1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationBS ISO 14237:2010Surface chemical analysis Secondary-ion massspectrometry Determinationof boron atomic concentrationin silicon using uniformlydoped materialsBS ISO 14237:2010 BRI
2、TISH STANDARDNational forewordThis British Standard is the UK implementation of ISO 14237:2010. Itsupersedes BS ISO 14237:2000 which is withdrawn.The UK participation in its preparation was entrusted to TechnicalCommittee CII/60, Surface chemical analysis.A list of organizations represented on this
3、committee can beobtained on request to its secretary.This publication does not purport to include all the necessaryprovisions of a contract. Users are responsible for its correctapplication. BSI 2010ISBN 978 0 580 57402 3ICS 71.040.40Compliance with a British Standard cannot confer immunity fromlega
4、l obligations.This British Standard was published under the authority of theStandards Policy and Strategy Committee on 31 August 2010Amendments issued since publicationDate Text affectedBS ISO 14237:2010Reference numberISO 14237:2010(E)ISO 2010INTERNATIONAL STANDARD ISO14237Second edition2010-07-15S
5、urface chemical analysis Secondary-ion mass spectrometry Determination of boron atomic concentration in silicon using uniformly doped materials Analyse chimique des surfaces Spectromtrie de masse des ions secondaires Dosage des atomes de bore dans le silicium laide de matriaux dops uniformment BS IS
6、O 14237:2010ISO 14237:2010(E) PDF disclaimer This PDF file may contain embedded typefaces. In accordance with Adobes licensing policy, this file may be printed or viewed but shall not be edited unless the typefaces which are embedded are licensed to and installed on the computer performing the editi
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9、he address given below. COPYRIGHT PROTECTED DOCUMENT ISO 2010 All rights reserved. Unless otherwise specified, no part of this publication may be reproduced or utilized in any form or by any means, electronic or mechanical, including photocopying and microfilm, without permission in writing from eit
10、her ISO at the address below or ISOs member body in the country of the requester. ISO copyright office Case postale 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 2010 All rights reservedBS ISO 14237:2010ISO 1
11、4237:2010(E) ISO 2010 All rights reserved iiiContents Page Foreword iv Introduction.v 1 Scope1 2 Normative references1 3 Principle1 4 Reference materials 1 4.1 Primary reference material .1 4.2 Secondary reference materials 2 5 Apparatus.2 6 Specimen3 7 Procedure.3 7.1 Adjustment of secondary-ion ma
12、ss spectrometer 3 7.2 Optimizing the secondary-ion mass spectrometer settings.3 7.3 Specimen introduction3 7.4 Detected ions .4 7.5 Calibration4 7.6 Measurement of test specimen6 8 Expression of results6 8.1 Method of calculation6 8.2 Precision.7 9 Test report8 Annex A (informative) Determination of
13、 carrier density in silicon wafer 9 Annex B (informative) Boron isotope ratio measured by SIMS .11 Annex C (normative) Procedures for evaluation of apparatus performance .14 Annex D (informative) Statistical report on interlaboratory test programme .16 Bibliography19 BS ISO 14237:2010ISO 14237:2010(
14、E) iv ISO 2010 All rights reservedForeword ISO (the International 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 int
15、erested in a subject for which a technical committee has 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 Electrotechnic
16、al Commission (IEC) on all matters of electrotechnical 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
17、technical committees are circulated to the member bodies 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.
18、ISO shall not be held responsible for identifying any or all such patent rights. ISO 14237 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee SC 6, Secondary ion mass spectrometry. This second edition cancels and replaces the first edition (ISO 14237:2000), which
19、 has been technically revised. The revision includes, in particular, the replacement of old Annex D concerning procedures for the depth profiling of NIST standard reference material SRM 2137 by references to ISO 17560 and ISO 18114. BS ISO 14237:2010ISO 14237:2010(E) ISO 2010 All rights reserved vIn
20、troduction This International Standard was prepared for the determination by secondary ion mass spectrometry (SIMS) of boron atomic concentrations in uniformly doped silicon wafers. SIMS needs reference materials to perform quantitative analyses. Certified reference materials are only available for
21、limited matrix-impurity combinations, and they are costly. SIMS inevitably consumes these reference materials at every measurement. Thus, secondary reference materials which can be prepared by each laboratory and calibrated using a certified reference material are useful for daily analyses. In this
22、International Standard, a standard procedure is described for boron quantitative analysis in single-crystalline silicon using secondary reference materials calibrated by a certified reference material implanted with boron. BS ISO 14237:2010BS ISO 14237:2010INTERNATIONAL STANDARD ISO 14237:2010(E) IS
23、O 2010 All rights reserved 1Surface chemical analysis Secondary-ion mass spectrometry Determination of boron atomic concentration in silicon using uniformly doped materials 1 Scope This International Standard specifies a secondary-ion mass spectrometric method for the determination of boron atomic c
24、oncentration in single-crystalline silicon using uniformly doped materials calibrated by a certified reference material implanted with boron. This method is applicable to uniformly doped boron in the concentration range from 1 1016atoms/cm3to 1 1020atoms/cm3. 2 Normative references The following ref
25、erenced 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. ISO 17560, Surface chemical analysis Secondary-ion mass spectromet
26、ry Method for depth profiling of boron in silicon ISO 18114, Surface chemical analysis Secondary-ion mass spectrometry Determination of relative sensitivity factors from ion-implanted reference materials 3 Principle An oxygen-ion beam or a caesium-ion beam is impinged onto the sample surface and the
27、 emitted secondary ions of boron and silicon are mass-analysed and detected. Uniformly doped secondary reference materials are calibrated by using an ion-implanted primary reference material and are used as working reference materials. 4 Reference materials 4.1 Primary reference material A primary r
28、eference material is used for the determination of the boron atomic concentration of the secondary reference materials. The primary reference material shall be a certified reference material (CRM) of silicon implanted with boron. NOTE At the time of publication of this International Standard, NIST s
29、tandard reference material SRM 2137 (referred to hereinafter as NIST SRM) was the only ion-implanted CRM of boron in silicon. BS ISO 14237:2010ISO 14237:2010(E) 2 ISO 2010 All rights reserved4.2 Secondary reference materials 4.2.1 Secondary reference materials are used for the determination of boron
30、 atomic concentrations in test specimens. At least one boron-doped reference material together with one non-boron-doped reference material shall be used for daily analysis. Two other different boron-doping levels are recommended to be used to confirm the performance of the apparatus (see Annex C). 4
31、.2.2 The secondary reference materials (referred to hereinafter as bulk RMs) shall be single-crystal silicon wafers or epitaxial silicon wafers with a ca. 100 m thick epitaxial layer, and shall be uniformly doped with natural-isotopic boron. 4.2.3 Boron-doped wafers with boron atomic concentrations
32、between 1 1016atoms/cm3and 1 1020atoms/cm3shall be obtained. It is recommended that the three doping levels given in Table 1 are used. When only one level is used, RM-B or RM-C should be chosen. A non-boron-doped wafer shall be obtained for background checking. Wafers with small boron concentration
33、gradients shall be selected. The boron concentration gradient shall be less than 5 % per cm. NOTE Approximate boron atomic concentrations can be determined as carrier densities from the resistivity of the wafers. The resistivity measurement procedures and the procedure for converting between resisti
34、vity and carrier density are presented in Annex A. Table 1 Bulk reference materials Name Boron doping level atoms/cm3RM-A low 1 1016to 1 1017RM-B middle 5 1017to 5 1018RM-C high 1 1019to 1 1020RM-BG none 100 m2Primary-ion scan area 4 times the analysed area or larger Table 3 Measurement conditions f
35、or caesium-ion beam Element Characteristic Primary-ion species Cs+Secondary-ion polarity Negative Analysed area 100 m2Primary-ion scan area 4 times the analysed area or larger 7.2 Optimizing the secondary-ion mass spectrometer settings 7.2.1 Set the required instrument parameters and align the ion o
36、ptics in accordance with the manufacturers instructions or a local documented procedure. 7.2.2 Ensure the stability of the primary-ion current and the mass spectrometer in accordance with the manufacturers instructions or a local documented procedure. 7.3 Specimen introduction Immediately prior to i
37、ntroducing the specimens into the SIMS apparatus, dust particles shall be removed from the surfaces with a pressurized duster. After introducing the specimens into the analysis chamber, analysis shall not start until the pressure has recovered to the normal value recommended by the manufacturer or a
38、 local documented procedure. Residual gases in the analysis chamber can produce a 10B28Si1Hbackground signal which interferes in 11B28Sidetection, so care should be taken to obtain a better vacuum condition when a caesium-ion beam is used. BS ISO 14237:2010ISO 14237:2010(E) 4 ISO 2010 All rights res
39、erved7.4 Detected ions 7.4.1 When an oxygen-ion beam is used, both 10B+and 11B+shall be detected as secondary-ion species of boron. When a caesium-ion beam is used, both 10B28Siand 11B28Sishall be detected as secondary-ion species of boron. 7.4.2 The ion species of silicon which has an appropriate i
40、on intensity shall be detected, following the manufacturers instructions or a local documented procedure. If the instrument has an electrometer detection mode, it is recommended that 28Si+be detected as the reference ion of B+using the electrometer. For the pulse-counting mode, the silicon-ion inten
41、sity should be less than 1 105counts/s. For BSidetection, Si2is preferable as the reference ion. 7.5 Calibration 7.5.1 Measurement procedure for CRM 7.5.1.1 The depth profile of boron (either 10B or 11B) in the CRM shall be measured using the same conditions as those for the bulk RMs on the same day
42、 as the bulk RM measurements, following the procedures stipulated in ISO 17560. The mean integrated ion intensity ratio of the CRM, Aimp, shall be calculated following the procedures stipulated in ISO 18114. 7.5.1.2 The relative-sensitivity factor of the CRM shall be obtained from the following form
43、ula: impimpRSFA= where RSFimpis the isotopic relative-sensitivity factor obtained from the CRM; is the implanted boron (either 10B or 11B) dose of the CRM. 7.5.2 Measurement procedure for bulk RMs 7.5.2.1 Measurements shall be made from the central region of the specimen holder window. When the boro
44、n-ion intensity of the bulk RM is high, care shall be taken so as not to saturate the detector. If the boron-ion intensity is higher than 1 105counts/s, the primary-ion intensity shall be reduced. 7.5.2.2 Depth profiles of boron and silicon shall be measured for all the bulk RMs. The data sampling d
45、escribed below shall start after any surface contamination is removed and the secondary-ion intensities reach stationary values, but shall be concluded before a change in secondary-ion intensity occurs due to surface roughening induced by ion bombardment. 7.5.2.3 The secondary-ion intensities of bor
46、on and silicon shall be measured for at least 10 cycles alternately, for at least 1 s for each boron isotope per cycle, at the same analysis position. This procedure shall be repeated three times at different positions on the same specimen surface. Then another specimen shall be measured. If the var
47、iation of silicon-ion intensity for one measurement point is less than the value guaranteed by the manufacturer or that determined to be acceptable by local documented procedures, it can be regarded as constant. In this case, it is not necessary to measure the silicon-ion intensity cycle by cycle. I
48、t can be measured at any one cycle for each analysis position. 7.5.2.4 The detected secondary-ion intensity of boron in RM-BG shall be used as the background level of the analysis. BS ISO 14237:2010ISO 14237:2010(E) ISO 2010 All rights reserved 57.5.2.5 Ion intensity ratios of boron to silicon for e
49、ach bulk RM shall be determined for each measurement cycle by cycle at one measurement position, and then a mean value for all the measurement cycles shall be calculated, and the mean value obtained further averaged for three measurement positions, using the following formulae: 11,11,Si,ijijijIJI= 311 11,11113nijjiJJn=where 11,ijI and Si,ijI are the 11B-ion intensity and the silicon-ion intensity in each RM, respectively, at measurement cycle i and measurement position
