1、DRAFT FOR DEVELOPMENT DD ISO/TR 15969:2001 Surface chemical analysis Depth profiling Measurement of sputtered depth ICS 17.040.20; 71.040.40 NO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWDD ISO/TR 15969:2001 This Draft for Development, having been prepared under the direction
2、 of the Sector Policy and Strategy Committee for Materials and Chemicals, was published under the authority of the Standards Policy and Strategy Committee on 01 October 2001 BSI 01 October 2001 ISBN 0 580 38501 9 National foreword This Draft for Development reproduces verbatim ISO/TR 15969:2001. Thi
3、s publication is not to be regarded as a British Standard. It is being issued in the Draft for Development series of publications and is of a provisional nature because the source document is an ISO Technical Report which is not an international standard. It should be applied on this provisional bas
4、is, so that information and experience of its practical application may be obtained. Comments arising from the use of this Draft for Development are requested so that UK experience can be reported to the international organization responsible for its conversion into an international standard. A revi
5、ew of this publication will be initiated 2 years after its publication by the international organization so that a decision can be taken on its status at the end of its three-year life. The commencement of the review period will be notified by an announcement in Updated Standards. According to the r
6、eplies received by the end of the review period, the responsible BSI Committee will decide whether to support the conversion into an international standard. Comments should be sent in writing to the Secretary of BSI Technical Committee CII/60, Surface chemical analysis, at 389 Chiswick High Road, Lo
7、ndon W4 4AL, giving the document reference and clause number and proposing, where possible, an appropriate revision of the text. A list of organizations represented on this committee can be obtained on request to its secretary. Cross-references The British Standards which implement international or
8、European publications referred to in this document may be found in the BSI Standards Catalogue under the section entitled “International Standards Correspondence Index”, or by using the “Find” facility of the BSI Standards Electronic Catalogue. Summary of pages This document comprises a front cover,
9、 an inside front cover, the ISO/TR title page, pages ii to v, a blank page, pages 1 to 12, an inside back cover and a back cover. The BSI copyright date displayed in this document indicates when the document was last issued. Amendments issued since publication Amd. No. Date CommentsReference number
10、ISO/TR 15969:2001(E) TECHNICAL REPORT ISO/TR 15969 First edition 2001-06-01 Surface chemical analysis Depth profiling Measurement of sputtered depth Analyse chimique des surfaces Profilage dpaisseur Mesurage de lpaisseur bombarde DDISO/TR15969:2001ii DDISO/TR15969:2001IS/OTR :96951(1002)Eiii Content
11、s Page Foreword.iv 1 Scope 1 2 Terms and definitions .1 3 Abbreviated terms .2 4 Methods of determination of the sputtered depth2 4.1 Crater depth measurement after sputter profiling .2 4.2 Comparison with sputter profiled samples having interfaces as depth markers.5 4.3 Typical applications and unc
12、ertainties of the different methods.9 Annex A Survey of typical applications and uncertainties of the different methods.10 Bibliography11 DDISO/TR15969:2001IS/OTR :96951(1002)E iv Foreword ISO (the International Organization for Standardization) is a worldwide federation of national standards bodies
13、 (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 right to be represented on that committee. International organizations,
14、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. International Standards are drafted in accordance with the rules given in the ISO/
15、IEC Directives, Part 3. 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 an International Standard requires approval by at least 75 % of the me
16、mber bodies casting a vote. In exceptional circumstances, when a technical committee has collected data of a different kind from that which is normally published as an International Standard (“state of the art“, for example), it may decide by a simple majority vote of its participating members to pu
17、blish a Technical Report. A Technical Report is entirely informative in nature and does not have to be reviewed until the data it provides are considered to be no longer valid or useful. Attention is drawn to the possibility that some of the elements of this Technical Report may be the subject of pa
18、tent rights. ISO shall not be held responsible for identifying any or all such patent rights. ISO/TR 15969 was prepared by Technical Committee ISO/TC 201, Surface chemical analysis, Subcommittee SC 4, Depth profiling. DDISO/TR15969:2001IS/OTR :96951(1002)Ev Introduction This Technical Report is inte
19、nded to be used as follows: a) For the determination of the depth scale in sputter depth profiling where signal intensity is obtained as a function of sputtering time (or ion dose density). The sputtered depth per sputtering time is the sputtering rate (typically reported in nm/s). b) To enhance the
20、 comparability of depth profiling data obtained with different instruments and to increase the reliability and use of depth profiling in industrial applications. c) To serve as the basis for the development of International Standards on the measurement of sputtered depth. DDISO/TR15969:2001DDISO/TR1
21、5969:2001TECINHCAL ROPETR IS/OTR :96951(1002)E ISO 1002 All rights rsedevre 1 Surface chemical analysis Depth profiling Measurement of sputtered depth 1 Scope This Technical Report gives guidelines for measuring the sputtered depth in sputtered depth profiling. The methods of sputtered depth measure
22、ment described in this Technical Report are applicable to techniques of surface chemical analysis when used in combination with ion bombardment for the removal of a part of a solid sample to a ty pi ca lspu tte re dde p tho fu ptosev e ralmi cro me tre s. 2 Terms and definitions For the purposes of
23、this Technical Report, the following terms and definitions apply. NOTE The terms used in this Technical Report follow basically the definitions in ASTM E 673-95c 1 . These definitions are to be modified to conform to those being developed by ISO/TC 201/SC 1 on Terminology. See also 2 and 3. 2.1 sput
24、tered depth distance z (m) (perpendicular to the surface) between the original surface and the analysed sample surface after removal of a measurable amount of matter as a result of sputter profiling, which is given by m z A (1) where m is the removed sample mass (kg); A i sth espu tte reda rea(m 2 )
25、; is the density of the sample (kg/m 3 ) 2.2 crater depth average distance (perpendicular to the surface) between the original surface and the region of a crater bottom from which the measured signal is derived NOTE The crater depth is equal to the sputtered depth if primary-ion implantation and ret
26、ention, which may cause enlargement (“swelling”) of the sample in the direction perpendicular to the surface, is negligible 5 . If the sputtered depth is measured by crater depth measurement outside the analysis chamber, surface reactions (e.g. oxidation) may add to the swelling of the crater bottom
27、, i.e. the crater depth is generally measured as being less than the sputtered depth. DDISO/TR15969:20011IS/OTR :96951(1002)E 2 ISO 1002 All rights rsedevre 3 Abbreviated terms AES Auger electron spectroscopy AFM Atomic force microscopy EDS Energy dispersive spectrometry EPMA Electron probe microana
28、lysis FIB Focused ion beam GIXR Grazing incidence X-ray reflectivity MEIS Medium energy ion scattering RBS Rutherford backscattering spectrometry SAM Scanning Auger microscopy SEM Scanning electron microscopy SIMS Secondary-ion mass spectrometry TEM Transmission electron microscopy XPS X-ray photoel
29、ectron spectroscopy XRF X-ray fluorescence 4 Methods of determination of the sputtered depth 4.1 Crater depth measurement after sputter profiling 4.1.1 General description Usually, the result of sputter profiling is a signal intensity as a function of the sputtering time. The total sputtering time c
30、orresponds to the crater depth and the average sputtering rate is obtained by dividing the crater depth by the sputtering time. Crater depth measurements are usually performed by mechanical stylus profilometry 6 or, less commonly in use, by optical interferometry. Optical instruments and scanned-pro
31、be microscopes give a two- dimensional view of the crater and its non-uniformities. 4.1.2 Mechanical stylus crater depth measurement Mechanical stylus profilometers convert the deflection of a stylus in mechanical contact with the surface into a voltage that is amplified and then displayed directly
32、on a strip chart, or digitized and processed in a computer. In some instruments, the stylus is scanned across the sample containing the crater, and in others the sample is scanned under the stylus. Profilometers typically produce one-dimensional line scans, though some modern instruments and scanned
33、 probe microscopes are capable of producing two-dimensional scans by making an automated series of closely spaced one-dimensional scans. Stylus profilometry is appropriate for measuring the depths of craters in which the roughness of the original surface and that of the crater bottom are small compa
34、red to the crater depth. It is commonly used for craters made in semiconductors during SIMS depth profiling. The minimum depth that can be measured successfully depends on the acoustic and electronic noise of the profilometer as well as the surface roughness. In modern instruments the minimum depth
35、may be as small as 10 nm, and the maximum may be as great as 100 m. To perform a crater depth measurement with a one-dimensional profilometer, a scan is made through the centre of the crater and over a sufficient distance of the unsputtered top surface on either side to establish an accurate DDISO/T
36、R15969:20012IS/OTR :96951(1002)E ISO 1002 All rights rsedevre 3 baseline, as shown in Figure 1. Multiple scans are made over different traces through the crater centre to determine the repeatability of the crater depth measurement. The depth is measured on a computerized profilometer by determining
37、the average height difference between a region in the centre of the crater at A and two regions of the reference surface on opposite sides at B and C. Figure 1 shows an example of a computerized profilometer trace of a sputtered crater in single crystal silicon approximately 0,5 mi nd e p t h .T h e
38、t h r e ep a i r so f vertical cursor lines indicate the regions over which the depth is averaged. Figure 1 E xa mpleofs ty luspr ofilome trytr ac eofa0,5 m deep crater in silicon The depth scale of the stylus profilometer is calibrated with standard step-heights or grooves that are traceable to fun
39、damental length standards (wavelength of light). A typical calibration uncertainty is 1 % for a 1 m standard gauge. The uncertainty of a crater depth measurement is a combination of calibration uncertainty and profilometer noise. In a recent round-robin experiment on craters in silicon, uncertaintie
40、s ranged from 1,3 % for a 2 mc r a t e r to 4,7 % for a 0,1 mc r a t e r 6 . NOTE For the purposes of this Technical Report, typical uncertainties are given as one-standard-deviation uncertainties. Advantages of stylus profilometry for crater depth measurements are that it is rapid, requires no samp
41、le preparation, and reveals the size, shape, and flatness of the crater bottom which are measures of the ion beam current density. A disadvantage is that corrections may be necessary to convert crater depth to sputtered depth in the case of non-negligible swelling or oxidation. In the case of layere
42、d structures with different sputtering rates, separate craters must be made for each interface so that the individual sputtering rates can be determined. Otherwise only an average sputtering rate is obtained. 4.1.3 Optical interferometry crater depth measurement Optical interferometry is a simple an
43、d convenient non-contact method of crater depth measurement for which the equipment is relatively cheap to buy and easy to use. This method utilizes a metallurgical microscope equipped with an interference attachment (Mireau or Michelson objective, sample tilting stage and monochromatic light source
44、/interference filter) and is only applicable to smooth flat samples, for example flat glass, coatings on glass and semiconductor wafers. Generally, metal samples are too rough for this method to be suitable. The crater to be measured is placed on the microscope sample stage, which usually is capable
45、 of producing a controlled tilting movement of the sample as well as the usual x-y translation. Using the interference objective or a normal objective, the crater of interest is located and placed at the centre of the field of view. This operation can be done with white light illumination. If a norm
46、al objective has been used, the interference objective is then put in place DDISO/TR15969:20013IS/OTR :96951(1002)E 4 ISO 1002 All rights rsedevre and the sample height adjusted to give white light interference fringes across the crater. The interference filter is put in place and the sample illumin
47、ated with monochromatic light. Using the tilting adjustment of the sample stage, the sample is tilted to spread the fringes to a suitable separation and/or to rotate them so that they produce a suitable contour map of the crater. Take care to ensure that there are no other craters on the sample near
48、 to the crater of interest that cause displacements of the fringes on either side of the crater that are to be used for the measurement. Produce a hard copy of the image. Figure 2 shows an example: Using a straight-edged ruler draw two lines (A and B) through the centres of two adjacent fringes and
49、measure the separation between them. Preferably one of these lines (A) should cross the crater. Draw a third line through the centre of a fringe running through the centre of the crater (C). Count the number of fringes intersected by the line (A) crossing the crater and estimate the fraction of a fringe spacing between that line and the line through the fringe in the crater (C). In the case of Figure 2, this fraction will be equal to the ratio of separation of lines B and C to that of A and B. Mult
