芯片测试原理ppt课件

ICTestFundamental,GongXiao-Long2013,CourseContents,Lesson1:OverviewofICTestLesson2:Open/ShortandDCtestLesson3:FunctionalTestLesson4:TestVectorbasicLesson5:ADC/DACLesson6:ACtestingLesson7:Scan/Bist/JtagtestingLesson8:RFtestingLesson9:TestprogramDevelopmentLesson10:TroubleShooting,2,Lesson1:OverviewofICTest,TestcategoryTheTestSystemPMUPE-Card,3,Testcategory,WaferTestThetestingofindividualdeviceswhentheyarestillinwaferform.Thisisthefirstattemptatseparatinggooddicefrombad.Thisactivityisalsocalledwafersortordiesort.PackageTestWafersarecutintoindividualdiceandeachdieisassembledintoapackage.Thepackageddeviceisthentestedtoinsurethattheassemblyprocesswascorrectlyperformedandtoverifythatthedevicestillmeetsitsdesignspecifications.Packagetestisalsocalledfinaltest.QualityAssuranceTestPerformedonasamplebasistoinsurethatthepackagetestwasperformedcorrectly.DeviceCharacterizationDeviceCharacterizationistheprocessofdeterminingtheoperatingextremesofindividualdeviceparameters.Pre/PostBurn-InThetestingofdevicesbeforeandaftertheyareburnedintoverifythattheprocessdidnotcausecertainparameterstodrift.Thisprocessweedsoutinfantmortalitydevices(thosewhichhaveadefectthatcausesthemtofailsoonaftertheyarefirstused).,4,MilitaryTestingInvolvesperformingrigoroustestingoveratemperaturerangeanddocumentingtheresults.IncomingInspectionTestingofdevicesbyacustomertoinsurethequalityofthedevicespurchasedbeforeusingtheminanapplication.AssemblyVerificationVerifiesthatthedevicessurvivedtheassemblyprocessandthattheywereassembledcorrectly.Thetestsperformedduringassemblyverificationaresimilartothatofpackagetestingandmaybeasubsetofpackagetesting.Thisactivityisusuallyperformedoffshore.FailureAnalysisTheprocessofanalyzingdevicefailurestodeterminewhythedevicefailed.Determiningthecauseofafailureyieldsinformationthatcanimprovedevicereliability.,Testcategory,5,TheTestSystem,ThetestsystemiselectronicandmechanicalhardwareusedtosimulatetheoperatingconditionsthataDUTwillexperiencewhenusedinanapplication,sothatdefectivedevicescanbefound.ThetestsystemisoftenknownasATEorAutomatedTestEquipment.Thetestsystemhardwareiscontrolledbyacomputerwhichexecutesasetofinstructions(thetestprogram).Thetestermustpresentthecorrectvoltages,currents,timingsandfunctionalstatestotheDUTandmonitortheresponsefromthedeviceforeachtest.Thetestsystemthencomparestheresultofeachtesttopre-definedlimitsandapass/faildecisionismade.Atestsystemisactuallyacollectionofpowersupplies,meters,signalgenerators,patterngeneratorsandotherhardwareitemswhichallworkcollectivelyunderonemaincontroller.,6,TheTestSystem,7,TheCPUisthesystemcontroller.Itcontainsthecomputerwhichcontrolsthetestsystemandprovidesameansofmovingdataintoandoutofthetestsystem.Mostnewtestsystemsofferanetworkinterfaceaswellasmagneticmediafordatatransfers.TheharddiskandCPUmemoryareusedtostoreinformationlocally;thevideodisplayandkeyboardareusedbythetestoperatortointeractwiththetestsystem.TheDCsubsystemcontainstheDevicePowerSupplies(DPS),theReferenceVoltageSupplies(RVS)andthePrecisionMeasurementUnit(PMU).TheDPSsuppliesvoltageandcurrenttotheDUTpowerpins(VDD/VCC).TheRVSsuppliesvoltagereferencesforlogic0andlogic1levelstothedriverandcomparatorcircuitrylocatedonthepinelectroniccards.ThesevoltagessetVIL,VIH,VOLandVOH.LessexpensiveandoldertestsystemsmayhavealimitednumberofRVSsupplies,soonlyalimitednumberofinputandoutputlevelscanbeprogrammedatonetime.WhentesterpinssharearesourcesuchastheRVS,thatresourceisconsideredasharedresource.Sometestsystemsaresaidtohaveatesterperpinarchitecturewhichmeansthattheyhavetheabilitytosetinputandoutputlevelsandtimingindependentlyforeachpin.Atesterpin,alsocalledtesterchannel,iscircuitryonthepinelectronicscardwhichsuppliesand/ordetectsvoltage,currentandtimingforoneDUTpin.,TheTestSystem,8,Eachtestsystemhashighspeedmemory,calledpatternmemoryorvectormemory,tostoretestvectorsortestpatterns.Testpatterns,alsoknownasthetruthtable,representthestatesofinputsandoutputsforthevariouslogicalfunctionsthatthedeviceisdesignedtoperform.Input,ordrive,patternsaresuppliedtotheDUTbythetestsystemfrompatternmemory.Output,orexpect,patternsarecomparedagainsttheresponsefromtheoutputpinsoftheDUT.Duringafunctionaltest,vectorpatternsareappliedtotheDUTandtheDUTsresponsesaremonitored.IftheexpectedresponsedatadoesnotmatchtheoutputdatafromtheDUT,afunctionalfailureoccurs.Therearetwotypesoftestvectors-parallelvectorsandscanvectors.Manytestsystemssupportbothtypes.Thetimingsubsectionhasmemorytostoreformatting,maskingandtimesetdataforuseduringfunctionaltesting.Thesignalformats(waveshapes)andtimingedgemarkersareusedforDUTinputsignalsandstrobetimingforsamplingDUToutputsignals.ThetimingsubsectionreceivesdrivepatternsfrompatternmemoryandcombinesthemwithtimingandsignalformatinformationtocreateformatteddatawhichissenttothedriversectionofthepincardandthentotheDUT.SpecialOptionsincludesavarietyofpossibilitiessuchasalgorithmicpatterngeneratorsformemorytestorspecializedhardwaremodulesusedtoperformanalogtests.TheSystemClocksprovideameansofsynchronizingthemovementofinformationthroughoutthetestsystem.Theseclocksoftenrunatmuchhigherfrequenciesthanthefunctionaltestrate.Manytestsystemshavecalibrationcircuitrywhichcanautomaticallyverifyandcalibratethesystemtiming.,TheTestSystem,9,PMU,ThePrecisionMeasurementUnit(PMU)isusedtomakeaccurateDCmeasurements.Itcanforcecurrentandmeasurevoltageorforcevoltageandmeasurecurrent.SometestsystemshaveonlyonecentralPMUthatmustbesharedacrossallpinchannelsofthetester.OthershavemorethanonePMUwhichaccessesmultiplechannels,typicallyingroupsofeightorsixteen.HighendtestsystemshavePMUperpincapability,whichhasaPMUoneverytesterchannel.,PrecisionMeasurementUnit,10,ForceandMeasurementModesInATE,thetermforce(asinforcevoltageorforcecurrent)describestheapplicationofacertainvalueofvoltageorcurrentbythetestsystem.Applycanbesubstitutedforthewordforce.WhenprogrammingthePMU,theforcefunctionisselectedaseithercurrentorvoltage.Ifcurrentisforced,themeasurementmodeisautomaticallysettovoltage.Ifvoltageisforced,themeasurementmodeisautomaticallysettocurrent.Oncetheforcefunctionisselected,theforcevaluemustbeset.ForceandSenseLinesToimprovethevoltageforcingaccuracyofthePMU,afourwiresystemisused.Fourwiresystemsuse2forcelinestocarrycurrentand2senselinestomonitorthevoltageatthepointofinterest(usuallytheDUT).OhmsLawstatesthatavoltageisproducedacrossaresistancewhencurrentflowsthroughtheresistance.Allwirehasresistanceso,dependingonthecurrentthroughtheforcelines,thevoltageattheDUTisdifferentfromthevoltageatthePMUforceunitoutput.Using2separate(non-currentcarrying)sensewirestomeasurethevoltageattheDUTkeepsthevoltagedropcausedbycurrentflowthroughtheforcelinesfromcausinganerrororoffsetinthevoltage.ThepointatwhichtheforceandsenselineareconnectedtogetheriscalledtheKelvinConnectPoint.,PMU,11,RangeSettingsAPMUforcerangeandmeasurementrangemustbeselected.Properrangeselectioninsuresthemostaccuratetestresult.BeawarethattheforceandmeasurerangeshavealimitingeffectonthePMU.TheforcerangewilldeterminethemaximumforcingcapabilityofthePMU,soifthePMUisprogrammedtoforce5Voltsandthe2Voltforcerangehasbeenselected,only2Voltswillbeforced.Likewise,ifthe1mAmeasurementrangeisselected,themaximumcurrentthatcanbemeasuredis1mAregardlessoftheactualcurrentflow.ItisimportanttonotethatneithertheforcenorthemeasurementrangeofthePMUshouldbechangedwhileitisconnectedtoaDUT.ChangingtherangecausesnoisespikesthatmaydamagetheDUT.Anoisespikeiswhenasignallevelabruptlychangesitsvoltagelevelforaveryshorttime.Anoisespikeisalsocalledaglitch.LimitSettingsThePMUhastwoprogrammablemeasurementlimitsanupperandalowerlimit.Thelimitsmaybeusedindividually(onelimitenabledwhiletheotherisdisabled)ortheymaybeusedtogether(bothlimitsenabled).TheupperlimitisusedtomakeaFailGreaterThancomparisonandthelowerlimittomakeaFailLessThancomparison.FailingtheFailGreaterThanlimitmeansthemeasuredvaluewasmorepositivethantheupperlimitsetting.FailingtheFailLessThanlimitmeansthemeasuredvaluewasmorenegativethanthelower-limitsetting.,PMU,12,PMU,ClampSettingsMostPrecisionMeasurementUnitshavevoltageandcurrentclampswhicharesetfromwithinatestprogram.AclampisacircuitthatlimitstheamountofvoltageorcurrentthatissuppliedbythePMUduringatestinordertoprotectthetestoperator,thetesthardwareandtheDUT.,13,WhenthePMUisusedinForceVoltagemode,acurrentclampmustbesettolimitthemaximumcurrentwhichflowsduringthetest.Whenforcingvoltage,aPMUdeliversasmuchcurrentasnecessarytosustainthevoltage.IfaDUTpinisshortedtoground(oranothersupply),theforcingunitwillincreasethecurrenttotrytoforcethepintotheprogrammedvoltage.ThismayresultinalargeenoughcurrentflowthroughtheDUTpintoburnprobecards,circuittraces,pinelectronicscomponents,fingers,adjacentDUTs,etc.Whenforcingvoltage,thePMUmeasurescurrent.BecausethecurrentclamplimitstheamountofcurrentsuppliedbythePMU,thecurrentclampvaluemustbesetoutsideofthetestlimitsotherwisethecurrentclampwillpreventatoomuchcurrentfailure.PreviouspagesFigureshowsthePMUforcing5.0Vacrossa250Ohmload.Inactualtesting,theDUTistheresistiveload.FromOhmsLaw(I=E/R)weknowthatthe250Ohmloadwillrestrictthecurrentflowto20mAduringthistest.Thedevicespecificationmaystatethatthemaximumacceptablecurrentis25mA.ThismeansthefaillimitwouldbesettoFailGT25mAandthecurrentclampcouldbesetto30mA.IfadefectiveDUTpresentsaloadof10Ohms,theresultingcurrentwillbe500mAunlessacurrentclampisprogrammedtolimitthecurrent.Acurrentflowof500mAmaycausedamagetothetestsystem,theinterfacehardwareortheDUT.However,ifacurrentclampisprogrammedto30mAthemaximumcurrentflowwouldbelimitedbythedampcircuittoamuchsafervalue.Why30mA?youmayask.30mAisgreaterthanthefaillimitof25mA,allowingthetesttofailwhenadefectivedeviceisencountered,butthecurrentwillbelimitedtoasafevalue.Theclampvaluemustalwaysbesetoutsideofthefaillimits;ifnot,thetestwillneverfail.,PMU,14,Similarwithcurrentclamp,PMU,15,Thepinelectronics(alsocalledthePinCard,PE,PECorI/Ocard)istheinterfacebetweenthetestsystemresourcesandtheDUT.ItsuppliesinputsignalstotheDUTandreceivesoutputsignalsfromtheDUT.EachtestsystemhasitsownuniquedesignbutgenerallythePEcircuitrywillcontain:Drivercircuitrytosupplyinputsignals.I/Oswitchingcircuitryforturningdriversandcurrentloadsonandoff.VoltageComparatorcircuitryfordetectingoutputlevels.AconnectionpointtothePMU.Programmablecurrentloads.Possiblyadditionalcircuitryformakinghighspeedcurrentmeasurements.PossiblyaperpinPMUAlthoughtherearemanyvariationsofthisdesign,Figure3-5representsasingletesterchannelonatypicalpinelectronicscardforadigitaltestsystem.,PE-Card,16,PE-Card,17,TheDriverThedrivercircuitryreceivesformattedsignals,calledFDATA,fromthehighspeedsectionofthetestsystem.Asthesignalpassesthroughthedriver,theVIL/VIHreferencesfromtheReferenceVoltageSupplies(RVS)areappliedtotheformatteddata.IftheFDATAinstructsthedrivertodrivetoalogic0,thedriverwilldrivetotheVILreference.VIL(VoltageInLow)representsthemaximumguaranteedvoltagevaluethatcanbeappliedtoaninputandstillberecognizedasalogic0bytheDUTcircuitry.IftheFDATAinstructsthedrivertodrivetoalogic1,thedriverwilldrivetotheVIHreference.VIH(VoltageInHigh)representstheguaranteedminimumvoltagevaluethatcanbeappliedtoaninputandstillberecognizedasalogic1bytheDUTcircuitry.Whenthetesterchannelisprogrammedasaninput,FlFETturnsonandtheK1relayisclosedallowingthesignalfromthedrivertopassthroughtotheDUT.WhenthetesterchannelisprogrammedasanoutputorisinadontcaremodetheFlFETisturnedoffandthesignalfromthedriverwillnotpassthroughtotheDUT.TheFlFETisaFieldEffectTransistorusedasaveryhighspeedswitch.Itisolatesthedrivercircuitryfromthedeviceundertest.TheFlFETisusedduringIOswitching,whichiswhentheDUTalternatesbetweenreceivingdatafromthetestsystem(readingdata)andsupplyingdatatothetestsystem(writingdata).Thesamepinsfunctionasbothinputsandoutputs.Ifthetesterchannelisprogrammedasaninput,theFETison.IfthetesterchannelisnotprogrammedasaninputtheFlFETisoff,whichpreventsthedriversignalfromreachingthedeviceundertest.ItisimportanttoinsurethattheDUTandthedriverarenottryingtodriveavoltageontothesametesterchannelatthesametime.ThisiscalledanI/Oconflictoxbuscontention.,PE-Card,18,CurrentLoadsTheCurrentLoads,alsoknownasDynamicLoadsorProgrammableCurrentLoads,actasaloadtotheDUToutputsduringfunctionaltestsandcanbeprogrammedtosupplypositiveandnegativecurrents.PositivecurrentflowsfromthetestsystemintothedeviceandnegativecurrentflowsfromtheDUTintothetestsystem.ThedynamicloadsprovidebothIOH(CurrentOutHigh),whichistheamountofcurrentthataDUToutputmustsourcewhendrivingalogic1,andIOLcurrent(CurrentOutLow),whichistheamountofcurrentthataDUToutputmustsinkwhendrivingalogic0.AftertheIOLandIOHcurrentvaluesaresetbythetestprogram,theVREFvoltageisusedtosettheswitchingpointoftheIOLandIOHcurrents.TheswitchingpointistheoutputvoltageabovewhichIOHflowsandbelowwhichIOLflows.WhentheoutputvoltagefromthedeviceundertestismorenegativethanVREF,IOLcurrentflows.WhentheoutputvoltagefromthedeviceundertestismorepositivethanVREF,IOHcurrentflows.ThecurrentloadsarealsousedduringthefunctionalTri-Statetestsandthefunctionalopensandshortstest.TheF2FETisalsoafieldeffecttransistorusedasahighspeedswitch.TheF2FETisolatesthecurrentloadcircuitryfromthedeviceundertestandisusedduringIOswitching.Ifthetesterchannelisprogrammedasanoutput,F2ison,allowingcurrenttoflowtoandfromthedeviceundertest.Ifthetesterchannelisprogrammedasaninput,F2isoff.,PE-Card,19,TheVoltageComparatorsTheVoltageComparatorsareusedduringfunctionaltestingtocomparetheoutputvoltageofthedeviceundertesttoreferencevoltagessuppliedbytheRVS.TheRVSsuppliesareferenceforavalidlogic1(VOH)andavalidlogic0(VOL).IftheDUToutputvoltageisequaltoorlessthanVOL,itisrecognizedasalogiczero.IftheDUToutputvoltageisequaltoorgreaterthanVOH,itisrecognizedasalogicone.IftheoutputvoltageisgreaterthanVOLbutlessthanVOH,itisconsideredtobeaTri-Statelevelorabadoutput.ThePMUConnectionWhenthePMUconnectstoadevicepin,theK1relayisopenedfirst,thentheK2relayisclosed.ThissequenceisolatesthePMUfromtheI/Ocircuitryofthepinelectronicscard.TheHighSpeedCurrentComparatorsSometestsystemsofferawaytomeasuresmallcurrentsquicklyasanalternativetohavingaPMUforeachtesterchannel.Currentcomparatorsareusedtomakehighspeedleakagemeasurements.TheK3relayconnectsthecurrentcomparatorstothepinundertest.IfthetestsystemhasPMUperpincapability,thecurrentcomparatorsarenotnecessary.ThePPPMUSometestsystemsofferaperpinPMU(PPPMU)thatallowsthetestsystemtomeasureeithervoltageorcurrentoneverypinsimultaneously.LikethePMUthePPPMUcanforcecurrentandmeasurevoltageorforcevoltageandmeasurecurrent.PPPMUstypicallylackallthecapabilityofthestandardsystemPMU.,PE-Card,20,Lesson2:Open/ShortandDCtest,WhyTestforOpensandShorts?OpensandShortsSerialStaticMethodDCtestintroduce,21,WhyTestforOpensandShorts?,Theopens/shortstest(alsocalledcontinuityorcontacttest)verifiesthat,duringadevicetest,electricalcontactismadetoallsignalpinsontheDUTandthatnosignalpinisshortedtoanothersignalpinorpower/ground.Devicecostisdirectlyrelatedtohowlongittakestotesteachdevice.Oneofthebestwaystoreduceaveragetesttimeperdeviceistorejectbaddevicesassoonaspossible.Theopens/shortstestdeterminesveryquicklywhetheradevicehasshortedpins,missingbondwires,apindamagedfromstaticelectricity,amanufacturingdefect,etc.Theopens/shortstestcanalsopointtotestsystemrelatedproblemssuchasawafertestprobecardoradevicetestsocketwhichisnotmakingcorrectcontact.,22,OpensandShortsSerialStaticMethod,Testconditionsforanopens/shortstestarenotnormallydefinedinthedevicespecificationordatabookspecification,buttherearestandardvalueswhichapplytomoststandarddevicetypes.Thesestandardvaluesarepresentedintheguidelineshere.Totestforopens/shorts,firstgroundalldevicepinsincludingpowerandgroundpins.Next,connectthePMUtoasingledevicepinandforceacurrentwhichwillforwardbiasoneoftheprotectiondiodes.(SeeFiguresnextpage.)Anegativecurrentwillforwardbiasthediodetoground;apositivecurrentwillforwardbiasthediodetoVDD.Acurrentintherangeof100Ato500Ashouldbeadequate.Onceforwardbiased,thevoltagedropacrosstheprotectionstructurecanbesensed(typically0.65volt).Thesensedvoltagemaychangebetweenvarioustechnologiesanddesigns,but0.65Visgoodformostsiliconbaseddevices.SincethePMUwillbeprogrammedtoforcecurrent,avoltageclampmustbeprogrammedtolimitthevoltageproducedwhenanopenpinistested.Atypicalclampvaluefortheopens/shortstestis3V.Whenanopenpinistested,themeasuredresultwillbetheclampvoltage(3V).TheadvantageoftheSerial/StaticopensandshortstestisthatitproducesDCmeasurements.Whenafailureoccurs,theexactmeasuredvoltagemaybeexaminedfromthedata-loggedresults.Thevoltagevalueclearlyindicateswhetherthefailurewascausedbyashortedconditionoranopencondition.ThedisadvantageisthetimerequiredtomaketheindividualDCmeasurementoneachpin.,23,OpensandShortsSerialStaticMethod,24,25,DCTest-VOH/IOH,VOHrepresentstheminimumvoltage(V)producedbyanoutput(O)whentheoutputisinthelogic1(High)state.IOHrepresentsthecurrentsourcingcapabilities(I)ofanoutput(O)whentheoutputisinthelogic1(High)state.ThefollowingtableillustratestheVOH/IOHspecification,WhyTestforVOH/IOH?TheVOH/IOHtestmeasurestheresistanceofanoutputpinwhentheoutputisinthelogic1state.ThistestinsuresthattheresistanceoftheoutputmeetsthedesignparametersandguaranteesthattheoutputwillprovidethespecifiedIOHcurrentwhilemaintainingtheproperVOHvoltage.,26,VOH/IOHSerial/StaticTestMethodTheseparametersmaybeverifiedeitherstaticallyordynamically(dynamicVOHwillbediscussedlater).Toperformastatic(DC)test,thedeviceispreconditionedtosettheoutput(s)intothelogic1state,theDCmeasurementsystem(PMU)isconnectedtothepinundertest,theIOHcurrentisforcedandtheresultantvoltageismeasuredandcomparedtotheVOHspecification.IfthemeasuredvoltageislessthantheVOHlimit,thetestfails.Thisprocessisrepeateduntilallpinshavebeenverifiedinthehighoutputstate.Thistestmayrequirerunningmorethanonepreconditioningsequencetosetalloutputstothelogic1state.,DCTest-VOH/IOH,27,DCTest-VOL/IOL,VOLrepresentsthemaximumvoltage(V)producedbyanoutput(O)whentheoutputisinthelogic0(Low)state.IOLrepresentsthecurrentsinkingcapabilities(I)ofanoutput(O)whentheoutputisinthelogic0(Low)state.ThetablebelowshowsaVOLspecification:,WhyTestforVOL/IOL?TheVOL/IOLtestmeasurestheresistanceofanoutputpinwhentheoutputisi