The influence of mass transport on the deposit morphology and the current efficiency in pulse plating of copper

Abstract

The morphology of copper deposits formed by pulse plating from an acid sulphate electrolyte is investigated. The steady and non-steady state conditions of mass transport are controlled by use of a rotating hemispherical electrode. Below the limiting pulse current density (ipl), granular deposits are observed. Aboveipl, regardless of the individual values of the pulse parameters, dendritic deposits are formed. Measured current efficiencies are compared with a theoretical model, which predicts a rapid decrease of the efficiency with the increasing ofip/ipl forip/ipl greater than one, whereip is the applied pulse current density. For a given set of pulse parameters, the measured current efficiency increases with the deposit thickness due to the increase of the effective surface area. This effect is particularly important for dendritic deposits.