Broad ion beam milling of focused ion beam prepared transmission electron microscopy cross-section specimens for high resolution electron microscopy using silicon support membranes

摘要

The use of focused ion beam systems is becoming routine for the preparation of site specific TEM cross-section specimens which are typically 50 -100 nm thick. Generally, the cross-sections are milled using a 30 keV ion beam, which unfortunately, can result in large amounts of damage to the sidewalls of the cross-sections. This damage layer limits the minimum thickness to which a crystalline cross-section can be prepared and affects the quality of the images using high resolution electron microscopy. We report a technique that uses low energy broad ion beam milling to further thin FIB-prepared cross-sections and to decrease the thickness of the damage layer at the sidewalls. Energy filtered transmission electron microscopy has been used to measure the thickness and the amount of preferential milling of the different layers of Spin-Tunnel Junction cross-sections, which consist of metal-insulator-metal layers prepared using this technique.