ASTM F1845-1997(2002) Standard Test Method for Trace Metallic Impurities in Electronic Grade Aluminum-Copper Aluminum-Silicon and Aluminum-Copper-Silicon Alloys by High-Mass-Reduct.pdf

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1、Designation: F 1845 97 (Reapproved 2002)Standard Test Method forTrace Metallic Impurities in Electronic Grade Aluminum-Copper, Aluminum-Silicon, and Aluminum-Copper-SiliconAlloys by High-Mass-Resolution Glow Discharge MassSpectrometer1This standard is issued under the fixed designation F 1845; the n

2、umber immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Sc

3、ope1.1 This test method determines the concentrations of tracemetallic impurities in high purity (99.99 wt. % pure, or purer,with respect to metallic trace impurities) aluminum-copper,aluminum-silicon and aluminum-copper-silicon alloys withmajor alloy constituents as follows:aluminum Greater than 95

4、.0 %copper Less or equal than 5.0 %silicon Less or equal than 5.0 %1.2 This test method pertains to analysis by magnetic-sectorglow discharge mass spectrometer (GDMS).1.3 This test method does not include all the informationneeded to complete GDMS analyses. Sophisticated computer-controlled laborato

5、ry equipment, skillfully used by an experi-enced 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 detection limits, etc.) known by the respon-sible

6、technical committee to effect the reliability of high purityaluminum analyses.1.4 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and deter

7、mine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1 ASTM Standards:E 135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related Materials2E 180 Practice for Determining the Precision of ASTMMethods for Analysis and Testing of Industrial and Sp

8、e-cialty Chemicals3E 673 Terminology Relating to Surface Analysis2E 876 Practice for Use of Statistics in the Evaluation ofSpectrometric DataF 1593 Test Method for Trace Metallic Impurities in Elec-tronic Grade Aluminum by High-Mass-Resolution GlowDischarge Mass Spectrometer4F 1594 Specification for

9、 Pure Aluminum (Unalloyed)Source Material for Vacuum Coating Applications53. Terminology3.1 Terminology in this test method is consistent withTerminology E 135. Required terminology specific to this testmethod, not covered in Terminology E 135, is indicated in 3.2.3.2 Definitions:3.2.1 campaigna tes

10、t procedure to determine the accuracyof the instrument, which was normally performed at thebeginning of the day or after the instrument modification, orboth.3.2.2 reference samplematerial accepted as suitable foruse as a calibration/sensitivity reference standard by all partiesconcerned with the ana

11、lyses.3.2.3 specimena suitably sized piece cut from a referenceor test sample, prepared for installation in the GDMS ionsource, and analyzed.3.2.4 test samplematerial (aluminum alloy) to be ana-lyzed for trace metallic impurities by this GDMS method.3.2.4.1 DiscussionGenerally the test sample is ext

12、ractedfrom a larger batch (lot, casting) of product and is intended tobe representative of the batch.4. Summary of Test Method4.1 A specimen is mounted in a plasma discharge cell.Atoms subsequently sputtered from the specimen surface areionized, and then focused as an ion beam through a double-focus

13、ing magnetic-sector mass separation apparatus. The massspectrum (the ion current) is collected as magnetic field oracceleration voltage, (or both) is scanned.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.17 on Spu

14、tterMetallization.Current edition approved Dec. 10, 2002. Published May 2003. Originallyapproved in 1997. Last previous edition approved in 1997 as F 1845 97.2Annual Book of ASTM Standards, Vol 03.05.3Annual Book of ASTM Standards, Vol 15.05.4Annual Book of ASTM Standards, Vol 10.04.1Copyright ASTM

15、International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959, United States.4.2 The ion current of an isotope at mass Miis the totalmeasured current, less contributions from all other interferingsources. Portions of the measured current may originate fromthe ion detector alone

16、 (detector noise). Portions may be due toincompletely mass resolved ions of an isotope or molecule withmass close to, but not identical with, Mi. In all such instancesthe interfering contributions must be estimated and subtractedfrom the measured signal.4.2.1 If the source of interfering contributio

17、ns to the mea-sured ion current at Micannot be determined unambiguously,the measured current less the interfering contributions fromidentified sources constitutes an upper bound of the detectionlimit for the current due to the isotope.4.3 The composition of the test specimen is calculated fromthe ma

18、ss spectrum by applying a relative sensitivity factor(RSF(X/M) for each contaminant element, X, compared to thematrix element, M. RSFs are determined in a separate analysisof a reference material performed under the same analyticalconditions, source configuration, and operating protocol as forthe te

19、st specimen.4.4 The relative concentrations of elements X and Y arecalculated from the relative isotopic ion currents I (Xi) and I(Yj) in the mass spectrum, adjusted for the appropriate isotopicabundance factors (A (Xi), A (Yj) and RSFs. I (Xi) and I (Yj)refer to the measured ion current from isotop

20、es Xiand Yj,respectively, of atomic species X and Y as follows:X!/Y!5RSFX/M!/RSFY/M!3AYj!/AXi! 3 IXi!/IYj! (1)where (X)/(Y) is the concentration ratio of atomic species Xto species Y. If species Y is taken to be the aluminum matrix(RSF (M/M) = 1.0), (X) is (with only very small error for puremetal m

21、atrices) the absolute impurity concentration of X.5. Significance and Use5.1 This test method is intended for application in thesemiconductor industry for evaluating the purity of materials(for example, sputtering targets, evaporation sources) used inthin film metallization processes. This test meth

22、od may beuseful in additional applications, not envisioned by the respon-sible technical committee, as agreed upon between the partiesconcerned.5.2 This test method is intended for use by GDMS analystsin various laboratories for unifying the protocol and parametersfor determining trace impurities in

23、 aluminum-copper,aluminum-silicon, and aluminum-copper-silicon alloys. Theobjective is to improve laboratory-to-laboratory agreement ofanalysis data. This test method is also directed to the users ofGDMS analyses as an aid to understanding the determinationmethod, and the significance and reliabilit

24、y of reported GDMSdata.5.3 For most metallic species the detection limit for routineanalysis is on the order of 0.01 wt. ppm. With specialprecautions, detection limits to sub-ppb levels are possible.5.4 This test method may be used as a referee method forproducers and users of electronic-grade alumi

25、num-copper,aluminum-silicon and aluminum-copper-silicon materials.6. Apparatus6.1 Glow Discharge Mass Spectrometer, with mass resolu-tion greater than 3500, and associated equipment and supplies.6.2 Machining Apparatus, capable of preparing specimensand reference samples in the desired geometry and

26、with smoothsurfaces.6.3 Electro-Polishing Apparatus, capable of removing thecontaminants from the surfaces of specimens.7. Reagents and Materials7.1 ReagentsReagent and high purity grade reagents asrequired (MeHO, HNO3and HCl)7.2 Demineralized Water.7.3 Tantalum Reference Sample.7.4 Aluminum Referen

27、ce Sample.7.4.1 To the extent available, aluminum reference materialsshall be used to produce the GDMS relative sensitivity factorsfor the various elements being determined (see Table 1).7.4.1.1 As necessary, non-aluminum reference materialsmay be used to produce the GDMS relative sensitivity factor

28、sfor the various elements being determined.7.4.2 Reference materials should be homogeneous (see11.1) and free of cracks or porosity.7.4.3 At least two reference materials are required to estab-lish the relative sensitivity factors, including a 99.9999 % purealuminum metal to establish the background

29、 contribution inanalyses.7.4.4 The concentration of each analyte for relative sensi-tivity factor determination should be at a factor of 100 greaterthan the detection limit determined using a 99.9999 % purealuminum specimen, but less than 100 ppmw.7.4.5 To meet expected analysis precision, it is nec

30、essarythat specimens of reference and test material present the samesize and configuration (shape and exposed length) in the glowdischarge ion source, with a tolerance of 0.2 mm in diameterand 0.5 mm in the distance of sample to cell ion exit slit.8. Preparation of Reference Standards and TestSpecim

31、ens8.1 The surface of the parent material must not be includedin the specimen.TABLE 1 Suite of Impurity Elements to Be AnalyzedANOTEEstablish RSFs for the following suite of elements:silver arsenic gold boron beryllium calcium cerium chromium cesium copper ironpotassium lithium magnesium manganese s

32、odium nickel phosphorus antimony silicon tin thoriumtitanium uranium vanadium zinc zirconiumAAdditional species may be determined and reported, as agreed upon between all parties concerned with the analyses.F 1845 97 (2002)28.2 The machined surface of the specimen must be cleanedby electropolishing

33、or etching immediately prior to mountingthe specimen and inserting it into the glow discharge ionsource.8.2.1 In order to obtain a representative bulk composition ina reasonable analytical time, surface cleaning must remove allcontaminants without altering the composition of the specimensurface.8.2.

34、2 To minimize the possibility of contamination, cleaneach specimen separately immediately prior to mounting in theglow discharge ion source.8.2.3 Prepare and use electropolishing or etching solutionsin a clean container insoluble in the contained solution.8.2.3.1 Electropolishingperform electropolis

35、hing in asuitable electropolishing solution (2:1 MeOH:HNO3was foundapplicable). Apply 5 to 15 V (dc) across the cell, with thespecimen as anode. Electropolish to expose smooth, cleanmetal over the entire polished surface.8.2.3.2 Etchingperform etching by immersing the speci-men in suitable acid mixt

36、ure solution (4:1:1 H2O:HF:HNO3was found applicable). Etch the specimen until smooth, cleanmetal is exposed over the entire surface.8.3 Immediately after cleaning, wash the specimen withseveral rinses of high purity methanol, or other high purityreagent able to remove water from the specimen surface

37、, anddry the specimen in the laboratory environment.8.4 Immediately mount and insert the specimen into theglow discharge ion source, minimizing exposure of thecleaned, rinsed and dried specimen surface to the laboratoryenvironment.8.4.1 As necessary, use a noncontacting gage when mount-ing specimens

38、 in the analysis cell specimen holder to ensurethe proper sample configuration in the glow discharge cell (see7.4.5).8.5 Sputter etch the specimen surface in the glow dischargeplasma for a period of time before data acquisition to ensurethe cleanness of the surface (see 12.3). Pre-analysis sputterin

39、gconditions are limited by the need to maintain sample integrity.Pre-analysis sputtering at twice the power used for analysisshould be adequate for sputter etch cleaning.9. Preparation of the GDMS Apparatus9.1 Reference to Test Method F 1593, Section 9.10. Instrument Quality Control10.1 Reference to

40、 Test Method F 1593, Section 10.11. Standardization11.1 The GDMS instrument should be standardized usingNIST traceable reference materials, preferably aluminum to theextent such reference samples are available.11.1.1 RSF values should, in the best case, be determinedfrom the ion beam ratio measureme

41、nts of four randomlyselected specimens from each standard required, with fourindependent measurements of each pin.11.1.2 RSF values must be determined for the suite ofimpurity elements for which specimens are to be analyzed (seeTable 1) using selected isotopes for measurement and RSFcalculation (see

42、 Table 2).12. Analysis Procedure12.1 Establish a suitable data acquisition protocol (DAP)appropriate for the GDMS instrument used for the analysis.12.1.1 The protocol must include, but is not limited to, themeasurement of elements tabulated in Table 1 and isotopestabulated in Table 2 for respective

43、matrix. Annex A1 listssignificant spectral interferences in this testing.12.1.2 Instrumental parameters selected for isotope mea-surements must be appropriate for the analysis requirements:(a) ion current integration times to achieve desired precisionand detection limits; (b) mass ranges about the a

44、nalyte masspeak over which measurements are acquired to clarify massinterferences.12.2 Insert the prepared specimen into the GDMS ionsource, allow the specimen to cool to source temperature, andinitiate the glow discharge at pre-analysis sputtering condi-tions.12.3 After at least 5 min of pre-analys

45、is sputtering, adjustthe glow discharge ion source sputtering conditions to theconditions required for analysis, ensuring that the gas pressurerequired to do so is within normal range.12.4 Analyze the specimen using the DAP protocol andaccept as final the concentration values determined only asdetec

46、tion limits.12.5 Generate a MDAP protocol including only the ele-ments determined to be present in the sample (from results of12.4).TABLE 2 Isotope SelectionANOTEUse the following isotopes for establishing RSF values and forperforming analyses on test specimens.Aluminum-Copper Aluminum-SiliconAlumin

47、um-Copper-SiliconSilver 109 109 109Arsenic 75 75 75Gold 197 197 197Boron 11 11 11Beryllium 9 9 9Calcium 44 44 44Cerium 140 140 140Chromium 52 52 52Cesium 133 133 133Copper 65 65 65Iron 56 56 56Potassium 39 39 39Lithium 7 7 7Magnesium 24 24 24Manganese 55 55 55Sodium 23 23 23Nickel 58 60 60Phosphorus

48、 31 31 31Antimony 208 208 208Silicon 28 28 28Tin 124 119 124Thorium 232 232 232Titanium 48 48 48Uranium 238 238 238Vanadium 51 51 51Zinc 66 66 66Zirconium 94 90 94AThis selection of isotopes minimizes significant interferences. Additionalspecies may be determined and reported, as agreed upon between

49、 all partiesconcerned with the analyses.F 1845 97 (2002)312.6 Measure the sample at least two additional times (withat least 10-min intervals between the measurements) using theMDAP protocol until the criteria of 12.6.1 is met.12.6.1 If the concentration differences between the last twomeasurements are less than 5, 10 or 20 %, depending onconcentration (Table 3), the measurements are confirmed andthe last two measurements are averaged.12.7 The confirmed values from 12.6 and the detectionlimits determined from 12.4 are reported together as the resultof the analysi