Peb txoj kev loj hlob rau SiC siv lead ua

Raws li pom nyob rau hauv daim duab 3, muaj peb lub hom phiaj tseem ceeb aiming los muab SiC ib leeg siv lead ua zoo thiab effciency: kua theem epitaxy (LPE), lub cev vapor thauj (PVT), thiab high-temperature chemical vapor deposition (HTCVD). PVT yog cov txheej txheem tsim tau zoo rau kev tsim SiC ib leeg siv lead ua, uas yog siv dav hauv cov tuam txhab loj wafer.

Txawm li cas los xij, tag nrho peb cov txheej txheem tau hloov kho sai thiab tsim kho tshiab. Nws tseem tsis tau muaj peev xwm ua kom dhau qhov txheej txheem twg yuav raug coj los siv rau yav tom ntej. Tshwj xeeb, zoo SiC ib leeg siv lead ua uas tsim los ntawm kev daws kev loj hlob ntawm tus nqi ntau tau tshaj tawm nyob rau xyoo tas los no, SiC bulk loj hlob hauv cov kua theem yuav tsum tau kub qis dua li cov txheej txheem sublimation los yog deposition, thiab nws ua tau zoo tshaj plaws hauv kev tsim P -type SiC substrates (Table 3) [33, 34].

Daim duab 3: Schematic ntawm peb yam tseem ceeb SiC ib leeg siv lead ua txoj kev loj hlob: (a) kua theem epitaxy; (b) lub cev vapor thauj; (c) high-temperature chemical vapor deposition

Table 3: Sib piv ntawm LPE, PVT thiab HTCVD rau kev loj hlob SiC ib leeg muaju [33, 34]

Kev loj hlob kev daws teeb meem yog txheej txheem thev naus laus zis rau kev npaj cov khoom siv semiconductors [36]. Txij li thaum xyoo 1960, cov kws tshawb fawb tau sim tsim cov siv lead ua hauv kev daws teeb meem [37]. Thaum cov thev naus laus zis tau tsim, lub supersaturation ntawm txoj kev loj hlob tuaj yeem tswj tau zoo, uas ua rau txoj kev daws teeb meem zoo tshaj plaws rau kev tau txais txiaj ntsig zoo ib leeg siv lead ua ingots.

Rau kev daws kev loj hlob ntawm SiC ib leeg siv lead ua, Si qhov chaw stems los ntawm cov ntshiab Si yaj thaum lub graphite crucible pab ob lub hom phiaj: rhaub thiab C solute qhov chaw. SiC ib leeg muaju muaj feem yuav loj hlob raws li qhov zoo tshaj plaws stoichiometric piv thaum qhov piv ntawm C thiab Si yog ze rau 1, qhia tias qhov tsis xws luag tsawg [28]. Txawm li cas los xij, ntawm atmospheric siab, SiC qhia tias tsis muaj melting point thiab decomposes ncaj qha los ntawm vaporization attemperatures tshaj li ntawm 2,000 ° C. SiC melts, raws li theoretical kev cia siab, tsuas yog tsim nyob rau hauv hnyav yuav pom los ntawm Si-C binary theem daim duab (Fig. 4) uas nyob rau ntawm kub gradient thiab tov system. Qhov siab dua C hauv Si yaj nws txawv ntawm 1at.% mus rau 13at.%. Kev tsav tsheb C supersaturation, qhov kev loj hlob sai dua, thaum qis C quab yuam ntawm kev loj hlob yog C supersaturation uas yog dominated siab ntawm 109 Pa thiab kub siab tshaj 3,200 ° C. Nws muaj peev xwm supersaturation ua ib tug du nto [22, 36-38].temperatures ntawm 1,400 thiab 2,800 ° C, solubility ntawm C nyob rau hauv lub Si yaj nws txawv ntawm 1at.% mus rau 13at.%. Lub zog tsav ntawm kev loj hlob yog C supersaturation uas yog dominated los ntawm kub gradient thiab kev daws teeb meem. Qhov siab dua qhov C supersaturation, qhov kev loj hlob sai dua, thaum qis C supersaturation ua rau lub ntsej muag du [22, 36-38].

Daim duab 4: Si-C binary theem daim duab [40]

Doping hloov pauv hlau cov ntsiab lus lossis cov ntsiab lus tsis tshua muaj hauv ntiaj teb tsis tsuas yog txo qhov kev loj hlob ntawm qhov kub thiab txias tab sis zoo li yog tib txoj hauv kev los txhim kho carbon solubility hauv Si yaj. Qhov sib ntxiv ntawm kev hloov pauv pawg hlau, xws li Ti [8, 14-16, 19, 40-52], Cr [29, 30, 43, 50, 53-75], Co [63, 76], Fe [77- 80], thiab lwm yam. lossis cov hlau tsis tshua muaj hauv ntiaj teb, xws li Ce [81], Y [82], Sc, thiab lwm yam rau Si yaj tso cai rau cov pa roj carbon. solubility kom tshaj 50at.% nyob rau hauv ib lub xeev ze rau thermodynamic equilibrium. Ntxiv mus, cov txheej txheem LPE yog qhov zoo rau P-hom doping ntawm SiC, uas tuaj yeem ua tiav los ntawm alloying Al rau hauv
hnyav [50, 53, 56, 59, 64, 71-73, 82, 83]. Txawm li cas los xij, kev koom ua ke ntawm Al ua rau muaj kev nce ntxiv ntawm P-hom SiC ib leeg muaju [49, 56].Apart from N-hom kev loj hlob nyob rau hauv nitrogen doping,

txoj kev loj hlob feem ntau tshwm sim nyob rau hauv ib qho inert gas cua. Txawm hais tias helium (Nws) yog kim dua li argon, nws tau txais txiaj ntsig los ntawm ntau tus kws tshawb fawb vim nws qhov qis qis thiab siab dua thermal conductivity (8 npaug ntawm argon) [85]. Qhov kev tsiv teb tsaws chaw thiab Cr cov ntsiab lus hauv 4H-SiC zoo ib yam nyob rau hauv Nws thiab Ar huab cua, nws tau ua pov thawj tias kev loj hlob nyob rau hauv Heresults nyob rau hauv ib qho kev loj hlob ntau dua li kev loj hlob nyob rau hauv Ar vim yog lub tshav kub dissipation ntawm cov noob [68]. Nws impedes lub voids tsim nyob rau hauv lub zus siv lead ua thiab spontaneous nucleation nyob rau hauv cov tshuaj, ces, ib tug du nto morphology yuav tau txais [86].

Daim ntawv no qhia txog kev txhim kho, kev siv, thiab cov khoom siv ntawm SiC, thiab peb txoj hauv kev loj hlob SiC ib leeg siv lead ua. Hauv ntu nram qab no, cov kev daws teeb meem loj hlob tam sim no thiab cov ntsiab lus tseem ceeb raug tshuaj xyuas. Thaum kawg, qhov kev pom zoo tau npaj los tham txog cov teeb meem thiab kev ua haujlwm yav tom ntej txog kev loj hlob ntawm SiC ib leeg siv lead ua los ntawm txoj kev daws teeb meem.