1、Designation: F1593 08 (Reapproved 2016)Standard Test Method forTrace Metallic Impurities in Electronic Grade Aluminum byHigh Mass-Resolution Glow-Discharge Mass Spectrometer1This standard is issued under the fixed designation F1593; the number immediately following the designation indicates the year
2、 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 () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This test method covers measuring the concentrations oft
3、race metallic impurities in high purity aluminum.1.2 This test method pertains to analysis by magnetic-sectorglow discharge mass spectrometer (GDMS).1.3 The aluminum matrix must be 99.9 weight % (3N-grade) pure, or purer, with respect to metallic impurities. Theremust be no major alloy constituent,
4、for example, silicon orcopper, greater than 1000 weight ppm in concentration.1.4 This test method does not include all the informationneeded to complete GDMS analyses. Sophisticated computer-controlled laboratory equipment skillfully used by an experi-enced operator is required to achieve the requir
5、ed 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 respon-sible technical committee to affect the reliability of high purityaluminum analyses.1.5 This sta
6、ndard 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 determine the applica-bility of regulatory limitations prior to use.2. Referenced Documents2.1
7、ASTM Standards:2E135 Terminology Relating to Analytical Chemistry forMetals, Ores, and Related MaterialsE177 Practice for Use of the Terms Precision and Bias inASTM Test MethodsE691 Practice for Conducting an Interlaboratory Study toDetermine the Precision of a Test MethodE1257 Guide for Evaluating
8、Grinding Materials Used forSurface Preparation in Spectrochemical Analysis3. Terminology3.1 Terminology in this test method is consistent withTerminology E135. Required terminology specific to this testmethod and not covered in Terminology E135 is indicatedbelow.3.2 campaigna series of analyses of s
9、imilar specimensperformed in the same manner in one working session, usingone GDMS setup. As a practical matter, cleaning of the ionsource specimen cell is often the boundary event separatingone analysis campaign from the next.3.3 reference sample material accepted as suitable for useas a calibratio
10、n/sensitivity reference standard by all partiesconcerned with the analyses.3.4 specimena suitably sized piece cut from a reference ortest sample, prepared for installation in the GDMS ion source,and analyzed.3.5 test sample material (aluminum) to be analyzed fortrace metallic impurities by this GDMS
11、 test method. Generallythe test sample is extracted from a larger batch (lot, casting) ofproduct and is intended to be representative of the batch.4. Summary of the Test Method4.1 A specimen is mounted as the cathode in a plasmadischarge cell. Atoms subsequently sputtered from the speci-men surface
12、are ionized, and then focused as an ion beamthrough a double-focusing magnetic-sector mass separationapparatus. The mass spectrum, that is, the ion current, iscollected as magnetic field, or acceleration voltage is scanned,or both.4.2 The ion current of an isotope at mass Miis the totalmeasured curr
13、ent, less contributions from all other interferingsources. Portions of the measured current may originate fromthe ion detector alone (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 instancest
14、he interfering contributions must be estimated and subtractedfrom the measured signal.1This test method is under the jurisdiction of ASTM Committee F01 onElectronics and is the direct responsibility of Subcommittee F01.17 on SputterMetallization.Current edition approved May 1, 2016. Published May 20
15、16. Originallyapproved in 1995. Last previous edition approved in 2008 as F1593 08. DOI:10.1520/F1593-08R16.2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the stan
16、dards Document Summary page onthe ASTM website.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States14.2.1 If the source of interfering contributions to the mea-sured ion current at Micannot be determined unambiguously,the measured current
17、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 mass spectrum by applying a relative sensitivity factor(RSF(X/M) for each contaminant element,
18、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 test specimen.4.4 The relative concentrations of elements X and Y arecalculated from the relati
19、ve 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) referto the measured ion current from isotopes Xiand Yj,respectively, of atomic species X and Y.X!/Y! 5 RSFX/M!/RSFY/M! 3AYj!/AXi! 3IXi!/IYi!(
20、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 matrices) the absolute impurity concentration of X.5. Significance and Use5.1 This test method is intended for
21、 application in thesemiconductor industry for evaluating the purity of materials(for example, sputtering targets, evaporation sources) used inthin film metallization processes. This test method may beuseful in additional applications, not envisioned by the respon-sible technical committee, as agreed
22、 upon by 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 pure aluminum. The objec-tive is to improve laboratory to laboratory agreement ofanalysis data. This test method
23、is also directed to the users ofGDMS analyses as an aid to understanding the determinationmethod, and the significance and reliability of reported GDMSdata.5.3 For most metallic species the detection limit for routineanalysis is on the order of 0.01 weight ppm. With specialprecautions detection limi
24、ts to sub-ppb levels are possible.5.4 This test method may be used as a referee method forproducers and users of electronic-grade aluminum materials.6. Apparatus6.1 Glow Discharge Mass Spectrometer, with mass resolu-tion greater than 3500, and associated equipment and supplies.The GDMS must be fitte
25、d with an ion source specimen cell thatis cooled by liquid nitrogen, Peltier cooled, or cooled by anequivalent method.6.2 Machining Apparatus, capable of preparing specimensand reference samples in the required geometry and withsmooth surfaces.6.3 Electropolishing Apparatus, capable of removing thec
26、ontaminants from the surfaces of specimens.7. Reagents and Materials7.1 Reagent and High Purity Grade Reagents, as required(MeOH, HNO3, HCl).7.2 Demineralized Water.7.3 Tantalum Reference Sample.7.4 Aluminum Reference Sample.7.4.1 To the extent available,Aluminum reference materialsshall be used to
27、produce the GDMS relative sensitivity factorsfor the various elements being determined (see Table 1).7.4.2 As necessary, non-aluminum reference materials maybe used to produce the GDMS relative sensitivity factors forthe various elements being determined.7.4.3 Reference materials should be homogeneo
28、us and freeof cracks or porosity.7.4.4 At least two reference materials are required to estab-lish the relative sensitivity factors, including one nominally99.9999 % pure (6N-grade) aluminum metal to establish thebackground contribution in analyses.7.4.5 The concentration of each analyte for relativ
29、e sensi-tivity factor determination should be a factor of 100 greaterthan the detection limit determined using a nominally99.9999 % pure (6N-grade) aluminum specimen, but less than100 ppmw.7.4.6 To meet expected analysis precision, it is necessarythat specimens of reference and test material present
30、 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 specimen to cell ion exit slit.8. Preparation of Reference Standards and TestSpecimens8.1 The surface of the parent material must not be inc
31、ludedin the specimen.TABLE 1 Suite of Impurity Elements to Be AnalyzedANOTE 1Establish RSFs for the following suite of elements.silver arsenic gold boron beryllium calcium cerium chromium cesium copper ironpotassium lithium magnesium manganese sodium nickel phosphorus antimony silicon tin thoriumtit
32、anium uranium vanadium zinc zirconiumAAdditional species may be determined and reported, as agreed upon between all parties concerned with the analyses.F1593 08 (2016)28.2 The machined surface of the specimen must be cleanedby electropolishing or etching immediately prior to mountingthe specimen and
33、 inserting it into the glow discharge ionsource.8.2.1 In order to obtain a representative bulk composition ina reasonable analysis time, surface cleaning must remove allcontaminants without altering the composition of the specimensurface.8.2.2 To minimize the possibility of contamination, cleaneach
34、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.8.2.4 Electropolishing perform electropolishing in a solu-tion of methanol and HNO3mixed in the ratio
35、7:5 by volume.Apply 515 volts (dc) across the cell, with the specimen asanode. Electropolish for up to 4 min, as sufficient to exposesmooth, clean metal over the entire polished surface.8.2.5 Etchingperform etching by immersing the specimenin aqua regia (HNO3and HF, mixed in the ratio 3:1 byvolume).
36、 Etch for several minutes, until smooth, clean metal isexposed over the entire surface.8.2.6 Immediately after cleaning, wash the specimen withseveral rinses of high purity methanol or other high purityreagent to remove water from the specimen surface, and drythe specimen in the laboratory environme
37、nt.8.3 Immediately mount and insert the specimen into theglow discharge ion source, minimizing exposure of thecleaned, rinsed specimen surface to the laboratory environ-ment.8.3.1 As necessary, use a non-contacting gage when mount-ing specimens in the analysis cell specimen holder to ensurethe prope
38、r sample configuration in the glow discharge cell (see7.4.6).8.4 Sputter etch the specimen surface in the glow dischargeplasma for a period of time before data acquisition (see 12.3)to ensure the cleanliness of the surface. Pre-analysis sputteringconditions are limited by the need to maintain sample
39、 integrity.Pre-analysis sputtering at twice the power used for the analysisshould be adequate for sputter etch cleaning.9. Preparation of the GDMS Apparatus9.1 The ultimate background pressure in the ion sourcechamber should be less than 1 106Torr before operation.The background pressure in the mass
40、 analyzer should be lessthan 5 107Torr during operation.9.2 The glow discharge ion source must be cooled to nearliquid nitrogen temperature.9.3 The GDMS instrument must be accurately mass cali-brated prior to measurements.9.4 The GDMS instrument must be adjusted to the appro-priate mass peak shape a
41、nd mass resolving power for therequired analysis.9.5 If the instrument uses different ion collectors to measureion currents during the same analysis, the measurement effi-ciency of each detector relative to the others should bedetermined at least weekly.9.5.1 If both Faraday cup collector for ion cu
42、rrent measure-ment and ion counting detectors are used during the sameanalysis, the ion counting efficiency (ICE) must be determinedprior to each campaign of specimen analyses using the follow-ing or equivalent procedures.9.5.1.1 Using a specimen of tantalum, measure the ioncurrent from the major is
43、otope (181Ta) using the ion currentFaraday cup detector, and measure the ion current from theminor isotope (180Ta) using the ion counting detector, with careto avoid ion counting losses due to ion counting system deadtimes. The counting loss should be 1 % or less.9.5.1.2 The ion counting efficiency
44、is calculated by multi-plying the ratio of the180Ta ion current to the181Ta ion currentby the181Ta/180Ta isotopic ratio. The result of this calculationis the ion counting detector efficiency (ICE).9.5.1.3 Apply the ICE as a correction to all ion currentmeasurements from the ion counting detector obt
45、ained inanalyses by dividing the ion current by the ICE factor.10. Instrument Quality Control10.1 A well-characterized specimen must be run on aregular basis to demonstrate the capability of the GDMSsystem as a whole for the required analyses.10.2 A recommended procedure is the measurement of therel
46、ative ion currents of selected analytes and the matrixelement in aluminum or tantalum reference samples.10.3 Plot validation analysis data from at least five elementswith historic values in statistical process control (SPC) chartformat to demonstrate that the analysis process is in statisticalcontro
47、l. The equipment is suitable for use if the analysis datagroup is within the 3-sigma control limits and shows nonon-random trends.10.4 Upper and lower control limits for SPC must be withinat least 20 % of the mean of previously determined values ofthe relative ion currents.11. Standardization11.1 Th
48、e GDMS instrument should be standardized usingNational Institute of Standards Technology (NIST) traceablereference materials, preferably aluminum, to the extent suchreference samples are available.11.2 Relative sensitivity factor (RSF) values should, in thebest case, be determined from the ion beam
49、ratio measurementsof four randomly selected specimens from each standardrequired, with four independent measurements of each pin.11.3 RSF values must be determined for the suite ofimpurity elements for which specimens are to be analyzed (seeTable 1) using the selected isotopes (see Table 2) for measure-ment and RSF calculation.12. Procedure12.1 Establish a suitable data acquisition protocol (DAP)appropriate for the GDMS instrument used for the analysis.F1593 08 (2016)312.1.1 The DAP must include, but is not limited to, themeasurement of elements tabulated i
