Elastic modulus of TiHfCN thin films by instrumented indentation
Résumé
The determination of the elastic modulus of thin films by indentation at nano or micrometric scale is possible by applying different models allowing the separation of the substrate influence from the indentation measurement. However, for an accurate determination of the elastic modulus, the indentation depth and/or the contact area must be corrected by taking into consideration the frame compliance of the instrument and the blunted tip effect of the indenter. In nanoindentation, these two corrections are performed prior to the indentation experiments. However, in microindentation, some works showed that the compliance term does not have a constant value. As a result, a more consistent modeling must necessarily consider this compliance term as an unfixed parameter, at least for this range of loading. In addition, a discussion about the calculation of the contact area according to the methodologies of Oliver and Pharr (1992) [13] and of Hochstetter et al. (1999) [14] is also proposed to consider the sinking-in or piling-up effects, respectively, which can take place during the indentation process, depending on the mechanical behavior of the material. Finally, different weight functions and the model of Tricoteaux et al. (2010) [12] are applied to the raw and corrected data. This methodology is applied in microindentation and validated by nanoindentation for the determination of the elastic modulus of a TiHfCN thin film. A convergence of the results is observed only if the two corrections are taken into account. Accordingly, the elastic modulus of the TiHfCN film is found to be close to ~ 500 GPa.