US5045150A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Plasma etching using a bilayer mask
Assignee: National Semiconductor Corp
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Filing: 1988-06-17
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Granted: 1991-09-03
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Expires: 2008-06-17
Abstract
Abstract A bilayer mask is utilized for etching a primary layer, which may be either an aluminum metallization layer or a dielectric layer. The bilayer mask includes both a thin resist layer and a metal imaging layer. The thin resist layer provides for high resolution patterning of the metal imaging layer. The metal imaging layer, in turn, provides for durability to withstand subsequent plasma etching of the underlying primary layer.
Inventors
- 👤 James M. Cleeves
- 👤 James G. Heard
- 👤 Zoilo C. H. Tan
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 07:04
CPC Classifications
H; H10; H10P; H10P50/00; H10P50/73; H10P50/20; H10P50/26; H10P50/264; H10P50/266; H10P50/267; H10P50/28; H10P50/282; H10P50/283; H10P50/60; H10P50/66; H10P50/663; H10P50/667; H10P76/00; H10P76/20; H10P76/204; H10P76/2045
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
111 words
A method for plasma etching a primary aluminum layer formed on a semiconductor substrate, said method comprising: forming a chromium metal image layer over the primary aluminum layer, said chromium layer having a thickness sufficient to withstand subsequent plasma etching of the aluminum layer; forming a thin resist layer over the chromium metal layer; photolithographically patterning the resist to form a first mask; etching the chromium metal layer through the first mask to form a second mask; plasma etching the primary aluminum layer through the second mask under the conditions which etch the aluminum layer in preference to the chromium layer and; removing the remaining portion of the chromium metal layer.
Claim 2
Independent Claim
111 words
A method for plasma etching a primary aluminum layer formed on a semiconductor substrate, said method comprising: forming a chromium metal image layer over the primary aluminum layer, said chromium layer having a thickness sufficient to withstand subsequent plasma etching of the aluminum layer; forming a thin resist layer over the chromium metal layer; photolithographically patterning the resist to form a first mask; etching the chromium metal layer through the first mask to form a second mask; plasma etching the primary aluminum layer through the second mask under the conditions which etch the aluminum layer in preference to the chromium layer and; removing the remaining portion of the chromium metal layer.
Claim 3
Dependent Claim
24 words
A method as in claim 1, wherein the resist is a photoresist having a thickness in the range from about 0.2 to 2 μm.
Claim 4
Dependent Claim
26 words
A method as in claim 1, wherein the resist is an electron beam resist having a thickness in the range from about 0.2 to 2 μm.
Claim 5
Dependent Claim
25 words
A method as in claim 1, wherein the resist is an x-ray resist having a thickness in the range from about 0.2 to 2 μm.
Claim 6
Dependent Claim
23 words
A method as in claim 1, wherein the chromium metal layer has a thickness in the range from about 100 to 2000 Å.
Claim 7
Dependent Claim
22 words
A method as in claim 1, wherein the chromium layer is wet etched with a ceric ammonium sulfate-based etchant at room temperature.
Claim 8
Dependent Claim
16 words
A method as in claim 1, wherein the aluminum layer is etched with a chlorinated plasma.
Claim 9
Independent Claim
99 words
A method for etching an aluminum layer on a semiconductor substrate, said method comprising: forming a layer of chromium having a thickness in the range from about 500 to 1000 Å over the aluminum layer; forming a thin resist layer over the chromium layer; photolithographically patterning the resist layer to form a first mask; etching the chromium layer with a ceric ammonium sulfate-based etchant through the first mask to form a second mask; plasma etching the aluminum layer through the second mask with a chlorine plasma etchant; and removing the chromium layer subsequent to plasma etching the aluminum layer.
Claim 10
Independent Claim
99 words
A method for etching an aluminum layer on a semiconductor substrate, said method comprising: forming a layer of chromium having a thickness in the range from about 500 to 1000 Å over the aluminum layer; forming a thin resist layer over the chromium layer; photolithographically patterning the resist layer to form a first mask; etching the chromium layer with a ceric ammonium sulfate-based etchant through the first mask to form a second mask; plasma etching the aluminum layer through the second mask with a chlorine plasma etchant; and removing the chromium layer subsequent to plasma etching the aluminum layer.
Claim 11
Dependent Claim
24 words
A method as in claim 8, wherein the resist is a photoresist having a thickness in the range from about 0.2 to 2 μm.
Claim 12
Dependent Claim
26 words
A method as in claim 8, wherein the resist is an electron beam resist having a thickness in the range from about 0.2 to 2 μm.
Claim 13
Dependent Claim
25 words
A method as in claim 8, wherein the resist is an X-ray resist having a thickness in the range from about 0.2 to 2 μm.
Claim 14
Dependent Claim
16 words
A method as in claim 8, wherein the chromium layer is formed by sputtering or evaporation.
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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) | 1994-09-02 | 1995-03-04 | 1995-09-03 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-09-02 | 1999-03-04 | 1999-09-03 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-09-02 | 2003-03-04 | 2003-09-03 | $7700.00 | Window Closed / Lapsed |