Comparison of the Detection Limits of EDS and EELS in S/TEM

Harrach, HS von; Klenov, Dmitri O.; Freitag, Bert; Schloßmacher, P.; Collins, Peter C.; Fraser, HL

doi:10.1017/s1431927610058940

Cited by 32 publications

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“…Electron energy loss spectroscopy (EELS) provides a complementary approach for determining three dimensional elemental distributions within the STEM 8 . In this technique the energy losses of the incident electron beam are used to determine the composition of the sample and this has the advantage of higher signal-to-noise ratio than is often obtained by EDX spectroscopy 9 . The disadvantage of EELS is that multiple scattering considerations impose stringent limits on the specimen thickness, and in several situations analysis is complicated by the presence of delayed onset edges or overlapping spectral features.…”

Section: Introductionmentioning

confidence: 99%

“…The disadvantage of EELS is that multiple scattering considerations impose stringent limits on the specimen thickness, and in several situations analysis is complicated by the presence of delayed onset edges or overlapping spectral features. Thus, EDX spectroscopy is often better suited to studying heavy elements such as those often associated with catalytic or plasmonic nanoparticle systems 9 The ideal sample geometry for EDX tomography consists of a needle shaped sample suspended in a vacuum and oriented along the tomographic tilt axis 4 . This situation ensures that there is no shadowing of the EDX detectors at any tilt angle by either the sample or the specimen holder.…”

Section: Introductionmentioning

confidence: 99%

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Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Slater

Lewis

Haigh

2016

JoVE

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Energy dispersive X-ray spectroscopy within the scanning transmission electron microscope (STEM) provides accurate elemental analysis with high spatial resolution, and is even capable of providing atomically resolved elemental maps. In this technique, a highly focused electron beam is incident upon a thin sample and the energy of emitted X-rays is measured in order to determine the atomic species of material within the beam path. This elementally sensitive spectroscopy technique can be extended to three dimensional tomographic imaging by acquiring multiple spectrum images with the sample tilted along an axis perpendicular to the electron beam direction.Elemental distributions within single nanoparticles are often important for determining their optical, catalytic and magnetic properties. Techniques such as X-ray tomography and slice and view energy dispersive X-ray mapping in the scanning electron microscope provide elementally sensitive three dimensional imaging but are typically limited to spatial resolutions of > 20 nm. Atom probe tomography provides near atomic resolution but preparing nanoparticle samples for atom probe analysis is often challenging. Thus, elementally sensitive techniques applied within the scanning transmission electron microscope are uniquely placed to study elemental distributions within nanoparticles of dimensions 10-100 nm.Here, energy dispersive X-ray (EDX) spectroscopy within the STEM is applied to investigate the distribution of elements in single AgAu nanoparticles. The surface segregation of both Ag and Au, at different nanoparticle compositions, has been observed.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Slater

Lewis

Haigh

2016

JoVE

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“…Recent advances in AEM hardware have resulted in commercially available systems that can provide $0.9 srad solid angle of collection by integrating four discrete silicon drift detectors (SDDs) into the objective lens region of an AEM [26][27][28], compared to traditional STEM-EDS systems that typically collect $0.1 srad. Combining high-brightness sources now available, approximately 5Â brighter than traditional Schottky emitters, with advanced data post-processing techniques, a modern AEM is capable of greatly improved materials analysis and more readily explain structureproperty relationships, such as the nature of grain boundaries in 14YWT and their relation to creep.…”

Section: Introductionmentioning

confidence: 99%

A review of advantages of high-efficiency X-ray spectrum imaging for analysis of nanostructured ferritic alloys

Parish

Miller

2015

Journal of Nuclear Materials

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a b s t r a c tNanostructured ferritic alloys (NFAs) exhibit complex microstructures consisting of 100-500 nm ferrite grains, grain boundary solute enrichment, and multiple populations of precipitates and nanoclusters (NCs). Understanding these materials' excellent creep and radiation-tolerance properties requires a combination of multiple atomic-scale experimental techniques. Recent advances in scanning transmission electron microscopy (STEM) hardware and data analysis methods have the potential to revolutionize nanometer-to micrometer-scale materials analysis. Modern high-brightness, high-X-ray collection STEM instruments are capable of enabling advanced experiments, such as simultaneous energy dispersive X-ray spectroscopy and electron energy loss spectroscopy spectrum imaging at nm to sub-nm resolution, that are now well-established for the study of nuclear materials. In this paper, we review past results and present new results illustrating the effectiveness of latest-generation STEM instrumentation and data analysis.

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“…However, XEDS may not be the method of choice for the following reasons. First, it is not very sensitive to light elements, (e.g., B, C) [4] [5], which are typically found in semiconductor devices. Second, peaks of a number of elements which are used in device structures overlap in the XEDS spectrum.…”

mentioning

confidence: 99%

“…To answer this, EELS should be used as a complimentary method to provide the full elemental analysis. It is more sensitive to light atomic weight elements [4] [5]. In the STEM configuration only the region of the sample under the electron probe contributes to the EELS spectrum.…”

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confidence: 99%

Application of EFTEM and XEDS Elemental Mapping to Characterization of Nanometer Devices in Semiconductor Wafer-Foundries

2015

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Precise characterization of the elemental distribution in the nanometer semiconductor device with high spatial resolution is an essential element of the Physical Failure Analysis (PFA) Laboratory to help develop and manufacture next generation of devices [1][2] [3]. Nowadays state-of-the-art analytical TEM instruments possess the x-ray energy dispersive spectroscopy (XEDS) and/or the electron energy loss spectroscopy (EELS) capabilities to fulfill this goal. The acquisition of XEDS spectra on modern instruments is relatively straightforward and does not require an extensive training of the TEM analyst. It has high sensitivity to species with medium and high atomic number [4] [5]. These features made it attractive for application in PFA. However, XEDS may not be the method of choice for the following reasons. First, it is not very sensitive to light elements, (e.g., B, C) [4] [5], which are typically found in semiconductor devices. Second, peaks of a number of elements which are used in device structures overlap in the XEDS spectrum. Examples include Cu (Kα 1 ) vs. Ta (Lα 1 ), P (Kα 1,β1 ) vs. Pt ( Mα1, β1) or Zr (Lα1 , β1), etc. This makes it challenging to directly interpret results without further processing. Third, spurious x-ray peaks originating from excitations of components inside the electron microscope can also contaminate the observed XEDS spectrum. To answer this, EELS should be used as a complimentary method to provide the full elemental analysis. It is more sensitive to light atomic weight elements [4][5]. In the STEM configuration only the region of the sample under the electron probe contributes to the EELS spectrum. Therefore EELS data provide results with higher spatial resolution as compared to XEDS. The energy resolution of the EELS spectrum in non-aberrated instruments is ΔE<1eV, which makes it possible to detect individual edges of most elements used in semiconductor structures without having to deconvolute the edges. However, the analyzed samples need to be thin, i.e. less than 50nm, and have surfaces free of redeposition. Moreover, subtraction of the spectrum background, processing and interpretation of the results requires an in-depth understanding of the analytical TEM configuration and electron diffraction physics. Since no single method can provide a full solution of the problem, analysts in the PFA Lab are challenged to find the optimum plan to analyze the problem in the shortest time.Presented here are examples of how we combine both methods to quickly provide engineering solutions for semiconductor process integration on an SRAM device. Fig. 1 displays a TEM, an overlay and individual EFTEM elemental maps, which revealed details of elemental compositions inside the bridging portion between the dummy gates. Fig. 2 is a STEM on the same structure, and XEDS counterparts acquired by a Super-X with Bruker Esprit analysis software. Even with the primitive version of EELS by EFTEM mapping, details of the defect can still be delineated (arrowed). In contrast, the XEDS elemental mapping yield...

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Comparison of the Detection Limits of EDS and EELS in S/TEM

Abstract: Extended abstract of a paper presented at Microscopy and Microanalysis 2010 in Portland, Oregon, USA, August 1 – August 5, 2010.

Cited by 32 publications

References 0 publications

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

Energy Dispersive X-ray Tomography for 3D Elemental Mapping of Individual Nanoparticles

A review of advantages of high-efficiency X-ray spectrum imaging for analysis of nanostructured ferritic alloys

Application of EFTEM and XEDS Elemental Mapping to Characterization of Nanometer Devices in Semiconductor Wafer-Foundries

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