1、Designation: F1467 11F1467 18Standard Guide forUse of an X-Ray Tester (10 keV Photons) in IonizingRadiation Effects Testing of Semiconductor Devices andMicrocircuits1This standard is issued under the fixed designation F1467; the number immediately following the designation indicates the year oforigi
2、nal adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. Asuperscript epsilon () indicates an editorial change since the last revision or reapproval.1. Scope1.1 This guide covers recommended procedures for the use of X-ray te
3、sters (that is, sources with a photon spectrum having 10keV mean photon energy and 50 keV maximum energy) in testing semiconductor discrete devices and integrated circuits foreffects from ionizing radiation.1.2 The X-ray tester may be appropriate for investigating the susceptibility of wafer level o
4、r delidded microelectronic devicesto ionizing radiation effects. It is not appropriate for investigating other radiation-induced effects such as single-event effects (SEE)or effects due to displacement damage.1.3 This guide focuses on radiation effects in metal oxide semiconductor (MOS) circuit elem
5、ents, either designed (as in MOStransistors) or parasitic (as in parasitic MOS elements in bipolar transistors).1.4 Information is given about appropriate comparison of ionizing radiation hardness results obtained with an X-ray tester tothose results obtained with cobalt-60 gamma irradiation. Severa
6、l differences in radiation-induced effects caused by differences inthe photon energies of the X-ray and cobalt-60 gamma sources are evaluated. Quantitative estimates of the magnitude of thesedifferences in effects, and other factors that should be considered in setting up test protocols, are present
7、ed.1.5 If a 10-keV X-ray tester is to be used for qualification testing or lot acceptance testing, it is recommended that such testsbe supported by cross checking with cobalt-60 gamma irradiations.1.6 Comparisons of ionizing radiation hardness results obtained with an X-ray tester with results obtai
8、ned with a LINAC, withprotons, etc. are outside the scope of this guide.1.7 Current understanding of the differences between the physical effects caused by X-ray and cobalt-60 gamma irradiations isused to provide an estimate of the ratio (number-of-holes-cobalt-60)/(number-of-holes-X-ray). Several c
9、ases are defined where thedifferences in the effects caused by X-rays and cobalt-60 gammas are expected to be small. Other cases where the differences couldpotentially be as great as a factor of four are described.1.8 It should be recognized that neither X-ray testers nor cobalt-60 gamma sources wil
10、l provide, in general, an accuratesimulation of a specified system radiation environment. The use of either test source will require extrapolation to the effects to beexpected from the specified radiation environment. In this guide, we discuss the differences between X-ray tester and cobalt-60gamma
11、effects. This discussion should be useful as background to the problem of extrapolation to effects expected from a differentradiation environment. However, the process of extrapolation to the expected real environment is treated elsewhere (1, 2).21.9 The time scale of an X-ray irradiation and measur
12、ement may be much different than the irradiation time in the expecteddevice application. Information on time-dependent effects is given.1.10 Possible lateral spreading of the collimated X-ray beam beyond the desired irradiated region on a wafer is also discussed.1.11 Information is given about recom
13、mended experimental methodology, dosimetry, and data interpretation.1.12 Radiation testing of semiconductor devices may produce severe degradation of the electrical parameters of irradiateddevices and should therefore be considered a destructive test.1 This guide is under the jurisdiction of ASTM Co
14、mmittee F01 on Electronicsand is the direct responsibility of Subcommittee F01.11 on Nuclear and Space RadiationEffects.Current edition approved Oct. 1, 2011March 1, 2018. Published October 2011April 2018. Originally approved in 1993. Last previous edition approved in 20052011 asF1467 - 99F1467 - 11
15、.(2005)1. DOI: 10.1520/F1467-11.10.1520/F1467-18.2 The boldface numbers in parentheses refer to the list of references at the end of this guide.This document is not an ASTM standard and is intended only to provide the user of an ASTM standard an indication of what changes have been made to the previ
16、ous version. Becauseit may not be technically possible to adequately depict all changes accurately, ASTM recommends that users consult prior editions as appropriate. In all cases only the current versionof the standard as published by ASTM is to be considered the official document.Copyright ASTM Int
17、ernational, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States11.13 The values stated in SI units are to be regarded as standard. No other units of measurement are included in this standard.1.14 This standard does not purport to address all of the safety concerns, if
18、 any, associated with its use. It is the responsibilityof the user of this standard to establish appropriate safety safety, health, and healthenvironmental practices and determine theapplicability of regulatory limitations prior to use.1.15 This international standard was developed in accordance wit
19、h internationally recognized principles on standardizationestablished in the Decision on Principles for the Development of International Standards, Guides and Recommendations issuedby the World Trade Organization Technical Barriers to Trade (TBT) Committee.2. Referenced Documents2.1 ASTM Standards:3
20、E170 Terminology Relating to Radiation Measurements and DosimetryE666 Practice for Calculating Absorbed Dose From Gamma or X RadiationE668 Practice for Application of Thermoluminescence-Dosimetry (TLD) Systems for Determining Absorbed Dose inRadiation-Hardness Testing of Electronic DevicesE1249 Prac
21、tice for Minimizing Dosimetry Errors in Radiation Hardness Testing of Silicon Electronic Devices Using Co-60SourcesE1894 Guide for Selecting Dosimetry Systems for Application in Pulsed X-Ray Sources2.2 International Commission on Radiation Units and Measurements Reports:ICRU Report 33Quantities and
22、Units for Use in Radiation Protection42.3 United States Department of Defense Standards:MIL-STD-883, Method 1019, Ionizing Radiation (Total Dose) Test Method53. Terminology3.1 Definitions:3.1.1 absorbed-dose enhancement, nincrease (or decrease) in the absorbed dose (as compared with the equilibrium
23、absorbeddose) at a point in a material of interest; this can be expected to occur near an interface with a material of higher or lower atomicnumber.3.1.2 average absorbed dose, nmass weighted mean of the absorbed dose over a region of interest.3.1.3 average absorbed-dose enhancement factor, nratio o
24、f the average absorbed dose in a region of interest to the equilibriumabsorbed dose.NOTE 1For a description of the necessary conditions for measuring equilibrium absorbed dose see the term charged particle equilibrium inTerminology E170 which provides definitions and descriptions of other applicable
25、 terms of this guide. In addition, definitions appropriate to the subjectof this guide may be found in ICRU Report 33.NOTE 2The SI unit for absorbed dose is the gray (Gy), defined as one J/kg. The commonly used unit, the rad (radiation absorbed dose), is definedin terms of the SI units by 1 rad = 0.
26、01 Gy. (For additional information on calculation of absorbed dose see Practice E666.)3.1.4 equilibrium absorbed dose, nabsorbed dose at some incremental volume within the material in which the condition ofelectron equilibrium (the energies, number, and direction of charged particles induced by the
27、radiation are constant throughout thevolume) exists (see Terminology E170).3.1.4.1 DiscussionFor practical purposes the equilibrium absorbed dose is the absorbed dose value that exists in a material at a distance in excessof a minimum distance from any interface with another material. This minimum d
28、istance being greater than the range of themaximum energy secondary electrons generated by the incident photons.3.1.5 ionizing radiation effects, nthe changes in the electrical parameters of a microelectronic device resulting fromradiation-induced trapped charge. These are also sometimes referred to
29、 as total dose effects.3.1.6 time dependent effects, nthe change in electrical parameters caused by the formation and annealing of radiation-inducedelectrical charge during and after irradiation.3 For referencedASTM standards, visit theASTM website, www.astm.org, or contactASTM Customer Service at s
30、erviceastm.org. For Annual Book of ASTM Standardsvolume information, refer to the standards Document Summary page on the ASTM website.4 Available from International Commission on Radiation Units and Measurements (ICRU), 7910 Woodmont Ave., Suite 400, Bethesda, MD 20841-3095, http:/www.icru.org.5 Ava
31、ilable from Standardization Documents Order Desk, DODSSP, Bldg. 4, Section D, 700 Robbins Ave., Philadelphia, PA 19111-5098, http:/dodssp.daps.dla.mil.F1467 1824. Significance and Use4.1 Electronic circuits used in many space, military and nuclear power systems may be exposed to various levels of io
32、nizingradiation dose. It is essential for the design and fabrication of such circuits that test methods be available that can determine thevulnerability or hardness (measure of nonvulnerability) of components to be used in such systems.4.2 Manufacturers are currently selling semiconductor parts with
33、 guaranteed hardness ratings, and the military specificationsystem is being expanded to cover hardness specification for parts. Therefore test methods and guides are required to standardizequalification testing.4.3 Use of low energy (10 keV) X-ray sources has been examined as an alternative to cobal
34、t-60 for the ionizing radiationeffects testing of microelectronic devices (3, 4, 5, 6). The goal of this guide is to provide background information and guidancefor such use where appropriate.NOTE 3Cobalt-60The most commonly used source of ionizing radiation for ionizing radiation (“total dose”) test
35、ing is cobalt-60. Gamma rays withenergies of 1.17 and 1.33 MeV are the primary ionizing radiation emitted by cobalt-60. In exposures using cobalt-60 sources, test specimens must beenclosed in a lead-aluminum container to minimize dose-enhancement effects caused by low-energy scattered radiation (unl
36、ess it has been demonstratedthat these effects are negligible). For this lead-aluminum container, a minimum of 1.5 mm of lead surrounding an inner shield of 0.7 to 1.0 mm ofaluminum is required. (See 8.2.2.2 and Practice E1249.)4.4 The X-ray tester has proven to be a useful ionizing radiation effect
37、s testing tool because:4.4.1 It offers a relatively high dose rate, in comparison to most cobalt-60 sources, thus offering reduced testing time.4.4.2 The radiation is of sufficiently low energy that it can be readily collimated. As a result, it is possible to irradiate a singledevice on a wafer.4.4.
38、3 Radiation safety issues are more easily managed with an X-ray irradiator than with a cobalt-60 source. This is due bothto the relatively low energy of the photons and due to the fact that the X-ray source can easily be turned off.4.4.4 X-ray facilities are frequently less costly than comparable co
39、balt-60 facilities.4.5 The principal radiation-induced effects discussed in this guide (energy deposition, absorbed-dose enhancement, electron-hole recombination) (see Appendix X1) will remain approximately the same when process changes are made to improve theperformance of ionizing radiation hardne
40、ss of a part that is being produced. This is the case as long as the thicknesses andcompositions of the device layers are substantially unchanged.As a result of this insensitivity to process variables, a 10-keV X-raytester is expected to be an excellent apparatus for process improvement and control.
41、4.6 Several published reports have indicated success in intercomparing X-ray and cobalt-60 gamma irradiations usingcorrections for dose enhancement and for electron-hole recombination. Other reports have indicated that the present understandingof the physical effects is not adequate to explain exper
42、imental results.As a result, it is not fully certain that the differences betweenthe effects of X-ray and cobalt-60 gamma irradiation are adequately understood at this time. (See 8.2.1 and Appendix X2.) Becauseof this possible failure of understanding of the photon energy dependence of radiation eff
43、ects, if a 10-keV X-ray tester is to be usedfor qualification testing or lot acceptance testing, it is recommended that such tests should be supported by cross checking withcobalt-60 gamma irradiations. For additional information on such comparison, see X2.2.4.4.7 Because of the limited penetration
44、of 10-keV photons, ionizing radiation effects testing must normally be performed onunpackaged devices (for example, at wafer level) or on unliddeddelidded devices.5. Interferences5.1 Absorbed-Dose EnhancementAbsorbed-dose enhancement effects (see 8.2.1 and X1.3) can significantly complicate thedeter
45、mination of the absorbed dose in the region of interest within the device under test. In the photon energy range of the X-raytester, these effects should be expected when there are regions of quite different atomic number within hundreds of nanometres ofthe region of interest in the device under tes
46、t.NOTE 4An example of a case where significant absorbed dose enhancement effects should be expected is a device with a tantalum silicidemetallization within 200 nm of the SiO2 gate oxide.5.2 Electron-Hole RecombinationOnce the absorbed dose in the sensitive region of the device under test is determi
47、ned,interpretation of the effects of this dose can be complicated by electron-hole recombination (see 8.2.1 and X1.5).5.3 Time-Dependent EffectsThe charge in device oxides and at silicon-oxide interfaces produced by irradiation may changewith time. Such changes take place both during and after irrad
48、iation. Because of this, the results of electrical measurementscorresponding to a given absorbed dose can be highly dependent upon the dose rate and upon the time during and after theirradiation at which the measurement takes place (see X1.7 for further detail).NOTE 5The dose rates used for X-ray te
49、sting are frequently much higher than those used for cobalt-60 testing. For example, cobalt-60 testing isspecified by Military Test Method 1019.4Method 1019 to be in the range of 0.5 to 3 Gy(Si)/s (50 to 300 rads/(Si)/s). For comparison, X-ray testing iscommonly carried out in the range of 2 to 30 Gy(Si)/s (200 to 3000 rads(Si)/s).5.4 HandlingAs in any other type of testing, care must be taken in handling the parts. This especially applies to parts that aresusceptible to electrostatic discharge damage.F1467 1836. Apparatus6.1 X-Ray TesterA suitable X-
