Effect of chloride ions on the adsorption of organic additives on copper in electrolytes based on sulphuric and methanesulphonic acids

• N.P. Andreeva¹, I.A. Kuznetsov¹, A.A. Chirkunov¹, V.A. Polikarchuk², O.A. Kozaderov², N.V. Sotskaya² and Kh.S. Shikhaliev²

¹ Frumkin Institute of Physical Chemistry and Electrochemistry, Russian Academy of Sciences, 31-4, Leninsky prospect, 119071 Moscow, Russia
² Voronezh State University, Universitetskaya pl. 1, Voronezh, 394018, Russia

Abstract: This work presents a comprehensive ellipsometric study of competitive adsorption kinetics involving organic additives in acid copper electroplating solutions. The research focuses on comparing adsorption behavior of individual components and their mixtures in sulfuric acid (H₂SO₄) versus methanesulfonic acid (CH₃SO₃H) electrolytes containing chloride ions. The experimental results demonstrate significant differences in additive adsorption depending on the medium. The SPS brightener and JGB leveler show markedly higher adsorption efficiency in methanesulfonic acid solutions, while the PEG-115 and PEG-8000 inhibitors exhibit stronger adsorption in sulfuric acid. A particularly noteworthy finding reveals that chloride ions substantially enhance the adsorption of the SPS+PEG mixture in sulfuric acid but show no beneficial effect on JGB adsorption. Analysis of ternary additive mixtures reveals complex interactions between the components. The mixture containing the Avangard aromatic compound demonstrates significantly better adsorption (δΔ=–0.53° to –0.60°) compared to formulations with aliphatic SPS (δΔ=0–0.10°), highlighting the crucial importance of molecular structure in adsorption processes. The study provides a quantitative characterization of these effects through precise ellipsometric measurements of phase angle variations. These findings can offer valuable practical insights for developing optimized electroplating formulations, particularly for TSV applications where controlled additive adsorption is critical for achieving superconformal filling of high-aspect-ratio features. The results emphasize the need for careful balancing of the acid composition, chloride content, and additive ratios in copper electrodeposition processes. The work establishes clear correlations between solution chemistry, molecular structure of additives, and their adsorption behavior on copper electrodes, contributing to better fundamental understanding and practical optimization of copper electroplating systems.

Keywords: copper, ellipsometry, organic additives, adsorption, polyethylene glycol, Janus Green B

Int. J. Corros. Scale Inhib., 2025, 14, no. 2, 894-904
doi: 10.17675/2305-6894-2025-14-2-24

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