Mechanical spectroscopy and structural evolution of CuMo thin films

CuMo thin films with a typical thickness of 200 nm have been prepared by Ion Beam Sputtering (IBS) on oxidised silicon (100) substrates. Two samples with symmetric (atomic) composition Cu30Mo70 and Cu70Mo30 where studied. `Directʹ observations of the microstructure were performed by X-ray diffraction. The samples have been characterised in their assputtered state, then after annealing at increasing temperature. On the other hand, a vibrating reed device specially adapted for thin adherent films has been used to determine the mechanical properties over a temperature range between 20°C and 500°C. In this paper, it is shown that the structural evolution in temperature highly depends on the sample composition. Particularly, in the Mo-rich specimen, two independent stages have been shown. Indeed, the segregation process is preceded by a structural relaxation phenomenon. We have also shown that internal friction experiments are quite useful in the study of these structural modifications occurring in thin films.