Itekhnoloji esisiseko yokufakwa komphunga wekhemikhali ophuculweyo ngeplasma (i-PECVD)

1. Iinkqubo eziphambili zokufakwa komphunga weekhemikhali ophuculweyo kwiplasma

Ukufakwa komphunga wekhemikhali ophuculweyo ngeplasma (i-PECVD) bubuchwepheshe obutsha bokukhula kweefilimu ezincinci nge-chemical reaction yezinto zegesi ngoncedo lwe-glow discharge plasma. Ngenxa yokuba ubuchwepheshe be-PECVD bulungiswa ngokukhutshwa kwegesi, iimpawu zempendulo ye-non-equilibrium plasma zisetyenziswa ngokufanelekileyo, kwaye indlela yokubonelela ngamandla yenkqubo yokusabela itshintsha ngokusisiseko. Ngokubanzi, xa ubuchwepheshe be-PECVD busetyenziselwa ukulungiselela iifilimu ezincinci, ukukhula kweefilimu ezincinci kubandakanya ikakhulu ezi nkqubo zintathu zilandelayo ezisisiseko.

Okokuqala, kwi-plasma engalinganiyo, ii-elektroni zisabela kunye negesi yokusabela kwinqanaba eliphambili ukuze zibolise igesi yokusabela kwaye zenze umxube wee-ions kunye namaqela asebenzayo;

Okwesibini, zonke iintlobo zamaqela asebenzayo ziyasasazeka kwaye zithutha ziye kumphezulu nasodongeni lwefilimu, kwaye ii-reaction zesibini phakathi kwee-reactants zenzeka ngaxeshanye;

Okokugqibela, zonke iintlobo zeemveliso zempendulo eziphambili nezesibini ezifikelela kumphezulu wokukhula ziyafunxwa kwaye zisabela kumphezulu, zihamba kunye nokukhululwa kwakhona kweemolekyuli zegesi.

Ngokukodwa, iteknoloji ye-PECVD esekelwe kwindlela yokukhupha ukukhanya ingenza igesi yokusabela ibe yi-ionize ukuze yenze i-plasma phantsi koxinzelelo lwentsimi ye-electromagnetic yangaphandle. Kwi-plasma yokukhupha ukukhanya, amandla e-kinetic ee-electron akhawuleziswa yintsimi yombane yangaphandle adla ngokuba malunga ne-10ev, okanye ngaphezulu, nto leyo eyaneleyo ukutshabalalisa iibhondi zeekhemikhali zeemolekyuli zegesi ezisebenzayo. Ke ngoko, ngokungqubana kwe-inelastic kwee-electron ezinamandla aphezulu kunye neemolekyuli zegesi ezisebenzayo, iimolekyuli zegesi ziya kwenziwa i-ion okanye zibole ukuze kuveliswe ii-athomu ezingathathi cala kunye neemveliso zemolekyuli. Ii-ion ezilungileyo ziyakhawuleziswa yi-ion layer ekhawulezisa intsimi yombane kwaye zingqubane ne-electrode ephezulu. Kukwakho nentsimi yombane ye-ion layer encinci kufutshane ne-electrode esezantsi, ngoko ke i-substrate nayo iqhunyiswa zii-ion ukuya kwinqanaba elithile. Ngenxa yoko, into engathathi cala eveliswa kukubola iyasasazeka eludongeni lwetyhubhu kunye ne-substrate. Kwinkqubo yokushukuma nokusasazwa, la masuntswana kunye namaqela (ii-athomu ezingathathi cala ezisebenzayo kunye neemolekyuli zibizwa ngokuba ngamaqela) ziya kungena kwi-ion molecule reaction kunye ne-group molecule reaction ngenxa yendlela emfutshane ekhululekileyo. Iimpawu zeekhemikhali zezinto ezisebenzayo zeekhemikhali (ikakhulu amaqela) ezifikelela kwi-substrate kwaye zifunxwe zisebenza kakhulu, kwaye ifilimu yenziwa kukusebenzisana phakathi kwazo.

2. Iimpendulo zeekhemikhali kwi-plasma

Ngenxa yokuba ukuvuselelwa kwegesi yokusabela kwinkqubo yokukhupha ukukhanya ikakhulu kukungqubana kwee-electron, ii-reactions zokuqala kwi-plasma zahlukile, kwaye ukusebenzisana phakathi kwe-plasma kunye nomphezulu oqinileyo nako kuyinkimbinkimbi kakhulu, okwenza kube nzima ukufunda indlela yokusebenza kwenkqubo ye-PECVD. Okwangoku, iinkqubo ezininzi ezibalulekileyo zokusabela ziye zalungiswa ngovavanyo lokufumana iifilimu ezineempawu ezifanelekileyo. Ukubekwa kweefilimu ezincinci ezisekelwe kwi-silicon ngokusekelwe kwitekhnoloji ye-PECVD, ukuba indlela yokufaka inokutyhilwa nzulu, izinga lokubekwa kweefilimu ezincinci ezisekelwe kwi-silicon linokwandiswa kakhulu ngesiseko sokuqinisekisa iipropati zomzimba ezilungileyo zezinto.

Okwangoku, kuphando lweefilimu ezibhityileyo ezisekelwe kwisilicon, i-hydrogen diluted silane (SiH4) isetyenziswa kakhulu njengegesi yokusabela kuba kukho inani elithile le-hydrogen kwiifilimu ezibhityileyo ezisekelwe kwisilicon. I-H idlala indima ebaluleke kakhulu kwiifilimu ezibhityileyo ezisekelwe kwisilicon. Ingazalisa iibhondi ezixhonyiweyo kwisakhiwo sezinto, inciphise kakhulu inqanaba lamandla angalunganga, kwaye ikwazi ukufezekisa ulawulo lwe-valence electron lwezixhobo. Ukususela ekuqaleni, i-spear et al. yaqaphela isiphumo sokudaya iifilimu ezibhityileyo zesilicon kwaye yalungiselela i-PN junction yokuqala, uphando malunga nokulungiswa kunye nokusetyenziswa kweefilimu ezibhityileyo ezisekelwe kwisilicon ezisekelwe kwiteknoloji yePECVD luye lwaphuhliswa ngokukhawuleza. Ke ngoko, impendulo yeekhemikhali kwiifilimu ezibhityileyo ezisekelwe kwisilicon ezifakwe yiteknoloji yePECVD iya kuchazwa kwaye ixoxwe ngayo kulandelayo.

Phantsi kwemeko yokukhupha ukukhanya, kuba ii-elektroni ezikwi-plasma ye-silane zinamandla e-EV angaphezu kwamaqela amaninzi, i-H2 kunye ne-SiH4 ziya kubola xa zingqubana nee-elektroni, eziyinxalenye yempendulo ephambili. Ukuba asicingi ngeemeko ezivuyayo eziphakathi, sinokufumana ezi mpendulo zilandelayo ze-sihm (M = 0,1,2,3) kunye ne-H.

e+SiH4→SiH2+H2+e (2.1)

e+SiH4→SiH3+ H+e (2.2)

e+SiH4→Si+2H2+e (2.3)

e+SiH4→SiH+H2+H+e (2.4)

e+H2→2H+e (2.5)

Ngokweqondo lobushushu obuqhelekileyo bokuveliswa kweemolekyuli zomhlaba, amandla afunekayo kwiinkqubo zokuhlukana ezingasentla (2.1) ~ (2.5) yi-2.1, 4.1, 4.4, 5.9 EV kunye ne-4.5 EV ngokwahlukeneyo. Ii-electron zamandla aphezulu kwi-plasma nazo zinokudlula kwezi mpendulo ze-ionization zilandelayo.

e+SiH4→SiH2++H2+2e (2.6)

e+SiH4→SiH3++ H+2e (2.7)

e+SiH4→Si++2H2+2e (2.8)

e+SiH4→SiH++H2+H+2e (2.9)

Amandla afunekayo kwi-(2.6) ~ (2.9) yi-11.9, 12.3, 13.6 kunye ne-15.3 EV ngokwahlukeneyo. Ngenxa yomahluko wamandla okusabela, amathuba okusabela kwe-(2.1) ~ (2.9) awalingani kakhulu. Ukongeza, i-sihm eyenziwe ngenkqubo yokusabela (2.1) ~ (2.5) iya kudlula kwezi mpendulo zesibini zilandelayo ukuze i-ionize, ezifana

I-SiH+e→I-SiH++2e (2.10)

I-SiH2+e→I-SiH2++2e (2.11)

I-SiH3+e→I-SiH3++2e (2.12)

Ukuba le mpendulo ingentla yenziwa ngenkqubo enye ye-electron, amandla afunekayo amalunga ne-12 eV okanye ngaphezulu. Ngenxa yokuba inani lee-electron ezinamandla aphezulu ngaphezulu kwe-10ev kwi-plasma ene-ionized ebuthathaka ene-electron density ye-1010cm-3 lincinci kakhulu phantsi koxinzelelo lomoya (10-100pa) ukulungiselela iifilimu ezisekwe kwi-silicon, amathuba e-ionization aqokelelweyo ngokubanzi aphantsi kunomngcipheko wokuvuselela. Ke ngoko, umlinganiselo wee-ionized compounds ezingentla kwi-silane plasma umncinci kakhulu, kwaye iqela elingathathi cala le-sihm liphezulu. Iziphumo zohlalutyo lwe-mass spectrum nazo zingqina esi sigqibo [8]. UBourquard et al. Baqhubela phambili bathi uxinzelelo lwe-sihm lwehle ngolandelelwano lwe-sih3, sih2, Si kunye ne-SIH, kodwa uxinzelelo lwe-SiH3 beluphindwe kathathu kunolwe-SIH. URobertson et al. Baxele ukuba kwiimveliso ezingathathi cala ze-sihm, i-silane ecocekileyo yayisetyenziswa kakhulu ekukhupheni amandla aphezulu, ngelixa i-sih3 yayisetyenziswa kakhulu ekukhupheni amandla aphantsi. Ulandelelwano loxinzelelo ukusuka phezulu ukuya kwezantsi yayiyiSiH3, iSiH, iSi, iSiH2. Ke ngoko, iiparameter zenkqubo yeplasma zichaphazela kakhulu ukwakheka kweemveliso ezingathathi cala ze-sihm.

Ukongeza kwiimpendulo zokuhlukana kunye ne-ionization ezingentla, iimpendulo zesibini phakathi kwee-molecule ze-ionic nazo zibaluleke kakhulu.

SiH2＋+SiH4→SiH3++SiH3 (2.13)

Ngoko ke, ngokwengxinano yee-ion, i-sih3 + ingaphezulu kwe-sih2+. Ingachaza ukuba kutheni kukho ii-sih3 + ii-ion ezingaphezulu kunee-sih2 + ii-ion kwi-plasma ye-SiH4.

Ukongeza, kuya kubakho impendulo yokungqubana kweeathom zemolekyuli apho iiathom zehydrogen kwiplasma zibamba ihydrogen kwiSiH4

H+ SiH4→SiH3+H2 (2.14)

Yimpendulo ye-exothermic kunye nomphambili wokwenziwa kwe-si2h6. Kakade ke, la maqela akapheleli nje kwimeko yomhlaba, kodwa akwanomdla kwimeko yovuyo kwi-plasma. Ii-spectra zokukhupha i-silane plasma zibonisa ukuba kukho iimeko zovuyo zotshintsho ezivunyiweyo ze-Si, SIH, h, kunye neemeko zovuyo ezivuthuzayo ze-SiH2, SiH3.