TEM Sample Preparation by Single-Sided Low-Energy Ion Beam Etching

Conventional FIB ex-situ lift-out is the most common technique for TEM sample preparation. However, the scaling of semiconductor device structures poses great challenge to the method since the critical dimension of device becomes smaller than normal TEM sample thickness. In this paper, a technique combining 30 keV FIB milling and 3 keV ion beam etching is introduced to prepare the TEM specimen. It can be used by existing FIBs that are not equipped with low-energy ion beam. By this method, the overlapping pattern can be eliminated while maintaining good image quality.