1. Njira zazikulu zopezera nthunzi ya mankhwala m'magazi
Kuyika kwa nthunzi ya plasma yowonjezereka (PECVD) ndi ukadaulo watsopano wokulitsa mafilimu owonda pogwiritsa ntchito mankhwala omwe amapangidwa ndi zinthu za gasi pogwiritsa ntchito plasma yotulutsa kuwala. Chifukwa ukadaulo wa PECVD umakonzedwa ndi kutulutsa mpweya, mawonekedwe a plasma yosagwirizana amagwiritsidwa ntchito bwino, ndipo njira yoperekera mphamvu ya dongosolo la reaction imasinthidwa kwambiri. Nthawi zambiri, ukadaulo wa PECVD ukagwiritsidwa ntchito pokonza mafilimu owonda, kukula kwa mafilimu owonda kumaphatikizapo njira zitatu zotsatirazi.
Choyamba, mu plasma yopanda kufanana, ma elekitironi amachitapo kanthu ndi mpweya wochitapo kanthu mu gawo loyamba kuti awononge mpweya wochitapo kanthu ndikupanga chisakanizo cha ma ayoni ndi magulu ogwira ntchito;
Kachiwiri, mitundu yonse ya magulu ogwira ntchito imafalikira ndikunyamula kupita pamwamba ndi pakhoma la filimuyo, ndipo zochitika zina pakati pa ma reactants zimachitika nthawi imodzi;
Pomaliza, mitundu yonse ya zinthu zoyambira ndi zachiwiri zomwe zimafika pamwamba pa kukula zimayamwa ndikuchitapo kanthu ndi pamwamba, limodzi ndi kutulutsidwanso kwa mamolekyu a mpweya.
Makamaka, ukadaulo wa PECVD wozikidwa pa njira yotulutsira kuwala ungapangitse kuti mpweya wochitapo kanthu ukhale ionis kuti upange plasma pansi pa kusonkhezera kwa mphamvu yamagetsi yakunja. Mu plasma yotulutsira kuwala, mphamvu ya kinetic ya ma elekitironi omwe amafulumizitsidwa ndi mphamvu yamagetsi yakunja nthawi zambiri amakhala pafupifupi 10ev, kapena kupitirira apo, zomwe zimakhala zokwanira kuwononga ma bond a mankhwala a mamolekyulu a mpweya wochitapo kanthu. Chifukwa chake, kudzera mu kugundana kwa ma elekitironi amphamvu kwambiri ndi mamolekyulu a mpweya wochitapo kanthu, mamolekyu a mpweya adzasinthidwa kukhala ioni kapena kuwola kuti apange ma atomu osalowerera komanso zinthu zamamolekyu. Ma ioni abwino amafulumizitsidwa ndi mphamvu yamagetsi ya ion layer ndikugundana ndi electrode yapamwamba. Palinso gawo laling'ono lamagetsi la ion layer pafupi ndi electrode yotsika, kotero gawo lapansi limawombedwanso ndi ma ioni pamlingo wina. Zotsatira zake, chinthu chosalowerera chomwe chimapangidwa ndi kuwonongeka chimafalikira ku khoma la chubu ndi substrate. Mu njira yosunthika ndi kufalikira, tinthu ndi magulu awa (ma atomu osalowerera ndi mamolekyulu omwe amagwira ntchito mwamankhwala amatchedwa magulu) adzakumana ndi njira ya molecule ya ion ndi gulu la molekyulu chifukwa cha njira yaifupi yaulere. Kapangidwe ka mankhwala a zinthu zogwira ntchito (makamaka magulu) zomwe zimafika pansi pake n’kuzithira m’madzi zimakhala zogwira ntchito kwambiri, ndipo filimuyo imapangidwa ndi kuyanjana pakati pawo.
2. Machitidwe a mankhwala mu plasma
Popeza kusonkhezera kwa mpweya wochitapo kanthu mu njira yotulutsira kuwala kumachokera makamaka ku kugundana kwa ma elekitironi, machitidwe oyambira mu plasma ndi osiyanasiyana, ndipo kuyanjana pakati pa plasma ndi pamwamba pa solid nakonso n'kovuta kwambiri, zomwe zimapangitsa kuti zikhale zovuta kuphunzira momwe njira ya PECVD imagwirira ntchito. Pakadali pano, machitidwe ambiri ofunikira a reaction akonzedwa bwino ndi zoyeserera kuti apeze mafilimu okhala ndi makhalidwe abwino. Pakuyika mafilimu opyapyala opangidwa ndi silicon kutengera ukadaulo wa PECVD, ngati njira yoyika ikhoza kuwululidwa mozama, kuchuluka kwa mafilimu opyapyala opangidwa ndi silicon kungathe kuwonjezeredwa kwambiri poganizira kuti zinthuzo zili ndi makhalidwe abwino kwambiri.
Pakadali pano, mu kafukufuku wa mafilimu opyapyala opangidwa ndi silicon, hydrogen diluted silane (SiH4) imagwiritsidwa ntchito kwambiri ngati mpweya woyankhira chifukwa pali kuchuluka kwa haidrojeni m'mafilimu opyapyala opangidwa ndi silicon. H imagwira ntchito yofunika kwambiri m'mafilimu opyapyala opangidwa ndi silicon. Imatha kudzaza zomangira zomwe zili mu kapangidwe ka zinthu, kuchepetsa kwambiri mphamvu ya chilema, ndikuzindikira mosavuta kuwongolera kwa ma elekitironi a valence a zinthuzo. Popeza spear et al. Anazindikira zotsatira za doping za mafilimu opyapyala a silicon ndipo adakonza mgwirizano woyamba wa PN mu, kafukufuku wokhudza kukonzekera ndi kugwiritsa ntchito mafilimu opyapyala opangidwa ndi silicon kutengera ukadaulo wa PECVD wapangidwa mwachangu kwambiri. Chifukwa chake, momwe mankhwala amachitira m'mafilimu opyapyala opangidwa ndi silicon omwe amaikidwa ndi ukadaulo wa PECVD adzafotokozedwa ndikukambidwa motere.
Pansi pa mkhalidwe wotulutsa kuwala, chifukwa ma elekitironi mu plasma ya silane ali ndi mphamvu zoposa zingapo za EV, H2 ndi SiH4 zimawonongeka zikagundana ndi ma elekitironi, zomwe ndi gawo la reaction yoyamba. Ngati sitiganizira za mikhalidwe yosangalatsa yapakati, titha kupeza zotsatirazi za dissociation reactions za sihm (M = 0,1,2,3) ndi 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)
Malinga ndi kutentha kokhazikika kwa kupanga mamolekyu a nthaka, mphamvu zomwe zimafunikira pa njira zolekanitsira zomwe zili pamwambapa (2.1) ~ (2.5) ndi 2.1, 4.1, 4.4, 5.9 EV ndi 4.5 EV motsatana. Ma electron amphamvu kwambiri mu plasma amathanso kuchita izi mwa ionization reactions.
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)
Mphamvu yofunikira pa (2.6) ~ (2.9) ndi 11.9, 12.3, 13.6 ndi 15.3 EV motsatana. Chifukwa cha kusiyana kwa mphamvu ya reaction, mwayi wa (2.1) ~ (2.9) reactions ndi wosiyana kwambiri. Kuphatikiza apo, sihm yopangidwa ndi reaction process (2.1) ~ (2.5) idzakumana ndi zotsatirazi zachiwiri kuti ionize, monga
SiH+e→SiH++2e (2.10)
SiH2+e→SiH2++2e (2.11)
SiH3+e→SiH3++2e (2.12)
Ngati zomwe zili pamwambapa zikuchitika pogwiritsa ntchito njira imodzi ya ma elekitironi, mphamvu yofunikira ndi pafupifupi 12 eV kapena kuposerapo. Poganizira kuti chiwerengero cha ma elekitironi amphamvu kwambiri pamwamba pa 10ev mu plasma yofooka ya ionized yokhala ndi kuchuluka kwa ma elekitironi a 1010cm-3 ndi chochepa pansi pa mphamvu yamlengalenga (10-100pa) yokonzekera mafilimu okhala ndi silicon, kuthekera kwa ionization kokwanira nthawi zambiri kumakhala kochepa kuposa kuthekera kwa kusonkhezera. Chifukwa chake, gawo la ma ionized omwe ali pamwambapa mu plasma ya silane ndi laling'ono kwambiri, ndipo gulu losalowerera la sihm ndilopambana. Zotsatira za kusanthula kwa mass spectrum zimatsimikiziranso izi [8]. Bourquard et al. Ananenanso kuti kuchuluka kwa sihm kunachepa motsatira dongosolo la sih3, sih2, Si ndi SIH, koma kuchuluka kwa SiH3 kunali kochepera katatu kuposa kwa SIH. Robertson et al. Ananenanso kuti muzinthu zosalowerera za sihm, silane yoyera imagwiritsidwa ntchito makamaka pakutulutsa mphamvu yayikulu, pomwe sih3 imagwiritsidwa ntchito makamaka pakutulutsa mphamvu yochepa. Dongosolo la kuchuluka kwa zinthu kuyambira pamwamba mpaka pansi linali SiH3, SiH, Si, SiH2. Chifukwa chake, magawo a njira ya plasma amakhudza kwambiri kapangidwe ka zinthu zopanda mphamvu za sihm.
Kuwonjezera pa kugawanika ndi kusinthasintha kwa ma ionization omwe ali pamwambapa, machitidwe achiwiri pakati pa mamolekyu a ionic nawonso ndi ofunikira kwambiri.
SiH2＋+SiH4→SiH3++SiH3 (2.13)
Chifukwa chake, pankhani ya kuchuluka kwa ma ion, sih3 + ndi yoposa sih2 +. Izi zitha kufotokoza chifukwa chake pali ma ion ambiri a sih3 + kuposa ma ion a sih2 + mu plasma ya SiH4.
Kuphatikiza apo, padzakhala kusintha kwa kugongana kwa maatomu a molekyulu pomwe maatomu a haidrojeni mu plasma amatenga haidrojeni mu SiH4
H+ SiH4→SiH3+H2 (2.14)
Ndi exothermic reaction komanso chitsogozo cha kupangidwa kwa si2h6. Zachidziwikire, magulu awa sali mu ground state yokha, komanso amasangalala ndi excited state mu plasma. Ma emission spectra a silane plasma akuwonetsa kuti pali optically admissible transition excited states a Si, SIH, h, ndi vibrational excited states a SiH2, SiH3.
Nthawi yotumizira: Epulo-07-2021