The synergistic effects of polymer additives such as gelatin and poly(ethylene glycol) (PEG) and Cl~- on Cu electrodeposition have been investigated by measuring the polarization curves for Cu deposition, by rotating ring-disk electrode technique and by AC impedance measurements. The cathode potential for Cu deposition was greatly polarized in solutions containing both Cl~- and gelatin or PEG, showing evident synergistic effect of polymer additives and Cl~-)on Cu deposition. The cathode potential was shifted to the less noble direction with increasing the concentration of Cl~- in solutions containing polymer additives and showed the maximum polarization at Cl~- concentration range between 0.1 and 1mmol/L. The rotating ring-disk electrode technique revealed that Cu deposition in solutions containing small amounts of Cl~- proceeded with initial formation of adsorbed intermediate CuCl_(ad). The Cole-Cole plots obtained by AC impedance techniques suggest that the reduction of CuCl_(ad) is suppressed by polymer additives. The morphology of Cu deposited from solutions containing both PEG and Cl~- showed the compacted surface composed of smaller grains due to an increase in the overpotential for Cu deposition.
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