Effect of stresses on the evolution of annealing textures in Cu and Al interconnects

A new model is advanced to account for the evolution of annealing textures in copper and aluminum interconnects based on strain and surface energies. The interconnects, whether they are conventionally or damascene-process fabricated, are subjected to stresses during room temperature or elevated temperature annealing, which, in turn, gives rise to strain energies. The strain energy of a deposit is influenced by its texture and geometry. The annealing texture of an interconnect line is determined such that its elastic strain and surface energies are minimal. The measured textures in damascene-processed copper interconnects and a published result of conventionally processed Al-1%Cu interconnects are discussed based on minimization of their strain and surface energies.