Experimental and theoretical investigation of L-cysteine influence over the electrodeposition mechanism for a novel sustainable acid copper electroplating formulation

• A novel sustainable acid copper electroplating formulation capable of obtaining deposits with low roughness and small grains was proposed. • L-cysteine was employed as the only additive. • The physics behind the L-cysteine mechanism of action was discussed from multiple point of views. Despite being widespread all over the manufacturing world, industrial acid copper electroplating exploits the same classes of additives since the second half of the 20th century. This work aims to overtake the classical set of accelerators, suppressors, levelers and inorganic salts (e.g. sodium chloride) with low-cost and sustainable additives that can solve multiple roles. A multidisciplinary approach based on spectroscopy, diffractometry, electrochemistry and computational chemistry is employed to characterize the effects of L-Cysteine and its action mechanism during the electrodeposition. We demonstrate how and why this amino acid can promote both grain refinement and roughness reduction without any other additive or inorganic salt. This result is achieved by considering and analyzing the findings of multiple experimental techniques and comparing them with computational calculations and simulations. Such an approach can open new pathways for designing industrial electroplating procedures, ensuring sustainability.