Morphology Control of Copper Growth on TiN and TaN Diffusion Barriers in Seedless Copper Electrodeposition

Abstract

Growth behavior of copper on and diffusion barriers according to the compositional change of copper-citrate complex baths was studied in seedless copper electrochemical deposition. The peak potentials of cyclic voltammograms in the forward potential sweep were dependent on the concentration ratio of and in the baths. For the bath of , when one-step deposition of copper was performed at a peak potential for competitive reduction of both and ions, the 3D island growth of copper including lamella-like structure was shown. A peak for reduction and a peak for reduction existed separately for the bath of . Two-step deposition of copper in this bath gave birth to the 3D island plus layer-by-layer growth of copper. Interfacial adhesion between copper and was measured as 12 and , respectively, for both deposition conditions. The electrical resistivity of copper films grown by two-step deposition was lower than that by one-step deposition for the same thickness.