Recovery of elastic constant of ultrathin Cu films by low temperature annealing

Abstract

Annealing effect on the elastic constant of Cu thin films was investigated by acoustic-phonon resonance spectroscopy. Annealing treatment was performed after the deposition in vacuum condition for 30min at various temperatures up to 200°C. It did not cause obvious changes in the x-ray diffraction spectra, but it significantly increased the elastic constant. The elastic constant of the as-deposited Cu film was smaller than that of bulk Cu by 20%, and it recovered to the bulk value by the postannealing at 200°C.