Stress evolution during annealing of Cu/Au, Cu/Ag and Au/Ag bilayers.
Experimental observations of the measurements of the average force F per width (i.e., F/w) during annealing of Au/Cu, Cu/Au, Ag/Cu, Cu/Ag, Au/Ag and Ag/Au bilayers attached to silicon substrate are reported. Systems with total thickness of 12 nm and thicknesses of films of 6 nm are investigated. The total force per width in a system was determined in-situ by the substrate curvature measurement method with the laser scanning technique during deposition and annealing. Significant stress evolution during the first cycle of heating was observed for all samples. It was found that during the first annealing cycle, irreversible changes occur in layers and increases the interface roughness. An increase in the interface roughness modifies the coefficients of elastic deformation of layers. Subsequent annealing cycles do not cause major changes in the stress in a bilayer.