Electrodeposited Cu Film Morphology on Thin PVD Cu Seed Layers

Abstract

The electrodeposited Cu film morphology on thin physical vapor deposited (PVD) Cu seed for various conditions and correlation with Cu fill of dual Damascene structures is discussed. Thinner PVD Cu seed on Ta yields isolated electrodeposited Cu particles, while smooth plated films are obtained for thicker seed. Changes in suppressor additive and virgin makeup solution (VMS) concentrations have a limited impact on the morphology of Cu electrodeposited on thin Cu seed. Increased seed to plate queue time appears to lead to coarser, more isolated deposited Cu particles. Changes in Cu fill performance of dual Damascene structures having a 28 nm critical dimension (CD) were consistent with blanket wafer results for seed to plate queue times, but less so for changes in suppressor and VMS. A chemical vapor deposited (CVD) Co liner appears to improve the effective thickness of PVD Cu seed and hence the electrodeposited Cu film morphology for conditions considered in this study.