1、raising standards worldwideNO COPYING WITHOUT BSI PERMISSION EXCEPT AS PERMITTED BY COPYRIGHT LAWBSI Standards PublicationSemiconductor devices Constant current electromigration testBS EN 62415:2010National forewordThis British Standard is the UK implementation of EN 62415:2010. It is identical to I
2、EC 62415:2010.The UK participation in its preparation was entrusted to Technical CommitteeEPL/47, Semiconductors.A list of organizations represented on this committee can be obtained onrequest to its secretary.This publication does not purport to include all the necessary provisions of acontract. Us
3、ers are responsible for its correct application. BSI 2010ISBN 978 0 580 61882 6ICS 31.080.01Compliance with a British Standard cannot confer immunity fromlegal obligations.This British Standard was published under the authority of the StandardsPolicy and Strategy Committee on 31 July 2010.Amendments
4、 issued since publicationAmd. No. Date Text affectedBRITISH STANDARDBS EN 62415:2010EUROPEAN STANDARD EN 62415 NORME EUROPENNE EUROPISCHE NORM June 2010 CENELEC European Committee for Electrotechnical Standardization Comit Europen de Normalisation Electrotechnique Europisches Komitee fr Elektrotechn
5、ische Normung Management Centre: Avenue Marnix 17, B - 1000 Brussels 2010 CENELEC - All rights of exploitation in any form and by any means reserved worldwide for CENELEC members. Ref. No. EN 62415:2010 E ICS 31.080 English version Semiconductor devices - Constant current electromigration test (IEC
6、62415:2010) Dispositifs semiconducteurs - Essai dlectromigration en courant constant (CEI 62415:2010) Halbleiterbauelemente - Konstantstrom-Prfverfahren zur Elektromigration (IEC 62415:2010) This European Standard was approved by CENELEC on 2010-06-01. CENELEC members are bound to comply with the CE
7、N/CENELEC Internal Regulations which stipulate the conditions for giving this European Standard the status of a national standard without any alteration. Up-to-date lists and bibliographical references concerning such national standards may be obtained on application to the Central Secretariat or to
8、 any CENELEC member. This European Standard exists in three official versions (English, French, German). A version in any other language made by translation under the responsibility of a CENELEC member into its own language and notified to the Central Secretariat has the same status as the official
9、versions. CENELEC members are the national electrotechnical committees of Austria, Belgium, Bulgaria, Croatia, Cyprus, the Czech Republic, Denmark, Estonia, Finland, France, Germany, Greece, Hungary, Iceland, Ireland, Italy, Latvia, Lithuania, Luxembourg, Malta, the Netherlands, Norway, Poland, Port
10、ugal, Romania, Slovakia, Slovenia, Spain, Sweden, Switzerland and the United Kingdom. BS EN 62415:2010EN 62415:2010 - 2 - Foreword The text of document 47/2044/FDIS, future edition 1 of IEC 62415, prepared by IEC TC 47, Semiconductor devices, was submitted to the IEC-CENELEC parallel vote and was ap
11、proved by CENELEC as EN 62415 on 2010-06-01. Attention is drawn to the possibility that some of the elements of this document may be the subject of patent rights. CEN and CENELEC shall not be held responsible for identifying any or all such patent rights. The following dates were fixed: latest date
12、by which the EN has to be implemented at national level by publication of an identical national standard or by endorsement (dop) 2011-03-01 latest date by which the national standards conflicting with the EN have to be withdrawn (dow) 2013-06-01 _ Endorsement notice The text of the International Sta
13、ndard IEC 62415:2010 was approved by CENELEC as a European Standard without any modification. _ BS EN 62415:2010 2 62415 IEC:2010 CONTENTS 1 Scope.5 2 Symbols, terms and definitions .5 2.1 Symbols 5 2.2 Terms and definitions 5 3 Background 6 4 Sample size6 5 Test structures .6 5.1 Lines .6 5.2 Via c
14、hains .7 5.3 Contact chains 7 6 Test conditions .7 7 Failure criteria 8 8 Data analysis8 Bibliography11 Figure 1 TEG of electromigration evaluation for metal line .6 Figure 2 TEG of electromigration evaluation for vias 7 Figure 3 Graph fitted lognormal distribution .8 Figure 4 Estimate procedure of
15、current density exponent.9 Figure 5 Estimation procedure of activation energy10 BS EN 62415:201062415 IEC:2010 5 SEMICONDUCTOR DEVICES CONSTANT CURRENT ELECTROMIGRATION TEST 1 Scope This standard describes a method for conventional constant current electromigration testing of metal lines, via string
16、 and contacts. 2 Symbols, terms and definitions For the purposes of this document, the following symbols, terms and definitions apply: 2.1 Symbols 2.1.1 Jvia_usethe maximum current density permitted to flow in a via of a real product 2.1.2 Jline_usethe maximum current density permitted to flow in a
17、line of a real product 2.1.3 Jvia_testthe current density in a via of a test structure during electromigration test 2.1.4 Jline_testthe current density in a line of a test structure during electromigration test 2.1.5 t(x %) time to failure of x % of the population NOTE The method for calculation of
18、t (50 %) is described in Clause 8. 2.2 Terms and definitions 2.2.1 TEG test element group. This is the test structure used for the test 2.2.2 Blech length the line length below which electromigration time to failure increases sharply 11NOTE The drift of metal atoms causes stress build-up in the meta
19、l lines, which caused a back flow of atoms. For short lines the stress gradient is higher than for long lines with the same current density. The forward flow increases more rapidly with current density than the backflow, and consequently the Blech length is inversely proportional to the current dens
20、ity. The Blech length can be determined by using a chain with different line lengths between the vias. _ 1Figures in square brackets refer to the Bibliography. BS EN 62415:2010 6 62415 IEC:2010 3 Background The background of electromigration testing as described in this procedure is based on the ass
21、umption that the entire electromigration failure time distribution stays intact when accelerated. Acceleration can be described by an activation energy and a current acceleration factor, as originally proposed by Black 2. 4 Sample size 15 samples or more are recommended for each test (each test stru
22、cture, temperature and current density). In some cases, to get a better statistical confidence of the results or to analyze a bimodal distribution, a higher number of samples might be necessary. 5 Test structures 5.1 Lines Electromigration characterization shall be carried out on fully back-end proc
23、essed samples. The metal line test structure in a 4-terminal (Kelvin) configuration shall be used (see Figure 1a).The line length is recommended to be at least 800 m. The use of monitors for opens, inter-layer shorts and optional intra-layer shorts is recommended (see Figure 1b).The line length is d
24、etermined by the constraints that short lines are not sensitive to failure and exhibit the Blech effect 1, and too long lines require high voltages. For line lengths J2 J3(A/cm2) t1,t2,t3(h): failure time when the cumulative failure reaches A1 percent. Figure 3 Graph fitted lognormal distribution BS
25、 EN 62415:201062415 IEC:2010 9 Extrapolation to other conditions is done using Blacks equation with no line width term: () ( )exp(% TkEajAxtn=(2) where A is a process-dependent factor, j is the current density, n is the current exponent, Ea is the activation energy, k is the Boltzmann constant, and
26、T is the absolute temperature. It is assumed that this formula holds for all fail percentages, in other words that the spread of the distribution is not affected by the acceleration. For the determination of the activation energy Ea, three temperatures, and for the determination of the current densi
27、ty exponent n, three current densities should be used. The power exponent “n” is determined by plotting for a fixed temperature the logarithm of t(A1 %) versus current density. The slope of this plot gives n (see Figure 4). Current density J Ln(timetofailure)tuseSlopeThe slope power exponent symbol
28、n t3t2t1J3J2J1JuseIEC 1124/10 Figure 4 Estimate procedure of current density exponent The activation energy is determined by plotting for a fixed current density the logarithm of t(A1 %) versus 1/T. The slope of this plot gives Ea (see Figure 5). Using above acceleration factors, estimate lifetime t
29、(F%) in the use condition (a certain temperature and current density). NOTE For Log normal distribution the correct time to be determined is the time at 50 % failure. It has the largest confidence. So, when the current density power exponent or temperature acceleration factor is calculated, it is pr
30、eferable to calculate using the failure rate which is near to 50 %. BS EN 62415:2010 10 62415 IEC:2010 1 000/T (1/K) Ln(to failure time) Arrhenius t1Slope Ea t2t3T1T2T3IEC 1125/10 Figure 5 Estimation procedure of activation energy When a sufficient data base is available, Ea and n can be extracted f
31、rom that data base for reasonably similar processes. Typical values for Ea and n shall be used, unless determined otherwise: Ea = 0,85 eV, n = 1,7 AlCu bamboo Ea = 0,65 eV, n = 2 AlCu polycrystalline Ea = 0,70 eV, n = 2 AlSiCu Ea = 0,55 eV, n = 2 AlSi Ea = 0,90 eV, n = 1,1 Cu BS EN 62415:201062415 I
32、EC:2010 11 Bibliography 1 ”Electromigration in Thin Aluminum films on Titanium Nitride”, I. Blech, J. Appl. Phys., 47, 1976, pp. 1203. 2 “Electromigration failure modes in aluminum metallization for semiconductor devices”, J.R.Black, Proc. IEEE 57, 1587, 1969. 3 ”Linewidth dependence of electromigra
33、tion in evaporated Al-0.5 %Cu,”, S. Vaidya, T.T. Sheng, A.K. Sinha , Applied Physics Letters, 1980,Volume 36, Issue 6, pp. 464-466. 4 “Standard Method for Measuring and Using the Temperature Coefficient of Resistance to Determine the Temperature of a Metallization Line”, EIA/JESD 33. _ BS EN 62415:2
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