New insight into pile-up in thin film indentation

Abstract

This work builds involves leveraging our recent thin film mechanics model on the discontinuous transfer of strain from the film to the substrate. In applying this model with well-defined film and substrate properties we were able to decouple the effects of elastic modulus and Poisson's ratio mismatch in the indentation process. In doing so we identified new insight in the processes of pile-up and strong evidence suggested a dependence on film thickness and ratios of film/substrate of elastic modulus and Poisson's ratio. Atomic force microscopy was employed to characterize the degree of pile-up and correlate it with the above dependencies. We believe these efforts will enable the prediction of the degree of pile-up and subsequently the removal of its influence in measuring thin film behavior. © The Society for Experimental Mechanics, Inc. 2014.