Residual stress evolution during long-term and cyclic aging and annealing of gold films deposited by electron beam evaporation

• We study residual stress evolution of gold film by long-term aging and annealing.
• We observed reduction in size and amount of voids in gold film after annealing.
• Reduction of voids was correlated to the increase of residual stress.
• Residual stress decreased after natural placement under room temperature.
• Residual stress firstly increased and then become stable during thermal holding.

Long-term and cyclic aging and annealing were performed to the gold films deposited on silica substrate. Residual stress evolution of gold films during room-temperature natural placement (aging) and 50 °C–80 °C thermal holding (annealing) was studied. Various combinations of natural placement and thermal holding were adopted. Substrate curvature method using Stoney equation was applied to calculate the residual stress. Observation and comparison of the microstructures of gold films before and after thermal holding were made. Results show that residual stress decreased after natural placement due to stress relaxation caused by surface and grain boundary diffusion. For the treatment of thermal holding, the change of residual stress is a competition between stress generation caused by recovery and the stress relaxation caused by diffusion. Two experiments with different combinations of natural placement and thermal holding show similar result of residual stress variation.