Growth morphology of electroplated copper: effect of seed material and current density

The growth of electroplated Cu films has been studied as a function of seed material and current density. Cu films were electroplated on a thin seed layer of Cu or W material using current densities of 0.10 and 0.16 A/cm². For W seed layers, Cu grains were nucleated irregularly with massive grain growth, and smaller grains coalesced into larger ones to further build up the electroplated Cu film. The Cu film growth morphology on the Cu seed layer was found to be different. Cu clusters were uniformly formed all over the Cu surfaces, which suggests the absence of preferential nucleation. Subsequent grain growth was similar to that on the W seed layer. The Cu grain growth showed strong dependency on the seed material grain size