Seed layer dependence of room-temperature recrystallization in electroplated copper films

Room-temperature recrystallization (self-annealing) of electroplated copper (Cu) films is investigated using three kinds of seed/barrier layers with nontexture and (111) texture. The as-plated films have almost the same texture as the seeds. The texture changes during self-annealing depend on the seed texture. The (111) texture of the self-annealing films increases for the film deposited on the nontexture seed layer, but decreases for the film deposited on (111) texture seed layers. For all the plated films, tensile stress increases after self-annealing, which corresponds to the film shrinkage. Recrystallization rate of the Cu film plated on the nontexture seed layer is higher than the one on the (111) texture seed. It is postulated that the reduction of grain boundary energy is the major driving force for film self-annealing and grain growth.