US4256816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Mask structure for depositing patterned thin films
Assignee: AT&T Inc
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Filing: 1980-02-07
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Granted: 1981-03-17
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Expires: 2000-02-07
Abstract
Abstract A lift-off mask for the patterned deposition of thin films comprises a three layer sandwich of photoresist-aluminum-photoresist on a substrate. Deposition occurs through an opening in the top photoresist layer and through larger size (i.e., undercut) openings in the aluminum and bottom photoresist layers. The top layer of photoresist remains on the mask during deposition and defines the pattern, the bottom photoresist is fully exposed and in the openings provides an undercut which prevents edge tearing during lift-off, and the aluminum layer (typically 50-200 Angstroms thick) protects the bottom layer of photoresist from dissolving during formation of the top photoresist layer. Also described is a technique in which the edges of thin films are tapered by depositing them from a direction oblique to the substrate surface and by rotating the substrate during deposition. These techniques are specifically discussed in the context of fabricating Josephson junction devices.
Inventors
- 👤 La Rue N. Dunkleberger
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 14:23
CPC Classifications
G; G03; G03F; G03F7/00; G03F7/004; G03F7/09; G03F7/094; G03F7/26; H; H10; H10N; H10N60/00; H10N60/01; H10N60/0912; H10P; H10P76/00; H10P76/20; H10P76/202; H05; H05K; H05K3/00; H05K3/10; H05K3/14; H05K3/143
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
120 words
A structure for depositing patterned layers comprising: a substrate; a first layer of positive-acting photoresist material which has been completely exposed by optical radiation; a protective second layer approximately 50-200 Angstroms thick of metal material vacuum deposited on said first layer and effective to protect said first layer from dissolution during formation of a third layer; a third layer of positive-acting photoresist material formed on said protective second layer; and said first, second and third layers having substantially aligned apertures therein which expose a portion of said substrate, the aperture in said first layer being larger than that in said third layer and the aperture in said second layer being at least as large as that in said third layer.
Claim 2
Dependent Claim
120 words
A structure for depositing patterned layers comprising: a substrate; a first layer of positive-acting photoresist material which has been completely exposed by optical radiation; a protective second layer approximately 50-200 Angstroms thick of metal material vacuum deposited on said first layer and effective to protect said first layer from dissolution during formation of a third layer; a third layer of positive-acting photoresist material formed on said protective second layer; and said first, second and third layers having substantially aligned apertures therein which expose a portion of said substrate, the aperture in said first layer being larger than that in said third layer and the aperture in said second layer being at least as large as that in said third layer.
Claim 3
Dependent Claim
18 words
The structure of claim 1 wherein said second layer comprises a layer of aluminum approximately 50 Angstroms thick.
Claim 4
Dependent Claim
10 words
The structure of claim 1 wherein said substrate comprises silicon.
Claim 5
Dependent Claim
109 words
A structure for depositing patterned layers comprising: a silicon substrate; a first layer of positive-acting photoresist material which has been completely exposed to optical radiation; a second layer of aluminum vacuum deposited on said first layer to a thickness in the range of approximately 50-200 Angstroms; a third layer of positive-acting photoresist material formed on said second layer; and said first, second and third layers having substantially aligned apertures therein which expose a portion of said substrate, the aperture in said first layer being larger than that in said third layer, and the aperture in said second layer being at least as large as that in said third layer.
Claim 6
Dependent Claim
109 words
A structure for depositing patterned layers comprising: a silicon substrate; a first layer of positive-acting photoresist material which has been completely exposed to optical radiation; a second layer of aluminum vacuum deposited on said first layer to a thickness in the range of approximately 50-200 Angstroms; a third layer of positive-acting photoresist material formed on said second layer; and said first, second and third layers having substantially aligned apertures therein which expose a portion of said substrate, the aperture in said first layer being larger than that in said third layer, and the aperture in said second layer being at least as large as that in said third 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) | 1984-03-16 | 1984-09-15 | 1985-03-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1988-03-16 | 1988-09-15 | 1989-03-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1992-03-16 | 1992-09-15 | 1993-03-17 | $7700.00 | Window Closed / Lapsed |