Farkon rigar etching yana haɓaka haɓakar tsarin tsaftacewa ko toka. A yau, busassun etching ta amfani da plasma ya zama al'adaetching tsari. Plasma ya ƙunshi electrons, cations da radicals. Ƙarfin da ake amfani da shi a cikin plasma yana haifar da fitar da mafi ƙarancin electrons na iskar gas a cikin tsaka-tsakin yanayi, ta yadda za a canza waɗannan electrons zuwa cations.
Bugu da kari, ana iya cire atom ɗin da ke cikin ƙwayoyin cuta ta hanyar amfani da makamashi don samar da tsattsauran ra'ayi na lantarki. Dry etching yana amfani da cations da radicals waɗanda suka haɗa da plasma, inda cations sune anisotropic (wanda ya dace da etching a wani wuri) kuma masu tsattsauran ra'ayi suna isotropic (dace da etching a kowane bangare). Adadin masu tsattsauran ra'ayi ya fi yawan cations girma. A wannan yanayin, bushe etching ya zama isotropic kamar rigar etching.
Duk da haka, anisotropic etching na bushe etching ne ya sa ultra-miniaturized da'irori yiwu. Menene dalilin hakan? Bugu da kari, saurin etching na cations da radicals yana da sannu a hankali. Don haka ta yaya za mu iya amfani da hanyoyin etching na plasma don samar da yawa ta fuskar wannan gazawar?
1. Girman Halaye (A/R)
Hoto 1. Ma'anar rabon al'amari da tasirin ci gaban fasaha akansa
Girman Halaye shine rabon faɗin kwance zuwa tsayin tsaye (watau tsayin da aka raba da faɗi). Karamin mahimmin girma (CD) na kewaye, mafi girman ƙimar rabon al'amari. Wato idan aka yi la'akari da ƙimar ƙimar 10 da faɗin 10nm, tsayin ramin da aka haƙa yayin aikin etching yakamata ya zama 100nm. Don haka, don samfuran ƙarni na gaba waɗanda ke buƙatar ultra-miniaturization (2D) ko babban yawa (3D), ana buƙatar ƙimar rabo mai girman gaske don tabbatar da cewa cations na iya shiga cikin fim ɗin ƙasa yayin etching.
Don cimma fasahar ƙaramin ƙarami tare da mahimmin girman ƙasa da 10nm a cikin samfuran 2D, ƙimar ƙimar ƙimar ƙarfin bazuwar damar ƙwaƙwalwar ajiya (DRAM) yakamata a kiyaye sama da 100. Hakazalika, ƙwaƙwalwar filasha ta 3D NAND kuma tana buƙatar ƙimar rabo mafi girma. don tara yadudduka 256 ko fiye na yadudduka stacking cell. Ko da an cika sharuɗɗan da ake buƙata don wasu matakai, samfuran da ake buƙata ba za a iya samar da su ba idanetching tsaribai kai matsayin ba. Wannan shine dalilin da ya sa fasahar etching ke ƙara zama mahimmanci.
2. Bayani akan etching plasma
Hoto 2. Ƙayyadaddun iskar gas ɗin plasma bisa ga nau'in fim
Lokacin da aka yi amfani da bututu mai zurfi, ƙananan diamita na bututu, da sauƙi don shigar da ruwa, shine abin da ake kira capillary phenomenon. Duk da haka, idan za a haƙa rami (ƙarshen rufe) a cikin wurin da aka fallasa, shigar da ruwa ya zama mai wahala. Saboda haka, tun da mahimmancin girman da'irar ya kasance 3um zuwa 5um a tsakiyar 1970s, bushe.etchingsannu a hankali ya maye gurbin rigar etching a matsayin al'ada. Wato, ko da yake ionized, yana da sauƙi don kutsawa cikin zurfin ramuka saboda girman ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar ƙwayar cuta ta polymer.
Yayin etching na plasma, ya kamata a daidaita cikin ɗakin sarrafawa da aka yi amfani da shi don etching zuwa yanayin da ba shi da amfani kafin allurar tushen iskar plasma wanda ya dace da abin da ya dace. Lokacin da aka fitar da fina-finai masu ƙarfi, ya kamata a yi amfani da iskar gas mai tushe mai ƙarfi na carbon fluoride. Don ƙarancin silica ko fina-finan ƙarfe, yakamata a yi amfani da iskar gas na tushen chlorine.
Don haka, ta yaya ya kamata a cire Layer na ƙofar kofa da silicon dioxide (SiO2) mai rufewa Layer?
Na farko, don murfin ƙofar, ya kamata a cire silicon ta amfani da plasma na tushen chlorine (silicon + chlorine) tare da zaɓin zaɓi na etching na polysilicon. Don kasan insulating Layer, fim ɗin silicon dioxide ya kamata a liƙa a cikin matakai biyu ta amfani da iskar gas mai tushen iskar carbon fluoride (silicon dioxide + carbon tetrafluoride) tare da zaɓi mai ƙarfi da inganci.
3. Reactive ion etching (RIE ko physicochemical etching) tsari
Hoto 3. Amfanin ion etching reactive (anisotropy da babban etching rate)
Plasma ya ƙunshi duka nau'ikan radicals na isotropic da cations anisotropic, don haka ta yaya yake yin etching anisotropic?
Plasma bushe etching ana yin shi ne ta hanyar reactive ion etching (RIE, Reactive Ion Etching) ko aikace-aikace dangane da wannan hanyar. Tushen hanyar RIE ita ce raunana ƙarfin dauri tsakanin ƙwayoyin da aka yi niyya a cikin fim ɗin ta hanyar kai hari a yankin etching tare da cations anisotropic. Wurin da aka raunana yana shafewa ta hanyar radicals kyauta, hade tare da barbashi da suka hada da Layer, sun juya zuwa gas (wani fili mai canzawa) kuma a sake shi.
Ko da yake free radicals suna da isotropic halaye, kwayoyin da ke hade da kasa surface (wanda daurin dauri da aka raunana da harin cations) an fi sauƙi kama da free radicals da kuma canza zuwa sabon mahadi fiye da gefen bango da karfi dauri da karfi. Don haka, etching zuwa ƙasa ya zama babban al'ada. Kwayoyin da aka kama sun zama iskar gas tare da radicals masu kyauta, waɗanda aka desorbed kuma an sake su daga saman a ƙarƙashin aikin vacuum.
A wannan lokacin, cations da aka samu ta hanyar aikin jiki da kuma free radicals da aka samu ta hanyar sinadarai ana haɗa su don fitar da jiki da sinadarai, kuma yawan etching (Etch Rate, digiri na etching a cikin wani lokaci) yana ƙaruwa da sau 10. idan aka kwatanta da yanayin cationic etching ko free radical etching kadai. Wannan hanya ba za ta iya kawai ƙara yawan etching na anisotropic ƙasa etching ba, amma kuma magance matsalar ragowar polymer bayan etching. Ana kiran wannan hanyar reactive ion etching (RIE). Makullin samun nasarar RIE etching shine samun iskar gas ɗin plasma wanda ya dace da etching fim ɗin. Lura: Plasma etching shine RIE etching, kuma ana iya ɗaukar su biyu azaman ra'ayi ɗaya.
4. Etch Rate da Core Performance Index
Hoto 4. Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwararren Ƙwaƙwalwa na Ƙaƙwalwa na Ƙimar Ƙirar Ƙimar Ƙirar Ƙimar Ƙirar Ƙimar Ƙirar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙirar Ƙimar Ƙimar Ƙimar Ƙirar Ƙimar Ƙimar Ƙirar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙimar Ƙi) mai dangantaka da Ƙimar Ƙimar
Etch rate yana nufin zurfin fim ɗin da ake sa ran a kai a cikin minti ɗaya. Don haka menene ma'anar ƙimar etch ya bambanta daga sashi zuwa sashi akan wafer guda?
Wannan yana nufin cewa zurfin etch ya bambanta daga sashi zuwa sashi akan wafer. Saboda wannan dalili, yana da matukar mahimmanci a saita ƙarshen ƙarshen (EOP) inda yakamata a daina yin etching ta hanyar la'akari da matsakaicin ƙimar etch da zurfin ƙyalli. Ko da an saita EOP, har yanzu akwai wasu wuraren da zurfin etch ya fi zurfi (fiye da ƙima) ko shallower (ƙasa-ƙasa) fiye da yadda aka tsara tun farko. Duk da haka, rashin etching yana haifar da lahani fiye da yawan zubar da ciki yayin etching. Domin idan aka yi la’akari da ƙayyadaddun ƙayyadaddun ƙayyadaddun tsarin, ɓangaren da ba a haɗa shi ba zai kawo cikas ga matakai na gaba kamar dasa ion.
A halin yanzu, zaɓi (wanda aka auna ta ƙimar etch) shine maɓalli mai nuna alamar aiki na tsarin etching. Ma'aunin ma'auni ya dogara ne akan kwatancen ƙimar etch na abin rufe fuska (fim ɗin hoto, fim ɗin oxide, fim ɗin silicon nitride, da sauransu) da maƙasudin manufa. Wannan yana nufin cewa mafi girman zaɓin, mafi saurin abin da aka yi niyya ana ƙirƙira shi. Mafi girman matakin miniaturization, mafi girman zaɓin zaɓi shine tabbatar da cewa za a iya gabatar da kyawawan alamu daidai. Tun da jagorancin etching ya kasance madaidaiciya, zaɓi na cationic etching yana da ƙasa, yayin da zaɓi na radical etching yana da girma, wanda ke inganta zaɓin RIE.
5. Tsarin Etching
Hoto 5. Tsarin Etching
Da farko, ana sanya wafer a cikin tanderun iskar shaka tare da zafin jiki tsakanin 800 da 1000 ℃, sa'an nan kuma an kafa fim ɗin silicon dioxide (SiO2) tare da manyan kaddarorin rufewa a saman wafer ta hanyar bushewa. Bayan haka, ana shigar da tsarin ƙaddamarwa don samar da siliki Layer ko wani nau'i mai ɗaukar hoto akan fim ɗin oxide ta hanyar shigar da tururin sinadarai (CVD)/haɓaka tururin jiki (PVD). Idan an kafa Layer silicon, ana iya aiwatar da tsarin watsawa na ƙazanta don ƙara haɓaka aiki idan ya cancanta. A lokacin aikin yada ƙazanta, ana ƙara ƙazanta da yawa akai-akai.
A wannan lokacin, ya kamata a haɗa Layer na insulating da polysilicon Layer don etching. Na farko, ana amfani da photoresist. Bayan haka, an sanya abin rufe fuska a kan fim ɗin photoresist kuma ana yin fallasa rigar ta hanyar nutsewa don buga tsarin da ake so (wanda ba a gani ga ido tsirara) akan fim ɗin hoto. Lokacin da ƙirar ƙirar ta bayyana ta haɓakawa, ana cire mai ɗaukar hoto a cikin yanki mai ɗaukar hoto. Sa'an nan, wafer da aka sarrafa ta hanyar photolithography an canza shi zuwa tsarin etching don bushe etching.
Dry etching ana yin shi ne ta hanyar reactive ion etching (RIE), wanda ake maimaita etching musamman ta hanyar maye gurbin iskar gas mai dacewa da kowane fim. Dukansu busassun etching da rigar etching suna nufin ƙara ƙimar yanayin (ƙimar A/R) na etching. Bugu da ƙari, ana buƙatar tsaftacewa na yau da kullum don cire polymer da aka tara a kasan ramin (rabin da aka kafa ta hanyar etching). Muhimmin batu shine cewa duk masu canji (kamar kayan, iskar gas, lokaci, tsari da jerin) yakamata a daidaita su ta zahiri don tabbatar da cewa maganin tsaftacewa ko iskar gas na plasma na iya gudana zuwa kasan ramin. Canji kaɗan a cikin ma'auni yana buƙatar sake ƙididdige wasu masu canji, kuma ana maimaita wannan tsarin ƙididdigewa har sai ya dace da manufar kowane mataki. Kwanan nan, yadudduka na monoatomic irin su atomic Layer deposition (ALD) ya zama sirara da ƙarfi. Saboda haka, fasahar etching tana motsawa zuwa amfani da ƙananan yanayin zafi da matsa lamba. Tsarin etching yana nufin sarrafa girman mahimmanci (CD) don samar da kyakkyawan tsari da kuma tabbatar da cewa an kauce wa matsalolin da tsarin etching ke haifarwa, musamman ma ƙarancin etching da matsalolin da suka shafi cirewa. Kasidu biyun da ke sama kan etching suna da nufin baiwa masu karatu fahimtar makasudin tsarin etching, abubuwan da ke kawo cikas ga cimma manufofin da ke sama, da kuma alamomin aikin da ake amfani da su don shawo kan irin wadannan matsalolin.
Lokacin aikawa: Satumba-10-2024