US4710261A
Expired / Lapsed
US
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Apparatus and method for maintaining a uniform etching solution composition
Assignee: Intersil Corp
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Filing: 1987-01-28
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Granted: 1987-12-01
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Expires: 2007-01-28
Abstract
Abstract An apparatus and method are disclosed for replenishing the depleted component of a multicomponent etching solution. A portion of the etching solution is analyzed with a UV detector to determine the concentration of the depleted component. An output signal is produced by the UV detector which is a function of the depleted component's concentration. In response to this output signal, a microprocessor is used to control the amount of make-up solution, enriched with the depleted component of the multicomponent etching solution, which is added to the etching solution. With the use of this system, a substantially uniform etch bath composition is maintained.
Inventors
- 👤 Timothy A. Dennis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 11:34
CPC Classifications
C; C23; C23F; C23F1/00; H; H10; H10P; H10P50/00; H10P50/60; H10P50/66; H10P50/663; H10P50/667
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
102 words
A method of etching at a substantially uniform rate a metallization layer disposed on a substrate, comprising the steps of: contacting said metallization layer with an etching solution comprising HNO 3 and H 3 PO 4 ; sampling at least a portion of said etching solution with a UV detector to produce an output signal which is a function of the HNO 3 concentration; and delivering a make-up solution comprising HNO 3 and H 3 PO 4 in controlled amounts responsive to said output signal to said etching solution, whereby a substantially uniform HNO 3 concentration is maintained within said etching solution.
Claim 2
Independent Claim
102 words
A method of etching at a substantially uniform rate a metallization layer disposed on a substrate, comprising the steps of: contacting said metallization layer with an etching solution comprising HNO 3 and H 3 PO 4 ; sampling at least a portion of said etching solution with a UV detector to produce an output signal which is a function of the HNO 3 concentration; and delivering a make-up solution comprising HNO 3 and H 3 PO 4 in controlled amounts responsive to said output signal to said etching solution, whereby a substantially uniform HNO 3 concentration is maintained within said etching solution.
Claim 3
Dependent Claim
18 words
A method as recited in claim 1 wherein said UV detector has a wavelength of about 280 nanometers.
Claim 4
Dependent Claim
33 words
A method as recited in claim 3 wherein said make-up solution comprises about 10-30% by volume HNO 3 (70% by weight) and about 70-90% by volume H 3 PO 4 (85% by weight).
Claim 5
Dependent Claim
33 words
A method as recited in claim 3 wherein said make-up solution comprises about 15% by volume HNO 3 (70% by weight) and about 85% by volume H 3 PO 4 (85% by weight).
Claim 6
Dependent Claim
32 words
A method as recited in claim 4 wherein said etching solution comprises about 96.5% by volume H 3 PO 4 (85% by weight) and 3.5% by volume HNO 3 (70% by weight).
Claim 7
Dependent Claim
24 words
A method as recited in claim 5 wherein said metallization layer comprises an aluminum-silicon alloy or aluminum and said substrate is a semiconductor wafer.
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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) | 1990-11-30 | 1991-06-01 | 1991-12-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-30 | 1995-06-01 | 1995-12-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-30 | 1999-06-01 | 1999-12-01 | $7700.00 | Window Closed / Lapsed |