Patent US6420097B1 successfully refreshed from Google Patents.
US6420097B1
Expired / Lapsed
US
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Hardmask trim process
Assignee: Ocean Semiconductor LLC
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Filing: 2000-05-02
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Granted: 2002-07-16
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Expires: 2020-05-02
Abstract
Abstract An improved method of forming circuit structures having linewidths which are smaller than what is achievable by conventional UV lithographic techniques on ultra-thin resist layers is provided. The method includes a hardmask which is patterned using an ultra-thin resist layer and is then trimmed to reduce the width of the hardmask before etching the underlying gate conductive layer.
Inventors
- 👤 Christopher L. Pike
- 👤 Scott A. Bell
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 15:45
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/71; H10D; H10D64/00; H10D64/01; H10D64/013; H10D64/01302; H10D64/01304; H10D64/01326
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
143 words
A method of forming circuit structures having linewidths which are smaller than what is achievable by conventional UV lithographic techniques on ultra-thin resist layers, said method comprising the steps of: providing a semiconductor wafer stack formed of a substrate and a device layer above the substrate; depositing a hardmask layer over the device layer; depositing an ultra-thin resist layer over the hardmask layer; forming a resist mask having an initial linewidth; anisotropically etching exposed portions of the hardmask layer; isotropically etching subsequently the hardmask layer underneath the resist mask to form a hardmask having a final linewidth which is narrower than the initial line width of the resist mask and corresponds to a desired structure linewidth; and anisotropically etching the device layer as defined by the hardmask to form a structure having a width substantially equal to the final linewidth of the hardmask.
Claim 2
Independent Claim
143 words
A method of forming circuit structures having linewidths which are smaller than what is achievable by conventional UV lithographic techniques on ultra-thin resist layers, said method comprising the steps of: providing a semiconductor wafer stack formed of a substrate and a device layer above the substrate; depositing a hardmask layer over the device layer; depositing an ultra-thin resist layer over the hardmask layer; forming a resist mask having an initial linewidth; anisotropically etching exposed portions of the hardmask layer; isotropically etching subsequently the hardmask layer underneath the resist mask to form a hardmask having a final linewidth which is narrower than the initial line width of the resist mask and corresponds to a desired structure linewidth; and anisotropically etching the device layer as defined by the hardmask to form a structure having a width substantially equal to the final linewidth of the hardmask.
Claim 3
Dependent Claim
20 words
A method of forming circuit structures as claimed in claim 1 , wherein the device layer is formed of silicon.
Claim 4
Dependent Claim
24 words
A method of forming circuit structures as claimed in claim 2 , wherein the silicon has a thickness between 500 Å to 5000 Å.
Claim 5
Dependent Claim
25 words
A method of forming circuit structures as claimed in claim 1 , wherein the ultra-thin resist layer has a thickness of less than 2500 Å.
Claim 6
Dependent Claim
21 words
A method of forming circuit structures as claimed in claim 4 , wherein the hardmask is made of an inorganic material.
Claim 7
Dependent Claim
28 words
A method of forming circuit structures as claimed in claim 5 , wherein the inorganic material is one of silicon dioxide, silicon nitride, silicon oxynitride, and titanium nitride.
Claim 8
Dependent Claim
22 words
A method of forming circuit structures as claimed in claim 4 , wherein the hardmask material is made of an organic material.
Claim 9
Dependent Claim
21 words
A method of forming circuit structures as claimed in claim 7 , wherein the organic material is a bottom anti-reflective coating.
Claim 10
Dependent Claim
25 words
A method of forming circuit structures as claimed in claim 4 , wherein the hardmask layer has a thickness between 50 Å to 500 Å.
Claim 11
Dependent Claim
41 words
A method of forming circuit structures as claimed in claim 1 , further comprising the step of exposing the resist layer to a UV bake prior to the step of isotropic over-etching so as to enhance selectivity to the hardmask layer.
Claim 12
Dependent Claim
41 words
A method of forming circuit structures as claimed in claim 1 , further comprising the step of curing the resist layer by an electron beam prior to the step of isotropic over-etching so as to enhance selectivity to the hardmask layer.
Claim 13
Dependent Claim
22 words
A method of forming circuit structures as claimed in claim 1 , wherein the hardmask layer is formed of a multi-layer material.
Claim 14
Dependent Claim
27 words
A method of forming circuit structures as claimed in claim 12 , wherein the multi-layer material consists of a top anti-reflective layer and a bottom etchstop layer.
Claim 15
Dependent Claim
23 words
A method of forming circuit structures as claimed in claim 13 , wherein the top anti-reflective layer is formed of a nitride film.
Claim 16
Dependent Claim
23 words
A method of forming circuit structures as claimed in claim 14 , wherein the bottom etchstop layer is formed of an oxide film.
Claim 17
Dependent Claim
34 words
A method of forming circuit structures as claimed in claim 1 , wherein the resist mask used in the isotropic etching step is removed prior to the anisotropic etching step of the device layer.
Claim 18
Dependent Claim
38 words
A method of forming circuit structures as claimed in claim 1 , wherein the resist mask used in the isotropic etching step is maintained on top of the hardmask during the anisotropic etching step of the device layer.
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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) | 2005-07-15 | 2006-01-14 | 2006-07-16 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2009-07-15 | 2010-01-14 | 2010-07-16 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2013-07-15 | 2014-01-14 | 2014-07-16 | $7700.00 | Window Closed / Lapsed |