三維集成技術(shù)的挑戰(zhàn)與解決方案

三維集成技術(shù)的挑戰(zhàn)與解決方案

前子區(qū)域的電子分銷(xiāo)市場(chǎng)是當(dāng)前的sec區(qū)域的開(kāi)發(fā)，它被推遲到了中日戰(zhàn)爭(zhēng)中的競(jìng)爭(zhēng)，以減少財(cái)政資源，以分散的微格式監(jiān)管機(jī)構(gòu)。在同一情境中，佳組件將被送到最小區(qū)域，而不是正輸入信息。Todaydifferent3DpackagingapproacheslikeSiP(SysteminPackage),SoC(SystemonChip)andSoP(SystemonPackage)havebeendevelopedinordertoanswertherequirementsforsmallerfootprint,shorterinterconnectsandhigherperformance.SiP“SysteminaPackage”isafunctionalsystemorsubsystemwithmultiplewire-bondedorflip-chipdiesinanICpackage.Othercomponentsareplacedonthemotherboard,likepassives,SAW/BAWfilters,pre-packagedICs,connectorsandmicromechanicalparts.Thistechnologyenablesastackedchippackagewithreducedformfactor.SoC(SystemonChip)integratesallthedifferentfunctionalblocks,likeprocessor,embeddedmemory,logiccoreandanaloginamonolithicway.Theseblocksarerequiredtointegratethesystemdesignonasinglesemiconductorchip.SoCdesignsusuallyconsumelesspowerandhavealowercostandhigherreliabilitythanthemulti-chipsystemsthattheyreplace.Andwithfewerpackagesinthesystem,assemblycostsarereducedaswell.SoP(SystemonPackage)usesthrough-viasandhighdensitywiringinordertoachieveahigherminiaturization.Itisanemergingmicroelectronicstechnologythatplacesanentiresystemonasinglechip-sizepackage.Where“systems”usedtobebulkyboxeshousinghundredsofcomponents,SoPsavesinterconnectiontimeandheatgenerationbyenablingafullsystemwithcomputing,communications,andconsumerfunctionsallinasinglechipThroughSiliconVia(TSV)hasevolvedasoneofthekeytechnologiesfor3Dintegrationandwaferlevelpackaging.3DTSVhasthepotentialtoonedayreplacewirebondingandthusenablefurthersizeandcostreduction,whichisoneofthebiggestchallenges,andincreasetheperformanceofthedevice.Today3DTSVtechnologyhasbecomecriticaltothegrowthof3Dcomponentsintegration,likememorystacking,orforMEMSstructurepackaging.ThefirstapplicationwhichisusingtheTSVasmainstreamtechnologyisthepackagingofCMOSimagesensors(CIS).ForCMOSimagesensors,WLPisalreadyanindustrialreality.Today,alreadyabout35%ofCMOSimagersensorscanbefoundintolatestconsumercell-phonesandnotebookcamerasareencapsulatedinaWL-CSPandthisnumberkeepsgrowing(Fig.1.)1u3000ethsmaskmostbecoatingOneofthetypicalprocessflowstoformTSVsisshowninFig.2.Thesestepsarerequiredforthroughsiliconviawaferprocessing.First,theetchmaskmustbecreated.Thisinvolvescoating,exposinganddevelopingthemask.Oncethemaskiscreated,theviascanbeetchedandinsulated.Viafillingcanthenbecompletedusingvariousmaterialssuchascopperandtungsten.Thefillprocessisdeterminedbythefillmaterials.Asoftoday,copperisthemostcommonlyusedmaterialforTSVs,butothermaterialslikeTungsten(W)orCu3Snalloyareusedaswell.2生產(chǎn)中心2.1u3000unizactinvi生物—ExposureandDevelopmentPhotolithographyofviaopeningsinphotoresistlooksprettystraightforward.However,thevariousfollowingprocessstepsanddifferentviasizesrequirespecificphotoresistexposureanddevelopmentconditionsandaskforanoptimizedsetofparameters.Typicallyviasizesdownto5μm(Fig.3)canbeeasilyandcosteffectivelyachievedby1Xfullfieldphotolithography.State-of-the-artresolutionlimitsareatabout3μminproximityprintingon300mmsubstrates.However,tightCDcontrolofviaopeningsrequiresaccurategapsetting,excellentlightuniformityandexposuredosecontrol.Allthiswillaffectthefinalexposureresultsandthereforeneedtobeaccuratelycontrolled.Forthedescribedexperimentatypicalviatestmaskhavingdifferentviadiameterswasused.TheSUSSMA300Gen2MaskAlignerprovidesanaverageintensityofabout90mW/cmThedevelopmentprocesswasagaincarriedoutontheACS300Gen2usinganaqueousdevelopmodulethatwasequippedwithabinaryspraydispensesystem.Thebinaryspraynozzlesetupandwater-jacketeddispenselinewithtemperaturecontroltopoint-of-useallowforreducingprocesstimesandminimizingmaterialconsumption.Variableratearmmovementacrossthewaferwasemployedinordertooptimizetheuniformityofthesprayprocess.Both,AZ4110andAZ9260weredevelopedusinga1:4dilutionofAZ400Kanddeionizedwater.TMAHbasedAZ726MIFwasusedforthedevelopmentofAZ1505.Thetrendforsmallerviasalsorequiresaccurateoverlayoftheprintresult.Overallalignmentperformanceofthemaskaligneraswellasrunouteffectsarethetwomainimportantfactorsthatinfluencetheoverlayresult.TheSUSSMA300Gen2usestwonoveltechnologiestoachievehighlyaccurateoverlay.Alignmentaccuraciesbelow0.5μm(3sigma)canbeachievedontheMA300Gen2byadoptingtheDirectAligntechnology.Firstofall,thesystemaccuratelyalignswaferandmaskinalignmentgap,whichistypicallysetto50～100μm.Thefinalhighaccuracyalignmentstepisperformedinexposuregap.Advancedpatternrecognitionsoftwaremeasuresandcontrolsthealignment,thusachievingsub-micronalignmentaccuracy.Alsoalignmentaccuraciesdownto0.25μmcanbeachievednowusingtheMA/BA8Gen3Maskaligner.ThenewOperator-assistedalignmenttechnologywithcontinuouslyautomaticcalculationofachievedalignment(X,Y,Θ)betweenbothtargetsallowsextremealignmentaccuracyassistedbypatternrecognition.DuringmanualalignmenttheCOGNEXDuringtheexperimenttheThermAlignchuckwassetto22℃.ThealignmentwasdoneusinganautomaticalignmentsystemindirectalignmentmodewithSUSSproprietaryalignmenttargets.Theachievedoverlaydataon300mmwaferareshownintable1andthex-yplotisshowninFig.5.2.2通過(guò)alnci反應(yīng)表tin,alinciperacunity,alinciper等域的alincipersonal.vhn.Oneofthemostimportanttopicsin3DStackingisthealignmentaccuracy.AscanbeseenfromtheroadmapshowninFig.6,thetrendofviasizesisthatviadiameterswillcontinuetoshrinkoverthenextcoupleofyears.Todayviadiameterinrangeof25～75μmareusedinCMOSImageSensorsdevices.InmemorydevicestypicallyfewmicronsdiameterisusedforaTSV.Forthewaferbondingtechnology,shrinkingviadiametershaveadirecteffectonthepostbondalignmentaccuracythatisrequired.Thereisalwaysaminimumoverlaprequirementsothatmetalviashavegoodelectricalconnectionwithminimizedresistance.Thisminimumoverlaprequirementdirectlytranslatesintopost-bondalignmentaccuracy,whichwillbeinthesub-micronrangewithinthenextcoupleofyears.Asbothofthewaferswhichneedtobealignedfor3DstackinghavemetallayersIRalignmentbecomesimpossible.AnotherapproachistheInterSubstrateAlignment.ThistechniqueiscapableofachievingtherequiredalignmentaccuraciesoutlinedinFig.6.Inthisalignmenttechniquespecialopticsareusedthatareinsertedbetweenthetwowafers.TheISAobjectives,onleftandright,imagethealignmentkeyontheupperandlowerwafersimultaneously.Thealignmentstagemovesthewafersandapatternrecognitionalgorithmperformsthealignmentaccordingtotherecipe.Aftertheobjectivesareretractedbothwafersmoveintocontactortoapredefinedgap.Typicallymovingthewafersinthez-axiscancreatesomemisalignment.Thereforenewprecisionopticsandmechanicshavebeencombinedwithglobalinlinecalibrationmethodstoachievesub-micronalignmentaccuracyintheBA300UHP(UltraHighPrecision)BondAligner.2.3il果報(bào)明整理劑案例5Waferbondingtechniquesusedfor3DStackingaremainly:-metaltometaldiffusionbonding(Cu)-metaleutecticbonding(Cu/Sn)-siliconfusionbonding-adhesivebonding(BCB)Therearealotofprosandconsforeachkindofbondingprocess.Whichonewillbechosendependsontheapplicationanditsrequirements.Howeverthereisacleartrendformetaltometaldiffusionbondingusingcopperasbondlayer.Theadvantageofthisbondprocessisthattheelectricalaswellasmechanicalconnectionisdonesimultaneously.2.4案例5.coviwolgace.coper-aluminum系統(tǒng)copeq/aluminum系統(tǒng)兩需要關(guān)于copeviration,3,3,4,4,4,4,4,4,4,4.,3.,3.,3.,3.,3.,3.,3.,3.,3.,3.,3.,3.,3.,5.4.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.3.Whentwometalsarepressedtogetherunderappliedforceandheat,theatomscanmigratefromlatticesitetolatticesitebondingtheinterfacetogetherSuchdiffusionprocessesrequireintimatecontactbetweenthesurfacessincetheatomsmovelatticevibration.CopperorAluminumareoptimalforsuchdiffusionprocessesduetotheirductilepropertiesandfastdiffusionrates.Copperbondingrequirestemperaturesintherangeof300℃upto400℃toachieveagoodhermeticallysealinterface.Theoxidationofcoppercanhamperthebondingprocess.Itcanbecrackedbyapplyingahighforceduringthebondingortoincorporateavaporcleaningprocesstoremovethesurfaceoxidation.Usingthevaporfromformicacid(HC00H)inabubbler,SUSSMicroTechasdevelopedapointofuseremovalsystemformetaloxides.Wafersareplacedincleaningchambersandexposedtothevaporforafewminutes.ThechamberispurgedandbycontrollingthepartialpressureofO2.5which-eth-si-ausiausiEutecticbondingisalsoofinterestfor3Dstackingduetothelowtemperatures,whicharebeginningat231℃forCu3Sn(Fig.7).ThusthemostoftenrequestedeutecticsareAuSn,AuSi,AlGe,andCuSn,asalreadymention.Italsorequiredtheusageofinertgastopreventoxidation.2.6u2004ain市直機(jī)關(guān)wafer-roinFusionBondingisinterestingfor3Dstackingduetotheveryshortprocesstimesandhighbondstrengths.Neverthelessduringthefusionbondingonlythemechanicalcontactiscreated.However,therearenodirectelectricalconnectionsacrosstheinterfacetointerconnectthemetallayers.Additionalprocessingisthereforerequiredtoetchthroughthewaferstackandbackfillviaswithmetals.Thisisdonebythinningoneofthesubstratestoseveraltensofmicrometersandfollowbyapatternedetchandmetalbackfillinaprocessknownas“vialast”processing.Thedrawbacktofusionbondingistherequirementsforsurfaceflatnessandroughness.Anotherissueisthelimitationintheannealingtemperatureduetotheusedmetalmaterialsinthewafers.Butusingplasmatreatmenttheannealingtemperaturecanbereducedfrom～1000℃downtotherequired200℃～400℃.Siliconfusionbondingneedsthefollowingprocesssteps:-plasmatreatmentcreatingahydrophilicsurfacewithaspecificchemistryandcontactangle-DIwatercleaningcombinedwithreactivationandbonding-temperatureannealinginastandardfurnace(batchprocess)2.7u3000e兩nb風(fēng)險(xiǎn)法上的alogening國(guó)際習(xí)慣法—AdhesiveBondingAdhesivebondingisveryoftenusedin3Dduetothelowrangeofprocesstemperatureandthetopographytolerance.Themostoftenusedpolymerforprecision3DadhesivebondingisBCB(benzocyclobutene)andisbondedfrom150℃～320℃.TheflowpropertiesofBCBcanbemanipulatedinordertoprovidelowtemperaturebondingandalignmentaccuraciesintherangeof1～2μm.BCBneedstobecoatedononeorbothwafers,theuseofadhesivepromoterAP3000isabsolutelyessential.BeforebondingtheBCBneedstobebakedout.Iftheprocuringisbelow150℃notallsolventsareremoved.Sothebondwillalmostcertainresultinapoormechanicalconnection.3wafertemperiek-roining網(wǎng)絡(luò)mask/waferr