High-density FIB-SEM 3D nanotomography: with applications of real-time imaging during FIB milling

Abstract

Introduction The ability to acquire, display, and interrogate multi-dimensional volumetric data sets has been well established through various scientific disciplines. The medical field in particular has exposed the public to tomographic methods through now common medical procedures such as computed axial tomography (CAT), magnetic resonance imaging (MRI), and positron emission tomography (PET). In an analogous fashion the focused ion beam (FIB) and scanning electron microscope (SEM) can combine to generate tomographic data using the FIB-SEM platform. Early work completed by a small number of researchers gives an indication of the variety of information that can be obtained by FIB based tomography: Uchick et al. [1] and Kotula et al. [2] have produced secondary electron (SE) and X-ray images (XEDS) of 3D structures; Dunn et al. [3] have created 3D mass spectral images using planar FIB etching (FIB-SIMS); Inkson et al. [4] and Sakamoto et al. [5] have published 3D reconstructions based on secondary electron images, and Principe [6] has demonstrated the application of FIB-Auger spectroscopic 3D reconstruction at 10 nm resolution. Konrad et al. [7] have demonstrated sequential automated acquisition of 3D electron backscatter pattern (EBSP) tomographic data. This prior work has shown that FIB based tomographic methods have volumetric data resolution down to 20 nm or less (i.e., FIB-SE, FIB-Auger) and have tremendous potential for a variety of investigations in both material science and biology.