AVS 46th International Symposium
    Thin Films Division Monday Sessions
       Session TF+VM-MoM

Paper TF+VM-MoM5
Elastic and Plastic Behaviors of Al/TiN Multilayered Thin Films Evaluated by Nanoindentation

Monday, October 25, 1999, 9:40 am, Room 620

Session: Advances in Hard and Superhard Coatings I
Presenter: E. Kusano, Kanazawa Institute of Technology, Japan
Authors: E. Kusano, Kanazawa Institute of Technology, Japan
Y. Sawahira, Kanazawa Institute of Technology, Japan
N. Kikuchi, Kanazawa Institute of Technology, Japan
H. Nanto, Kanazawa Institute of Technology, Japan
A. Kinbara, Kanazawa Institute of Technology, Japan
Correspondent: Click to Email
Elastic and plastic behaviors of multilayer films of Al (Young's modulus:70GPa) and TiN(Young's modulus:350-400GPa) have been investigated for various layer numbers with different total Al thicknesses in order to reveal the role of hard TiN and soft Al layers on nanomechanical properties in multilayered films. Both Al and TiN layers were deposited by dc magnetron sputtering. Aluminosilicate glass was used as substrate. The number of layers prepared was 4, 20, and 40 for the total Al thickness of 100-500nm. The total thickness of TiN layers was kept at 500nm, including the top layer of 250nm. The microhardness and Young's modulus of the films were evaluated by nanoindentation. The energies consumed for elastic and plastic deformations were calculated from the load-displacement curve obtained by the indentation. The microhardness decreased with increasing the total Al thickness. The hardness enhancement by the multilayer structure was observed for 20- and 40-layer films with Al layer thicknesses of 10 or 5nm (the total thickness of 100nm) and TiN layer thicknesses of 26 and 13nm. The energy dissipated during the indentation also increased with the total Al thickness. The dissipated energy for films with 40 layers of Al/TiN was smaller than that for the films with 4 or 20 layers of Al/TiN for all Al thicknesses. In contrary, the elastic energy was independent both of the total Al thickness and of layer numbers. As a result, the ratio of dissipated energy to the loaded energy during the load/unload of the indentation yielded a minimum at an Al thickness of 100nm for 40-layer films. The ratio at the minimum was about 20% smaller than that of the monolithic TiN film. This means that the 40-layer film with a total Al thickness of 100nm is more elastic than the monolithic TiN. It is concluded that the enhancement in the film microhardness for multilayered films with thin Al layers is related to the decrease in the dissipated energy.