Ukucwiliswa okumanzi kwangaphambi kwesikhathi kwakhuthaza ukuthuthukiswa kwezinqubo zokuhlanza noma zomlotha. Namuhla, ukomisa okomile usebenzisa i-plasma sekuyinto evamileinqubo etching. I-Plasma iqukethe ama-electron, ama-cations nama-radicals. Amandla asetshenziswa ku-plasma abangela ukuthi ama-electron angaphandle egesi yomthombo asesimweni sokungathathi hlangothi asuswe, ngaleyo ndlela aguqule lawa ma-electron abe ama-cation.
Ngaphezu kwalokho, ama-athomu angaphelele kuma-molecule angasuswa ngokusebenzisa amandla ukuze akhe ama-radicals kagesi angathathi hlangothi. I-Dry etching isebenzisa ama-cations nama-radicals akha i-plasma, lapho ama-cation e-anisotropic (efanele ukushumeka endaweni ethile) futhi ama-radicals ayi-isotropic (afanele ukushumeka kuzo zonke izinhlangothi). Inani lama-radicals likhulu kakhulu kunenombolo yama-cation. Kulokhu, i-etching eyomile kufanele ibe yi-isotropic njenge-etching emanzi.
Kodwa-ke, i-anisotropic etching ye-etching eyomile eyenza amasekhethi e-ultra-miniaturized enzeke. Siyini isizathu salokhu? Ngaphezu kwalokho, isivinini sokufaka ama-cations nama-radicals sihamba kancane kakhulu. Ngakho-ke singazisebenzisa kanjani izindlela zokufaka i-plasma ekukhiqizeni ngobuningi lapho sibhekene nalokhu kushiyeka?
1. I-Aspect ratio (A/R)
Umfanekiso 1. Umqondo we-aspect ratio nomthelela wenqubekelaphambili yezobuchwepheshe kuwo
I-Aspect Ratio isilinganiso sobubanzi obuvundlile ukuya kobude obuqondile (okungukuthi, ubude obuhlukaniswa ngobubanzi). Ubukhulu obubalulekile (i-CD) besekhethi buncane, bukhulu inani le-aspect ratio. Okusho ukuthi, uma kucatshangelwa inani le-aspect ratio engu-10 kanye nobubanzi obungu-10nm, ukuphakama kwembobo ebhoboziwe ngesikhathi sokuqoshwa kufanele kube ngu-100nm. Ngakho-ke, emikhiqizweni yesizukulwane esilandelayo edinga i-ultra-miniaturization (2D) noma ukuminyana okuphezulu (3D), amanani we-aspect ratio aphezulu kakhulu ayadingeka ukuze kuqinisekiswe ukuthi ama-cation angangena kufilimu engezansi ngesikhathi sokushumeka.
Ukuze kuzuzwe ubuchwepheshe be-ultra-miniaturization obunobukhulu obubalulekile obungaphansi kuka-10nm emikhiqizweni engu-2D, inani lesilinganiso se-capacitor sememori yokufinyelela engahleliwe (i-DRAM) kufanele igcinwe ngaphezu kuka-100. Ngokufanayo, inkumbulo ye-3D NAND flash nayo idinga amanani esilinganiso esiphezulu ukupakisha izendlalelo ezingama-256 noma ngaphezulu zezinhlaka zamaseli. Ngisho noma izimo ezidingekayo kwezinye izinqubo zihlangatshezwana nazo, imikhiqizo edingekayo ayikwazi ukukhiqizwa umainqubo etchingayikho ezingeni. Yingakho ubuchwepheshe be-etching buya ngokuya bubaluleke kakhulu.
2. Uhlolojikelele lwe-plasma etching
Umfanekiso 2. Ukunquma umthombo wegesi ye-plasma ngokohlobo lwefilimu
Uma kusetshenziswa ipayipi elingenalutho, i-diameter yepayipi iyancipha, kuba lula ukuthi kungene uketshezi, okubizwa ngokuthi i-capillary phenomenon. Kodwa-ke, uma imbobo (indawo evaliwe) kufanele ibhojwe endaweni evulekile, okokufaka koketshezi kuba nzima kakhulu. Ngakho-ke, njengoba usayizi obalulekile wesekethe wawungu-3um kuya ku-5um maphakathi nawo-1970, womile.etchingkancane kancane ithathe indawo ye-wet etching njenge-mainstream. Okusho ukuthi, nakuba i-ionized, kulula ukungena emigodini ejulile ngoba umthamo we-molecule eyodwa incane kunaleyo ye-organic polymer solution molecule.
Ngesikhathi sokufakwa kwe-plasma, ingaphakathi legumbi lokucutshungulwa elisetshenziselwa ukushumeka kufanele lilungiswe libe sesimweni sokushanela ngaphambi kokujova igesi yomthombo we-plasma efanele isendlalelo esifanele. Lapho unamathisela amafilimu e-solid oxide, amagesi anamandla asuselwa kukhabhoni fluoride kufanele asetshenziswe. Ku-silicon ebuthakathaka noma amafilimu ensimbi, amagesi omthombo we-plasma asekelwe ku-chlorine kufanele asetshenziswe.
Ngakho-ke, ungqimba lwesango kanye nongqimba olungaphansi lwe-silicon dioxide (SiO2) kufanele lufakwe kanjani?
Okokuqala, ungqimba lwesango, i-silicon kufanele isuswe kusetshenziswa i-plasma esekelwe ku-chlorine (i-silicon + chlorine) ene-polysilicon etching selectivity. Ngongqimba olungaphansi oluvikelayo, ifilimu ye-silicon dioxide kufanele ifakwe ezinyathelweni ezimbili kusetshenziswa igesi yomthombo we-plasma esekwe ku-carbon fluoride (i-silicon dioxide + carbon tetrafluoride) enokukhethwa okunamandla nokusebenza ngempumelelo.
3. Inqubo ye-ion etching esebenzayo (RIE noma i-physicochemical etching).
Umfanekiso 3. Izinzuzo zokushumeka kwe-ion esebenzayo (i-anisotropy kanye nezinga lokuqoshwa okuphezulu)
I-Plasma iqukethe kokubili ama-radicals mahhala we-isotropic nama-anisotropic cations, ngakho-ke yenza kanjani i-anisotropic etching?
Ukufakwa kwe-Plasma dry etching kwenziwa ikakhulukazi ngokushumeka kwe-ion esebenzayo (RIE, Reactive Ion Etching) noma izinhlelo zokusebenza ezisuselwe kule ndlela. Umnyombo wendlela ye-RIE uwukwenza buthaka amandla okubopha phakathi kwama-molecule aqondiwe kufilimu ngokuhlasela indawo yokuqopha ngama-anisotropic cations. Indawo ebuthaka imuncwa ama-radicals mahhala, ahlanganiswe nezinhlayiya ezakha ungqimba, aguqulwe abe yigesi (inhlanganisela eguquguqukayo) futhi akhululwe.
Nakuba ama-radicals amahhala enezici ze-isotropic, ama-molecule akha indawo engaphansi (amandla awo okubopha enziwa buthaka ukuhlasela kwama-cations) abanjwa kalula ngama-radicals mahhala futhi aguqulelwe abe yizinhlanganisela ezintsha kunezindonga eziseceleni ezinamandla okubopha okuqinile. Ngakho-ke, ukushona phansi kuba okujwayelekile. Izinhlayiya ezibanjiwe ziba igesi enama-radicals mahhala, akhishwa futhi akhishwe ebusweni ngaphansi kwesenzo se-vacuum.
Ngalesi sikhathi, ama-cations atholwe isenzo somzimba kanye nama-radicals mahhala atholwe isenzo samakhemikhali ahlanganiswa ukuze afakwe ngokomzimba namakhemikhali, futhi izinga lokucwiliswa (I-Etch Rate, i-degree of etching esikhathini esithile) lenyuka izikhathi ezingu-10. uma kuqhathaniswa nendaba ye-cationic etching noma i-free radical etching iyodwa. Le ndlela ayikwazi nje ukukhulisa izinga lokunamathisela kwe-anisotropic etching phansi, kodwa futhi ixazulule inkinga yezinsalela ze-polymer ngemva kokucwiliswa. Le ndlela ibizwa ngokuthi i-reactive ion etching (RIE). Isihluthulelo sempumelelo ye-RIE etching ukuthola igesi yomthombo we-plasma elungele ukushumeka ifilimu. Qaphela: I-Plasma etching i-RIE etching, futhi kokubili kungathathwa njengomqondo ofanayo.
4. I-Etch Rate kanye ne-Core Performance Index
Umfanekiso 4. I-Core Etch Performance Index ehlobene ne-Etch Rate
I-Etch rate isho ukujula kwefilimu okulindeleke ukuthi ifinyelelwe emzuzwini owodwa. Ngakho-ke kusho ukuthini ukuthi isilinganiso se-etch siyahlukahluka kusuka engxenyeni kuya kwesinye ku-wafer eyodwa?
Lokhu kusho ukuthi ukujula kwe-etch kuyahlukahluka kusuka engxenyeni kuya engxenyeni ku-wafer. Ngenxa yalesi sizathu, kubaluleke kakhulu ukusetha indawo yokugcina (EOP) lapho ukuqoshwa kufanele kume ngokucabangela isilinganiso esimaphakathi se-etch nokujula kwe-etch. Ngisho noma i-EOP isethiwe, zisekhona ezinye izindawo lapho ukujula kwe-etch kujule khona (kuqoshwe ngokweqile) noma kuncane kakhulu (okubhalwe ngaphansi) kunalokho obekuhleliwe ekuqaleni. Kodwa-ke, i-under-etching idala umonakalo omkhulu kunokukhipha kakhulu ngesikhathi sokucwiliswa. Ngoba esimweni sokucwiliswa ngaphansi, ingxenye engagxiliwe kancane izovimbela izinqubo ezilandelayo ezifana nokufakwa kwe-ion.
Ngaleso sikhathi, ukukhetha (kukalwa nge-etch rate) kuyinkomba yokusebenza eyinhloko yenqubo yokuqopha. Izinga lokulinganisa lisekelwe ekuqhathanisweni kwezinga le-etch lesendlalelo semaski (ifilimu ye-photoresist, ifilimu ye-oxide, ifilimu ye-silicon nitride, njll.) kanye nongqimba oluqondiwe. Lokhu kusho ukuthi uma ukukhetha kuphezulu, ungqimba oluqondiwe luqoshwa ngokushesha. Uma izinga le-miniaturization liphakeme, imfuneko yokukhetha iphezulu kakhulu ukuqinisekisa ukuthi amaphethini amahle angethulwa kahle. Njengoba isiqondiso se-etching siqondile, ukukhetha kwe-cationic etching kuphansi, kuyilapho ukukhethwa kwe-radical etching kuphezulu, okuthuthukisa ukukhetha kwe-RIE.
5. Etching inqubo
Umfanekiso 5. Inqubo yokufaka
Okokuqala, i-wafer ifakwa esithandweni se-oxidation esinezinga lokushisa eligcinwe phakathi kuka-800 no-1000 ℃, bese kwakheka ifilimu ye-silicon dioxide (SiO2) enezakhiwo eziphakeme zokushisa phezu kwewafa ngendlela eyomile. Okulandelayo, inqubo yokubeka ifakwa ukuze yakhe ungqimba lwe-silicon noma ungqimba olubambayo kufilimu ye-oxide nge-chemical vapor deposition (CVD)/physical vapor deposition (PVD). Uma kwakhiwa ungqimba lwe-silicon, inqubo yokusabalalisa ukungcola ingenziwa ukuze kwandiswe ukuqhutshwa uma kunesidingo. Phakathi nenqubo yokusabalalisa ukungcola, ukungcola okuningi kuvame ukungezwa ngokuphindaphindiwe.
Ngalesi sikhathi, ungqimba lwe-insulating kanye nongqimba lwe-polysilicon kufanele kuhlanganiswe ukuze kufakwe. Okokuqala, i-photoresist isetshenziswa. Kamuva, imaskhi ifakwa kwifilimu ye-photoresist futhi ukuchayeka okumanzi kwenziwa ngokucwiliswa ukuze kugxilwe iphethini oyifunayo (engabonakali ngeso lenyama) kufilimu ye-photoresist. Uma uhlaka lwephethini lwembulwa ngokuthuthuka, i-photoresist endaweni ezwelayo iyasuswa. Bese, i-wafer ecutshungulwa yinqubo ye-photolithography idluliselwa kunqubo yokunamathisela ukuze kufakwe okomile.
I-Dry etching yenziwa ikakhulukazi yi-reactive ion etching (RIE), lapho ukushumeka kuphindwa khona ngokuyinhloko ngokufaka esikhundleni segesi yomthombo efanele ifilimu ngayinye. Kokubili i-etching eyomile kanye ne-etching emanzi ihlose ukukhulisa i-aspect ratio (inani elingu-A/R) lokunamathisela. Ukwengeza, ukuhlanza okuvamile kuyadingeka ukuze kukhishwe i-polymer eqoqwe phansi komgodi (igebe elakhiwe ngokuqopha). Iphuzu elibalulekile liwukuthi zonke izinto eziguquguqukayo (njengezinto, igesi yomthombo, isikhathi, ifomu kanye nokulandelana) kufanele kulungiswe ngokuphilayo ukuze kuqinisekiswe ukuthi isisombululo sokuhlanza noma igesi yomthombo we-plasma ingageleza phansi phansi komsele. Ushintsho oluncane kokuguquguqukayo ludinga ukubalwa kabusha kokunye okuguquguqukayo, futhi le nqubo yokubala kabusha iyaphindwa ize ihlangabezane nenjongo yesigaba ngasinye. Muva nje, izendlalelo ze-monoatomic ezifana nezendlalelo ze-atomic layer deposition (ALD) ziye zaba zizacile futhi zaba lukhuni. Ngakho-ke, ubuchwepheshe be-etching buqhubekela phambili ekusetshenzisweni kwamazinga okushisa aphansi nezingcindezi. Inqubo yokuqopha ihlose ukulawula i-critical dimension (CD) ukuze ikhiqize amaphethini amahle futhi iqinisekise ukuthi izinkinga ezibangelwa inqubo yokunamathisela ziyagwenywa, ikakhulukazi ukucwiliswa kancane kanye nezinkinga ezihlobene nokususwa kwezinsalela. Lezi zihloko ezimbili ezingenhla ezimayelana ne-etching zihlose ukunikeza abafundi ukuqonda injongo yenqubo yokubhala, izithiyo zokufeza lezi zinhloso ezingenhla, kanye nezinkomba zokusebenza ezisetshenziselwa ukunqoba lezi zithiyo.
Isikhathi sokuthumela: Sep-10-2024