US4640738A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Semiconductor contact protection
Assignee: International Business Machines Corp
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Filing: 1984-06-22
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Granted: 1987-02-03
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Expires: 2004-06-22
Abstract
Abstract In a photoresist lift-off process for depositing metal on a semiconductor substrate, a protective coating of silicon is applied to an etched via hole prior to the metal deposition step. This prevents the formation of contaminant trapping voids and contaminated chemical residues which would otherwise occur at the base of the metal line subsequently deposited in the bottom of the via hole. The protective silicon layer, which has a thickness of from 100 to 300 angstroms, remains intact as a permanent part of the structure.
Inventors
- 👤 Edward C. Fredericks
- 👤 Madan M. Nanda
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-28 23:22
CPC Classifications
H; H10; H10W; H10W20/00; H10W20/40; H10W20/41; H10W20/44; H10W20/4451; H10P; H10P76/00; H10P76/20; H10P76/202; H10W20/01; H10W20/031; H10W20/056; Y; Y10; Y10S; Y10S438/00; Y10S438/942; Y10S438/948; Y10S438/951
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
147 words
In a metal lift-off process for the deposition of a metal structure on a substrate, a method for protecting the sides of the metal structure from attack by chemicals used in subsequent processing steps, comprising the steps of: providing a substrate with an overlying insulating layer; applying a layer of photoresist on the insulating layer; forming a window with sidewalls through the photoresist and insulating layers down to the substrate surface; flash evaporating a layer of protective semiconductor material which is resistant to attack by the chemicals used for photoresist removal on all surfaces of said sidewalls of said window; depositing contact metal in said window and in contact with the substrate surface and with the sides of the metal structure conforming to the surface of said protective layer covering the sidewalls of said window; and applying etching chemicals for photoresist removal and lift-off of undesired metal.
Claim 2
Dependent Claim
147 words
In a metal lift-off process for the deposition of a metal structure on a substrate, a method for protecting the sides of the metal structure from attack by chemicals used in subsequent processing steps, comprising the steps of: providing a substrate with an overlying insulating layer; applying a layer of photoresist on the insulating layer; forming a window with sidewalls through the photoresist and insulating layers down to the substrate surface; flash evaporating a layer of protective semiconductor material which is resistant to attack by the chemicals used for photoresist removal on all surfaces of said sidewalls of said window; depositing contact metal in said window and in contact with the substrate surface and with the sides of the metal structure conforming to the surface of said protective layer covering the sidewalls of said window; and applying etching chemicals for photoresist removal and lift-off of undesired metal.
Claim 3
Dependent Claim
14 words
The process as claimed in claim 1 wherein said protective semiconductor material is silicon.
Claim 4
Dependent Claim
14 words
The process as claimed in claim 1 wherein said protective semiconductor material is germanium.
Claim 5
Dependent Claim
23 words
The process as claimed in claim 1 wherein the thickness of the layer of protective semiconductor material is in the range 100-300 angstroms.
Claim 6
Dependent Claim
15 words
The process as claimed in claim 1 wherein said protective semiconductor material is gallium arsenide.
Claim 7
Dependent Claim
15 words
The process as claimed in claim 1 wherein said protective semiconductor material is indium phosphide.
Claim 8
Dependent Claim
57 words
The method of claim 1, wherein said substrate is selected from the group consisting of silicon and gallium arsenide; said metal is selected from the group consisting of aluminum, molybdenum, tungsten and titanium; and said photoresist is selected from the group consisting of optical photoresist, electron beam photoresist, positive photoresist and negative photoresist, wet or dry developable.
References Cited (Backward Citations)
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JPS5314570A
Cited
US4410622A
Cited
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Cited
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Cited
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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) | 1990-02-02 | 1990-08-04 | 1991-02-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-02-02 | 1994-08-04 | 1995-02-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-02-02 | 1998-08-04 | 1999-02-03 | $7700.00 | Window Closed / Lapsed |