US4707377A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Copper plating
Assignee: International Business Machines Corp
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Filing: 1986-10-27
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Granted: 1987-11-17
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Expires: 2006-10-27
Abstract
Abstract Copper is plated onto a substrate from an electroless plating bath having a mix potential relative to a saturated calomel electrode of about minus 630 to about minus 675 millivolts at a temperature of about 73° C. The mix potential of the bath is monitored and adjusted during the plating to maintain it at about minus 630 to about minus 675 millivolts with respect to a calomel electrode at a temperature of about 73° C. The number of of plating void defects is thereby reduced.
Inventors
- 👤 Robert J. Capwell
- 👤 Ronald A. Kaschak
- 👤 Donald G. McBride
- 👤 Robert G. Rickert
- 👤 Donald P. Seraphim
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 12:58
CPC Classifications
C; C23; C23C; C23C18/00; C23C18/16; C23C18/31; C23C18/38; C23C18/40; H; H05; H05K; H05K3/00; H05K3/10; H05K3/18; H05K3/181; H05K3/187
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
176 words
A process for plating copper from an electroless plating bath onto a substrate to reduce plating voids comprising: (a) providing an electroless aqueous copper plating bath containing a source of cupric ion, a reducing agent for the cupric ion, and a complexing agent for the cupic ion in amounts effective to plate copper onto said substrate, wherein said bath, at a temperature of about 73° C., has a mix potential relative to a saturated calomel electrode of about minus 630 to about minus 675 millivolts; (b) providing said substrate in said plating bath; (c) monitoring the mix potential of said bath during plating including placing in said bath during plating and at the plating temperature a reference electrode; and (d) adjusting the composition of said bath to maintain the mix potential during plating at about minus 630 to about minus 675 millivolts with respect to a saturated calomel electrode at a temperature of about 73° C.; and (e) wherein the temperature of the bath is maintained between about 70° C. and 80° C. during the plating.
Claim 2
Dependent Claim
176 words
A process for plating copper from an electroless plating bath onto a substrate to reduce plating voids comprising: (a) providing an electroless aqueous copper plating bath containing a source of cupric ion, a reducing agent for the cupric ion, and a complexing agent for the cupic ion in amounts effective to plate copper onto said substrate, wherein said bath, at a temperature of about 73° C., has a mix potential relative to a saturated calomel electrode of about minus 630 to about minus 675 millivolts; (b) providing said substrate in said plating bath; (c) monitoring the mix potential of said bath during plating including placing in said bath during plating and at the plating temperature a reference electrode; and (d) adjusting the composition of said bath to maintain the mix potential during plating at about minus 630 to about minus 675 millivolts with respect to a saturated calomel electrode at a temperature of about 73° C.; and (e) wherein the temperature of the bath is maintained between about 70° C. and 80° C. during the plating.
Claim 3
Dependent Claim
18 words
The process of claim 1 wherein said mix potential is about minus 630 to about minus 650 millivolts.
Claim 4
Dependent Claim
14 words
The process of claim 1 wherein said mix potential is about minus 630 millivolts.
Claim 5
Dependent Claim
14 words
The process of claim 1 wherein the source of cupric ion is cupric sulfate.
Claim 6
Dependent Claim
11 words
The process of claim 1 wherein the reducing agent is formaldehyde.
Claim 7
Dependent Claim
17 words
The process of claim 1 wherein said complexing agent is ethylene diamine tetraacetic acid or salt thereof.
Claim 8
Dependent Claim
12 words
The process of claim 1 wherein said bath also contains cyanide ion.
Claim 9
Dependent Claim
24 words
The process of claim 1 wherein the temperature of the bath is maintained between about 70° C. and about 75° C. during the plating.
Claim 10
Dependent Claim
19 words
The process of claim 1 wherein the temperature of the bath is maintained at about 73° C. during plating.
Claim 11
Dependent Claim
39 words
The process of claim 1 wherein said plating bath consists essentially of a source of cupric ion, a reducing agent for the cupric ion, a complexing agent for the cupric ion, a pH adjustor, a surfactant, and cyanide ion.
Claim 12
Dependent Claim
43 words
The process of claim 1 wherein composition of the bath is adjusted to maintain said mix potential during plating by adjusting at least one member of the group of cupric ion content, reducing agent content, oxygen content, complexing agent, and cyanide ion content.
Claim 13
Dependent Claim
24 words
The process of claim 1 which comprises adjusting the bath to maintain said mix potential during plating by removal of contaminates from the bath.
Claim 14
Dependent Claim
17 words
The process of claim 1 wherein the pH of said bath is about 11.6 to about 11.8.
References Cited (Backward Citations)
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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) | 1990-11-16 | 1991-05-18 | 1991-11-17 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1994-11-16 | 1995-05-18 | 1995-11-17 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1998-11-16 | 1999-05-18 | 1999-11-17 | $7700.00 | Window Closed / Lapsed |