Growth kinetics and microstructures of Cu nanofilms on mo substrate by electrodeposition

Copper (Cu) nanofilms have been prepared on a molybdenum (Mo) substrate by the electrodeposition method from the electrolyte solutions of copper sulfate (CuSO₄) and trisodium citrate (C⁶H₅Na₃O₇) added by surfactant PEG-6000. The growth kinetics and microstructures of films were investigated by cyclic voltammetry (CV), chronoamperometry (CA), scanning electron microscopy (SEM) and atomic force microscopy (AFM). Cyclic voltammetry and chronoamperometry clearly show that the electrodeposition is controlled by the diffusion process of copper ions. By means of Scharifker-Hills model, the Cu nucleation mechanism in 0.1mol/l CuSO₄ and 0.2 mol/l C₆H₅Na₃O₇ solution is revealed to be an instantaneous nucleation. Potential, solution concentration and organic additive have an influence on the microstructure of copper film. SEM and AFM results show a uniform copper layer with 7.7 nm roughness can be fabricated when deposition charge quantity is 0.7 C/cm² at-0.7 V vs SCE.