Application of nano-tips to cold field emission CD-SEM

Abstract

Experimental nano-tips have shown significant improvements in the resolution performance of a cold field emission CD-SEM. Nano-tip electron sources are very sharp electron emitter tips and offer higher brightness and smaller electron source size. An electron microscope equipped with nano-tip electron gun can provide images with higher spatial resolution and with better signal-to-noise ratio. The images taken with experimental nano-tips showed a minimum two-fold improvement in resolution performance than the specification of the test SEM. The lifetime and stability of the nano-tip electron gun was good, the tip stayed useful for high-resolution imaging during many days of tests without flashing. The tip lifetime was found to be over a year. Through this study the most important questions and problems associated with nano-tips and their possible applications to SEMs were investigated. These were related to the tip making procedures, the theoretical assessment of the Hitachi S-6000 critical dimension SEM's electron gun and to the preparation of the SEM for insertion of nano-tips, and finally to the experiments with nano-tips. Based on the results it appears feasible that nano-tip gun technology could replace the standard electron source and thus provide increased instrument performance. The result of this work clearly demonstrated that useful resolution improvement can actually be achieved in practice. The lifetime and resolution of the nano-tip gun were surprisingly good, which opens the possibility for the development of a new higher-resolution electron gun technology.