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 ngokufaka i-etching). 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) zibe 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