In this study, the effect of plating current densities on self-annealing behaviors of electroplated Cu films was found to be relevant to the polarization resistance of electroplating systems. Porous films with defects occurred at low plating current density or at low polarization resistance. In contrast, dense films with small grains occurred at higher plating current density or at higher polarization resistance. However, when more current was further supplied, Cu aggregation occurred and deposited films became spongy or dendritic. We suggest that both the defects within porous films and the underlying energy of fine-grained deposits accelerated self-annealing. These two characteristics competed with each other to determine the resistivity drop by self-annealing. On the other hand, the (111) texture evolutions of deposited Cu films with an increase of plating current densities were consistent with the evolutions of resistivity and surface morphology.