集成基础电路 5

Unit5FromsilicontochipsViewingthroughthelensScriptsHowaresemiconductorchipsmade?Thejourneyofasemiconductorchipbeginswithsilicon,themostcommonlyusedmaterialforchipproduction.Siliconisderivedfromquartz,anaturalmineralcomposedofsilicondioxide.Thefirststepintheprocessispurifyingthesilicontocreatehighlypuresiliconingots.Oncetheingotisprepared,itispreciselyslicedintothinwafersusingadiamondsaw.Thesewafersarethenpolishedtoanatomicallysmoothsurfacetopreparethemforfurtherprocessing.Oncethewafersareprepared,theprocessofphotolithographybegins,whichisessentialforcreatingtheintricatecircuitsonthesemiconductorchip.Photolithographyissimilartophotography,wherealight-sensitivematerialcalledphotoresistisappliedtothewafer.Aphotomaskcontainingthecircuitdesignisplacedoverthewafer,andultravioletlightisshinedthroughit.Thelightexposesspecificareasofthephotoresist,changingitschemicalpropertiessothatselectedareascanberemoved.Thisprocessisrepeatedmultipletimeswithdifferentmaskstocreatemultiplelayersoftransistorsandinterconnectionsonthechip.Afterphotolithography,dopingandetchingareusedtomodifytheelectricalpropertiesofthesiliconandrefinethecircuitpatterns.Dopingistheprocessofintroducingimpuritiesintothesiliconwafertoalteritsconductivity.Thisisdoneusingionimplantation,wherehigh-energyionsarefiredatthewafertoembedthedesiredelementsinspecificregions.Oncedopingiscomplete,etchingisperformedtoremoveunwantedmaterial.Therearetwomaintypesofetching:wetetching,whichusesliquidchemicalstodissolvematerials,anddryetching,whichusesplasmatopreciselyremovelayers.Thecombinationofdopingandetchingdefinesthefundamentalelectronicpropertiesofthetransistorsthatwilleventuallyformthefunctionalpartsofthesemiconductorchip.Anothercriticalstepinsemiconductorfabricationisdeposition,wherethinfilmsofvariousmaterialsareaddedtothewafertobuildupthelayersnecessaryforthechip’sfunctionality.Thereareseveraldepositiontechniques,includingchemicalvapordeposition,physicalvapordeposition,andatomiclayerdeposition.Theseprocessesallowforthecontrolledadditionofmetals,oxides,andothermaterialsthatformtheconductiveandinsulatinglayersofthechip.Depositionisfollowedbychemicalmechanicalpolishing,whichsmoothsoutthewafersurfacebetweenlayerstomaintainprecisioninthecircuitdesign.Thisprocessensuresthateachnewlayerisevenlydistributed,preventingdefectsthatcouldinterferewiththechip’sperformance.Asthesemiconductorchipnearscompletion,interconnectionlayersareaddedtoenablecommunicationbetweenthedifferenttransistorsandcomponents.Thisisdoneusingaprocesscalledmetallization,wheretinycopperwiresaredepositedontothechipusingacombinationofphotolithographyandelectroplating.Theseinterconnectionsformthepathwaysthatallowelectricalsignalstotravelthroughthechip,enablingittoprocessandstoreinformation.Thefinallayersofthechiparecoveredwithprotectivecoatingstopreventcontaminationandphysicaldamage.Oncethewaferisfullyprocessed,itundergoesanextensivetestingandqualitycontrolphase.Ifthewafermeetsqualitystandards,itisdicedintoindividualchipsusingaprecisionsaw.Theseindividualchipsarethenpackagedtoprotectthemandfacilitatetheirintegrationintoelectronicdevices.ViewingandsynthesizingWhatstepsareinvolvedintheproductionofsemiconductorchips?Watchthevideoclipandchoosethecorrectstepstocompletetheflowchart.TheprocessofchipmanufacturingStepstochoosefromPurifyingthesiliconMetallizationDopingTestingandqualitycontrolDepositionAnswersBDFCEAWatchthevideoclipagainandanswerthequestionsbyfillingintheblanks.Howarethinwafersproducedfromasiliconingot?

Afterasiliconingotisprepared,itispreciselycutintothinwaferswitha(n).Howdoesultravioletlightaffectthephotoresistduringphotolithography?Ultravioletlighttargetsspecificregionsofthephotoresistandaltersits_____,allowingselectedregionstoberemoved.Whataretheworkingprinciplesofthetwotypesofetching?

Wetetchinginvolvesusingtobreakdownandremovematerials,whiledryetchingreliesontoeliminatespecificlayers.Whatisthepurposeofaddinginterconnectionlayerstoasemiconductorchip?Thepurposeistomakepossibleamongthevarioustransistorsandcomponents.Answersdiamondsawchemicalpropertiesliquidchemicals;plasmacommunicationViewinganddiscussingReferenceanswersFrommypointofview,photolithographyisthemostcriticalstageinsemiconductormanufacturingbecauseitsetstheresolutionandalignmentlimitsfortheentirechip-makingprocess.Duringthisstep,circuitpatternsaretransferredontothewaferlayerbylayer,creatingthepatternthatguideslaterprocessessuchasetching,deposition,andmetalinterconnection.Ifthepatternsarenotprintedclearlyoralignedaccurately,thesizeoftransistors,thespacingbetweentinycircuitstructures,andthepositionofinterconnectsmayallbeaffected.Theseerrorscanleadtoshortcircuits,opencircuits,leakagecurrent,orhigherpowerconsumption.Sinceadvancedchipscontainbillionsofextremelysmalltransistorsandrequiremanyrepeatedlithographysteps,eventinypatterningdefectscanaccumulateandreduceyield,performance,andreliability.Thisiswhyphotolithographyplayssuchadecisiveroleinchipmanufacturing.Manufacturersfacemajorchallengesinbalancingcost,efficiency,andqualitycontrolbecausesemiconductormanufacturingisextremelycomplexandcapital-intensive.First,advancedchipproductionrequiresveryexpensiveequipment,high-puritymaterials,andultra-cleanmanufacturingenvironments.Reducingspendingontheseareasmaylowercostsintheshortterm,butitmayincreasedefectratesandreduceyield.Second,manufacturersneedtokeepproductionlinesrunningefficientlytorecoverhugeequipmentcosts.However,fasterthroughputcanconflictwithcarefulinspection,processmonitoring,andreliabilitytesting.Ifqualitycontrolisreducedtoomuch,smalldefectsorprocessvariationsmayleadtolargelossesacrossanentirewafer.Third,aschipsbecomesmallerandmorecomplex,maintainingstableyieldbecomesharder.Manufacturersmustcontroltinyvariationsinlithography,etching,deposition,andpackagingwhilestillproducingchipsatscale.Together,thesefactorsaredeeplyinterconnectedandinfluenceoneanother,creatingsignificantchallengesforchipmanufacturing.ExploringthefrontierLanguagepointsHowever,semiconductortransistorsmadefromultrathin2Dmaterials,eachonlyaboutthreeatomsinthickness,couldbestackeduptocreatemorepowerfulchips.(Para.2)[Meaning]:Transistorsbuiltfromextremelythin2Dmaterials,onlymerelyaroundthreeatomsthick,canbelayeredtobuildstronger,moreadvancedcomputerchips.[Knowledgefocus]:2Dmaterials(seevideoclip)[Words&Phrases]:ultrathin:extremelythin超薄的e.g.Ultrathinmaterialscanbendeasilywithoutbreaking,soengineersusetheminflexiblescreensandwearablesensors.stack(sth.)up:makethingsintoaneatpile使……整齐地堆起e.g.Themetalplateswerestackedupandpressedtogethertoformastrongpanelstructure.Itconsistsofalayerofmolybdenumatomssandwichedbetweentwolayersofsulfuratoms.(Para.4)[Meaning]:Ithasonelayerofmolybdenumatomsplacedbetweentwolayersofsulfuratoms.[Words&Phrases]:sandwich:putsth.inaverysmallspacebetweentwootherthings使夹在……中间e.g.Alayeroftransparentmaterialissandwichedbetweenthepiecesofglass.Therefore,theresearchersstartedbythinkingoutsidethebox–theydesignedandbuiltanentirelynewfurnacefortheMOCVDprocess.(Para.6)[Meaning]:So,theresearchersbeganbytakinganunconventionalapproach–theydesignedandconstructedacompletelynewfurnacefortheMOCVDprocess.[Knowledgefocus]:MOCVD,ormetal-organicchemicalvapordeposition,isachemicalvapordepositiontechniqueinwhichvolatileprecursorsaretransportedintoareactionchamberandundergochemicalreactionsordecomposition,typicallyattheheatedsubstratesurface,toformthedesiredmaterial.Unlikephysicalvapordepositiontechniquessuchasmetalevaporationormolecularbeamepitaxy,wherematerialspeciesaresuppliedasatomicormolecularbeams,MOCVDintroducestheconstituentelementsintheformofgaseousprecursors.Theprecursorsareusuallycarriedbygasessuchasnitrogen,hydrogen,helium,orargonandareoftenkeptseparateuntiltheyreachthereactionzonetoreduceprematuregas-phasereactions.[Words&Phrases]:thinkoutsidethebox:findnewwaysofdoingthings,esp.solvingproblems（尤指解决问题时）打破思维定势，跳出窠臼e.g.Engineersmustthinkoutsidetheboxwhensolvingcomplexproblemsinmachinedesign.entirely:completelyandineverypossibleway完全地；彻底地e.g.Thismachineisentirelypoweredbysolarenergy,soitcanworkinremoteareas.Thiscirculationeffectimprovesthegrowthofmolybdenumdisulfideandleadstobettermaterialuniformity.(Para.12)[Meaning]:Thecirculatingflowhelpsmolybdenumdisulfidegrowmoreeffectivelyandproducesamoreuniformlayer.[Knowledgefocus]:Molybdenumdisulfide,oftenabbreviatedasMoS₂,isadarkgraytoblacksolidandoccursnaturallyasthemineralmolybdenite,theprincipaloreofmolybdenum.Theball-and-stickmodelbelowshowspartofthecrystalstructureofmolybdenite,MoS₂.Intermsofitsstructure,molybdenumatomsarepositionedbetweentwolayersofsulfuratoms,forminganS–Mo–S“sandwich.”ThislayeredstructuregivesMoS₂excellentelectronicandopticalproperties,makingitpromisingforuseintransistors.[Words&Phrases]:uniformity:thequalityofbeingorlookingthesameasallothermembersofagroup相同（性）；统一（性）；一致（性）e.g.Uniformityacrosstheconcretesurfaceensuresreliablestrengthandreducescracks.Thenewcapabilityforlow-thermal-budgetgrowthonan8-inchscaleenablestheback-end-of-lineintegrationofthismaterialwithsiliconCMOStechnologyandpavesthewayforitsfutureelectronicapplication.(Para.17)[Meaning]:Thenewabilitytogrowthismaterialon8-inchwaferswithalowthermalbudgetallowsittobeintegratedintotheback-end-of-lineprocessofsiliconCMOStechnology,openingthewayforitsfutureuseinelectronicdevices.[Knowledgefocus]:CMOS(seevideoclip)[Words&Phrases]:integration:theprocessofcombiningwithotherthingsinasinglelargerunitorsystem结合；融合；整合e.g.Theintegrationof3Dmodelsandtestdatahelpstheresearchteamfinddesignproblemsearly.pavethewayfor:makealatereventordevelopmentpossiblebyproducingtherightconditions为……铺道路；为……创造条件e.g.Thisdiscoverypavesthewayfornext-generationelectronicsbyhelpingengineersbuildfasterdevices.ReadingandpracticingReadingandsynthesizingReadthepassageandcompletetheoutlinewithinformationfromthepassage.TheurgencyfornewchipsAItoolsdrivetheneedfor1)______,higher-performancecomputerchips.Conventionalchipslimitmultilayerintegrationduetotheirrelianceon2)______,whichareshapedasboxy3Dstructures.MIT’schipsLayersof2D3)______materialsare“grown”directlyontopofafinishedsiliconchip.Thechosenmaterialforthisinnovativetechnologywasmolybdenumdisulfide,notableforitsflexibility,transparency,andpowerful4)______properties.Thegrowthreliedonaprocessknownas5)______.EngineeringchallengesandsolutionsTokeepcircuitssafe,researchersbuiltanew6)______withseparatehigh-temperatureandlow-temperaturezones.Toprotectthetopmetallayerfromreactingwithsulfur,athinlayerof7)______wasappliedontopofthechip.Toavoidheat‑induceddamageandachievebetteruniformity,thewaferwaspositioned8)______inthelow‑temperaturezone.Answersdenserbulkmaterialstransitionmetaldichalcogenide/TMDelectronicandphotonicmetal-organicchemicalvapordeposition/MOCVDfurnacepassivationmaterialverticallyReadthepassageagainandidentifytheparagraphfromwhichtheinformationisderived.Thesulfurprecursorbreaksdowninthehigh-temperatureregion,andtheresultingmoleculesreturntothelow-temperatureregion.The2Dmaterialmolybdenumdisulfideconsistsofasinglelayerofmolybdenumpositionedbetweentwolayersofsulfuratoms.Inthenewfurnace,neitherendofthesiliconwaferistooclosetothehigh-temperatureregion.Siliconcircuitsusuallyhavealuminumorcopperasthetoplayer,allowingthechiptoconnecttoapackageorcarrier.Usingtheirapproach,theresearchersmanagedtoproducealayerwithinanhour.Theresearchershopetoexploretheapplicationoftheirlow-temperaturegrowthprocesstoflexiblesurfaces.Twochemicalcompoundsareconvertedintovaporandheatedinthereactionchamberofthefurnace.Temperaturesexceeding550degreesCelsiusareneededtodecomposethemolybdenumandsulfurprecursors.AnswersPara.8Para.4Para.12Para.11Para.13Para.16Para.5Para.6CultivatingdisciplinemasteryFeaturesoftraditionalchipsandchipsutilizing2DmaterialsItemsforcomparisonTraditionalchipsChipsutilizing2DmaterialsIntegrationpotentiallimitedstackingeasierlayerstackingThermalstabilityoverheatingrisklowerheatperlayerPotentialapplicationmainstreamlogicandmemoryfuturehighdensity3DchipsDevelopmentstagemassproductionearlyresearchstageFunctionallanguageExpressingdifferences:Thedifferencebetween...and...liesin…Akeydistinctionbetween...and...isthat…...differsfrom...inthatit…...focuseson…while...emphasizes…...and...varysignificantlyintheirapproachto…...and...aredistinctintermsofhowthey…...ischaracterizedby…whereas...isdefinedbytakesadifferentapproachcomparedto...ReferenceanswersAraditionalchipsandchipsutilizing2Dmaterialsdifferinseveralways.Traditionalchipsarebasedonbulkmaterials,sotheirstackingpotentialislimited,andoverheatingismorelikelytobecomeaproblemindensestructures.Theyhavealreadybeenwidelyusedinmainstreamlogicandmemoryandhavereachedmassproduction.Bycontrast,chipsbasedon2Dmaterialsalloweasierlayerstackingandcouldhelpreduceheatgenerationperlayer,whichmakesthempromisingforfuturehigh-density3Dchips.Nevertheless,comparedwithtraditionalchips,2D-material-basedchipsarestillintheearlyresearchstageandhavenotyetreachedlarge-scalecommercialproduction.Traditionalchipmanufacturingisfacinggrowingchallengesasdevicesshrinkandbecomemoredenselyintegrated,especiallyinheatdissipation,powerconsumption,andperformancestability.Two-dimensional-material-basedchipsofferapromisingpathtowardfuturehigh-densityintegration,buttheirlarge-scaleproductionalsofaceskeychallenges.Whenintegratedwithexistingsiliconcircuits,2Dmaterialsusuallyneedtobeprocessedatlowtemperaturestoavoiddamagingtheunderlyingcircuitry,makingprocesscontrolmoredemanding.Chemicalreactionsduringgrowthorlaterprocessingmayalsoaffectnearbymetallayers,soprotectiveorbarrierlayersareoftenneeded.Inaddition,2D-materialprocessesmustbecompatiblewithexistingsemiconductorproductionlines,includingestablishedprocessflows,equipmentplatforms,andcontamination-controlstandards,withoutreducingyieldordisruptingconventionalsiliconchipmanufacturing.Translationofthetext麻省理工学院工程师在芯片上“培育”原子尺寸晶体管新兴的人工智能应用，比如能生成自然语言的聊天机器人，需要更高密度、更强性能的计算机芯片，但传统半导体芯片由体积庞大的块状三维结构材料制成，因此堆叠多层晶体管以实现更高的集成度是极为困难的。不过，可以堆叠由超薄二维材料制成的半导体晶体管（每层厚度仅约三个原子）来制造性能更强的芯片。为此，麻省理工学院研究人员现在展示了一种新技术，这种技术能够高效、直接地在已经制造完的硅芯片上“培育”二维过渡金属二硫化物材料层，从而实现更高的集成度。该研究团队一名成员、这项新技术相关论文的共同第一作者表示：“使用二维材料是提高集成电路密度的有效途径。我们正在做的事情就像建造一栋多层楼房。如果只有一层，也就是传统情况，那么它容纳不了多少人。但有了更多楼层，这栋楼就能容纳更多能制造出令人惊叹的新事物的人。借助我们正在研究的异构集成技术，我们可以把硅作为第一层，然后在其上方直接集成多层二维材料。”研究人员重点研究的二维材料二硫化钼，兼具柔韧性与透明性，且拥有出色的电子和光子性能，是制作半导体晶体管的理想材料。它由一层钼原子夹在两层硫原子之间构成。在均匀度较好的表面上培育二硫化钼薄膜，通常通过金属有机化学气相沉积过程实现。两种汽化后的分别含有钼原子和硫原子的化合物，在反应室内受热，“分解”为更小的分子；这些分子随后通过化学反应连接起来，在表面上形成二硫化钼。然而，这些被称为“前驱体”的钼化合物和硫化合物，分解温度需超过550摄氏度，而硅电路在温度超过400摄氏度时就会开始分解。因此，研究人员开始跳出常规思路，设计并建造了一台全新的金属有机化学气相沉积炉。该炉体有两个腔室：前端为低温区，用于放置硅晶片；后端为高温区。汽化后的钼前驱体和硫前驱体被泵入炉内，钼前驱体留在低温区，那里的温度控制在400摄氏度以下——这个温度足够分解钼前驱体，又不会损坏硅芯片。硫前驱体流入高温区并分解为更小的分子，随后这些分子回流至低温区，在硅晶片表面发生化学反应，从而“培育”出二硫化钼。研究人员解释道：“你可以把分解想象成磨黑胡椒——你有一整粒胡椒，要将它磨成粉末状。那么，我们在高温区把胡椒碾碎、磨细，然后粉末再流回低温区。”然而，当这种有前景的方法用于制造完的硅芯片时，也会带来新的挑战。因此，研究人员进一步作出调整，以完善他们的技术。这项工艺存在一个问题。硅电路的顶层通常是铝或铜，用于在芯片安装到印刷电路板之前，将芯片与封装或载体连接起来。但硫会使这些金属发生硫化，如同氧气会使一些金属生锈一样，而这一过程会破坏它们的导电性。研究人员先在芯片顶部沉积一层极薄的钝化材料，防止硫化，后续再打开钝化层以建立连接。他们还将硅晶片垂直放入炉体低温区，而非水平放置。垂直放置可避免硅片两端过于靠近高温区，因此硅晶片没有任何部分会因受热而损坏，同时，气体分子在撞上垂直放置的硅晶片时形成旋流，而非流过水平表面。这种环流效应改善了二硫化钼的培育质量，提升了材料的均匀性。除了获得更均匀的材料层，研究人员的方法还比其他金属有机化学气相沉积工艺快得多。他们可以在不到一小时内培育出一层，而其他金属有机化学气相沉积培育工艺通常至少需要一整天。借助最先进的设施，研究人员在八英寸硅晶片上实现了高均匀性、高质量的培育，这对需要较大尺寸硅晶片的工业应用尤为重要。通过缩短培育时间，该工艺的效率大幅提高，也更容易融入工业化制造流程。此外，该工艺具备低温、硅兼容的特点，这使其在推动二维材料进入半导体产业应用方面尤其具有吸引力。未来，研究人员计划优化该技术，将其用于培育多层堆叠的二维晶体管。他们还想探索低温培育工艺在柔性表面，如聚合物、纺织品甚至纸张上的应用，这有望把半导体集成到衣物、笔记本等日常物品上。该领域的研究人员指出，这项工作是单层二硫化钼材料合成技术的重大进步。这种在八英寸规格上实现低热预算培育的新能力，使该材料能够在后道工艺中与硅基互补金属氧化物半导体技术集成，为其未来在电子器件中的应用铺平了道路。

ShowcasingChina’stechadvanceScriptsAdvancingphotonicchipmanufacturingwithlithiumtantalateScientistsinChinaareexploringacost-effectivemethodforthelarge-scaleproductionofopticalchips.Thesechips,knownasphotonicintegratedcircuits(PICs),usephotonsratherthanelectronstoprocessandtransmitdata.PICstypicallyintegratealargenumberofphotoniccomponentsandarewidelyusedinfiberopticcommunicationsandphotoniccomputing,anemergingtechnologythathasthepotentialtoincreaseprocessingspeedswhilereducingenergyconsumption.Owingtotheseadvantages,photonicchipsalsohavebroaderapplicationsinareassuchasdataprocessingandthelifesciences.PICscanbefabricatedusingvariousmaterials,includinglithiumniobate,whichisvaluedforitsstablemechanicalproperties,easeofprocessing,hightemperatureresistance,corrosionresistance,andreadilyavailablerawmaterials.Thematerialalsoexcelsatconvertingelectricalsignalsintoopticalsignals,acrucialaspectoftheelectro-opticalconversionprocess.However,theindustrialapplicationofthistechnologyishinderedbythehighcostperwaferandthelimitedwafersizes.AteamattheShanghaiInstituteofMicrosystemandInformationTechnology,workingwithresearchersfromtheSwissFederalInstituteofTechnologyinLausanne,hasreportedlow-lossPICsmadefromlithiumtantalate.Thematerialhasalreadybeenadoptedcommerciallyfor5Gradiofrequencyfilters