1、BSI Standards PublicationBS ISO 13424:2013Surface chemical analysis X-ray photoelectron spectroscopy Reporting of results of thin-film analysisBS ISO 13424:2013 BRITISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 13424:2013. The UK participation in its preparation
2、was entrusted to TechnicalCommittee CII/60, Surface chemical analysis.A list of organizations represented on this committee can be obtained on request to its secretary.This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct appli
3、cation. The British Standards Institution 2013.Published by BSI Standards Limited 2013ISBN 978 0 580 68394 7ICS 71.040.40Compliance with a British Standard cannot confer immunity from legal obligations.This British Standard was published under the authority of the Standards Policy and Strategy Commi
4、ttee on 31 October 2013.Amendments/corrigenda issued since publicationDate T e x t a f f e c t e dBS ISO 13424:2013 ISO 2013Surface chemical analysis X-ray photoelectron spectroscopy Reporting of results of thin-film analysisAnalyse chimique des surfaces Spectroscopie de photolectrons X Rapport des
5、rsultats de lanalyse de films mincesINTERNATIONAL STANDARDISO13424First edition2013-10-01Reference numberISO 13424:2013(E)BS ISO 13424:2013ISO 13424:2013(E)ii ISO 2013 All rights reservedCOPYRIGHT PROTECTED DOCUMENT ISO 2013All rights reserved. Unless otherwise specified, no part of this publication
6、 may be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting on the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below or ISOs member body in the country of
7、the requester.ISO copyright officeCase postale 56 CH-1211 Geneva 20Tel. + 41 22 749 01 11Fax + 41 22 749 09 47E-mail copyrightiso.orgWeb www.iso.orgPublished in SwitzerlandBS ISO 13424:2013ISO 13424:2013(E) ISO 2013 All rights reserved iiiContents PageForeword ivIntroduction v1 Scope . 12 Normative
8、references 13 Terms and definitions . 14 Abbreviated terms 15 Overview of thin-film analysis by XPS 15.1 Introduction 15.2 General XPS 35.3 Angle-resolved XPS 35.4 Peak-shape analysis 35.5 Variable photon energy XPS 35.6 XPS with sputter-depth profiling 36 Specimen handling . 47 Instrument and opera
9、ting conditions 47.1 Instrument calibration . 47.2 Operating conditions . 48 Reporting XPS method, experimental conditions, analysis parameters, and analytical results 58.1 XPS method for thin-film analysis 58.2 Experimental conditions 58.3 Analysis parameters . 68.4 Examples of summary tables 78.5
10、Analytical Results 9Annex A (informative) General XPS 10Annex B (informative) Angle-resolved XPS .18Annex C (informative) Peak-shape analysis .24Annex D (informative) XPS with sputter-depth profiling 37Bibliography .40BS ISO 13424:2013ISO 13424:2013(E)ForewordISO (the International Organization for
11、Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee has been established has the r
12、ight to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical standardization.The procedur
13、es used to develop this document and those intended for its further maintenance are described in the ISO/IEC Directives, Part 1. In particular the different approval criteria needed for the different types of ISO documents should be noted. This document was drafted in accordance with the editorial r
14、ules of the ISO/IEC Directives, Part 2 (see www.iso.org/directives). Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. ISO shall not be held responsible for identifying any or all such patent rights. Details of any patent rights ide
15、ntified during the development of the document will be in the Introduction and/or on the ISO list of patent declarations received (see www.iso.org/patents). Any trade name used in this document is information given for the convenience of users and does not constitute an endorsement.For an explanatio
16、n on the meaning of ISO specific terms and expressions related to conformity assessment, as well as information about ISOs adherence to the WTO principles in the Technical Barriers to Trade (TBT) see the following URL: Foreword - Supplementary informationThe committee responsible for this document i
17、s ISO/TC 201, Surface chemical analysis, Subcommittee SC 7, Electron spectroscopies.iv ISO 2013 All rights reservedBS ISO 13424:2013ISO 13424:2013(E)IntroductionX-ray photoelectron spectroscopy (XPS) is widely used for the characterization of surfaces of materials, especially for overlayer thin film
18、s on a substrate. The chemical composition of the near-surface region of a thin film can be determined by XPS. If the film has a uniform thickness and the thickness is less than about three times the mean escape depth (MED) for the measured photoelectrons, the film thickness and the depth distributi
19、on of elements or chemical states of elements in the film can be determined by angle-resolved XPS or peak-shape analysis . For thicker films, the depth distributions of elements in the film can be obtained by sputter-depth profiling. Possible lateral inhomogeneities in film thicknesses or depth prof
20、iles can be determined if the XPS system has sufficient lateral resolution. These XPS applications are particularly valuable for characterizing thin-film nanostructures since the MED is typically less than 5 nm for many materials and common XPS measurement conditions.Clauses 6 and 7 of this Internat
21、ional Standard provide guidance to the operator of an XPS instrument in making efficient measurements for determining meaningful chemical compositions and film thicknesses for overlayer films on a substrate. Clause 8 of this International Standard shows the information to be included in reports of t
22、he measurements and the analyses of the XPS data. Annex A, Annex B, Annex C, and Annex D provide supplementary information on methods of data analysis for different types of XPS measurements on thin-film samples. ISO 2013 All rights reserved vBS ISO 13424:2013BS ISO 13424:2013Surface chemical analys
23、is X-ray photoelectron spectroscopy Reporting of results of thin-film analysis1 ScopeThis International Standard specifies the minimum amount of information required in reports of analyses of thin films on a substrate by XPS. These analyses involve measurement of the chemical composition and thickne
24、ss of homogeneous thin films, and measurement of the chemical composition as a function of depth of inhomogeneous thin films by angle-resolved XPS, XPS sputter-depth profiling, peak-shape analysis, and variable photon energy XPS.2 Normative referencesThe following documents, in whole or in part, are
25、 normatively referenced in this document and are indispensable for its application. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies.ISO 18115-1:2010, Surface chemical analysis Vocabulary Pa
26、rt 1: General terms and terms used in spectroscopy3 Terms and definitionsFor the purposes of this document, the terms and definitions in ISO 18115-1:2010 apply.4 Abbreviated termsAES Auger electron spectroscopyARXPS Angle-resolved X-ray photoelectron spectroscopyIMFP Inelastic mean free pathMED Mean
27、 escape depthRSF Relative sensitivity factorTRMFP Transport mean free pathXPS X-ray photoelectron spectroscopy5 Overview of thin-film analysis by XPS5.1 IntroductionXPS analyses of thin films on substrate can provide information on the variation of chemical composition with depth and on film thickne
28、sses. Several XPS methods can be used if the total film thickness is less than three times the largest MED for the detected photoelectrons. The MED for particular photoelectrons is a function of the IMFP and the emission angle of the photoelectrons with respect to the surface normal. The IMFP depend
29、s on the photoelectron energy and the material. MED values can be obtained from a database.1A simple analytical formula for estimating MEDs has been published for emission angles 50.2For such emission angles, the MED is less than the product of the IMFP and the cosine of the INTERNATIONAL STANDARD I
30、SO 13424:2013(E) ISO 2013 All rights reserved 1BS ISO 13424:2013ISO 13424:2013(E)emission angle by an amount that depends on the strength of the elastic scattering of the photoelectrons in the film.2Both the IMFP and the strength versus depend on the chemical composition of the film. The MED is typi
31、cally less than 5 nm for many materials and common XPS instruments and measurement conditions. If the effects of elastic scattering are neglected, the MED is given approximately by the product of the IMFP and the cosine of the emission angle. The latter estimates of the MED can be sufficient for emi
32、ssion angles larger than 50 although better estimates can be obtained, e.g. from the database.1If the total film thickness is greater than three times the largest MED, XPS can be used under certain conditions (see Annex D) together with ion sputtering to determine the variation of chemical compositi
33、on with depth.Table 1 provides a summary of the XPS methods which can be used for determining chemical composition and/or film thickness. Some methods can be utilized for the characterization of single-layer or multiple-layer thin films on a substrate and some methods can be used to determine the co
34、mposition-depth profile of a sample for which the composition is a function of depth measured from the surface (i.e. where there is not necessarily an interface between two or more phases). The choice of method typically depends on the type of sample and the analysts knowledge of the likely or expec
35、ted morphology of the sample (i.e. whether the sample can consist of a single overlayer film on a flat substrate, multiple films on a flat substrate, or a sample with composition varying continuously with depth), whether the total film thickness is less than or greater than the largest MED for the d
36、etected photoelectrons, and the desired information (i.e. film composition or film thickness). The first three methods in Table 1 are non-destructive while the final method is destructive (i.e. the composition of the exposed surface is determined by XPS as the sample is etched by ion bombardment). B
37、rief descriptions of these methods are given in the following clauses and additional information is provided in the indicated annexes.Table 1 XPS methods for the characterization of thin films on substrates and for samples with composition varying with depthClause MethodSample morphologyFilm thickne
38、ss less than three times MED?Information obtainedAdditional information5.2 General XPSSingle and multiple films on a flat substrateYesLayer order, film thickness, and film compositionAnnex A5.3Angle-resolved XPSMultiple films on a flat substrateSample with com-position varying with depthYesFilm thic
39、kness and film compositionComposition as a function of depthAnnex B5.4Peak-shape analysisMultiple films on a flat substrateSample with com-position varying with depthYesFilm thickness and film compositionComposition as a function of depthAnnex C5.5Variable pho-ton energy XPSMultiple films on a flat
40、substrateSample with com-position varying with depthNoFilm thickness and film compositionComposition as a function of depth5.6XPS with sputter-depth profilingMultiple films on a flat substrateSample with com-position varying with depthNoFilm thickness and film compositionComposition as a function of
41、 depthAnnex D2 ISO 2013 All rights reservedBS ISO 13424:2013ISO 13424:2013(E)XPS is typically performed with laboratory instruments that are often equipped with monochromated Al K or non-monochromated Al or Mg K X-ray sources. For some applications, XPS with X-rays from synchrotron-radiation sources
42、 is valuable because the energy of the X-ray exciting the sample can be varied. XPS with Ag X-rays is also used to observe deeper regions compared to excitation with Al X-rays. In some cases, X-ray energies less than the Mg or Al K X-ray energies can be selected to gain enhanced surface sensitivity
43、while in other cases, higher energies are chosen to gain greater bulk sensitivity and to avoid artefacts associated with the use of sputter-depth profiling.Analysts should be aware of possible artefacts in XPS analyses. These artefacts include sample degradation during X-ray irradiation, reactions o
44、f the sample with gases in the ambient vacuum, and many effects that can occur during sputtering-depth profiling.35.2 General XPSFor a uniform thin film on a flat substrate, the film thickness can be determined from a ratio of a photoelectron peak intensity of an element in the substrate for a parti
45、cular emission angle when an overlayer film is present to the corresponding intensity when the film is absent. Alternatively, the thickness can be obtained from a ratio of photoelectron peak intensity for an element in the film to the corresponding intensity for a thick film (i.e. a film with a thic
46、kness much greater than three times the MED). The composition of the film can be determined by the RSF method. Additional information is in Annex A.For multiple thin-film analysis, it is important to determine the relative order of the layers above the substrate. We can estimate the layer order, thi
47、cknesses, and compositions by measuring the changes of peak-intensity ratios of components at two widely separated emission angles. Further details are in Annex A.5.3 Angle-resolved XPSAngle-resolved XPS (ARXPS)4can be utilized to determine composition as a function of depth for depths up to three t
48、imes the largest MED of the detected electrons. The composition can be found for each film of a multilayer film on a substrate or the distribution of composition with depth can be determined for samples with no phase boundaries. For the former type of sample, film thicknesses can be estimated. Furth
49、er details are in Annex B.5.4 Peak-shape analysisPeak-shape analysis,5the analysis of a photoelectron peak and its associated region of inelastically scattered electrons, can be utilized to determine composition as a function of depth for depths up to three times the largest MED of the detected electrons. The analyst can know the expected morphology of the sample (i.e. the distribution of composition with depth) or can often deduce the likely morphology from peak-shape analysis. Further details are in Annex C.5.5 Variabl
