ASTM F1845-97(2002)

NOTICE: This standard has either been superseded and replaced by a new version or withdrawn.
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Designation:F1845–97 (Reapproved 2002)
Standard Test Method for
Trace Metallic Impurities in Electronic Grade Aluminum-
Copper, Aluminum-Silicon, and Aluminum-Copper-Silicon
Alloys by High-Mass-Resolution Glow Discharge Mass
Spectrometer
This standard is issued under the fixed designation F 1845; 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 (e) indicates an editorial change since the last revision or reapproval.
1. Scope E 673 Terminology Relating to Surface Analysis
E 876 Practice for Use of Statistics in the Evaluation of
1.1 This test method determines the concentrations of trace
Spectrometric Data
metallic impurities in high purity (99.99 wt. % pure, or purer,
F 1593 Test Method for Trace Metallic Impurities in Elec-
with respect to metallic trace impurities) aluminum-copper,
tronic Grade Aluminum by High-Mass-Resolution Glow
aluminum-silicon and aluminum-copper-silicon alloys with
Discharge Mass Spectrometer
major alloy constituents as follows:
F 1594 Specification for Pure Aluminum (Unalloyed)
aluminum Greater than 95.0 %
Source Material for Vacuum Coating Applications
copper Less or equal than 5.0 %
silicon Less or equal than 5.0 %
3. Terminology
1.2 This test method pertains to analysis by magnetic-sector
3.1 Terminology in this test method is consistent with
glow discharge mass spectrometer (GDMS).
Terminology E 135. Required terminology specific to this test
1.3 This test method does not include all the information
method, not covered in Terminology E 135, is indicated in 3.2.
needed to complete GDMS analyses. Sophisticated computer-
3.2 Definitions:
controlled laboratory equipment, skillfully used by an experi-
3.2.1 campaign—atestproceduretodeterminetheaccuracy
enced operator, is required to achieve the required sensitivity.
of the instrument, which was normally performed at the
Thistestmethoddoescovertheparticularfactors(forexample,
beginning of the day or after the instrument modification, or
specimen preparation, setting of relative sensitivity factors,
both.
determination of detection limits, etc.) known by the respon-
3.2.2 reference sample—material accepted as suitable for
sible technical committee to effect the reliability of high purity
use as a calibration/sensitivity reference standard by all parties
aluminum analyses.
concerned with the analyses.
1.4 This standard does not purport to address all of the
3.2.3 specimen—a suitably sized piece cut from a reference
safety concerns, if any, associated with its use. It is the
or test sample, prepared for installation in the GDMS ion
responsibility of the user of this standard to establish appro-
source, and analyzed.
priate safety and health practices and determine the applica-
3.2.4 test sample—material (aluminum alloy) to be ana-
bility of regulatory limitations prior to use.
lyzed for trace metallic impurities by this GDMS method.
2. Referenced Documents
3.2.4.1 Discussion—Generally the test sample is extracted
from a larger batch (lot, casting) of product and is intended to
2.1 ASTM Standards:
be representative of the batch.
E 135 Terminology Relating to Analytical Chemistry for
Metals, Ores, and Related Materials
4. Summary of Test Method
E 180 Practice for Determining the Precision of ASTM
4.1 A specimen is mounted in a plasma discharge cell.
Methods for Analysis and Testing of Industrial and Spe-
Atoms subsequently sputtered from the specimen surface are
cialty Chemicals
ionized, and then focused as an ion beam through a double-
focusing magnetic-sector mass separation apparatus. The mass
This test method is under the jurisdiction of ASTM Committee F01 on
spectrum (the ion current) is collected as magnetic field or
Electronics and is the direct responsibility of Subcommittee F01.17 on Sputter
acceleration voltage, (or both) is scanned.
Metallization.
Current edition approved Dec. 10, 2002. Published May 2003. Originally
approved in 1997. Last previous edition approved in 1997 as F 1845 – 97.
Annual Book of ASTM Standards, Vol 03.05.
3 4
Annual Book of ASTM Standards, Vol 15.05. Annual Book of ASTM Standards, Vol 10.04.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.
F1845–97 (2002)
4.2 The ion current of an isotope at mass M is the total 5.3 For most metallic species the detection limit for routine
i
measured current, less contributions from all other interfering analysis is on the order of 0.01 wt. ppm. With special
sources. Portions of the measured current may originate from precautions, detection limits to sub-ppb levels are possible.
the ion detector alone (detector noise). Portions may be due to
5.4 This test method may be used as a referee method for
incompletelymassresolvedionsofanisotopeormoleculewith
producers and users of electronic-grade aluminum-copper,
mass close to, but not identical with, M. In all such instances
aluminum-silicon and aluminum-copper-silicon materials.
i
the interfering contributions must be estimated and subtracted
from the measured signal.
6. Apparatus
4.2.1 If the source of interfering contributions to the mea-
6.1 Glow Discharge Mass Spectrometer, with mass resolu-
sured ion current at M cannot be determined unambiguously,
i
tion greater than 3500, and associated equipment and supplies.
the measured current less the interfering contributions from
6.2 Machining Apparatus, capable of preparing specimens
identified sources constitutes an upper bound of the detection
andreferencesamplesinthedesiredgeometryandwithsmooth
limit for the current due to the isotope.
surfaces.
4.3 The composition of the test specimen is calculated from
6.3 Electro-Polishing Apparatus, capable of removing the
the mass spectrum by applying a relative sensitivity factor
contaminants from the surfaces of specimens.
(RSF(X/M)) for each contaminant element, X, compared to the
matrix element, M. RSF’s are determined in a separate analysis
7. Reagents and Materials
of a reference material performed under the same analytical
7.1 Reagents—Reagent and high purity grade reagents as
conditions, source configuration, and operating protocol as for
required (MeHO, HNO and HCl.)
the test specimen.
7.2 Demineralized Water.
4.4 The relative concentrations of elements X and Y are
calculated from the relative isotopic ion currents I (X) and I 7.3 Tantalum Reference Sample.
i
(Y) in the mass spectrum, adjusted for the appropriate isotopic
j 7.4 Aluminum Reference Sample.
abundance factors (A (X), A (Y) and RSF’s. I (X) and I (Y)
i j i j
7.4.1 To the extent available, aluminum reference materials
refer to the measured ion current from isotopes X and Y,
i j
shall be used to produce the GDMS relative sensitivity factors
respectively, of atomic species X and Y as follows:
for the various elements being determined (see Table 1).
~X!/~Y!5 RSF~X/M!/RSF~Y/M!3 A~Y !/A~X ! 3 I~X !/I~Y ! (1)
7.4.1.1 As necessary, non-aluminum reference materials
j i i j
may be used to produce the GDMS relative sensitivity factors
where (X)/(Y) is the concentration ratio of atomic species X
for the various elements being determined.
to species Y. If species Y is taken to be the aluminum matrix
7.4.2 Reference materials should be homogeneous (see
(RSF (M/M) = 1.0), (X) is (with only very small error for pure
11.1) and free of cracks or porosity.
metal matrices) the absolute impurity concentration of X.
7.4.3 At least two reference materials are required to estab-
lish the relative sensitivity factors, including a 99.9999 % pure
5. Significance and Use
aluminum metal to establish the background contribution in
5.1 This test method is intended for application in the
analyses.
semiconductor industry for evaluating the purity of materials
7.4.4 The concentration of each analyte for relative sensi-
(for example, sputtering targets, evaporation sources) used in
tivity factor determination should be at a factor of 100 greater
thin film metallization processes. This test method may be
than the detection limit determined using a 99.9999 % pure
useful in additional applications, not envisioned by the respon-
aluminum specimen, but less than 100 ppmw.
sible technical committee, as agreed upon between the parties
7.4.5 To meet expected analysis precision, it is necessary
concerned.
that specimens of reference and test material present the same
5.2 This test method is intended for use by GDMS analysts
size and configuration (shape and exposed length) in the glow
invariouslaboratoriesforunifyingtheprotocolandparameters
discharge ion source, with a tolerance of 0.2 mm in diameter
for determining trace impurities in aluminum-copper,
and 0.5 mm in the distance of sample to cell ion exit slit.
aluminum-silicon, and aluminum-copper-silicon alloys. The
objective is to improve laboratory-to-laboratory agreement of
8. Preparation of Reference Standards and Test
analysis data. This test method is also directed to the users of
Specimens
GDMS analyses as an aid to understanding the determination
method, and the significance and reliability of reported GDMS 8.1 The surface of the parent material must not be included
data. in the specimen.
A
TABLE 1 Suite of Impurity Elements to Be Analyzed
NOTE—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 bet
...