1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 12406:2010Surface chemical analysis Secondary-ion massspectrometry Method fordepth profiling of arsenic insiliconBS ISO 12406:2010 BRITISH STANDARDNational forewordThis Br
2、itish Standard is the UK implementation of ISO 12406:2010.The UK participation in its preparation was entrusted to TechnicalCommittee CII/60, Surface chemical analysis.A list of organizations represented on this committee can beobtained on request to its secretary.This publication does not purport t
3、o include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 66874 6ICS 71.040.40Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of theStandards Po
4、licy and Strategy Committee on 30 November 2010.Amendments issued since publicationDate Text affectedBS ISO 12406:2010Reference numberISO 12406:2010(E)ISO 2010INTERNATIONAL STANDARD ISO12406First edition2010-11-15Surface chemical analysis Secondary-ion mass spectrometry Method for depth profiling of
5、 arsenic in silicon Analyse chimique des surfaces Spectromtrie de masse des ions secondaires Dosage de larsenic dans le silicium par profilage dpaisseur BS ISO 12406:2010ISO 12406:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this fi
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10、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 2010 All rights reservedBS ISO 12406:2010ISO 12406:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Terms and defini
11、tions .1 4 Symbols and abbreviated terms 1 5 Principle .2 6 Reference materials 2 6.1 Reference materials for calibration of relative-sensitivity factors .2 6.2 Reference materials for calibration of depth scale2 7 Apparatus.2 7.1 Secondary-ion mass spectrometer .2 7.2 Stylus profilometer2 7.3 Optic
12、al interferometer.3 8 Specimen3 9 Procedures.3 9.1 Adjustment of secondary-ion mass spectrometer 3 9.2 Optimizing the secondary-ion mass spectrometer settings.3 9.3 Specimen introduction4 9.4 Detected ions .4 9.5 Measurement of test specimen4 9.6 Calibration5 10 Expression of results6 11 Test report
13、7 Annex A (informative) Report of round robin test of depth profiling of arsenic in silicon .8 Annex B (normative) Procedures for the depth profiling of NIST SRM 2134 .11 Bibliography13 BS ISO 12406:2010ISO 12406:2010(E) iv ISO 2010 All rights reservedForeword ISO (the International Organization for
14、 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 has been established has the
15、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 standardization. Internatio
16、nal 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 bodies for voting. Publication a
17、s 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. ISO shall not be held responsible for identifying any or all such patent rights. I
18、SO 12406 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee SC 6, Secondary ion mass spectrometry. BS ISO 12406:2010ISO 12406:2010(E) ISO 2010 All rights reserved vIntroduction This International Standard was prepared for the quantitative depth profiling of arsen
19、ic in silicon by secondary-ion mass spectrometry (SIMS). For quantitative depth profiling, calibration is necessary both for the concentration and depth scales of the profile measured. A procedure for the determination of boron atomic concentration in silicon has been established as an International
20、 Standard, ISO 14237. A procedure for depth profiling of boron in silicon has been established as an International Standard, ISO 17560. A procedure for the determination of relative-sensitivity factors (RSFs) from ion-implanted reference materials has been established as an International Standard, I
21、SO 18114. A vocabulary of general terms and terms used for spectroscopy in surface chemical analysis has been established as an International Standard, ISO 18115-1. The procedure for the quantitative depth profiling of arsenic in silicon makes use of these other International Standards. In this Inte
22、rnational Standard, procedures are described for depth profiling of arsenic in single-crystal, poly-crystal or amorphous silicon using SIMS, and for depth scale calibration using stylus profilometry or optical interferometry. BS ISO 12406:2010BS ISO 12406:2010INTERNATIONAL STANDARD ISO 12406:2010(E)
23、 ISO 2010 All rights reserved 1Surface chemical analysis Secondary-ion mass spectrometry Method for depth profiling of arsenic in silicon 1 Scope This International Standard specifies a secondary-ion mass spectrometric method using magnetic-sector or quadrupole mass spectrometers for depth profiling
24、 of arsenic in silicon, and using stylus profilometry or optical interferometry for depth calibration. This method is applicable to single-crystal, poly-crystal or amorphous silicon specimens with arsenic atomic concentrations between 1 g117 1016atoms/cm3and 2,5 g117 1021atoms/cm3, and to crater dep
25、ths of 50 nm or deeper. 2 Normative references The following referenced documents are indispensable for the application 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. IS
26、O 14237:2010, Surface chemical analysis Secondary-ion ma ss spectrometry Determination of boron atomic concentration in silicon using uniformly doped materials ISO 18114:2003, Surface chemical analysis Secondary-ion mass spectrometry Determination of relative sensitivity factors from ion-implanted r
27、eference materials ISO 18115-1, Surface chemical analysis Vocabulary Part 1: General terms and terms used in spectroscopy 3 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 18115-1 apply. 4 Symbols and abbreviated terms Citotal arsenic atomic concentrat
28、ion at measurement cycle, i, expressed in atoms per cubic centimetre (atoms/cm3) d depth over which depth profile is integrated to determine RSF, expressed in centimetres (cm) didepth for measurement cycle, i, expressed in centimetres (cm) dtcrater depth, expressed in centimetres (cm) Iiion intensit
29、y of arsenic species at measurement cycle, i, expressed in counts/s IiSiion intensity of silicon matrix species at measurement cycle, i, expressed in counts/s BS ISO 12406:2010ISO 12406:2010(E) 2 ISO 2010 All rights reservedIBGmean background ion intensity of the arsenic-ion species, expressed in co
30、unts/s Jiion intensity ratio of arsenic to silicon at measurement cycle, i JBGmean background ion intensity ratio of arsenic to silicon n total number of measurement cycles RSFimprelative-sensitivity factor of implanted arsenic in certified reference material (CRM) (cmg163) T total sputtering time,
31、expressed in seconds (s) tiAsstarting time of arsenic-ion acquisition at measurement cycle, i, expressed in seconds (s) g39tAsduration of arsenic-ion acquisition in each measurement cycle, expressed in seconds (s) g41 implanted dose of arsenic in CRM, expressed in atoms per square centimetre (atoms/
32、cm2) 5 Principle A caesium ion beam or oxygen ion beam is scanned over the specimen surface and the emitted secondary ions of arsenic and silicon are mass-analysed and detected from a gated region in the scanned region of the ion beam. The intensities of these mass-analysed signals are monitored as
33、a function of sputtering time. The depth of the crater formed by the ion beam is measured by stylus profilometry or optical interferometry for depth scale calibration. NOTE Optical interferometry is generally applicable to crater depths in the range from 0,2 m to 5 m. 6 Reference materials 6.1 Refer
34、ence materials for calibration of relative-sensitivity factors A reference material is used for the determination of the arsenic atomic concentration of a test specimen. The reference material shall be a CRM of silicon implanted with arsenic or a secondary reference material of ion-implanted arsenic
35、 in silicon, the dose of which is traceable to a CRM. NOTE At the time of publication of this International Standard, NIST standard reference material 2134 (referred to hereinafter as NIST SRM) and NMIJ CRM 5603-a are the only CRMs of arsenic available. 6.2 Reference materials for calibration of dep
36、th scale For stylus profilometry calibration, reference materials that are traceable to the SI system shall be used. 7 Apparatus 7.1 Secondary-ion mass spectrometer Follow the specification and procedures in Clause 5 of ISO 14237:2010. 7.2 Stylus profilometer Use a stylus profilometer with the sensi
37、tivity and tip shape suitable for the crater shapes measured. BS ISO 12406:2010ISO 12406:2010(E) ISO 2010 All rights reserved 37.3 Optical interferometer Use an optical interferometer with the sensitivity and functions suitable for the crater shapes measured. 8 Specimen The specimen shall be cut int
38、o an appropriate size for analysis and degreased and washed, if necessary. NOTE The accuracy of a crater depth measurement is largely influenced by surface roughness. A mirror-polished wafer is preferable if accurate determination of the depth scale is necessary. 9 Procedures 9.1 Adjustment of secon
39、dary-ion mass spectrometer 9.1.1 For caesium-ion beam use, see Table 1. For oxygen-ion beam use, see Table 2. Other conditions not shown in this clause shall be set according to the manufacturers instructions or a local documented procedure. 9.1.2 For the primary-ion beam, the beam current and scan
40、region can be varied from specimen to specimen (see 9.5.2). However, when oxygen-gas is introduced in the chamber during oxygen-beam irradiation, the oxygen pressure and all the primary-ion beam irradiation conditions shall be the same for the measurements of all specimens. Table 1 Measurement condi
41、tions for caesium-ion beam Primary-ion species Cs+Secondary-ion polarity Negative Primary-ion scan region g333 times the linear dimension of the analysed region in all directions Analysed region Centred in the primary-ion scan region Table 2 Measurement conditions for oxygen-ion beam Primary-ion spe
42、cies O2+Secondary-ion polarity PositivePrimary-ion scan region g333 times the linear dimension of the analysed region in all directionsAnalysed region Centred in the primary-ion scan region9.2 Optimizing the secondary-ion mass spectrometer settings 9.2.1 Set the required instrument parameters and al
43、ign the ion optics according to the manufacturers instructions or a local documented procedure. 9.2.2 Ensure the stability of the primary-ion current and the mass spectrometer according to the manufacturers instructions or a local documented procedure. 9.2.3 For a mass spectrometer whose transmissio
44、n can be varied, use the same transmission for the measurements of reference materials and test specimens. BS ISO 12406:2010ISO 12406:2010(E) 4 ISO 2010 All rights reserved9.3 Specimen introduction Immediately prior to introduction of the specimens into the SIMS apparatus, dust particles should be r
45、emoved from the surfaces with a high purity pressurized gas, such as nitrogen. A commercial pressurized duster can also be used, but it may contaminate the sample surface. After introducing the specimens into the analysis chamber, analysis shall not start until the pressure has recovered to the norm
46、al value recommended by the manufacturer or a local documented procedure. NOTE Residual gases in the analysis chamber can produce a 29Si30Si16O background signal, which interferes with the 75Asg114signal. This background can be reduced by improving the vacuum in the analysis chamber. 9.4 Detected io
47、ns 9.4.1 If a caesium-ion beam is used, 75Asg16and/or 75As28Sig16and/or 75As30Sig16shall be detected as secondary-ion species of arsenic. If an oxygen-ion beam is used, 75As+shall be detected as secondary-ion species of arsenic. NOTE When an oxygen-ion beam is used, a 29Si30Si16O background signal i
48、s produced that interferes with the 75Asg114signal. Specimen offset voltage (detection of secondary-ion with high energy) or high mass resolution operation are effective for decreasing the background signal. 9.4.2 The ion species of silicon which has an appropriate ion intensity shall be detected, f
49、ollowing the manufacturers instructions or a local documented procedure. If the instrument has an electrometer detection mode, it is recommended to select 28Sig114as the reference ion for Asg114using the electrometer. If only a pulse-counting detector is available, 30Sig114should be selected as the reference ion for Asg114. For AsSig16detection, either Si2g16or Si3g16are suitable reference ions, as determined in a round-robin study described in Reference 2 and Annex A. A variety of isotopic species with differe
