Characterisation and modelling of the nanoindentation experiment in Au layers

The nanoindentation experiment is an established technique for the determination of Hardness and Young's modulus of thin films. This standard data set is not sufficient to he used as input to finite element simulations, because elastic-plastic material data is being required for analysis of reliability of metal layers. Therefore stress-strain Curves are being determined by fitting the force displacement curves of the experiment with a finite-element model. Additionally this approach enables a solution for the so called substrate effect , because the stiffness of the Substrate can be considered in the fitting model. This known approach is being applied and tested on thin (< 500 nm) gold layers deposited on silicon. It is shown that even for indents that exceed 10 % of the film thickness a good sensitivity for Young's Modulus can be reached, but for the plastic data the results are not unique and a range of plastic properties can be fitted. It is shown, that this problem of the method can be solved by correlation of the indent profiles.