JpAJIESEThULOrlpl,LJEDPHYSJCSVr)L.29,Nn..r;FTITtURY.1990.pp.Ll95-L197

DependenceoflJleCarrierCorleerLtmtiorlProLiJeateSi

ME Layer/p-SiSubstrateh tereOneSiSubs te

PrepaFalfjonMetTIOd

HjTOyukiKlNAY,HjdeTnjSHIGAWA,Fumio~H sECjWandEjsoYAK 1

/JzsriIL/(eOfiVL7(CrI'dIScieltCe,ult)le7yOJ-Tszll,lLbu.

7hli.tJ/)aScJ'eIEreCil305

.Tsui'LJbuCollegea/TechJtO/0&V,Tstll'Ltb"Su'FrCeCJZy305

(ReceivedNovemberlOJ989;EICtedforpllbliealLOll.Ja1111ary1l,1990)

TllemfluececrtheSisulJSLFalepTeParalior1methodontecITTierconetra10TrOr.I,e;IlTheSiML3Ehycr/SIsubslJatPinlerrace"ra5Stu(lied.llwasrOtindHlilLlhcSJ-SubsLraLeShollldbepLaccdjn1LIUTiVMBEi.hBmbe1medi-alCLy(1LllillminuleS)rTerremovaorLheoxideLa)reftodizllinaLelleP+izltCrraCClayerandmustbehc.lledupTO250oCbef()TeMllEgrovlh,inorderlopreventcaTricrdepletjollatlheinleTraeeandalso10ObLalnSOO)/-I/C.haracICrji-1icadiodewilaSHjcidC/P-Sl'(OISiGe)hFIBElayer/p-SisubsILaLeSLruClurC.

KEYWORDS:SISiGemoJecularbeamepitaxy,oxidePaye._carrierCOnCenlralionproe.intere)ce.Schotlkydiode

$1, tntJ'OduL-tjorL

APtSi/p-SiSchoLlkycotltaetisnovusedforaLarge-

scalelRimagesellSOrinthewavelellgthrallgeOf3-5

Flm.HsilleetheabsoTpLionorinrraTed(]R)radiationintheaIlt]()SpherejsverysulallinthewaelengLhrangeor

8-1211.andtheradiELtionpeakoftheobjectaHOOtlltemperatureisarold011,anIRimagesensorfortllislong-"avelertllrarejsveryJrnpoTt-anL,Tbererore,fur-

lhcrextcllSiortoltheeutoWavelengt11isurgentlyneeded

especiallylntheweathersateHiteneld)WehavebeenstudyingPl/p-SiHGe.L/p-SiSchotlky

conldCtSainlir ataLongerwae)engthrRsensoralld

havedemonstratedthattheSehoHkybarrierheightscallbereducedbyillCreaSlngtheGeFraction,3)oneortheobstacLeloJ.eaJizatioLl0aPt/-Sil_rGeLIRsensorisa

lowbreakdowIIVOLtageorthePL/p-SiI-,Ge,Schouky

diodes.lI1OrdertorealizeaguardriT]gStuCttreforthe

lOfl11rangeCCD imageserlSOTillthefutureand toutj]izeastrainedSjGelayer,4)theepitaxjallayershould

beasthinaspossjble.ltwasreported.however,thatap-

LypehighcarriereoncentratioJl(1017-1Ocm--1)region

orlCnPeaJl.SaLtJleterfacebetwee1theSiMBflayer

andp-typeSisubslraLe ThjShighCarriercollCeLltTt-

tionLayermlLS(innuencethebreakdowTl0ageofthe

Pt/p-Si..lGeJp-SisubstraleScllOtLkydiodeswhendleepjtaxiaHayeristLliJ).

Kubiaketa/.reportedulaHltisheavilyp-typelayerattheinleTraCeWasrOrtnedby1)orotlintroducedfromthe

borosuieateglassofHleVieOrtintheMBEsysICm.j)

01theotherhald,Casele/a/.demonslraledastTOIlg

dependenceortheLTlt_erraCeP+Layerontheexisle1-CeOl

the.surfaceo,yide)aycroftheSisubstrate.611tiswidelyac-ceptedthataCareruuyPrepal'edsurraceoxidelayerisin-

eyi(ableIoobtainahigJlqualitySiMBEayer.71llist101yetknowllhow tocompromisethesetwoCOnnicting

pheDOmeTla;tlleOXidelayeristleCeSSaryForahighquali-

tyMElayer,butiti1trOdtlCeSaBoron-dopedp+layer

L195

attheinterface.

ThepllrPOSeOfthisworkistohldaprepa'ationa]1d

cleaningmethodloTtheSjsubstJatetOObtainahigh

quali_tySiandSiGcMBElayerwiLhouLlhcp+erfaee

regionattlleePi-substJateinterface.

2. Eerimental

MBElayersweregrownonp-type(100)CzochralskiSi

substraLeStP=3-510Mcm~Ll).ThebasepressLLreOfthcMBEsystem vasabollL3XLO-1TorTaudthatorlhcload lock erlamber Was about 10~7Torr.Sjwas

evaporatedbyanE-gtInandGe.byaK-cell.TheSianJdGemOleclllarbeasWereCOroucdbylnOnirorillgWith

allelectronhlaCtenliss-ionspecLfOSCOPy(EIES)selSOr.sHayersveregro,nat750oCatarateof1.5A/S.SiGeLayersveregTOWllat550oCaarateor1.5-2.OA/.

ThepressuredurjugthegrowLltWaS 3xIO-1)Torrr

TlleBoronwasdopedinbothLayerswithHBO2.The

subsrateculin2cmsqlLareS~WaSPreC)eatledbythetlSuaLrshika-Shirakimethod.7'Forsomesubstrates,the

passjvalionoxidelayerswerecompctelyremovedbyadilutedHF(0.5%)soIuLionbeforethesubslraleSWere

placedintlleMBEchamber.ThesllbstrateintheM13E

cIlambefWasheatedLLPtOabotlt85()oCtoevaporatethe

surraceo,yide)aycrbcrorel7leSigrowth.lnsomecases,thesubstJateWEISheatedup(012.500CloTeulOVetileCAbollOlH hesubs(rate.CarriercollCentratjollPrOIesat

thejnterracewerecaleuja(.ed frotllthecapacjtance-

voltage(C-V)characteristicsmeasuredbyaTiSchoukycontact.

3. RcSuHsaTtdDjsSSion

Becausefubiakel(JJ.repol.I,edthattheaccL)mLllalion

orBoronattheSiepi-SubstrateinteracewasTelaLedto

thethjckIeSSOrthepassivatioll0Kidclayer,weRTStin-

vestigateddependenceoftheBoronaccumuLaLionon(hethicknessoftheoxidelayer.AterrorlnationorthepassivatjoIOXidelayerbylshilZakaShirakimethod,tJle

l

LM6 Hiro)ruklKNY .Tii(knliSilLG W.FunlloHLlECmandEjiOY lk,

oxidelayerVaSthinnedbyadilutedHFI.SOlution(0.5%).andSisubslrateSWiththreedjqcrcnlOXide)ayers(0.

-5,-15A)wererol'med.

Figure1shosthecarrierconer)tralionprorllLISalthe

MBESilayer/pISisubslrateinlerlaces.Arowsinllle

fi_uLlrleindicatepositionsor(heWBESilayer/p-SiSubin-

Lerraccs.TheLbjck1eSSOftheoxidelayerorsaJllPleA

Waszero.thatorsampLeBWaSabout5andnat0rSam-

pJeC("rhoseoxidelayerwa.inotremovedbythedilutedHFsolutioll)wasabout15A.TheLhjekleSSOrtheoxidelayerwastjmatedbylheetelmi grateOrtheo,Videlayer.

SampleAllTaSPJacedl'ntheUH~VMBEehanlberWithjl110minutesarte1-remova0rLheoxideLayer,Withoutrins-

1nglnWaferI-Oavoido,yidationor(_hesLLbstratesurface

b),thewater_S(lmPlesBandCwereTjnsedinWaterafter

etchingbythedilutedHF.TheseSamplesWereheatedto

e-vaporatetheoxjdelayers.SampleA sho.eda2

RHEEDpaHe a1400oC,sampleBshowedjlat680oL-andsaruplcCshoweditat85OoC.NoSicRHEEDpat-ternwasobservedForLhcscsamples.SanlpJcsBalldC

showalmosHhesalTleheight()rthecarl.iercollCel1tration

peakjnFig.I,but5ampleAdoesUOLTheselesuLISizdicatetllattJICpLlayeraHheinterfacecanbeleducedby

remolLtgtheoxideJayerasrepor(edbyCaseJetaJ.61llisnotwellknownWheretheBoroncomesfrom.ltmightbe

From borosi)icaleglass/IbutothercalldidaLesaretlle

substrateand(,llmospllereitself.lnanycase,whenlhcox-

idelaycreJYisLS,theT3oroui.sthoughHoaccutnulateiTHheoxidelayerrroTnthesurroundingsandtobelerIOnthe

sub.slraleSurfacewhentheoxidelaveriSevaporate(1.

WhentlleOXidepassivationfilm WaslllillnedbythediltltedHFtheSicRHEEDpatlem WasOrtet]Observed

oJlthesurfacewhentheSjsubstralCWasheatedupto

aboe750oC.FjgL)re2ShowslflCCarrierconccntralionpronJealtheSiMBELayer/l)-Sisubstraleinterraccsor

(C

5/NOllVtJL

NuUNO3-

V3

1d5DEPTHFROM 5U,RFACE

(Hnl)

Rs.,CarrjcrcollcLelfraHor)prOr12esilltheSilVIL3Elaye-/p-SisubstrIleinlCTlilCeS.The.thlCknLlSSCOfoxidelayerereaSrOHoWs:StlnlPleA Ze)0.BvllS5dCw;lSI_5.

I(

eEUL/Ft)NOLLy

NuU.NO3

I,

V3

7

6

10t

1d0 .1 .2 ,3 .4 .5

DEPTH FROM SURFACE

(Hm)

FLR.2CarrierconLlltricPrOrlle.iaLtheSMJjEJFt)el/p-SSuhll1--errneeThelhjc-i,nesscsoroxidelayersrLH lirOHovs:snnlplFAlvaszero.BaTldCL'wcrL15A.JuJorl)1cmrLkLIptllt71elo,d-1(lCi.chaTTtbertor2hours.

theslmPLc.sonWhichtheSicRHEEDPaHernSWeTCOb-served.Tllethicknessoftheo;(idelJdyerOrSampleAill

Fig.2aszero:lhoseorBandCWeTeabout5A.Auor

lhcmWerekepththeload-ockcllamberO-7TorT)roT

2hoursbeforebeingheatedI)ptoS500CintheUuV

JMBEcllambertoevaporatetheo,tideLayer.TheinLen-

sjtiesoftheSic RjjEEDpauer11SOfsa111PLesAandC

werestTOlerthanLhaLOrSampleBDepletjonregiollS

o1ccarrierappealLedaltheMBElayeSllbSlra(ei1tCr-

racesroIausamp)es.TlleCat)SeOrthedepkLionregion

wasthoughtLobesomedefect.sintheMBEgrownlayerWhichwereintJOdLLCedbySic()lHhesllbstratesurface.

ForsarnpIeA,a2x1RHlEDpatternWas1101ObserveduntHthestlbstratetemperatllTeOf650cc,atttlOughttleOX-

idelayerWascornplctclyI:e10Ved.Thisi.sprobablydue

tofoTmatjonoftheo,yidelayeroraFewAwhilethesam-

plewaskeptintheload-)ockchamberfor2110urS.ThusbothadL,plelionandahighcarrierconcenlTalioLIL'egion

appearedinsampleA.Tniteortheoxidelayerexisllng

itlSatllp)csBandC,thehigllCaTriereollCenlralioIITeglOn

didl10Lalear.ThisisprobablyduetotheracHhaLthediodebreakdoWr10ccurrSbeforethedepLclion layer

reachestothehgtlCarriercollCenlrationregLOn.

To elarify the OTigiZOflhc depletion layer,Si

sLLbstrate.qwerehealedupto1250oCtoeaporateCar-bonontheslbstratesurraCe.SampJesAandBshownhlFig.3werekeptintlleload-lockchamberfor2hotlrsarlercomPIcteremovalorlheoXjdelaycT-byadilutedHFsolution.SampleAWasheatedupto850C,sanlPleB

IVaSheatedupto)2500CandheldI-hereror mjnutes.

SampleCwasplacedinLhcUHVh,lBEchamberwithiIILOmilltlteSafterrerllOVaLoftllCOXidetaycr,lleatedlipLo

Dep(JTldeJT(Jet0/IkeCarrler/m/)I/O ()'Zi/LLI)priPLlF'7/l'ol/ Llt)7

(C

5/i)NOlly1

NUNO3tJFjl