Bisurea Additive Void-Free Copper Plating
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Solution Overview
Problem
Existing aqueous acidic copper plating baths used in manufacturing printed circuit boards and semiconducting substrates fail to achieve complete and void-free filling of recessed structures like blind micro vias, through silicon vias, and through glass vias with copper, while maintaining acceptable dimple sizes and uniformity across varying aspect ratios.
Innovation Solution
An aqueous copper plating bath comprising a source of copper ions, an acid, and a bisurea derivative with a specific bisurea building block structure, free of intentionally added zinc ions, is used for electrolytic deposition, allowing for uniform filling of recessed structures without voids or excessive dimples.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional additives are used in aqueous copper plating baths, then the plating process can proceed, but complete and void-free filling of recessed structures cannot be achieved
Solution Approach 1:
The patent changes the chemical parameters of the plating bath by introducing bisurea derivatives with specific molecular structures (formula I) that have distinct properties from conventional additives. These parameter changes in additive chemistry enable complete void-free filling of recessed structures while maintaining process reliability.
Solution Approach 2:
The invention uses composite additive systems comprising bisurea derivatives combined with other plating bath components (copper ions, acids, and optionally zinc ions). This composite approach creates synergistic effects that achieve superior filling quality without voids, resolving the contradiction between filling quality and reliability.
2Manufacturing precision
If copper deposition is increased to fill recessed structures completely, then filling quality improves, but dimple size on planar substrate areas becomes excessive
Solution Approach 1:
The bisurea derivative additives provide local quality control by differentiating the deposition behavior on recessed structures versus planar substrate areas. The additive concentration and molecular structure are optimized to promote complete filling in recesses while limiting excessive copper deposition on planar areas, thus controlling dimple size within acceptable limits.
Solution Approach 2:
The patent adjusts deposition parameters through the use of bisurea derivatives, controlling the distribution of copper deposition across different substrate topographies. This parameter control enables achieving complete filling without creating excessive dimples, resolving the shape quality contradiction.
3Manufacturing precision
If conventional plating baths are used, then the process is simple, but uniform layer distribution across structures with different aspect ratios cannot be achieved
Solution Approach 1:
The bisurea derivative additives exhibit multi-functionality, simultaneously addressing uniform layer distribution across varying aspect ratios while maintaining process simplicity. The additive system provides universal performance across different structural geometries without requiring complex multi-component formulations, resolving the contradiction between precision and complexity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution enables complete and void-free filling of recessed structures with copper, maintaining acceptable dimple sizes and achieving uniform layer distribution across structures with different aspect ratios, meeting the stringent requirements of advanced printed circuit board and semiconducting substrate manufacturing.
Implementation Method 1
aqueous copper plating bath for electrolytic copper or copper alloy deposition
Implementation Method 2
electrolytic deposition of copper
Data Source
AI summary
The present invention relates to bisurea derivatives and their use in aqueous plating baths for copper and copper alloy deposition in the manufacture of printed circuit boards, IC substrates, semiconducting and glass devices for electronic applications. The plating bath according to the present invention comprises at least one source of copper ions and a bisurea derivative. The plating bath is particularly useful for filling recessed structures with copper and build-up of pillar bump structures.