ISO 17109:2022
(Main)Surface chemical analysis — Depth profiling — Method for sputter rate determination in X-ray photoelectron spectroscopy, Auger electron spectroscopy and secondary-ion mass spectrometry sputter depth profiling using single and multi-layer thin films
Surface chemical analysis — Depth profiling — Method for sputter rate determination in X-ray photoelectron spectroscopy, Auger electron spectroscopy and secondary-ion mass spectrometry sputter depth profiling using single and multi-layer thin films
This document specifies a method for the calibration of the sputtered depth of a material from a measurement of its sputtering rate under set sputtering conditions using a single- or multi-layer reference sample with layers of the same material as that requiring depth calibration. The method has a typical accuracy in the range of 5 % to 10 % for layers 20 nm to 200 nm thick when sputter depth profiled using AES, XPS and SIMS. The sputtering rate is determined from the layer thickness and the sputtering time between relevant interfaces in the reference sample and this is used with the sputtering time to give the thickness of the sample to be measured. The determined ion sputtering rate can be used for the prediction of ion sputtering rates for a wide range of other materials so that depth scales and sputtering times in those materials can be estimated through tabulated values of sputtering yields and atomic densities.
Analyse chimique des surfaces — Profilage d'épaisseur — Méthode pour la détermination de la vitesse de pulvérisation lors du profilage d'épaisseur par pulvérisation en spectroscopie de photoélectrons par rayons X, spectroscopie d'électrons Auger et spectrométrie de masse des ions secondaires à l'aide de films minces multicouches
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INTERNATIONAL ISO
STANDARD 17109
Second edition
2022-03
Surface chemical analysis — Depth
profiling — Method for sputter rate
determination in X-ray photoelectron
spectroscopy, Auger electron
spectroscopy and secondary-ion mass
spectrometry sputter depth profiling
using single and multi-layer thin films
Analyse chimique des surfaces — Profilage d'épaisseur — Méthode
pour la détermination de la vitesse de pulvérisation lors du profilage
d'épaisseur par pulvérisation en spectroscopie de photoélectrons par
rayons X, spectroscopie d'électrons Auger et spectrométrie de masse
des ions secondaires à l'aide de films minces multicouches
Reference number
ISO 17109:2022(E)
© ISO 2022
---------------------- Page: 1 ----------------------
ISO 17109:2022(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2022
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 on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2022 – All rights reserved
---------------------- Page: 2 ----------------------
ISO 17109:2022(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms . 2
4 Requirement of single- and multi-layer reference thin films . 2
5 Determination of sputtering rate . 3
Annex A (informative) Interlaboratory test report . 9
Annex B (informative) Prediction of the rates for a wide range of other materials through
tabulated values of sputtering yields .20
Bibliography .21
iii
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---------------------- Page: 3 ----------------------
ISO 17109:2022(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 4, Depth profiling.
This second edition cancels and replaces the first edition (ISO 17109:2015), which has been technically
revised.
The main changes are as follows:
— in 4.5, reference documents for a cleaning of thin film surface have been added;
— the flowchart in Clause 5 has been revised to improve clarity.
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.
iv
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---------------------- Page: 4 ----------------------
ISO 17109:2022(E)
Introduction
The sputtering rate in surface chemical analysis is generally determined from the quotient of sputtered
depth, measured using stylus profilometry, and sputtering time. However, for multi-layered thin films,
only the average sputtering rate is determined by this method. Therefore, this method is difficult to
apply to multi-layered thin films comprised of materials with different sputtering rates. Sputtering
rates are also affected by various experimental parameters so that it is difficult for them to tabulate and
to be used for sputter depth calibrations. For higher accuracies, it is important for sputtering rates to be
determined under specific experimental conditions for each laboratory for sputter depth calibration.
Sputter rates should be determined using single-layers that are much thicker than the projected range
of the sputtering ions so that the surface transient effect is negligible or by using multi-layered thin
films where the effect of surface transient phenomena can be excluded, and interface transients can be
minimized.
This document is developed for the calibration of sputtered depth by determining the ion sputtering
rate for depth profiling measurement with Auger electron spectroscopy (AES), X-ray photoelectron
spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) using single- and multi-layer thin
films. The measured ion sputtering rate can be used for the prediction of ion sputtering rates for a
wide range of other materials so that depth scales or sputtering times can be estimated in day-to-day
samples through tabulated values of sputtering yields and bulk densities.
v
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---------------------- Page: 5 ----------------------
INTERNATIONAL STANDARD ISO 17109:2022(E)
Surface chemical analysis — Depth profiling — Method
for sputter rate determination in X-ray photoelectron
spectroscopy, Auger electron spectroscopy and secondary-
ion mass spectrometry sputter depth profiling using single
and multi-layer thin films
1 Scope
This document specifies a method for the calibration of the sputtered depth of a material from a
measurement of its sputtering rate under set sputtering conditions using a single- or multi-layer
reference sample with layers of the same material as that requiring depth calibration. The method
has a typical accuracy in the range of 5 % to 10 % for layers 20 nm to 200 nm thick when sputter
depth profiled using AES, XPS and SIMS. The sputtering rate is determined from the layer thickness
and the sputtering time between relevant interfaces in the reference sample and this is used with the
sputtering time to give the thickness of the sample to be measured. The determined ion sputtering rate
can be used for the prediction of ion sputtering rates for a wide range of other materials so that depth
scales and sputtering times in those materials can be estimated through tabulated values of sputtering
yields and atomic densities.
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 14606, Surface chemical analysis — Sputter depth profiling — Optimization using layered systems as
reference materials
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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 https:// www .electropedia .org/
3.1.1
upper plateau
region exhibiting intensities higher than 95 % of the maximum intensity of the characteristic signal for
that layer and covering more than half the thickness of that layer
3.1.2
lower plateau
region exhibiting intensities lower than the minimum intensity plus 5 % of the maximum intensity of
the characteristic signal for that layer and covering more than half the thickness of that layer
1
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ISO 17109:2022(E)
3.2 Symbols and abbreviated terms
For the purposes of this document, the following symbols and abbreviated terms apply.
SD standard deviation
I
50 % signal intensity of sputter depth profile
50
I
average intensity in the upper plateau region of the depth profile
U
I
average intensity in the lower plateau region of the depth profile
L
z
sputtering rate of layer A
A
z
sputtering rate of layer B
B
R
thickness of layer A of a single- or multi-layer reference thin film
d
A
R
thickness of layer B of a multi-layer reference thin film
d
B
R
sputtering time of layer A of a single- or multi-layer reference thin film
t
A
R
sputtering time of layer B of a multi-layer reference thin film
t
B
z
average sputtering rate of layer A
A
z
average sputtering rate of layer B
B
U
thickness of layer A in a single- or multi-layered thin film to be measured
d
A
U
thickness of layer B in a multi-layered thin film to be measured
d
B
U
average sputtering time from three consecutive sputter depth profiles of the layer A in a
t
A
multi-layered thin film to be measured
U
average sputtering time from three consecutive sputter depth profiles of the layer B in a
t
B
multi-layered thin film to be measured
U
sputtering time of layer A in a multi-layered thin film to be measured
t
A
U
sputtering time of layer B in a multi-layered thin film to be measured
t
B
U
uncertainty of the thickness of the layer A
Δ d
()
A
U U
σ t standard deviation of t
()
A A
σ z standard deviation of z
()
A A
4 Requirement of single- and multi-layer reference thin films
4.1 The thickness of each layer in multi-layer thin films and the thickness of single-layer thin
films shall be sufficiently thicker than the sum of the projected range of the sputtering ions and the
information depth of the analytical method, so that an upper plateau and a lower plateau shall be
obtained for each layer in sputter depth profiling. The projected range can be simply calculated using
[1]
SRIM code which is available from http:// www .srim .org .
NOTE Sample rotation during ion sputtering is shown to reduce surface roughness development especially
[2]
of polycrystalline films leading to sharper interfaces and a better estimate of sputtering rates.
2
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ISO 17109:2022(E)
4.2 The surface and the interfaces shall be flat and parallel to each other to avoid any distortion of
sputter depth profiles. The surface roughness is often measured using atomic force microscopy and the
thickness variation using transmission electron microscopy. The surface roughness of sample and the
thickness variation of each layer shall be smaller than the sum of the projected range of the sputtering
ions and the information depth of the analytical method.
4.3 The thickness of each layer in multi-layer thin films and the thickness of single-layer thin films
shall be determined by high resolution cross-sectional transmission electron microscopy, grazing
incidence X-ray reflectivity, medium energy ion scattering spectroscopy, or other appropriate methods
[3],[4]
for which an accurate uncertainty of measurement can be evaluated using relevant references .
4.4 The number of A/B layer pairs in the multi-layered reference thin films shall be greater than two
since profiles of the first layer A and the last layer B shall not be used due to the surface and the final
interface transient effects.
4.5 For single-layer thin films, to minimize any likely contamination or surface oxidation problems,
materials like SiO on Si and Ta O on Ta which are stable and remain clean or can easily be cleaned
2 2 5
[5]
are recommended. Guidelines on how to clean thin film surface are available from ISO 18116 and
[6]
ISO 18117 .
5 Determination of sputtering rate
5.1 Set the sputtering conditions to be those for which the sputtering rates are required. Changes
in the sputtering species, the impact energy, and beam current will change the sputtering rates. The
sputter depth profiling parameters are optimized according to ISO 14606.
NOTE 1 A typical measurement procedure and result of depth profiling measurement with AES, XPS, and SIMS
using multi-layered thin films are illustrated in Annex A.
NOTE 2 The ordinate axis units can be intensity, atomic fraction, an intensity ratio, concentration, or whatever
is the unit most linearly related to the amount of substance present at each depth.
5.2 The sputter depth profiles shall be measured after the instrument has stabilized to minimize
uncertainty due to instrumental fluctuation. Inspect the data, identify, and then ignore, in what follows,
any noise spikes.
5.3 Measure the sputter depth profile of a single- or multi-layer reference thin film and determine
the interface position by the point where the signal intensity of the element reaches 50 % of its value
between the lower plateau where the element is essentially absent or of lower concentration and the
upper plateau level for the layer where it is present with higher concentration present. The determination
of the interface position by this procedure is applied to this document until the development of an ISO
Standard for interface position. The average intensity in the upper plateau region is the plateau intensity
(I ). This shall be calculated by summing the intensity for each measurement where the intensity is
U
greater than 95 % of the maximum intensity and dividing by the number of measurements used in the
summation.
A similar procedure shall be adopted for the determination of the lower plateau for each constituent of
the profile (I ). The average intensity shall be calculated as follows:
L
a) subtract the minimum intensity value in this part of the profile from all readings;
b) calculate the value of 5 % of the maximum intensity [following the subtraction in a)];
c) sum all of the intensities which are less than the 5 % value calculated in b);
d) divide the sum by the number of readings to get an average;
e) add the minimum intensity to the average calculated in d) to arrive at I .
L
3
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ISO 17109:2022(E)
The 50 % signal intensity shall be calculated using Formula (1):
II=−()I /2 (1)
50 UL
where
I is the 50 % signal intensity of sputter depth profile, in per cent;
50
I is the average intensity in the upper plateau region of the depth profile;
U
I is the average intensity in the lower plateau region of the depth profile.
L
Examples of determining the upper plateau level and the lower plateau level are demonstrated in
Figure A.2 to Figure A.4 for AES, XPS, and SIMS depth profiling, respectively. For single-layer thin
films, the beginning of the sputter time is defined by the time where the intensity for the given element
reaches 50 % of the upper plateau level in the similar manner.
For some sputter depth profiling, often by SIMS, the interface positions may be significantly affected by
changes in the matrix effect in the interface region. If the upper plateau defined with intensities higher
than 95 % of the maximum intensity is less than half of the layer thickness due to large distortions at
interfaces, this document shall not be used for sputter rate determination.
[7]
NOTE 1 The 50 % of the plateau level is mentioned in ISO/TR 15969 .
NOTE 2 A flow chart is given to guide the sputter rate determination of multi-layered thin films and single-
layer thin films as below.
5.4 The sputtering rates of layers of A, z , and B, z , are determined by dividing the thicknesses of
A B
R R R R
layer A, d , and B, d , by the sputtering times of layers of A, t , and B, t , of a reference A/B/A/B….
A B A B
multi-layer thin film, using Formulae (2) and (3). The unit of sputtering rate is nm/s.
R
d
A
z = (2)
A
R
t
A
R
d
B
z = (3)
B
R
t
B
where
z is the sputtering rate of layer A;
A
z is the sputtering rate of layer B;
B
R
is the thickness of layer A of a single- or multi-layer reference thin film;
d
A
R
is the thickness of layer B of a single- or multi-layer reference thin film;
d
B
R
is the sputtering time of layer A of a single- or multi-layer reference thin film;
t
A
R
is the sputtering time of layer B of a single- or multi-layer reference thin film.
t
A
R
The sputtering time of layers of A, t , is determined from the time interval from B/A to A/B interfaces
A
R
and that of layers of B, t , is determined from the time period from A/B to B/A interfaces. Measure
B
three sputter depth profiles to determine the uncertainties. If the standard deviation (SD) is
inappropriate, the sputter depth profiling parameters shall be optimized according to ISO 14606 to
improve the uncertainties.
4
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ISO 17109:2022(E)
The average sputtering rates of layers of A, z , and B, z , are determined from the average values of
A B
the respective sputtering rates z and z of all layers except the outmost layer A and the last layer B
A B
adjacent to the substrate.
For single-layer thin films, the sputtering rates of layer A, z , is determined with Formula (2). The
A
R
sputtering time of layer A, t , is determined from the time interval from the surface layer A to the A/
A
substrate interface. The average sputtering rate of layer A, z , is determined from the average value of
A
three consecutive profiling of a single-layer thin film.
NOTE SD of better than 5 % has been found useful and practicable.
5
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ISO 17109:2022(E)
Figure 1 — Determination of sputtering rate
5.5 For the multi-layered reference thin film, estimate the standard deviation of sputtering rates for
layer A and layer B using the three average sputtering rates of layers of A, z , and B, z , from three
A B
6
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ISO 17109:2022(E)
consecutive sputter depth profiles. For single-layered thin films, the standard deviation of sputtering
rate is calculated from three consecutive sputter depth profiles of a single-layered thin film.
5.6 If the measured standard deviation in the sputter rates is greater than 5 %, then the experimental
parameters shall be adjusted and the depth profile measurements repeated. The standard deviation
of sputter rates from each layer can be used for evaluating the constancy of the sputtering rate as a
function of depth or of the time that the gun has been running. Additionally, the change of the sputter
rates from each layer excluding the first A layer and the last B layer can be used for evaluation of both
the short- and long-term drifts of the ion bea
...
FINAL
INTERNATIONAL ISO/FDIS
DRAFT
STANDARD 17109
ISO/TC 201/SC 4
Surface chemical analysis — Depth
Secretariat: JISC
profiling — Method for sputter rate
Voting begins on:
2021-12-08 determination in X-ray photoelectron
spectroscopy, Auger electron
Voting terminates on:
2022-02-02
spectroscopy and secondary-ion mass
spectrometry sputter depth profiling
using single and multi-layer thin films
Analyse chimique des surfaces — Profilage d'épaisseur — Méthode
pour la détermination de la vitesse de pulvérisation lors du profilage
d'épaisseur par pulvérisation en spectroscopie de photoélectrons par
rayons X, spectroscopie d'électrons Auger et spectrométrie de masse
des ions secondaires à l'aide de films minces multicouches
RECIPIENTS OF THIS DRAFT ARE INVITED TO
SUBMIT, WITH THEIR COMMENTS, NOTIFICATION
OF ANY RELEVANT PATENT RIGHTS OF WHICH
THEY ARE AWARE AND TO PROVIDE SUPPOR TING
DOCUMENTATION.
IN ADDITION TO THEIR EVALUATION AS
Reference number
BEING ACCEPTABLE FOR INDUSTRIAL, TECHNO-
ISO/FDIS 17109:2021(E)
LOGICAL, COMMERCIAL AND USER PURPOSES,
DRAFT INTERNATIONAL STANDARDS MAY ON
OCCASION HAVE TO BE CONSIDERED IN THE
LIGHT OF THEIR POTENTIAL TO BECOME STAN-
DARDS TO WHICH REFERENCE MAY BE MADE IN
NATIONAL REGULATIONS. © ISO 2021
---------------------- Page: 1 ----------------------
ISO/FDIS 17109:2021(E)
COPYRIGHT PROTECTED DOCUMENT
© ISO 2021
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 on
the internet or an intranet, without prior written permission. Permission can be requested from either ISO at the address below
or ISO’s member body in the country of the requester.
ISO copyright office
CP 401 • Ch. de Blandonnet 8
CH-1214 Vernier, Geneva
Phone: +41 22 749 01 11
Email: copyright@iso.org
Website: www.iso.org
Published in Switzerland
ii
© ISO 2021 – All rights reserved
---------------------- Page: 2 ----------------------
ISO/FDIS 17109:2021(E)
Contents Page
Foreword .iv
Introduction .v
1 Scope . 1
2 Normative references . 1
3 Terms, definitions, symbols and abbreviated terms . 1
3.1 Terms and definitions . 1
3.2 Symbols and abbreviated terms . 2
4 Requirement of single- and multi-layer reference thin films . 2
5 Determination of sputtering rate . 3
Annex A (informative) Interlaboratory test report . 9
Annex B (informative) Prediction of the rates for a wide range of other materials through
tabulated values of sputtering yields .20
Bibliography .21
iii
© ISO 2021 – All rights reserved
---------------------- Page: 3 ----------------------
ISO/FDIS 17109:2021(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 4, Depth profiling.
This second edition cancels and replaces the first edition (ISO 17109:2015), which has been technically
revised.
The main changes are as follows:
— in 4.5, reference documents for a cleaning of thin film surface have been added;
— the flowchart in Clause 5 has been revised to improve clarity.
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.
iv
© ISO 2021 – All rights reserved
---------------------- Page: 4 ----------------------
ISO/FDIS 17109:2021(E)
Introduction
The sputtering rate in surface chemical analysis is generally determined from the quotient of sputtered
depth, measured using stylus profilometry, and sputtering time. However, for multi-layered thin films,
only the average sputtering rate is determined by this method. Therefore, this method is difficult to
apply to multi-layered thin films comprised of materials with different sputtering rates. Sputtering
rates are also affected by various experimental parameters so that it is difficult for them to tabulate and
to be used for sputter depth calibrations. For higher accuracies, it is important for sputtering rates to be
determined under specific experimental conditions for each laboratory for sputter depth calibration.
Sputter rates should be determined using single-layers that are much thicker than the projected range
of the sputtering ions so that the surface transient effect is negligible or by using multi-layered thin
films where the effect of surface transient phenomena can be excluded, and interface transients can be
minimized.
This document is developed for the calibration of sputtered depth by determining the ion sputtering
rate for depth profiling measurement with Auger electron spectroscopy (AES), X-ray photoelectron
spectroscopy (XPS), and secondary ion mass spectrometry (SIMS) using single- and multi-layer thin
films. The measured ion sputtering rate can be used for the prediction of ion sputtering rates for a
wide range of other materials so that depth scales or sputtering times can be estimated in day-to-day
samples through tabulated values of sputtering yields and bulk densities.
v
© ISO 2021 – All rights reserved
---------------------- Page: 5 ----------------------
FINAL DRAFT INTERNATIONAL STANDARD ISO/FDIS 17109:2021(E)
Surface chemical analysis — Depth profiling — Method
for sputter rate determination in X-ray photoelectron
spectroscopy, Auger electron spectroscopy and secondary-
ion mass spectrometry sputter depth profiling using single
and multi-layer thin films
1 Scope
This document specifies a method for the calibration of the sputtered depth of a material from a
measurement of its sputtering rate under set sputtering conditions using a single- or multi-layer
reference sample with layers of the same material as that requiring depth calibration. The method
has a typical accuracy in the range of 5 % to 10 % for layers 20 nm to 200 nm thick when sputter
depth profiled using AES, XPS and SIMS. The sputtering rate is determined from the layer thickness
and the sputtering time between relevant interfaces in the reference sample and this is used with the
sputtering time to give the thickness of the sample to be measured. The determined ion sputtering rate
can be used for the prediction of ion sputtering rates for a wide range of other materials so that depth
scales and sputtering times in those materials can be estimated through tabulated values of sputtering
yields and atomic densities.
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 14606, Surface chemical analysis — Sputter depth profiling — Optimization using layered systems as
reference materials
3 Terms, definitions, symbols and abbreviated terms
3.1 Terms and definitions
For the purposes of this document, the following terms and definitions 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 https:// www .electropedia .org/
3.1.1
upper plateau
region exhibiting intensities higher than 95 % of the maximum intensity of the characteristic signal for
that layer and covering more than half the thickness of that layer
3.1.2
lower plateau
region exhibiting intensities lower than the minimum intensity plus 5 % of the maximum intensity of
the characteristic signal for that layer and covering more than half the thickness of that layer
1
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---------------------- Page: 6 ----------------------
ISO/FDIS 17109:2021(E)
3.2 Symbols and abbreviated terms
For the purposes of this document, the following symbols and abbreviated terms apply.
SD standard deviation
I
50 % signal intensity of sputter depth profile
50
I
average intensity in the upper plateau region of the depth profile
U
I
average intensity in the lower plateau region of the depth profile
L
z
sputtering rate of layer A
A
z
sputtering rate of layer B
B
R
thickness of layer A of a single- or multi-layer reference thin film
d
A
R
thickness of layer B of a multi-layer reference thin film
d
B
R
sputtering time of layer A of a single- or multi-layer reference thin film
t
A
R
sputtering time of layer B of a multi-layer reference thin film
t
B
z
average sputtering rate of layer A
A
z
average sputtering rate of layer B
B
U
thickness of layer A in a single- or multi-layered thin film to be measured
d
A
U
thickness of layer B in a multi-layered thin film to be measured
d
B
U
average sputtering time from three consecutive sputter depth profiles of the layer A in a
t
A
multi-layered thin film to be measured
U
average sputtering time from three consecutive sputter depth profiles of the layer B in a
t
B
multi-layered thin film to be measured
U
sputtering time of layer A in a multi-layered thin film to be measured
t
A
U
sputtering time of layer B in a multi-layered thin film to be measured
t
B
U
uncertainty of the thickness of the layer A
Δ d
()
A
U U
σ t standard deviation of t
()
A A
σ z standard deviation of z
()
A A
4 Requirement of single- and multi-layer reference thin films
4.1 The thickness of each layer in multi-layer thin films and the thickness of single-layer thin
films shall be sufficiently thicker than the sum of the projected range of the sputtering ions and the
information depth of the analytical method, so that an upper plateau and a lower plateau shall be
obtained for each layer in sputter depth profiling. The projected range can be simply calculated using
[1]
SRIM code which is available from http:// www .srim .org .
NOTE Sample rotation during ion sputtering is shown to reduce surface roughness development especially
[2]
of polycrystalline films leading to sharper interfaces and a better estimate of sputtering rates.
2
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ISO/FDIS 17109:2021(E)
4.2 The surface and the interfaces shall be flat and parallel to each other to avoid any distortion of
sputter depth profiles. The surface roughness is often measured using atomic force microscopy and the
thickness variation using transmission electron microscopy. The surface roughness of sample and the
thickness variation of each layer shall be smaller than the sum of the projected range of the sputtering
ions and the information depth of the analytical method.
4.3 The thickness of each layer in multi-layer thin films and the thickness of single-layer thin films
shall be determined by high resolution cross-sectional transmission electron microscopy, grazing
incidence X-ray reflectivity, medium energy ion scattering spectroscopy, or other appropriate methods
[3],[4]
for which an accurate uncertainty of measurement can be evaluated using relevant references .
4.4 The number of A/B layer pairs in the multi-layered reference thin films shall be greater than two
since profiles of the first layer A and the last layer B shall not be used due to the surface and the final
interface transient effects.
4.5 For single-layer thin films, to minimize any likely contamination or surface oxidation problems,
materials like SiO on Si and Ta O on Ta which are stable and remain clean or can easily be cleaned
2 2 5
[5]
are recommended. Guidelines on how to clean thin film surface are available from ISO 18116 and
[6]
ISO 18117 .
5 Determination of sputtering rate
5.1 Set the sputtering conditions to be those for which the sputtering rates are required. Changes
in the sputtering species, the impact energy, and beam current will change the sputtering rates. The
sputter depth profiling parameters are optimized according to ISO 14606.
NOTE 1 A typical measurement procedure and result of depth profiling measurement with AES, XPS, and SIMS
using multi-layered thin films are illustrated in Annex A.
NOTE 2 The ordinate axis units can be intensity, atomic fraction, an intensity ratio, concentration, or whatever
is the unit most linearly related to the amount of substance present at each depth.
5.2 The sputter depth profiles shall be measured after the instrument has stabilized to minimize
uncertainty due to instrumental fluctuation. Inspect the data, identify, and then ignore, in what follows,
any noise spikes.
5.3 Measure the sputter depth profile of a single- or multi-layer reference thin film and determine
the interface position by the point where the signal intensity of the element reaches 50 % of its value
between the lower plateau where the element is essentially absent or of lower concentration and the
upper plateau level for the layer where it is present with higher concentration present. The determination
of the interface position by this procedure is applied to this document until the development of an ISO
Standard for interface position. The average intensity in the upper plateau region is the plateau intensity
(I ). This shall be calculated by summing the intensity for each measurement where the intensity is
U
greater than 95 % of the maximum intensity and dividing by the number of measurements used in the
summation.
A similar procedure shall be adopted for the determination of the lower plateau for each constituent of
the profile (I ). The average intensity shall be calculated as follows:
L
a) subtract the minimum intensity value in this part of the profile from all readings;
b) calculate the value of 5 % of the maximum intensity [following the subtraction in a)];
c) sum all of the intensities which are less than the 5 % value calculated in b);
d) divide the sum by the number of readings to get an average;
e) add the minimum intensity to the average calculated in d) to arrive at I .
L
3
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ISO/FDIS 17109:2021(E)
The 50 % signal intensity shall be calculated using Formula (1):
II=−()I /2 (1)
50 UL
where
I is the 50 % signal intensity of sputter depth profile, in per cent;
50
I is the average intensity in the upper plateau region of the depth profile;
U
I is the average intensity in the lower plateau region of the depth profile.
L
Examples of determining the upper plateau level and the lower plateau level are demonstrated in
Figure A.2 to Figure A.4 for AES, XPS, and SIMS depth profiling, respectively. For single-layer thin
films, the beginning of the sputter time is defined by the time where the intensity for the given element
reaches 50 % of the upper plateau level in the similar manner.
For some sputter depth profiling, often by SIMS, the interface positions may be significantly affected by
changes in the matrix effect in the interface region. If the upper plateau defined with intensities higher
than 95 % of the maximum intensity is less than half of the layer thickness due to large distortions at
interfaces, this document shall not be used for sputter rate determination.
[7]
NOTE 1 The 50 % of the plateau level is mentioned in ISO/TR 15969 .
NOTE 2 A flow chart is given to guide the sputter rate determination of multi-layered thin films and single-
layer thin films as below.
5.4 The sputtering rates of layers of A, z , and B, z , are determined by dividing the thicknesses of
A B
R R R R
layer A, d , and B, d , by the sputtering times of layers of A, t , and B, t , of a reference A/B/A/B….
A B A B
multi-layer thin film, using Formulae (2) and (3). The unit of sputtering rate is nm/s.
R
d
A
z = (2)
A
R
t
A
R
d
B
z = (3)
B
R
t
B
where
z is the sputtering rate of layer A;
A
z is the sputtering rate of layer B;
B
R
is the thickness of layer A of a single- or multi-layer reference thin film;
d
A
R
is the thickness of layer B of a single- or multi-layer reference thin film;
d
B
R
is the sputtering time of layer A of a single- or multi-layer reference thin film;
t
A
R
is the sputtering time of layer B of a single- or multi-layer reference thin film.
t
A
R
The sputtering time of layers of A, t , is determined from the time interval from B/A to A/B interfaces
A
R
and that of layers of B, t , is determined from the time period from A/B to B/A interfaces. Measure
B
three sputter depth profiles to determine the uncertainties. If the standard deviation (SD) is
inappropriate, the sputter depth profiling parameters shall be optimized according to ISO 14606 to
improve the uncertainties.
4
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ISO/FDIS 17109:2021(E)
The average sputtering rates of layers of A, z , and B, z , are determined from the average values of
A B
the respective sputtering rates z and z of all layers except the outmost layer A and the last layer B
A B
adjacent to the substrate.
For single-layer thin films, the sputtering rates of layer A, z , is determined with Formula (2). The
A
R
sputtering time of layer A, t , is determined from the time interval from the surface layer A to the A/
A
substrate interface. The average sputtering rate of layer A, z , is determined from the average value of
A
three consecutive profiling of a single-layer thin film.
NOTE SD of better than 5 % has been found useful and practicable.
5
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ISO/FDIS 17109:2021(E)
Figure 1 — Determination of sputtering rate
5.5 For the multi-layered reference thin film, estimate the standard deviation of sputtering rates for
layer A and layer B using the three average sputtering rates of layers of A, z , and B, z , from three
A B
6
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ISO/FDIS 17109:2021(E)
consecutive sputter depth profiles. For single-layered thin films, the standard deviation of sputtering
rate is calculated from three consecutive sputter depth profiles of a single-layered thin film.
5.6 If the measured standard deviation in the sputter rates is greater than 5 %, then the experimental
parameters shall be adjusted and the depth profile measurements repeated. The standard deviation
of sputter rates from each layer can be used for evaluating the constanc
...
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