Stress-induced Migration of Electroplated Copper Thin Film Interconnections Depending on Thermal History

Effect of the change of crystallinity and micro texture of electroplated copper thin films by annealing on the stressinduced migration was investigated experimentally and theoretically. The micro texture of electroplated copper thin films changed drastically as a function of their electroplating conditions and the annealing temperature after the electroplating. The crystallinity of the electroplated film was improved by annealing at 400C for 3 hours. However, stress-induced migration was activated even though interconnection was kept at room temperature without any application of electrical current after annealing. This is because high residual stress was caused by shrinkage of electroplated copper due to change of crystallinity. Molecular dynamics simulations showed that copper atoms diffused significantly around the grain boundaries in the annealed film in which high residual tensile stress existed. Keywords-component; Reliability, Electroplated copper thin film interconnection, Stress-induced migration