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Enhanced information on SEM through combined complimentary methods

M. Patzschke

Bruker Nano GmbH, Am Studio 2D, 12489 Berlin, Germany

Email: max.patzschke@bruker.com

BY MSSA TECH FORUM

Energy dispersive X-ray spectroscopy (EDS) using silicon drift detectors (SDD) has become an established and effective method for element analysis in electron microscopy. Today’s state of the art SDDs outperform Si(Li) technology in pulse throughput and are approaching the theoretical limit in energy resolution. To overcome the physical detection limits using EDS on SEM, the single area SDD detector technology has been complemented by additional techniques in recent years.

 

Due to the full integration of EDS, WDS, EBSD and Micro-XRF under the new ESPRIT 2 software suite on one SEM, combined data can be obtained by these complementary methods  without changing the equipment and sample position. Using Electron Back Scattered  Diffraction (EBSD) technique, microstructure and crystallographic texture evolution can be quantified. Furthermore EBSD can be combined with EDS for phase identification analysis as well as for automatic phase discrimination of similar crystallographic phases. Electron  transparent samples can also be analyzed in transmission mode with a lateral spatial resolution down to a few nanometers. Micro-XRF use a focused X-ray photon source for specimen excitation resulting in higher sensitivity for various elements. The detection limits, particularly for elements higher than atomic number 20 are significantly lower and can go down to 10 ppm (μg/g). Micro-XRF on SEM is often used to find trace elements that cannot be detected with EDS on SEM. This enhances the analytical accuracy through combination of quantitative results from both electron and X-ray induced spectra.

 

The new QUANTAX WDS system enables ultra-sensitive, high spectra resolution X-ray microanalysis in the low energy range. The spectrometer achieves energy resolutions in the range of 4 eV for Si Kα radiation. Measurements can be performed with WDS and EDS on the same spot and results can be combined for improved reliability of quantification.

The Micro-CT for SEM adds true 3D microscopy to the SEM. It enables non-destructive measurement and volume visualization of a sample’s internal microstructure with a resolution down to 400 nm pixel size. This gives information on a sample‘s internal morphology in 2D and 3D without sample preparation.

 
In the presentation the combination of these techniques on a variety of specimens will be shown. Polymers, geological and biological samples were investigated exploiting the strength of each technique, combining them and demonstrating the advantages of a comprehensive analysis on the SEM. The enhanced analytical power through synergistic combination of results delivered by different methods, provides the possibility to improve data and sample understanding.

 November 06, 2015
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