Cov Txheej Txheem Qhia Txog SiC Epitaxial Kev Loj Hlob

Epitaxial txheej yog ib qho tshwj xeeb siv lead ua zaj duab xis cog rau ntawm wafer los ntawm cov txheej txheem epitaxial, thiab cov substrate wafer thiab epitaxial zaj duab xis hu ua epitaxial wafer. Los ntawm kev loj hlob ntawm silicon carbide epitaxial txheej ntawm cov khoom siv silicon carbide substrate, silicon carbide homogeneous epitaxial wafer tuaj yeem npaj ntxiv rau hauv Schottky diodes, MOSFETs, IGBTs thiab lwm yam khoom siv hluav taws xob, ntawm cov 4H-SiC substrate yog feem ntau siv.

Vim tias cov txheej txheem tsim khoom sib txawv ntawm silicon carbide lub zog hluav taws xob thiab cov cuab yeej siv hluav taws xob silicon, nws tsis tuaj yeem ncaj qha fabricated ntawm silicon carbide ib qho khoom siv lead ua. Ntxiv cov ntaub ntawv zoo epitaxial yuav tsum tau cog rau ntawm cov khoom siv lead ua ib leeg, thiab ntau yam khoom siv yuav tsum tau tsim nyob rau ntawm txheej epitaxial. Yog li ntawd, qhov zoo ntawm cov txheej txheem epitaxial muaj kev cuam tshuam zoo rau kev ua haujlwm ntawm cov cuab yeej. Kev txhim kho ntawm kev ua tau zoo ntawm cov khoom siv hluav taws xob sib txawv kuj tso siab rau cov kev xav tau siab dua rau cov thickness ntawm epitaxial txheej, doping concentration thiab tsis xws luag.

FIG. 1. Kev sib raug zoo ntawm doping concentration thiab thickness ntawm epitaxial txheej ntawm unipolar ntaus ntawv thiab thaiv voltage

Txoj kev npaj ntawm SIC epitaxial txheej feem ntau suav nrog evaporation txoj kev loj hlob, kua theem epitaxial kev loj hlob (LPE), molecular beam epitaxial loj hlob (MBE) thiab tshuaj vapor deposition (CVD). Tam sim no, tshuaj vapor deposition (CVD) yog txoj hauv kev tseem ceeb siv rau kev tsim khoom loj hauv cov chaw tsim khoom.

FIG. 2. Kev sib piv ntawm cov txheej txheem tseem ceeb ntawm cov txheej txheem epitaxial

Ntawm qhov off-axis {0001} substrate nrog ib qho qaij lub kaum sab xis, raws li qhia hauv daim duab 2(b), qhov ceev ntawm cov kauj ruam saum npoo yog loj dua, thiab qhov luaj li cas ntawm cov kauj ruam saum npoo yog me dua, thiab siv lead ua nucleation tsis yooj yim rau tshwm sim ntawm cov kauj ruam saum npoo, tab sis ntau zaus tshwm sim ntawm qhov sib koom ua ke ntawm cov kauj ruam. Hauv qhov no, tsuas muaj ib qho tseem ceeb nucleating. Yog li ntawd, cov txheej txheem epitaxial tuaj yeem ua tau zoo dua qhov kev txiav txim stacking ntawm lub substrate, yog li tshem tawm cov teeb meem ntawm ntau hom coexistence.

FIG. 3. Daim duab txheej txheem lub cev ntawm 4H-SiC kauj ruam tswj epitaxy txoj kev

FIG. 4. Cov xwm txheej tseem ceeb rau CVD kev loj hlob los ntawm 4H-SiC kauj ruam-tswj epitaxy txoj kev

FIG. 5. Kev sib piv ntawm kev loj hlob nyob rau hauv qhov sib txawv silicon hauv 4H-SiC epitaxy

Tam sim no, silicon carbide epitaxy thev naus laus zis yog qhov paub tab hauv kev siv hluav taws xob tsawg thiab nruab nrab (xws li 1200 volt li). Lub thickness uniformity, doping concentration uniformity thiab defect tis ntawm epitaxial txheej yuav ncav cuag ib tug kuj zoo theem, uas muaj peev xwm ua tau raws li qhov xav tau ntawm nruab nrab thiab tsawg voltage SBD (Schottky diode), MOS (hlau oxide semiconductor field effect transistor), JBS ( junction diode) thiab lwm yam khoom siv.

Txawm li cas los xij, nyob rau hauv kev kub siab, epitaxial wafers tseem yuav tsum tau kov yeej ntau yam kev sib tw. Piv txwv li, rau cov khoom siv uas yuav tsum tau tiv taus 10,000 volts, lub thickness ntawm epitaxial txheej yuav tsum yog li 100μm. Piv nrog rau cov khoom siv hluav taws xob tsawg, lub thickness ntawm cov txheej epitaxial thiab cov uniformity ntawm doping concentration yog txawv ntau, tshwj xeeb tshaj yog cov uniformity ntawm doping concentration. Nyob rau tib lub sijhawm, daim duab peb sab tsis xws luag hauv txheej epitaxial tseem yuav rhuav tshem tag nrho kev ua haujlwm ntawm lub cuab yeej. Hauv cov ntawv thov high-voltage, cov cuab yeej siv tau zoo siv cov khoom siv bipolar, uas yuav tsum muaj lub neej tsawg tsawg hauv cov txheej txheem epitaxial, yog li cov txheej txheem yuav tsum tau ua kom zoo dua qub los txhim kho cov haiv neeg tsawg.

Tam sim no, cov epitaxy hauv tsev feem ntau yog 4 ntiv tes thiab 6 ntiv tes, thiab feem ntau ntawm silicon carbide epitaxy yog nce txhua xyoo. Qhov loj ntawm silicon carbide epitaxial daim ntawv yog tsuas yog txwv los ntawm qhov loj ntawm silicon carbide substrate. Tam sim no, 6-nti silicon carbide substrate tau ua lag luam, yog li cov silicon carbide epitaxial maj mam hloov ntawm 4 ntiv mus rau 6 ntiv tes. Nrog kev txhim kho txuas ntxiv ntawm silicon carbide substrate npaj thev naus laus zis thiab muaj peev xwm nthuav dav, tus nqi ntawm silicon carbide substrate yog maj mam txo. Nyob rau hauv muaj pes tsawg leeg ntawm tus nqi ntawm daim ntawv epitaxial, lub substrate account rau ntau tshaj 50% ntawm tus nqi, yog li nrog qhov poob ntawm cov substrate nqi, tus nqi ntawm silicon carbide epitaxial daim ntawv kuj yuav tsum tau txo.