US4497684A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Lift-off process for depositing metal on a substrate
Assignee: Fujitsu IT Holdings Inc
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Filing: 1983-02-22
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Granted: 1985-02-05
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Expires: 2003-02-22
Abstract
Abstract An improved method is set out for depositing a metal on a substrate to form a metal pattern. The method is particularly useful for the deposition of metal grids which form portions of microcircuits. The substrate is covered with a first sacrificial layer which is covered with a rigid second sacrificial layer which in turn is covered with a photoresist layer. The pattern which is to be deposited on the substrate is extended through the second sacrificial layer. Sufficient of the first sacrificial layer is removed to undercut the second sacrificial layer and to provide an overhanging lip portion of at least about 1000 Å overhang and an enlarged pattern on the substrate. Metal is deposited on the enlarged pattern and the first sacrificial layer is then eliminated while the metal pattern is left behind on the substrate.
Inventors
- 👤 Edward H. Sebesta
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 14:40
CPC Classifications
H; H10; H10P; H10P76/00; H10P76/40; H10P76/408; H10P76/4085; H10P76/20; H10P76/202; H05; H05K; H05K3/00; H05K3/10; H05K3/14; H05K3/143; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/944; Y10S438/948; Y10S438/951
Claims Analysis
Total Claims: 18
Claim 1
Independent Claim
203 words
A method of depositing a metal on a substrate to form a metal pattern, comprising: (a) providing a substrate having a surface covered with a first sacrificial layer of a greater thickness than said metal pattern, which first sacrificial layer is covered by a second rigid sacrificial layer, which is covered by a photoresist layer, which has one or more trenches exposing a pattern on the second sacrificial layer; (b) extending substantially the pattern through the second sacrificial layer to expose substantially the pattern on the first sacrificial layer without significantly affecting the photoresist layer or the first sacrificial layer; (c) selectively removing sufficient of the first sacrificial layer to partially undercut the second sacrificial layer to provide an overhanging lip portion and to expose an enlarged similar pattern on the substrate without significantly affecting the second sacrificial layer or the substrate, said lip portion overhanging said enlarged pattern by at least about 1000 Å; (d) stripping the photoresist layer from the second sacrificial layer without significiantly affecting the second sacrificial layer or the first sacrificial layer; (e) depositing the metal on the enlarged pattern on the substrate; and (f) eliminating the first sacrificial layer while leaving the metal pattern on the substrate.
Claim 2
Independent Claim
203 words
A method of depositing a metal on a substrate to form a metal pattern, comprising: (a) providing a substrate having a surface covered with a first sacrificial layer of a greater thickness than said metal pattern, which first sacrificial layer is covered by a second rigid sacrificial layer, which is covered by a photoresist layer, which has one or more trenches exposing a pattern on the second sacrificial layer; (b) extending substantially the pattern through the second sacrificial layer to expose substantially the pattern on the first sacrificial layer without significantly affecting the photoresist layer or the first sacrificial layer; (c) selectively removing sufficient of the first sacrificial layer to partially undercut the second sacrificial layer to provide an overhanging lip portion and to expose an enlarged similar pattern on the substrate without significantly affecting the second sacrificial layer or the substrate, said lip portion overhanging said enlarged pattern by at least about 1000 Å; (d) stripping the photoresist layer from the second sacrificial layer without significiantly affecting the second sacrificial layer or the first sacrificial layer; (e) depositing the metal on the enlarged pattern on the substrate; and (f) eliminating the first sacrificial layer while leaving the metal pattern on the substrate.
Claim 3
Dependent Claim
35 words
A method as set forth in claim 1, including, prior to said first sacrificial layer eliminating step (f), the additional step of: removing a sufficient portion of the metal to expose the first sacrificial layer.
Claim 4
Dependent Claim
27 words
A method as set forth in claim 1, wherein said second sacrificial layer is an inorganic dielectric layer and said extending step (b) comprises wet chemical etching.
Claim 5
Dependent Claim
17 words
A method as set forth in claim 3, wherein said selective removing step (c) comprises plasma etching.
Claim 6
Dependent Claim
45 words
A method as set forth in claim 4, including, prior to said first sacrificial layer eliminating step (f), the additional step of: removing a sufficient portion of the metal to expose the first sacrificial layer; and wherein: said metal removing step comprises wet chemical etching.
Claim 7
Dependent Claim
16 words
A method as set forth in claim 5, wherein said eliminating step (f) comprises plasma etching.
Claim 8
Dependent Claim
27 words
A method as set forth in claim 6, wherein said second sacrificial layer is an inorganic dielectric layer and said extending step (b) comprises wet chemical etching.
Claim 9
Dependent Claim
17 words
A method as set forth in claim 7, wherein said selective removing step (c) comprises plasma etching.
Claim 10
Dependent Claim
21 words
A method as set forth in claim 2, wherein said photoresist layer stripping step (d) precedes said selective removing step (c).
Claim 11
Dependent Claim
31 words
A method as set forth in claim 1, including, after said eliminating step (e), the additional step of: wet chemically etching away a portion of the metal in the metal pattern.
Claim 12
Dependent Claim
20 words
A method as set forth in claim 1, wherein said second sacrificial layer is 800 Å to 3000 Å thick.
Claim 13
Dependent Claim
39 words
A method as set forth in claim 2, wherein said second sacrificial layer is an inorganic dielectric layer and said extending step (b) comprises wet chemical etching with hydrogen fluoride or a solution of hydrogen fluoride and ammonium fluoride.
Claim 14
Dependent Claim
19 words
A method as set forth in claim 11, wherein said selective removing step (c) comprises plasma etching with oxygen.
Claim 15
Dependent Claim
20 words
A method as set forth in claim 13, wherein said metal removing step comprises wet chemical etching with an acid.
Claim 16
Dependent Claim
18 words
A method as set forth in claim 14, wherein said eliminating step (f) comprises plasma etching with oxygen.
Claim 17
Dependent Claim
31 words
A method as set forth in claim 15, including, after said eliminating step (f), the additional step of: wet chemically etching away a portion of the metal in the metal pattern.
Claim 18
Dependent Claim
17 words
A method as set forth in claim 16, wherein said first sacrificial layer comprises a polyimide polymer.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-02-05 | 1988-08-06 | 1989-02-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-02-05 | 1992-08-06 | 1993-02-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-02-05 | 1996-08-06 | 1997-02-05 | $7700.00 | Window Closed / Lapsed |