Finite-element modeling of nanoindentation for evaluating mechanical properties of MEMS materials

We have developed procedures based on finite-element modeling of nanoindentation data to extract mechanical properties from thin, hard films and ion-beam-modified layers on softer substrates. The method accurately deduces the yield stress, Young's modulus, and hardness from indentations as deep as 50% of the layer thickness. We use these procedures to evaluate two hard layers potentially useful for reducing friction and wear of components in micro-electromechanical systems (MEMS): Ni implanted with Ti and C, and diamond-like carbon layers. We show that the modeling works well even for materials whose hardness approaches that of diamond, a case where commonly used analytical methods for deducing the modulus fail.