Palladium sulfate solution for the selective seeding of the metal interconnections on polyimide dielectrics for electroless metal deposition
AssigneeInternational Business Machines Corporation
InventorsSuryanarayana Kaja, Shyama P. Mukherjee, Eugene J. O'Sullivan, Milan Paunovic
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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.
Claims20
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.
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.
Dependencies are inferred from the claim text.