Atomic force microscopy nano-indentation for testing mechanical properties in thin films

Abstract

We study the mechanical properties of Cu thin films on Si (100) by performing nano-indentation using an atomic force microscopy. Cu films with thickness of 0.3 μm, 1 μm and 2 μm were analyzed. Area profile studies let us understand the critical influence of the indenter geometry uncertainty on the estimation of the mechanical properties. This seems to be very important when studying thin films because penetrations depths are very small and close to the indenter apex which could have geometrical discontinuities. We found that the hardness of the samples and Young modulus decreases as the film thickness increases. The origin of this behavior could be ascribed to a substrate-film mechanical coupling or a microstructural effect.