英文翻译及文献电子电子功率半导体.docx

英文翻译及文献电子电子功率半导体.docx

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英文翻译及文献电子电子功率半导体

英文翻译及文献电子电子功率半导体

I.Introduction

Solidstatesemiconductorswitchesareveryinvitingtouseatpulsedpowersystemsbecausetheseswitcheshavehighreliability,longlifetime,lowcostsduringusing,andenvironmentalsafetyduetomercuryandleadareabsent.Semiconductorswitchesareabletoworkinanyposition,so,itispossibletodesignsystemsasforstationarylaboratoryusing,andformobileusing.Thereforetheseswitchesarefrequentlyregardedasreplacementofgas-dischargedevices–ignitrons,thyratrons,sparkgapsandvacuumswitchesthatgenerallyusenowinhigh-powerelectrophysicalsystemsincludingpowerlasers.

Traditionalthyristors（SCR）aresemiconductorswitchesmostlyusingforpulsedevices.SCRhassmallvalueofforwardvoltagedropatswitch-onstate,ithashighoverloadcapacityforcurrent,andatlastithasrelativelylowcostvalueduetothesimplebipolartechnology.DisadvantageofSCRisobservedatswitchingofcurrentpulseswithveryhighpeakvalueandshortduration.Reasonofthisdisadvantageissufficientlyslowprocessofswitch-onstateexpansionfromtriggeringelectrodetoexternalborderofp-njunctionaftertriggeringpulseapplying.ThisSCRfeatureisdefinedSCRusingintomillisecondrangeofcurrentswitching.ImprovementofSCRpulsecharacteristicscanbereachedbyusingofthedistributedgatedesign.Thisisallowedtodecreasethetimeoftotalswitch-onandgreatlyimproveSCRswitchingcapacity.Thus,ABBcompanyisexpandedthesemiconductorswitchusinguptomicrosecondrangebydesignofspecialpulseasymmetricthyristors（ASCR）.ThesedeviceshavedistributinggatestructurelikeaGTO.Thisthyristordesignandforcedtriggeringmodeareobtainedthehighswitchingcapacityofthyristor（

=150kA,

=50μs,di/dt=18kA/μs,singlepulse）.However,inthisdesigngatestructureiscoveredlargeactiveareaofthyristor（morethan50%）thatdecreasetheefficiencyofSiusingandincreasecostofdevice.

Si-thyristorsandIGBThavedemonstratedhighswitchingcharacteristicsatrepetitivemode.However,suchdevicesdonotintendforswitchingofhighpulsecurrents（tensofkiloamperesandmore）becauseofwell-knownphysicallimitsareexistedsuchaslowdopingofemitters,shortlifetimeofminoritycarriers,smallsizesofchipsetc.

Ourinvestigationhaveobtainedthatswitchesbasedonreverse–switcheddinistorsaremoreperspectivesolid-stateswitchestoswitchsuperhighpowersatmicrosecondandsubmillisecondranges.Reverse–switcheddinistors（RSD）istwo-electrodeanalogueofreverseconductingthyristorwithmonolithicalintegratedfreewheelingdiodeinSi.ThisdiodeisconnectedinparallelandinthebackdirectiontothethyristorpartofRSD.TriggeringofRSDisprovidedbyshortpulseoftriggercurrentatbriefapplyingofreversalvoltagetoRSD.DesignofRSDismadethusthattriggeringcurrentpassesthroughdiodeareasofRSDquasiaxiallyanduniformlyalongtheSistructurearea.Thiscurrentproducestheoncominginjectionofchargecarriersfrombothemitterjunctionstobaseregionsandinitiatestheregenerativeprocessofswitch-onforRSDthyristorareas.SuchmethodoftriggeringforthisspecialdesignofSiplateisprovidedtotalanduniformswitchingofRSDalongallactiveareaintheveryshorttimelikeasdiodeswitch-on.ThefreewheelingdiodeintegratedintotheRSDstructurecouldbeusedasdampingdiodeatfaultmodeinthedischargecircuit.Thisfaultmodesuchasbreakdownofcablelinescanleadtooscillatingcurrentthroughswitch..

IthasbeenexperimentallyobtainedinthatsemiconductorswitchesbasedonRSDcanworksuccessfullyinthepulsedpowersystemstodriveflashlampspumpinghigh-powerneodymiumlasers.ItwasshowninthatRSD-switchesbasedonRSDwaferdiameterof63mm（switchtypeKRD-25-100）andRSD-switchesbasedonRSDwaferdiameterof76mm（switchtypeKRD-25-180）canswitchthecurrentpulseswithsubmilliseconddurationandpeakvalueof120kAand180kArespectively.Threeswitches（switchtypeKRD–25-180）connectedinparallelweresuccessfullytestedunderthefollowingmode:

operatingvoltage

=25kV,operatingcurrentIp=470kA,andtransferredchargeQ=145Coulombs.

During2000–2001,thecapacitorbankforneodymiumlaseroffacilityLUCHwasbuiltatRFNC-VNIIEF.Thisbankincluding18switchestypeKRD-25-100operatessuccessfullyduring5yearswithoutanyfailuresofswitches.

Thisreportissubmittedresultsofdevelopmentofnewgenerationofsolidstateswitcheshavinglowlossesofpowerandhigh-currentswitchingcapacity.

II.DevelopmentofRSD’snextgeneration

ThetechnologyoffabricationofnewRSDstructurehasbeendevelopedtoincreasetheswitchingcapacity.ThisnewstructureisSPT（SoftPunchThrough）-structure-with“soft”closingofspace-chargeregionintobuffern'-layer.

Decreasingofn-basethicknessandalsoimprovingofRSDswitch-onuniformitybygoodspreadingofchargecarriersonthen'-layeratvoltageinversionareprovideddecreasingofallcomponentsoflossesenergysuchaslossesattriggering,lossesattransientprocessofswitch-on,andlossesatstate-on.OurpreliminaryestimationwasshownthatsuchstructuremustprovidetheincreasingofoperatingpeakcurrentthroughRSDapproximatelyin1.5times.

InvestigationswerecarriedoutforRSDwithblockingvoltageof2.4kVandSiwaferdiametersof63,76,and100mmbyspecialteststation.ThemaingoaloftheseinvestigationsisdefinitionofmaximumpermissiblelevelofpeakcurrentpassingthroughsingleRSDwithgivenarea.CurrentpassingthroughRSDandvoltagedroponRSDstructureduringcurrentpassingaremeasuredattesting.InFig.1waveformsofpeakcurrentsandvoltagedropsisshownforRSDwithsizeof76mmandblockingvoltageof2.4kV.

Fig.1.Waveformsofpulsecurrent（a）andvoltagedrop（b）forRSDwithwafersizeof76mmandblockingvoltageof2.4kV

InaccordingwithstudyprogramcurrentwasslowlyincreaseduntilmaximumpermissiblelevelIpm.WhenthislevelwasreachedthesharpriseofvoltageandthanthesamesharpdecayofvoltageforcurveU（t）wasobserved.Reasonofvoltageriseisstrongdecreasingofcarriermobilityathightemperature,andreasonofvoltagedecayisquickmodulationofchannelconductivitybythermalgeneratedplasmathatisappearedinaccordancewithsharpexponentialdependenceforownconcentrationofinitialsiliconintobaseareasofRSDattemperatureof400–

C.

TestswereshownthatthissharpriseofvoltageatmaximumpermissiblecurrentdoesnotleadtoimmediatefaultofRSD.RSDkeepsitsblockingcharacteristic.However,afterpassingofsuchcurrent

wecanobservetheappearanceoferosionfromcathodeforaluminummetallizationofRSDcontacts,andthisfactisevidenceofborderlinestateofdevice.Thesubsequentincreasingofcurrent（morethan

）leadstofusingofSistructure.Therefore,levelIpmisthereferencepositiontodefinethevalueofoperationpeakcurrentforRSD-switchunderlongandrepeatedmanytimesoperatingmode.

Wehavedeterminedthatoperatingpeakcurrent

mustbelessthan80%fromlevel

.Thisratiowasconfirmedbycalculationsandresultsoftestsunder

mode（severalthousandsofshots）.

DataoftestresultsfornewgenerationofRSDwiththevariousdiameterofSiwaferareshowninTable1.InthisTableforcomparingresultsofthesametestsforthefirstgenerationofRSDwithsizeof63and76mmareshown.

III.SwitchesbasedonRSDofnewgeneration

Newreverse–switcheddinistorsismanufacturedintwovariants.RSDofthefirstvariantisinthelow-profilemetal-ceramichousing.ThesecondvariantisRSDfabricatedwithouthousingandwithadditionalprotectionofperipheryareafromexternalaction.

Dinistorsplacedintohousingcanbeusedforworkunderasmono-pulsemodeandrepeated-pulsemode.Ifrepeated-pulsedmodeusingtheforcedcoolingofsemiconductordevicesandusingofheatsinkstobothsideofpelletmustbemade.Dinistorswithouthousingconnectsinseries,andsuchassemblycouldbeplacedintoasinglecompacthousing.However,suchassemblycanworkundermono-pulsemodeonly.

OperatingvoltageforswitchtypicallyexceedsblockingvoltageofsingleRSD（

≤2400V）,thusswitchisincludedseveralRSDsconnectedinseries.Fig.2.Reverse–switcheddinistorsforpeakcurrentfrom200kAto500kAandblockingvoltageof2400V,encapsullatedinhermeticmetal–ceramichousingandwithouthousing（RSDsizesof64,76,and100mm）.

NumberofRSDsincludedinassemblydependsonoperatingvoltageofswitch.Therefore,technicalproblemofswitchdevelopmentismainlyoptimizationofdesignforassemblyofseveraldinistorsconnectedinseries.AlotofspecialinvestigationshavecarriedoutsuchaschoiceofoptimummaterialstoprovidebestcontactsbetweenRSDs,calculationofdynamicforcestoclampassembly,etc.TheseinvestigationsareprovidedsmallandstabletransitionelectricalandthermalresistancesbetweenRSDsthatguaranteeslongandreliableperformanceofswitch.EspecialcomputertechniquehasdevelopedtoselectRSDsforconnectioninseries.AtthisRSDselectionvalueofleakagecurrentandstabilityofblockingvolt-ampsdiagramaremeasuredespecially.ThisselectiontechniqueisallowedexcludethevoltagedividersusingforequalizationofstaticvoltageforeachRSDatassembly.Thus,aftersuchselectionswitchdesigncansimplify,sizesofswitchareincreasedapproximatelyin1.5times,andcostofswitchisincreasedtoo.

Thissolidstateswitchhasoperatingvoltageofupto25kVdc,operatingpeakcurrentofupto300kAatcurrentpulsedurationofupto500μs.RFNC-VNIIEFplanstousesuchswitcha