US4995942A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Effective near neutral pH etching solution for molybdenum or tungsten
Assignee: International Business Machines Corp
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Filing: 1990-04-30
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Granted: 1991-02-26
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Expires: 2010-04-30
Abstract
Abstract A neutral or near neutral pH etching solution for effectively etching molybdenum and tungsten including: an aqueous ferricyanide ion solution, a soluble molybdate or tungstate, and an essential compound such that upon combination of said soluble molybdate or tungstate and said essential compound, a heteropoly compound is formed in which said essential compound contributes at least one heteroatom to said heteropoly compound. The etching solution is most preferably used for etching molybdenum or tungsten which is adhered or proximate to a base-sensitive material.
Inventors
- 👤 Lawrence D. David
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 20:48
CPC Classifications
C; C23; C23F; C23F1/00; C23F1/10; C23F1/14
Claims Analysis
Total Claims: 23
Claim 1
Independent Claim
62 words
A neutral or near neutral pH etching solution for effectively etching molybdenum and tungsten comprising: an aqueous ferricyanide ion solution, a soluble molybdate or tungstate, and an essential compound such that upon combination of said soluble molybdate or tungstate and said essential compound, a heteropoly compound is formed in which said essential compound contributes at least one heteroatom to said heteropoly compound.
Claim 2
Dependent Claim
62 words
A neutral or near neutral pH etching solution for effectively etching molybdenum and tungsten comprising: an aqueous ferricyanide ion solution, a soluble molybdate or tungstate, and an essential compound such that upon combination of said soluble molybdate or tungstate and said essential compound, a heteropoly compound is formed in which said essential compound contributes at least one heteroatom to said heteropoly compound.
Claim 3
Dependent Claim
18 words
The etching solution of claim 1 wherein said essential compound is phosphoric acid and said heteroatom is phosphorus.
Claim 4
Dependent Claim
18 words
The etching solution of claim 1 wherein said essential compound is sulfurous acid and said heteroatom is sulfur.
Claim 5
Dependent Claim
13 words
The etching solution of claim 1 wherein said soluble molybdate is sodium molybdate.
Claim 6
Dependent Claim
21 words
The etching solution of claim 4 wherein the pH of said solution is in the range of about 7 to 8.
Claim 7
Dependent Claim
13 words
The etching solution of claim 1 wherein said soluble tungstate is sodium tungstate.
Claim 8
Dependent Claim
21 words
The etching solution of claim 6 wherein the pH of said solution is in the range of about 6 to 8.
Claim 9
Dependent Claim
12 words
The etching solution of claim 1 further comprising a charge balancing species.
Claim 10
Dependent Claim
23 words
The etching solution of claim 8 wherein said charge balancing species is selected from the group consisting of sodium, potassium, and ammonium ions.
Claim 11
Dependent Claim
14 words
The etching solution of claim 1 wherein said etching solution is at room temperature.
Claim 12
Independent Claim
88 words
A method of effectively etching molybdenum or tungsten from a composite material comprising molydenum or tungsten adhered to a base-sensitive material without damaging the material comprising the steps of: contacting the composite with a neutral or near neutral pH etching solution comprising: an aqueous ferricyanide ion solution, a soluble molybdate or tungstate, and an essential compound such that upon combination of said soluble molybdate or tungstate and said essential compound, a heteropoly compound is formed in which said compound ingredient contributes at least one heteroatom to said heteropolycompound.
Claim 13
Independent Claim
88 words
A method of effectively etching molybdenum or tungsten from a composite material comprising molydenum or tungsten adhered to a base-sensitive material without damaging the material comprising the steps of: contacting the composite with a neutral or near neutral pH etching solution comprising: an aqueous ferricyanide ion solution, a soluble molybdate or tungstate, and an essential compound such that upon combination of said soluble molybdate or tungstate and said essential compound, a heteropoly compound is formed in which said compound ingredient contributes at least one heteroatom to said heteropolycompound.
Claim 14
Dependent Claim
17 words
The method of claim 11 wherein said essential compound is phosphoric acid and said heteroatom is phosphorus.
Claim 15
Dependent Claim
17 words
The method of claim 11 wherein said essential compound is sulfurous acid and said heteroatom is sulfur.
Claim 16
Dependent Claim
12 words
The method of claim 11 wherein said soluble molybdate is sodium molybdate.
Claim 17
Dependent Claim
20 words
The method of claim 14 wherein the pH of said solution is in the range of about 7 to 8.
Claim 18
Dependent Claim
12 words
The method of claim 11 wherein said soluble tungstate is sodium tungstate.
Claim 19
Dependent Claim
20 words
The method of claim 16 wherein the pH of said solution is in the range of about 6 to 8.
Claim 20
Dependent Claim
11 words
The method of claim 11 further comprising a charge balancing species.
Claim 21
Dependent Claim
22 words
The method of claim 18 wherein said charge balancing species is selected from the group consisting of sodium, potassium, and ammonium ions.
Claim 22
Dependent Claim
13 words
The method of claim 11 wherein said etching solution is at room temperature.
Claim 23
Dependent Claim
20 words
The method of claim 11 further comprising the step of introducing ozone into said etching solution to rejuvenate said solution.
References Cited (Backward Citations)
US4747907A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1994-02-25 | 1994-08-27 | 1995-02-26 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-02-25 | 1998-08-27 | 1999-02-26 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-02-25 | 2002-08-27 | 2003-02-26 | $7700.00 | Window Closed / Lapsed |