NBS

PUBLICATIONS Reference

NAT'L INST. OF STAND & TECH

AlllOb 0341.11

NBSIR 85-3120

The Coordinated Development of

Standards for Surface Chemical

Analysis

M. P. Seah

Division of Materials Applications

National Physical Laboratory

Teddington, Middlesex

TWII OLW

United Kingdom

and

C. J. Powell

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Surface Science Division

Gaithersburg, MD 20899

U.S. A.

March 1985

Prepared for: •QC

100

,U56

35-3120

1985

U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Gaithersburg, MD 20899

NATIONAL BUREAU

OF STANDARDS

LIBRARY NBSIR 85-3120

* THE COORDINATED DEVELOPMENT OF

STANDARDS FOR SURFACE CHEMICAL

ANALYSIS

M. P. Seah

Division of Materials Applications

National Physical Laboratory

Teddington, Middlesex

TWII OLW

United Kingdom

and

C. J. Powell

U S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Surface Science Division

Gaithersburg, MD 20899

USA.

March 1 985

Prepared for: U.S. DEPARTMENT OF COMMERCE

National Bureau of Standards

Gaithersburg, MD 20899

U.S. DEPARTMENT OF COMMERCE. Malcolm Baldrige, Secretary

NATIONAL BUREAU OF STANDARDS. Ernest Ambler. Director

ABSTRACT

This report is based on a proposal to the Steering Committee of the

Versailles Project on Advanced Materials and Standards (VAMAS) for the

coordinated development amongst the VAMAS member states of standards for

surface chemical analysis. VAMAS was established following the Economic

Summit meeting at Versailles, France in 1982 that agreed on a number of

projects relating to technology, growth, and employment. Specifically,

VAMAS was organized to promote international coordination in the development of standards in a wide range of advanced material sectors. Surface

chemical analysis was approved as a VAMAS Technical Working Area in June,

1984.

The report describes the growth and diversity of surface analysis in

the development of advanced materials in modern technologies and,

additionally, the use of surface analysis for improved films and coatings.

The principal techniques of surface analysis in common use are identified

and the technical limitations to accurate surface analyses identified.

Accurate surface analyses require: (i) knowledge of the principles of the

measurement method, (ii) knowledge of the behavior of the measuring

instrument, and (iii) correct interpretation and expression of the final

measured result. Standards for the measurement of surface composition

with known accuracy and for the reliable determination of chemical state

require: (a) a base of principles, definitions of terms, and suitable

equations, (b) reference procedures for the measurement of intensities and

spectral features, (c) procedures and data for instrument calibration: ,

(d) reference data for material parameters such as elemental sensitivity

i
factors, matrix terms, chemical state spectra, ion sputtering rates, etc;

and (e) standard methods for specifying an analysis. Specific needs are

identified for the common methods of surface analysis (Auger-electron

spectroscopy, x-ray photoelectron spectroscopy, and secondary-ion mass

spectroscopy) together with the needs for ion sputtering which is used to

obtain composition versus depth information in films and coatings.

Existing standards activities in the member countries of VAMAS are

reviewed and suggestions are made for additional standards for surface

chemical analysis.

Key words: reference data; reference materials; surface analysis; surface

standards; Versailles Project on Advanced Materials and

Standards
TABLE OF CONTENTS

Page

ABSTRACT i

1. The Versailles Project on Advanced Materials and

Standards (VAMAS) , 1

2. Significance of Surface Chemical Analysis 2

3. Objective of the VAMAS Surface Chemical Analysis

Working Party 3

4. Project Areas 4

(a) Auger Electron Spectroscopy 6

(b) X-Ray Photoelectron Spectroscopy 9

(c) Secondary Ion Mass Spectroscopy 10

(d) Ion Sputtering 12

5. Current Activities of a Standards, Measurement, or

Quantification Nature in Surface Chemical Analysis 13

(a) U.S.A 14

(b) Europe 15

(c) International Union of Pure and Applied Chemistry .... 16

6. .Initial Projects Proposed for Coordination Through VAMAS . . 16

7. Implementation 18

Appendix 1 . Round Robins Sponsored by ASTM Committees

E-42 on Surface Analysis and D-32 on Catalysts . . 21

Appendix 2. Standards and Recommended Practices Produced by

ASTM Committee E-42 on Surface Analysis

iii
Page

Appendix 3. Reference Data, Procedures, and Round Robins

Sponsored by the NPL-BCR Program 25

References 27

Table 1. Technical Representatives to the Surface Chemical

Analysis Working Party from the VAMAS Member States . 28

Figure Captions 30

iv
1. The Versailles Project on Advanced Materials and Standards (VAMAS)

As a result of the initiatives originating in the 1982 Economic

Summit meeting of Heads of State or Government at Versailles, there will

be increased international coordination in the development of standards in

a wide range of advanced materials sectors. This Economic Summit between

the Heads of State or Government of Canada, France, the Federal Republic

of Germany, Italy, Japan, the United Kingdom, and the United States of

America and the Representatives of the European Communities , nominated a

Working Group to report on the theme of collaborative projects relating to

"Technology, Growth and Employment.” Within this report, in the sector of

"Improvement of Living Conditions, Employment and Protection of the

Environment," we find the Versailles Project on Advanced Materials and

Standards, otherwise known as VAMAS. Further information on similar

Versailles projects has been published recently. 1

The Steering Committee of VAMAS, comprising representatives of all of

the Member States listed above, including the Commission of the European

Communities (CEC) , has already considered and approved the launch of a

small number of sector working parties with a further ten or so directly

under review. The intention of the scheme is to stimulate the

introduction of advanced materials into high technology products and

engineering structures with the overall aim of encouraging international

trade. This may be achieved through two routes: (i) by agreement between

national experts responsible for setting national codes of practice and

performance standards so that all such standards and codes are compat 1 bl <

and ISO standards are more easily established through the International

1
Organization for Standards; or (ii) through multilateral research aimed at

furnishing the enabling scientific and metrological base necessary to

achieve agreement on standards.

2. Significance of Surface Chemical Analysis

Increasingly today we see the introduction of sophisticated advanced

materials configurations entering everyday use in thin film or surface

layer form. This is integral to established technologies, such as

microelectronics , as well as growing in importance in fields such as

corrosion and catalysis. Coating technology, vacuum metallurgy, ion

implantation, and plasma processing are but some of the many

surface-science-related sectors which have acknowledged high growth

potential for manufacturing industry. The development of very novel

technologies in these areas depends on our ability to measure the chemical

state of the films we deposit or the surfaces we prepare. Again, the

reliability of these films or surfaces, and the assurances that we may

make about them, depend on our ability to measure and verify surface

compositions. The ubiquity of surface analysis through all sectors of

industry is illustrated in the pie diagram based on United Kingdom

manufacturing shown in Fig. 1; similar diversity has been documented in

the U.S.A. 2

The recognition of the importance of surfaces to technology may be

seen in the growing number of special projects and fund allocations in

this general area in the VAMAS Member States. The permeation of surface

2
analysis throughout the world is shown by the map in Fig. 2, although we

should note that all of the surface analysis instrument manufacturers and

about 90% of the research effort is concentrated within the Member States.

Because of the very newness of this area, the developments have

outstripped the establishment of relevant standards. The problem has beer,

recognized in the U.S.A. where the focus has been the E-^2 Committee of

the American Society for Testing and Materials (ASTM) , and in Europe

through the Community Reference Bureau. These programs have no formal

relation with one another but attempt, as far as is practicable, to be

complementary. Many other countries have projects which add to this body

of work in an ad-hoc manner, as demonstrated at the third International

Conference on Quantitative Surface Analysis at the U. K. National Physical

Laboratory in November, 1983. International collaboration is urgently

needed to make the most constructive use of this effort and to halt

divergencies of approach. Until fuller cooperation is achieved, the

prospect of surface chemical analyses entering into materials specifications and standards, in the way that bulk compositions do, cannot be

envisaged

3. Objective of the YAMAS Surface Chemical Analysis Working Party

A written proposal for the Coordinated Development of Standards for

Surface Chemical Analysis was submitted by the present authors to the

VAMAS Steering Committee and approved on June *8, '93-. T.ne objective cf

this VAMAS activity is to produce, by coordinated effort, that body of

reference procedures, data, and materials necessary to establish st r :

for surface chemical analysis.

3
4. Project Areas

We consider, here, work primarily, but not exclusively, associated

with the established surface analysis techniques of Auger electron

spectroscopy (AES) , X-ray photoelectron spectroscopy (XPS) , secondary ion

mass spectroscopy (SIMS) and inert-gas ion sputtering for composition

depth profiling (i.e., the measurement of composition versus depth). In

this section we shall list the basic requirements. In section 5 we shall

list current activities in the Member States and in section 6 we shall

list some possible action areas in broad terms.

Each of the above techniques, in its own way, gives information on

how much of each element is present at the surface, the chemical state and

spatial distribution, both across the surface and in depth through the

surface layers. The accuracy with which these data may be determined with

our current standards infra-structure leaves a great deal to be desired

although, as has already been mentioned, some positive moves have already

been initiated.

We may consider the structure of analysis using Fig. 3- Each

analysis consists of three parts which must be understood by the analyst

and which, if we are to establish a common basis, must be internationally

agreed upon:

(i) the principles of the physics of the measuring method

(ii) the behavior of the measuring instrument

(iii) the interpretation and expression of the measured result.

4
The basic principles of the physics of the techniques are vital since

they lead to the working formulae which we shall use for quantitative

analysis and which must be agreed when working to certain accuracies in

given situations for each technique. These formulae involve the measurement of intensities by the instrument which are then related to the

composition at the surface by functions of the material and the particular

measurement process (which need to be tabulated) and by functions of the

measuring instrument (which should be established by the user or be

tabulated by the manufacturer and be established as time invariant).

Additionally the measurements can give chemical information, the interpretation of which requires a similar hierarchy of understanding, data, and

reference procedures. Therefore, we envisage that the analyst requires:

(a) an agreed base of principles, definitions of terms and equations

to relate the techniques to the measurement,

(b) standards specifying how to measure intensities and spectral

features - reference procedures,

(c) procedures and data for calibrating instruments, determining

instrument functions and inter-relating instruments of different

designs

,

(d) reference data of elemental sensitivity factors, matrix terms,

information depth, libraries of chemical state spectra,

information on ion sputtering rates, radiation damage, etc.,

(e) standard methods of specifying an analysis.

The above are required for all the surface analysis techniques, of

which, in their order or popularity (i.e., number of instruments in use)

and therefore priority we order AES, XPS and SIMS. Standards will r. o

5
need to be developed for additional techniques of surface analysis (e.g.,

ion-scattering spectroscopy, Rutherford backscattering spectroscopy,

high-resolution electron energy-loss spectroscopy) as they become more

prevalent. This we envisage as a future sector of work in this VAMAS

proj ect

Below we list some of the most important problems currently requiring

attention. This listing focuses attention on specific areas within (a)

to (e) above and is in addition to those general comments. The list is

not exhaustive but attempts to highlight the urgent problems.

4(a) Auger electron spectroscopy

(i) Peak Area and Background Subtraction. In order to define the

intensity to be measured in AES the electron transport in the

solid should be understood as well as the decay process giving

the peak structure. This enables the true background to be

subtracted from the peak in the spectrum in order that the

true peak area, and hence intensity, can be determined. In

addition, practical but simpler equivalent background

substraction methods must be established and their accuracy

evaluated to provide working rules for routine analysis.

(ii) Differential Spectra. Peak intensities may alternatively be

measured in the so-called differential mode. For analog

(modulation) differentiation, an agreed specification is

required for the way this is to be done in order that

reference sensitivity factors may be used. For computer

differentiation, an agreed method must again be adopted so

that data will be transf erable

6
(iii) Electron Inelastic Mean Free Path. An integral parameter of

the electron transport in (i) is the electron attenuation

length (AL) which is related to the inelastic mean free path

(IMFP). The accuracy of theoretical expressions for the IMFP

for pure elements and for atomic mixtures and compounds needs

to be defined and the data base significantly increased. New

methods of determining ALs and IMFPs need to be considered and

rules given for establishing values for A and B in a material

AB.

(iv) Backscattering . Integral to the establishment of intensities

from mixtures of phases and from compounds are what are

commonly called matrix factors. These partly involve (iii)

and partly the backscattering terms. The backscattering terms

should be established for defined beam energies (say 2, 5 and

10 keV) and angles of incidence (0, 30 and 45°) with theoretical expressions and interpolation rules supported by a wide

experimental data base covering metals, alloys, inorganic

compounds and, if appropriate, organic compounds. Other

contributions to matrix terms must be assessed.

(v) Chemical State. Also stemming from (i) in the study of peak

structure is the effect of chemical state. With the use of

XPS instruments for AES this is now much more relevant and a

a data base of spectra (perhaps a library on floppy disc)

should be compiled (see 4(b) (iv)).

7
(vi) Relative Sensitivity Factors. A data bank of sensitivity

factors for different elements and compounds is required for

both the direct and derivative spectrum modes of intensity

measurement. These are required for defined beam energies

(say 2, 5 and 10 keV) and angles of incidence (0, 30 and 45°).

If these are defined for one instrument, its intensity/energy

response function (see viii) must be very accurately

established

(vii) Formulae. Quantification can proceed from the above for a

number of different situations such as monolayer partial

coverage, microprecipitates, layered structures, etc. Each is

calculated via a different basic equation involving different

matrix terms. An agreed set of equations must be established

in order that quantifications be readily understood.

(viii) Sp ectrometer

In order to use universal data banks for

quantification, the spectrometer intensity/ energy function

must be known. Reference methods, materials and data are

required to calibrate spectrometer intensity and energy scales

and to establish their constancy with time.

(ix) Other instrumental parameters. For defining instrument

performance and specifications a number of parameters must be

measured by agreed methods, such as energy resolution, spatial

resolution, and signal-to-noise ratio.

(x) Ion sputtering. See under 4(d)

8
Mb) X-ray photoelectron spectroscopy

(i) Peak Area and Background Subtraction. This problem is

parallel to 4(a) (i).

(ii) Electron Inelastic Mean Free Path. This problem is the same

as 4(a) (iii).

(iii) Matrix Terms. Matrix terms involving 4(b) (ii) have largely

been ignored in XPS and require both experimental and

theoretical consideration.

(iv) Chemical State. This is very important and of much greater

current use than 4(a) (v) . Further data are required on

spectra as a function of chemical state. Many data already

exist in the literature but their quality is variable and the

energy scales are not always properly referenced. These data

need to be appraised and compiled initially as tabulated data

for chemical shifts and later as spectra to show changes in

satellite features. Both types of files should be in data

banks to which new data could be readily added.

(v) Relative Sensitivity Factors. A data bank of sensitivity

factors for different elements and compounds is required for

A1 and Mg radiation. Effort needs to be focused on

discrepancies between the theoretical and experimental data

being produced. Angular asymmetry measurements are needed to

enable the effects of different instrument configurations to

be understood.

(vi) Formulae. Here, again, many parallels with AES exist for

requirements and methods.

9
(vii) Spectrometer

The spectrometer use and configuration in XPS

can be more variable and complex than for AES. Considerably

greater effort is therefore required to establish reference

methods, data, and procedures to determine spectrometer

intensity/energy response functions with known accuracy in

order to achieve good quantification from the core data base,

(viii) Other Instrumental Parameters. See 4(a)(ix).

(ix) Ion Sputtering. See 4(d)

4(c) Secondary Ion Mass Spectroscopy

Here we must consider two forms of SIMS, static and dynamic. Static

SIMS concerns surface analysis at the very low flux densities, before

discernable ion bombardment damage occurs, whereas dynamic SIMS concerns

thin film and bulk microscopic analysis generally for layers deeper than

10 nm from the surface. Modern instruments are beginning to bridge the

gap but it is useful here to note that certain requirements are necessary

for only one or other branch of the technique. Additionally, we should

note that if an energetic neutral beam is used in place of the ion beam in

static SIMS we have the technique called fast atom bombardment mass

spectroscopy ( FABMS) . FABMS has great commonality with static SIMS but

causes less damage and less sample charging.

(i) Intensities. Considerable effort is still required for both

static and dynamic SIMS as well as FABMS to relate measured

intensities to compositions theoretically. Matrix factors and

cracking patterns are still poorly understood. Effort needs

to be focused in this area but it will probably be sane time

before these techniques reach the state of certainty now

10
possible in AES and XPS (this is not meant to imply that AES

and XPS are better than SIMS/FABMS since the latter provide

far higher sensitivity than, and different data from the

former)

(ii) Chemical State. Cracking pattern spectra enable the precise

bonding state of groups on surfaces to be identified in Static

SIMS and FABMS. Libraries of spectra should be compiled (as

tables or on floppy disc) for certain surfaces of common

importance (e.g., organic coatings) to enable correct and

quantitative interpretations to be made. The spectra should

be for defined beams (Ar, Cs) at defined orientations and

energies (1, 2, 5 keV) , and for defined mass spectrometer

take-off angles.

(iii) Relative Sensitivity Factors. Because of the high matrix

sensitivity these are not as universal as in XPS and AES.

Nevertheless, since a considerable effort in both dynamic SIMS

and static SIMS/FABMS is confined to a few matrices, some

relative sensitivity factors should be compiled. This would

involve bond groupings on organic surfaces in static

SIMS/FABMS, on the one hand, and selected dopants in GaAs, Si

or Ge in dynamic SIMS on the other. Additionally, to ensure

traceability of the relative sensitivity factors, reference

materials of appropriate composition require establishment and

certification.

(iv) Formulae. Parallels with AES exist for requirements and

methods here as well as in XPS.
(v) Spectrometer. To ensure correct instrument behavior and to

use data banks and reference samples, the spectrometer ion

energy discrimination, ion mass transmission, and ion

detection functions must be established. Reference methods,

data, and materials are required to calibrate the instruments

and to ensure their constancy with time. The reference

materials here may or may not be a selection from (iii) and

may additionally characterize the energetic beam.

(vi) Other Instrumental Parameters. See 4(a) (ix).

(vii) Ion Sputtering. See 4(d).

4(d) Ion Sputtering

Ion or energetic neutral beams are involved with each of the above

techniques as well as in others such as ion scattering spectroscopy ( ISS)

The following projects therefore relate to surface analysis in general.

We need a better understanding of the ion-surface interaction leading to

theoretical predictions and experimental data for the following.

(i) Modification of the surface. For quantification we need to

know how sputtering alters the composition of multi-element

samples throughout the analysis depth. Predictions and data

should be limited to standard conditions of beam energy, angle

of incidence, and ion or neutral species.

(ii) Modification of the material. For quantification we also need

to know how the energetic ion alters the material beneath the

surface region, the problem of atomic mixing, and the extent

of differential sputtering (the amount by which one component

is removed faster than another).
(iii) Modification of the surface topography. This ill -understood

topic is important for understanding both the depth resolution

and variations in the depth profiling rate.

(iv) Sputtering Rate. Essential to the quantification of the depth

sputtered is the sputtering yield. Sputtering yields need to

be tabulated for fixed conditions of ion energy, angle of

incidence, and ion species for pure elements and, in addition,

accurate rules for their use in multi-element samples should

be established. Sputtering yields will alter with total

fluence, with the development of surface topography and with

temperature. These should be assessed at the same time.

(v) Instrumental Parameters. Additionally, for the quantification

of depth sputtered we need a reference material with known

thickness, sputtering yield, and other parameters with a

method for assessing and setting up the ion beam to obtain a

reproducible current density. The latter requires a study of

Faraday cup designs in order to establish a standard of

practical usefulness and known accuracy.

(vi) Formulae. Agreed formulae are required with an assessment of

their accuracy for use by surface analysts.

5. Current Activities of a Standards, Measurement or Quantification ‘iaturin Surface Chemical Analysis.

Below we list the current activity of organizations and individuals

known to be involved in VAMAS-related wor< in surface chemical analys: .

13
5(a) U.S.A.

(i) American Society for Testing and Materials ( ASTM)

The ASTM

Committee E-42 on Surface Analysis was established in 1976 to

advance the field of surface analysis and the quality of

surface analyses. There are currently 10 active subcommittees

dealing with separate aspects of surface analysis:

E42.01 Editorial

E42.02 Terminology

E42.03 Auger electron spectroscopy (AES)

E42.04 ESCA (or XPS)

E42.05 Ion scattering spectroscopy (ISS)

E42.06 Secondary ion mass spectroscopy (SIMS)

E42.07 Inactive

E42.08 Ion beam sputtering (IBS)

E42.09 Standard Reference Materials (SRM)

E42.10 Energetic Ion Analysis (EIA)

E42.11 Standard Reference Data (SRD)

Members of subcommittees consider work that is appropriate for

standards in their respective areas and (i) consider and write standard

definitions of terms (ii) consider, write and field test reference

procedures for assessing the instruments and their components, (iii)

consider, prepare and field test standard reference materials to

characterize instrument performance, and (iv) consider and prepare

algorithms for data analysis and identify needs for reference data. These

activities lead to the sponsorship of round robins, as shown in Appendix

14
1 . Standards already developed by the E-42 Committee and those under

development are listed in Appendix 2. In addition, the Committee

organi zes symposia and workshops and arranges publications.

(ii) National Bureau of Standards (NBS)

The relevant work at NBS is conducted within the Surface

Science Division. Division staff are active in ASTM topic

areas with in-depth studies, preparation of Standard Reference

Materials (SRMs), measurement of reference data for instrument

calibration and for quantitative analysis, and in the

publication of relevant review articles.

5(b) Europe

(i) Community Bureau of Reference (BCR)

The BCR assists individual projects in this area with work

conducted in Member States. Current work covers AES, XPS, IBS

and SIMS with the development of Certified Reference Materials

(CRMs), Reference Methodology, and Reference Data. Round

robins have been conducted, as shown in Appendix 3» leading to

publication of work in the open literature and to CRMs.

(ii) U.K. National Physical Laboratory (NPL)

At NPL the relevant work is conducted within the Interfacial

Microchemistry project of 3 to *1 staff members. Atomic

standards are developed, CRMs prepared and Reference

Methodology, Data and Procedures developed and tested through

interlaboratory comparisons and round robins. Some are given

in Appendix 3. The NPL organizes conferences on standards for

surface analysis and publishes relevant review articles.

15
(iii) Societe Francaise du Vide (SFV)

The French Vacuum Society's Surface Science Group is involved

in developing methods of spectrometer characteri zation , in

standards preparation, in developing calculation codes, and in

industrial applications of surface science.

5(c) International Union of Pure and Applied Chemistry (IUPAC)

The IUPAC Commission V.2 (microchemical techniques and trace

analysis) has recently established a Working Group on Surface Analysis.

This working group is chaired by Dr. M. Grasserbauer (Austria) and has

representatives from France, the Federal Republic of Germany, South

Africa, and the U.S.A. This group has developed plans to produce

reference methods, reference data, and reference materials for specific

problem areas in surface analysis.

6. Initial Projects Proposed For Coordination Through VAMAS

Scientists from all VAMAS Member States already contribute to our

basic understanding of the analytical techniques. Whilst we wish to focus

attention on certain objectives, as presented here, it must be recognized

that some of the problems will not be solved in the immediate future. In

order to promote improved analytical practices, the present authors plan

to provide a review of all quantification procedures and basic equations

so that the limits of accuracy for each is understood.

16
For AES, a coordinated effort on background subtraction methods for

peak area analysis will be conducted in the U.S.A. Backscattering terms

are a subject of intense analysis in Japan. Data are urgently required

for electron attenuation lengths/inelastic mean free paths (IMFPs) in AES

and XPS; the IMFP problem has been long recognized and requires a broad

effort between many nations. Data banks for peak shapes as a function of

chemical state may be considered as part of the parallel exercise for XPS

and would fit well with current efforts at NBS. Likewise efforts to

characterize electron spectrometer response function parallels that for

XPS and fits well with current efforts at NPL.

For XPS background subtraction, studies to define peak areas could be

coordinated between current efforts in the U.S.A. , Federal Republic of

Germany (F.R.G.), and U.K. The IMFP and spectrometer intensity-energy

response functions are mentioned above. Chemical state data for peak

shapes and positions are a current interest at NBS although it would be

very useful to extend and broaden the information in the data bank.

Matrix terms do not appear to be currently under investigation at all.

For static SIMS/FABMS, fragmentation patterns and standard spectra

for certain organic surfaces are being compiled in the U.K. and data banks

may be unified with that in the U.S.A. for XPS. Analysis of instrument

intensity-mass-specie response functions is a current interest in the U.K.

For dynamic SIMS, reference materials are required for the calibration of

depth profiling of dopants in electronic materials. These are currently

prepared in the ad-hoc manner in most Member States and coordinated effort

here could be very productive.

17
For ion sputter depth profiling, reference materials are available or

are becoming available from the NBS and NPL to define instrument operating

conditions and sputtering rate. At NBS, the work on pur e-element

sputtering yields could be extended to meet the requirements detailed

above and at NPL work on modifications of surface topography could be

combined with the considerable efforts in the F.R.G. to understand the ion

bombardment modifications of material compositions to provide a general

framework in this sector.

Relative sensitivity factors are important for each of the techniques

and at present only a skeletal data bank exists. A full program really

needs to be pursued once the peak area and background methods described

above, and other ancillary subjects, have been more firmly established.

We would view this to be important as a second phase of work.

7. Implementation

The VAMAS Surface Chemical Analysis Working Party consists of the

representatives from each of the member states as given in Table 1. These

individuals have been asked to identify scientists in their countries who

have expertise in the areas listed in section 4 and who could contribute

to this VAMAS project. In addition, they have been asked to identify

additional specific standards projects to supplement the listing in

Section 4. They would also interact with the appropriate national

standards body of their state.

It is expected that VAMAS-sponsored projects may be of several

different types. First, such projects may involve work by one or more

individuals in a particular nation on a given topic. Examples of such

18
projects may be found in current activities of the ASTM E-42 Committee on

Surface Analysis in the USA; recent accounts of the work of this committee

have been published by Nelson^ and Holloway. 22 Second, projects may

involve work on a given topic by scientists in two or more nations.

Examples of such projects are interlaboratory comparisons of measurements

of the same type, for example that published by Clegg et^^.^ Third,

projects may involve coordination with other appropriate national and

international organizations, for example the International Union of Pure

and Applied Chemistry, the Community Bureau of Reference of the C.E.C.,

the ASTM E-42 Committee, etc.

The principal objectives of this VAMAS activity in surface chemical

analysis are ( 1 ) to ensure international coordination of standar ds-related

activities before national standards are adopted, and (2) stimulate the

development of needed standards on an international basis. Individuals

who feel that their current or projected work would complement or add to

this VAMAS project are invited to contact their national working party

representative (Table 1) for further information and discussion.

Individuals of countries not a signatory to the VAMAS agreement are also

welcome and should contact a representative that they know or the Chairman

(C. J. Powell)

The VAMAS Surface Chemical Analysis Working Party will meet at

regular intervals to coordinate planned activities and to review progress.

Such meetings are expected to be held annually. The first meeting is

planned to be held at the time of the European Conference on Applications

of Surface and Interface Analysis, Veldhoven, The Netherlands, October

19
14-18, 1985. A second meeting is expected at the time of the Sixth

International Conference on Solid Surfaces and the Tenth International

Vacuum Congress, Baltimore, U.S.A., October 27-31. 1986.

20
Appendix 1. Round Robins Sponsored by ASTM Committees E-42 on Surface

Analysis and D-32 on Catalysts

1 . D-32

2. E-42.04

3. E-42. 03

4. E-42. 08

5. E-42. 03

Contact

6. E-43.05

Contact

7. E-42. 06

Contact:

8. E-42.08

Contact

9. E-42. 09

Contact

AES/XPS round robin on insulators and catalysts

T. E. Madey, C. D. Wagner and A. Joshi, J. Electron

Spectrosc. Relat. Phenom . 1_0» 359 ( 1977)

XPS round robin on gold and copper foils, C. J.

Powell, N. E. Erickson and T. E. Madey, J. Electron

Spectrosc. 1

, 361 (1979)

AES round robin on gold and copper foils, C. J.

Powell, N. E. Erickson and T. E. Madey, J. Electron

Spectrosc. 25_, 87 ( 1982)

Sputter rate determination for Ta^^ on Ta, A. J.

Bevolo, Surf. Interface Anal. 3_, 240 (1981)

AES round robin on Au/Cu binary alloys (in process)

P. H. Holloway, University of Florida, U.S.A.

ISS round robin on Ag/Cu/Au ternary alloys (in

process

)

A. Miller, Alcoa Laboratories, U.S.A.

SIMS round robin on 1

B implanted in Si (in process)

R. J. Colton, Naval Research Laboratory, U.S.A.

Sputter rate round robin for Si02 on Si (in process)

A. J. Bevolo, Ames Laboratory, U.S.A.

Standard reference material characterization - Ni/Cr

layered structures (in process)

J. Fine, National Bureau of Standards, U.S.A.

21
10. E-42.10

Contact:

11. E-42.04

Contact

Standard reference materials for high-energy ion

techniques - Au/Ti layered structures (in process)

J. A. Borders, Sandia National Laboratories , U.S.A.

Comparison of core-level binding energies determined

by x-ray photoelectron spectroscopy with instruments

calibrated using a field-emission electron source (in

process )

C. R. Anderson, Naval Surface Weapons Center, U.S.A.

22
Appendix 2. Standards and Recommended Practices Produced by ASTM

Committee E-42 on Surface Analysis

(a) Published Standards

E673-84: Standard Definitions of Terms Relating to Surface

Analysis

E684-83 : Practice for the Approximate Determination of the Current

Density of Large-Diameter Ion Beams for Depth Profiling of

Surfaces

E827-83

: Standard Practice for Elemental Identification by Auger

Electron Spectroscopy

E902-83 : Standard Practice for Checking the Operating

Characteristics of X-Ray Photoelectron Spectrometers

E983-84 : Standard Guide for Electron Beam Effects in Auger Electron

Spectroscopy

E984-84 : Standard Guide for Identifying Chemical Effects and Matrix

Effects in Auger Electron Spectroscopy

E995-84 : Standard Guide for Background Subtraction Techniques in

Auger Electron Spectroscopy

E996-84 : Standard Practice for Reporting Data in Auger Electron

Spe ctroscopy

El 01 5-84: Standard Practice for Reporting Spectra in ESCA

El 01 6-84: Standard Practice for Determining and Specifying the

Properties of Electrostatic Electron Spectrometers

23
(b) Standards Currently being Balloted

Additions to Standard Definitions of Terms Relating to Surface

Analysis (for ESCA and Energetic Ion Analysis methods)

Standard Guide for Specimen Handling in Auger Electron Spectroscopy

and X-Ray Photoelectron Spectroscopy

Standard Practice for Reporting Sputter Depth Profile Data in

Secondary Ion Mass Spectrometry (SIMS)

Standard Guide to Depth Profiling in Auger Electron Spectroscopy

2H
Appendix 3* Reference Data Procedures and Round Robins Sponsored by the

NPL-BCR Program

1 . XPS - Energy Calibration of Electron Spectrometers

1 - An Absolute Traceable Energy Calibration and the Provision of

Atomic Reference Line Energies by M. T. Anthony and M. P. Seah,

Surf. Interface Anal. 6_, 95 ( 1984).

2 - Results of an Interlaboratory Comparison by M. T. Anthony and M.

P. Seah, Surf. Interface Anal. 6_, 107 ( 1984).

2. Quantitative XPS: The Calibration of Spectrometer Intensity - Energy

Response Functions

1 - The Establishment of Reference Procedures and Instrument Behavior

by M. P. Seah and M. T. Anthony, Surf. Interface Anal. £, 230

(1984).

2 - Results of Interlaboratory Measurements for Commercial

Instruments by M. P. Seah, M. E. Jones and M. T. Anthony, Surf.

Interface Anal. 6_, 242 (1984).

3. Sputter - Depth Profiling

1 - Characterization of a High-Depth-Resolution Tantalum Pentoxide

Sputter Profiling Reference Material, C. P. Hunt and M. P. Seah,

Surf. Interface Anal., 5_, 199 ( 1983).

2 - AES and XPS Depth Profiling Certified Reference Material, C. P.

Hunt, M. T. Anthony, and M. P. Sean, Surf. Interface Anal., 6_, 92

(1984).

25
3 - The Ultra-High Resolution Depth Profiling

TagO^ Anodically Grown on Ta, M. P. Seah,

P. Hunt, Surf. Science 139, 549 (1984).

Reference Material -

H. J. Mathieu, and C.

26
References

1. D. Dickson, Science 224, 1317 (1984).

2. C. J. Powell, Appl . Surf. Sci . 1_, 143 ( 1978).

3. G. C. Nelson, Surf, and Interface Anal. 6_, 1 44 ( 1984).

4. P. H. Holloway, J. Vac. Sci. Tech. A 1, 1570 (1983).

5. J. B. Clegg, A. E. Morgan, H. A. M. de Grefte, F. Simondet , A.

Huber, G. Blackmore, M. G. Dowsett, D. E. Sykes, C. W. Magee, and

V. R. Deline, Surf, and Interface Anal. 6, 162 (1984).

27
Table 1. Technical Representatives to the Surface Chemical Analysis

Canada

France

Fed. Rep.

Italy

Working Party from the VAMAS Member States

N. S. McIntyre, Surface Science Western,

University of Western Ontario, London, Ontario,

Canada N6A 5B7 (519-679-6373).

C. Le Gressus, Department de Physico Chimie,

Section des Solides et des Suf aces

,

CEN Saclay, 91191 Gif-sur-Yvette Cedex, France

(6-908-4762) .

Germany S. Hofmann, Max-Planck-Institut fur

Metallforschung , Institut fur

Werkstoffwissenschaften, Seestrasse 92,

D 7000 Stuttgart 1, FRG (0711-2095-320).

H. Hantsche, Bundesanstalt ftir

Materialpriif ung, Unter den Eichen 87, D-1000

Berlin 45, FRG (030-8104-1).

F. Garbassi , Istituto Guido Donegani SpA, Centro

Ricerche Novara, Via G. Fauser 4, 28100 Novara,

Italy (0321-24701 )

28
G. Queirolo, SGS/ATES Canponenti Elettronici

SpA, Via C Olivetti 2, 20041 Agrate Brianza

(MI), Italy (6555-594).

Japan R. Shimizu, Department of Applied Physics,

Faculty of Engineering, Osaka University,

Suita, Osaka 565, Japan (06-877-5111, ext.

4658)

U.K. M. P. Seah, Division of Materials Applications,

National Physical Laboratory, Teddington,

Middlesex, TW1 1 OLW UK (01-977-3222, ext. 3634)

U.S.A. C. J. Powell (Chairman), Surface Science

Division, National Bureau of Standards,

Gaithersburg, MD 20899, USA (301-921-2188)

C.E.C. D. Gould, Bureau of Community Reference,

Commission of the European Communities, Rue oe la

Loi 200, 1940 Brussels, Belgium (02-235-931 3).

29
Figure Captions

Fig. 1.

Fig. 2.

Fig. 3 .

The intensity of application of surface analysis, illustrated by

the manufacturing sectors of the United Kingdom.

Countries of the world applying surface analysis.

The interacting components requiring specification to produce

quantitative analyses and statements of chemical state, as

illustrated schematically by components for x-ray photoelectron

spectroscopy

30
Lubrication

Wear

Paint adhesion

Batteries

Corrosion

Adhesives

Microcircuit

thin film stability adhesion failure dopant distributes

barrier layers

failure diagnosis Soldering and

metal wetting

Cleaning

Cathodes

Contacts

Lamps

Phosphors

Machining

Hardmetals

Corrosion

Oxidation

Tribology

Nit riding, carburizing

Rolling

Welding

Ball bearings

Cleaning

Machining

Power metallurgy

Superalloy oxidation

Fatigue failures

Adhesives

Finish, cosmetic

Joining

Welding

Soldering

Adhesives

3 High use D Occasional use mmm Rare use

Electroplating

Adhesives xxx*x;x:x x : x Laser and

opto-electromcs

Scientific instruments

.Dental, materials

Fibres:*®

Plastics x Printing orv: plastics

Flotation

Drill wear

Steel failures

temper brittleness creep cmbMlllcment

stress corrosion crocking weld rehcot crocking

Tokomak plasma / wall

Solar cells Fuel cells

i- i

rtO • 1 .
2 .
Ion source for prof 1 1 mg

Fig. 3.
NBS-114A (rev. 2 - U.S. DEPT. OF COMM.

BIBLIOGRAPHIC DATA

SHEET (See in structions)

1. PUBLICATION OR

REPORT NO.

NBSIR 85-3120

2. Performing Organ. Report No. 3. Publication Date March 1985

4. TITLE AND SUBTITLE

The Coordinated Development of Standards for Surface Chemical

Analysis

5. AUTHOR(S)

M. P. Seah and C. J. Powell

6. PERFORMING ORGANIZATION (If joint or other than N BS, see instructions)

national bureau of standards

DEPARTMENT OF COMMERCE

WASHINGTON, D.C. 20234

7. Contract/Grant No.

8 . Type of Report & Period Covered

9. SPONSORING ORGANIZATION NAME AND COMPLETE ADDRESS (Street. City. State. ZIP)

10. SUPPLEMENTARY NOTES

Document describes a computer program; SF-185, FIPS Software Summary, is attached.

11. ABSTRACT (A 200-word or less factual summary of most significant information . bi bi iography or literature survey , mention it here) This report is based on a proposal to the Steering Committee

If document includes a significant

of the Versailles

Project on Advanced Materials and Standards (VAMAS) for the coordinated development

amongst the VAMAS member states of standards for surface chemical analysis. VAMAS was established following a meeting of the Heads of State or government at Versailles,

France in 1982 that agreed on a number of projects relating to technology, growth,

and employment. Specifically, VAMAS was organized to promote international coordination

in the development of standards in a wide range of advanced material sectors. Surface

chemical analysis was approved as a VAMAS Technical Working Area in June, 1984.

The report describes the growth and diversity of surface analysis in the development

of advanced materials in modern technologies and additionally, the use of surface

analysis for improved films and coatings. The principal techniques of surface analysis

in common use are identified and the technical limitations to accurate surface analyses

identified. Accurate surface analyses require: (i) knowledge of the principles of the

measurement method, (ii) knowledge of the behavior of the measuring instrument, and

(iii) correct interpretation and expression of the final measured result. Standards

for the measurement of surface composition with known accuracy and for the reliable

determination of chemical state require: (a) a base of principles, definitions of terms,

and suitable equations, (b) reference procedures for the measurement of intensities

and spectral features, (c) procedures and data for instrument calibrations,

12. KEY WORDS (Six to twelve entries; alphabetical order; capitalize only proper names; and separate key words by semicolon s) reference data; reference materials; surface anlysis; surface standards;

Versailles Project on Advanced Materials and Standards

13. AVAILABILITY

C3unl imited

| | For Official Distribution. Do Not Release to NTIS

~\ Order From Superintendent of Documents, U.S. Government Printing Office, Washington, D.C. 20402.

Order From National Technical Information Service (NTIS), Springfield, VA. 22161

14. NO. OF

PRINTED PAGES

39

15. Price

U SCOMM'DC 6043-P80
(d) reference data for material parameters such as elemental sensitivity factors,

matrix terms, chemical state spectra, ion sputtering rates, etc; and (e) standard

methods for specifying an analysis. Specific needs are identified for the common methods of surface analysis. Auger-electron spectroscopy, x-ray photoelectron

spectroscopy, and secondary-ion mass spectroscopy together with the needs

for ion sputtering which is used to obtain composition versus depth information in films

and coatings. Existing standards activities in the member countries of VAMAS are reviewed

and suggestions are made for additional standards for surface chemical analysis.