Calibrating the Stiffness of Afm Cantilevers via Instrumented Indentation Devices

Abstract

In recent years the study of mechanical properties using atomic force microscopy (AFM) has become very popular. As it uses much lower forces than nanoindentation methods it allows to focus on smaller volumes which makes it an excellent tool for the study of thin films and the creation of high-resolution maps. Although it gives a quantitative as well as a qualitative analysis some open problems remain in the quantitative aspects. One of the problems encountered is related to the stiffness of the AFM cantilever. Most microscopes offer builtin methods for the calibration of cantilever stiffness. Unfortunately, these are often insufficient from the point of view of metrology. Uncertainties and traceability are rarely discussed.Alternatively, the stiffness of a cantilever can be determined using a nanoindentation device. This well-known method offers simpler uncertainty analysis and traceability. In this contribution we explore the possibilities of this method from the metrological point of view. We shall present an uncertainty budget with focus on repeatability and we shall also discuss traceability issues.