Guanidine Leveller for Uniform Copper Pillar Plating
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Solution Overview
Problem
Existing aqueous acidic copper plating baths for electrolytic deposition of copper in printed circuit board and IC substrate manufacturing result in inhomogeneous pillar size distribution and high organic impurities, leading to reduced conductivity and contact issues between components.
Innovation Solution
An aqueous acidic copper plating bath comprising a source of copper ions, an acid, and a guanidine compound with specific structural units, which acts as a leveller to achieve uniform copper deposition and minimize voids, ensuring homogeneous pillar size distribution and high conductivity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If polyethylenimines are used as levellers in copper electroplating baths, then convection independence is improved, but organic impurity content increases
Solution Approach 1:
The patent changes the chemical composition parameter by replacing polyethylenimine levellers with guanidine compound levellers. This substitution maintains the convection-independent levelling effect while fundamentally altering the chemical nature of the additive to reduce organic impurity incorporation in the copper deposit.
Solution Approach 2:
The guanidine compound serves as a consumable additive that performs its levelling function and can be replaced or regenerated. The patent implies that using guanidine compounds may offer economic advantages and reduced impurity accumulation compared to polyethylenimines, aligning with the principle of using cost-effective, replaceable substances.
2Manufacturing precision
If urea polymers are used as levellers, then deposition uniformity is improved, but pillar growth is reduced
Solution Approach 1:
The patent changes the molecular structure parameter of the leveller by using guanidine compounds with specific structural units instead of urea polymers. This structural modification allows the leveller to maintain deposition uniformity while avoiding the growth suppression effect observed with urea polymers, likely due to differences in how these compounds interact with copper ions and the growing deposit.
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 void-free copper deposition with uniform pillar height distribution and reduced organic impurities, enhancing the conductivity and reliability of copper layers in semiconductor applications.
Implementation Method 1
aqueous acidic copper plating bath for electrolytic deposition of copper or copper alloys
Implementation Method 2
electrolytic deposition of copper
Data Source
AI summary
The present invention relates to aqueous acidic 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, at least one acid and at least one guanidine compound. The plating bath is particularly useful for plating recessed structures with copper and build-up of copper pillar bump structures.