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US 8,916,448 B2Granted
Metal to metal bonding for stacked (3D) integrated circuits
AssigneeInternational Business Machines Corporation
InventorsTien-Jen Cheng, Mukta G. Farooq, John A. Fitzsimmons
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Abstract
The present invention provides a stabilized fine textured metal microstructure that constitutes a durable activated surface usable for bonding a 3D stacked chip. A fine-grain layer that resists self anneal enables metal to metal bonding at moderate time and temperature and wider process flexibility.
Claims20
A method to enable metal to metal bonding comprising:
- plating a bonding layer upon a metal surface;
- annealing the bonding layer with the metal surface, wherein subsequent to annealing, an average grain size of said bonding layer is smaller than an average grain size of said metal surface.
A method to form a metallic bond between a first metal structure and a second metal structure comprising:
- holding said first metal structure and said second metal structure together at less than 350° C. to form said metallic bond at an interface, wherein said interface includes a metal deposition inhibitor at a first concentration at least one order of magnitude higher than a second concentration of said metal deposition inhibitor in either of said first metal structure and said second metal structure.
A 3D structure comprising:
- a first die bonded to a second die, wherein the first die comprises a metal structure formed within a dielectric layer disposed on a semiconductor substrate within which at least one semiconductor device is formed, and wherein the second die comprises a semiconductor substrate and a metal contact pad, and;
- a metallic bond at an interface between said metal structure and said contact pad, the composition of said interface comprising a metal deposition inhibitor that inhibits plating, a first concentration of said metal deposition inhibitor at the interface being at least one order of magnitude higher than a second concentration of said metal deposition inhibitor within either of said metal structure or said contact pad.
Dependencies are inferred from the claim text.