Techniques for Preparation of Damage-Free Ultrathin Cross-Section TEM Samples from Planar TEM Samples

Abstract As integrated circuit (IC) feature dimensions have shrunk, the need for precise and repeatable sample preparation techniques has increased. In this work, the process of preparation of ultrathin planar-to-cross-section conversion transmission electron microscopy (TEM) samples using a gallium dual-column focused ion beam (FIB)/scanning electron microscope (SEM) system is examined. Sample preparation technique in this paper is aimed at repeatably isolating features in the 5-30 nm range, while limiting common issues such as amorphization, lamella warpage, and the curtain effect (or “curtaining”). This can be achieved through careful selection of FIB parameters including ion beam energy, ion beam current, stage tilt, and deposited protective layer materials and thicknesses, which are all discussed in this work.