The nucleation and growth of constant-potential electrochemically deposited copper was investigated using NH3 copper complexed alkaline baths. The mechanisms of copper nucleation and growth were studied under four conditions: (1) on nonpatterned physical vapor deposited (PVD) TiN, (2) on inlaid (Damascene) PVD TiN trenches, (3) on nonpatterned PVD Cu, and (4) on inlaid PVD Cu trenches. Growth of copper was conformal at lower overpotentials and became subconformal at higher overpotentials, indicating mass-transfer restricted growth in the trenches. On TiN there was a potential-dependent incubation period, which is believed to be due to the multistep electrochemical reduction occurring in this system. The high surface energy between the deposited copper and the TiN resulted in spherical growth morphology, which can be classified as following the Volmer-Weber nucleation and growth mechanism. Complete filling of trenches with copper was achieved, but with sporadic pinhole voids.