US5380560A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Palladium sulfate solution for the selective seeding of the metal interconnections on polyimide dielectrics for electroless metal deposition
Assignee: International Business Machines Corp
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Filing: 1992-07-28
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Granted: 1995-01-10
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Expires: 2012-07-28
Abstract
Abstract A method of selectively seeding or activating metal interconnections patterned on polyimide dielectric surfaces using an aqueous solution of palladium sulfate, palladium perchlorate, palladium trifluoromethane sulfonate, palladium nitrate or other palladium salts having poorly coordinating counter ions. This strongly selective seeding and the corresponding ability to reliably remove all traces of the seeding material from the polyimide surface eliminates shorting, bridging and reduction of breakdown voltage during electroless plating of a thin layer of nickel or cobalt.
Inventors
- 👤 Suryanarayana Kaja
- 👤 Shyama P. Mukherjee
- 👤 Eugene J. O'Sullivan
- 👤 Milan Paunovic
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 18:37
CPC Classifications
H; H05; H05K; H05K3/00; H05K3/46; H05K3/4644; H05K3/465; C; C23; C23C; C23C18/00; C23C18/16; C23C18/1601; C23C18/1603; C23C18/1607; C23C18/1608; C23C18/1612; C23C18/1633; C23C18/1635; C23C18/1637; C23C18/18; C23C18/20; C23C18/28; C23C18/30; C23C18/31; C23C18/32; H05K3/22; H05K3/24; H05K3/244; H05K2201/00; H05K2201/01; H05K2201/0137; H05K2201/0154; H05K2201/07; H05K2201/0753; H05K2201/0761; H05K2203/00; H05K2203/07; H05K2203/0703; H05K2203/0716; H05K2203/072; H05K2203/0756; H05K2203/0766; H05K3/38; H05K3/382; H05K3/384; H05K3/388
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
88 words
A method of selectively seeding a surface of a metal or alloy at a polyimide surface for electroless deposition of a further metal comprising the steps of: seeding said surface of said metal using an activating solution selected from the consisting of palladium sulfate, palladium perchlorate, palladium trifluoromethane sulfonate, palladium nitrate, and palladium fluoroborate; removing palladium ions from said polyimide by rinsing said polyimide with a rinse selected from the group consisting of water and sodium citrate complexant; and plating said further metal or alloy on said metal.
Claim 2
Independent Claim
88 words
A method of selectively seeding a surface of a metal or alloy at a polyimide surface for electroless deposition of a further metal comprising the steps of: seeding said surface of said metal using an activating solution selected from the consisting of palladium sulfate, palladium perchlorate, palladium trifluoromethane sulfonate, palladium nitrate, and palladium fluoroborate; removing palladium ions from said polyimide by rinsing said polyimide with a rinse selected from the group consisting of water and sodium citrate complexant; and plating said further metal or alloy on said metal.
Claim 3
Dependent Claim
23 words
A method as recited in claim 1 wherein said step of plating is performed using nickel or cobalt which can be electrolessly deposited.
Claim 4
Dependent Claim
32 words
A method as recited in claim 1 wherein said step of seeding is performed using an activating solution comprising 0.01 to 1.0 gram/liter palladium sulfate in 2-15 percent by volume sulfuric acid.
Claim 5
Dependent Claim
42 words
A method as recited in claim 1 wherein said step of plating is performed at a temperature in the range of 50° C. to 90° C. and pH in the range of 7 to 10 for a time period of 5-45 minutes.
Claim 6
Dependent Claim
22 words
A method as recited in claim 1 including the further step of cleaning said surface of said metal and said polyimide surface.
Claim 7
Dependent Claim
18 words
A method as recited in claim 5 wherein said step of cleaning is performed using 10% sulfuric acid.
Claim 8
Dependent Claim
32 words
The method of claim 1 wherein said step of seeding is performed with an activating solution selected from the group consisting of palladium perchlorate, palladium trifluoromethane sulfonate, palladium nitrate, and palladium fluoroborate.
Claim 9
Independent Claim
129 words
A method of electroless plating comprising the sequential steps of: applying a blanket layer of chromium-copper to a substrate; applying a polyimide underlayer on said layer of chromium-copper; applying an overlayer of polyimide on said polyimide underlayer; patterning said overlayer of polyimide so as to form trenches in said overlayer and in said polyimide underlayer applying a blanket layer of chromium or chromium-copper; depositing a blanket layer of metal, whereby said trenches are completely filled; planarizing said blanket layer of metal, whereby metal is removed from areas above said patterned polyimide overlayer outside said trenches; seeding remaining metal using an activating solution comprising a palladium salt having poorly coordinating counter ions; removing palladium ions from said polyimide overlayer; plating nickel or cobalt on said remaining metal by electroless deposition.
Claim 10
Independent Claim
129 words
A method of electroless plating comprising the sequential steps of: applying a blanket layer of chromium-copper to a substrate; applying a polyimide underlayer on said layer of chromium-copper; applying an overlayer of polyimide on said polyimide underlayer; patterning said overlayer of polyimide so as to form trenches in said overlayer and in said polyimide underlayer applying a blanket layer of chromium or chromium-copper; depositing a blanket layer of metal, whereby said trenches are completely filled; planarizing said blanket layer of metal, whereby metal is removed from areas above said patterned polyimide overlayer outside said trenches; seeding remaining metal using an activating solution comprising a palladium salt having poorly coordinating counter ions; removing palladium ions from said polyimide overlayer; plating nickel or cobalt on said remaining metal by electroless deposition.
Claim 11
Dependent Claim
23 words
A method as recited in claim 8 wherein said step of removing is performed by rinsing said polyimide using a sodium citrate complexant.
Claim 12
Dependent Claim
21 words
A method as recited in claim 8 wherein said step of removing is performed by rinsing said polyimide using deionized water.
Claim 13
Dependent Claim
20 words
A method as recited in claim 8 wherein said step of depositing is performed using a blanket layer of copper.
Claim 14
Dependent Claim
32 words
A method as recited in claim 8 wherein said step of seeding is performed using an activating solution comprising 0.01 to 1.0 gram/liter palladium sulfate in 2-15 percent by volume sulfuric acid.
Claim 15
Dependent Claim
42 words
A method as recited in claim 8 wherein said step of plating is performed at a temperature in the range of 50° C. to 90° C. and pH in the range of 4.5 to 10 for a time period of 2-45 minutes.
Claim 16
Dependent Claim
22 words
A method as recited in claim 8 wherein said palladium salt includes palladium sulfate, palladium perchlorate, palladium trifluoromethane sulfonate or palladium nitrate.
Claim 17
Dependent Claim
31 words
A method as recited in claim 8 wherein said step of plating is performed at a temperature of 75° C. and pH of 8.0 for a time period of 2-15 minutes.
Claim 18
Dependent Claim
20 words
A method as recited in claim 8 including the further step of cleaning said remaining metal interconnections with sulfuric acid.
Claim 19
Dependent Claim
18 words
A method as recited in claim 16 wherein said step of cleaning is performed using 10% sulfuric acid.
Claim 20
Dependent Claim
55 words
A method as recited in claim 8 wherein said overlayer of polyimide is photosensitive and said patterning step includes the further steps of exposing said photosensitive polyimide overlayer to a radiation source to form a pattern; and developing said photosensitive polyimide overlayer to form trenches in said photosensitive polyimide overlayer and in said polyimide underlayer,
Claim 21
Dependent Claim
55 words
A method as recited in claim 8, wherein said palladium salt, in said activating solution, provides counter ions which are coordinating to a degree similar to the coordinating exhibited by the group of ions consisting of SO 4 - , NO 3 - , CF 3 SO 4 - , and BF 4 - .
Claim 22
Dependent Claim
26 words
A method as recited in claim 8, wherein said counter ions of said palladium salt do not form complexes or significantly react with said polyimide surface.
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| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
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| 3.5 Years (Year 4) | 1998-01-09 | 1998-07-11 | 1999-01-10 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2002-01-09 | 2002-07-11 | 2003-01-10 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2006-01-09 | 2006-07-11 | 2007-01-10 | $7700.00 | Window Closed / Lapsed |