Mikrochimica Acta Supplementum 12 A. Boekestein and M. K. Pavicevic (eds.) Electron Microbeam Analysis Springer-Verlag Wien GmbH Dr. Abraham Boekestein Head Department Instrumental Analysis Agricultural Research Department (DLO-NL) State Institute for Quality Control of Agricultural Products (RIKILT-DLO) Wageningen, The Netherlands Prof. Miodrag K. Pavicevic Institute of Mineralogy, University of Salzburg, Austria Permanent address: Faculty of Mining and Geology, University of Belgrade, Yugoslavia This work is subject to copyright. All rights are reserved, whether the whole or part of the material is concerned, specifically those of translation, reprinting, re-use of illustrations, broadcasting, reproduction by photo copying machine or similar means, and storage in data banks. © 1992 Springer-Verlag Wien Typesetting : Asco Trade Typesetting Limited, Hong Kong With 157 Figures ISSN 0026-3672 ISBN 978-3-211-82359-0 ISBN 978-3-7091-6679-6 (eBook) DOI 10.1007/978-3-7091-6679-6 Preface This supplement of Mikrochimica Acta contains selected papers from the Second Workshop of the European Microbeam Analysis Society (EMAS) on "Modern Developments and Applications in Microbeam Analysis", which took place in May 1991 in Dubrovnik (Yugoslavia). EMAS was founded in 1987 by members from almost all European countries, in order to stimulate research, applications and development of all forms of microbeam methods. One of the most important activities EMAS is the organisation of biannual workshops for demonstrating the current status and developing trends of microbeam methods. For this meeting, EMAS chose to highlight the following topics: electron-beam microanalysis (EPMA) of thin films and quantitative analysis of ultra-light elements, Auger electron spectroscopy (AES), electron energy loss spec trometry (EELS), high-resolution transmission electron microscopy (HRTEM), quantitative analysis of biological samples and standard-less electron-beam microanalysis. Seven introductory lectures and almost seventy poster presentations were given by speakers from twelve European and two non-European (U.S.A. and Argentina) countries were made. One cannot assume that all fields of research in Europe were duly represented, but a definite trend is discernible. EPMA with wavelength-dispersive spectrometry (WDS) or energy-dispersive spectrometry (EDS) is the method with by far the widest range of applications, followed by TEM with EELS and then AES. There are also interesting suggestions for the further development of new appa ratus with new fields of application. Applications are heavily biased towards materials science (thin films in microelectronics and semicon ductors), ceramics and metallurgy, followed by analysis of biological and mineral samples. This issue contains the full texts of five introductory lectures and 25 brief articles. Sixteen contributions relate to the refinement of methods and procedures and nine of these are concerned with important applications in various fields. All submissions have been refereed according to the usual procedures. At the end of this issue is an overview of all the published work. We hope that these contributions to the field of electron microbeam analysis will be found to be useful. February 1992 A. Boekestein and M. K. Pavicevic Participants in the EMAS '91 Meeting in Dubrovnik Contents Listed in Current Contents EPMA - A Versatile Technique for the Characterization of Thin Films and Layered Structures. P. Willich . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 1 Quantitative EPMA of the Ultra-Light Elements Boron Through Oxygen. G. F. Bastin, H. J. M. Heijligers . . . . . . . . . . . . . . . . . . . .. 19 Auger Microscopy and Electron Probe Microanalysis. J. Cazaux ....................... . 37 Quantitative X-Ray Microanalysis of Ultra-Thin Resin-Embedded Biological Samples. H. Y. Eler, S. M. Wilson, W A. P. Nicholson, J. D. Pediani, S. A. McWilliams, D. McEwan Jenkinson, Ch. J. Kenyon . . . . . . . . 53 Analytical and High-Resolution Electron Microscopy Studies at Metal/Ceramic Interfaces. M. Ruhle. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 75 Quantitative Electron Probe Microanalysis of Multi-layer Structures. G. F. Bastin, J. M. Dijkstra, H. J. M. Heijliger, D. Klepper ...... 93 Comparison of (/J (pz) Curve Models in EPMA. J. A. Riveros, G. E. Castellano, J. C. Trincavelli ..... . 99 Quantitative Electron Probe Microanalysis: New Accurate (/J (pz) Description. C. Merlet . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 107 A Modular Universal Correction Procedure for Quantitative EPMA. /. Farthing, G. Love, V. D. Scott, C. T. Walker . . . . . . . . . . . . . 117 Monte Carlo Simulation of Backscattered and Secondary Electron Profiles. Ch. Eisenschmidt, U. Werner ....... . . . . . . . . . . . . . . . 125 An Electron Scattering Model Applied to the Determination of Film Thicknesses Using Electron Probe Microanalysis. H.-J. August ............................... 131 Calculation of Depth Distribution Functions for Characteristic and for Continuous Radiation. H.-J. August . . . . . . . . . . . . . . . . . . . . . . . . . . . 139 A Method for In-Situ Calibration of Semiconductor Detectors. J. Wernisch, A. Schonthaler, H.-J. August. . . . . . . . . . . . 147 VIII Contents Background Anomalies in Electron Probe Microanalysis Caused by Total Reflection. W P. Rehbach, P. Karduck . . . . . . . . . . . . . . . . . . . . . . . 153 Automatic Analysis of Soft X-Ray Emission Spectra Obtained by EPMA. /. A. Slavic, J. /. Slavic, /. A. Grzetic, M. K. Pavicevic . . . . . . . . . 161 The Scanning Very-Low-Energy Electron Microscopy (SVLEEM). /. MiUlerova, M. Lenc . . . . . . . . . . . . . . . . . . . . . . . 173 To the Backscattering Contrast in Scanning Auger Microscopy. L. Frank. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 179 Design Consideration Regarding the Use of an Accelerator on Mass Spectrometer in Ion Microanalysis. K. M. Subotic, M. K. Pavicevic .. . . . . . . . . . . . . . . . . . . . 187 Accurate Estimation of Uncertainties in Quantitative Electron Ener gy-Loss Spectrometry. J. J. Y. Van Puymbroeck, W. A. Jacob, P. J. M. Van Espen . . . . . . . 191 An EELS System for a TEM/STEM-Performance and Its Use in Mate rials Science. R. Schneider, W Rechner . . . . . . . . . . . . . . . . . . . . . .. 197 Quantitative X-Ray Microanalysis of Bio-Organic Bulk Specimens. A. Boekestein . . . . . . . . . . . . . . . . . . . . . . . . . . . . .. 205 Quantitative Analysis of (Y203)x (ZrOJ1-x Films on Silicon by EPMA. N. Ammann, A. Lubig, P. Karduck . . . . . . . . . . . . . . . . . . . 213 EPMA of Surface Oxide Films. P. Willich, K. Schiffmann .. 221 Non-Destructive Determination of Ion-Implanted Impurity Distribution in Silicon by EPMA. A. P. Alexeyev. . . . . . . . . . . . . . 229 An Electron Spectroscopy Study of a-SiNx Films. A. G. Fitzgerald, H. L. L. Watton, M. J. Rose. . .......... 235 Electron Probe Microanalysis of Glass Fiber Optics. M. Kern, E. Perman, P. Pavli . . . . . . . . . 241 Quantitative Microanalysis of Low Concentrations of Carbon III Steels. J. Ruste .............. . 247 Contents IX Electron Configuration of the Valence-Conduction Band of the Mineral Wustite. D. M. Timotijevic, M. K. Pavicevic . .. 255 Structural Analysis of Silver Halide Cubic Microcrystals with Epitaxial or Conversion Growths by STEM-EDX. S. Wu, A. Van Daele, W Jacob, R. Gijbels, A. Verbeeck, R. De Keyzer 261 Characterization of the Bony Matrix of the Otic Capsule in Human Fetuses by EPMA. S. S. Montoro, F F Declau, P. J. Van Espen . . . . . . . . . . . . . . 269 Overview. M. K. Pavicevic, A. Boekestein . ..................... 275 Mikrochim. Acta (1992) [Supp!.] 12: 1-17 © Springer-Verlag 1992 EPMA-A Versatile Technique for the Characterization of Thin Films and Layered Structures Peter Willich Fraunhofer-Institut fUr Schicht-und Oberflachentechnik, P.o. Box 540645, D-W-2000 Hamburg 54, Federal Republic of Germany Abstract. Electron probe microanalysis (EPMA) is presented as a quantitative technique of near-surface chemical characterization. Three principle operation modes are discussed: (1) "Thick" films (> 100 I1g/cm2, 0.2 11m for a density of 5 g/cm3) are studied by use of a sufficiently low electron energy. (2) The com bined determination of film thickness and composition is applied to "thin" films and multilayers « 250 I1g/cm2, 0.5 11m for a density of 5 g/cm3). Relatively fast analysis at a single electron energy is possible under certain restrictions. (3) The universal approach of non-destructive in-depth analysis is based on combining experiments performed at different electron energies. The operation modes are described with respect to experimental procedures, data reduction models, preci sion, accuracy and the range of practical applications. EPMA is also related to other techniques of thin film and surface analysis. Key words: electron probe microanalysis (EPMA), thin films, multilayers, film thickness, non-destructive in-depth analysis, ultralight elements. For almost 40 years electron probe microanalysis has been developed as a powerful tool for the local chemical characterization of solids. The majority of applications, in combination with scanning electron microscopy, is directed to analysis with a lateral resolution of about 111m, whereas the aspect of near-surface analysis is frequently neglected. Although interesting attempts in this direction were started as early as the beginning of the 1960s, as listed by Heinrich [IJ, these procedures and models did not succeed as routine tools for the characterization of thin film samples. This was due to the fact that none of them proved to be sufficiently general and quantitative. A new era of EPMA applied to thin film materials started in 1984, when Pouchou and Pichoir [2J presented a thin film correction model based on a realistic description of $(pz) depth distribution functions. Moreover, Pouchou and Pichoir proposed a general procedure for analysis of samples of which the composi tion varied in depth. In the following years, similar thin film applications have been discussed using completely different $(pz) data reduction models [3-5J, originally developed to improve the accuracy of conventional "bulk" EPMA. 2 P. Willich In addition to the development of general and sufficiently accurate correction models, EPMA of thin films and layered structures has been stimulated by recent instrumental and experimental improvements. This concerns the reliable operation ofEPMA instruments at low electron energies, typically below 10 keY, the handling of contamination phenomena [6], and, with respect to wavelength dispersive X-ray spectrometry (WDS), the significantly improved sensitivity for the determination of soft X-rays by use of synthetic multilayer monochromators. Quantitative EPMA of ultralight elements (boron-oxygen), which play an important role in thin film technology, has now reached a remarkable degree of precision and accuracy [7]. Thin film analysis has to be regarded as an essential part of thin film technology, the importance of which is rapidly increasing in many fields of application. An ideal technique of analysis should be applicable to a wide range of materials and layered configurations, easy to operate, quantitative, and sufficiently local with respect to lateral resolution and depth of analysis. From this point of view the recent develop ments of EPMA have to be considered. This paper reviews, by examples of techno logical interest, the various operation modes of EPMA applied to thin films and stratified materials. The characteristics of EPMA are discussed in relation to the features of other techniques frequently applied to thin film and surface analysis. EPMA in Comparison with Other Techniques of Thin Film Analysis Table 1 gives an overview of a number of techniques to carry out analysis of surfaces and near-surface regions. The data of Table 1 are mainly drawn from a recent review of Werner and Torrisi [8], supplemented by experience of our own laboratory. In Table 1. Comparison of some techniques applied to local analysis of thin films and surfaces Depth Lateral Depth Quantitative Technique resolution resolution Elements LLD2 [JIg/g] profiling analysis! XRF >5 JIm >5mm Z>9 >5 no <3% EPMA-WDS 0.1-2 J.lm >0.5J.1m Z>3 >20 (limited) <5% AES 1nm >0.1 J.lm Z>3 >1000 sputtering 10-20% XPS 2nm >100 J.lm Z>2 >1000 sputtering 10-20% RBS 2-20 nm >100 J.lm Z>5 >1000 non-destr. <5% ERD 2-20 nm >100 J.lm hydrogen >1000 non-destr. <10% SIMS 2nm >0.1 J.lm all <1 sputtering difficult SNMS/SALI 2nm >1J.1m all >1 sputtering 5-20% LAMMA >0.5 JIm >3 JIm all <1 no difficult ! Accuracy without matched standards 2 LLD = Lower limit of detection Acronyms: XRF X-ray fluorescence, EPMA-WDS electron probe microanalysis-wavelength dispersive spectrometry, AES Auger electron spectroscopy, XPS X-ray photoelectron spectroscopy, RBS Rutherford backscattering spectrometry, ERD elastic recoil detection, SIMS secondary ion mass spectrometry, SNMS secondary neutral mass spectroscopy, SALI surface analysis by laser ionization, LAMMA laser microprobe mass analysis