Modeling of stress evolution of electroplated Cu films during self-annealing

Abstract

Electroplated Cu films are known to change their microstructure at room temperature due to the self-annealing effect. This recrystallization process results in a film-thickness-dependent stress evolution. Films with the thickness of 5μm and below decrease in stress with time, while thicker films reveal initially an increase in film stress followed by a stress relaxation at a later stage. This behavior is explained by the superposition of grain growth and grain size dependent yielding. Existing models have been used and improved to describe the mechanisms related to stress evolution. In general, the models proposed in this study provide a satisfactory description of the stress evolution of electroplated Cu films and the simulated results show good agreement with the experimental data. This gives the possibility to evaluate and predict mechanical behavior of electroplated Cu films at room temperature.