US4489146A
Expired / Lapsed
US
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Reverse process for making chromium masks using silicon dioxide dry etch mask
Assignee: International Business Machines Corp
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Filing: 1983-08-17
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Granted: 1984-12-18
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Expires: 2003-08-17
Abstract
Abstract On a substrate (1) covered with a chromium layer (2), a positive resist layer (3) is applied, exposed through an exposure mask with the mask pattern corresponding to the negative of the respective chromium pattern, developed, and blanket-coated with a less than or equal to 10 nm thick layer (4) of silicon dioxide. Then photoresist layer (3) and the silicon layer (4) thereon are lifted off, and finally the chromium layer (2) is dry-etched, the remaining silicon dioxide layer (4) being used as an etch mask. Chromium masks are used e.g. in the production of semiconductor circuits. By means of the reverse process, structures whose smallest dimensions are in the micrometer and the submicrometer range can be transferred into chromium layers with sharp edges.
Inventors
- 👤 Gunther Bock
- 👤 Bernhard Hafner
- 👤 Reinhold Muhl
- 👤 Klaus P. Thiel
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 20:40
CPC Classifications
G; G03; G03F; G03F1/00; G03F1/68; G03F1/80
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
153 words
A reverse process for making a chromium mask comprising: providing a substrate coated with a chromium layer; applying a layer of positive resist onto the chromium layer; exposing the said resist through an exposure mask, developing the resist and removing the unwanted portions thereof; blanket coating by cathode sputtering a layer of a silicon dioxide material which is dry-etched more slowly than said chromium layer; said conditions of said cathode sputtering is such that a layer of chromium oxide in the order of nanometers in thickness forms between said chromium layer and said silicon dioxide layer resulting in superior adherence between the said chromium and silicon dioxide layers; lifting off said blanket-coating layer where it is upon said resist and leaving the said blanket-coating where it is upon said chromium layer; and dry etching said chromium layer while using the remaining said blanket-coating layer as an etch mask to form said chromium mask.
Claim 2
Dependent Claim
153 words
A reverse process for making a chromium mask comprising: providing a substrate coated with a chromium layer; applying a layer of positive resist onto the chromium layer; exposing the said resist through an exposure mask, developing the resist and removing the unwanted portions thereof; blanket coating by cathode sputtering a layer of a silicon dioxide material which is dry-etched more slowly than said chromium layer; said conditions of said cathode sputtering is such that a layer of chromium oxide in the order of nanometers in thickness forms between said chromium layer and said silicon dioxide layer resulting in superior adherence between the said chromium and silicon dioxide layers; lifting off said blanket-coating layer where it is upon said resist and leaving the said blanket-coating where it is upon said chromium layer; and dry etching said chromium layer while using the remaining said blanket-coating layer as an etch mask to form said chromium mask.
Claim 3
Dependent Claim
19 words
The reverse process of claim 1 wherein the said silicon dioxide layer is less than about 10 nm thick.
Claim 4
Dependent Claim
17 words
The reverse process of claim 1 wherein said cathode sputtering is carried out in an argon atmosphere.
Claim 5
Dependent Claim
51 words
The reverse process of claim 3 wherein said dry etching takes place at an operating pressure of approximately 30μ bar, an overall radio frequency power of about 0.8 kW, a cathode voltage of about 2800 V, an anode bias of about 600 V, and an argon flow of approximately 100 ml/min.
Claim 6
Dependent Claim
18 words
The reverse process of claim 1 wherein the said chromium layer is etched by means of plasma etching.
Claim 7
Dependent Claim
19 words
The reverse process of claim 5 wherein said etching takes place in a atmosphere containing chlorinated hydrocarbons and oxygen.
Claim 8
Dependent Claim
28 words
The reverse process of claim 6 wherein the said chlorinated hydrocarbon part in the gaseous atmosphere is composed of 90 vol. % trichloroethylene and 10 vol. % dichloroethylene.
Claim 9
Dependent Claim
34 words
The reverse process of claim 7 wherein said etching takes place at a power of 300 to 350 Watts, an etching gas flow of approximately 12.5 ml/min. and a pressure of approximately 0.33μ bar.
Claim 10
Dependent Claim
155 words
A reverse process for making a chromium mask comprising: providing a substrate coated with a chromium layer; applying a layer of positive resist onto the chromium layer; exposing the said resist through an exposure mask, developing the resist and removing the unwanted portions thereof; blanket coating by chemical vapor deposition a layer of a silicon dioxide material which is dry-etched more slowly than said chromium layer; said conditions of said chemical vapor deposition is such that a layer of chromium oxide in the order of nanometers in thickness forms between said chromium layer and said silicon dioxide layer resulting in superior adherence between the said chromium and silicon dioxide layers; lifting off said blanket-coating layer where it is upon said resist and leaving the said blanket-coating where it is upon said chromium layer; and dry etching said chromium layer while using the remaining said blanket-coating layer as an etch mask to form said chromium mask.
Claim 11
Dependent Claim
155 words
A reverse process for making a chromium mask comprising: providing a substrate coated with a chromium layer; applying a layer of positive resist onto the chromium layer; exposing the said resist through an exposure mask, developing the resist and removing the unwanted portions thereof; blanket coating by chemical vapor deposition a layer of a silicon dioxide material which is dry-etched more slowly than said chromium layer; said conditions of said chemical vapor deposition is such that a layer of chromium oxide in the order of nanometers in thickness forms between said chromium layer and said silicon dioxide layer resulting in superior adherence between the said chromium and silicon dioxide layers; lifting off said blanket-coating layer where it is upon said resist and leaving the said blanket-coating where it is upon said chromium layer; and dry etching said chromium layer while using the remaining said blanket-coating layer as an etch mask to form said chromium mask.
Claim 12
Dependent Claim
18 words
The reverse process of claim 9 wherein the said chromium layer is etched by means of plasma etching.
Claim 13
Dependent Claim
19 words
The reverse process of claim 10 wherein said etching takes place in a atmosphere containing chlorinated hydrocarbons and oxygen.
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) | 1987-12-18 | 1988-06-18 | 1988-12-18 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-12-18 | 1992-06-18 | 1992-12-18 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-12-18 | 1996-06-18 | 1996-12-18 | $7700.00 | Window Closed / Lapsed |