US4940510A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method of etching in the presence of positive photoresist
Assignee: Hewlett Packard Development Co LP
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Filing: 1987-06-01
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Granted: 1990-07-10
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Expires: 2007-06-01
Abstract
Abstract A wet chemical etchant for etching chromium films that have been patterned with positive photoresist comprising about 3 to about 9 grams potassium hydroxide per liter of water and about 15 to about 25 grams potassium permanganate per liter of water.
Inventors
- 👤 Roy J. Burt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 02:35
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14; C23F1/32; C23F1/38; H; H05; H05K; H05K3/00; H05K3/02; H05K3/06; H05K3/061; H05K3/064; H05K3/067
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
54 words
A method for etching chromium in the presence of positive photoresist comprising contacting a chromium film which has been patterned with positive photoresist with a solution consisting essentially of about 3 to about 9 grams potassium hydroxide per liter of water and about 15 to about 25 grams potassium permanganate per liter of water.
Claim 2
Independent Claim
54 words
A method for etching chromium in the presence of positive photoresist comprising contacting a chromium film which has been patterned with positive photoresist with a solution consisting essentially of about 3 to about 9 grams potassium hydroxide per liter of water and about 15 to about 25 grams potassium permanganate per liter of water.
Claim 3
Dependent Claim
33 words
The method according to claim 1 where said solution consists essentially of about 5 grams of potassium hydroxide per liter of water and about 20 grams of potassium permanganate per liter of water.
Claim 4
Dependent Claim
21 words
The method according to claim 1 where said etching is conducted at a temperature ranging from about 20°C. to about 50°C.
Claim 5
Dependent Claim
11 words
The method according to claim 2 where said temperature is 21°C.
Claim 6
Dependent Claim
19 words
The method according to claim 1 where said chromium film has a thickness of less than about 500 angstroms.
Claim 7
Independent Claim
55 words
A method for etching chromium in a chromium on copper thin film patterned with positive photoresist comprising contacting the chromium layer of said film with a solution consisting essentially of about 3 to about 9 grams potassium hydroxide per liter of water and about 15 to about 25 grams potassium permanganate per liter of water.
Claim 8
Independent Claim
55 words
A method for etching chromium in a chromium on copper thin film patterned with positive photoresist comprising contacting the chromium layer of said film with a solution consisting essentially of about 3 to about 9 grams potassium hydroxide per liter of water and about 15 to about 25 grams potassium permanganate per liter of water.
Claim 9
Dependent Claim
33 words
The method according to claim 6 where said solution consists essentially of about 5 grams of potassium hydroxide per liter of water and about 20 grams of potassium permanganate per liter of water.
Claim 10
Dependent Claim
22 words
The method according to claim 7 where said etching is at a temperature ranging from about 20° C. to about 50° C.
Claim 11
Dependent Claim
12 words
The method according to claim 8 where said temperature is 21° C.
Claim 12
Dependent Claim
19 words
The method according to claim 6 where said chromium film has a thickness of less than about 500 angstroms.
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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) | 1993-07-09 | 1994-01-08 | 1994-07-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1997-07-09 | 1998-01-08 | 1998-07-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2001-07-09 | 2002-01-08 | 2002-07-10 | $7700.00 | Window Closed / Lapsed |