Recrystallization-induced void migration in electroplated Cu films

During the annealing of electroplated Cu at 300–400 °C, voids nucleated at the film/substrate interface and migrated toward the film-free surface as the recrystallization proceeded. Voids were located at the recrystallized/unrecrystallized (R/UR) interface and served as markers of the interface motion. Kinetics of the R/UR interface migration showed t12 dependence, suggesting that the recrystallization of the electroplated Cu was controlled by the long-range diffusion of atoms through high-diffusivity paths, such as grain boundaries and dislocation cores.