Ukucheba okumanzi kwasekuqaleni kwakhuthaza ukuthuthukiswa kwezinqubo zokuhlanza noma zokulahla umlotha. Namuhla, ukucheba okomile kusetshenziswa i-plasma sekuyinto evamileinqubo yokuqophaI-Plasma yakhiwa ama-electron, ama-cation kanye nama-radical. Amandla asetshenziswa ku-plasma abangela ukuthi ama-electron angaphandle kwegesi yomthombo asesimweni sokungathathi hlangothi asuswe, ngaleyo ndlela aguqule la ma-electron abe ama-cation.
Ngaphezu kwalokho, ama-athomu angaphelele kuma-molecule angasuswa ngokusebenzisa amandla ukwakha ama-radical angathathi hlangothi kagesi. Ukugoba okomile kusebenzisa ama-cation nama-radical akha i-plasma, lapho ama-cation e-anisotropic (afanelekela ukugoba ohlangothini oluthile) kanti ama-radical ayi-isotropic (afanelekela ukugoba kuzo zonke izinhlangothi). Inani lama-radical likhulu kakhulu kunenani lama-cation. Kulesi simo, ukugoba okomile kufanele kube yi-isotropic njengokugoba okumanzi.
Kodwa-ke, ukuchoma okune-anisotropic kokuchoma okomile okwenza kube nokwenzeka amasekethe amancane kakhulu. Iyini imbangela yalokhu? Ngaphezu kwalokho, ijubane lokuchoma lama-cation nama-radical lihamba kancane kakhulu. Ngakho-ke singazisebenzisa kanjani izindlela zokuchoma nge-plasma ekukhiqizeni ngobuningi lapho sibhekene nalokhu kusilela?
1. Isilinganiso Sokubukeka (A/R)
Isithombe 1. Umqondo wesilinganiso sesici kanye nomthelela wentuthuko yezobuchwepheshe kuwo
Isilinganiso Sokubheka yisilinganiso sobubanzi obuvundlile nokuphakama okuqondile (okungukuthi, ukuphakama okuhlukaniswe ububanzi). Uma ubukhulu obubalulekile (i-CD) besekethe buncane, inani lesilinganiso sokubheka likhudlwana. Okusho ukuthi, uma sicabanga ukuthi inani lesilinganiso sokubheka elingu-10 nobubanzi obungu-10nm, ukuphakama komgodi obholiwe ngesikhathi senqubo yokubheka kufanele kube ngu-100nm. Ngakho-ke, emikhiqizweni yesizukulwane esilandelayo edinga i-ultra-miniaturization (2D) noma i-high density (3D), amanani aphezulu kakhulu okubheka aspect ratio ayadingeka ukuqinisekisa ukuthi ama-cation angangena efilimini engezansi ngesikhathi sokubheka.
Ukuze kufezwe ubuchwepheshe be-ultra-miniaturization obunobukhulu obubalulekile obungaphansi kuka-10nm emikhiqizweni ye-2D, inani le-capacitor aspect ratio le-dynamic random access memory (DRAM) kufanele ligcinwe lingaphezu kuka-100. Ngokufanayo, i-3D NAND flash memory idinga futhi amanani aphezulu e-aspect ratio ukuze kuhlanganiswe izendlalelo ezingu-256 noma ngaphezulu zezendlalelo ze-cell stacking. Ngisho noma izimo ezidingekayo kwezinye izinqubo zihlangatshezwana, imikhiqizo edingekayo ayikwazi ukukhiqizwa umainqubo yokuqophaakusesezingeni elifanele. Yingakho ubuchwepheshe bokuqopha buqala ukuba yinto ebaluleke kakhulu.
2. Ukubuka konke kokuqopha nge-plasma
Umfanekiso 2. Ukunquma umthombo wegesi we-plasma ngokohlobo lwefilimu
Uma kusetshenziswa ipayipi elingenalutho, uma ububanzi bepayipi buncipha, kuba lula ukuthi uketshezi lungene, okuyi-capillary phenomenon. Kodwa-ke, uma kuzobholwa imbobo (ukuphela okuvaliwe) endaweni eveziwe, ukufakwa koketshezi kuba nzima kakhulu. Ngakho-ke, njengoba usayizi obalulekile wesekethe wawungu-3um kuya ku-5um maphakathi nawo-1970, owomileukuqophakancane kancane ithathe indawo yokucwilisa okumanzi njengento evamile. Lokho kusho ukuthi, nakuba i-ionized, kulula ukungena emigodini ejulile ngoba umthamo we-molecule eyodwa mncane kunowe-molecule yesisombululo se-polymer yemvelo.
Ngesikhathi sokusika i-plasma, ingaphakathi legumbi lokucubungula elisetshenziselwa ukusika kufanele lilungiswe libe yisimo se-vacuum ngaphambi kokufaka igesi yomthombo we-plasma efanele ungqimba olufanele. Lapho kusika amafilimu e-solid oxide, kufanele kusetshenziswe amagesi omthombo aqinile asekelwe ku-carbon fluoride. Kumafilimu e-silicon noma ensimbi abuthakathaka, kufanele kusetshenziswe amagesi omthombo we-plasma asekelwe ku-chlorine.
Ngakho-ke, ungqimba lwesango kanye nongqimba olungaphansi lwe-silicon dioxide (SiO2) insulating kufanele luqoshwe kanjani?
Okokuqala, ngesendlalelo sesango, i-silicon kufanele isuswe kusetshenziswa i-plasma esekelwe ku-chlorine (i-silicon + i-chlorine) enokukhetha ukugoba kwe-polysilicon. Ngesendlalelo sokuvikela esingezansi, ifilimu ye-silicon dioxide kufanele igobe ngezinyathelo ezimbili kusetshenziswa igesi yomthombo we-plasma esekelwe ku-carbon fluoride (i-silicon dioxide + i-carbon tetrafluoride) enokukhetha okunamandla nokuphumelelayo kokugoba.
3. Inqubo yokuchoma ama-ion asebenzayo (i-RIE noma i-physicochemical etching)
Umfanekiso 3. Izinzuzo zokuchoboza ama-ion asebenzayo (i-anisotropy kanye nesilinganiso esiphezulu sokuchoboza)
I-plasma iqukethe kokubili ama-free radicals e-isotropic kanye nama-cations e-anisotropic, ngakho-ke yenza kanjani i-anisotropic etching?
Ukuchoma okomile kwe-plasma kwenziwa kakhulu ngokuchoma kwe-ion ephendulayo (RIE, Reactive Ion Etching) noma izinhlelo zokusebenza ezisekelwe kule ndlela. Ingqikithi yendlela ye-RIE ukwenza buthaka amandla okubopha phakathi kwama-molecule aqondiwe efilimini ngokuhlasela indawo yokuchoma ngama-cation anisotropic. Indawo ebuthakathaka imuncwa ama-free radicals, ahlanganiswe nezinhlayiya ezakha ungqimba, aguqulwe abe yigesi (i-compound eguquguqukayo) bese ekhishwa.
Nakuba ama-free radicals enezici ze-isotropic, ama-molecule akha ubuso obungaphansi (amandla awo okubopha abuthakathaka ukuhlaselwa kwama-cations) abanjwa kalula ngama-free radicals futhi aguqulwe abe ama-compound amasha kunezindonga eziseceleni ezinamandla okubopha aqinile. Ngakho-ke, ukugoba phansi kuba yinto eyinhloko. Izinhlayiya ezibanjiwe ziba yigesi ene-free radicals, ezikhishwa futhi zikhishwe ebusweni ngaphansi kwesenzo se-vacuum.
Ngalesi sikhathi, ama-cation atholakala ngesenzo somzimba kanye nama-free radical atholakala ngesenzo samakhemikhali ahlanganiswa ukuze kuqoshwe ngokomzimba nangokwekhemikhali, futhi izinga lokuqoshwa (Izinga Lokuqoshwa, izinga lokuqoshwa esikhathini esithile) landa ngokuphindwe kayishumi uma kuqhathaniswa necala lokuqoshwa kwe-cationic noma ukuqoshwa kwe-free radical kuphela. Le ndlela ayikwazi nje ukwandisa izinga lokuqoshwa kokuqoshwa kwe-anisotropic downward, kodwa futhi ixazulule inkinga ye-polymer residue ngemva kokuqoshwa. Le ndlela ibizwa ngokuthi i-reactive ion etching (RIE). Isihluthulelo sempumelelo yokuqoshwa kwe-RIE ukuthola igesi yomthombo we-plasma efanele ukuqoshwa kwefilimu. Qaphela: Ukuqoshwa kwe-plasma kuyi-RIE etching, futhi lokhu kokubili kungabhekwa njengomqondo ofanayo.
4. Izinga Lokuqopha kanye Nenkomba Yokusebenza Okuyinhloko
Umfanekiso 4. Inkomba Yokusebenza Kwe-Core Etch ehlobene Nezinga Le-Etch
Izinga lokugqwala libhekisela ekujuleni kwefilimu okulindeleke ukuthi kufinyelelwe kuyo ngomzuzu owodwa. Ngakho-ke kusho ukuthini ukuthi izinga lokugqwala liyahlukahluka kusuka engxenyeni kuya engxenyeni ku-wafer eyodwa?
Lokhu kusho ukuthi ukujula kwe-etch kuyahlukahluka kusukela engxenyeni kuya engxenyeni ku-wafer. Ngenxa yalesi sizathu, kubaluleke kakhulu ukusetha iphuzu lokugcina (i-EOP) lapho ukugcaba kufanele kume khona ngokucabangela izinga elijwayelekile lokugcaba kanye nokujula kwe-etch. Ngisho noma i-EOP isethiwe, kusenezindawo ezithile lapho ukujula kwe-etch kujule khona (kugcaba ngokweqile) noma kuncane kakhulu (kugcaba kancane) kunalokho obekuhleliwe ekuqaleni. Kodwa-ke, ukugcaba kancane kubangela umonakalo omkhulu kunokugcaba ngokweqile ngesikhathi sokugcaba. Ngoba esimweni sokugcaba kancane, ingxenye engagcaba kancane izophazamisa izinqubo ezilandelayo njengokufakelwa kwe-ion.
Okwamanje, ukukhetha (okulinganiswe ngesilinganiso se-etch) kuyisibonakaliso esibalulekile sokusebenza kwenqubo yokuqopha. Izinga lokulinganisa lisekelwe ekuqhathanisweni kwesilinganiso se-etch sesendlalelo semaski (ifilimu ye-photoresist, ifilimu ye-oxide, ifilimu ye-silicon nitride, njll.) kanye nesendlalelo esiqondiwe. Lokhu kusho ukuthi lapho ukukhetha kuphakeme, kulapho ungqimba oluqondiwe luqopha ngokushesha khona. Lapho izinga le-miniaturization liphezulu, kulapho isidingo sokukhetha siphezulu khona ukuqinisekisa ukuthi amaphethini amahle angavezwa kahle. Njengoba isiqondiso sokuqopha siqondile, ukukhetha kokuqopha kwe-cationic kuphansi, kuyilapho ukukhetha kokuqopha okunamandla kuphezulu, okuthuthukisa ukukhetha kwe-RIE.
5. Inqubo yokuqopha
Umfanekiso 5. Inqubo yokuqopha
Okokuqala, i-wafer ifakwa esithandweni se-oxidation lapho izinga lokushisa ligcinwa phakathi kuka-800 no-1000℃, bese kwakheka ifilimu ye-silicon dioxide (SiO2) enezakhiwo eziphezulu zokushisa ebusweni be-wafer ngendlela eyomile. Okulandelayo, inqubo yokufaka ifakwa ukuze kwakhiwe ungqimba lwe-silicon noma ungqimba oluqhubayo kufilimu ye-oxide nge-chemical vapor deposition (CVD)/physical vapor deposition (PVD). Uma kwakhiwa ungqimba lwe-silicon, inqubo yokusabalalisa ukungcola ingenziwa ukuze kwandiswe ukuhanjiswa uma kudingeka. Ngesikhathi senqubo yokusabalalisa ukungcola, ukungcola okuningi kuvame ukungezwa ngokuphindaphindiwe.
Ngalesi sikhathi, ungqimba oluvikela ukushisa kanye nongqimba lwe-polysilicon kufanele kuhlanganiswe ukuze kuqoshwe. Okokuqala, kusetshenziswa i-photoresist. Ngemva kwalokho, kufakwa imaski efilimini ye-photoresist bese kuvezwa ukumanzi ngokucwiliswa ukuze kufakwe iphethini oyifunayo (engabonakali emehlweni) efilimini ye-photoresist. Lapho uhlaka lwephethini lwembulwa yintuthuko, i-photoresist endaweni ezwela ukukhanya iyasuswa. Ngemuva kwalokho, i-wafer ecutshungulwa yinqubo ye-photolithography idluliselwa enqubweni yokuqoshwa ukuze kuqoshwe okomile.
Ukugcaba okomile kwenziwa kakhulu ngokugcaba kwe-ion okusebenzayo (RIE), lapho ukugcaba kuphindaphindwa khona ikakhulukazi ngokufaka esikhundleni segesi yomthombo efanele ifilimu ngayinye. Kokubili ukugcaba okomile kanye nokugcaba okumanzi kuhlose ukwandisa isilinganiso se-aspect (inani le-A/R) lokugcaba. Ngaphezu kwalokho, ukuhlanza okuvamile kuyadingeka ukuze kususwe i-polymer eqoqwe phansi komgodi (isikhala esakhiwe ngokugcaba). Iphuzu elibalulekile ukuthi zonke izinto eziguquguqukayo (ezifana nezinto zokwakha, igesi yomthombo, isikhathi, ifomu kanye nokulandelana) kufanele zilungiswe ngokwemvelo ukuqinisekisa ukuthi isisombululo sokuhlanza noma igesi yomthombo we-plasma ingageleza iye phansi komsele. Ushintsho oluncane kuguquko ludinga ukubalwa kabusha kwezinye izinto eziguquguqukayo, futhi le nqubo yokubala kabusha iphindaphindwa kuze kube yilapho ihlangabezana nenhloso yesigaba ngasinye. Muva nje, izendlalelo ze-monoatomic ezifana nezendlalelo ze-atomic layer deposition (ALD) ziye zaba zincane futhi zaba nzima. Ngakho-ke, ubuchwepheshe bokugcaba buqhubekela ekusebenziseni amazinga okushisa aphansi kanye nokucindezela. Inqubo yokugcaba ihlose ukulawula ubukhulu obubalulekile (CD) ukukhiqiza amaphethini amahle nokuqinisekisa ukuthi izinkinga ezibangelwa inqubo yokugcaba ziyagwenywa, ikakhulukazi ukugcaba okungaphelele nezinkinga ezihlobene nokususwa kwezinsalela. Izihloko ezimbili ezingenhla mayelana nokusika zihlose ukunikeza abafundi ukuqonda injongo yenqubo yokusika, izithiyo zokufeza imigomo engenhla, kanye nezinkomba zokusebenza ezisetshenziswa ukunqoba izithiyo ezinjalo.
Isikhathi sokuthunyelwe: Septhemba-10-2024