Quantitative Study of Nanoscale Contact and Pre-Contact Mechanics Using Force Modulation

摘要

For submicron-scale mechanical property measurements, depth sensing nanoindentation techniques are very successful and gaining much attention. However, for ultra-small volumes of materials below a length scale of 10 nm, measuring the quantitative mechanical properties of materials is still a problem. The atomic force microscope (AFM) has very good surface sensitivity and has been shown to measure nanomechanical properties. However cantilever instability, conventional force detection and displacement sensing make contact area measurement difficult, hence the measured mechanical properties are usually only qualitative. In this article, we show that combining force modulation with depth sensing nanoindentation allows measurement of the mechanical properties of materials on the nanometer scale. With this technique we have studied the role of oxide layers on the mechanical response of Si surfaces. We also present a novel quantitative stiffness imaging technique, which can be used to directly map the mechanical properties of materials with submicron lateral resolution.