1、Designation: E 1438 06Standard Guide forMeasuring Widths of Interfaces in Sputter Depth ProfilingUsing SIMS1This standard is issued under the fixed designation E 1438; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of las
2、t revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide provides the SIMS analyst with a method fordetermining the width of interfaces from SIMS sputtering dataobtai
3、ned from analyses of layered specimens. This guide doesnot apply to data obtained from analyses of specimens withthin markers or specimens without interfaces such as ion-implanted specimens.1.2 This guide does not describe methods for the optimiza-tion of interface width or the optimization of depth
4、 resolution.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-bility of regulatory limitations prior to use.2.
5、Referenced Documents2.1 ASTM Standards:2E 673 Terminology Relating to Surface Analysis3. Terminology3.1 Definitions:3.1.1 See Terminology E 673 for definitions of terms used inSIMS.4. Summary of Guide4.1 This guide will allow interface widths to be calculatedfrom plots of SIMS secondary ion intensit
6、y versus time that areacquired during sputtering of layered specimens. It assumesthat a primary ion beam with a stable current density is beingused. Briefly, these plots are obtained in the following fashion:an ion beam of a particular ion species, ion energy, and angleof incidence is used to bombar
7、d a sample. The beam is rasteredor defocused so as to attempt to produce uniform currentdensity in the analyzed area, that is defined by means ofmechanical or electronic gating. The intensity of one or moresecondary ions is monitored with respect to time as sputteringcontinues.4.2 The interface widt
8、h is then determined from the second-ary ion intensity versus time data according to an arithmeticmodel described in the Procedure section. A measurement ofthe thickness of the layer overlying the interface is required.This measurement may be performed by another analyticaltechnique.5. Significance
9、and Use5.1 Although it would be desirable to measure the extent ofprofile distortion in any unknown sample by using a standardsample and this guide, measurements of interface width (pro-file distortion) can be unique to every sample composition (1,2, 3).3This guide, that describes a method that dete
10、rmines theunique width of a particular interface for the chosen set ofoperating conditions. It is primarily intended to provide amethod for checking on proper or consistent, or both, instru-ment performance. Periodic analysis of the same samplefollowed by a measurement of the interface width, in acc
11、or-dance with this guide, will provide these checks.5.2 The procedure described in this guide is adaptable toany layered sample with an interface between layers in whicha nominated element is present in one layer and absent from theother. It has been shown that for SIMS in particular (4, 5) andfor s
12、urface analysis in general (6, 7), only rigorous calibrationmethods can determine accurate interface widths. Such proce-dures are prohibitively time-consuming. Therefore the inter-face width measurement obtained using the procedure de-scribed in this guide may contain significant systematic error(8)
13、. Therefore, this measure of interface width may have norelation to similar measures made with other methods. How-ever, this does not diminish its use as a check on proper orconsistent instrument performance, or both.1This guide is under the jurisdiction of ASTM Committee E42 on SurfaceAnalysis and
14、is the direct responsibility of Subcommittee E42.06 on SIMS.Current edition approved Nov. 1, 2006. Published November 2006. Originallyapproved in 1991. Last previous edition approved in 2001 as E 1438 91 (2001).2For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Cust
15、omer Service at serviceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.3The boldface numbers given in parentheses refer to a list of references at theend of this guide.1Copyright ASTM International, 100 Barr Harbor Drive,
16、 PO Box C700, West Conshohocken, PA 19428-2959, United States.6. Apparatus6.1 The procedure described in this guide can be used todetermine an interface width from data obtained with virtuallyany SIMS instrument.6.2 Use of the interface width measurement from a layeredspecimen as a check on proper o
17、r consistent instrumentperformance, or both, does not assume that the sample ofinterest contains no interface roughness. Rather, it assumes thatthe interface roughness is consistent from one analyzed area tothe next. Any layered sample that meets this criterion issuitable for the use intended by thi
18、s guide.7. Procedure7.1 This procedure for measurement of depth resolution isbased on the amount of time required for the signal of one ofthe major elements of the layer overlying the interface to bereduced from 84 to 16 % of its average intensity in theoverlying layer. The ratio of this interface s
19、puttering time tothat of the sputtering time of the overlayer is equated to theratio of their respective thicknesses in order to obtain themeasurement of interface thickness. This is expressed in theform of the following equation (refer to Fig. 1):Dz 5 Dt/t!z (1)where:Dz = interface width,Dt = sputt
20、ering time for decrease from 84 to 16 % of thesignal intensity,t = time required to sputter through overlayer, from t =0until t is equal to the time at which the major elementreaches 50 % of its value in the overlayer, andz = thickness of overlayer.7.1.1 The measurement of sputter time (t) for the i
21、nterfacialregion and for the overlying layer thickness should be acquiredgraphically from the plot of secondary ion signal versus time.7.1.2 The thickness of the overlayer (z) is commonlyobtained from a post-profile crater measurement and assuminga constant sputter rate. The thicknesses of layers in
22、 a multilay-ered profile are only approximated by this procedure. A moreaccurate thickness value for the overlayer is obtained byhalting the sputtering at the interface, and obtaining a cratermeasurement. Alternatively, other techniques may be used tomeasure the overlying layer. Some possible techni
23、ques thatmay be used include optical interferometry, ellipsometry,selective chemical etching followed by profilometry, andspectroscopic methods such as Rutherford BackscatteringSpectrometry (RBS), X-ray Fluorescence (XRF), and AngleResolved X-ray Photoelectron Spectroscopy (ARXPS).REFERENCES(1) Witt
24、maack, K., “Vacuum,” Journal of Vacuum Science Technology,Vol 34, 1984, p. 119.(2) Wittmaack, K., Journal of Vacuum Science Technology, Vol A3, 1985,p. 1350.(3) Boudewijn, P. R., Leys, M. R., and Roozeboom, F., Surface InterfaceAnalysis, Vol 9, 1986, p. 303.(4) Galuska, A. A., “SIMS V, Proceedings o
25、f the Fifth InternationalConference,” Springer Verlag: New York, 1986, p. 363.(5) Galuska, A. A., Analytical Chemistry, Vol 55, 1984, p. 74.(6) Kirchhoff, W. H., Chambers, G. P., and Fine, J., Journal of VacuumScience Technology, Vol A4, 1986, p. 1666.(7) Fine, J., et al., Journal of Vacuum Science
26、Technology, Vol A3, 1985,p. 1413.(8) Hofmann, S., and Sanz, J. M., “Thin Film and Depth ProfileAnalysis,”H. Oechsner, ed., Springer-Verlag: New York, 1984, pp. 141158.ASTM International takes no position respecting the validity of any patent rights asserted in connection with any item mentionedin th
27、is standard. Users of this standard are expressly advised that determination of the validity of any such patent rights, and the riskof infringement of such rights, are entirely their own responsibility.This standard is subject to revision at any time by the responsible technical committee and must b
28、e reviewed every five years andif not revised, either reapproved or withdrawn. Your comments are invited either for revision of this standard or for additional standardsand should be addressed to ASTM International Headquarters. Your comments will receive careful consideration at a meeting of theres
29、ponsible technical committee, which you may attend. If you feel that your comments have not received a fair hearing you shouldmake your views known to the ASTM Committee on Standards, at the address shown below.This standard is copyrighted by ASTM International, 100 Barr Harbor Drive, PO Box C700, W
30、est Conshohocken, PA 19428-2959,United States. Individual reprints (single or multiple copies) of this standard may be obtained by contacting ASTM at the aboveaddress or at 610-832-9585 (phone), 610-832-9555 (fax), or serviceastm.org (e-mail); or through the ASTM website(www.astm.org).FIG. 1 Measurement of Interface Width, Dz,fromaPlotofSIMS Intensity Versus Ion Bombardment TimeE1438062
