Parametrization of atomic force microscopy tip shape models for quantitative nanomechanical measurements

Abstract

The uncertainty of the shape of the tip is a significant source of error in atomic force microscopy (AFM) based quantitative nanomechanical measurements. Using transmission electron microscopy, scanning electron microscopy, or tip reconstruction images, it is possible to parametrize the models of real AFM tips, which can be used in quantitative nanomechanical measurements. These measurements use algorithms described in this article that extend classical elastic, plastic, and adhesive models of contact mechanics. Algorithms are applicable to the tips of arbitrary axisymmetric shapes. Several models of AFM tip have been utilized. The goal of tip model parameterization is to develop AFM tip-independent quantitative mechanical measurements at the nanometer scale. Experimental results demonstrate independence of the AFM measurements from tips and their closeness to bulk measurements where available. In this article the authors show the correspondence between microtensile, nanoindentation, and AFM based indentation for measuring the modulus of a spin on low-k dielectric polymer thin film. These results provide a confidence that with the described procedures AFM can be used for reliable quantitative nanomechanical measurements.