An analysis of copper film mechanical properties by means of nanoindentation technique

Nanoindentation is a technique commonly used for measuring the mechanical properties of the bulk materials. In this work, evaluation of the mechanical properties of a copper film is the interest. However, in order to perform the tests on the copper film, fused silica is used as substrate to constrain the film (as the mechanical properties are well-known). Instrumented nanoindentation tests are performed with a sharp indenter. From the unloading curve of the measured indentation load-displacement data, the elasticity of the film can be obtained by considering the contact stiffness. The main difficulty with the characterization of the films using instrumented indentation tests is to determine the separate contribution of the substrate and the film to the measured properties. In this work, the substrate effect is taken into consideration, its contribution on the elastic modulus is discussed. The comparison between evaluated elastic modulus and value from literature shows a good agreement. Finally, hardness of the copper film is evaluated considering the influence of the fused silica substrate.