Stress relaxation in AlCu thin films

The activation energy residual stress relaxation in Al2wt.%Cu thin films on silicon was determined to be 0.87 eV by measuring the stress as a function of time in the temperature range 373–523 K. This value is approximately that for grain boundary diffusion. The stress in the films at the relaxation temperatures is shown to be compressive and in excess of the yield strength for the highest relaxation temperatures. Dislocation processes are therefore thought to contribute to the relaxation above 448 K.