Atom motion of Cu and Co in Cu damascene lines with a CoWP cap

The electromigration in Cu bamboo-like grain structure lines with CoWP capping layer and the effect of Cu conductivity from diffusion of Co into Cu, were studied. Focused ion beam and scanning transmission electron microscopy were used to examine the Cu line microstructure and void formation. The Cu line was completely encased in metallic thin film layers, and the map was obtained by acquiring energy dispersive x-ray spectra. The extracted activation energies for Cu electromigration and Co diffusion in these samples were found to be comparable with bulk-like diffusion.