An integrated sputter-ion pump add-on lens unit for scanning electron microscopes

Abstract

A sputter-ion pump integrated in an add-on objective lens unit has been developed. By integrating the sputter-ion pump into the add-on objective lens, the vacuum condition inside the add-on lens can be improved. Experiments indicate that a working pressure of between 1.0E-6~1.0E-7 Torr can be obtained, therefore reducing specimen surface contamination. The same permanent magnets are used to excite the magnetic field for both the lens and pump. The pumping speed and improvement in the vacuum level of the lens were estimated by the electrical current drawn by the ion pump. Images obtained with the integrated unit show an improved spatial resolution performance compared to conventional SEM imaging, demonstrating that it can function as a high resolution lens attachment.