Design and aberration study of a new miniature energy analyzer with correctors in a scanning electron microscope

Abstract

The authors design a new miniature energy analyzer with a magnetic sector and corrector systems that can be installed in a scanning electron microscope for measurement of electron energy loss spectra. In order to correct the geometrical aberration caused by a magnetic sector field, two new corrector systems are designed using ray tracing simulations. One corrector system, using a simple structure, fully corrects second-order aberration and partially corrects third-order aberration. Another corrector system fully corrects third-order aberration in the x-direction. By aberration correction, energy resolution of similar to 10 meV at an initial angle of 5 mrad can be achieved with either of the two corrector systems. Additionally, we reveal an overall process of aberration correction in ray tracing simulations, which can be a useful guideline for aberration correction. Notably, we have established a new method of aberration correction using a simple matrix equation. Using this method, second-order aberration can be fully corrected both conveniently and rapidly. This study enables us to easily calculate and correct geometrical aberration without solving complicated equations.