US3787239A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Chemical strippers and method of using
Assignee: Henley Group Inc
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Filing: 1972-07-10
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Granted: 1974-01-22
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Expires: 1992-07-10
Abstract
Abstract Strippers for removal of organic films and deposits, such as the polymeric etch resists employed in the manufacture of semiconductors from inorganic surfaces commonly encountered in the electrical and electronic industries, are composed of solutions of chromium trioxide in mixtures of strong nitric and sulfuric acids containing about 2 percent to about 20 percent water.
Inventors
- 👤 K Schroeder
- 👤 G Kelly
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 14:58
CPC Classifications
C; C04; C04B; C04B41/00; C04B41/009; C04B41/53; C04B41/5338; C04B41/5353; C04B41/80; C04B41/91; G; G03; G03F; G03F7/00; G03F7/26; G03F7/42; G03F7/422; G03F7/423; H; H01; H01B; H01B19/00; H01B19/04; H10; H10P; H10P50/00; H10P50/20; H10P50/28; H10P50/286; H10P50/287
Claims Analysis
Total Claims: 8
Claim 1
Independent Claim
116 words
A method for removing organic deposits from a surface consisting essentially of a ceramic formed from a composition selected from the group consisting of metal oxides, metals oxide complexes and mixtures thereof, said method comprising stripping said deposits from said surface with a stripping solution including from about 0.2% to not more than 2% by weight of solution of chromic acid, from about 0.3% to about 15% by weight of solution of nitric acid, from about 2% to about 20% by weight water the balance of said solution being anyhdrous sulfuric acid, said surface being etched by said solution by less than 25 Angstrom units of thickness of said surface at room temperature in 2 minutes.
Claim 2
Dependent Claim
67 words
The method of claim 2 wherein said ceramic surface is formed from a composition selected from the group consisting of silicon dioxide, titanium dioxide, kaolinite, magnesium oxide, barium titanate, lead titanate zirconate, aluminum oxide, barium ferrite, magnetoplumbite and soft magnetic ferrites having the general formula MOFe2O3 wherein M is a divalent metal ion selected from the group consiting of copper, nickel, cobalt, iron, zinc magnesium or manganese.
Claim 3
Dependent Claim
49 words
The method of claim 3 wherein said stripping solution includes from about 0.3% to less than about 0.9% chromic acid, from about 0.3% to about 5% by weight of solution of nitric acid, from about 2% to about 16% water the balance of said solution being anhydrous sulfuric acid.
Claim 4
Independent Claim
83 words
A method for removing organic deposits from a surface comprising a nitride selected from the group consisting of silicon nitride and germanium nitride, said method comprising stripping said deposits from said surface with a stripping solution including from about 0.2% to not more than 2% by weight of solution of chromic acid, from about 0.3% to about 15% by weight of solution of nitric acid, from about 2% to about 20% by weight water, the balance of said solution being anhydrous sulfuric acid.
Claim 5
Dependent Claim
30 words
The method of claim 5 wherein said stripping solution contains not more than 0.9% by weight of chromic acid and not more than about 5% by weight of nitric acid.
Claim 6
Independent Claim
98 words
A method for removing organic deposits from a conducting or semiconducting surface comprising an element selected from the group consisting of aluminum, titanium, zirconium, chromium, molybdenum, tungsten, nickel, palladium, platinum, copper, silver, gold, Silicon, germanium, tin, lead, zinc, and cadmium comprising stripping said deposits from said surface with a stripping solution including from about 0.2% to not more than 2% by weight of solution of chromic acid, from about 0.3% to about 15% by weight of solution of nitric acid, from about 2% to about 20% by weight water, the balance of said solution being anhydrous sulfuric acid.
Claim 7
Dependent Claim
29 words
The method of claim 7 wherein stripping solution contains not more than 0.9% by weight of chromic acid and not more than about 5% by weight of nitric acid.
Claim 8
Dependent Claim
20 words
The method of claim 8 wherein the elements are selected from the group consisting of aluminum, titanium, silicon and germanium.
References Cited (Backward Citations)
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US2837484A
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US3423262A
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US3523825A
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US3676219A
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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) | 1977-01-21 | 1977-07-23 | 1978-01-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-01-21 | 1981-07-23 | 1982-01-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-01-21 | 1985-07-23 | 1986-01-22 | $7700.00 | Window Closed / Lapsed |