Izindaba - Ukwakheka nokukhula kobuchwepheshe be-silicon carbide (Ⅱ)

Okwesine, indlela yokudlulisa umhwamuko ophathekayo

Iezokuthutha ngomhwamuko obonakalayo (PVT)indlela yavela kubuchwepheshe be-sublimation yesigaba somhwamuko eyasungulwa ngu-Lely ngo-1955. I-SiC powder ifakwa epayipini le-graphite futhi ishiselwe ekushiseni okuphezulu ukuze ibole futhi i-sublimate i-SiC powder, bese ishubhu le-graphite selipholile. Ngemuva kokubola kwe-SiC powder, izingxenye zesigaba somhwamuko zifakwa futhi zifakwe amakristalu e-SiC ezungeze ishubhu legraphite. Nakuba le ndlela yenza kube nzima ukuthola amakristalu angama-SiC angamasayizi amakhulu, futhi inqubo yokubeka ku-graphite tube inzima ukuyilawula, inikeza imibono kubacwaningi abalandelayo.
U-Ym Terairov et al. eRussia yethula umqondo wamakristalu embewu ngalesi sisekelo futhi yaxazulula inkinga yesimo sekristalu esingalawuleki kanye nesikhundla se-nucleation yamakristalu e-SiC. Abacwaningi abalandelayo baqhubeka bethuthuka futhi ekugcineni bathuthukisa indlela ye-physical gas phase transport (PVT) ekusetshenzisweni kwezimboni namuhla.

Njengendlela yokuqala yokukhula kwekristalu ye-SiC, indlela yokudlulisa umhwamuko obonakalayo iyindlela yokukhula evamile yokukhula kwekristalu ye-SiC. Uma kuqhathaniswa nezinye izindlela, le ndlela inezidingo eziphansi zemishini yokukhula, inqubo yokukhula elula, ukulawuleka okuqinile, ukuthuthukiswa okuphelele, kanye nocwaningo, futhi iye yaqaphela ukusetshenziswa kwezimboni. Ukwakheka kwekristalu ekhuliswe yindlela yamanje ye-PVT evamile kuboniswa esithombeni.

Izinkambu zokushisa ze-axial ne-radial zingalawulwa ngokulawula izimo zangaphandle zokushisa ezishisayo ze-graphite crucible. I-SiC powder ibekwe ngaphansi kwe-graphite crucible enezinga lokushisa eliphakeme, futhi i-crystal yembewu ye-SiC igxilwe phezulu kwe-graphite crucible ekushiseni okuphansi. Ibanga phakathi kwempushana nembewu ngokuvamile lilawulwa libe amashumi amamilimitha ukugwema ukuthintana phakathi kwekristalu eyodwa ekhulayo kanye nempushana. I-gradient yezinga lokushisa ivamise ukuba ku-15-35℃/cm. Igesi engasebenzi engu-50-5000 Pa igcinwa esithandweni ukuze kwandiswe i-convection. Ngale ndlela, ngemva kokuba i-SiC powder ishisiselwe ku-2000-2500 ℃ ngokufudumeza kwe-induction, i-SiC powder izokwehla futhi ibole ibe yi-Si, Si2C, SiC2 nezinye izingxenye zomhwamuko, futhi ithuthelwe ekugcineni kwembewu nge-convection yegesi, futhi Ikristalu ye-SiC icwebezelwe ku-crystal yembewu ukuze ifinyelele ukukhula kwekristalu eyodwa. Izinga layo lokukhula elijwayelekile lingu-0.1-2mm/h.

Inqubo ye-PVT igxile ekulawuleni izinga lokushisa lokukhula, izinga lokushisa, i-gradient, indawo yokukhula, isikhala sendawo yezinto ezibonakalayo, nokucindezela kokukhula, inzuzo yayo ukuthi inqubo yayo isivuthiwe, izinto zokusetshenziswa kulula ukukhiqiza, izindleko ziphansi, kodwa inqubo yokukhula. indlela ye-PVT inzima ukuyibona, izinga lokukhula kwekristalu lika-0.2-0.4mm/h, kunzima ukukhulisa amakristalu anogqinsi olukhulu (> 50mm). Ngemuva kwamashumi eminyaka yemizamo eqhubekayo, imakethe yamanje yama-wafers e-SiC substrate akhule ngendlela ye-PVT ibe yinkulu kakhulu, futhi ukukhishwa konyaka kwama-wafers we-SiC substrate kungafinyelela amakhulu ezinkulungwane zamawafa, futhi usayizi wawo uyashintsha kancane kancane usuka kuma-intshi angu-4 ukuya ku-6. amasentimitha angu-8, futhi ithuthukise amasampula e-SiC substrate angama-intshi angu-8.

Okwesihlanu, Indlela yokubeka umhwamuko wamakhemikhali osezingeni eliphezulu

I-High-Temperature Chemical Vapor Deposition (HTCVD) iyindlela ethuthukisiwe esekelwe ku-Chemical Vapor Deposition (CVD). Indlela yaqala ukuphakanyiswa ngo-1995 nguKordina et al., Inyuvesi yaseLinkoping, eSweden.
Umdwebo wesakhiwo sokukhula uboniswa emfanekisweni:

Lapho i-crystal ye-SiC ikhuliswa ngendlela yesigaba se-liquid, izinga lokushisa nokusabalalisa kwe-convection ngaphakathi kwesisombululo esiwusizo kuboniswa esithombeni:

Kungabonakala ukuthi izinga lokushisa eliseduze nodonga lwe-crucible kwisisombululo esisizayo liphakeme, kuyilapho izinga lokushisa ku-crystal imbewu liphansi. Phakathi nenqubo yokukhula, i-graphite crucible inikeza umthombo we-C wokukhula kwekristalu. Ngenxa yokuthi izinga lokushisa odongeni lwe-crucible liphezulu, ukuncibilika kwe-C kukhulu, futhi izinga lokuqedwa liyashesha, inani elikhulu le-C lizohlakazwa odongeni lwe-crucible ukwenza isisombululo esigcwele se-C. Lezi zixazululo ngenani elikhulu ka-C encibilikisiwe izothuthelwa engxenyeni engezansi yamakristalu embewu nge-convection ngaphakathi kwesisombululo esisizayo. Ngenxa yokushisa okuphansi kokuphela kwekristalu yembewu, ukuncibilika kwe-C ehambisanayo kunciphisa ngokuhambisanayo, futhi isisombululo sokuqala se-C-saturated siba isisombululo esiphezulu se-C ngemuva kokudluliselwa ekupheleni kokushisa okuphansi ngaphansi kwalesi simo. I-Supersaturated C esixazululweni esihlanganiswe no-Si esixazululweni esisizayo ingakhulisa i-SiC crystal epitaxial kukristalu lwembewu. Lapho ingxenye enembobo ka-C iphuma, isixazululo sibuyela ekugcineni kwezinga lokushisa eliphezulu lodonga oluyi-crucible nge-convection futhi luhlakaza u-C futhi ukuze kwakhe isixazululo esigcwele.

Yonke inqubo iphinda, futhi i-crystal ye-SiC iyakhula. Enqubweni yokukhula kwesigaba soketshezi, ukuhlakazeka kanye nemvula ka-C esixazululweni kuyinkomba ebaluleke kakhulu yenqubekelaphambili yokukhula. Ukuze kuqinisekiswe ukukhula kwekristalu okuzinzile, kuyadingeka ukugcina ibhalansi phakathi kokuqedwa kwe-C odongeni lwe-crucible kanye nemvula ekugcineni kwembewu. Uma ukuhlakazeka kwe-C kukhulu kunemvula ka-C, khona-ke i-C ku-crystal iyathuthukiswa kancane kancane, futhi i-nucleation ezenzakalelayo ye-SiC izokwenzeka. Uma ukuhlakazeka kwe-C kungaphansi kwezulu lika-C, ukukhula kwekristalu kuzoba nzima ukukufeza ngenxa yokuntuleka kwe-solute.
Ngesikhathi esifanayo, ukuthuthwa kwe-C nge-convection nakho kuthinta ukunikezwa kwe-C ngesikhathi sokukhula. Ukuze kukhule amakristalu e-SiC anekhwalithi enhle yekristalu nokuqina okwanele, kuyadingeka ukuqinisekisa ibhalansi yezinto ezintathu ezingenhla, okwandisa kakhulu ubunzima bokukhula kwesigaba se-SiC liquid. Kodwa-ke, ngokuthuthukiswa kancane kancane kanye nokuthuthukiswa kwemibono nobuchwepheshe obuhlobene, izinzuzo zokukhula kwesigaba se-liquid zamakristalu e-SiC zizobonakala kancane kancane.
Njengamanje, ukukhula kwesigaba soketshezi samakristalu angu-2-intshi we-SiC kungafinyelelwa eJapane, futhi ukukhula kwesigaba soketshezi samakristalu angama-intshi angu-4 nakho kuyathuthukiswa. Njengamanje, ucwaningo lwasekhaya olufanele alukayiboni imiphumela emihle, futhi kuyadingeka ukuthi kulandelelwe umsebenzi ofanele wocwaningo.

Okwesikhombisa, Izakhiwo ezingokomzimba namakhemikhali zamakristalu e-SiC

(1) Izakhiwo zikamshini: Amakristalu e-SiC anobulukhuni obuphakeme kakhulu kanye nokumelana nokugqokwa okuhle. Ukuqina kwayo kwe-Mohs kuphakathi kuka-9.2 no-9.3, futhi ubulukhuni bayo be-Krit buphakathi kuka-2900 no-3100Kg/mm2, okungokwesibili kuphela kumakristalu edayimane phakathi kwezinto ezitholakele. Ngenxa yezakhiwo ezinhle kakhulu zemishini ye-SiC, i-powder SiC ivame ukusetshenziswa embonini yokusika noma yokugaya, ngesidingo sonyaka esingafika ezigidini zamathani. I-coating engagugi kwezinye izinto zokusebenza izophinde isebenzise i-SiC coating, isibonelo, i-coating engagugi kweminye imikhumbi yempi yakhiwe nge-SiC coating.

(2) Izici ezishisayo: I-thermal conductivity ye-SiC ingafinyelela ku-3-5 W/cm·K, okuphindwe izikhathi ezingu-3 kune-semiconductor yendabuko engu-Si kanye nezikhathi ezingu-8 kune-GaAs. Ukukhiqizwa kokushisa kwedivayisi okulungiselelwe yi-SiC kungenziwa ngokushesha, ngakho-ke izidingo zezimo zokushisa zokushisa zedivayisi ye-SiC zikhululekile, futhi zifaneleka kakhulu ukulungiswa kwamadivayisi anamandla aphezulu. I-SiC inezinto ezizinzile ze-thermodynamic. Ngaphansi kwezimo zengcindezi evamile, i-SiC izoboliswa ngokuqondile ibe umhwamuko oqukethe u-Si no-C phezulu.

(3) Izakhiwo zamakhemikhali: I-SiC inezinto zamakhemikhali ezizinzile, ukumelana nokugqwala okuhle, futhi ayisabelani nanoma iyiphi i-asidi eyaziwayo ekamelweni lokushisa. I-SiC ebekwe emoyeni isikhathi eside izokwakha kancane ungqimba oluncane lwe-SiO2 eminyene, ivimbele ukusabela okwengeziwe kwe-oxidation. Lapho izinga lokushisa likhuphuka lifinyelela ngaphezu kuka-1700 ℃, ungqimba oluncane lwe-SiO2 luyancibilika futhi lukhiphe oksijini ngokushesha. I-SiC ingabhekana nokusabela kwe-oxidation kancane ngama-oxidants noma izisekelo ezincibilikisiwe, futhi amawafa e-SiC ngokuvamile agqwalile ku-KOH encibilikisiwe kanye ne-Na2O2 ukuze abonise ukugudluka kumakristalu e-SiC.

(4) Izakhiwo zikagesi: I-SiC njengento emele i-bandgap semiconductors ebanzi, ububanzi be-bandgap engu-6H-SiC, kanye ne-4H-SiC bungu-3.0 eV kanye no-3.2 eV ngokulandelanayo, okuyizikhathi ezi-3 kune-Si kanye nezikhathi ezingu-2 kune-GaAs. Amadivaysi e-semiconductor enziwe nge-SiC anemisinga yokuvuza emincane kanye nezinkambu zikagesi eziwohlokayo ezinkulu, ngakho-ke i-SiC ithathwa njengento efanelekile yamadivayisi anamandla amakhulu. Ukuhamba kwe-electron egcwele kwe-SiC nakho kuphakeme ngokuphindwe izikhathi ezi-2 kunaleyo ye-Si, futhi kunezinzuzo ezisobala ekulungiseleleni amadivaysi asebenzisa imvamisa ephezulu. Amakristalu ohlobo lwe-P-SiC noma amakristalu e-SiC ohlobo lwe-N angatholwa ngokufaka ama-athomu okungcola kumakristalu. Njengamanje, amakristalu e-SiC ohlobo lwe-P asetshenziswa kakhulu yi-Al, B, Be, O, Ga, Sc, namanye ama-athomu, kanti amakristalu ohlobo lwe-N agqitshwa kakhulu ama-athomu angu-N. Umehluko ekugxilweni kwe-doping kanye nohlobo kuzoba nomthelela omkhulu ezintweni ezibonakalayo namakhemikhali e-SiC. Ngasikhathi sinye, isithwali samahhala singabethelwa nge-doping yezinga elijulile njenge-V, ukumelana kungandiswa, futhi i-crystal ye-SiC ye-semi-insulating ingatholakala.

(5) Izakhiwo zokubuka: Ngenxa yegebe lebhendi elibanzi ngokuqhathaniswa, ikristalu ye-SiC evuliwe ayinambala futhi isobala. Amakristalu e-SiC ane-doped abonisa imibala ehlukene ngenxa yezakhiwo zabo ezihlukene, isibonelo, i-6H-SiC iluhlaza ngemva kwe-doping N; I-4H-SiC insundu. I-15R-SiC iphuzi. Ifakwe nge-Al, i-4H-SiC ibonakala iluhlaza okwesibhakabhaka. Kuyindlela enembile yokuhlukanisa uhlobo lwekristalu ye-SiC ngokubheka umehluko wombala. Ngocwaningo oluqhubekayo emikhakheni ehlobene ne-SiC eminyakeni engama-20 edlule, impumelelo enkulu yenziwe kubuchwepheshe obuhlobene.

Okwesishiyagalombili, Ukwethulwa kwesimo sokuthuthukiswa kwe-SiC

Njengamanje, imboni ye-SiC isivele iphelele, kusukela kuma-wafers angaphansi,futhii-epitaxializinkwa eziwucwecweekukhiqizweni kwedivayisi, nokupakishwa, lonke uchungechunge lwezimboni selikhulile, futhi linganikezela ngemikhiqizo ehlobene ne-SiC emakethe.

UCree ungumholi embonini yokukhula kwekristalu ye-SiC enesikhundla esiphambili kukho kokubili usayizi nekhwalithi yamawafa e-SiC substrate. I-Cree njengamanje ikhiqiza ama-chips e-SiC substrate angama-300,000 ngonyaka, ebalwa ngaphezu kuka-80% wokuthunyelwa komhlaba wonke.

NgoSepthemba 2019, iCree yamemezela ukuthi izokwakha isikhungo esisha eNew York State, e-USA, esizosebenzisa ubuchwepheshe obuphambili kakhulu ukukhulisa amandla obubanzi obungama-200 mm kanye nama-wafers angaphansi kwe-RF SiC, okubonisa ukuthi ubuchwepheshe bayo bokulungiselela izinto ezingaphansi kwe-200 mm SiC bakhule ngokwengeziwe.

Njengamanje, imikhiqizo evamile yama-chips e-SiC substrate emakethe ikakhulukazi i-4H-SiC kanye ne-6H-SiC izinhlobo eziqhutshwayo kanye nezinhlobo ezifakwe ngaphakathi kwama-intshi angu-2-6.
Ngo-Okthoba 2015, uCree waba ngowokuqala ukwethula amawafa angama-200 mm SiC substrate ohlobo lwe-N ne-LED, okuphawula ukuqala kwamawafa angama-SiC angama-8-inch emakethe.
Ngo-2016, uRomm waqala ukuxhasa iqembu le-Venturi futhi waba ngowokuqala ukusebenzisa inhlanganisela ye-IGBT + SiC SBD emotweni ukuze athathe indawo ye-IGBT + Si FRD inverter yendabuko engu-200 kW. Ngemuva kokuthuthukiswa, isisindo se-inverter sincishiswa ngo-2 kg futhi ubukhulu buncishiswa ngo-19% ngenkathi kugcinwa amandla afanayo.

Ngo-2017, ngemva kokutholwa okuqhubekayo kwe-SiC MOS + SiC SBD, isisindo asinciphisi ngo-6 kg kuphela, kodwa ubukhulu buncishiswe ngo-43%, futhi amandla okuguqula aphinde akhuphuke kusuka ku-200 kW kuya ku-220 kW.
Ngemuva kokuthi uTesla emukele amadivaysi asekelwe ku-SIC kuma-inverter ayinhloko emikhiqizo yakhe ye-Model 3 ngo-2018, umphumela wokubonisa wandiswa ngokushesha, okwenza imakethe yezimoto ye-xEV yaba umthombo wenjabulo emakethe ye-SiC. Ngokusetshenziswa ngempumelelo kwe-SiC, inani layo lemakethe elihlobene nalo liye lenyuka ngokushesha.

Okwesishiyagalolunye, Isiphetho:

Ngokuthuthuka okuqhubekayo kobuchwepheshe bemboni obuhlobene ne-SiC, isivuno nokuthembeka kwayo kuzothuthukiswa ngokwengeziwe, intengo yemishini ye-SiC nayo izokwehliswa, futhi nokuncintisana kwemakethe kwe-SiC kuzoba sobala kakhulu. Ngokuzayo, amadivaysi e-SiC azosetshenziswa kabanzi emikhakheni ehlukahlukene efana nezimoto, ezokuxhumana, amagridi kagesi, nezokuthutha, futhi imakethe yomkhiqizo izoba banzi, nosayizi wemakethe uzonwetshwa ngokwengeziwe, ube usekelo olubalulekile kuzwelonke. umnotho.