Copper Plating Dome Height Control via Chloride Ion Concentration
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Solution Overview
Problem
In semiconductor manufacturing, controlling the dome height of copper bumps independently of their height is challenging, especially when using electroplating methods, as it affects the subsequent polishing and reflow processes, and existing methods struggle to achieve precise control over dome height without influencing bump height.
Innovation Solution
A copper plating method involving a plating solution with chloride ions at a concentration between 100 mg/dm3 to 300 mg/dm3, combined with controlled current density and temperature, and agitation, to achieve a desired dome height even when bump heights are high, such as over 100 μm.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Length of stationary object
If electroplating is used to form copper bumps with high bump height, then the bump height is sufficient for bonding, but the dome height becomes difficult to control independently
Solution Approach 1:
The patent applies parameter changes by adjusting the chloride ion concentration in the plating solution to a specific range (100-300 mg/dm³) to independently control dome height while maintaining bump height. This chemical parameter modification enables separate control of dome and bump dimensions, resolving the contradiction between achieving sufficient bump height and maintaining precise dome height control.
2Productivity
If dome height is reduced to shorten polishing time, then productivity improves, but bump height may be insufficient for reliable bonding
Solution Approach 1:
By modifying the chloride ion concentration parameter in the plating solution, the patent enables formation of bumps with appropriate dome heights that minimize polishing requirements while maintaining sufficient bump height for reliable bonding. This parameter optimization achieves both reduced polishing time and ensured bonding reliability simultaneously.
3Manufacturing precision
If chloride ion concentration is increased to control dome height, then dome height control improves, but plating solution composition becomes more complex
Solution Approach 1:
The patent uses chloride ion concentration as a controlled parameter within a specific range (100-300 mg/dm³) to achieve precise dome height control. While this adds a compositional parameter, it builds upon existing plating solution formulations and provides a quantifiable control mechanism that balances precision with practical solution 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
This method allows for precise control of dome height, reducing the time required for polishing and ensuring uniformity in bump formation, thereby enhancing the accuracy and reliability of the bonding process.
Implementation Method 1
passing an electric current between an anode and the substrate, both immersed in the plating solution, thereby plating the substrate to form bumps
Data Source
AI summary
A plating method which can achieve a desired dome height is disclosed. The method includes: preparing correlation data showing a relationship between proportion of dome height to bump height and concentration of chloride ions; producing a plating solution containing chloride ions at a concentration which has been selected based on a desired proportion of dome height to bump height and on the correlation data, the selected concentration being in a range of 100 mg/dm3 to 300 mg/dm3; immersing a substrate in the plating solution; and passing an electric current between an anode and the substrate, both immersed in the plating solution, thereby plating the substrate to form bumps.