Effect of HEDP on copper electroplating from non-cyanide alkaline baths

Abstract

Effects of the different concentrations of 1-Hydroxyethylidene-1,1-diphosphonic acid (HEDP) on copper electroplating from non-cyanide baths with two complexing agents were investigated by different electrochemical methods. Cyclic voltammetry and current transient measurements were used to characterise the copper electroplating system in order to analyse the nucleation and growth mechanism. The quartz crystal microbalance and chronoamperometric methods were used to study the relationship between the mass change and the deposition time. The current efficiency of electrolytes without HEDP was 95·39%. However, when the HEDP concentration was 40, 60 and 80 g L−1, the current efficiency was 93·76, 92·87 and 94·93% respectively. The structure and surface morphology of Cu films were analysed by X-ray diffraction and scanning electron microscopy (SEM). The morphology of copper films obtained with 40 g L−1 HEDP presented a smooth and compact deposit, and the size of crystal particle was uniform.