Electron Probe Microanalysis of Thin Films and Multilayers Using the Computer Program XFILM

Llovet, Xavier; Merlet, Claude

doi:10.1017/s1431927609991218

Cited by 49 publications

(43 citation statements)

References 26 publications

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“…To determine the thickness of the self‐supporting films, M α x‐ray intensities emitted from the samples were recorded at several electron energies and compared with those emitted from thick standards. The variation of the ratio of the x‐ray intensities (also called k‐ratio) was analyzed with the help of a thin film electron probe microanalysis program . The uncertainty in the thickness determination was estimated to be better than 5% …”

Section: Methodsmentioning

confidence: 99%

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Measurements of absolute Mα x‐ray production cross sections of heavy elements Au, Pb, Bi, and U by electron impact

Merlet

Moy

Llovet

et al. 2014

Surface & Interface Analysis

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Absolute Mα x‐ray production cross sections have been measured and calculated for heavy elements Au, Pb, Bi, and U for electron incident energies from the ionization threshold up to 38 keV. The experimental cross sections were deduced from M x‐ray intensities emitted from ultrathin samples of the elements of interest deposited onto self‐supporting C films. The measurements were performed using two electron microprobes and several wavelength‐dispersive spectrometers. X‐ray intensities were converted into x‐ray production cross sections by using estimated values of the number of incident electrons, target thickness, and spectrometer efficiency. Experimental results are compared with calculated cross sections using different predictive formulae. Good agreement is found between the measured cross sections and the predictions from the distorted‐wave Born approximation, which indicates that this approximation is suited for the calculation of M‐shell ionization cross sections of heavy elements. Copyright © 2014 John Wiley & Sons, Ltd.

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Section: Methodsmentioning

confidence: 99%

“…The variation of the ratio of the x‐ray intensities (also called k‐ratio) was analyzed with the help of a thin film electron probe microanalysis program . The uncertainty in the thickness determination was estimated to be better than 5% …”

Section: Methodsmentioning

confidence: 99%

Measurements of absolute Mα x‐ray production cross sections of heavy elements Au, Pb, Bi, and U by electron impact

Merlet

Moy

Llovet

et al. 2014

Surface & Interface Analysis

Self Cite

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“…Extensive experimental databases have become available in recent years for the purpose of assessing the reliability of thin film programmes [40]. Evidently, they can also be used to assess the performance of MC simulation programmes [28].…”

Section: Thin Filmsmentioning

confidence: 99%

PENEPMA: a Monte Carlo programme for the simulation of X-ray emission in EPMA

Llovet

Salvat

2016

IOP Conf. Ser.: Mater. Sci. Eng.

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Abstract. The Monte Carlo programme PENEPMA performs simulations of X-ray emission from samples bombarded with electron beams. It is both based on the general-purpose Monte Carlo simulation package PENELOPE, an elaborate system for the simulation of coupled electron-photon transport in arbitrary materials, and on the geometry subroutine package PENGEOM, which tracks particles through complex material structures defined by quadric surfaces. In this work, we give a brief overview of the capabilities of the latest version of PENEPMA along with several examples of its application to the modelling of electron probe microanalysis measurements.

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“…Similarly for a buried layer, an increase in the energy of the incident electrons results in an increase followed by a decrease of the k-ratio. The observed variation of the k-ratio with incident electron energy of the layers and of the substrate is the input of the EPMA quantification code, which determines the thickness of the layers by fitting the experimental k-ratios with a Monte Carlo (MC) simulation code [5,6] or with an analytical x-ray emission model [1][2][3][4]. The accuracy of the result is therefore directly dependent on the accuracy of the theoretical model.…”

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confidence: 99%

Quantitative X-ray Microanalysis of Multi-layered Specimens: Capability and Accuracy

Merlet¹

2013

Microsc Microanal

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The determination of the thickness and composition of thin layer and multilayer deposited on substrates is an important area in semiconductor research and thin-film technology. Electron probe microanalysis (EPMA), originally developed to determine the composition of the bulk samples at the micron scale, has become a well established technique to determine the compositions and the thickness of thin multilayer deposited on a substrate [1][2][3][4][5][6][7]. This technique can be used to determine the film thickness in a range of a few micrometers to a monolayer. Measurements of thin-layer thicknesses can also be performed by some others techniques such as Rutherford backscattering spectrometry (RBS), Atomic Force Microscopy (AFM), Secondary Ion Mass spectrometry (SIMS), optical interferometry (OI), x-ray fluorescence XRF etc. However in comparison to the other techniques and beyond the microscopic aspect of the method, and also the fact that it is a nondestructive technique, one of the advantages of the EPMA method is the opportunity to have simultaneously the layer thickness and the composition with accuracies similar to the one obtained on bulk sample. In addition, the equipment is available in many laboratories, i.e., a scanning electron microscope with an Energy Dispersive spectrometer (EDS) or more rarely an electron probe with Wavelength Dispersive spectrometers (WDS).The thin-multilayer method by EPMA is based on the comparison of the ratios of x-ray intensities (k-ratio) emitted by the elements of the various layers to those emitted from bulk standards under same experimental conditions. By varying the energy of the incident electrons, and thus the excitation depths, the different layers can be analyzed. Typical incident electrons energies of 5-40 keV have excitation depths from 0.2-10 μm. For an element of a thin layer at the surface, an increase of the energy of the incident electrons increases the excitation depths and as a result induces a decrease of the k-ratio. Similarly for a buried layer, an increase in the energy of the incident electrons results in an increase followed by a decrease of the k-ratio. The observed variation of the k-ratio with incident electron energy of the layers and of the substrate is the input of the EPMA quantification code, which determines the thickness of the layers by fitting the experimental k-ratios with a Monte Carlo (MC) simulation code [5,6] or with an analytical x-ray emission model [1][2][3][4]. The accuracy of the result is therefore directly dependent on the accuracy of the theoretical model. Since quantitative results are obtained with the help of numerical iterative procedures or with a manual trial and error approach, in practice, only analytical models are used. Monte Carlo (MC) simulation code, not always more accurate [7], but very time consuming, are generally used to optimize or assess analytical models.To convert the measured k-ratio from elements of the layers in thicknesses and compositions, an analytical x-ray emission model requires an accurate descr...

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Electron Probe Microanalysis of Thin Films and Multilayers Using the Computer Program XFILM

Cited by 49 publications

References 26 publications

Measurements of absolute Mα x‐ray production cross sections of heavy elements Au, Pb, Bi, and U by electron impact

Measurements of absolute Mα x‐ray production cross sections of heavy elements Au, Pb, Bi, and U by electron impact

PENEPMA: a Monte Carlo programme for the simulation of X-ray emission in EPMA

Quantitative X-ray Microanalysis of Multi-layered Specimens: Capability and Accuracy

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