Atomic force microscopy (AFM) tip metrology and inspection by knife edge diffractometry

This study presents a novel method for Atomic Force Microscopy (AFM) tip feature characterization, integrating with knife-edge interferometry-based experiments and Rayleigh-Sommerfeld diffraction theory-based mathematical modeling. The proposed approach provides a non-destructive and efficient method to monitor AFM tip wear by relating the measured fringe features to changes in radius and roughness. To generate controlled tip wear, a two-stage etching process was conducted, revealing notable changes in fringe patterns that correspond to an increased wear extent. Fringe pattern characteristics, such as the spacing between fringe orders and the entropy of vertical components, exhibited systematic changes as tip sharpness decreased. Quantitative analysis using structural similarity index measure, similarity index, and mean squared error further provided quantitative indicators of the tip geometric and roughness conditions. The results were validated by Scanning Electron Microscopy and corresponding AFM imaging. The successful implementation of the proposed method provides a non-destructive and efficient way to monitor tip wear by relating measured fringe features to simulated patterns, yielding a rapid quantitative wearing extent evaluation.