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1、 Reference number ISO 18516:2006(E) ISO 2006 INTERNATIONAL STANDARD ISO 18516 First edition 2006-11-01 Surface chemical analysis Auger electron spectroscopy and X-ray photoelectron spectroscopy Determination of lateral resolution Analyse chimique des surfaces Spectroscopie dlectrons Auger et spectro
2、scopie de photolectrons de rayons X Dtermination de la rsolution latrale Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:04:53 MDTNo reproduction or networking permitted witho
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6、cretariat at the address given below. ISO 2006 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 either ISO at the
7、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 2006 All rights reserved Copyright International Organization
8、 for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 18516:2006(E) ISO 2006 All rights reserved iii Contents Page Foreword iv Introd
9、uction v 1 Scope . 1 2 Normative references. 1 3 Terms, definitions, symbols and abbreviated terms. 1 3.1 Terms and definitions. 1 3.2 Symbols and abbreviated terms . 2 4 General information 2 4.1 Background information 2 4.2 Measurement of lateral resolution in AES and XPS 3 4.3 Dependence of later
10、al resolution on scan direction. 3 4.4 Methods for the measurement of lateral resolution in AES and XPS . 4 5 Measurement of lateral resolution with the straight-edge method . 4 5.1 Introduction. 4 5.2 Variants of the straight-edge method. 4 5.3 Selection of the straight-edge specimen 5 5.4 Mounting
11、 the straight-edge specimen 5 5.5 Cleaning the straight-edge specimen. 5 5.6 Operating the instrument. 6 5.7 Data collection 6 5.8 Data analysis. 8 6 Measurement of lateral resolution with the grid method 10 6.1 Introduction. 10 6.2 Selection of the grid specimen 10 6.3 Mounting the grid specimen 10
12、 6.4 Cleaning the grid specimen. 10 6.5 Operating the instrument. 11 6.6 Data collection 11 6.7 Data analysis. 13 7 Measurement of lateral resolution with the gold-island method. 13 7.1 Introduction. 13 7.2 Selection of the gold-island specimen. 13 7.3 Mounting the gold-island specimen . 13 7.4 Clea
13、ning the gold-island specimen 14 7.5 Operating the instrument. 14 7.6 Data collection 14 7.7 Data analysis. 16 Annex A (informative) Determination of lateral resolution of an XPS instrument with a focused X-ray spot 17 Annex B (informative) Determination of lateral resolution from a secondary-electr
14、on line scan . 19 Annex C (informative) Determination of lateral resolution from Auger-electron line scans 21 Bibliography. 24 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:
15、04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 18516:2006(E) iv ISO 2006 All rights reserved Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies (ISO member bodies). The work of preparing Intern
16、ational 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 right to be represented on that committee. International organizations, governmental and non-governmental, in liaison with
17、 ISO, also take part in the work. ISO collaborates closely with the International Electrotechnical 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
18、 committees is to prepare International Standards. Draft International Standards adopted by the 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
19、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 18516 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee SC 5, Auger electron spec
20、troscopy. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 18516:2006(E) ISO 2006 All rights
21、 reserved v Introduction Auger electron spectroscopy (AES) and X-ray photoelectron spectroscopy (XPS) are surface-analytical techniques that are used to generate chemical maps and line scans of surfaces, and to provide spectroscopic analyses from defined areas. These techniques can have lateral reso
22、lutions as good as 10 nm for AES and can cover areas as large as many square centimetres in XPS. Different instruments generate images or define spectroscopic areas with different lateral resolutions, so inter-comparisons of image quality are poorly defined without clearly defined methods and terms
23、with which to express the results. Different settings of an instrument may also change the lateral resolution. An analyst needs to have a suitable method to measure the lateral resolution of an instrument for any given settings. In this way, analysts can obtain the optimum lateral resolution from a
24、given instrument, appropriate to the analytical requirements, in a consistent and clear way. The resolution actually achieved in subsequent analyses will approach these values in XPS but, generally, the resolution in AES may be degraded by the effects of electron backscattering. The ability of the a
25、nalyst to realise these resolutions in an effective way will, of course, also depend on the quality of the signal levels obtained. This International Standard describes three methods for the determination of lateral resolution in AES and XPS. The method chosen for use depends on the expected value o
26、f the lateral resolution. Annexes A, B and C provide illustrative examples of the measurement of lateral resolution. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:04:53 MDTN
27、o reproduction or networking permitted without license from IHS -,-,- Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:04:53 MDTNo reproduction or networking permitted without
28、license from IHS -,-,- INTERNATIONAL STANDARD ISO 18516:2006(E) ISO 2006 All rights reserved PROOF/PREUVE 1 Surface chemical analysis Auger electron spectroscopy and X-ray photoelectron spectroscopy Determination of lateral resolution 1 Scope This International Standard describes three methods for m
29、easuring the lateral resolution achievable in Auger electron spectrometers and X-ray photoelectron spectrometers under defined settings. The straight-edge method is suitable for instruments where the lateral resolution is expected to be larger than 1 m. The grid method is suitable if the lateral res
30、olution is expected to be less than 1 m but more than 20 nm. The gold- island method is suitable for instruments where the lateral resolution is expected to be smaller than 50 nm. Annexes A, B and C provide illustrative examples of the measurement of lateral resolution. 2 Normative references The fo
31、llowing 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. ISO 18115:2001, Surface chemical analysis Vocabulary 3
32、Terms, definitions, symbols and abbreviated terms 3.1 Terms and definitions For the purposes of this document, the terms and definitions given in ISO 18115 apply. The definition of lateral resolution is repeated here for convenience. 3.1.1 resolution, lateral distance measured either in the plane of
33、 the sample surface or in a plane at right angles to the axis of the image-forming optics over which changes in composition can be separately established with confidence NOTE 1 The choice of plane should be stated. NOTE 2 In practice, the lateral resolution may be realized as either (i) the FWHM of
34、the intensity distribution from a very small emitting point on the sample, or (ii) the distance between the 12 % and 88 % intensity points in a line scan across a part of the sample containing a well-defined step function for the signal relating to the property being resolved. These two values are e
35、quivalent for a Gaussian intensity distribution. For other distributions, other parameters may be more appropriately chosen. Often, for a step function, the distance between the 20 % and 80 % intensity points or the 16 % and 84 % intensity points in the line scan are used. The latter pair gives the
36、two-sigma width for a Gaussian resolution function. ISO 18115:2001, definition 5.255 NOTE 3 For the purposes of this International Standard, measurement in the plane of the sample is preferred. Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=N
37、ASA Technical Standards 1/9972545001 Not for Resale, 04/12/2007 22:04:53 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO 18516:2006(E) 2 ISO 2006 All rights reserved 3.2 Symbols and abbreviated terms AES Auger electron spectroscopy d diameter of an electron beam (of axi
38、al symmetry) incident on a sample surface FWHM full width at half maximum XPS X-ray photoelectron spectroscopy x parameter needed for the determination of lateral resolution; the measurement of lateral resolution begins when the signal intensity is x % of the maximum intensity and ends when the inte
39、nsity is (100 x) % of the maximum. In the case of r(50), x is 25 angle of incidence of an electron beam or an X-ray beam on a sample surface measured with respect to the surface normal 4 General information 4.1 Background information A common need in AES and XPS is the measurement of composition as
40、a function of position on the sample surface. Typically, an analyst wishes to determine the local surface composition of some identified region of interest. This region of interest could be a feature on a semiconductor wafer (such as an unwanted defect particle or contamination stain), a corrosion p
41、it, a fibre or an exposed surface of a composite material. With growing industrial fabrication of devices with dimensions on the micrometre and nanometre scales, particularly in the semiconductor industry and for emerging nanotechnology applications, there is an increasing need to characterize mater
42、ials using tools with lateral resolutions that are smaller than those of the features of interest. It is generally necessary in these applications to be able to determine that devices have been fabricated as intended (quality control), to evaluate new or current fabrication methods (process developm
43、ent and process control), and to identify failure mechanisms (failure analysis) of a device during its service life or after exposure to different ambient conditions. The lateral resolution is an important parameter in the application of characterization techniques such as AES and XPS for the surfac
44、e characterization of materials containing features with micrometre and nanometre dimensions. It is clearly desirable that the lateral resolution of the technique be smaller than the lateral dimensions of the feature of interest in order that the feature can be readily imaged. The feature of interes
45、t in an AES instrument might typically be initially detected in a scanning electron micrograph. The primary electron beam could then be positioned on the feature and an Auger spectrum recorded. In XPS instruments, the feature of interest must generally be detected from an image or a line scan in whi
46、ch a particular signal (often the intensity of a selected photoelectron peak) is displayed as a function of position on the sample surface. In practice, the detectability of a feature in AES and XPS measurements depends not only on the lateral resolution but also the difference in signal intensities
47、 for measurements made on and off the possible feature (materials contrast) and the observation time (through the statistical variations in the signal intensities). The detectability of a feature thus depends on an instrumental characteristic (the lateral resolution), the particular constituents of
48、the sample, and the measurement time. Reliable detection of a feature will also depend on instrumental stability (particularly the stability of the incident electron beam current in AES, the X-ray flux in XPS, and the positional stability of the sample stage with respect to the electron or X-ray beam) and the chemical stability of the sample during the time needed for acquisition of AES or XPS data. Many authors have described and discussed the lateral resolution (often referred to as spatial resolution) of AES and XPS inst