Tsarin da fasaha na haɓaka na silicon carbide (Ⅱ)

Na hudu, Hanyar canja wurin tururin jiki

Hanyar jigilar tururi ta jiki (PVT) ta samo asali ne daga fasaha na zamani na sublimation na tururi wanda Lely ya kirkiro a cikin 1955. Ana sanya foda na SiC a cikin bututu mai graphite kuma mai tsanani zuwa babban zafin jiki don lalata da kuma lalata SiC foda, sa'an nan kuma an sanyaya tube graphite. Bayan bazuwar foda na SiC, ana ajiye kayan aikin tururi kuma an sanya su cikin lu'ulu'u na SiC a kusa da bututun graphite. Ko da yake wannan hanya yana da wuya a sami babban girman SiC guda lu'ulu'u, kuma tsarin ƙaddamarwa a cikin bututun graphite yana da wuyar sarrafawa, yana ba da ra'ayoyi ga masu bincike na gaba.
Ym Terairov et al. a Rasha ya gabatar da ra'ayi na lu'ulu'u iri a kan wannan tushe, kuma ya warware matsalar siffar crystal marar sarrafawa da matsayi na tsakiya na SiC crystals. Masu bincike na gaba sun ci gaba da haɓaka kuma a ƙarshe sun haɓaka hanyar jigilar iskar gas ta zahiri (PVT) a cikin amfani da masana'antu a yau.

A matsayin farkon hanyar ci gaban kristal na SiC, hanyar canja wurin tururi ta zahiri ita ce hanya mafi girma ta girma don ci gaban SiC crystal. Idan aka kwatanta da sauran hanyoyin, hanyar tana da ƙananan buƙatu don kayan haɓaka haɓaka, tsarin haɓaka mai sauƙi, mai ƙarfi mai ƙarfi, ci gaba mai zurfi da bincike, kuma ya gane aikace-aikacen masana'antu. An nuna tsarin kristal da aka girma ta hanyar PVT na yau da kullun a cikin adadi.

Za a iya sarrafa filayen zafin jiki na axial da radial ta hanyar sarrafa yanayin insulation na zafi na waje na graphite crucible. Ana sanya foda na SiC a kasan ginshiƙan graphite tare da zafin jiki mafi girma, kuma ana gyara ƙwayar ƙwayar SiC a saman faifan graphite tare da ƙananan zafin jiki. Nisa tsakanin foda da iri gabaɗaya ana sarrafa su ya zama dubun milimita don gujewa hulɗa tsakanin kristal mai girma da foda. Matsakaicin zafin jiki yawanci yana cikin kewayon 15-35 ℃ / cm. Ana ajiye iskar gas na 50-5000 Pa a cikin tanderun don ƙara haɓakawa. Ta wannan hanya, bayan da SiC foda aka mai tsanani zuwa 2000-2500 ℃ ta shigar dumama, da SiC foda zai sublimate da bazuwa cikin Si, Si2C, SiC2 da sauran tururi aka gyara, kuma za a kai shi zuwa karshen iri tare da gas convection, da kuma SiC crystal an yi crystallized akan kristal iri don cimma ci gaban kristal guda ɗaya. Matsakaicin girman girmansa shine 0.1-2mm/h.

Tsarin PVT yana mayar da hankali kan kula da zafin jiki na girma, yanayin zafin jiki, yanayin girma, sararin samaniya da matsa lamba, amfaninsa shine tsarinsa yana da girma, albarkatun kasa suna da sauƙi don samarwa, farashin yana da ƙasa, amma tsarin ci gaba na girma. Hanyar PVT yana da wuyar kiyayewa, ƙimar girma na crystal na 0.2-0.4mm / h, yana da wuya a girma lu'ulu'u tare da babban kauri (> 50mm). Bayan shekaru da yawa na ci gaba da ƙoƙarin, kasuwa na yanzu na SiC substrate wafers da aka girma ta hanyar PVT ya kasance mai girma sosai, kuma yawan fitowar wafers na SiC na shekara-shekara na iya kaiwa ɗaruruwan dubban wafers, kuma girmansa yana canzawa a hankali daga inci 4 zuwa inci 6. , kuma ya haɓaka inci 8 na samfuran substrate na SiC.

 

Na biyar,Hanyar saka tururi mai zafi mai zafi

 

Babban Zazzabi Chemical Vapor Deposition (HTCVD) ingantacciyar hanya ce da ta dogara akan Jigon Turin Sinadarai (CVD). An fara gabatar da hanyar a cikin 1995 ta Kordina et al., Jami'ar Linkoping, Sweden.
An nuna hoton tsarin girma a cikin adadi:

Za a iya sarrafa filayen zafin jiki na axial da radial ta hanyar sarrafa yanayin insulation na zafi na waje na graphite crucible. Ana sanya foda na SiC a kasan ginshiƙan graphite tare da zafin jiki mafi girma, kuma ana gyara ƙwayar ƙwayar SiC a saman faifan graphite tare da ƙananan zafin jiki. Nisa tsakanin foda da iri gabaɗaya ana sarrafa su ya zama dubun milimita don gujewa hulɗa tsakanin kristal mai girma da foda. Matsakaicin zafin jiki yawanci yana cikin kewayon 15-35 ℃ / cm. Ana ajiye iskar gas na 50-5000 Pa a cikin tanderun don ƙara haɓakawa. Ta wannan hanya, bayan da SiC foda aka mai tsanani zuwa 2000-2500 ℃ ta shigar dumama, da SiC foda zai sublimate da bazuwa cikin Si, Si2C, SiC2 da sauran tururi aka gyara, kuma za a kai shi zuwa karshen iri tare da gas convection, da kuma SiC crystal an yi crystallized akan kristal iri don cimma ci gaban kristal guda ɗaya. Matsakaicin girman girmansa shine 0.1-2mm/h.

Tsarin PVT yana mayar da hankali kan kula da zafin jiki na girma, yanayin zafin jiki, yanayin girma, sararin samaniya da matsa lamba, amfaninsa shine tsarinsa yana da girma, albarkatun kasa suna da sauƙi don samarwa, farashin yana da ƙasa, amma tsarin ci gaba na girma. Hanyar PVT yana da wuyar kiyayewa, ƙimar girma na crystal na 0.2-0.4mm / h, yana da wuya a girma lu'ulu'u tare da babban kauri (> 50mm). Bayan shekaru da yawa na ci gaba da ƙoƙarin, kasuwa na yanzu na SiC substrate wafers da aka girma ta hanyar PVT ya kasance mai girma sosai, kuma yawan fitowar wafers na SiC na shekara-shekara na iya kaiwa ɗaruruwan dubban wafers, kuma girmansa yana canzawa a hankali daga inci 4 zuwa inci 6. , kuma ya haɓaka inci 8 na samfuran substrate na SiC.

 

Na biyar,Hanyar saka tururi mai zafi mai zafi

 

Babban Zazzabi Chemical Vapor Deposition (HTCVD) ingantacciyar hanya ce da ta dogara akan Jigon Turin Sinadarai (CVD). An fara gabatar da hanyar a cikin 1995 ta Kordina et al., Jami'ar Linkoping, Sweden.
An nuna hoton tsarin girma a cikin adadi:

Lokacin da SiC crystal ya girma ta hanyar ruwa lokaci, ana nuna zafin jiki da rarrabawar convection a cikin bayani na taimako a cikin adadi:

Ana iya ganin cewa zafin jiki a kusa da bangon crucible a cikin bayani na taimako ya fi girma, yayin da yawan zafin jiki a cikin nau'in crystal yana da ƙasa. A lokacin tsarin girma, graphite crucible yana samar da tushen C don haɓakar crystal. Saboda yawan zafin jiki a bangon crucible yana da girma, daɗaɗɗen C yana da girma, kuma yawan rushewar yana da sauri, babban adadin C za a narkar da shi a bangon bango don samar da cikakken bayani na C. Wadannan mafita tare da adadi mai yawa. na C narkar da za a jigilar zuwa ƙananan ɓangaren lu'ulu'u na iri ta hanyar juzu'i a cikin maganin taimako. Saboda ƙananan zafin jiki na ƙarshen kristal iri, solubility na daidaitaccen C yana raguwa daidai, kuma ainihin C-cikakken bayani ya zama cikakkiyar bayani na C bayan an canza shi zuwa ƙarshen ƙananan zafin jiki a ƙarƙashin wannan yanayin. Suprataturated C a cikin bayani haɗe da Si a cikin ƙarin bayani na iya girma SiC crystal epitaxial akan kristal iri. Lokacin da babban ɓangaren C ya fito waje, maganin zai dawo zuwa ƙarshen zafin bangon bango tare da convection, kuma ya sake narkar da C don samar da cikakken bayani.

Dukan tsari yana maimaitawa, kuma kristal SiC yana girma. A cikin tsarin girma lokaci na ruwa, rushewa da hazo na C a cikin bayani shine mahimmancin mahimmancin ci gaban ci gaba. Don tabbatar da ingantaccen ci gaban kristal, ya zama dole don kula da daidaituwa tsakanin rushewar C a bangon da ba a taɓa gani ba da hazo a ƙarshen iri. Idan rushewar C ya fi hazo na C, to, C a cikin crystal yana haɓaka a hankali, kuma ƙaddamarwar SiC ba zato ba tsammani zai faru. Idan rushewar C ya kasance ƙasa da hazo na C, haɓakar kristal zai yi wuya a aiwatar da shi saboda rashin solute.
A lokaci guda kuma, jigilar C ta hanyar convection shima yana shafar samar da C yayin girma. Don girma lu'ulu'u na SiC tare da kyakkyawan ingancin kristal da isasshen kauri, wajibi ne don tabbatar da ma'auni na abubuwan uku da ke sama, wanda ke ƙaruwa da wahalar ci gaban lokacin ruwa na SiC. Koyaya, tare da haɓakawa sannu a hankali da haɓaka ƙa'idodi da fasahohi masu alaƙa, fa'idodin girma lokacin ruwa na lu'ulu'u na SiC za su nuna a hankali.
A halin yanzu, ana iya samun ci gaban lokacin ruwa na lu'ulu'u na SiC 2-inch a Japan, kuma ana haɓaka haɓakar lokacin ruwa na lu'ulu'u 4-inch. A halin yanzu, binciken da ya dace a cikin gida bai sami sakamako mai kyau ba, kuma ya zama dole a bi diddigin aikin binciken da ya dace.

 

Na bakwai, Kaddarorin jiki da sunadarai na lu'ulu'u na SiC

 

(1) Kaddarorin injina: Lu'ulu'u na SiC suna da tsayin daka sosai da juriya mai kyau. Taurin Mohs ɗin sa yana tsakanin 9.2 da 9.3, kuma taurin Krit ɗin sa yana tsakanin 2900 da 3100Kg/mm2, wanda shine na biyu kawai ga lu'ulu'u na lu'u-lu'u tsakanin kayan da aka gano. Saboda kyawawan kayan aikin injiniya na SiC, ana amfani da foda SiC sau da yawa a cikin yankan ko masana'antar niƙa, tare da buƙatar shekara-shekara har zuwa miliyoyin ton. Rufin da ke jure lalacewa akan wasu kayan aikin kuma zai yi amfani da murfin SiC, alal misali, suturar da ke jure lalacewa akan wasu jiragen ruwa na yaƙi ya ƙunshi suturar SiC.

(2) Abubuwan thermal: thermal conductivity na SiC na iya kaiwa 3-5 W / cm · K, wanda shine sau 3 na semiconductor Si da sau 8 na GaAs. Ayyukan zafi na na'urar da aka shirya ta SiC za a iya yin sauri da sauri, don haka bukatun yanayin zafi na na'urar SiC ba su da sauƙi, kuma ya fi dacewa da shirye-shiryen na'urori masu ƙarfi. SiC yana da ingantaccen kaddarorin thermodynamic. A ƙarƙashin yanayin matsa lamba na al'ada, SiC za a ruɓe kai tsaye cikin tururi mai ɗauke da Si da C a sama.

(3) Abubuwan sinadarai: SiC yana da kaddarorin sinadarai tsayayye, juriya mai kyau, kuma baya amsawa da kowane sanannen acid a cikin ɗaki. SiC da aka sanya a cikin iska na dogon lokaci zai zama sannu a hankali ya samar da wani bakin ciki na SiO2 mai yawa, yana hana ƙarin halayen iskar shaka. Lokacin da zafin jiki ya tashi zuwa fiye da 1700 ℃, SiO2 bakin ciki Layer narke kuma oxidizes da sauri. SiC na iya ɗaukar jinkirin haɓakar iskar oxygen tare da narkakken oxidants ko tushe, kuma SiC wafers galibi ana lalata su a cikin narkakkar KOH da Na2O2 don nuna ɓarna a cikin lu'ulu'u na SiC.

(4) Kaddarorin lantarki: SiC a matsayin kayan wakilci na masu rarraba bandgap mai faɗi, 6H-SiC da 4H-SiC bandgap nisa sune 3.0 eV da 3.2 eV bi da bi, wanda shine sau 3 na Si da sau 2 na GaAs. Na'urorin da aka yi da na'urorin da aka yi da SiC suna da ƙaramin ɗigogi a halin yanzu da mafi girman fashewar filin lantarki, don haka ana ɗaukar SiC azaman ingantaccen abu don na'urori masu ƙarfi. Cikakkun motsin lantarki na SiC shima ya ninka na Si sau 2, kuma yana da fa'ida a bayyane a cikin shirye-shiryen na'urori masu ƙarfi. Ana iya samun lu'ulu'u na nau'in SiC ko nau'in sic na N-nau'in SiC ta hanyar doping ƙazantattun ƙwayoyin cuta a cikin lu'ulu'u. A halin yanzu, nau'in lu'ulu'u na SiC na Al, B, Be, O, Ga, Sc da sauran kwayoyin halitta, kuma N-type sic crystals ana yin su ne ta hanyar N atom. Bambance-bambancen maida hankali da nau'in doping zai yi tasiri mai girma akan kayan jiki da sinadarai na SiC. A lokaci guda, za a iya ƙusa mai ɗaukar kaya kyauta ta hanyar zurfin matakin doping kamar V, ana iya ƙara ƙarfin juriya, kuma ana iya samun kristal SiC mai rufewa.

(5) Kaddarorin gani: Saboda tazarar maɗaukaki mai faɗi, SiC crystal mara launi da bayyananne. Doped SiC lu'ulu'u suna nuna launuka daban-daban saboda bambancin kaddarorin su, alal misali, 6H-SiC kore ne bayan doping N; 4H-SiC launin ruwan kasa. 15R-SiC rawaya ne. Doped tare da Al, 4H-SiC yana bayyana shuɗi. Hanya ce mai hankali don bambance nau'in crystal na SiC ta hanyar lura da bambancin launi. Tare da ci gaba da bincike kan filayen da suka danganci SiC a cikin shekaru 20 da suka gabata, an sami babban ci gaba a cikin fasahohi masu alaƙa.

 

Na takwas,Gabatarwar matsayin ci gaban SiC

A halin yanzu, masana'antar SiC ta ƙara zama cikakke, daga wafers, wafers na epitaxial zuwa samar da na'urar, marufi, duk sarkar masana'antar ta girma, kuma tana iya ba da samfuran da suka danganci SiC ga kasuwa.

Cree jagora ne a cikin masana'antar haɓaka kristal na SiC tare da babban matsayi a duka girman da ingancin wafers na SiC. A halin yanzu Cree yana samar da kwakwalwan kwamfuta na SiC 300,000 a kowace shekara, yana lissafin sama da 80% na jigilar kayayyaki na duniya.

A watan Satumba na 2019, Cree ya ba da sanarwar cewa za ta gina wani sabon wurin aiki a jihar New York, Amurka, wanda zai yi amfani da fasaha mafi haɓaka don haɓaka ƙarfin diamita na 200 mm da RF SiC substrate wafers, yana nuna cewa fasahar shirye-shiryen kayan maye na SiC na 200 mm yana da zama mafi girma.

A halin yanzu, samfuran da aka fi sani da kwakwalwan kwamfuta na SiC akan kasuwa sune 4H-SiC da 6H-SiC masu gudanarwa da nau'ikan insulated na inci 2-6.
A cikin Oktoba 2015, Cree shine farkon wanda ya ƙaddamar da 200 mm SiC substrate wafers don nau'in N da LED, wanda ke nuna farkon 8-inch substrate wafers SiC zuwa kasuwa.
A cikin 2016, Romm ya fara ɗaukar nauyin ƙungiyar Venturi kuma shine farkon wanda yayi amfani da haɗin IGBT + SiC SBD a cikin motar don maye gurbin maganin IGBT + Si FRD a cikin inverter na 200 kW na gargajiya. Bayan haɓakawa, nauyin inverter yana raguwa da 2 kg kuma an rage girman ta 19% yayin da yake riƙe da wannan iko.

A cikin 2017, bayan ƙarin tallafi na SiC MOS + SiC SBD, ba kawai nauyin ya rage ta 6 kg ba, girman yana raguwa da 43%, kuma ƙarfin inverter kuma yana ƙaruwa daga 200 kW zuwa 220 kW.
Bayan Tesla ya karɓi na'urorin da ke tushen SIC a cikin manyan masu juyawa na samfuransa na Model 3 a cikin 2018, tasirin zanga-zangar ya haɓaka cikin sauri, yana mai da kasuwar kera motoci ta xEV nan da nan ta zama tushen farin ciki ga kasuwar SiC. Tare da nasarar aikace-aikacen SiC, ƙimar fitar da kasuwa mai alaƙa ita ma ta tashi cikin sauri.

Na tara,Ƙarshe:

Tare da ci gaba da haɓaka fasahohin masana'antu masu alaƙa da SiC, yawan amfanin sa da amincinsa za a ƙara inganta, kuma za a rage farashin na'urorin SiC, kuma ƙimar kasuwar SiC za ta kasance a bayyane. A nan gaba, za a fi amfani da na'urorin SiC a fannoni daban-daban kamar motoci, sadarwa, hanyoyin samar da wutar lantarki, da sufuri, kuma kasuwar kayayyakin za ta kasance mai fa'ida, kuma za a kara fadada girman kasuwar, ta yadda za ta zama muhimmin taimako ga kasa da kasa. tattalin arziki.