Ubuchwepheshe obuyisisekelo bokufakwa komphunga wamakhemikhali othuthukisiwe nge-plasma (i-PECVD)

1. Izinqubo eziyinhloko zokufakwa komphunga wamakhemikhali okuthuthukisiwe nge-plasma

Ukufakwa komoya wamakhemikhali othuthukisiwe nge-plasma (i-PECVD) ubuchwepheshe obusha bokukhula kwamafilimu amancane ngokusabela kwamakhemikhali kwezinto zegesi ngosizo lwe-plasma ekhishwa ukukhanya. Ngenxa yokuthi ubuchwepheshe be-PECVD bulungiswa ngokukhishwa kwegesi, izici zokusabela kwe-plasma engalingani zisetshenziswa ngempumelelo, futhi indlela yokunikezwa kwamandla yesistimu yokusabela ishintsha ngokuyisisekelo. Ngokuvamile, lapho ubuchwepheshe be-PECVD busetshenziswa ukulungiselela amafilimu amancane, ukukhula kwamafilimu amancane kuhlanganisa kakhulu izinqubo ezintathu eziyisisekelo ezilandelayo.

Okokuqala, ku-plasma engalingani, ama-electron asabela negesi yokusabela esigabeni esiyinhloko ukuze ahlukanise igesi yokusabela futhi akhe ingxube yama-ion namaqembu asebenzayo;

Okwesibili, zonke izinhlobo zamaqembu asebenzayo ziyasabalala futhi zithuthele phezulu nasodongeni lwefilimu, kanti ukusabela kwesibili phakathi kwama-reactants kwenzeka ngesikhathi esifanayo;

Okokugcina, zonke izinhlobo zemikhiqizo yokusabela okuyinhloko nokwesibili efika endaweni yokukhula iyamuncwa futhi isabela endaweni, kuhambisana nokukhululwa kabusha kwama-molecule egesi.

Ngokukhethekile, ubuchwepheshe be-PECVD obusekelwe endleleni yokukhipha ukukhanya bungenza igesi yokusabela ibe yi-ionize ukuze yakhe i-plasma ngaphansi kokuvusa insimu ye-electromagnetic yangaphandle. Ku-plasma yokukhipha ukukhanya, amandla e-kinetic ama-electron asheshiswa yinsimu kagesi yangaphandle ngokuvamile angaba ngu-10ev, noma ngaphezulu, okwanele ukubhubhisa izibopho zamakhemikhali zama-molecule egesi asebenzayo. Ngakho-ke, ngokushayisana kwe-inelastic kwama-electron anamandla aphezulu nama-molecule egesi asebenzayo, ama-molecule egesi azoguqulwa abe yi-ion noma ahlukaniswe ukuze akhiqize ama-athomu angathathi hlangothi kanye nemikhiqizo yama-molecule. Ama-ion amahle asheshiswa yinsimu kagesi ye-ion esheshisa ungqimba lwe-ion futhi ashayisane ne-electrode engenhla. Kukhona nensimu kagesi yengqimba ye-ion encane eduze kwe-electrode engezansi, ngakho-ke i-substrate nayo ihlaselwa ama-ion ngezinga elithile. Ngenxa yalokho, into engathathi hlangothi ekhiqizwa ukubola iyasakazeka odongeni lweshubhu kanye ne-substrate. Enkambisweni yokukhukhuleka nokusabalalisa, lezi zinhlayiya namaqembu (ama-athomu angathathi hlangothi amakhemikhali nama-molecule abizwa ngokuthi amaqembu) azobhekana nokusabela kwe-ion molecule kanye nokusabela kwe-molecule yeqembu ngenxa yendlela emfushane evamile yamahhala. Izakhiwo zamakhemikhali zezinto ezisebenzayo zamakhemikhali (ikakhulukazi amaqembu) ezifika ku-substrate futhi zifakwe emanzini zisebenza kakhulu, futhi ifilimu yakhiwa ngokusebenzisana kwazo.

2. Ukusabela kwamakhemikhali ku-plasma

Ngenxa yokuthi ukuvusa kwegesi yokusabela enkambisweni yokukhipha ukukhanya kubangelwa kakhulu ukushayisana kwama-electron, ukusabela okuyisisekelo ku-plasma kuyahlukahluka, futhi ukusebenzisana phakathi kwe-plasma kanye nobuso obuqinile nakho kuyinkimbinkimbi kakhulu, okwenza kube nzima kakhulu ukutadisha indlela yokusebenza kwenqubo ye-PECVD. Kuze kube manje, izinhlelo eziningi zokusabela ezibalulekile zenziwe ngcono ngokuhlolwa ukuthola amafilimu anezakhiwo ezifanelekile. Ukuze kufakwe amafilimu amancane asekelwe ku-silicon asekelwe kubuchwepheshe be-PECVD, uma indlela yokufaka ingadalulwa ngokujulile, izinga lokufakwa kwamafilimu amancane asekelwe ku-silicon lingakhushulwa kakhulu ngesisekelo sokuqinisekisa izakhiwo zomzimba ezinhle kakhulu zezinto.

Njengamanje, ocwaningweni lwamafilimu amancane asekelwe ku-silicon, i-hydrogen diluted silane (SiH4) isetshenziswa kabanzi njengegesi yokusabela ngoba kunesilinganiso esithile se-hydrogen kumafilimu amancane asekelwe ku-silicon. I-H idlala indima ebaluleke kakhulu kumafilimu amancane asekelwe ku-silicon. Ingagcwalisa izibopho ezilengayo esakhiweni sezinto ezibonakalayo, yehlise kakhulu izinga lamandla angalungile, futhi ibone kalula ukulawulwa kwe-valence electron kwezinto. Njengoba i-spear et al. Yaqala ukuqaphela umphumela wokusebenzisa izidakamizwa wamafilimu amancane e-silicon futhi yalungisa ukuhlangana kokuqala kwe-PN, ucwaningo lokulungiselela nokusetshenziswa kwamafilimu amancane asekelwe ku-silicon asekelwe kubuchwepheshe be-PECVD luye lwathuthukiswa ngokushesha okukhulu. Ngakho-ke, ukusabela kwamakhemikhali kumafilimu amancane asekelwe ku-silicon afakwe ubuchwepheshe be-PECVD kuzochazwa futhi kuxoxwe ngakho okulandelayo.

Ngaphansi kwesimo sokukhishwa kokukhanya, ngoba ama-electron aku-plasma ye-silane anamandla e-EV angaphezu kweminingana, i-H2 ne-SiH4 zizobola lapho zishayisana nama-electron, okuyingxenye yokusabela okuyinhloko. Uma singacabangi ngezimo ezijabulisayo eziphakathi nendawo, singathola ukusabela okulandelayo kokuhlukaniswa kwe-sihm (M = 0,1,2,3) 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)

Ngokusho kokushisa okujwayelekile kokukhiqizwa kwama-molecule esimo somhlabathi, amandla adingekayo ezinqubweni zokuhlukaniswa ezingenhla (2.1) ~ (2.5) angama-2.1, 4.1, 4.4, 5.9 EV kanye no-4.5 EV ngokulandelana. Ama-electron anamandla aphezulu ku-plasma nawo angabhekana nokusabela okulandelayo kwe-ionization

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 adingekayo ku-(2.6) ~ (2.9) angu-11.9, 12.3, 13.6 kanye no-15.3 EV ngokulandelana. Ngenxa yomehluko wamandla okusabela, amathuba okusabela ku-(2.1) ~ (2.9) awalingani kakhulu. Ngaphezu kwalokho, i-sihm eyakhiwe ngenqubo yokusabela (2.1) ~ (2.5) izobhekana nokusabela okulandelayo kwesibili ukuze i-ionize, njengokuthi

I-SiH+e→I-SiH++2e (2.10)

I-SiH2+e→I-SiH2++2e (2.11)

I-SiH3+e→I-SiH3++2e (2.12)

Uma ukusabela okungenhla kwenziwa ngenqubo eyodwa ye-electron, amandla adingekayo angaba ngu-12 eV noma ngaphezulu. Ngenxa yokuthi inani lama-electron anamandla aphezulu ngaphezu kwe-10ev ku-plasma ebuthakathaka ene-electron density engu-1010cm-3 lincane kakhulu ngaphansi kwengcindezi yomoya (10-100pa) yokulungiselela amafilimu asekelwe ku-silicon, amathuba okuhlangana kwe-ionization ngokuvamile mancane kakhulu kunamathuba okuvuselela. Ngakho-ke, ingxenye yamakhemikhali e-ionized angenhla ku-plasma ye-silane incane kakhulu, futhi iqembu elingathathi hlangothi le-sihm liphakeme. Imiphumela yokuhlaziywa kwe-mass spectrum nayo ifakazela lesi siphetho [8]. UBourquard et al. Baphinde baveza ukuthi ukuhlushwa kwe-sihm kwehle ngokulandelana kwe-sih3, sih2, Si kanye ne-SIH, kodwa ukuhlushwa kwe-SiH3 kwakungaphezu kokuphindwe kathathu kune-SIH. URobertson et al. Babike ukuthi emikhiqizweni engathathi hlangothi ye-sihm, i-silane emsulwa yayisetshenziswa kakhulu ekukhishweni kwamandla aphezulu, kuyilapho i-sih3 yayisetshenziswa kakhulu ekukhishweni kwamandla aphansi. Ukuhleleka kokuhlushwa kusukela phezulu kuya phansi kwakuyi-SiH3, i-SiH, i-Si, i-SiH2. Ngakho-ke, amapharamitha enqubo ye-plasma athinta kakhulu ukwakheka kwemikhiqizo engathathi hlangothi ye-sihm.

Ngaphezu kokusabela kokuhlukaniswa okungenhla kanye ne-ionization, ukusabela kwesibili phakathi kwama-molecule e-ionic nakho kubaluleke kakhulu.

SiH2＋+SiH4→SiH3++SiH3 (2.13)

Ngakho-ke, maqondana nokuhlushwa kwama-ion, i-sih3 + ingaphezu kwe-sih2 +. Kungachaza ukuthi kungani kunama-ion amaningi e-sih3 + kunama-ion e-sih2 + ku-plasma ye-SiH4.

Ngaphezu kwalokho, kuzoba nokusabela kokushayisana kwama-athomu ama-molecule lapho ama-athomu e-hydrogen e-plasma ebamba i-hydrogen ku-SiH4

H+ SiH4→SiH3+H2 (2.14)

Kuyimpendulo ye-exothermic kanye nesandulela sokwakheka kwe-si2h6. Vele, la maqembu awagcini nje ngokuba sesimweni somhlaba, kodwa futhi ajabule ngesimo sokuzijabulisa ku-plasma. Ama-spectra okukhishwa kwe-plasma ye-silane abonisa ukuthi kunezimo ezivuselelwe zokuguquguquka ezivumelekile ze-Si, SIH, h, kanye nezimo ezivuselelwe zokudlidliza ze-SiH2, SiH3.