The electromigration lifetime in multilevel Cu damascene interconnects has been investigated. The Cu lifetime was strongly influenced by the diffusion barrier liner at the cathode end of the line. This partial blocking boundary at the Cu via/Cu line interface can drastically change the Cu lifetime. A triple-log-normal function was used to analyze the failure distribution in a dual-damascene interconnect. The failure mechanism in the Cu line/Cu via dual-damascene line with thin liner at the interface was similar to the result obtained when testing a single stripe with large reservoirs. The electromigration activation energies for unpassivated Cu lines tested in nitrogen and forming gas (N-2 +5% H-2) were found to be 0.7 and 0.9 +/- 0.1 eV, respectively.