Optimization of the Electron Optical System of a Scanning Electron Microscope for Measuring the Size of Micro- and Nanoobjects

Abstract

A computer simulation of the electron-optical system of a low-voltage scanning electron microscope is carried out. The finite element method is used to calculate the electromagnetic fields of the system. It is established that the system with intermediate electron acceleration inside the column is the most suitable for the low-voltage mode. It is shown that the best combination of resolution and performance can be obtained when the 3rd condenser—objective lens system is operating close to the telecentric mode. At the same time, compared with the telecentric mode, the measurement performance can be increased by 35% at the lowest achievable resolution. Compared with traditional SEM (scanning electron microscope) configurations, the proposed solution provides an increase in performance of more than 100 times while maintaining the specified accuracy of measuring the size of structures with a minimal size of up to 65 nm.