碳纳米管计算机

CarbonNanotubesComputer〔CPU〕主讲人：姚鹏班级：微电子02

ThefirstdemonstrationsofcompletedigitalsystemsusingCNT！！！

Facingthephysicallimits：RobertColwell,formerchiefarchitectatIntel,predictedthatbyasearlyas2023,thecomputingindustrywillnolongerbeabletokeepmakingperformanceandcostimprovementsbydoublingthedensityofsilicontransistorsonchipsevery18to24months—afeatdubbedMoore’sLawaftertheIntelcofounderGordonMoore,whofirstobservedthetrend.

Facingthephysicallimits：“Wearewellawarethatsiliconisrunningoutofsteam,andwithin10yearsit’scomingtoitsend,〞saysZhirnov.〔VictorZhirnov,aspecialistinnanoelectronicsatthe

SemiconductorResearchCorporation

inDurham,NorthCarolina〕

Facingthephysicallimits：Althoughadvanceswithsilicon-basedelectronicscontinuetobemade,alternativetechnologiesarebeingexplored：nanowires,spintronics,graphene,biologicalcomputerNoonehasmadeacentralprocessingunitbasedonanyofthem，buttheCNTS。

THEBREAKTHROUGHTheachievementisreportedinSep.25,2023

inanarticleonthecoverofNature

MagazinewrittenbyMaxShulakerandotherdoctoralstudentsinelectricalengineering.TheresearchwasledbyStanfordprofessorsSubhasishMitraandH.S.PhilipWong

THEBREAKTHROUGH

THEBREAKTHROUGHMaxShulaker,doctoralstudentinelectricalengineeringatStanfordUniversity,holdsawaferfilledwithcarbonnanotubecomputers(CNTs).Tohisleft,abasicCNTcomputerutilizingthistechnologyissandwichedbeneathaprobecardtoinputandoutputsignals.Thisscanningelectronmicroscopy(SEM)imageshowsasectionofthefirst-evercarbonnanotubecomputer.Theimagewascoloredtoidentifydifferentpartsofthechip.

THEBREAKTHROUGHWhytheCNTScircuitsrepalacethesilicon?Digitalcir-cuitsbasedontransistorsfabricatedfromcarbonnanotubes(CNTs)havethepotentialtooutperformsiliconbyimprovingtheenergy–delayproduct,ametricofenergyefficiency,bymorethananorderofmagnitude.FasterCheaperSmaller

THEBREAKTHROUGHTheproblems：1：mis-positioned〔incorrectlogicfunctionality〕2：metallic〔incorrectlogicfunctionalityandhighleakagecurrents〕

THEBREAKTHROUGHTheproblems：1：mis-positioned〔incorrectlogicfunctionality〕Howtoputthemcorrectly？TheCNTSdon'tgrowinnicesmoothlines!

THEBREAKTHROUGHTheproblems：2：metallic〔incorrectlogicfunctionalityandhighleakagecurrents〕Currentlythehold-upisinfiguringouthowtogrowthemwithoutahigherrorrate.Thebestmethodscurrentlyproducenanotubesinbuncheswhereupto30percentofthemaremetallicinsteadofsemiconducting

THEBREAKTHROUGHTheapproach：NewProcessWongdevelopedamethodforgrowingmostlyverystraightnanotubesonquartz,thentransferringthemovertoasiliconsubstratetomakethetransistors.TheStanfordgroupalsocoversuptheactiveareasofthetransistorswithaprotectivecoating,thenetchesawayanyexposednanotubesthathavegoneastray

THEBREAKTHROUGHTheapproach：NewProcessWongandMitraalsoapplyavoltagetoturnallofthesemiconductingnanotubesonachipto“off.〞Thentheypulsealargecurrentthroughthechip;themetalliconesheatup,oxidize,anddisintegrate〔99.99%〕Therestofthemanufacturingprocess—canbedoneonthestandardequipment

THEBREAKTHROUGHVS

THEBREAKTHROUGHHowtodemonstrate：TheCNTcomputerrunsanoperatingsystemthatiscapableofmultitasking:asademonstra-tion,weperformcountingandinteger-sortingsimultaneously.Inaddition,weimplement20differentinstructionsfromthecommer-cialMIPSinstructionsettodemonstratethegeneralityofourCNTcomputer.

THEBREAKTHROUGHHowtowork〔ComparedwithIntel〕：TheCNFETcomputeriscomposedof178CNFETs,witheachCNFETcomprising,10–200CNTs〔尺寸：6.5平方毫米〕197dies〔5CNT〕computers

THEBREAKTHROUGHHowtowork〔ComparedwithIntel〕：4004处理器于1971年推出，尺寸为3mm×4mm，外层有16只针脚，内里有2,250个晶体管，它采用10微米制程。能执行4位运算，支持8位指令集及12位地址集。最高频率有740kHz。

THEBREAKTHROUGHHowtowork〔类似于取寻间执中〕(1)Instructionfetch(2)Datafetch(3)Arithmeticoperation(4)Write-back

THEBREAKTHROUGHTheSUBNEGinstruction

THEBREAKTHROUGH

THEBREAKTHROUGH

THEBREAKTHROUGH稳定

THEBREAKTHROUGHarithmeticunit

THEBREAKTHROUGHarithmeticunit

THEBREAKTHROUGHD-latches

THEBREAKTHROUGH一致

THEBREAKTHROUGHInputandtransform