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Tantalum (Ta) thin film was deposited onto Si (100) substrates using direct-current magnetron sputtering. The structure and mechanical properties of Ta films were investigated by X-ray diffraction, Field emission scanning electron microscope, and nanoindenter. The results indicated a transition from regular to irregular Hall-Petch relationship with decreasing grain size. Besides, a peak indentation hardness value of 12.8 GPa, much higher than that of bulk coarse-grained Ta, was obtained at the grain size of 36.3 nm.

An investigation on Cu/Cr/Si composite thin films demonstrated that a thin Cr layer affects the microstructures and mechanical behavior of Cu films significantly. The fracture modes changes from brittle fracture to ductile rupture, as indicated by the dimpled rupture of Cu films. Moreover, the Cr sticking layer can result in carrot-shaped rods and a fine grain size. Further analysis indicates their deformation and fracture processes are closely related to the coupling of dislocation-mediated plasticity as well as the formation and growth of voids which act as sites for nucleation of the dimples.

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