Numerical modeling of strain hardening effect on an AFM cantilever undergoing stress in tapping mode

Abstract

AbstractTapping mode is one of the scanning modes possible when using an AFM. In tapping mode, the cantilever is driven to oscillate up and down at or near its resonance frequency. Nano‐measurement researchers and metrologists have been concerned with errors in feature dimensions arising from bad cantilever as a result of strain hardening. Strain hardening is when a metal is strained beyond the yield point. This work involves modeling an AFM cantilever with a point load at the tip undergoing transverse vibration. The numerical work involves mapping out the stress field and identifying areas susceptible to plastic flow to advise equipment makers on how to design against strain hardening. The numerical analysis was carried out using COMSOL Multiphysics 5.0. Different dimensions of the cantilever (length = 100‐500 µm and width = 20‐50 µm) and Eigen frequencies were varied to investigate the optimal dimensions for designing an AFM cantilever against strain hardening. The numerical simulation shows that the AFM cantilever experiences increased deformation and strain hardening between a range of length 400‐500 µm and 200‐300 µm with the highest at 100‐200 µm and width of 20‐40 µm. It is also observed that the effect of strain hardening on the cantilever is minimal at lengths 300‐400 µm and widths 40‐45 µm when undergoing tapping mode with the highest Eigen frequencies.