Copper Electroplating Bath Leveler Nitrogen Ratio Control
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Solution Overview
Problem
Existing electrolytic copper plating baths struggle to optimize the filling of blind via holes with copper, particularly in terms of size variability, leading to issues like voids and uneven deposition due to differences in diffusion rates of additives.
Innovation Solution
An electrolytic copper plating bath using a water-soluble copper salt, sulfuric acid, chloride ions, a brightener, and a leveler with water-soluble polymers containing quaternary and tertiary nitrogen, allowing for control of the nitrogen ratio to match the size of blind via holes, ensuring efficient and void-free filling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If a leveler with slow diffusion rate is used to suppress surface deposition, then via hole filling is improved, but current distribution deteriorates causing voids in small or deep via holes
Solution Approach 1:
The patent changes the chemical structure parameters of the leveler by introducing quaternary nitrogen atoms into the polymer chain. This structural modification alters the diffusion rate and electrostatic interaction characteristics, enabling the leveler to reach the via hole bottom while maintaining surface suppression capability, thus resolving the contradiction between filling quality and current distribution
Solution Approach 2:
The patent uses a composite leveler structure combining quaternary nitrogen-containing groups with polyether chains. This composite design integrates the surface suppression function of traditional levelers with the enhanced penetration capability provided by quaternary nitrogen, achieving both good filling and uniform current distribution
2Manufacturing precision
If the diffusion layer thickness is reduced for small diameter via holes, then surface deposition is controlled, but the difference between surface and bottom concentration becomes great causing thick via bottom
Solution Approach 1:
The patent modifies the leveler's molecular parameters by incorporating quaternary nitrogen, which changes the diffusion coefficient and electrostatic potential distribution in the diffusion layer. This enables better concentration distribution throughout the via hole depth, preventing excessive buildup at the bottom while maintaining surface control
3Manufacturing precision
If different levelers are tested for different via hole sizes, then fill plating capability is optimized, but process complexity and time increase
Solution Approach 1:
The patent creates a universal leveler formulation containing quaternary nitrogen that can effectively fill via holes across a wide range of sizes and aspect ratios. This single formulation replaces the need for multiple specialized levelers, simplifying the selection process while maintaining optimization for different via hole geometries
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 precise control over the fill plating capability, preventing voids and ensuring uniform copper deposition across various via hole sizes, enhancing the efficiency and quality of copper plating.
Implementation Method 1
Via fill plating makes use of a difference in diffusion rate between the leveler and the brightener so as to perform fill plating of copper in via holes. The diffusion rate of the leveler is slower than that of the brightener
Implementation Method 2
it is required to fill via holes with a copper plated film by electrolytic copper plating like copper damascene or via filling of printed circuit boards
Implementation Method 3
fill via holes with a copper plated film by electrolytic copper plating
Data Source
AI summary
A copper electroplating bath useful in filling non-through holes formed on a substrate which contains a water-soluble copper salt, sulfuric acid, and chloride ions and further contains a brightener, a carrier, and a leveler as additives, wherein the leveler contains at least one water-soluble polymer containing quaternary nitrogen, tertiary nitrogen, or both which are cationizable in a solution. In the copper electroplating bath, the filling power for non-through holes formed on a substrate can be easily controlled so as to fit to the size of the holes only by changing the quaternary nitrogen to tertiary nitrogen ratio of the water-soluble polymer to be used as the leveler, which enables copper electroplating of non-through holes of various sizes with a good fit to the sizes.