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US 6,616,967 B1Granted
Method to achieve continuous hydrogen saturation in sparingly used electroless nickel plating process
AssigneeTexas Instruments Incorporated
InventorHoward R. Test
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Abstract
An improved wire bonding process for copper-metallized integrated circuits is provided by a nickel layer that acts as a barrier against up-diffusing copper. In accordance with the present invention the nickel bath is placed and remains in hydrogen saturation by providing a piece of metal that remains in the nickel plating tank before and during the plating process.
Claims12
A method for forming metallurgical connections between wires containing gold and bond pads positioned on integrated circuits having copper interconnecting metallization, comprising the steps of:
- placing a nickel bath into a state of hydrogen saturation by plating a sufficient surface of dummy material and by maintaining the bath in hydrogen saturation by placing a plating specimen of sufficient size metal in the nickel bath before the following steps of:
- activating the surface of said copper interconnecting surface, depositing seed metal,
- plating a layer of nickel barrier metal that resists copper diffusion by electroless deposition in said nickel bath that is in continuous hydrogen saturation;
- and
- plating a layer of bondable metal by electroless or immersion deposition.
2 more elements
Dependencies are inferred from the claim text.