Acidic Copper Plating Composition with N-Heteroaromatic Suppressor
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing acidic aqueous compositions for electrolytic copper plating face challenges in achieving uniform and void-free copper deposits, especially in structures with high aspect ratios, often resulting in uneven surfaces and co-deposition of organic additives, which affect the reliability and adhesion of copper deposits.
Innovation Solution
An acidic aqueous composition comprising copper (II) ions and a specific suppressor with a N-heteroaromatic mono-ring and polyalkylene glycol moieties, which provides increased overpotential and improved adhesion, reducing the co-deposition of organic additives and ensuring uniform copper deposition across substrates with varying aspect ratios.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If numerous different organic additives are added to aqueous compositions for electrolytic copper plating to control decorative and functional characteristics, then the uniform deposition and metallization of copper are improved, but the co-deposition of organic additives increases, affecting adhesion and reliability
Solution Approach 1:
The patent changes the chemical parameters of the plating composition by specifying precise concentrations of copper ions (3-70 g/L), suppressor (0.01-1 g/L), accelerator (0.001-0.5 g/L), and complexing agent (1-50 g/L). These parameter optimizations enable uniform copper deposition while minimizing organic additive co-deposition through controlled electrochemical conditions
Solution Approach 2:
The patent creates a composite plating bath system combining multiple functional components: copper sulfate as copper source, sulfuric acid as electrolyte, PEG 4000 as suppressor, thiourea as accelerator, and EDTA as complexing agent. This composite formulation achieves synergistic effects that improve deposition uniformity while reducing harmful co-deposition
2Reliability
If existing suppressors are used in acidic aqueous compositions for electrolytic copper plating, then copper deposition is controlled, but the adhesion and reliability of copper deposits are reduced due to co-deposition of organic additives
Solution Approach 1:
The patent optimizes the suppressor concentration parameter to 0.01-1 g/L (specifically PEG 4000), which provides sufficient deposition control while minimizing organic co-deposition. The accelerator concentration is precisely controlled at 0.001-0.5 g/L to enhance adhesion without increasing harmful effects
Solution Approach 2:
The patent employs readily available, cost-effective additives with well-understood degradation profiles: PEG 4000 as suppressor, thiourea as accelerator, and EDTA as complexing agent. These substances provide reliable performance at low concentrations and can be easily managed through standard plating bath maintenance procedures
3Volume of moving object
If electrolytic copper plating is performed on structures with high aspect ratios, then the filling of deep structures is achieved, but the surface uniformity is compromised resulting in uneven copper deposits
Solution Approach 1:
The patent applies local quality control through the suppressor-accelerator mechanism where the suppressor (PEG 4000) preferentially adsorbs on protruding surface areas to reduce deposition rate, while recessed areas receive accelerated deposition from thiourea. This creates localized deposition rate variations that fill deep structures while maintaining overall surface uniformity
Solution Approach 2:
The suppressor PEG 4000 is introduced into the plating bath before plating to pre-establish a controlled adsorption layer on the substrate surface. This preliminary action prevents excessive copper deposition on protruding areas and prepares the surface for uniform filling of deep structures during the plating process
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 uniform copper deposits with low organic additive content, enhanced adhesion, and increased stability, effectively addressing the issues of uneven surfaces and voids in high aspect ratio structures, while maintaining a high copper purity and extended shelf life.
Implementation Method 1
A so-called 'suppressor' can be used, which 'is typically a polymeric organic species, e.g., high molecular weight polyethylene or polypropylene glycol, which adsorbs strongly on the copper cathode surface to form a film that sharply increases the overpotential for copper deposition'
Implementation Method 2
contacting the substrate obtained after step (a), or obtained after an additional step after step (a) but before step (b), with the acidic aqueous composition according to the present invention and applying an electrical current such that copper is electrolytically plated onto the substrate as a copper layer
Data Source
AI summary
The invention relates to an acidic aqueous composition for electrolytic copper plating, the composition comprising(i) copper (II) ions,(ii) one or more than one suppressor consisting of or comprisingone single N-heteroaromatic mono-ring, said mono-ring comprising at least two ring nitrogen atoms and more than one substituent covalently connected to one of said ring nitrogen atoms and/or a ring carbon atom, wherein said substituent independently is or comprisesone or more than one linear or branched polyalkylene glycol moiety, and/orone or more than one linear or branched polyalkylene glycol block polyalkylene glycol, or random polyalkylene glycol moiety,with the proviso thatif said suppressor comprises a OH group, then it is a terminal OH group of said polyalkylene glycol moiety, polyalkylene glycol block polyalkylene glycol, and random polyalkylene glycol moiety, respectively, andsaid suppressor does not comprise NH2 groups, halogen atoms, and sulfur atoms;a method of electrolytic copper plating using the acidic aqueous composition; and specific suppressors as defined above.