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SEMI F72-1102 © SEMI 2002 3 11 Test Specimens 11.1 Specimens are to be sectioned to appropriate size for the particu lar AES instrum ent using a clean, dry hacksaw or dry low s p eed bandsaw. Any sample preparation shall…

SEMI F72-1102 © SEMI 2002 2

4.2 ASTM

Standards

ASTM E 673 — Standard Terminology Relating to

Surface Analysis

ASTM E 1078 — Standard Guide for Specimen

Handling in Auger Electron Spectroscopy and X-ray

Photoelectron Spectroscopy

ASTM E 1127 — Standard Guide for Depth Profiling

in Auger Electron Spectroscopy

NOTE 1: Unless otherwise indicated, all documents cited

shall be the latest published versions

5 Terminology

5.1 Terminology is per ASTM E 673 unless otherwise

specified.

5.2 Abbreviations and Acronyms

5.2.1 AES — Auger Electron Spectroscopy

5.3 Definitions

5.3.1 passivation — the chemical treatment of a

stainless steel surface with a mild oxidant for the

purpose of enhancing the corrosion resistant surface

film.

5.3.2 sampling volume — the volume in the sample

from which Auger electrons are detected. The electron

beam spot size or the scan area, and the acceptance

angle of the electron analyzer determine the lateral

dimensions. A length of three times the Auger electron

mean free path is considered the maximum depth

sensitivity. Sampling volume is dependent on the

sample material and TOA.

5.3.3 take-off angle (TOA) — the angle that the

collection lens forms with the sample plane.

6 Summary of Method

6.1 Data Acquisition

6.1.1 Acquire initial elemental survey and calculate

elemental composition of “as received” wetted surface.

6.1.2 Acquire a compositional depth profile by ion

etching to determine the relative abundance of C, O, Cr,

Fe and Ni. Additional elements may be included as

desired (i.e., molybdenum, silicon and nitrogen). The

thickness of the passive oxide layer and carbon is also

determined from the depth profile.

1 American Society for Testing and Materials, 100 Barr Harbor

Drive, West Conshohocken, Pennsylvania 19428-2959, USA.

Telephone: 610.832.9585, Fax: 610.832.9555 Website:

www.astm.org

6.2 Reporting — Data is provided consisting of:

6.2.1 An initial survey spectrum extending from

approximately 0 to 2000 eV.

6.2.2 A compositional depth profile plot including C,

O, Cr, Fe and Ni as a function of sputtering time.

6.2.3 A table of the as-received surface elemental

composition calculated from the initial survey

spectrum.

6.2.4 A table of the oxide thickness, the carbon

thickness, and the maximum of the Chromium to Iron

ratio calculated from the depth profile.

7 Possible Interferences

7.1 Cr and O — Carefully select windows for oxygen

and chromium to minimize interference. Monitor

individual windows after profile is complete to evaluate

effects. Some instruments may have enhanced ability

to compensate for overlaps.

8 Apparatus

8.1 Instrumentation — Any AES instrument equipped

with an ion gun may be used, whether it etches and

measures simultaneously or in alternating fashion. An

instrument that analyzes and etches in alternating

fashion should be evaluated to assure that no significant

oxygen level redeposits onto the sample surface

between etching intervals. The electron analyzer may

be of either the hemispherical or cylindrical mirror

analyzer (CMA) type. The electron energy analyzer

shall be of high enough energy resolution to permit

adequate separation of the Chromium KLL and Oxygen

KLL Auger peaks.

8.2 Instruments with geometries significantly different

from one another may provide analysis from different

sampling volumes. The incident electron beam energy,

the angle of the incident electron beam to the sample

plane, and the take-off angle must be recorded.

9 Reagents and Materials

9.1 Instrument Calibration Materials — Refer to

instrument manufacturer recommendations or ASTM E

1127 for standard materials.

10 Safety Precautions

10.1 This test method does not purport to address the

safety considerations associated with use of high

voltage, vacuum, and electron producing equipment.

The method assumes an AES analyst with adequate

skill level as well as knowledge of instrumentation and

associated safety precautions.

SEMI F72-1102 © SEMI 2002 3

11 Test Specimens

11.1 Specimens are to be sectioned to appropriate size

for the particular AES instrument using a clean, dry

hacksaw or dry low speed bandsaw. Any sample

preparation shall avoid introducing contamination onto

the surface to be measured. Clean noncontaminating

gloves and tweezers should be used to handle samples,

avoiding contact with the area of interest. In addition,

preparation must avoid excessive heating of the sample;

i.e., the surface temperature shall not exceed 50

C, to

avoid oxide growth or change in surface composition.

11.2 Sample preparation should preferably be done by

the component manufacturer. Following sectioning the

sample(s) are to be cleaned and packaged per the

manufacturer’s standard final cleaning and packaging

procedures.

11.3 If sample preparation is done by other than the

manufacturer, the sample(s) may be cleaned in DI water

and dried promptly. If the sample(s) are not to be

analyzed immediately they should be packaged by

wrapping in clean metal foil or sealing in cleanroom

quality nylon bags.

11.4 If sample preparation is done by other than the

manufacturer this shall be stated in the report narrative

and the analytical results are not to be interpreted as

indicative of the manufacturer’s quality of cleaning and

packaging procedures. A note to this effect shall be

included in all tables of reported results of the

composition of the surface.

11.5 After preparation, samples should be analyzed

promptly, with allowance for shipping times and

queuing time at the analyst.

12 Preparation of Apparatus

12.1 Instruments shall be routinely tested in

accordance with manufacturer recommendations to

assure proper performance. The instrument vacuum

shall be 1.0 × 10

-7

Torr or better during the analysis.

13 Calibration and Standardization

13.1 Instrument calibration for etch rates and

sensitivity factors shall be performed in accordance

with instrument manufacturer recommendations or

other established method.

14 Procedure

14.1 The sample is to be mounted in accordance with

manufacturer's recommendations and in a manner

consistent with ultra-high vacuum surface analytical

procedures. Some of these practices are detailed in

ASTM E 1078. The area to be analyzed should be

mounted parallel to the sample holder surface so that

the TOA is known.

14.2 Place the sample in the AES introduction chamber

for pumpdown. Transfer to the analytical chamber at

the manufacturer's recommended base pressure.

14.3 Align the sample with respect to the electron

beam and analyzer so that optimum count rate from the

desired analytical location is obtained. The surface area

to be analyzed should be free of sample preparation

debris, visible particles and large defect features, if

possible.

14.4 A large beam size or scan area should be used to

attempt measurement of a representative surface.

Elemental survey data (approximately 0-2000 eV) are

to be measured from the sample surface to determine

the elements present and their approximate surface

abundances. A signal-to-noise ratio of 2 is usually

adequate to ensure detection of elements present at one

atomic percent or greater levels. A typical survey

spectrum is shown in Figure 1.

Figure 1

Auger Spectrum of Stainless Steel Surface

14.5 Acquire a depth composition profile to determine

the relative abundances of Cr, Fe, Ni, O, and C. The

profile may be acquired in a simultaneous or an

alternating etch/data acquisition mode. Measurement

of each element shall be made at a frequency of at least

one data point every 5 Å within the first 50 Å and one

data point every 10 Å from 50 Å to the profile end. An

appropriate scan acquisition time is one that optimizes

spectral resolution and signal/noise, and that has at least

ten data points in each spectral window. The depth

profile should be continued into the depth of the sample

until the Fe, Cr and Ni levels are approximately

constant.

14.6 Depth profile data are presented as signal intensity

of each element with etch time (i.e., depth), and as

atomic concentration with etch time. Depths may be

estimated from etch times by determination of the etch

rate on a known thickness of standard material. A

typical AES profile is shown in Figure 2.

Figure 2

Auger Depth Profile of Stainless Steel

15 Calculations and Interpretation of Results

15.1 Most manufacturers supply software for

calculation of the approximate elemental composition

from the survey spectrum and the depth profile data.

The elemental composition should be estimated using

sensitivity factors appropriate to the instrument, each

element, and resolution settings for each measurement.

AES spectra are considered only semiquantitative, due

to instrument geometry and the chemical form

dependency of each element's sensitivity factor.

Evaluations of elemental composition should therefore

be limited to similar samples analyzed on the same

instrument.

15.2 The signal intensity with etch time graph may be

used to calculate oxide thickness, defined as the point at

which the oxygen signal decreases to half its maximum

value. The thickness of surface carbon contamination

is calculated in the same way from the carbon signal.

15.3 Relative abundances of profiled elements are

recorded on the atomic concentration with etch time

graph.

16 Reporting Results

16.1 A tabular summary of estimated surface elemental

composition is to be supplied with its associated

elemental survey spectrum.

16.2 Tabular summaries of oxide thickness, thickness

of the region in which Cr concentration exceeds Fe

concentration, thickness of a surface Fe enrichment (if

present), and carbon thickness are to be supplied with

associated depth profile graphs.

16.3 Optionally, parameters such as maximum Cr/Fe

ratio may be reported. However, the value of the

maximum Cr/Fe ratio is subject to instrument geometry

and sensitivity factor variations, and should not be used

for primary evaluation purposes. Comparative

evaluations should only be made from data collected by

the same instrument with an identical protocol.

16.4 Data acquisition parameters, including instrument

geometry, electron beam size or scan area, and other

pertinent settings are to be supplied. The manufacturer

and model number of instrument used is to be reported.

Analyst identity and analysis date are also required

information. Each table and graph must be clearly

labeled with sample identification.

NOTICE: SEMI makes no warranties or

representations as to the suitability of the standards set

forth herein for any particular application. The

determination of the suitability of the standard is solely

the responsibility of the user. Users are cautioned to

refer to manufacturer's instructions, product labels,

product data sheets, and other relevant literature,

respecting any materials or equipment mentioned

herein. These standards are subject to change without

notice.

By publication of this standard, Semiconductor

Equipment and Materials International (SEMI) takes no

position respecting the validity of any patent rights or

copyrights asserted in connection with any items

mentioned in this standard. Users of this standard are

expressly advised that determination of any such patent

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