Copper Electroplating via Reverse Pulse Plating for Rectangular Trenches
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Solution Overview
Problem
Current copper electroplating methods struggle to simultaneously fill blind micro vias and trenches with copper while achieving the desired rectangular cross-sectional shape, especially as feature sizes decrease and aspect ratios increase, with existing methods often resulting in insufficient trench cross-sectional line shapes.
Innovation Solution
A copper electroplating method involving an aqueous acidic copper electrolyte with a leveler additive, such as ureylene polymers or peptides functionalized with polyalkylene glycol residues, and a current pulse cycle consisting of a forward and reverse current pulse, where the reverse charge fraction is between 0.1% to 5% of the forward charge, to achieve simultaneous filling of blind micro vias and formation of copper trenches with a rectangular cross-sectional shape.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional electroplating methods are used to fill blind micro vias, then the vias can be filled with copper, but the trenches do not achieve the desired rectangular cross-sectional shape
Solution Approach 1:
The patent applies reverse pulse plating with periodic current reversal to achieve rectangular trench cross-sections while maintaining BMV filling quality. The periodic switching between forward and reverse current creates controlled deposition patterns that form rectangular shapes in trenches while ensuring complete via filling.
Solution Approach 2:
The patent modifies plating parameters including current density (20-100 A/dm² for reverse pulse), pulse duration (0.05-1 ms for reverse pulse), and electrolyte composition (adding leveler additives) to simultaneously achieve rectangular trench cross-sections and complete BMV filling. These parameter changes resolve the contradiction between shape precision and filling reliability.
2Productivity
If feature sizes are reduced and aspect ratios are increased for miniaturization, then electronic component density is improved, but the requirements for BMV filling and trench shape become more demanding
Solution Approach 1:
The reverse pulse plating method uses periodic current reversal with specific duty cycles to control copper deposition in high aspect ratio vias and narrow trenches. This periodic action maintains uniform deposition even when features are miniaturized, preserving manufacturing precision while enabling higher component density.
Solution Approach 2:
The patent introduces leveler additives as intermediaries in the electrolyte that mediate the deposition process during miniaturization. These additives help maintain uniform current distribution and deposition rates, ensuring filling quality and trench shape are preserved even as feature sizes decrease and aspect ratios increase.
3Productivity
If different features such as BMVs and trenches are plated in one step, then processing efficiency is improved, but achieving both required filling quality and rectangular trench shape becomes difficult
Solution Approach 1:
The reverse pulse plating method serves multiple functions simultaneously: it fills BMVs completely, forms rectangular trench cross-sections, and maintains uniform deposition across different feature types. This multi-functionality enables single-step plating of diverse features while preserving manufacturing precision for each feature type.
Solution Approach 2:
The patent optimizes plating parameters including electrolyte composition (adding leveler additives like polyethylene glycol), current density, and pulse timing to enable simultaneous achievement of BMV filling quality and rectangular trench shapes in one processing step, thereby maintaining precision while improving productivity.
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 effectively fills blind micro vias and forms copper trenches with a rectangular cross-sectional shape, improving the filling quality and meeting the increased requirements of miniaturized electronic components, while allowing for economical one-step processing of different features.
Implementation Method 1
copper electroplating method
Implementation Method 2
electrodeposition of copper
Implementation Method 3
applying to the substrate an electrical current, comprising at least one current pulse cycle consisting of one forward current pulse and one reverse current pulse
Data Source
Figure 1~3
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AI summary
The method for copper electroplating according to the present invention comprises an aqueous acidic copper plating bath containing a leveler additive which forms copper trenches having a cross-sectional round shape under direct current plating conditions, and at least one reverse current pulse cycle consisting of one forward current pulse and one reverse current pulse wherein the fraction of the reverse charge to the forward charge applied to the substrate in said at least one current pulse cycle ranges between 0.1 to 5 %. The method is particularly suitable for simultaneously filling blind micro vias and plating trenches with a rectangular cross-sectional shape.