148/05
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
147 words
A method of forming an isolation structure in a semiconductor layer between first and second active regions in order to electrically isolate the first and second active regions one from the other, the semiconductor layer comprising an outer surface, the method comprising the steps of: forming a LOCOS structure on the outer surface, the LOCOS structure formed to comprise a first bird's beak structure disposed adjacent the first active region and a second bird's beak structure disposed adjacent the second active region; forming a first and second trench through the LOCOS structure between the first and second bird's beak structures and the semiconductor layer; and forming a first trench plug in the first trench and a second trench plug in the second trench, the first and second trenches each comprising sidewalls defining an interface between each of the first and second trench plugs and the semiconductor layer.
Claim 2
Independent Claim
147 words
A method of forming an isolation structure in a semiconductor layer between first and second active regions in order to electrically isolate the first and second active regions one from the other, the semiconductor layer comprising an outer surface, the method comprising the steps of: forming a LOCOS structure on the outer surface, the LOCOS structure formed to comprise a first bird's beak structure disposed adjacent the first active region and a second bird's beak structure disposed adjacent the second active region; forming a first and second trench through the LOCOS structure between the first and second bird's beak structures and the semiconductor layer; and forming a first trench plug in the first trench and a second trench plug in the second trench, the first and second trenches each comprising sidewalls defining an interface between each of the first and second trench plugs and the semiconductor layer.
Claim 3
Dependent Claim
29 words
The method of claim 1 and further comprising the step of forming a channel stop region in the semiconductor layer adjacent the sidewalls of the first and second trenches.
Claim 4
Dependent Claim
28 words
The method of claim 2 wherein said step of forming a channel stop region comprises the step of diffusing impurities into the semiconductor layer using solid source materials.
Claim 5
Dependent Claim
34 words
The method of claim 1, wherein the semiconductor layer comprises a conductivity type and wherein said step of forming a channel stop region comprises the step of implanting impurities corresponding to the conductivity type.
Claim 6
Dependent Claim
46 words
The method of claim 1 wherein said step of forming a first and a second trench plug comprises the step of forming a region of polycrystalline semiconductor material and a region comprising an oxide of said semiconductor material in both said first and said second trenches.
Claim 7
Dependent Claim
39 words
The method of claim 1, wherein said step of forming a first and second trench plug comprises the step of forming a region comprising oxide and a region comprising phosphosilicon glass in both said first and said second trench.
Claim 8
Dependent Claim
39 words
The method of claim 1 wherein said step of forming a first and second trench plug comprises the step of forming a region comprising oxide and a region comprising borophosphosilicon glass in both said first and said second trench.
Claim 9
Independent Claim
198 words
A method of forming an isolation structure in a semiconductor layer between first and second active regions in order to electrically isolate the first and second active regions one from the other, the semiconductor layer comprising an outer surface, the method comprising the steps of: forming a pad oxide layer on the outer surface; forming a nitride layer outwardly from the pad oxide layer; forming a thick oxide layer outwardly from the nitride layer; etching an opening through the thick oxide layer and the nitride layer to expose a portion of the pad oxide layer; forming a LOCOS structure using the exposed portion of the pad oxide layer, the LOCOS structure formed to comprise a first bird's beak structure disposed adjacent the first active region and a second bird's beak structure disposed adjacent the second active region; etching a trench through the LOCOS structure and into the semiconductor layer, the trench formed, in part, between the first and second bird's beak structures; forming a channel stop region by introducing impurities into the semiconductor layer adjacent sidewalls of the trench; forming a trench plug in the trench; and removing the remaining portions of the thick oxide and nitride layers.
Claim 10
Independent Claim
198 words
A method of forming an isolation structure in a semiconductor layer between first and second active regions in order to electrically isolate the first and second active regions one from the other, the semiconductor layer comprising an outer surface, the method comprising the steps of: forming a pad oxide layer on the outer surface; forming a nitride layer outwardly from the pad oxide layer; forming a thick oxide layer outwardly from the nitride layer; etching an opening through the thick oxide layer and the nitride layer to expose a portion of the pad oxide layer; forming a LOCOS structure using the exposed portion of the pad oxide layer, the LOCOS structure formed to comprise a first bird's beak structure disposed adjacent the first active region and a second bird's beak structure disposed adjacent the second active region; etching a trench through the LOCOS structure and into the semiconductor layer, the trench formed, in part, between the first and second bird's beak structures; forming a channel stop region by introducing impurities into the semiconductor layer adjacent sidewalls of the trench; forming a trench plug in the trench; and removing the remaining portions of the thick oxide and nitride layers.
Claim 11
Dependent Claim
24 words
The method of claim 8 wherein said step of forming a channel stop region comprises the step of implanting impurities into the semiconductor layer.
Claim 12
Dependent Claim
27 words
The method of claim 8 wherein said step of forming a channel stop region comprises the step-of diffusing impurities into the semiconductor layer using solid source materials.
Claim 13
Dependent Claim
41 words
The method of claim 8 and further comprising the step of forming, prior to said step of etching a trench, spacer structures outwardly from the LOCOS structure and adjacent the remaining portions of the nitride layer and the thick oxide layer.
Claim 14
Dependent Claim
34 words
The method of claim 8 wherein said step of forming a trench plug comprises the step of forming a region of polycrystalline semiconductor material and a region comprising an oxide of said semiconductor material.
Claim 15
Dependent Claim
28 words
The method of claim 8 wherein said step of forming a trench plug comprises the step of forming a region comprising oxide and a region comprising phosphosilicon glass.
Claim 16
Dependent Claim
28 words
The method of claim 8 wherein said step of forming a trench plug comprises the step of forming a region comprising oxide and a region comprising borophosphosilicon glass.
Claim 17
Dependent Claim
68 words
The method of claim 8 wherein said step of forming a trench plug comprises the step of foxing a first trench plug in a first trench and further comprising the steps of forming a second trench through said LOCOS structure proximate the first trench between the first and second bird's beak structures and in the semiconductor layer and foxing a second trench plug disposed in the second trench.
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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) | 1998-11-20 | 1999-05-22 | 1999-11-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-11-20 | 2003-05-22 | 2003-11-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-11-20 | 2007-05-22 | 2007-11-21 | $7700.00 | Window Closed / Lapsed |