Surface chemical analysis — X-ray photoelectron spectroscopy — Guidelines for analysis

This document is intended to aid the operators of X-ray photoelectron spectrometers in their analysis of typical samples. It takes the operator through the analysis from the handling of the sample and the calibration and setting-up of the spectrometer to the acquisition of wide and narrow scans and also gives advice on quantification and on preparation of the final report.

Analyse chimique des surfaces — Spectroscopie de photoélectrons par rayons X — Lignes directrices pour l'analyse

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Published
Publication Date
21-Aug-2019
Current Stage
6060 - International Standard published
Due Date
12-Jul-2019
Completion Date
22-Aug-2019
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INTERNATIONAL ISO
STANDARD 10810
Second edition
2019-08
Surface chemical analysis — X-ray
photoelectron spectroscopy —
Guidelines for analysis
Analyse chimique des surfaces — Spectroscopie de photoélectrons par
rayons X — Lignes directrices pour l'analyse
Reference number
ISO 10810:2019(E)
©
ISO 2019

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ISO 10810:2019(E)

COPYRIGHT PROTECTED DOCUMENT
© ISO 2019
All rights reserved. Unless otherwise specified, or required in the context of its implementation, no part of this publication may
be reproduced or utilized otherwise in any form or by any means, electronic or mechanical, including photocopying, or posting
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ii © ISO 2019 – All rights reserved

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ISO 10810:2019(E)

Contents Page
Foreword .v
Introduction .vi
1 Scope . 1
2 Normative references . 1
3 Terms and definitions . 1
4 Symbols and abbreviations . 1
5 Overview of sample analysis . 2
6 Specimen characterization . 4
6.1 General . 4
6.2 Specimen forms . 5
6.2.1 General. 5
6.2.2 Single crystal . 5
6.2.3 Adsorbed or segregated layers, films and residues . 5
6.2.4 Interfaces and multilayered samples . 6
6.2.5 Non-porous . 6
6.2.6 Porous . 6
6.2.7 Powder . . 6
6.2.8 Fibres and textiles . 6
6.2.9 Internal interface . 6
6.3 Material types . 6
6.3.1 General. 6
6.3.2 Metals and alloys . 6
6.3.3 Polymers . 7
6.3.4 Semiconductors . 7
6.3.5 Magnetic materials . 7
6.3.6 Ceramics . 7
6.3.7 Catalysts . 7
6.3.8 Glass and insulators . 7
6.3.9 Biological . 7
6.3.10 Nanoparticles . 7
6.4 Handling and mounting of specimens . 7
6.5 Specimen treatments . 8
6.5.1 General. 8
6.5.2 Heating and cooling . 8
6.5.3 Scraping and fracture . . 8
6.5.4 Ion bombardment for analysing thin films . 8
6.5.5 Exposure to gases and liquids . 8
[8]
7 Instrument characterization . 8
7.1 General . 8
7.2 Instrument checks . 9
[9]
7.2.1 System health check . 9
7.2.2 Mechanical . 9
7.2.3 Sample holder . 9
7.2.4 Vacuum . 9
7.3 Instrument calibration .10
7.3.1 Calibration of binding energy scale .10
7.3.2 Intensity repeatability and intensity/energy response function (IERF).11
7.3.3 Linearity of intensity scale test .12
7.3.4 Lateral resolution .13
[21][22]
7.3.5 Depth resolution .13
7.3.6 Charge correction .16
7.4 Instrument set-up.16
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ISO 10810:2019(E)

7.4.1 Optimum settings .16
7.4.2 System configuration .17
8 The wide-scan spectrum .17
8.1 Data acquisition .17
8.1.1 General.17
8.1.2 Sample loading .18
8.1.3 Energy resolution .18
8.1.4 Energy range, step size and acquisition mode .18
8.1.5 X-ray source and conditions .18
8.1.6 Charge correction .19
8.1.7 Spectrum acquisition .19
8.1.8 X-ray degradation .19
8.1.9 Thin surface layer .19
8.2 Data analysis .19
8.2.1 Calibration of the binding energy scale .19
8.2.2 Peak table .20
8.2.3 Quantification .20
8.2.4 Assessment of the composition employing the Tougaard extrinsic
[42]
background  .21
8.2.5 Requirement for narrow scans .21
9 The narrow scan .21
9.1 General .21
9.2 Data acquisition .21
9.2.1 Instrument settings .21
9.2.2 Choice of region .21
9.3 Data analysis .22
9.3.1 Element identification .22
9.3.2 Chemical-state identification .22
9.3.3 Quantification .23
10 Test report .26
Bibliography .28
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ISO 10810:2019(E)

Foreword
ISO (the International Organization for 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 right 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 procedures 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 rules 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 identified 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 explanation of the voluntary nature of standards, the meaning of ISO specific terms and
expressions related to conformity assessment, as well as information about ISO's adherence to the
World Trade Organization (WTO) principles in the Technical Barriers to Trade (TBT) see www .iso
.org/iso/foreword .html.
This document was prepared by Technical Committee ISO/TC 201, Surface chemical analysis,
Subcommittee SC 7, Electron spectroscopies.
This second edition cancels and replaces the first edition (ISO 10810:2010), which has been technically
revised. The main changes to the previous edition are as follows:
— Table 3: semiconductor wafer added as a specimen form;
— 6.2.7: paragraph replaced to reflect modern practice;
— 6.3.10: nanoparticles added as a material type;
— Clause 8 and the flow chart in Figure 6 have been thoroughly revised to improve clarity. The cells in
the flow chart now contain references to the appropriate subclause within Clause 8;
— 8.2.1: it is now pointed out that the use of the C 1s peak provides only an approximate binding
energy reference;
— 9.3.3.3: mention has been made of the use of ionised clusters of inert gas atoms for depth profiling.
Any feedback or questions on this document should be directed to the user’s national standards body. A
complete listing of these bodies can be found at www .iso .org/members .html.
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ISO 10810:2019(E)

Introduction
X-ray photoelectron spectroscopy (XPS) is used extensively for the surface (1 nm to 10 nm) analysis
of materials. Elements in the sample (with the exception of hydrogen and helium) are identified from
comparisons of the measured binding energies of their core levels with tabulations of those energies
for the different elements. Their chemical states may be determined from shifts in peak positions and
other parameters compared with the data for that element in its pure elemental state. Information on
the quantities of such elements can be derived from the measured intensities of photoelectron peaks.
Calculation of the quantities of the constituent chemical species present in the surface layer studied
(outer 1 nm to 10 nm) may then be made using formulae and relative-sensitivity factors provided by the
spectrometer manufacturer or locally measured relative-sensitivity factors and appropriate software.
This guidance document is intended to aid the operators of X-ray photoelectron spectrometers in their
analysis of the surfaces (outer 1 nm to 10 nm) of typical samples.
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INTERNATIONAL STANDARD ISO 10810:2019(E)
Surface chemical analysis — X-ray photoelectron
spectroscopy — Guidelines for analysis
1 Scope
This document is intended to aid the operators of X-ray photoelectron spectrometers in their analysis
of typical samples. It takes the operator through the analysis from the handling of the sample and the
calibration and setting-up of the spectrometer to the acquisition of wide and narrow scans and also
gives advice on quantification and on preparation of the final report.
2 Normative references
The following documents are referred to in the text in such a way that some or all of their content
constitutes requirements of this document. 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, Surface chemical analysis — Vocabulary — Part 1: General terms and terms used in
spectroscopy
3 Terms and definitions
For the purposes of this document, the terms and definitions given in ISO 18115-1 apply.
ISO and IEC maintain terminological databases for use in standardization at the following addresses:
— ISO Online browsing platform: available at https: //www .iso .org/obp
— IEC Electropedia: available at http: //www .electropedia .org/
4 Symbols and abbreviations
AES Auger electron spectroscopy
ARXPS angle-resolved X-ray photoelectron spectroscopy
CCQM consultative committee for amount of substance
CRM certified reference material
EAL effective attenuation length
FAT fixed analyser transmission
FRR fixed retard ratio
FWHM full width at half maximum
IERF intensity/energy response function
NIST National Institute of Standards and Technology
NPL National Physical Laboratory
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ISO 10810:2019(E)

RM reference material
S/N signal-to-noise ratio
XPS X-ray photoelectron spectroscopy
Δ difference between the measured and reference energies for Au 4f
Au 7/2
Δ difference between the measured and reference energies for Cu 2p
Cu 3/2
5 Overview of sample analysis
Figure 1 is a flow chart illustrating the analysis of a typical sample by XPS. A preliminary consultation
with the supplier of the sample should be used to ensure that the sample is supplied in the form most
[2]
appropriate for analysis. ISO 18117 explains the issues involved with prior handling by the supplier
and also gives information on the most suitable container for transportation. In this consideration, the
analyst should also identify any particular problems likely to arise. Table 1 provides a list of example
problems. Prior to any work, discussions should be held between the analyst and the customer to
gain as much information as possible by reviewing what is already known regarding the sample and
[2]
its history. In addition to the information listed in ISO 18117 , Table 2 indicates information that
will assist in deciding how to conduct the XPS analysis. Following these preliminary discussions,
the sample(s) may need to be prepared to allow mounting in the spectrometer and to reduce, where
[1]
possible, the subsequent analysis time. ISO 18116 provides details of how to do this. The analyst
will be responsible for the instrument characterization, which will include the calibration state and
the overall performance of the XPS instrument. A guide to calibration of the energy scale is given in
[14] [9] [18]
ISO 15472 . Checks for the intensity scale are given in ISO 24237 and ISO 21270 .
Once the specimen has been mounted in the spectrometer and the system pumped down, data
acquisition can commence. A wide scan should be obtained first and then analysed to determine the
[31]
elements present. ISO 16243 provides information on recording and reporting data in XPS. The wide-
scan spectrum can provide qualitative and semiquantitative information regarding composition and
the depth distribution of species. This may yield sufficient information to satisfy the customer and the
analysis may be terminated. However, in most cases, more data are required and narrow-scan spectra
will then be recorded from regions identified in the wide-scan spectrum. Analysis of these narrow-
scan spectra will provide chemical-state information, more accurate quantitative information and
near-surface depth information. At a later time in the investigation the wide scan should be repeated
to determine if there has been degradation (e.g. due to X-ray irradiation or to surface reactions with
ambient gases in the vacuum system). Following evaluation of the XPS data, the analyst should produce
a report.
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ISO 10810:2019(E)

Table 1 — Problems likely to arise and related ISO standards
Problem Example ISO standard
[1]
Outgassing Water vapour ISO 18116
Degradation Polymers and organics ISO 18554
[28]
Charging Insulators ISO 19318
Reduction Oxides
Contaminant mobility Chlorine
[1]
Sample containment Powders ISO 18116
Surface topography Fibres
Table 2 — Sample information and history
Sample information and history
Thermal
Contamination
Possible composition
Segregation
Surface layer
Homogeneous
Islands
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ISO 10810:2019(E)

NOTE The numbers in brackets indicate the respective subclauses in this document.
Figure 1 — Flow chart of an XPS analysis
6 Specimen characterization
6.1 General
The complexity of the interacting factors in XPS analyses arises from the many different forms of
specimen materials and the variety of material types that may be encountered as well as from the
different XPS experiments that might be required. Table 3 illustrates possible specimen forms, material
types, and XPS experiments or issues for further review. The analyst should also be aware that samples
can consist of multiple components and phases, and that identification of the components and phases
present (and their spatial arrangements) can be an important part of an XPS analysis. A further
complication is that non-conducting samples may charge.
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ISO 10810:2019(E)

Table 3 — Some specimen forms, material types, in situ specimen treatments
and possible XPS experiments
Specimen forms Material types In situ specimen treatments XPS experiments
Adsorbed layers (6.2.3) Alloy (6.3.2) Cooling (6.5.2) Angle-resolved XPS
Amorphous Biological (6.3.9) Degradation Small area analysis
Fibres (6.2.8) Catalyst (6.3.7) Deposit thin films Large area analysis
Films (6.2.3) Ceramic (6.3.6) Expose to high gas pressure Depth profile
(6.5.5)
Interface (6.2.4) Composite Fracture (6.5.3) Imaging
Internal interface (6.2.9) Glass (6.3.8) Heating (6.5.2) Line scan
Liquid Insulator (6.3.8) Insert into liquids (6.5.5)
Multilayered (6.2.4) Magnetic metal (6.3.5) Ion bombardment (6.5.4)
Nano-material Metal (6.3.2) Scraping (6.5.3)
Non-metal (pure)
Non-porous (6.2.5) element
Pattern system Polymer (6.3.3)
Polycrystal Semiconductor (6.3.4)
Porous (6.2.6)
Powder (6.2.7)
Residue (6.2.3)
Segregated layer (6.2.3)
Single crystal (6.2.2)
Solid
Semiconductor wafer Semiconductor Ozone and UV/ozone cleaning
Textile (6.2.8)
Contamination
6.2 Specimen forms
6.2.1 General
The form of the specimen to be analysed will strongly dictate the kinds of experimental approach that
can and need to be employed.
6.2.2 Single crystal
This type of sample should have a flat surface. Quantitative analyses will generally be difficult because
of anisotropies in the angular distributions of the photoemitted electrons due to electron diffraction
[3][4]
or to forward-focusing effects . These anisotropies are nevertheless useful in determining the
structural properties of the sample.
6.2.3 Adsorbed or segregated layers, films and residues
It should, in general, be possible to obtain a quantitative analysis and chemical-state information for
[5][6]
adsorbed or segregated layers, films and residues . If the substrate is a single crystal, however,
quantitative analyses will generally be difficult, but the angular distributions of the photoemitted
[3]
electrons can give useful structural information . Angle-resolved XPS (ARXPS), as described in 9.3.3,
will enable the layer thickness to be determined, provided the layer thickness does not exceed around
three times the effective attenuation length (EAL) of the substrate peak. This will be of progressively
lower accuracy for films above one EAL in thickness.
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ISO 10810:2019(E)

6.2.4 Interfaces and multilayered samples
...

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