ASTM F1710-97(2002)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F 1710–97 (Reapproved 2002)
Standard Test Method for
Trace Metallic Impurities in Electronic Grade Titanium by
High Mass-Resolution Glow Discharge Mass Spectrometer
This standard is issued under the fixed designation F 1710; 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 (e) 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 the determination of concentra-
Surface Preparation in Spectrochemical Analysis
tions of trace metallic impurities in high purity titanium.
1.2 Thistestmethodpertainstoanalysisbymagnetic-sector
3. Terminology
glow discharge mass spectrometer (GDMS).
3.1 Terminology in this test method is consistent with
1.3 The titanium matrix must be 99.9 weight % (3N-grade)
Terminology E135. Required terminology specific to this test
pure, or purer, with respect to metallic impurities. There must
method, not covered inTerminology E135, is indicated in 3.2.
be no major alloy constituent, for example, aluminum or iron,
3.2 Definitions:
greater than 1000 weight ppm in concentration.
3.2.1 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.
controlled laboratory equipment skillfully used by an experi-
3.2.1.1 Discussion—As a practical matter, cleaning of the
enced operator is required to achieve the required sensitivity.
ionsourcespecimencellisoftentheboundaryeventseparating
Thistestmethoddoescovertheparticularfactors(forexample,
one analysis campaign from the next.
specimen preparation, setting of relative sensitivity factors,
3.2.2 reference sample—material accepted as suitable for
determination of sensitivity limits, etc.) known by the respon-
use as a calibration/sensitivity reference standard by all parties
sible technical committee to effect the reliability of high purity
concerned with the analyses.
titanium analyses.
3.2.3 specimen—a suitably sized piece cut from a reference
1.5 This standard does not purport to address all of the
or test sample, prepared for installation in the GDMS ion
safety concerns, if any, associated with its use. It is the
source, and analyzed.
responsibility of the user of this standard to establish appro-
3.2.4 test sample—material titanium to be analyzed for
priate safety and health practices and determine the applica-
trace metallic impurities by this GDMS method.
bility of regulatory limitations prior to use.
3.2.4.1 Discussion—Generally the test sample is extracted
2. Referenced Documents from a larger batch (lot, casting) of product and is intended to
be representative of the batch.
2.1 ASTM Standards:
E135 Terminology Relating to Analytical Chemistry for
4. Summary of the Test Method
Metals, Ores, and Related Materials
4.1 A specimen is mounted as the cathode in a plasma
E173 Practice for Conducting Interlaboratory Studies of
3 discharge cell. Atoms subsequently sputtered from the speci-
Methods for Chemical Analysis of Metals
men surface are ionized, and then focused as an ion beam
E180 Practice for Determining the Precision of ASTM
through a double-focusing magnetic-sector mass separation
Methods forAnalysis andTesting of Industrial Chemicals
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, or both, is
scanned.
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 Dec. 10, 2002. Published May 2003. Originally
the ion detector alone (detector noise). Portions may be due to
approved in 1996. Last previous edition approved in 1997 as F1710–97.
Annual Book of ASTM Standards, Vol 03.05.
Discontinued. See 1996 Annual Book of ASTM Standards, Vol 03.05.
4 5
Annual Book of ASTM Standards, Vol 15.05. Annual Book of ASTM Standards, Vol 14.02.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F 1710–97 (2002)
incompletelymassresolvedionsofanisotopeormoleculewith 7. Reagents and Materials
mass close to, but not identical with, M. In all such instances
i
7.1 Reagent and High Purity Grade Reagents, as required
the interfering contributions must be estimated and subtracted
(MeOH, HNO,HF,H O ).
3 2 2
from the measured signal.
7.2 Demineralized Water.
4.2.1 If the source of interfering contributions to the mea-
7.3 Tantalum Reference Sample.
sured ion current at M cannot be determined unambiguously,
i 7.4 Titanium Reference Sample.
the measured current less the interfering contributions from
7.4.1 To the extent available, titanium reference materials
identified sources constitutes an upper bound of the detection
shall be used to produce the GDMS relative sensitivity factors
limit for the current due to the isotope.
for the various elements being determined (Table 1).
4.3 The composition of the test specimen is calculated from
7.4.2 Asnecessary,non-titaniumreferencematerialsmaybe
the mass spectrum by applying a relative sensitivity factor
used to produce the GDMS relative sensitivity factors for the
(RSF(X/M)) for each contaminant element, X, compared to the
various elements being determined.
matrixelement, M. RSF’saredeterminedinaseparateanalysis
7.4.3 Reference materials should be homogeneous and free
of a reference material performed under the same analytical
of cracks or porosity.
conditions, source configuration, and operating protocol as for
7.4.4 At least two reference materials are required to estab-
the test specimen.
lish the relative sensitivity factors, including one nominally
4.4 The relative concentrations of elements X and Y are
99.999% pure (5N-grade) or better titanium metal to establish
calculatedfromtherelativeisotopicioncurrents I(X)and I(Y)
the background contribution in analyses.
i j
in the mass spectrum, adjusted for the appropriate isotopic
7.4.5 The concentration of each analyte for relative sensi-
abundancefactors (A(X), A(Y))and RSF’s. I(X)and I(Y)refer
tivity factor determination should be a factor of 100 greater
i j i j
to the measured ion current from isotopes X and Y, respec-
than the detection limit determined using a nominally
i j
tively, of atomic species X and Y as follows:
99.999%pure(5N-grade)orbettertitaniumspecimen,butless
than 100 ppmw.
@X#/@Y# 5 RSF~X/M!/RSF~Y/M!3 A~Y !/A~X ! 3 I~X !/I~Y !, (1)
j i i j
7.4.6 To meet expected analysis precision, it is necessary
where (X)/(Y) is the concentration ratio of atomic species X
that specimens of reference and test material present the same
to species Y. If species Y is taken to be the titanium matrix
size and configuration (shape and exposed length) in the glow
(RSF(M/M) =1.0), (X) is (with only very small error for pure
discharge ion source, with a tolerance of 0.2 mm in diameter
metal matrices) the absolute impurity concentration of X.
and 0.5 mm in the distance of specimen to cell ion exit slit.
5. Significance and Use
8. Preparation of Reference Standards and Test
Specimens
5.1 This test method is intended for application in the
semiconductor industry for evaluating the purity of materials
8.1 The surface of the parent material must not be included
(for example, sputtering targets, evaporation sources) used in in the specimen.
thin film metallization processes. This test method may be
8.2 The machined surface of the specimen must be cleaned
usefulinadditionalapplications,notenvisionedbytherespon- by chemical etching immediately prior to mounting the speci-
sible technical committee, as agreed upon between the parties
men and inserting it into the glow discharge ion source.
concerned. 8.2.1 Inordertoobtainarepresentativebulkcompositionin
5.2 This test method is intended for use by GDMS analysts a reasonable analysis time, surface cleaning must remove all
invariouslaboratoriesforunifyingtheprotocolandparameters contaminantswithoutalteringthecompositionofthespecimen
fordeterminingtraceimpuritiesinpuretitanium.Theobjective surface.
is to improve laboratory to laboratory agreement of analysis 8.2.2 To minimize the possibility of contamination, clean
eachspecimenseparatelyimmediatelypriortomountinginthe
data. This test method is also directed to the users of GDMS
analyses as an aid to understanding the determination method, glow discharge ion source.
8.2.3 Prepare and use etching solutions in a clean container
and the significance and reliability of reported GDMS data.
insoluble in the contained solution.
5.3 For most metallic species the detection limit for routine
8.2.4 Useful etching solutions are HNO :HF::3:1 or
analysis is on the order of 0.01 weight ppm. With special
HNO :HF:H O : :1:1:1 or H O:HNO :HF:H O ::20:5:5:4
precautions detection limits to sub-ppb levels are possible.
3 2 2 2 3 2 2
(double etched), etching until smooth, clean metal is exposed
5.4 This test method may be used as a referee method for
over the entire surface.
producers and users of electronic-grade titanium materials.
8.2.5 Immediately after cleaning, wash the specimen with
high purity rinses and thoroughly dry the specimen in the
6. Apparatus
laboratory environment.
6.1 Glow Discharge Mass Spectrometer, with mass resolu-
NOTE 1—Examplesofacceptablehighpurityrinsesareverylargescale
tion greater than 3500, and associated equipment and supplies.
integration (VLSI) grade methanol and distilled water.
The GDMS must be fitted with a liquid nitrogencooled
ion-source specimen cell.
8.3 Immediately mount and insert the specimen into the
6.2 Machining Apparatus, capable of preparing specimens glow discharge ion source, minimizing exposure of the
and reference samples in the required geometry and with cleaned, rinsed, specimen surface to the laboratory environ-
smooth surfaces. ment.
F 1710–97 (2002)
TABLE 1 Suite of Impurity Elements to be Analyzed, with
8.3.1 As necessary, use a noncontacting gage when mount-
Appropriate Isotope Selection
ing specimens in the analysis cell specimen holder to ensure
the proper sample configuration in the glow discharge cell (see
NOTE 1—Establish RSFs for the following suite of elements, using the
indicated isotopes for establishing RSF values and for performing
7.4.6).
analyses of test specimens.
8.4 Sputter etch the specimen surface in the glow discharge
NOTE 2—This selection of isotopes minimizes significant interferences
plasma for a period of time before data acquisition (12.3) to
(see Annex A1.). Additional species may be determined and reported, as
ensure the cleanliness of the surface. Pre-analysis sputtering
agreeduponbyallpartiesconcernedwiththeanalyses.Otherisotopescan
conditions can be limited by the need to maintain sample
be selected to assist mass spectrum peak identification or for other
integrity. If sputter cleaning and analysis are carried out under
purposes.
differentplasmaconditions,accuracyshouldbeestablishedfor
Lithium Li
Beryllium Be the analytical protocol adopted and elements measured.
Boron B
Carbon C
9. Preparation of the GDMS Apparatus
Nitrogen N
Oxygen O
19 9.1 The ultimate background pressure in the ion source
Fluorine F
−6
Sodium Na
chamber should be less than 1 310 torr before operation.
Magnesium Mg
The background pressure in the mass analyzer should be less
Aluminum Al
−7
than 5 310 torr during operation.
Silicon Si
Phophorus P
9.2 The glow discharge ion source must be cooled to near
Sulfur S
liquid nitrogen temperature.
Chlorine Cl
Potassium K 9.3 The GDMS instrument must be accurately mass cali-
Calcium Ca
brated prior to measurements.
Scandium Sc
9.4 The GDMS instrument must be adjusted to the appro-
Titanium Ti
Vanadium V
priate mass peak shape and mass resolving power for the
Chromium Cr
required analysis.
Manganese Mn
Iron Fe
9.5 Iftheinstrumentusesdifferentioncollectorstomeasure
Cobalt Co
ion currents during the same analysis, the measurement effi-
Nickel Ni
ciency of each detector relative to the others should be
Copper Cu
66 68
Zinc Zn or Zn
determined at least weekly.
69 71
Gallium Ga or Ga
70 73 9.5.1 If both Faraday cup collector for ion current measure-
Germanium Ge or Ge
ment and ion counting detectors are used during the same
Arsenic As
Selenium Se
analysis, the ion counting efficiency (ICE) must be determined
Bromine Br
85 prior to each campaign of specimen analyses using the follow-
Rubidium Rb
Yttrium Y ing or equivalent procedures:
Zirconium Zr
9.5.1.1 Using a specimen of tantalum, measure the ion
Niobium Nb
current from the major isotope ( Ta) using the ion current
Molybdenum Mo
Ruthenium Ru
Faraday cup detector, and measure the ion current from the
Rhodium Rh 180
minorisotope( Ta)usingtheioncountingdetector,withcare
Silver Ag
106 108
to avoid ion counting losses due to ion-counting system dead
Palladium Pd or Pd
Cadmium Cd
times. The counting loss should be 1% or less.
Indium In
117 119 9.5.1.2 The ion counting efficiency is calculated by multi-
Tin Sn or Sn
180 181
Antimony Sb
plying the ratio of the Ta ion current to the Ta ion current
Iodine I 181 180
by the Ta/ Ta isotopic ratio. The result of this calculation
125 130
Tellurium Te or Te
is the ion counting detector efficiency (ICE).
Cesium Cs
Barium Ba
9.5.1.3 Apply the ICE as a correction to all ion current
Lanthanum La
140 measurements from the ion counting detector obtained in
Cerium Ce
Neodymium Nd analyses by dividing the ion current by the ICE factor.
176 178
Hafnium Hf or Hf
Tantalum Ta
10. Instrument Quality Control
Tungsten W
Rhenium Re
10.1 A well-characterized specimen must be run on a
190 192
Osmium Os or Os
Iridium Ir regular basis to demonstrate the capability of the GDMS
194 196
Platinum Pt or Pt
system as a whole for the required analyses.
Gold Au
201 202
10.2 A recommended procedure is the measurement of the
Hg or Hg
Mercury
Thallium Tl
relative ion currents of selected analytes and the matrix
Lead Pb
element in titanium or tantalum reference samples.
Bismuth Bi
Thorium Th 10.3 Plotvalidationanalysisdatafrom
...