Advances in scanning electron microscopy

This chapter discusses the advances in scanning electron microscopy (SEM). Alternatives to the previously characterized main body, physical part, or column of the SEM have progressively been introduced, including (1) scanning columns for electron spectrometers, such as those suitable to be inserted inside a cylindrical mirror energy analyzer, (2) testers and lithographs for semiconductor technology, and (3) miniaturized versions. The issues regarding further development of the classical general-purpose SEM are discussed in the chapter. Computer-aided design methods for calculation of electrostatic and magnetic elements and simulation of electron trajectories have enabled significant progress in tailoring the column design to prescribed electron optical parameters. Complete computer control of the device opens approaches to full utilization and easy adjustment of all possible operation modes. These two aspects are most important with regard to the recent development outlined in the chapter, and some new ideas have proved viable, particularly that of variable beam energy along the column. In SEM, new technologies—such as rare-earth based permanent magnets and particularly the family of various micro- and nanotechnologies that have projected themselves into the SEM instrumentation—are used.