Plastic and elastic behavior of sputtered bilayered films by nanoindedtation

Deformation behavior of sputtered Al/TiN and Cu/TiN bilayered films was examined by using dissipated and elastic energies estimated from the area enclosed by the load-displacement curve of nanoindentation. These films studied consisted of TiN top-layer of 500 nm and Al or Cu underlayer of 0 - 500 nm on glass or sapphire substrate. The dissipated energy for plastic deformation increased with increasing thickness of metal underlayer, while the elastic energy remained constant. A decrease in plastic energy was observed by changing the underlayer material from Al to Cu. Further, a reduction in elastic energy was observed when a sapphire was used as a substrate. Experimental results show that the plastic deformation mainly occurred in metal underlayer and the elastic deformation did in TiN layer and in the substrate. It was concluded that the yield stress and elastic modulus of layers and substrate strongly affect the deformation behavior of the films.