US4892614A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Integrated circuit isolation process
Assignee: Texas Instruments Inc
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Filing: 1989-03-10
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Granted: 1990-01-09
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Expires: 2009-03-10
Abstract
Abstract A multiple recess isolation technology avoids stress induced defects while providing a substantially planar surface. A silicon substrate (10) is patterned and etched, creating active moat regions (18) and recesses (20a-b and 21a-b). the recesses are filled with oxide by growing a field oxide (40) in wide recessed regions (21) using a LOCOS process, while depositing a planarization field oxide (44) in narrow recessed regions (20). After etching the structure to obtain a planar surface, standard procedures are used to fabricate the active devices. The process uses a single photolithographic masking step and results in only a very small loss of the width electrically active regions.
Inventors
- 👤 Richard A. Chapman
- 👤 Clarence W. Teng
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 18:10
CPC Classifications
H; H10; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/014; H10W10/0143; H10W10/0145; H10W10/0147; H10W10/10; H10W10/17
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
218 words
A method of fabricating an isolation region at a surface of a semiconductor body, comprising: etching a recess having sides and a bottom into said surface of said semiconductor body, a portion of said surface not within said recess defined as an active region; forming an oxidation mask over said active region and along the sides and bottom of said recess; forming a masking layer over said oxidation mask, said masking layer having a portion near the center of said recess which is thinner than the portion of said masking layer near the sides of the recess; etching said masking layer so that the thinner portion of the masking layer is removed and so that portions of said masking layer remain within said recess near the sides of said recess; removing a portion of said oxidation mask at the bottom of said recess at the location not covered by the remaining portions of said masking layer near the sides of said recess; oxidizing a portion of said bottom of said recess at the location from which the portion of said oxidation mask was removed, to form a first oxide layer thereat; depositing a second oxide layer over said active region and into said recess after said oxidizing step; and etching said second oxide layer over said active region.
Claim 2
Independent Claim
218 words
A method of fabricating an isolation region at a surface of a semiconductor body, comprising: etching a recess having sides and a bottom into said surface of said semiconductor body, a portion of said surface not within said recess defined as an active region; forming an oxidation mask over said active region and along the sides and bottom of said recess; forming a masking layer over said oxidation mask, said masking layer having a portion near the center of said recess which is thinner than the portion of said masking layer near the sides of the recess; etching said masking layer so that the thinner portion of the masking layer is removed and so that portions of said masking layer remain within said recess near the sides of said recess; removing a portion of said oxidation mask at the bottom of said recess at the location not covered by the remaining portions of said masking layer near the sides of said recess; oxidizing a portion of said bottom of said recess at the location from which the portion of said oxidation mask was removed, to form a first oxide layer thereat; depositing a second oxide layer over said active region and into said recess after said oxidizing step; and etching said second oxide layer over said active region.
Claim 3
Dependent Claim
29 words
The method of claim 1, further comprising the step of removing said remaining portions of said masking layer near the sides of said recess prior to said oxidizing step.
Claim 4
Dependent Claim
12 words
The method of claim 1, wherein said oxidation mask comprises silicon nitride.
Claim 5
Dependent Claim
12 words
The method of claim 1, wherein said masking layer comprises silicon dioxide.
Claim 6
Dependent Claim
27 words
The method of claim 1, further comprising the step of: implanting channel stop dopant into the sides of said recess after said step of etching said recess.
Claim 7
Dependent Claim
50 words
The method of claim 1, wherein said step of etching said second oxide layer over said active region also etches said second oxide layer over said recess, so that the surface of said second oxide layer remaining in said recess is substantially coplanar with the surface of said active region.
Claim 8
Dependent Claim
75 words
The method of claim 1, further comprising: after said step of depositing said second oxide layer, depositing a conformal film over said second oxide layer; and wherein said step of etching said second oxide layer comprises etching said conformal film and said second oxide layer over said active region and said recess so that the surface of said second oxide layer remaining in said recess is substantially coplanar with the surface of said active region.
Claim 9
Independent Claim
274 words
A method of fabricating isolation regions at a surface of a semiconductor body, comprising: etching first and second recesses, each having sides and a bottom, into said surface of said semiconductor body, a portion of said surface not within said first or said second recess defined as an active region, and wherein the width of said first recess is greater than the width of said second recess; forming an oxidation mask over said active region and along the sides and bottom of said recesses; forming a masking layer over said oxidation mask, said masking layer having a portion near the center of said first recess which is thinner than the portion of said masking layer near the sides of the recess; etching said masking layer so that the thinner portion of the masking layer within said first recess is removed and so that portions of said masking layer remain within said first recess near the sides of said recess, and so that said masking layer remains across the width of said second recess; removing a portion of said oxidation mask at the bottom of said first recess at the location not covered by the remaining portions of said masking layer near the sides of said recess; removing the remaining portions of said masking layer; oxidizing a portion of said bottom of said first recess at the location from which the portion of said oxidation mask was removed, to form a first oxide layer thereat; depositing a second oxide layer over said active region and into said first and second recesses after said oxidizing step; and etching said second oxide layer over said active region.
Claim 10
Independent Claim
274 words
A method of fabricating isolation regions at a surface of a semiconductor body, comprising: etching first and second recesses, each having sides and a bottom, into said surface of said semiconductor body, a portion of said surface not within said first or said second recess defined as an active region, and wherein the width of said first recess is greater than the width of said second recess; forming an oxidation mask over said active region and along the sides and bottom of said recesses; forming a masking layer over said oxidation mask, said masking layer having a portion near the center of said first recess which is thinner than the portion of said masking layer near the sides of the recess; etching said masking layer so that the thinner portion of the masking layer within said first recess is removed and so that portions of said masking layer remain within said first recess near the sides of said recess, and so that said masking layer remains across the width of said second recess; removing a portion of said oxidation mask at the bottom of said first recess at the location not covered by the remaining portions of said masking layer near the sides of said recess; removing the remaining portions of said masking layer; oxidizing a portion of said bottom of said first recess at the location from which the portion of said oxidation mask was removed, to form a first oxide layer thereat; depositing a second oxide layer over said active region and into said first and second recesses after said oxidizing step; and etching said second oxide layer over said active region.
Claim 11
Dependent Claim
24 words
The method of claim 8, wherein the step of removing said remaining portions of said masking layer is performed prior to said oxidizing step.
Claim 12
Dependent Claim
12 words
The method of claim 8, wherein said oxidation mask comprises silicon nitride.
Claim 13
Dependent Claim
12 words
The method of claim 8, wherein said masking layer comprises silicon dioxide.
Claim 14
Dependent Claim
30 words
The method of claim 8, further comprising the step of: implanting channel stop dopant into the sides of said first and second recesses after said step of etching said recesses.
Claim 15
Dependent Claim
50 words
The method of claim 8, wherein said step of etching said second oxide layer over said active region also etches said second oxide layer over said recesses, so that the surface of said second oxide layer remaining in said recesses is substantially coplanar with the surface of said active region.
Claim 16
Dependent Claim
75 words
The method of claim 8, further comprising: after said step of depositing said second oxide layer, depositing a conformal film over said second oxide layer; and wherein said step of etching said second oxide layer comprises etching said conformal film and said second oxide layer over said active region and said recesses so that the surface of said second oxide layer remaining in said recesses is substantially coplanar with the surface of said active region.
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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) | 1993-01-08 | 1993-07-10 | 1994-01-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-01-08 | 1997-07-10 | 1998-01-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-01-08 | 2001-07-10 | 2002-01-09 | $7700.00 | Window Closed / Lapsed |