1、 Reference number ISO 17331:2004(E) ISO 2004INTERNATIONAL STANDARD ISO 17331 First edition 2004-05-15 Surface chemical analysis Chemical methods for the collection of elements from the surface of silicon-wafer working reference materials and their determination by total-reflection X-ray fluorescence
2、 (TXRF) spectroscopy Analyse chimique des surfaces Mthodes chimiques pour collecter les lments analyss de tranches de silicium comme matriaux de rfrence pour lanalyse par spectroscopie de fluorescence X en rflexion totale (TXRF) ISO 17331:2004(E) PDF disclaimer This PDF file may contain embedded typ
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7、ale 56 CH-1211 Geneva 20 Tel. + 41 22 749 01 11 Fax + 41 22 749 09 47 E-mail copyrightiso.org Web www.iso.org Published in Switzerland ii ISO 2004 All rights reservedISO 17331:2004(E) ISO 2004 All rights reserved iiiContents Page Foreword iv Introduction v 1 Scope 1 2 Normative references. 1 3 Terms
8、 and definitions. 1 4 Abbreviations 2 5 Reagents 2 6 Apparatus. 6 7 Specimen preparation and measurement environments 6 8 Preparation of calibration specimen. 6 9 Making calibration curve 8 10 Collection of iron and/or nickel from working reference material . 10 11 Determination of iron and/or nicke
9、l of working reference material. 11 12 Precision 11 13 Test report 12 Annex A (informative) International inter-laboratory test results 13 Annex B (informative) International inter-laboratory test results of GF-AAS and ICP-MS . 16 ISO 17331:2004(E) iv ISO 2004 All rights reservedForeword ISO (the In
10、ternational Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing International Standards is normally carried out through ISO technical committees. Each member body interested in a subject for which a technical committee h
11、as been established has the right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical Commission (IEC) on all matters of electrotechnical
12、 standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 2. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circulated to the member bodi
13、es for voting. Publication as an International Standard requires approval by at least 75 % of the member bodies casting a vote. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights (see Note to 10.1). ISO shall not be held responsible f
14、or identifying any or all such patent rights. ISO 17331 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis. ISO 17331:2004(E) ISO 2004 All rights reserved vIntroduction The measurement of metal impurities on the surface of silicon wafers by total-reflection X-ray fluorescence
15、spectroscopy (TXRF) is commonly accepted by the semiconductor industry. ISO 14706 specifies a TXRF method for the measurement of metal impurities on a silicon-wafer surface with atomic surface densities from 1 10 10atoms/cm 2to 1 10 14atoms/cm 2 , also a vapour-phase decomposition (VPD) method for a
16、tomic surface densities from 5 10 8atoms/cm 2to 5 10 12atoms/cm 2 . In ultra-large-scale integrated circuit (ULSI) manufacturing, the measurement of very-low-level metal impurities on the surface of a silicon wafer, less than 10 10atoms/cm 2 , is currently required. Reference materials with low-leve
17、l metal impurities are important in TXRF analysis (see ISO 14706), but the reference materials have a limited shelf life, especially as regards surface contamination. As a result, preparation methods for working reference materials need to be standardized. This test method allows the calculation of
18、metal impurities on the surface of reference and test wafers. Interlaboratory trials in nine laboratories in different countries indicated that this method has good reproducibility and repeatability. INTERNATIONAL STANDARD ISO 17331:2004(E) ISO 2004 All rights reserved 1Surface chemical analysis Che
19、mical methods for the collection of elements from the surface of silicon-wafer working reference materials and their determination by total-reflection X-ray fluorescence (TXRF) spectroscopy 1 Scope This International Standard specifies chemical methods for the collection of iron and/or nickel from t
20、he surface of silicon-wafer working reference materials by the vapour-phase decomposition method or the direct acid droplet decomposition method. NOTE The determination of the elements collected may be carried out by graphite-furnace atomic-absorption spectroscopy or inductively coupled plasma mass
21、spectrometry instead of by total-reflection X-ray fluorescence spectroscopy. This International Standard applies to iron and/or nickel atomic surface densities from 6 10 9atoms/cm 2to 5 10 11atoms/cm 2 . 2 Normative references The following referenced documents are indispensable for the application
22、of this document. For dated references, only the edition cited applies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 5725-2:1994, Accuracy (trueness and precision) of measurement methods and results Part 2: Basic method for the determi
23、nation of repeatability and reproducibility of a standard measurement method ISO 14644-1:1999, Cleanrooms and associated controlled environments Part 1: Classification of air cleanliness ISO 14706:2000, Surface chemical analysis Determination of surface elemental contamination on silicon wafers by t
24、otal-reflection X-ray fluorescence (TXRF) spectroscopy 3 Terms and definitions For the purposes of this document, the following terms and definitions apply. 3.1 working reference material silicon wafer used for the calibration specified in ISO 14706 3.2 calibration specimen silicon wafer with a know
25、n amount of iron and/or nickel in a dried residue, used for calibration purposes ISO 17331:2004(E) 2 ISO 2004 All rights reserved3.3 calibration solution solution used to make a calibration specimen 3.4 internal standard known amount of vanadium or scandium used to normalize the variation in the flu
26、orescence X-ray intensities of iron and/or nickel in a residue 3.5 internal-standard solution solution used to make an internal standard 3.6 scanning rolling a VPD or DADD microdroplet on a hydrophobic silicon surface in a reproducible pattern to cover the entire surface of the wafer 4 Abbreviations
27、 For the purposes of this document, the following abbreviations apply: TXRF total-reflection X-ray fluorescence spectroscopy VPD vapour-phase decomposition DADD direct acid droplet decomposition PE polyethylene PFA polyfluoroalkoxyethylene PP polypropylene PTFE polytetrafluoroethylene GF-AAS graphit
28、e furnace atomic absorption spectroscopy ICP-MS inductively coupled plasma mass spectroscopy 5 Reagents WARNING Hydrofluoric acid is a highly corrosive liquid which attacks glass and has a great affinity for water. Its vapour is irritant and toxic. Its action on the skin and eyes is strongly corrosi
29、ve, producing severe and painful burns which may not be immediately evident and which respond slowly to treatment. All specimens shall be handled in a well-ventilated area. Rubber gloves, rubber boots and a gown of a suitable size to give adequate protection to the individual, as well as full head a
30、nd face protection, shall be worn when handling materials. In an event of contact or suspected contact with hydrofluoric acid, wash the affected area with copious quantities of water and seek immediate medical attention. Consult the manufactures literature for further information. ISO 17331:2004(E)
31、ISO 2004 All rights reserved 35.1 Ultra-pure water, containing less than 1 pg/ml of each of the impurities iron, nickel, vanadium and scandium. 5.2 Ultra-pure hydrofluoric acid, concentration ca. 21 mol/l to ca. 29 mol/l and containing less than 10 pg/ml of each of the impurities iron, nickel, vanad
32、ium and scandium. NOTE The concentration of commercially available ultra-pure hydrofluoric acid is expressed as a percentage. 21 mol/l hydrofluoric acid corresponds to ca. 38 % and 29 mol/l to ca. 50 %. 5.3 Ultra-pure hydrogen peroxide, concentration ca. 10 mol/l to ca. 12 mol/l and containing less
33、than 10 pg/ml of each of the impurities iron, nickel, vanadium and scandium. NOTE The concentration of commercially available ultra-pure hydrogen peroxide is expressed as a percentage. 10 mol/l hydrogen peroxide corresponds to ca. 30 % and 12 mol/l to ca. 35 %. 5.4 Ultra-pure nitric acid, concentrat
34、ion ca. 11 mol/l to ca. 15 mol/l and containing less than 100 pg/ml of each of the impurities iron, nickel, vanadium and scandium. NOTE The concentration of commercially available ultra-pure nitric acid is expressed as a percentage. 11 mol/l nitric acid corresponds to ca. 55 % and 15 mol/l to ca. 68
35、 %. 5.5 Hydrofluoric acid, concentration ca. 29 mol/l and containing less than 100 pg/ml of each of the impurities iron, nickel, vanadium and scandium. NOTE The concentration of commercially available hydrofluoric acid is expressed as a percentage. 29 mol/l hydrofluoric acid corresponds to ca. 50 %.
36、 The hydrofluoric acid specified in 5.5 is available commercially as “semiconductor” grade. 5.6 Hydrogen peroxide, concentration ca. 10 mol/l and containing less than 100 pg/ml of each of the impurities iron, nickel, vanadium and scandium. NOTE The concentration of commercially available hydrogen pe
37、roxide is expressed as a percentage. 10 mol/l hydrogen peroxide corresponds to ca. 30 %. The hydrogen peroxide specified in 5.6 is available commercially as “semiconductor” grade. 5.7 Standard solutions 5.7.1 Iron standard solution: Use a commercially available 1 000 g/ml iron standard solution spec
38、ified for AAS. 5.7.2 Nickel standard solution: Use a commercially available 1 000 g/ml nickel standard solution specified for AAS. 5.7.3 Vanadium standard solution: Use a commercially available 1 000 g/ml vanadium standard solution specified for AAS. 5.7.4 Scandium standard solution: Use a commercia
39、lly available 1 000 g/ml scandium standard solution specified for AAS. 5.8 Diluted calibration solutions 5.8.1 Diluted iron calibration solution 1: A 10 g/ml iron calibration solution in nitric acid. Prepare diluted iron calibration solution 1 by either method a) or b) below: a) Transfer 1 000 l of
40、iron standard solution (5.7.1) to a plastic 100 ml one-mark volumetric flask (6.1) with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca.1 ml of ultra-pure nitric acid (5.4) and finally make up to the mark with ultra-pure water (5.1) and mix. ISO 17331:2004(E) 4 ISO
41、 2004 All rights reservedb) Weigh a 100 ml plastic beaker (6.3) to the nearest 0,1 g. Transfer 1 000 l of iron standard solution (5.7.1) to the beaker with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nitric acid (5.4) and finally add ultra-p
42、ure water (5.1) to make the mass up to 100 g (plus the mass of the beaker) to the nearest 0,1 g and mix. 5.8.2 Diluted iron calibration solution 2: A 100 ng/ml iron calibration solution in nitric acid. Prepare diluted iron calibration solution 2 by either method a) or b) below: a) Transfer 1 000 l o
43、f diluted iron calibration solution 1 (5.8.1 a) to a plastic 100 ml one-mark volumetric flask (6.1) with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nitric acid (5.4) and finally make up to the mark with ultra-pure water (5.1) and mix. b) We
44、igh a 100 ml plastic beaker (6.3) to the nearest 0,1 g. Transfer 1 000 l of diluted iron calibration solution 1 (5.8.1 b) to the beaker with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nitric acid (5.4) and finally add ultra-pure water (5.1)
45、 to make the mass up to 100 g (plus the mass of the beaker) to the nearest 0,1 g and mix. 5.8.3 Diluted nickel calibration solution 1: A 10 g/ml nickel calibration solution in nitric acid. Prepare diluted nickel calibration solution 1 by either method a) or b) below: a) Transfer 1 000 l of nickel st
46、andard solution (5.7.2) to a 100 ml one-mark volumetric plastic flask (6.1) with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nitric acid (5.4) and finally make up to the mark with ultra-pure water (5.1) and mix. b) Weigh a 100 ml plastic bea
47、ker (6.3) to the nearest 0,1 g. Transfer 1 000 l of the nickel standard solution (5.7.2) to the beaker with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nitric acid (5.4) and finally add ultra-pure water (5.1) to make the mass up to 100 g (pl
48、us the mass of the beaker) to the nearest 0,1 g and mix. 5.8.4 Diluted nickel calibration solution 2: A 100 ng/ml nickel calibration solution in nitric acid. Prepare diluted nickel calibration solution 2 by either method a) or b) below: a) Transfer 1 000 l of diluted nickel calibration solution 1 (5
49、.8.3 a) to a plastic 100 ml one-mark volumetric flask (6.1) with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nitric acid (5.4) and finally make up to the mark with ultra-pure water (5.1) and mix. b) Weigh a 100 ml plastic beaker (6.3) to the nearest 0,1 g. Transfer 1 000 l of diluted nickel calibration solution 1 (5.8.3 b) to the beaker with a plastic micropipette (6.2), add ca. 90 ml of ultra-pure water (5.1), then add ca. 1 ml of ultra-pure nit
