Dynamic Probe Calibration for Quantitative Measurements with Atomic Force Microscopy

Abstract

Atomic Force Microscopy (AFM) quantitative measurements are based on optimal instrumentation and control design, as well as diagnostics, calibration of AFM probes, and extraction of sample material properties from experimental data. In this paper three interrelated topics are discussed. (a) We analyze probe thermal noise to extract AFM probe dynamic parameters (resonant frequency, Q-factor, spring constant), verify instrumental capabilities for multi-frequency measurements, and obtain optical beam deflection sensitivity and noise level. This analysis is performed on experimental data acquired by Dynamic Cantilever Calibrator (DCC), designed to boost a performance of AFM electronic controllers. (b) We characterize tip shape and tip-sample force interaction with parametric models and apply them for evaluation of the probe geometry and shapes of the tips. These are important factors for quantitative AFM studies of local electrical and mechanical properties. (c) We analyze the accuracy of elastic modulus calculations by AFM nanoindentation based on error propagation that leads to practical recommendations on choice of the probe's spring constant for quantitative measurements.