Extension of gravity center method for diameter calibration of polystyrene standard particles with a metrological AFM

In the particle diameter calibration using metrological AFM, the distance between center points of neighboring two particles is referred to as "lateral diameter" when a single-layer close-packed structure of particles is successfully formed. The distance between an apex of a particle and a substrate is referred to as "vertical diameter." In the previous studies, lateral diameter was calculated by manually selecting and extracting a line profile from metrological AFM data and directly applying a method to calculate a pitch of one-dimensional grating. As the manual line profile extraction depends on who does it, however, there is a possibility that calculated lateral diameter is varied from person to person. We developed a technology to calibrate diameter of polystyrene latex (PSL) particles by using our metrological AFM. In this study, the gravity center method is extended to three dimensions to calculate position of and the center of gravity in each particle. Lateral diameter, which was defined as distance between gravity centers of neighboring two particles, is calibrated and uncertainty in the lateral diameter calibration is evaluated. Deformation of particles was also estimated by using Young's modulus of thin film PSL and bulk PSL.