1、BRITISH STANDARD BS ISO 20341:2003 Surface chemical analysis Secondary-ion mass spectrometry Method for estimating depth resolution parameters with multiple delta-layer reference materials ICS 71.040.40 BS ISO 20341:2003 This British Standard was published under the authority of the Standards Policy
2、 and Strategy Committee on 8 August 2003 BSI 8 August 2003 ISBN 0 580 42439 1 National foreword This British Standard reproduces verbatim ISO 20341:2003 and implements it as the UK national standard. The UK participation in its preparation was entrusted to Technical Committee CII/60, Surface chemica
3、l analysis, which has the responsibility to: A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international publications referred to in this document may be found in the BSI Catalogue under the s
4、ection entitled “International Standards Correspondence Index”, or by using the “Search” facility of the BSI Electronic Catalogue or of British Standards Online. This publication does not purport to include all the necessary provisions of a contract. Users are responsible for its correct application
5、. Compliance with a British Standard does not of itself confer immunity from legal obligations. aid enquirers to understand the text; present to the responsible international/European committee any enquiries on the interpretation, or proposals for change, and keep the UK interests informed; monitor
6、related international and European developments and promulgate them in the UK. Summary of pages This document comprises a front cover, an inside front cover, the ISO title page, pages ii to v, a blank page, pages 1 to 5 and a back cover. The BSI copyright notice displayed in this document indicates
7、when the document was last issued. Amendments issued since publication Amd. No. Date CommentsINTERNATIONAL STANDARD ISO 20341 First edition 2003-07-15 Reference number ISO 20341:2003(E) OSI 2003 Surface chemical analysis Secondary- ion mass spectrometry Method for estimating depth resolution paramet
8、ers with multiple delta-layer reference materials Analyse chimique des surfaces Spectromtrie de masse des ions secondaires Mthode destimation des paramtres de rsolution en profondeur laide de matriaux de rfrence multicouches mincesBSISO20341:2003ISO :14302(3002)E ii ISO 3002 All rithgs reresvde id F
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14、 for multiple delta-layer reference materials 1 5 Procedures . 2 6 Test report 3 Annex A (normative) Simpler options of estimating SIMS depth resolution parameters . 4 Bibliography . 5 BSISO20341:2003ISO :14302(3002)E iv ISO 3002 All rithgs reresvde Foreword ISO (the International Organization for S
15、tandardization) 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 ri
16、ght 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. Internationa
17、l 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 as
18、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. ISO
19、 20341 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee SC 6, Secondary ion mass spectrometry. BSISO20341:2003ISO 43023002:1)E( ISO 3002 r llAithgs reservde v Introduction Depth resolution is one of the important parameters in SIMS depth profiling. However, spu
20、tter depth profiles in SIMS analysis are affected by many factors which may include ion-beam-induced mixing and segregation, charge-driven diffusion, matrix effects, crater shape, surface microtopography, etc. To obtain the best depth resolution, the deterioration of the depth resolution due to thes
21、e factors should be understood and minimized. The best depth resolution generally requires special conditions of analysis which may include an ultra-low primary-ion beam energy, glancing incidence angle, specimen rotation, specimen cooling to cryogenic temperature, etc., all of which cannot be easil
22、y adopted for daily SIMS analysis. In addition to this, the optimization of the analysis parameters may be quite different for each specimen. Moreover, different aspects of the depth resolution are also affected by instrumental factors such as the crater shape, ion beam homogeneity, removal of the c
23、rater edge effect, mass interference, memory effect, residual gas effect, etc. Therefore, it is not straightforward to estimate the depth resolution under given daily SIMS analysis conditions. In this International Standard, the three essential component parameters of the depth resolution, the leadi
24、ng- edge decay length, the trailing-edge decay length and the Gaussian broadening, are described and procedures are provided for the measurement of each parameter. The depth resolution parameters under daily SIMS analysis conditions can be estimated using multiple delta-layer reference materials. BS
25、ISO20341:2003blank BSISO20341:2003ANRETNIITOTS LANDNADRA ISO 43023002:1)E( ISO 3002 r llAithgs reservde 1 Surface chemical analysis Secondary-ion mass spectrometry Method for estimating depth resolution parameters with multiple delta-layer reference materials 1S c o p e 1.1 This International Standa
26、rd specifies procedures for estimating three depth resolution parameters, viz the leading-edge decay length, the trailing-edge decay length and the Gaussian broadening, in SIMS depth profiling using multiple delta-layer reference materials. 1.2 This International Standard is not applicable to delta-
27、layers where the chemical and physical state of the near-surface region, modified by the incident primary ions, is not in the steady state. 2 Normative references The following referenced documents are indispensable for the application of this document. For dated references, only the edition cited a
28、pplies. For undated references, the latest edition of the referenced document (including any amendments) applies. ISO 18115:2001, Surface chemical analysis Vocabulary 3 Symbols depth apparent peak depth leading-edge decay length trailing-edge decay length Gaussian broadening , scaling factors , scal
29、ing coefficients intensity of secondary ions as a function of depth 4 Requirements for multiple delta-layer reference materials 4.1 Ideal delta-layers have single atomic layer thickness according to the definition of a delta-layer in ISO 18115. However, it is not always possible to make delta-layers
30、 or prove the single atomic layer thickness. If ideal delta-layers are not available, the following criteria are appropriate for non-ideal delta-layers to be used as reference materials. 4.2 The matrix of sputtered surface layers shall not change during SIMS depth profiling so that no significant ch
31、anges occur in any SIMS matrix effects or in the erosion rate during depth profiling. Constant secondary-ion intensities of the matrix elements through the delta-layers are indicative of a constant matrix. z z 0 L T A L A T BC I(z) BSISO20341:2003ISO :14302(3002)E 2 ISO 3002 All rithgs reresvde 4.3
32、The surface and the delta-layers shall be flat and parallel to each other to avoid any distortion of SIMS profiles. 4.4 The thickness of the doped delta-layers shall be sufficiently less than the projected range of the primary ions so that a small variation in the thickness does not affect the profi
33、le shape. 4.5 The spacing between adjacent delta-layers shall be large enough so that the secondary-ion intensity at the valley between layers is less than of the peak intensity. 4.6 The thickness, the position and the interface roughness of the delta-layers shall be determined by high- resolution c
34、ross-sectional transmission electron microscopy, grazing incidence X-ray reflectivity, medium- energy ion-scattering spectrometry, or other appropriate methods. 5 Procedures 5.1 For adjustment and optimization of the secondary-ion mass spectrometer settings, the analysis conditions such as ion energ
35、y, ion species, ion current, secondary-ion polarity, primary-ion scan region, region analysed, the stability of the primary-ion current, specimen introduction, detected secondary ions, etc., shall be set in accordance with the manufacturers instructions or a local documented procedure. In the cases
36、when the SIMS profile shape of each delta-layer in a multiple-delta-doped reference material is not reproducible, the instrument performance shall be checked for items such as the drift of primary-ion current, the scan uniformity, etc. For good reproducibility of the estimated SIMS depth resolution
37、parameters, SIMS analysis conditions shall be adjusted so that there are more than 10 data points in the top of the intensity in a SIMS profile, and a SIMS profile shall be recorded down to an intensity below of the maximum. 5.2 For the use of this International Standard, a SIMS profile of a delta-l
38、ayer shall be described using an exponential rising edge, a Gaussian-like rounded top and an exponential trailing edge. Assuming the SIMS profile of a delta-layer to be a convolution of the two exponentials for the exponential rising edge as defined in Equation (1) and for the exponential trailing e
39、dge as defined in Equation (2), with a Gaussian distribution as defined in Equation (3), three parameters are required: the leading-edge decay length , the trailing-edge decay length , and the Gaussian broadening , usually expressed in nanometres: (1) (2) (3) 5.3 Before estimating the SIMS depth res
40、olution parameters, if the background level is higher than of the peak intensity, any constant background between each peak shall be subtracted before fitting. Using the average value of the sputtering-time intervals between any two delta peaks and the thickness of that interval, convert the sputter
41、ing time into the depth in nanometres. 1% 20 % 1% f L (z) f T (z) g(z) L T f L (z)=A L exp zz 0 L zz 0 g(z) = B 2 exp (zz 0 ) 2 2 2 1% BSISO20341:2003ISO 43023002:1)E( ISO 3002 r llAithgs reservde 3 5.4 To estimate the decay lengths and the Gaussian broadening, non-linear curve-fitting software can
42、be used with a user-defined function: (4) where (5) (6) and (7) If non-linear curve-fitting software is not available, simpler options of estimating one or two SIMS depth resolution parameters shall be used as described in Annex A. NOTE The derivation of Equation (4) may be found in reference 1 in t
43、he Bibliography and example fits of this equation to data both there and in reference 2. 6 Test report The test report shall include the following information: a) all information necessary for the identification of the specimens, the apparatus, the laboratory and the date of analysis; b) the multipl
44、e delta-layer reference material used; c) the conditions of analysis used; d) the method used to estimate the depth resolution parameters, i.e. Equation (4) or Annex A; e) the SIMS depth resolution parameters, such as the leading-edge decay length, the trailing-edge decay length and the Gaussian bro
45、adening for each delta-layer measured, and the depth of each delta-layer measured; f) any unusual features noted during the analysis; g) any operation not specified in this International Standard, as well as any optional operation which may have influenced the results. I(z)= C L + T (1+ erf 1 ) exp
46、zz 0 L + 0,5 L 2 + +( 1+ erf 2 ) exp zz 0 T + 0,5 T 2 1 = 1 2 zz 0 L 2 = 1 2 zz 0 T erf = 2 0 e y 2 dy BSISO20341:2003ISO :14302(3002)E 4 ISO 3002 All rithgs reresvde Annex A (normative) Simpler options of estimating SIMS depth resolution parameters A.1 General Simpler options for estimating one or
47、two SIMS depth resolution parameters are possible. Make a one- parameter estimation using the trailing-edge decay length. Make a two-parameter estimation with the trailing- edge decay length and the leading-edge decay length. A.2 Procedure For these simpler options, use the slope of the linear porti
48、on of a plot of the natural logarithm of the secondary- ion intensity versus depth to determine the leading-edge decay length and/or the trailing-edge decay length, which is the depth, usually expressed in nanometres, over which the secondary-ion intensity changes by a factor of e. The linear portio
49、n shall extend over at least a factor of 10 in secondary-ion intensity. Use the same procedures for adjustment and optimization of the secondary-ion mass spectrometer settings and background subtraction described in 5.1 and 5.3, respectively. For good reproducibility of the estimated SIMS depth resolution para
