Substrate Effect on Modulus of Elasticity and Hardness of Thin Film Under Nanoindentation Test

Abstract

Mechanical properties of thin film under nanoindentation test by Finite Element Analysis (FEA) have been studied in this literature. An axi-symmetric bi-layer model has been developed in commercial finite element analysis software, ABAQUS. Aluminum (Al) comprises the thin film whereas Silicon (Si) comprises the substrate. This model has been simulated using the loading condition that mimics real nanoindentation test, i.e. an indenter has been probed to a predefined depth onto Al-thin film. Modulus of elasticity and hardness of thin film have been calculated by existing empirical relationship. Substrate effect on determination of film modulus and hardness has been investigated by varying the substrate modulus. It has been observed that substrate effect is pronounced on film modulus determination whereas hardness is not significantly sensitive to this effect. Depth of indentation has also been varied over a long range to observe the indentation effect on these parameters. It is obvious that film modulus is increased with depth increment. However, hardness variation is not regular. Different friction condition is also in the scope of this study. It has been observed that friction does not affect modulus of elasticity. It, however, affects hardness of thin film. This is attributed to the dissipation of the energy needed to overcome friction at film-indenter interface.