Vertical distance from shading in the SEM

Vertical data collected by Scanning Electron Microscopy (SEM) are important for sample characterization, 3D reconstruction, and flex manipulation. Traditional methods are limited by the extent to which the probe obstructs the view of the sample along the vertical axis. Herein, we propose a novel SEM microprobe for measuring the vertical distance between the probe and substrate. To form a semi-transparent hole that is set as the objective regions in processing of the SEM images, an epoxy film was embedded in the through-hole at the tip of the microforce probe with 3D printing. The film can be modified with a focused ion beam (FIB) system. The motion of the modified probe along the vertical axis is controlled by a nanopositioner and the process is recorded by taking a real-time SEM video. The change in gray contrast caused by the semi-transparent epoxy is corrected during the SEM image processing of the video. By comparing the gray contrast with the nanopositioner motion data, we find that the change in gray contrast can provide feedback for adjusting the displacement between the probe and the substrate, and the resolution can be up to 100 nm. We propose a novel and simple method for measuring vertical distances in the SEM, which is useful for in-situ measurements and nanomanipulations.