1、Designation: F 615M 95 (Reapproved 2002)METRICStandard Practice forDetermining Safe Current Pulse-Operating Regions forMetallization on Semiconductor Components Metric1This standard is issued under the fixed designation F 615M; the number immediately following the designation indicates the year ofor
2、iginal adoption or, in the case of revision, the year of last 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 practice covers procedures for determining operat-ing r
3、egions that are safe from metallization burnout induced bycurrent pulses of less than 1-s duration.NOTE 1In this practice, “metallization” refers to metallic layers onsemiconductor components such as interconnect patterns on integratedcircuits. The principles of the practice may, however, be extende
4、d tonearly any current-carrying path. The term “burnout” refers to eitherfusing or vaporization.1.2 This practice is based on the application of unipolarrectangular current test pulses. An extrapolation technique isspecified for mapping safe operating regions in the pulse-amplitude versus pulse-dura
5、tion plane. A procedure is providedin Appendix X2 to relate safe operating regions establishedfrom rectangular pulse data to safe operating regions forarbitrary pulse shapes.1.3 This practice is not intended to apply to metallizationdamage mechanisms other than fusing or vaporization inducedby curre
6、nt pulses and, in particular, is not intended to apply tolong-term mechanisms, such as metal migration.1.4 This practice is not intended to determine the nature ofany defect causing failure.1.5 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It i
7、s 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. Terminology2.1 Definitions of Terms Specific to This Standard:2.1.1 failurea change in the measured resistance of610 % DR/
8、R or as agreed upon by the parties to the test.3. Summary of Practice3.1 Specimens are selected from the population being evalu-ated.3.2 The d-c resistance of each specimen is measured.3.3 Each specimen is subjected to stress from rectangularcurrent pulses varying in amplitude and duration according
9、 toa predetermined schedule of pulse width and amplitudes.3.4 A second d-c resistance measurement is made on eachspecimen after each pulse, and it is characterized as havingfailed or survived.3.5 The number, x, of specimens surviving and the totalnumber, n, of specimens tested at each pulse width an
10、damplitude are analyzed statistically to determine the burnoutlevel at each test pulse width for the desired burnout survivalprobability and confidence level.3.6 A point corresponding to the burnout level (at thedesired probability and confidence level) is plotted for each ofthe test pulse duration
11、values in the pulse-amplitude, pulse-duration plane. Based on these points, an extrapolation tech-nique is used to plot the boundary of the safe operating region.3.7 The following items are not specified by the practice andare subject to agreement by the parties to the test:3.7.1 The procedure by wh
12、ich the specimens are to beselected.3.7.2 Test patterns that will be representative of adjacentmetallization on a die or wafer (5.3).3.7.3 The schedule of pulse amplitudes and durations to beapplied to the test samples (9.8).3.7.4 The level of probability and confidence to be used incalculations to
13、establish the boundary of the safe operatingregion (10.1).3.7.5 The amount of change of resistance that will define thecriterion for failure.3.7.6 The statistical model to be used to determine theburnout probability at a desired stress level.3.7.7 The form and content of the report.1This practice is
14、 under the jurisdiction of ASTM Committee F01 on Electronicsand is the direct responsibility of Subcommittee F01.11 on Quality and HardnessAssurance.Current edition approved May 15, 1995. Published July 1995.1Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 194
15、28-2959, United States.4. Significance and Use4.1 Solid-state electronic devices subjected to stresses fromexcessive current pulses sometimes fail because a portion ofthe metallization fuses or vaporizes (suffers burnout). Burnoutsusceptibility can vary significantly from component to com-ponent on
16、a given wafer, regardless of design. This practiceprovides a procedure for establishing the limits of pulse currentoverstress within which the metallization of a given deviceshould survive.4.2 This practice can be used as a destructive test in alot-sampling program to determine the boundaries of the
17、 safeoperating region having desired survival probabilities andstatistical confidence levels when appropriate sample quantitiesand statistical analyses are used.NOTE 2The practice may be extended to infer the survivability ofuntested metallization adjacent to the specimen metallization on asemicondu
18、ctor die or wafer if care is taken that appropriate similaritiesexist in the design and fabrication variables.5. Interferences5.1 The level at which failure of metallization subjected topulsed-current overstress occurs may be dependent on thetemperature experienced by the semiconductor device. Ifsig
19、nificant differences in ambient temperature or heat sinking,or both, exist between one test situation and another, the resultsmay not be representative.NOTE 3See Appendix X1 for a discussion of factors related tometallization heat sinking.5.2 If probes are used to contact the metallization specimen,
20、suitable precautions must be taken or the results may bemisleading. The probes must not be allowed to come intocontact with the area of metallization being characterized.5.2.1 The use of Kelvin probe connections to make theresistance measurements is usually required to prevent contactresistance (at
21、the current injection point) from interfering withthe measurement.5.2.2 Probe contacts with excessive contact resistance maycause damage at the point of contact. Such damage caninterfere with the measurement.5.3 If the test is used to infer the survivability of metalliza-tion on a wafer or die, the
22、results could be misleading unlesssuch factors as the following are identical: (1) metallizationdesign geometry, (2) oxide step geometry, and (3) orientationof the metallization paths and oxide steps to the metallizationsource during deposition.NOTE 4The design and fabrication factors listed in 5.3
23、have beenshown to be important for systems of aluminum metallization depositedon SiO2/Si substrates. They are given as examples and are not intended tobe all inclusive or necessarily to apply to all metallization systems towhich this practice may be applied.NOTE 5Variations in oxide step geometry mu
24、st be expected (seeX1.4.2).5.4 A step-stress pulsing schedule is not recommended. Ifsuch a schedule is used so that each specimen is subjected tosuccessive pulses of increasing amplitude until failure occurs,the results could be misleading. It is possible that a pulse of theproper level can cause me
25、lting at a defect site without causingan open circuit; the molten metal may become redistributed sothat the defect appears cured and will lead to failure onsuccessive pulses.6. Apparatus6.1 Current-Pulse GeneratorA source of rectangular cur-rent pulses capable of meeting the following requirements:6
26、.1.1 Risetime and falltime less than 10 % of the pulsewidth(full width at half maximum amplitude (FWHM),6.1.2 Impedance high enough with respect to the specimenmetallization so that the pulse amplitude remains constant towithin 65 % between the end of the rise and beginning of thefall,6.1.3 Jitter i
27、n the pulse amplitude and width less than6 5%,6.1.4 Current amplitude and pulsewidth capability to pro-vide pulses as agreed upon by the parties to the test, and6.1.5 Single-pulse capability.NOTE 6Refer to Appendix X2 for information relating a rectangularpulse to an arbitrary pulse structure.6.2 Pu
28、lse-Monitoring Equipment, as follows:6.2.1 Voltage-Monitoring Kelvin Probe, for use in the circuitof Fig. 1, with risetime less than or equal to 5 % of thepulsewidth of the shortest pulse to be applied, and shuntcapacitance sufficiently low so that the pulse shape is notdistorted more than specified
29、 in 6.1:6.2.2 Voltage-Monitoring Resistor (R, Fig. 1), with suffi-ciently low inductance, resistance, and shunt capacitance sothat the generated pulse is not distorted more than specified in6.1 and the value of the resistance is known within 61%.6.2.3 Current Probe, for use in the circuit of Fig. 2,
30、 withrisetime less than or equal to 5 % of the pulsewidth of theshortest pulse to be applied, with an ampere-second productsufficient to ensure nonsaturation for the amplitudes anddurations of the pulses to be used and accurate within 65%.6.3 Pulse-Recording Equipment, transient digitizer, oscillo-s
31、cope with camera, storage oscilloscope, or other pulse record-ing means having a risetime less than 5 % of the width of theshortest test pulse used and capable of recording individual testpulses.6.4 Test Fixture, providing means for the current pulse to betransmitted through the metallization specim
32、en as well asthrough an equivalent resistance (see 9.5) without distortion ofthe pulse shape beyond that specified in 6.1. The test fixturemust also provide a means for connecting the metallizationspecimen to the resistance-measuring equipment (see 6.5). Thetest fixture will contact the specimen thr
33、ough either standardcomponent package leads or wafer probes. More than one testfixture may be used.FIG. 1 Pulsing Circuit Using Resistor Voltage Drop to MonitorCurrent Through SpecimenF 615M 95 (2002)26.5 Resistance-Measuring EquipmentA curve tracer,ohmmeter, or other means to be used for evaluating
34、 the d-cresistance and continuity of the current path on the specimen.The current through the specimen during this measurementshould be minimized (less than 10 % of the d-c current ratingof the specimen).6.6 Miscellaneous Circuit Components, to be used as re-quired in each of the test circuits (see
35、Fig. 1 or Fig. 2). Theswitches, leads, and connections shall be of a quality usedcustomarily in electronic circuit testing.6.7 Resistors, as required, to match the d-c resistance of theunstressed specimen to within 65%.7. Sampling7.1 The procedure by which the sample is to be taken andthe number of
36、specimens for each test condition are notspecified by this practice and are to be agreed upon by theparties to the test.8. Test Specimen8.1 The specimen may be an integrated circuit or a specialtest structure for the evaluation of a design or process,depending on the purpose for which the measuremen
37、ts are tobe used.9. Procedure9.1 Assemble the pulsing circuit shown in either Fig. 1 orFig. 2, so that a specimen can be connected via a suitable testfixture into the test circuit.9.2 Turn on all equipment, and allow the apparatus to warmup in accordance with the manufacturers instructions.9.3 Conne
38、ct the specimen to a suitable test fixture tomeasure the resistance of the specimen. If probes are used tocontact the specimen, see 5.2 for precautions.NOTE 7Appropriate handling precautions must be taken to preventelectrostatic damage.9.4 Measure and record the specimen resistance, in ohms orcontin
39、uity, as required.9.5 Connect an equivalent resistance into the pulse testingcircuit and, by applying pulses through this resistor, establishand record the pulser settings required to generate the pulseamplitudes to be applied to the specimen and the appropriatesettings for the pulse-monitoring equi
40、pment.9.6 Connect the specimen into the pulsing circuit.9.7 Set the current pulse generator and pulse monitoringequipment for a pulse of the designated amplitude and durationin accordance with the information recorded in 9.5.9.8 Apply a single pulse of the scheduled amplitude andduration to the spec
41、imen.9.9 Measure and record the specimen resistance (see 9.3 and9.4).9.10 Compare the value recorded in 9.9 with that recordedin 9.4. Characterize the specimen as failed if the resistance ofthe specimen has increased by the amount agreed upon by theparties to the test. Otherwise, characterize the sp
42、ecimen assurvived. Record the characterization.9.11 Repeat 9.3 through 9.10 for each specimen in thesample at each of the scheduled pulse amplitudes and dura-tions, and record the number failing, xtI, and the number tested,ntI, at each pulse amplitude and duration.10. Calculation and Interpretation
43、of Results10.1 Determine the safe operating region for general pulseduration, t, as indicated by Fig. 3. For each data point (t, I), asafe operating region includes all points falling below the curveIs(t) as follows:Ist! 5 Ittt, t $ twhere:t = test pulse width.10.2 If more than one data point (t, It
44、) has been established,the upper bound of the safe operating region is defined by thesmallest value of Is(t)atanyt as defined by all data points.NOTE 8See Appendix X2 for a method of extending these results toarbitrary pulse shape.11. Report11.1 The contents of the test report will vary depending on
45、the purpose of the test. The specific format and content for thereport (including the specific format in which the safe-operating area data is presented) are to be agreed upon by theparties to the test prior to the start of the test program.12. Keywords12.1 current pulse; current pulse burnout; meta
46、llizationburnout; safe current pulse; semiconductor burnoutFIG. 2 Pulsing Circuit Using Current Probe to Monitor CurrentThrough SpecimenNOTE 1The safe operating region is that region of the l, t plane belowthe solid boundary line.FIG. 3 Example of a Safe Operating RegionF 615M 95 (2002)3APPENDIXES(N
47、onmandatory Information)X1. METALLIZATION BURNOUT MECHANISMSX1.1 ScopeX1.1.1 This appendix describes the mechanisms involved inmetallization burnout, as addressed in the practice. This prac-tice deals with burnout failures that occur as the result ofcurrent pulses of less than 1-s duration.X1.1.2 Wh
48、en metal interconnections on semiconductorcomponents (semiconductor metallization) are damaged bycurrent pulses of such duration, the damage is generally a resultof resistive heating in the metallization (often at defect sites),which causes the metallization to melt, vaporize, or both.Semiconductor
49、metallization can also burn out as a secondaryresult of heating in the underlying semiconductor material.This practice and the following discussion are aimed atmechanisms associated with resistive heating in the metalliza-tion. The practice is intended to define safe operating regions inwhich such failures will not occur and is not intended todetermine the nature of any defect causing failure.X1.2 Equations of Resistive HeatingX1.2.1 When an electrically resistive material is subjectedto an electrical current, the differential equation for tempera-ture rise at any poi
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