In-situ Sample Preparation of Oxidizing and Contaminating Samples for High Quality EDS and WDS Quantification Using FIB-SEM

Abstract

Energy dispersive and wavelength dispersive X-ray spectroscopy (EDS and WDS) are very important tools in materials research to obtain information about the chemical composition of a sample. A planar and clean surface within a homogeneous material is essential to achieve a proper quantitative analysis with those methods. Often, surfaces tend to contaminate or oxidize very fast under atmospheric conditions. Usually samples cannot be transferred to the microscope without exposure to these conditions. Electron microscopes themselves provide a high vacuum free of contamination. Surfaces prepared with a focused ion beam (FIB) are smooth and sufficiently free of contamination, but are not perpendicular to the electron beam. In this work, an in situ preparation procedure was developed to improve the accuracy of quantitative analytical results using a FIB-SEM equipped with EDS and WDS. For this, the geometric obstacles had to be bypassed to achieve a FIB-prepared surface free of contamination or oxidization, perpendicular to the electron beam and suitable for the analysis.