CVD SiC Txheej yog dab tsi?
Chemical vapor deposition (CVD) yog cov txheej txheem nqus tsev vacuum siv los tsim cov khoom siv purity siab. Cov txheej txheem no feem ntau yog siv nyob rau hauv lub chaw tsim khoom semiconductor los tsim cov yeeb yaj kiab nyias ntawm qhov chaw ntawm wafers. Nyob rau hauv tus txheej txheem ntawm kev npaj silicon carbide los ntawm CVD, lub substrate yog raug rau ib los yog ntau tshaj volatile precursors, uas reacts chemically nyob rau ntawm lub substrate rau deposit qhov xav tau silicon carbide deposits. Ntawm ntau txoj hauv kev los npaj cov ntaub ntawv silicon carbide, cov khoom npaj los ntawm cov tshuaj vapor deposition muaj ntau dua uniformity thiab purity, thiab txoj kev no muaj zog cov txheej txheem controllability. CVD silicon carbide cov ntaub ntawv muaj kev sib xyaw ua ke zoo heev ntawm cov khoom siv thermal, hluav taws xob thiab tshuaj lom neeg, ua rau lawv tsim nyog siv rau hauv kev lag luam semiconductor qhov twg cov ntaub ntawv ua tau zoo yuav tsum tau ua. CVD silicon carbide Cheebtsam yog dav siv nyob rau hauv etching khoom, MOCVD khoom, Si epitaxial khoom thiab SiC epitaxial khoom, ceev ceev thermal ua khoom thiab lwm yam teb.
Kab lus no tsom mus rau kev txheeb xyuas qhov zoo ntawm cov yeeb yaj kiab nyias uas loj hlob ntawm cov txheej txheem sib txawv thaum lub sijhawm npajCVD SiC txheej, thiaj li xaiv cov txheej txheem tsim nyog tshaj plaws. Qhov kev sim siv graphite ua lub substrate thiab trichloromethylsilane (MTS) ua cov tshuaj tiv thaiv qhov chaw roj. SiC txheej yog tso los ntawm cov txheej txheem qis CVD, thiab micromorphology ntawm covCVD SiC txheejyog soj ntsuam los ntawm scanning electron microscopy los soj ntsuam nws cov qauv ntom.
Vim tias qhov kub thiab txias ntawm cov graphite substrate yog siab heev, cov roj nruab nrab yuav raug desorbed thiab tawm ntawm lub substrate nto, thiab thaum kawg cov C thiab Si seem ntawm lub substrate nto yuav tsim cov theem SiC los ua SiC txheej. Raws li cov txheej txheem kev loj hlob ntawm CVD-SiC saum toj no, nws tuaj yeem pom tau tias qhov kub thiab txias yuav cuam tshuam rau qhov sib txawv ntawm cov pa, qhov decomposition ntawm MTS, tsim cov tee dej thiab desorption thiab tso tawm ntawm cov pa nruab nrab, yog li qhov kub ntawm deposition yuav ua lub luag haujlwm tseem ceeb hauv morphology ntawm SiC txheej. Lub microscopic morphology ntawm txheej yog qhov feem ntau intuitive manifestation ntawm qhov ntom ntawm txheej. Yog li ntawd, nws yog ib qho tsim nyog los kawm txog cov txiaj ntsig ntawm qhov sib txawv ntawm qhov kub thiab txias ntawm lub tshuab microscopic morphology ntawm CVD SiC txheej. Txij li thaum MTS tuaj yeem decompose thiab tso SiC txheej ntawm 900 ~ 1600 ℃, qhov kev sim no xaiv tsib qhov kub ntawm 900 ℃, 1000 ℃ , 1100 ℃ , 1200 ℃ thiab 1300 ℃ rau kev npaj SiC txheej los kawm txog qhov kub thiab txias ntawm CVD-SiC txheej. Cov kev txwv tshwj xeeb muaj nyob rau hauv Table 3. Daim duab 2 qhia tau hais tias lub microscopic morphology ntawm CVD-SiC txheej loj hlob ntawm qhov sib txawv deposition kub.
Thaum lub deposition kub yog 900 ℃, tag nrho SiC loj hlob mus rau hauv fiber ntau duab. Nws tuaj yeem pom tau tias txoj kab uas hla ntawm ib qho fiber ntau yog li 3.5μm, thiab nws qhov sib piv yog li 3 (<10). Ntxiv mus, nws yog tsim los ntawm suav tsis txheeb nano-SiC hais, yog li nws belongs rau polycrystalline SiC qauv, uas txawv ntawm cov tsoos SiC nanowires thiab ib leeg-crystal SiC whiskers. Qhov fibrous SiC no yog ib qho teeb meem ntawm cov qauv tsim los ntawm cov txheej txheem tsis tsim nyog. Nws tuaj yeem pom tau tias cov qauv ntawm SiC txheej no kuj xoob, thiab muaj ntau qhov pores ntawm fibrous SiC, thiab qhov ceev yog tsawg heev. Yog li ntawd, qhov kub thiab txias no tsis haum rau kev npaj cov txheej tuab SiC. Feem ntau, fibrous SiC cov yam ntxwv tsis xws luag yog tshwm sim los ntawm qhov kub thiab txias heev deposition. Ntawm qhov kub thiab txias, cov me me molecules adsorbed rau ntawm qhov chaw ntawm lub substrate muaj lub zog tsawg thiab tsis muaj peev xwm tsiv teb tsaws. Yog li ntawd, cov molecules me me yuav tsiv mus nyob thiab loj hlob mus rau qhov qis tshaj plaws uas tsis muaj zog ntawm SiC nplej (xws li lub taub ntawm cov nplej). Kev loj hlob tsis tu ncua nws thiaj li tsim fibrous SiC yam ntxwv tsis xws luag.
Kev npaj ntawm CVD SiC txheej:
Ua ntej, cov graphite substrate yog muab tso rau hauv lub tshuab nqus tsev kub kub thiab khaws cia ntawm 1500 ℃ rau 1h nyob rau hauv ib qho chaw Ar rau cov tshauv tshem tawm. Tom qab ntawd cov graphite block raug txiav mus rau hauv ib qho thaiv ntawm 15x15x5mm, thiab qhov saum npoo ntawm graphite block yog polished nrog 1200-mesh sandpaper kom tshem tawm cov pores saum npoo uas cuam tshuam rau cov deposition ntawm SiC. Kev kho graphite thaiv yog ntxuav nrog anhydrous ethanol thiab dej distilled, thiab tom qab ntawd muab tso rau hauv qhov cub ntawm 100 ℃ kom qhuav. Thaum kawg, graphite substrate yog muab tso rau hauv qhov chaw kub kub ntawm tubular rauv rau SiC deposition. Daim duab schematic ntawm cov tshuaj vapor deposition system yog qhia nyob rau hauv daim duab 1.
CovCVD SiC txheejtau soj ntsuam los ntawm scanning electron microscopy los soj ntsuam nws cov particle loj thiab ceev. Tsis tas li ntawd, tus nqi deposition ntawm SiC txheej yog xam raws li cov qauv hauv qab no: VSiC = (m2-m1)/(Sxt)x100% VSiC = Deposition rate; m2-nplua nuj txheej (mg); m1-mas ntawm substrate (mg); S-surface cheeb tsam ntawm substrate (mm2); t-lub sij hawm deposition (h). CVD-SiC yog qhov nyuaj, thiab cov txheej txheem tuaj yeem ua tiav raws li hauv qab no: ntawm qhov kub thiab txias, MTS yuav raug thermal decomposition los tsim cov pa roj carbon thiab silicon qhov chaw me me molecules. Cov pa roj carbon monoxide me me feem ntau suav nrog CH3, C2H2 thiab C2H4, thiab cov khoom siv silicon me me feem ntau suav nrog SiCI2, SiCI3, thiab lwm yam; Cov pa roj carbon monoxide thiab silicon qhov chaw me me yuav raug thauj mus rau saum npoo ntawm graphite substrate los ntawm cov cab kuj roj thiab cov roj diluent, thiab tom qab ntawd cov me me molecules yuav adsorbed rau saum npoo ntawm substrate hauv daim ntawv ntawm adsorption, thiab tom qab ntawd cov tshuaj tiv thaiv yuav tshwm sim ntawm cov molecules me me los tsim cov tee me me uas maj mam loj hlob tuaj, thiab cov tshuaj tiv thaiv yuav tshwm sim, tsim los ntawm cov khoom nruab nrab (HCl gas); Thaum qhov kub nce mus txog 1000 ℃, qhov ntom ntawm SiC txheej tau zoo heev. Nws tuaj yeem pom tau tias feem ntau ntawm cov txheej txheej yog tsim los ntawm SiC nplej (txog 4μm hauv qhov loj), tab sis qee qhov fibrous SiC tsis xws luag kuj pom, uas qhia tau hais tias tseem muaj kev loj hlob ntawm SiC ntawm qhov kub thiab txias, thiab txheej txheej tseem tsis ntom txaus. Thaum qhov kub nce mus txog 1100 ℃, nws tuaj yeem pom tias SiC txheej yog tuab heev, thiab cov fibrous SiC tsis xws luag tau ploj mus. Cov txheej txheej yog tsim los ntawm cov kua dej zoo li SiC nrog ib txoj kab uas hla ntawm 5 ~ 10μm, uas yog sib xyaw ua ke. Qhov saum npoo ntawm cov khoom yog ntxhib heev. Nws yog tsim los ntawm countless nano-scale SiC nplej. Qhov tseeb, CVD-SiC txoj kev loj hlob ntawm 1100 ℃ tau dhau los tswj kev hloov pauv loj. Cov molecules me me adsorbed rau ntawm qhov chaw ntawm lub substrate muaj lub zog txaus thiab lub sijhawm rau nucleate thiab loj hlob rau hauv SiC nplej. SiC nplej sib xyaw ua cov tee dej loj. Nyob rau hauv qhov kev txiav txim ntawm lub zog saum npoo, feem ntau ntawm cov tee dej tshwm sim kheej kheej, thiab cov tee dej yog nruj nreem ua ke los ua ib txheej tuab SiC. Thaum qhov kub nce mus txog 1200 ℃, SiC txheej kuj yog ntom, tab sis SiC morphology ua ntau ridged thiab saum npoo ntawm txheej zoo li rougher. Thaum qhov kub nce mus txog 1300 ℃, ntau tus kheej kheej kheej kheej nrog txoj kab uas hla ntawm 3μm pom nyob rau saum npoo ntawm graphite substrate. Qhov no yog vim hais tias ntawm qhov kub thiab txias, SiC tau hloov mus rau hauv cov roj theem nucleation, thiab MTS decomposition tus nqi yog ceev heev. Cov molecules me me tau hnov mob thiab nucleated los ua SiC nplej ua ntej lawv tau adsorbed ntawm substrate nto. Tom qab cov nplej tsim cov khoom me me, lawv yuav poob hauv qab, nws thiaj li ua rau xoob SiC particle txheej nrog qhov tsis zoo. Pom tseeb, 1300 ℃ tsis tuaj yeem siv los ua qhov kub thiab txias ntawm SiC txheej tuab. Kev sib piv zoo qhia tau hais tias yog tias cov txheej tuab SiC yuav tsum tau npaj, qhov zoo tshaj plaws CVD deposition kub yog 1100 ℃.
Daim duab 3 qhia txog qhov tso nyiaj ntawm CVD SiC txheej ntawm qhov sib txawv ntawm qhov kub thiab txias. Raws li qhov kub ntawm deposition nce, qhov deposition tus nqi ntawm SiC txheej maj mam txo. Lub deposition tus nqi ntawm 900 ° C yog 0.352 mg·h-1 / mm2, thiab kev loj hlob ntawm fibers coj mus rau qhov ceev tshaj deposition tus nqi. Lub deposition tus nqi ntawm cov txheej uas siab tshaj plaws yog 0.179 mg·h-1 / mm2. Vim tias qhov tso tawm ntawm qee qhov SiC, qhov tso nyiaj ntawm 1300 ° C yog qhov qis tshaj, tsuas yog 0.027 mg·h-1 / mm2. Cov ntsiab lus: Qhov zoo tshaj plaws CVD deposition kub yog 1100 ℃. Tsis tshua muaj kub txhawb kev loj hlob ntawm SiC, thaum kub kub ua rau SiC tsim vapor deposition thiab ua rau nyias txheej. Nrog rau qhov nce ntawm deposition kub, lub deposition tus nqi ntawmCVD SiC txheejmaj mam txo.
Post lub sij hawm: May-26-2025