ASTM F1593-08(2016)
(Test Method)Standard Test Method for Trace Metallic Impurities in Electronic Grade Aluminum by High Mass-Resolution Glow-Discharge Mass Spectrometer (Withdrawn 2023)
Standard Test Method for Trace Metallic Impurities in Electronic Grade Aluminum by High Mass-Resolution Glow-Discharge Mass Spectrometer (Withdrawn 2023)
SIGNIFICANCE AND USE
5.1 This test method is intended for application in the semiconductor industry for evaluating the purity of materials (for example, sputtering targets, evaporation sources) used in thin film metallization processes. This test method may be useful in additional applications, not envisioned by the responsible technical committee, as agreed upon by the parties concerned.
5.2 This test method is intended for use by GDMS analysts in various laboratories for unifying the protocol and parameters for determining trace impurities in pure aluminum. The objective is to improve laboratory to laboratory agreement of analysis data. This test method is also directed to the users of GDMS analyses as an aid to understanding the determination method, and the significance and reliability of reported GDMS data.
5.3 For most metallic species the detection limit for routine analysis is on the order of 0.01 weight ppm. With special precautions detection limits to sub-ppb levels are possible.
5.4 This test method may be used as a referee method for producers and users of electronic-grade aluminum materials.
SCOPE
1.1 This test method covers measuring the concentrations of trace metallic impurities in high purity aluminum.
1.2 This test method pertains to analysis by magnetic-sector glow discharge mass spectrometer (GDMS).
1.3 The aluminum matrix must be 99.9 weight % (3N-grade) pure, or purer, with respect to metallic impurities. There must be no major alloy constituent, for example, silicon or copper, greater than 1000 weight ppm in concentration.
1.4 This test method does not include all the information needed to complete GDMS analyses. Sophisticated computer-controlled laboratory equipment skillfully used by an experienced operator is required to achieve the required sensitivity. This test method does cover the particular factors (for example, specimen preparation, setting of relative sensitivity factors, determination of sensitivity limits, etc.) known by the responsible technical committee to affect the reliability of high purity aluminum analyses.
1.5 This standard does not purport to address all of the safety concerns, if any, associated with its use. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.
WITHDRAWN RATIONALE
This test method covers measuring the concentrations of trace metallic impurities in high purity aluminum.
Formerly under the jurisdiction of Committee F01 on Electronics, this test method was withdrawn in November 2023. This standard is being withdrawn without replacement because Committee F01 was disbanded.
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This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: F1593 − 08 (Reapproved 2016)
Standard Test Method for
Trace Metallic Impurities in Electronic Grade Aluminum by
High Mass-Resolution Glow-Discharge Mass Spectrometer
This standard is issued under the fixed designation F1593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision.Anumber in parentheses indicates the year of last reapproval.A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Determine the Precision of a Test Method
E1257Guide for Evaluating Grinding Materials Used for
1.1 Thistestmethodcoversmeasuringtheconcentrationsof
Surface Preparation in Spectrochemical Analysis
trace metallic impurities in high purity aluminum.
1.2 Thistestmethodpertainstoanalysisbymagnetic-sector
3. Terminology
glow discharge mass spectrometer (GDMS).
3.1 Terminology in this test method is consistent with
1.3 The aluminum matrix must be 99.9 weight % (3N-
Terminology E135. Required terminology specific to this test
grade)pure,orpurer,withrespecttometallicimpurities.There method and not covered in Terminology E135 is indicated
must be no major alloy constituent, for example, silicon or
below.
copper, greater than 1000 weight ppm in concentration.
3.2 campaign—a series of analyses of similar specimens
1.4 This test method does not include all the information
performed in the same manner in one working session, using
needed to complete GDMS analyses. Sophisticated computer- one GDMS setup. As a practical matter, cleaning of the ion
controlled laboratory equipment skillfully used by an experi-
source specimen cell is often the boundary event separating
enced operator is required to achieve the required sensitivity. one analysis campaign from the next.
Thistestmethoddoescovertheparticularfactors(forexample,
3.3 reference sample— material accepted as suitable for use
specimen preparation, setting of relative sensitivity factors,
as a calibration/sensitivity reference standard by all parties
determination of sensitivity limits, etc.) known by the respon-
concerned with the analyses.
sible technical committee to affect the reliability of high purity
3.4 specimen—asuitablysizedpiececutfromareferenceor
aluminum analyses.
test sample, prepared for installation in the GDMS ion source,
1.5 This standard does not purport to address all of the
and analyzed.
safety concerns, if any, associated with its use. It is the
3.5 test sample— material (aluminum) to be analyzed for
responsibility of the user of this standard to establish appro-
tracemetallicimpuritiesbythisGDMStestmethod.Generally
priate safety and health practices and determine the applica-
the test sample is extracted from a larger batch (lot, casting) of
bility of regulatory limitations prior to use.
product and is intended to be representative of the batch.
2. Referenced Documents
4. Summary of the Test Method
2.1 ASTM Standards:
4.1 A specimen is mounted as the cathode in a plasma
E135Terminology Relating to Analytical Chemistry for
discharge cell. Atoms subsequently sputtered from the speci-
Metals, Ores, and Related Materials
men surface are ionized, and then focused as an ion beam
E177Practice for Use of the Terms Precision and Bias in
through a double-focusing magnetic-sector mass separation
ASTM Test Methods
apparatus. The mass spectrum, that is, the ion current, is
E691Practice for Conducting an Interlaboratory Study to
collected as magnetic field, or acceleration voltage is scanned,
or both.
This test method is under the jurisdiction of ASTM Committee F01 on
4.2 The ion current of an isotope at mass M is the total
i
Electronics and is the direct responsibility of Subcommittee F01.17 on Sputter
measured current, less contributions from all other interfering
Metallization.
sources. Portions of the measured current may originate from
Current edition approved May 1, 2016. Published May 2016. Originally
the ion detector alone (detector noise). Portions may be due to
approved in 1995. Last previous edition approved in 2008 as F1593–08. DOI:
10.1520/F1593-08R16.
incompletelymassresolvedionsofanisotopeormoleculewith
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mass close to, but not identical with, M. In all such instances
i
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the interfering contributions must be estimated and subtracted
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. from the measured signal.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1593 − 08 (2016)
4.2.1 If the source of interfering contributions to the mea- 6. Apparatus
sured ion current at M cannot be determined unambiguously,
i
6.1 Glow Discharge Mass Spectrometer, with mass resolu-
the measured current less the interfering contributions from
tion greater than 3500, and associated equipment and supplies.
identified sources constitutes an upper bound of the detection
TheGDMSmustbefittedwithanionsourcespecimencellthat
limit for the current due to the isotope.
is cooled by liquid nitrogen, Peltier cooled, or cooled by an
4.3 The composition of the test specimen is calculated from
equivalent method.
the mass spectrum by applying a relative sensitivity factor
6.2 Machining Apparatus, capable of preparing specimens
(RSF(X/M)) for each contaminant element, X, compared to the
and reference samples in the required geometry and with
matrix element, M. RSFs are determined in a separate analysis
smooth surfaces.
of a reference material performed under the same analytical
6.3 Electropolishing Apparatus, capable of removing the
conditions, source configuration, and operating protocol as for
contaminants from the surfaces of specimens.
the test specimen.
4.4 The relative concentrations of elements X and Y are
7. Reagents and Materials
calculated from the relative isotopic ion currents I(X) and I(Y
i j
) in the mass spectrum, adjusted for the appropriate isotopic
7.1 Reagent and High Purity Grade Reagents, as required
abundance factors (A(X), A(Y)) and RSFs. I(X) and I(Y) refer
(MeOH, HNO , HCl).
i j i j 3
to the measured ion current from isotopes X and Y,
i j
7.2 Demineralized Water.
respectively, of atomic species X and Y.
7.3 Tantalum Reference Sample.
~X!/~Y! 5 RSF~X/M!/RSF~Y/M! 3A~Y !/A~X ! 3I X /I~Y !
~ !
j i i i
7.4 Aluminum Reference Sample.
(1)
7.4.1 Totheextentavailable,Aluminumreferencematerials
where (X)/(Y) is the concentration ratio of atomic species X
shall be used to produce the GDMS relative sensitivity factors
to species Y. If species Y is taken to be the aluminum matrix
for the various elements being determined (see Table 1).
(RSF(M/M)=1.0), (X) is (with only very small error for pure
7.4.2 As necessary, non-aluminum reference materials may
metal matrices) the absolute impurity concentration of X.
be used to produce the GDMS relative sensitivity factors for
the various elements being determined.
5. Significance and Use
7.4.3 Reference materials should be homogeneous and free
5.1 This test method is intended for application in the
of cracks or porosity.
semiconductor industry for evaluating the purity of materials
7.4.4 At least two reference materials are required to estab-
(for example, sputtering targets, evaporation sources) used in
lish the relative sensitivity factors, including one nominally
thin film metallization processes. This test method may be
99.9999% pure (6N-grade) aluminum metal to establish the
usefulinadditionalapplications,notenvisionedbytherespon-
background contribution in analyses.
sible technical committee, as agreed upon by the parties
7.4.5 The concentration of each analyte for relative sensi-
concerned.
tivity factor determination should be a factor of 100 greater
5.2 This test method is intended for use by GDMS analysts
than the detection limit determined using a nominally
invariouslaboratoriesforunifyingtheprotocolandparameters
99.9999% pure (6N-grade) aluminum specimen, but less than
for determining trace impurities in pure aluminum. The objec-
100 ppmw.
tive is to improve laboratory to laboratory agreement of
7.4.6 To meet expected analysis precision, it is necessary
analysis data. This test method is also directed to the users of
that specimens of reference and test material present the same
GDMS analyses as an aid to understanding the determination
size and configuration (shape and exposed length) in the glow
method, and the significance and reliability of reported GDMS
discharge ion source, with a tolerance of 0.2 mm in diameter
data.
and 0.5 mm in the distance of specimen to cell ion exit slit.
5.3 For most metallic species the detection limit for routine
8. Preparation of Reference Standards and Test
analysis is on the order of 0.01 weight ppm. With special
Specimens
precautions detection limits to sub-ppb levels are possible.
5.4 This test method may be used as a referee method for 8.1 The surface of the parent material must not be included
producers and users of electronic-grade aluminum materials. in the specimen.
A
TABLE 1 Suite of Impurity Elements to Be Analyzed
NOTE 1—Establish RSFs for the following suite of elements.
silver arsenic gold boron beryllium calcium cerium chromium cesium copper iron
potassium lithium magnesium manganese sodium nickel phosphorus antimony silicon tin thorium
titanium uranium vanadium zinc zirconium
A
Additional species may be determined and reported, as agreed upon between all parties concerned with the analyses.
F1593 − 08 (2016)
8.2 The machined surface of the specimen must be cleaned ciency of each detector relative to the others should be
by electropolishing or etching immediately prior to mounting determined at least weekly.
the specimen and inserting it into the glow discharge ion
9.5.1 If both Faraday cup collector for ion current measure-
source.
ment and ion counting detectors are used during the same
8.2.1 Inordertoobtainarepresentativebulkcompositionin analysis, the ion counting efficiency (ICE) must be determined
a reasonable analysis time, surface cleaning must remove all prior to each campaign of specimen analyses using the follow-
contaminantswithoutalteringthecompositionofthespecimen ing or equivalent procedures.
surface. 9.5.1.1 Using a specimen of tantalum, measure the ion
8.2.2 To minimize the possibility of contamination, clean current from the major isotope ( Ta) using the ion current
Faraday cup detector, and measure the ion current from the
eachspecimenseparatelyimmediatelypriortomountinginthe
glow discharge ion source. minorisotope( Ta)usingtheioncountingdetector,withcare
to avoid ion counting losses due to ion counting system dead
8.2.3 Prepare and use electropolishing or etching solutions
times. The counting loss should be 1% or less.
in a clean container insoluble in the contained solution.
9.5.1.2 The ion counting efficiency is calculated by multi-
8.2.4 Electropolishing— perform electropolishing in a solu-
180 181
plyingtheratioofthe Taioncurrenttothe Taioncurrent
tion of methanol and HNO mixed in the ratio 7:5 by volume.
181 180
by the Ta/ Ta isotopic ratio. The result of this calculation
Apply 5–15 volts (dc) across the cell, with the specimen as
is the ion counting detector efficiency (ICE).
anode. Electropolish for up to 4 min, as sufficient to expose
9.5.1.3 Apply the ICE as a correction to all ion current
smooth, clean metal over the entire polished surface.
measurements from the ion counting detector obtained in
8.2.5 Etching—performetchingbyimmersingthespecimen
analyses by dividing the ion current by the ICE factor.
in aqua regia (HNO and HF, mixed in the ratio 3:1 by
volume).Etchforseveralminutes,untilsmooth,cleanmetalis
10. Instrument Quality Control
exposed over the entire surface.
8.2.6 Immediately after cleaning, wash the specimen with
10.1 A well-characterized specimen must be run on a
several rinses of high purity methanol or other high purity
regular basis to demonstrate the capability of the GDMS
reagent to remove water from the specimen surface, and dry
system as a whole for the required analyses.
the specimen in the laboratory environment.
10.2 A recommended procedure is the measurement of the
8.3 Immediately mount and insert the specimen into the
relative ion currents of selected analytes and the matrix
glow discharge ion source, minimizing exposure of the
element in aluminum or tantalum reference samples.
cleaned, rinsed specimen surface to the laboratory environ-
10.3 Plotvalidationanalysisdatafromatleastfiveelements
ment.
with historic values in statistical process control (SPC) chart
8.3.1 As necessary, use a non-contacting gage when mount-
format to demonstrate that the analysis process is in statistical
ing specimens in the analysis cell specimen holder to ensure
control. The equipment is suitable for use if the analysis data
thepropersampleconfigurationintheglowdischargecell(see
group is within the 3-sigma control limits and shows no
7.4.6).
non-random trends.
8.4 Sputter etch the specimen surface in the glow discharge
10.4 UpperandlowercontrollimitsforSPCmustbewithin
plasma for a period of time before data acquisition (see 12.3)
at least 20% of the mean of previously determined values of
to ensure the cleanliness of the surface. Pre-analysis sputtering
the relative ion currents.
conditionsarelimitedbytheneedtomaintainsampleintegrity.
Pre-analysissputteringattwicethepowerusedfortheanalysis
11. Standardization
should be adequate for sputter etch cleaning.
11.1 The GDMS instrument should be standardized using
National Institute of Standards Technology (NIST) traceable
9. Preparation of the GDMS Apparatus
reference materials, preferably aluminum, to the extent such
9.1 The ultimate background pressure in the ion source
reference samples are available.
−6
chamber should be less than 1×10 Torr before operation.
11.2 Relative sensitivity factor (RSF) values should, in the
The background pressure in the mass analyzer should be less
−7
bestcase,bedeterminedfromtheionbeamratiomeasurements
than 5×10 Torr during operation.
of four randomly selected specimens from each standard
9.2 The glow discharge ion source must be cooled to near
required, with four independent measurements of each pin.
liquid nitrogen temperature.
11.3 RSF values must be determined for the suite of
9.3 The GDMS instrument must be accurately mass cali-
impurityelementsforwhichspecimensaretobeanalyzed(see
brated prior to measurements.
Table 1) using the selec
...
NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
Contact ASTM International (www.astm.org) for the latest information
Designation: F1593 − 08 (Reapproved 2016)
Standard Test Method for
Trace Metallic Impurities in Electronic Grade Aluminum by
High Mass-Resolution Glow-Discharge Mass Spectrometer
This standard is issued under the fixed designation F1593; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope Determine the Precision of a Test Method
E1257 Guide for Evaluating Grinding Materials Used for
1.1 This test method covers measuring the concentrations of
Surface Preparation in Spectrochemical Analysis
trace metallic impurities in high purity aluminum.
1.2 This test method pertains to analysis by magnetic-sector
3. Terminology
glow discharge mass spectrometer (GDMS).
3.1 Terminology in this test method is consistent with
1.3 The aluminum matrix must be 99.9 weight % (3N- Terminology E135. Required terminology specific to this test
grade) pure, or purer, with respect to metallic impurities. There
method and not covered in Terminology E135 is indicated
must be no major alloy constituent, for example, silicon or below.
copper, greater than 1000 weight ppm in concentration.
3.2 campaign—a series of analyses of similar specimens
1.4 This test method does not include all the information performed in the same manner in one working session, using
needed to complete GDMS analyses. Sophisticated computer-
one GDMS setup. As a practical matter, cleaning of the ion
controlled laboratory equipment skillfully used by an experi- source specimen cell is often the boundary event separating
enced operator is required to achieve the required sensitivity.
one analysis campaign from the next.
This test method does cover the particular factors (for example,
3.3 reference sample— material accepted as suitable for use
specimen preparation, setting of relative sensitivity factors,
as a calibration/sensitivity reference standard by all parties
determination of sensitivity limits, etc.) known by the respon-
concerned with the analyses.
sible technical committee to affect the reliability of high purity
3.4 specimen—a suitably sized piece cut from a reference or
aluminum analyses.
test sample, prepared for installation in the GDMS ion source,
1.5 This standard does not purport to address all of the
and analyzed.
safety concerns, if any, associated with its use. It is the
3.5 test sample— material (aluminum) to be analyzed for
responsibility of the user of this standard to establish appro-
trace metallic impurities by this GDMS test method. Generally
priate safety and health practices and determine the applica-
the test sample is extracted from a larger batch (lot, casting) of
bility of regulatory limitations prior to use.
product and is intended to be representative of the batch.
2. Referenced Documents
4. Summary of the Test Method
2.1 ASTM Standards:
4.1 A specimen is mounted as the cathode in a plasma
E135 Terminology Relating to Analytical Chemistry for
discharge cell. Atoms subsequently sputtered from the speci-
Metals, Ores, and Related Materials
men surface are ionized, and then focused as an ion beam
E177 Practice for Use of the Terms Precision and Bias in
through a double-focusing magnetic-sector mass separation
ASTM Test Methods
apparatus. The mass spectrum, that is, the ion current, is
E691 Practice for Conducting an Interlaboratory Study to
collected as magnetic field, or acceleration voltage is scanned,
or both.
This test method is under the jurisdiction of ASTM Committee F01 on 4.2 The ion current of an isotope at mass M is the total
i
Electronics and is the direct responsibility of Subcommittee F01.17 on Sputter
measured current, less contributions from all other interfering
Metallization.
sources. Portions of the measured current may originate from
Current edition approved May 1, 2016. Published May 2016. Originally
the ion detector alone (detector noise). Portions may be due to
approved in 1995. Last previous edition approved in 2008 as F1593 – 08. DOI:
10.1520/F1593-08R16.
incompletely mass resolved ions of an isotope or molecule with
For referenced ASTM standards, visit the ASTM website, www.astm.org, or
mass close to, but not identical with, M . In all such instances
i
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
the interfering contributions must be estimated and subtracted
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website. from the measured signal.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
F1593 − 08 (2016)
4.2.1 If the source of interfering contributions to the mea- 6. Apparatus
sured ion current at M cannot be determined unambiguously,
i
6.1 Glow Discharge Mass Spectrometer, with mass resolu-
the measured current less the interfering contributions from
tion greater than 3500, and associated equipment and supplies.
identified sources constitutes an upper bound of the detection
The GDMS must be fitted with an ion source specimen cell that
limit for the current due to the isotope.
is cooled by liquid nitrogen, Peltier cooled, or cooled by an
4.3 The composition of the test specimen is calculated from
equivalent method.
the mass spectrum by applying a relative sensitivity factor
6.2 Machining Apparatus, capable of preparing specimens
(RSF(X/M)) for each contaminant element, X, compared to the
and reference samples in the required geometry and with
matrix element, M. RSFs are determined in a separate analysis
smooth surfaces.
of a reference material performed under the same analytical
6.3 Electropolishing Apparatus, capable of removing the
conditions, source configuration, and operating protocol as for
contaminants from the surfaces of specimens.
the test specimen.
4.4 The relative concentrations of elements X and Y are
7. Reagents and Materials
calculated from the relative isotopic ion currents I(X ) and I(Y
i j
) in the mass spectrum, adjusted for the appropriate isotopic
7.1 Reagent and High Purity Grade Reagents, as required
abundance factors (A(X ), A(Y )) and RSFs. I(X ) and I(Y ) refer (MeOH, HNO , HCl).
i j i j
to the measured ion current from isotopes X and Y ,
i j
7.2 Demineralized Water.
respectively, of atomic species X and Y.
7.3 Tantalum Reference Sample.
X / Y 5 RSF X/M /RSF Y/M 3A Y /A X 3I X /I Y
~ ! ~ ! ~ ! ~ ! ~ ! ~ ! ~ ! ~ !
j i i i
7.4 Aluminum Reference Sample.
(1)
7.4.1 To the extent available, Aluminum reference materials
where (X)/(Y) is the concentration ratio of atomic species X
shall be used to produce the GDMS relative sensitivity factors
to species Y. If species Y is taken to be the aluminum matrix
for the various elements being determined (see Table 1).
(RSF(M/M) = 1.0), (X) is (with only very small error for pure
7.4.2 As necessary, non-aluminum reference materials may
metal matrices) the absolute impurity concentration of X.
be used to produce the GDMS relative sensitivity factors for
the various elements being determined.
5. Significance and Use
7.4.3 Reference materials should be homogeneous and free
5.1 This test method is intended for application in the
of cracks or porosity.
semiconductor industry for evaluating the purity of materials
7.4.4 At least two reference materials are required to estab-
(for example, sputtering targets, evaporation sources) used in
lish the relative sensitivity factors, including one nominally
thin film metallization processes. This test method may be
99.9999 % pure (6N-grade) aluminum metal to establish the
useful in additional applications, not envisioned by the respon-
background contribution in analyses.
sible technical committee, as agreed upon by the parties
7.4.5 The concentration of each analyte for relative sensi-
concerned.
tivity factor determination should be a factor of 100 greater
5.2 This test method is intended for use by GDMS analysts
than the detection limit determined using a nominally
in various laboratories for unifying the protocol and parameters
99.9999 % pure (6N-grade) aluminum specimen, but less than
for determining trace impurities in pure aluminum. The objec-
100 ppmw.
tive is to improve laboratory to laboratory agreement of
7.4.6 To meet expected analysis precision, it is necessary
analysis data. This test method is also directed to the users of
that specimens of reference and test material present the same
GDMS analyses as an aid to understanding the determination
size and configuration (shape and exposed length) in the glow
method, and the significance and reliability of reported GDMS
discharge ion source, with a tolerance of 0.2 mm in diameter
data.
and 0.5 mm in the distance of specimen to cell ion exit slit.
5.3 For most metallic species the detection limit for routine
8. Preparation of Reference Standards and Test
analysis is on the order of 0.01 weight ppm. With special
Specimens
precautions detection limits to sub-ppb levels are possible.
5.4 This test method may be used as a referee method for 8.1 The surface of the parent material must not be included
producers and users of electronic-grade aluminum materials. in the specimen.
A
TABLE 1 Suite of Impurity Elements to Be Analyzed
NOTE 1—Establish RSFs for the following suite of elements.
silver arsenic gold boron beryllium calcium cerium chromium cesium copper iron
potassium lithium magnesium manganese sodium nickel phosphorus antimony silicon tin thorium
titanium uranium vanadium zinc zirconium
A
Additional species may be determined and reported, as agreed upon between all parties concerned with the analyses.
F1593 − 08 (2016)
8.2 The machined surface of the specimen must be cleaned ciency of each detector relative to the others should be
by electropolishing or etching immediately prior to mounting determined at least weekly.
the specimen and inserting it into the glow discharge ion
9.5.1 If both Faraday cup collector for ion current measure-
source.
ment and ion counting detectors are used during the same
8.2.1 In order to obtain a representative bulk composition in analysis, the ion counting efficiency (ICE) must be determined
a reasonable analysis time, surface cleaning must remove all prior to each campaign of specimen analyses using the follow-
contaminants without altering the composition of the specimen ing or equivalent procedures.
surface.
9.5.1.1 Using a specimen of tantalum, measure the ion
current from the major isotope ( Ta) using the ion current
8.2.2 To minimize the possibility of contamination, clean
each specimen separately immediately prior to mounting in the Faraday cup detector, and measure the ion current from the
minor isotope ( Ta) using the ion counting detector, with care
glow discharge ion source.
to avoid ion counting losses due to ion counting system dead
8.2.3 Prepare and use electropolishing or etching solutions
times. The counting loss should be 1 % or less.
in a clean container insoluble in the contained solution.
9.5.1.2 The ion counting efficiency is calculated by multi-
8.2.4 Electropolishing— perform electropolishing in a solu-
180 181
plying the ratio of the Ta ion current to the Ta ion current
tion of methanol and HNO mixed in the ratio 7:5 by volume.
181 180
by the Ta/ Ta isotopic ratio. The result of this calculation
Apply 5–15 volts (dc) across the cell, with the specimen as
is the ion counting detector efficiency (ICE).
anode. Electropolish for up to 4 min, as sufficient to expose
9.5.1.3 Apply the ICE as a correction to all ion current
smooth, clean metal over the entire polished surface.
measurements from the ion counting detector obtained in
8.2.5 Etching—perform etching by immersing the specimen
analyses by dividing the ion current by the ICE factor.
in aqua regia (HNO and HF, mixed in the ratio 3:1 by
volume). Etch for several minutes, until smooth, clean metal is
10. Instrument Quality Control
exposed over the entire surface.
8.2.6 Immediately after cleaning, wash the specimen with
10.1 A well-characterized specimen must be run on a
several rinses of high purity methanol or other high purity
regular basis to demonstrate the capability of the GDMS
reagent to remove water from the specimen surface, and dry
system as a whole for the required analyses.
the specimen in the laboratory environment.
10.2 A recommended procedure is the measurement of the
8.3 Immediately mount and insert the specimen into the
relative ion currents of selected analytes and the matrix
glow discharge ion source, minimizing exposure of the
element in aluminum or tantalum reference samples.
cleaned, rinsed specimen surface to the laboratory environ-
10.3 Plot validation analysis data from at least five elements
ment.
with historic values in statistical process control (SPC) chart
8.3.1 As necessary, use a non-contacting gage when mount-
format to demonstrate that the analysis process is in statistical
ing specimens in the analysis cell specimen holder to ensure
control. The equipment is suitable for use if the analysis data
the proper sample configuration in the glow discharge cell (see
group is within the 3-sigma control limits and shows no
7.4.6).
non-random trends.
8.4 Sputter etch the specimen surface in the glow discharge
10.4 Upper and lower control limits for SPC must be within
plasma for a period of time before data acquisition (see 12.3)
at least 20 % of the mean of previously determined values of
to ensure the cleanliness of the surface. Pre-analysis sputtering
the relative ion currents.
conditions are limited by the need to maintain sample integrity.
Pre-analysis sputtering at twice the power used for the analysis
11. Standardization
should be adequate for sputter etch cleaning.
11.1 The GDMS instrument should be standardized using
National Institute of Standards Technology (NIST) traceable
9. Preparation of the GDMS Apparatus
reference materials, preferably aluminum, to the extent such
9.1 The ultimate background pressure in the ion source
reference samples are available.
−6
chamber should be less than 1 × 10 Torr before operation.
11.2 Relative sensitivity factor (RSF) values should, in the
The background pressure in the mass analyzer should be less
−7
best case, be determined from the ion beam ratio measurements
than 5 × 10 Torr during operation.
of four randomly selected specimens from each standard
9.2 The glow discharge ion source must be cooled to near
required, with four independent measurements of each pin.
liquid nitrogen temperature.
11.3 RSF values must be determined for the suite of
9.3 The GDMS instrument must be accurately mass cali-
impuri
...
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