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1、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 Reference number ISOTTR 15969:ZOOl (E) 0 IS0 2001 Copyright International Organizat
2、ion for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or networking permitted without license from IHS -,-,- 1 ISO/TR 15969:2001 (E) PDF disclaimer This PDF file may contain embedded typefa
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7、e 56 CH-121 1 Geneva 20 Tel. + 41 22 749 O1 11 Fax +41227490947 E-mail copyrightQiso.ch Web www.iso.ch Printed in Switzerland 0 IS0 2001 - All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/997254500
8、1 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/TR 15969:2001(E) Contents Page Foreword . iv 1 Scope 1 2 Terms and definitions . 1 3 Abbreviated terms . 2 4 4.1 4.2 Comparison with sputter profiled samples having interfaces as depth
9、 markers . 5 4.3 Typical applications and uncertainties of the different methods . 9 Annex A Survey of typical applications and uncertainties of the different methods . 10 Bibliography 11 Methods of determination of the sputtered depth 2 Crater depth measurement after sputter profiling . 2 O IS0 200
10、1 -All rights reserved iii Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or networking permitted without license from IHS -,-,- ISOTTR 15969:2001 (E
11、) Foreword IS0 (the International Organization for Standardization) is a worldwide federation of national standards bodies (IS0 member bodies). The work of preparing International Standards is normally carried out through IS0 technical committees. Each member body interested in a subject for which a
12、 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. IS0 collaborates closely with the International Electrotechnical Commission (IEC) on all matte
13、rs of electrotechnical standardization. International Standards are drafted in accordance with the rules given in the ISO/IEC Directives, Part 3. The main task of technical committees is to prepare International Standards. Draft International Standards adopted by the technical committees are circula
14、ted to the member bodies for voting. Publication as an International Standard requires approval by at least 75 YO of the member 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 Internati
15、onal Standard (“state of the art“, for example), it may decide by a simple majority vote of its participating members to publish 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 o
16、r useful. Attention is drawn to the possibility that some of the elements of this Technical Report may be the subject of patent rights. IS0 shall not be held responsible for identifying any or all such patent rights. ISOTTR 15969 was prepared by Technical Committee ISOTTC 201, Surface chemical analy
17、sis, Subcommittee SC 4, Depth profiling. iv O IS0 2001 -All rights reserved Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or networking permitted wi
18、thout license from IHS -,-,- ISO/TR 15969:2001 (E) Introduction This Technical Report is intended 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 dep
19、th per sputtering time is the sputtering rate (typically reported in nm/s). b) To enhance the 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
20、of International Standards on the-measurement of sputtered depth. O IS0 2001 -All rights reserved V Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or
21、 networking permitted without license from IHS -,-,- TECHNICAL REPORT ISO/TR 15969:2001 (E) 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 sputt
22、ered depth measurement 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 typical sputtered depth of up to several micrometres. 2 Terms and definitions For the pur
23、poses of this Technical Report, the following terms and definitions apply. NOTE to be modified to conform to those being developed by ISOlC 201/SC 1 on Terminology. See also 2 and 3. The terms used in this Technical Report follow basically the definitions in ASTM E 673-95c Ill. These definitions are
24、 2.1 sputtered 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 where m is the removed sample mass (kg); A is the sputtered area (m2); p
25、is the density of the sample (kg/m3) 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 retenti
26、on, which may cause enlargement (“swelling”) of the sample in the direction perpendicular to the surface, is negligible 151. 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, i
27、.e. the crater depth is generally measured as being less than the sputtered depth. 0 IS0 2001 -ALI rights reserved 1 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTN
28、o reproduction or networking permitted without license from IHS -,-,- ISO/TR 15969:2001 (E) 3 Abbreviated terms AES AFM EDS EPMA FIB GIXR MEIS RBS SAM SEM SIMS TEM XPS XRF Auger electron spectroscopy Atomic force microscopy E ne rg y dispers ive spectrometry Electron probe microanalysis Focused ion
29、beam Grazing incidence X-ray reflectivity Medium energy ion scattering Rutherford backscattering spectrometry Scanning Auger microscopy Scanning electron microscopy Secondary-ion mass spectrometry Transmission electron microscopy X-ray photoelectron spectroscopy X-ray fluorescence 4 Methods of deter
30、mination 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 corresponds to the crater depth and the average sputtering rat
31、e is obtained by dividing the crater depth by the sputtering time. Crater depth measurements are usually performed by mechanical stylus profilometryl61 or, less commonly in use, by optical interferometry. Optical instruments and scanned-probe microscopes give a two- dimensional view of the crater an
32、d 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 on a strip chart, or digitized and processed in a computer.
33、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 probe microscopes are capable of producing two-dimensional
34、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 compared to the crater depth. It is commonly used for craters mad
35、e 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 may be as small as 10 nm, and the maximum may be as great as
36、 100 pm. 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 2 O IS0 2001 -All rights reserved Copyright International Organiza
37、tion for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or networking permitted without license from IHS -,-,- ISORR 15969:2001 (E) baseline, as shown in Figure i. Multiple scans are made ov
38、er 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 the average height difference between a region in the centre of the crater at A and two regions of the reference surface o
39、n 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 pm in depth. The three pairs of vertical cursor lines indicate the regions over which the depth is averaged. O 250 500 750 Length (pm) Figure
40、1 - Example of stylus profilometry trace of a 0,5 pm deep crater in silicon The depth scale of the stylus profilometer is calibrated with standard step-heights or grooves that are traceable to fundamental length standards (wavelength of light). A typical calibration uncertainty is 1 % for a i pm sta
41、ndard 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, uncertainties ranged from f 1,3 % for a 2 pm crater to f 4,7 % for a O, i pm crater A. NOTE For the purposes of thi
42、s 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 sample preparation, and reveals the size, shape, and flatness of the crater bottom which are measures of the
43、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 layered structures with different sputtering rates, separate craters must be made for each interface so that th
44、e 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 and convenient non-contact method of crater depth measurement for which the equipment is relatively cheap t
45、o 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/interference filter) and is only applicable to smooth flat samples, for example flat glass, coatings on
46、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 of producing a controlled tilting movement of the sample as welt as the usual x-y translation. Using the
47、 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 normal objective has been used, the interference objective is then put in place O IS0 2001 -All rights reserv
48、ed 3 Copyright International Organization for Standardization Provided by IHS under license with ISO Licensee=NASA Technical Standards 1/9972545001 Not for Resale, 04/20/2007 04:55:43 MDTNo reproduction or networking permitted without license from IHS -,-,- ISO/TR 15969:2001 (E) and the sample height adjusted to give white light interference fringes across the crater. The interference filter is put in place and the sample illuminated with monochromatic light. Using the tilting adjustment of the sample stage, the sample is tilted t