Role of SPS in chloride ions and PEG additive system for copper electrocrystallisation

Cyclic voltammetry and chronoamperometry techniques were employed in the study of copper electrocrystallisation process on a glassy carbon electrode from acid sulphate electrolytes in the presence of bis(sodiumsulfopropyl) (SPS) and polyethylene glycol and Cl– ions (PEG–Cl––SPS). The role of SPS in the effect of PEG–Cl––SPS was investigated. It was found that SPS can weaken the strong suppression of PEG–Cl– for copper electrocrystallisation. This weakening was proportional to the SPS concentration. The increase in SPS concentration also resulted in the promotion of the nuclei number density. The nucleation mechanism depended on not only SPS concentration but also the potential applied in the presence of PEG–Cl––SPS. In the presence of PEG–Cl––SPS, instantaneous nucleation followed by three-dimensional growth (3DI) occurred at negative electrodeposition potentials, as in an additive free bath. However, progressive nucleation followed by three-dimensional growth (3DP) was found at less negative potentials.