Effects of Anode Design and Configuration on the Growth Dynamics and Surface Morphologies of Electrodeposited Copper Films

Abstract

The influence of different anode configurations on the growth mechanisms, transient currentsand surface morphologies of copper film using localized electrodeposition technique have been studied. Measured transient currents during electrodeposition wereused to investigate the underlying growth dynamics. SEM images were obtained and the surface morphologies of the deposited copper films were analyzed. It was found that the transient current increased when copper ions were able to grow directly on the empty surface of the copper film that was located away from the mini electrodes. This caused the copper ions to be deposited sporadically via the instantaneous growth mechanism and formed cluster of atoms on the empty surface of the copper film which led to rougher surfaces. In contrast, progressive growth was observed to occur at a faster rate for thedeposition performed using insulated mini electrodes, especially in the case of collinear double insulated mini electrodes as indicated by the reduction of the transient current with time. Besides, copper films with uniform and smoother surfaces were obtained when the depositions were performed using multiple or a large number of closely spaced mini electrodes. This was due to the fact that large number of closely spaced mini electrodes produced parallel and uniform electric field patterns.