US5618751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of making single-step trenches using resist fill and recess
Assignee: International Business Machines Corp
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Filing: 1996-05-23
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Granted: 1997-04-08
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Expires: 2016-05-23
Abstract
Abstract A trench capacitor with a buried plate is formed with a single etching process by the expedient of filling the trench so formed and lined with diffusion source material with resist by baking and reflowing the resist which also serves to adjust exposure sensitivity of the resist such that exposure and development of the resist removes the resist to a repeatable and uniform depth. Remaining resist allows etching of the diffusion source layer to a very accurate dimension. Thus only a readily formed oxide or TECS layer is needed to confine impurities during diffusion to form the buried plate. An isolation collar can be formed after recess of the fill to avoid formation of step corners and erosion of the isolation collar by repeated fill and etch back processes while permitting maximum capacitance to be achieved for a given trench "footprint".
Inventors
- 👤 Kevin M. Golden
- 👤 Pai-Hung Pan
- 👤 Kevin J. Stewart
- 👤 Alan C. Thomas
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 01:10
CPC Classifications
H; H10; H10B; H10B12/00; H10B12/01; H10B12/02; H10B12/03; H10B12/038; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/948; Y10S438/949
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
65 words
A method of fabrication of a trench capacitor including the steps of forming a trench in a substrate, forming a diffusion source layer within said trench, filling said trench with a resist, exposing and developing said resist to a depth less than a depth of said trench, etching said diffusion source in accordance with an unexposed portion of said resist, and completing said trench capacitor.
Claim 2
Independent Claim
65 words
A method of fabrication of a trench capacitor including the steps of forming a trench in a substrate, forming a diffusion source layer within said trench, filling said trench with a resist, exposing and developing said resist to a depth less than a depth of said trench, etching said diffusion source in accordance with an unexposed portion of said resist, and completing said trench capacitor.
Claim 3
Dependent Claim
31 words
A method as recited in claim 1, including the further step of applying a layer of material over said diffusion source layer for enhancing adhesion of said resist within said trench.
Claim 4
Dependent Claim
24 words
A method as recited in claim 1, wherein said step of filling said trench with resist includes the further step of reflowing said resist.
Claim 5
Dependent Claim
18 words
A method as recited in claim 1, including the further step of adjusting exposure sensitivity of said resist.
Claim 6
Dependent Claim
21 words
A method as recited in claim 4, wherein said step of adjusting exposure sensitivity includes a step of baking said resist.
Claim 7
Dependent Claim
24 words
A method as recited in claim 1, wherein said step of forming said trench within said substrate is performed by a single etching operation.
Claim 8
Dependent Claim
44 words
A method as recited in claim 1, wherein said step of forming said trench is performed by lithography at a first wavelength and said step of exposing said resist is performed at a second wavelength, said second wavelength being shorter than said first wavelength.
Claim 9
Dependent Claim
44 words
A method as recited in claim 4, wherein said step of forming said trench is performed by lithography at a first wavelength and said step of exposing said resist is performed at a second wavelength, said second wavelength being shorter than said first wavelength.
Claim 10
Dependent Claim
34 words
A method as recited in claim 3, including the further step of baking said resist and wherein a process step for baking said resist is combined with a process step for reflowing said resist.
Claim 11
Dependent Claim
26 words
A method as recited in claim 9 wherein said step of baking said resist and reflowing said resist serve to adjust exposure sensitivity of said resist.
Claim 12
Dependent Claim
20 words
A method as recited in claim 7, wherein said step of exposing said resist is performed with an electron beam.
Claim 13
Dependent Claim
36 words
A method as recited in claim 11, including the further step of controlling an accelerating voltage of said electron beam such that said resist is exposed to a depth less than the depth of said trench.
Claim 14
Independent Claim
76 words
A method of fabrication of a trench structure with a buried connection adjacent thereto including the steps of forming a trench in a substrate, forming a diffusion source layer within said trench, filling said trench with a resist, exposing and developing said resist to a depth less than a depth of said trench, etching said diffusion source in accordance with an unexposed portion of said resist, and diffusing impurities from said diffusion source into said substrate.
Claim 15
Independent Claim
76 words
A method of fabrication of a trench structure with a buried connection adjacent thereto including the steps of forming a trench in a substrate, forming a diffusion source layer within said trench, filling said trench with a resist, exposing and developing said resist to a depth less than a depth of said trench, etching said diffusion source in accordance with an unexposed portion of said resist, and diffusing impurities from said diffusion source into said substrate.
Claim 16
Dependent Claim
31 words
A method as recited in claim 13, including the further step of applying a layer of material over said diffusion source layer for enhancing adhesion of said resist within said trench.
Claim 17
Dependent Claim
24 words
A method as recited in claim 13, wherein said step of filling said trench with resist includes the further step of reflowing said resist.
Claim 18
Dependent Claim
18 words
A method as recited in claim 13, including the further step of adjusting exposure sensitivity of said resist.
Claim 19
Dependent Claim
44 words
A method as recited in claim 13 wherein said step of forming said trench is performed by lithography at a first wavelength and said step of exposing said resist is performed at a second wavelength, said second wavelength being shorter than said first wavelength.
Claim 20
Dependent Claim
34 words
A method as recited in claim 15, including the further step of baking said resist and wherein a process step for baking said resist is combined with a process step for reflowing said resist.
Claim 21
Dependent Claim
31 words
A method as recited in claim 18 wherein one of a step of baking said resist and a step of reflowing said resist serve to adjust exposure sensitivity of said resist.
Claim 22
Dependent Claim
51 words
A method as recited in claim 13, wherein said step of exposing said resist includes the further step of exposing said resist with an electron beam and controlling an accelerating voltage of said electron beam such that said resist is exposed to a depth less than the depth of said 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) | 2000-04-07 | 2000-10-07 | 2001-04-08 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2004-04-07 | 2004-10-07 | 2005-04-08 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2008-04-07 | 2008-10-07 | 2009-04-08 | $7700.00 | Window Closed / Lapsed |