Patent US5914280A successfully refreshed from Google Patents.
US5914280A
Expired / Lapsed
US
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Deep trench etch on bonded silicon wafer
Assignee: Intersil Americas LLC
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Filing: 1996-12-23
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Granted: 1999-06-22
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Expires: 2016-12-23
Abstract
Abstract A quick, deep, clean two step trench process for an SOI/bonded wafer substrate 100 is disclosed. A first isotropic plasma etch using SF6 is made through an opening 40 in the photoresist layer on device layer 16. A second anisotropic plasma etch using SF6 and Cl2 stops on the isolation/bond oxide layer 14. The bottom of the trench 60 is overetched to form cavities 50 on the isolation/bond oxide layer 14 without removing a substantial portion of that layer.
Inventors
- 👤 Peter Victor Gelzinis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:08
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/60; H10P50/64; H10P50/642; H10P50/20; H10P50/24; H10P50/242; H10P50/69; H10P50/691; H10P90/00; H10P90/19; H10P90/1904; H10P90/1906; H10W; H10W10/00; H10W10/01; H10W10/011; H10W10/014; H10W10/0145; H10W10/041; H10W10/061; H10W10/10; H10W10/17; H10W10/181; H10W10/40; H10P76/00; H10P76/20; H10P76/204; H10P76/2041; H10P90/1914
Claims Analysis
Total Claims: 21
Claim 1
Independent Claim
75 words
A method for forming an isolation trench around an island of silicon in a silicon device layer disposed on an insulator layer in a silicon-on-insulator substrate comprising the steps of: covering the device layer with non-oxide masking layer; forming a trench pattern in the non-oxide masking layer; isotropically etching an upper portion of the trench; and after said isotropic etch, anisotropically etching the lower portion of the trench to the level of the insulator layer.
Claim 2
Independent Claim
75 words
A method for forming an isolation trench around an island of silicon in a silicon device layer disposed on an insulator layer in a silicon-on-insulator substrate comprising the steps of: covering the device layer with non-oxide masking layer; forming a trench pattern in the non-oxide masking layer; isotropically etching an upper portion of the trench; and after said isotropic etch, anisotropically etching the lower portion of the trench to the level of the insulator layer.
Claim 3
Dependent Claim
22 words
The method of claim 1 wherein the step of isotropically etching the upper portion of the trench comprises plasma etching with SF6.
Claim 4
Dependent Claim
24 words
The method of claim 1 wherein the step of anisotropically etching the lower portion of the trench comprises plasma etching with SF6 and Cl2.
Claim 5
Dependent Claim
12 words
The method of claim 1 wherein the non-oxide masking layer is photoresist.
Claim 6
Dependent Claim
25 words
The method of claim 4 wherein the step of covering the device layer with photoresist comprises depositing a layer of photoresist on the device layer.
Claim 7
Dependent Claim
18 words
The method of claim 1 comprising a further step of overetching silicon at the bottom of the trench.
Claim 8
Dependent Claim
56 words
The method of claim 1 wherein the step of anisotropically etching the lower portion of the trench exposes a portion of an insulator layer at the bottom of the trench and comprising a further step of removing the non-oxide masking layer without removing a significant amount of the insulator layer at the bottom of the trench.
Claim 9
Dependent Claim
25 words
The method of claim 1 wherein about 10-30 percent of the trench is isotropically etched and about 90-70 percent of the trench is anisotropically etched.
Claim 10
Dependent Claim
30 words
The method of claim 1 wherein the maximum width of the upper portion of the trench is about twice the width of the anisotropically etched lower portion of the trench.
Claim 11
Independent Claim
115 words
A method for forming an isolation trench around an island of silicon in a silicon device layer on an insulator layer in a silicon-on-insulator substrate comprising the steps of: covering the device layer with a layer of photoresist; forming a trench pattern in the layer of photoresist; etching a trench mouth into the device layer, said trench mouth having a tapered sidewall with a first slope with respect to an axis perpendicular to the device layer; and after etching the trench mouth, etching a trench body to the level of the insulator layer, said trench body having a second slope with respect to said axis, wherein the first slope is greater than the second slope.
Claim 12
Independent Claim
115 words
A method for forming an isolation trench around an island of silicon in a silicon device layer on an insulator layer in a silicon-on-insulator substrate comprising the steps of: covering the device layer with a layer of photoresist; forming a trench pattern in the layer of photoresist; etching a trench mouth into the device layer, said trench mouth having a tapered sidewall with a first slope with respect to an axis perpendicular to the device layer; and after etching the trench mouth, etching a trench body to the level of the insulator layer, said trench body having a second slope with respect to said axis, wherein the first slope is greater than the second slope.
Claim 13
Dependent Claim
18 words
The method of claim 10 wherein the step of etching the trench mouth comprises plasma etching with SF6.
Claim 14
Dependent Claim
20 words
The method of claim 10 wherein the step of etching the trench body comprises plasma etching with SF6 and CL2.
Claim 15
Dependent Claim
25 words
The method of claim 10 wherein the step of covering the device layer with photoresist comprises depositing a layer of photoresist on the device layer.
Claim 16
Dependent Claim
18 words
The method of claim 10 comprising a further step of overetching silicon at the bottom of the trench.
Claim 17
Dependent Claim
56 words
The method of claim 10 wherein the step of anisotropically etching the lower portion of the trench exposes a portion of an insulator layer at the bottom of the trench and comprising a further step of removing the non-oxide masking layer without removing a significant amount of the insulator layer at the bottom of the trench.
Claim 18
Independent Claim
130 words
A method for forming an isolation trench around an island of silicon in a silicon device layer on a insulator layer in a silicon-on-insulator substrate comprising the steps of: depositing a layer of photoresist on the device layer; patterning the photoresist layer to form a trench pattern therein and exposing a portion of the device layer to define a mouth of a trench; etching a trench mouth into the device layer, said trench mouth having a tapered sidewall with a first slope with respect to an axis perpendicular to the device layer; and after etching the trench mouth, etching a trench body to the level of the insulator, said trench body having a second slope with respect to said axis, wherein the first slope is greater than the second slope.
Claim 19
Independent Claim
130 words
A method for forming an isolation trench around an island of silicon in a silicon device layer on a insulator layer in a silicon-on-insulator substrate comprising the steps of: depositing a layer of photoresist on the device layer; patterning the photoresist layer to form a trench pattern therein and exposing a portion of the device layer to define a mouth of a trench; etching a trench mouth into the device layer, said trench mouth having a tapered sidewall with a first slope with respect to an axis perpendicular to the device layer; and after etching the trench mouth, etching a trench body to the level of the insulator, said trench body having a second slope with respect to said axis, wherein the first slope is greater than the second slope.
Claim 20
Dependent Claim
14 words
The method of claim 16 wherein the etching steps comprise plasma etching with SF6.
Claim 21
Dependent Claim
18 words
The method of claim 16 comprising a further step of overetching silicon at the bottom of the 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) | 2002-06-21 | 2002-12-21 | 2003-06-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2006-06-21 | 2006-12-21 | 2007-06-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2010-06-21 | 2010-12-21 | 2011-06-22 | $7700.00 | Window Closed / Lapsed |