High-precision chemical quantification of contaminated or geometrically unsuitable samples using in situ FIB-SEM preparation with coupled EDS and WDS

Abstract

In quantitative measurements with EDS and WDS in a SEM, factors like conductivity, contamination, homogeneity, and sample geometry significantly affect results. WDS requires a high-quality sample surface to achieve accuracy below 1%, which is why it was used here to verify new procedures. Oxidation, carbon contamination, and non-planar samples (e.g., particles) reduce measurement quality. FIB enables preparation of smooth, planar cross-sections. Using a coupled FIB-SEM allows contamination-free, in-situ preparation and analysis in vacuum, improving measurement quality. Since FIB cross-sections are usually not perpendicular to the electron beam, a new procedure was developed: samples are prepared at -10° tilt and then tilted to +28° for analysis, aligning the cross-section perpendicular to the beam. This method yielded reliable quantification for oxidized samples (100.23 wt.% total), while unprepared showed large deviations. FIB-prepared particles gave 100.99 wt.% without oxygen contamination. This procedure significantly enhances the quality of EDS and WDS quantification for samples initially unsuitable for analysis