Minimum detection limit and spatial resolution of thin-sample field-emission electron probe microanalysis

Observation of Fine Distribution of Minor Dopants in an Erbium-Doped Fiber Core using a Sample Thinning Technique for Field Emission Electron Probe Microanalysis

“…Consequently, a higher V acc leads to better spatial resolution. Therefore, to achieve high-resolution analysis, the use of higher V acc is appropriate for thin-sample FE-EPMA, whereas a lower V acc is necessary for bulk-sample FE-EPMA (Kubo et al, 2013).…”

“…However, even the resolution of an FE-EPMA system, ~200 nm, does not meet recent requirements for the microstructural analysis of materials and devices (Hashimoto et al, 2005). As shown in Figure 1, one effective method to achieve higher resolution analysis is to thin the FE-EPMA sample and use a higher acceleration voltage ( V acc ) (Lorimer et al, 1975; Goldstein et al, 1979; Kubo et al, 2013). However, sample thinning may degrade the minimum detection limit (MDL) of FE-EPMA as the sample volume is reduced.…”

“…Our previous work determined the MDL and resolution for thinsample FE-EPMA using an indium gallium phosphide (InGaP) sample thinned to~100 nm. From this, we demonstrated that the detection sensitivity of FE-EPMA was far superior to that of energy-dispersive X-ray spectrometry on a scanning transmission electron microscope (STEM-EDX) (Kubo et al, 2013). In another report, we investigated the mechanism for FE-EPMA by combining high spatial resolution with a low detection limit.…”

“…A major challenge yet to be addressed is the application of thin-sample FE-EPMA to insulating samples. This is because much higher V acc and probe current (I prob ) are required to maximize the advantages of thin-sample FE-EPMA (Kubo et al, 2013). Such measurement conditions cause serious heat damage, such as insulating sample deformation, due to the incident electron beam (Takahashi, 2004).…”

Electron Probe Microanalysis: A Review of the Past, Present, and Future

“…Another area of development will probably be the combined use of the focused ion beam (FIB) and the FEG-EPMA. Indeed, by FIB thinning the samples and analyzing them at high voltages using a FEG-EPMA, Kubo et al (2013) demonstrated a spatial resolution in the range 40–200 nm for an InGaP/GaAs thin sample, with detection limits of 1,000–10,000 ppm and signal-to-noise ratio 13 times higher than that of a STEM-EDS system (on bulk samples such detection limits would be 2 to 3 orders of magnitude lower). Worth mentioning is also the development of three-dimensional microanalysis in dual-beam instruments (i.e., SEM equipped with both EDS and FIB), which will require more sophisticated quantification methods such as the one recently developed by Burdet et al (2014).…”