I-CVD silicon carbide coating-2

I-CVD silicon carbide coating

1. Kungani kukhona ai-silicon carbide coating

Ungqimba lwe-epitaxial ifilimu ethize ethile encane eyikristalu ekhule ngesisekelo se-wafer ngenqubo ye-epitaxial. I-wafer ye-substrate kanye nefilimu encane ye-epitaxial ngokuhlangene ibizwa ngokuthi ama-epitaxial wafers. Phakathi kwabo, iI-silicon carbide epitaxialungqimba ukhuliswa ku-conductive silicon carbide substrate ukuze kutholwe i-silicon carbide homogeneous epitaxial wafer, engenziwa futhi ibe yimishini yamandla njenge-Schottky diode, ama-MOSFET, nama-IGBT. Phakathi kwazo, esetshenziswa kakhulu yi-4H-SiC substrate.

Njengoba wonke amadivaysi enziwa ngokuyisisekelo ku-epitaxy, ikhwalithi yei-epitaxyinomthelela omkhulu ekusebenzeni kwedivayisi, kodwa ikhwalithi ye-epitaxy ithintwa ukucubungula amakristalu nama-substrates. Iphakathi nendawo embonini futhi idlala indima ebaluleke kakhulu ekuthuthukisweni kwemboni.

Izindlela eziyinhloko zokulungiselela izingqimba ze-silicon carbide epitaxial yilezi: indlela yokukhula kwe-evaporation; i-liquid phase epitaxy (LPE); i-molecular beam epitaxy (MBE); I-chemical vapor deposition (CVD).

Phakathi kwazo, i-chemical vapor deposition (CVD) iyindlela ethandwa kakhulu ye-4H-SiC homoepitaxial. I-4-H-SiC-CVD epitaxy ngokuvamile isebenzisa imishini ye-CVD, engaqinisekisa ukuqhubeka kwe-epitaxial layer 4H crystal SiC ngaphansi kwezimo zokushisa eziphakeme zokukhula.

Emishinini ye-CVD, i-substrate ayikwazi ukubekwa ngokuqondile ensimbi noma ivele ibekwe phezu kwesisekelo se-epitaxial deposition, ngoba ihlanganisa izici ezihlukahlukene ezifana nesiqondiso sokugeleza kwegesi (evundlile, mpo), izinga lokushisa, ingcindezi, ukulungiswa, nokungcola okuwayo. Ngakho-ke, isisekelo siyadingeka, bese i-substrate ibekwe kudiski, bese i-epitaxial deposition yenziwa ku-substrate kusetshenziswa ubuchwepheshe be-CVD. Lesi sisekelo siyisisekelo se-graphite esihlanganiswe ne-SiC.

Njengengxenye ewumgogodla, isisekelo segraphite sinezici zamandla athile aphezulu kanye ne-modulus ethize, ukumelana nokushaqeka okuhle kokushisa nokumelana nokugqwala, kodwa ngesikhathi senqubo yokukhiqiza, i-graphite izogqwala futhi ibe yimpuphu ngenxa yensalela yamagesi agqwalayo kanye ne-organic metal. udaba, futhi impilo yesevisi yesisekelo segraphite izoncishiswa kakhulu.

Ngesikhathi esifanayo, i-graphite powder ewile izongcolisa i-chip. Enqubweni yokukhiqiza ama-silicon carbide epitaxial wafers, kunzima ukuhlangabezana nezidingo zabantu eziqinile zokusetshenziswa kwezinto ze-graphite, ezikhawulela kakhulu ukuthuthukiswa nokusebenza kwayo okungokoqobo. Ngakho-ke, ubuchwepheshe bokugqoka baqala ukuphakama.

2. Izinzuzo zeUkufakwa kwe-SiC

Izakhiwo ezingokwenyama nezamakhemikhali zokugqoka zinezidingo eziqinile zokumelana nokushisa okuphezulu nokumelana nokugqwala, okuthinta ngokuqondile isivuno nokuphila komkhiqizo. Izinto ze-SiC zinamandla aphezulu, ubulukhuni obuphezulu, i-coefficient ephansi yokwandisa okushisayo kanye nokuhamba kahle kwe-thermal. Kuyinto ebalulekile yesakhiwo esisezingeni eliphezulu lokushisa kanye nokokusebenza kwe-semiconductor yezinga lokushisa eliphezulu. Isetshenziselwa isisekelo se-graphite. Izinzuzo zayo yilezi:

-I-SiC ayizwani nokugqwala futhi ingasonga ngokugcwele isisekelo segraphite, futhi inokuminyana okuhle ukuze igweme ukulimala ngenxa yegesi edlayo.

-I-SiC ine-conductivity ephezulu ye-thermal kanye namandla aphezulu okubopha ngesisekelo se-graphite, ukuqinisekisa ukuthi ukugqoka akulula ukuwa ngemva kwemijikelezo eminingi yokushisa ephezulu kanye ne-low-temperature.

-I-SiC inokuqina okuhle kwamakhemikhali ukuvimbela ukumboza ekuhlulekeni endaweni yokushisa ephezulu kanye neyonakele.

Ngaphezu kwalokho, ama-epitaxial furnaces ezinto ezahlukene adinga amathreyi e-graphite anezinkomba ezihlukile zokusebenza. Ukumataniswa kwe-coefficient yokwandisa okushisayo kwezinto ze-graphite kudinga ukuzivumelanisa nezinga lokushisa lokukhula kwesithando somlilo se-epitaxial. Isibonelo, izinga lokushisa lokukhula kwe-silicon carbide epitaxial liphezulu, futhi ithreyi eline-coefficient ephezulu yokwandisa okushisayo iyadingeka. I-coefficient yokwandisa okushisayo ye-SiC isondelene kakhulu ne-graphite, okwenza ifaneleke njengento ekhethwayo yokumbozwa kwendawo yesisekelo segraphite.
Izinto ze-SiC zinezinhlobonhlobo zamafomu e-crystal, futhi ezivame kakhulu yi-3C, 4H ne-6H. Izinhlobo ezahlukene zekristalu ze-SiC zinokusetshenziswa okuhlukile. Isibonelo, i-4H-SiC ingasetshenziswa ukwenza amadivaysi anamandla amakhulu; I-6H-SiC iyisimeme kakhulu futhi ingasetshenziswa ukwenza amadivaysi e-optoelectronic; I-3C-SiC ingasetshenziselwa ukukhiqiza izendlalelo ze-GaN epitaxial futhi yenze amadivayisi e-SiC-GaN RF ngenxa yesakhiwo sayo esifanayo ne-GaN. I-3C-SiC nayo ijwayele ukubizwa ngokuthi i-β-SiC. Ukusetshenziswa okubalulekile kwe-β-SiC kufana nefilimu elincanyana kanye nezinto zokumboza. Ngakho-ke, i-β-SiC okwamanje iyimpahla eyinhloko yokugqoka.
Izingubo ze-SiC zivame ukusetshenziswa ekukhiqizeni i-semiconductor. Asetshenziswa kakhulu kuma-substrates, epitaxy, oxidation diffusion, etching kanye nokufakwa kwe-ion. Izakhiwo ezingokwenyama namakhemikhali zokugqoka zinezidingo eziqinile ekuphikeleni izinga lokushisa eliphezulu nokumelana nokugqwala, okuthinta ngokuqondile isivuno nokuphila komkhiqizo. Ngakho-ke, ukulungiswa kwe-SiC coating kubalulekile.