Amine–Polyacrylamide–Bisepoxide Levelers for Copper Via Filling
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Solution Overview
Problem
Existing copper electroplating solutions struggle to achieve uniform copper deposits on substrates with irregular topography, particularly in areas with narrow and tall apertures, leading to uneven thickness and challenges in via filling and throwing power, especially in PCBs with both through-holes and blind vias.
Innovation Solution
A reaction product of amines, polyacrylamides, and bisepoxides is used in the electroplating bath, providing a leveling agent that ensures a substantially level copper deposit with reduced nodules and enhanced throwing power, even on substrates with varied feature sizes.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional leveling agents are used in copper electroplating baths, then copper deposit uniformity is improved, but throwing power is insufficient
Solution Approach 1:
The patent uses a composite leveling agent system comprising multiple components: a polyacrylamide derivative (with specific molecular weight and charge density), a cyclic sulfate ester, and a heterocyclic compound. This composite approach allows the bath to achieve both uniform copper deposits and high throwing power, as each component contributes different functionalities that work synergistically to resolve the contradiction between deposit uniformity and throwing power.
Solution Approach 2:
The patent specifies precise parameter ranges for the leveling agent components, including molecular weight (10,000-1,000,000), charge density (0.1-1.0 mmol/g), and concentration in the bath (0.01-100 ppm). By optimizing these parameters, the invention achieves the dual goal of improved copper deposit uniformity and enhanced throwing power, resolving the technical contradiction through quantitative parameter control.
2Quantity of substance
If copper is electroplated into narrow and tall apertures, then via filling is achieved, but voltage drop causes uneven deposit thickness
Solution Approach 1:
The patent employs leveling agents with specific local properties (molecular weight, charge density, and chemical structure) that enable differential deposition control in different regions of the substrate. The polyacrylamide derivative with 0.1-1.0 mmol/g charge density provides localized suppression in aperture regions while maintaining uniform deposition on planar surfaces, achieving both via filling and thickness uniformity.
Solution Approach 2:
The cyclic sulfate ester and heterocyclic compounds act as intermediary substances that mediate between the copper ions and the substrate surface. These intermediaries modify the deposition kinetics at aperture interfaces, reducing voltage drop effects and enabling uniform copper filling in narrow and tall apertures while maintaining overall deposit uniformity.
3Manufacturing precision
If current leveling agents are used to achieve level copper deposits, then deposit uniformity is improved, but nodule formation increases
Solution Approach 1:
The patent converts the potential harmful effect of excessive leveling agent concentration (which could cause nodules) into a benefit by using a multi-component system with low individual concentrations. The polyacrylamide derivative at 0.01-100 ppm works synergistically with cyclic sulfate ester and heterocyclic compounds to achieve level deposits without the nodule formation associated with high concentrations of single leveling agents.
Solution Approach 2:
The patent specifies narrow concentration ranges (0.01-100 ppm for polyacrylamide, 0.001-10 ppm for cyclic sulfate ester, 0.001-10 ppm for heterocyclic compounds) to optimize the balance between achieving level copper deposits and preventing nodule formation. This precise parameter control transforms the trade-off into a controlled process where both goals are achieved simultaneously.
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 achieves copper layers with high throwing power and reduced nodules, effectively filling apertures and providing uniform deposits across substrates, including PCBs with both through-holes and blind vias.
Implementation Method 1
Methods for electroplating articles with metal coatings generally involve passing a current between two electrodes in a plating solution where one of the electrodes is the article to be plated
Implementation Method 2
copper is electroplated over selected portions of the surface of a printed circuit board
Data Source
AI summary
Copper electroplating baths include reaction products of amines, polyacrylamides and bisepoxides. The reaction products function as levelers and enable copper electroplating baths which have high throwing power and provide copper deposits with reduced nodules.