EPMA of submicron coatings containing ultralight elements

Abstract

Materials containing ultralight elements (B, C, N, O) in combination with a metal are of considerable interest in thin film technology. Quantitative electron probe microanalysis of the coatings should be independent of the substrate and has to be carried out under the condition that the ultimate depth of x-ray emission (Rx) is within the provided film thickness of 0.2-0.8 μm. Rx, for an element (critical excitation energy Ec) in a specified matrix is controlled by the energy (E0) of the primary electrons. EPMA of high atomic number elements (Ec = 2-7 keV), under the condition of Rx < 1 μm, frequently requires operation at a low overvoltage of E0/Ec < 2. Consequendy, tne x-ray intensities are very low and the analytical sensitivity is drastically reduced. For the ultralight elements the strong effects oft x-ray absorption always lead to a shallow depth of x-ray emission, even at a high overvoltage.