6 crucial steps in semiconductor manufacturing - ASML

The entire process of creating a silicon wafer with working chips consists of thousands of steps and can take more than three months from design ... Weusecookiesforavarietyofpurposes,suchaswebsitefunctionalityandhelpingtargetourmarketingactivities.Somefunctionalcookiesarerequiredinordertovisitthiswebsite. Youcanwithdrawyourconsentatanytimeonourcookieconsentpage. Configureyourcookiesettingsandconfirmtosaveyoursettings.Youcanwithdraworchangeyourconsentatanytimeonourcookieconsentpage. Home News Stories 6crucialstepsinsemiconductormanufacturing Deposition,resist,lithography,etch,ionization,packaging:thestepsinmicrochipproductionyouneedtoknowabout 01/05 5-minuteread- JessicaTimings,October6,2021 Bynowyou'llhaveheardwordonthestreet:anewiPhone13ishere.Butit'sunderthehoodofthisiPhone–andotherdigitaldevices–wherethingsreallygetinteresting.That'swheretop-of-the-linechipslikeApple'sA15Bionicsystem-on-a-chiparemakingnew,innovativetechnologypossible.Sohowarethesechipsmadeandwhatarethemostimportantsteps? Wedon'tneedtotellyouthatmoderndigitaldevices–smartphones,PCs,gamingconsolesandmore–arepowerfulpiecesoftechnology.Muchofthispowercomesfrommicrochips,someofthesmallestbutmostdetailedpiecesoftechthatexist.Therearealotofmicrochipsaround(therecentchipshortage proveswecan'tgetenoughofthem!):In2020,morethanonetrillionchipsweremanufacturedaroundtheworld.That'sabout130chipsforeverypersononearth.Butdespitewhattheirwidespreadpresencemightsuggest,manufacturingamicrochipisnomeanfeat.Tomakeanychip,numerousprocessesplayarole.Let'sdiscusssixcriticalsemiconductormanufacturingsteps:deposition,photoresist,lithography,etch,ionizationandpackaging. IllustrationbyAadGoudappel Deposition Theprocessbeginswithasiliconwafer.Wafersareslicedfromasalami-shapedbarof99.99%puresilicon(knownasan'ingot')andpolishedtoextremesmoothness.Thinfilmsofconducting,isolatingorsemiconductingmaterials–dependingonthetypeofthestructurebeingmade–aredepositedonthewafertoenablethefirstlayertobeprintedonit.Thisimportantstepiscommonlyknownas'deposition'. Asmicrochipstructures'shrink',theprocessofpatterningthewaferbecomesmorecomplex.Advancesindeposition,aswellasetchandlithography–moreonthatlater–areenablersofshrinkandthepursuitofMoore'sLaw.Theseadvancesincludetheuseofnewmaterialsandinnovationsthatenableincreasedprecisionwhendepositingthesematerials. Photoresistcoating Thewaferisthencoveredwithalight-sensitivecoatingcalled'photoresist',or'resist'forshort.Therearetwotypesofresist:positiveandnegative. Themaindifferencebetweenpositiveandnegativeresististhechemicalstructureofthematerialandthewaythattheresistreactswithlight.Withpositiveresist,theareasexposedtoultravioletlightchangetheirstructureandaremademoresoluble–readyforetchinganddeposition.Theoppositeistruefornegativeresist,whereareashitbylightpolymerize,meaningtheybecomestrongerandmoredifficulttodissolve.Positiveresistismostusedinsemiconductormanufacturingbecauseitshigherresolutioncapabilitymakesitthebetterchoiceforthelithographystage. Severalcompaniesaroundtheworldproduceresistforsemiconductormanufacturing,suchasFujifilmElectronicsMaterials,TheDowChemicalCompanyandJSRCorporation. Lithography Lithographyisacrucialstepinthechipmakingprocess,becauseitdeterminesjusthowsmallthetransistorsonachipcanbe.Duringthisstage,thechipwaferisinsertedintoalithographymachine (that'sus!)whereit'sexposedtodeepultraviolet(DUV)orextremeultraviolet(EUV)light.Thislighthasawavelengthanywherefrom365nmforlesscomplexchipdesignsto13.5nm,whichisusedtoproducesomeofthefinestdetailsofachip–someofwhicharethousandsoftimessmallerthanagrainofsand. Lightisprojectedontothewaferthroughthe'reticle',whichholdstheblueprintofthepatterntobeprinted.Thesystem'soptics(lensesinaDUVsystemandmirrorsinanEUVsystem)shrinkandfocusthepatternontotheresistlayer.Asexplainedearlier,whenlighthitstheresist,itcausesachemicalchangethatenablesthepatternfromthereticletobereplicatedontotheresistlayer. Gettingthepatternexactlyrighteverytimeisatrickytask.Particleinterference,refractionandotherphysicalorchemicaldefectscanoccurduringthisprocess.That'swhy,sometimes,thepatternneedstobeoptimizedbyintentionallydeformingtheblueprint,soyou'releftwiththeexactpatternthatyouneed.Oursystemsdothisbycombiningalgorithmicmodelswithdatafromoursystemsandtestwafersinaprocessreferredtoas'computationallithography'.Theresultingblueprintmightlookdifferentfromthepatterniteventuallyprints,butthat'sexactlythepoint.Everythingwedoisfocusedongettingtheprintedpatternsjustright. Learnaboutlithography Etch Thenextstepistoremovethedegradedresisttorevealtheintendedpattern.During'etch',thewaferisbakedanddeveloped,andsomeoftheresistiswashedawaytoreveala3Dpatternofopenchannels.Etchprocessesmustpreciselyandconsistentlyformincreasinglyconductivefeatureswithoutimpactingtheoverallintegrityandstabilityofthechipstructure.Advancedetchtechnologyisenablingchipmakerstousedouble,quadrupleandspacer-basedpatterningtocreatethetinyfeaturesofthemostmodernchipdesigns. Aswithresist,therearetwotypesofetch:'wet'and'dry'.Dryetchingusesgasestodefinetheexposedpatternonthewafer.Wetetchinguseschemicalbathstowashthewafer.CompaniessuchasLamResearch,OxfordInstrumentsandSEMESdevelopsemiconductoretchingsystems. Chipsaremadeupofdozensoflayers.So,it'simportantthatetchingiscarefullycontrolledsoasnottodamagetheunderlyinglayersofamultilayermicrochipstructureor–iftheetchingisintendedtocreateacavityinthestructure–toensurethedepthofthecavityisexactlyright.Whenyouconsiderthatsomemicrochipdesignssuchas3DNANDarereachingupto175layers,thisstepisbecomingincreasinglyimportant–anddifficult. Ionization Oncepatternsareetchedinthewafer,thewafermaybebombardedwithpositiveornegativeionstotunetheelectricalconductingpropertiesofpartofthepattern.Rawsilicon–thematerialthewaferismadeof–isnotaperfectinsulatororaperfectconductor.Silicon'selectricalpropertiesaresomewhereinbetween.Directingelectricallychargedionsintothesiliconcrystalallowstheflowofelectricitytobecontrolledandtransistors–theelectronicswitchesthatarethebasicbuildingblocksofmicrochips–tobecreated.Thisis'ionization',alsoknownas'ionimplantation'. Afterthelayerisionized,theremainingsectionsofresistthatwereprotectingareasthatshouldnotbeetchedorionizedareremoved. Packaging Theentireprocessofcreatingasiliconwaferwithworkingchipsconsistsofthousandsofstepsandcantakemorethanthreemonthsfromdesigntoproduction.Togetthechipsoutofthewafer,itisslicedanddicedwithadiamondsawintoindividualchips.Cutfroma300-mmwafer,thesizemostoftenusedinsemiconductormanufacturing,theseso-called'dies'differinsizeforvariouschips.Somewaferscancontainthousandsofchips,whileotherscontainjustafewdozen. Thechipdieisthenplacedontoa'substrate'.Thisisatypeofbaseboardforthemicrochipdiethatusesmetalfoilstodirecttheinputandoutputsignalsofachiptootherpartsofasystem.Andtoclosethelid,a'heatspreader'isplacedontop.Thisheatspreaderisasmall,flatmetalprotectivecontainerholdingacoolingsolutionthatensuresthemicrochipstayscoolduringoperation. Wiliot,AyarLabs,SPTSTechnologies,AppliedMaterials:thesearejustsomeofthenamesinthemicrochippackagingbusiness,buttherearemanymore. Justthebeginning Themicrochipisnowreadytogettoworkaspartofyoursmartphone,TV,tabletoranyotherelectronicdevice.It'sprobablyonlyaboutthesizeofyourthumb,butonechipcancontainbillionsoftransistors.Forexample,Apple'sA15Bionicsystem-on-a-chipcontains15billiontransistorsandcanperform15.8trillionoperationspersecond. Ofcourse,semiconductormanufacturinginvolvesfarmorethanjustthesesteps.There'salsomeasurementandinspection,electroplating,testingandmuchmore.Andeachmicrochipgoesthroughthisprocesshundredsoftimesbeforeitbecomespartofadevice. Areyoureadytodivealittledeeperintotheworldofchipmaking?Discoverhowchipsaremade. Bethefirsttoknowaboutnewstories!  Signupfornewsalerts Abouttheauthor JessicaTimings Editor&writer BorninAotearoaNewZealandandbasedintheNetherlands,Jessicaisahumanitarianwhohaslaunchedintothetechindustry.Acuriousstorytelleratheart,sheisfascinatedbyASML’smind-blowingtechnologyandthepeoplebehindtheseinnovations. 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