Aspects of lateral resolution in energy-filtered core level photoelectron emissionmicroscopy

Abstract

Lateral resolution is a major issue in photoelectron emission microscopy (PEEM) andreceived much attention in the past; however a reliable practical methodology allowing forinter-laboratory comparisons is still lacking. In modern, energy-filtered instruments, corelevel or valence electrons give much lower signal levels than secondary electrons used in stillmost of the present experiments. A quantitative measurement of the practical resolutionobtained with core level electrons is needed. Here, we report on critical measurements ofthe practical lateral resolution measured for certified semiconducting test patternsusing core level photoelectrons imaged with synchrotron radiation and an x-rayPEEM instrument with an aberration-corrected energy filter. The resolution is250 ± 20 nm and the sensitivity, 38 nm. The different contributions to the effective lateral resolution(electron optics, sample surface imperfections, counting statistics) are presented andquantitatively discussed.