Multibeam scanning electron microscope: Experimental results

Abstract

The authors present the first results obtained with their multibeam scanning electron microscope. For the first time, they were able to image 196 (array of 14×14) focused beams of a multielectron beam source on a specimen using single beam scanning electron microscope (SEM) optics. The system consists of an FEI Novanano 200 SEM optics column equipped with a multielectron beam source module. The source module consists of the multibeam source and an accelerator lens. In the multibeam source, the wide angle beam of a high brightness Schottky source is divided into 196 beamlets and focused by an aperture lens array. The accelerator lens is positioned on the image plane of the multibeam source to direct the beams toward the SEM column. The array of source images is further imaged by the SEM magnetic lenses, and the beam opening angle is defined at the variable aperture of the SEM. The system is designed to deliver 14×14 arrays of beamlets with a minimum probe size of 1 nm. In this article, the performance of the system is examined for a fixed magnification case.