Sassaka da ruwa da wuri ya ƙarfafa ci gaban hanyoyin tsaftacewa ko toka. A yau, sassaka busasshiyar hanya ta amfani da plasma ta zama ruwan dare gama garitsarin ƙwanƙwasaPlasma ta ƙunshi electrons, cations da radicals. Ƙarfin da aka yi amfani da shi a cikin plasma yana sa electrons na waje na iskar gas ɗin da ke cikin yanayi mai tsaka-tsaki su ɓace, ta haka ne za a mayar da waɗannan electrons zuwa cations.
Bugu da ƙari, ana iya cire ƙwayoyin halitta marasa kyau a cikin ƙwayoyin halitta ta hanyar amfani da makamashi don samar da ƙwayoyin halitta marasa tsaka tsaki a cikin wutar lantarki. Busasshen etching yana amfani da cations da radicals waɗanda suka samar da plasma, inda cations suke da anisotropic (sun dace da etching a wani takamaiman alkibla) kuma radicals suna da isotropic (sun dace da etching a kowane bangare). Adadin radicals ya fi yawan cations girma. A wannan yanayin, busasshen etching ya kamata ya zama isotropic kamar etching mai laushi.
Duk da haka, anisotropic etching na busasshen etching ne ke sa da'irori masu ƙarancin ƙananan yawa su yiwu. Menene dalilin haka? Bugu da ƙari, saurin etching na cations da radicals yana da jinkiri sosai. To ta yaya za mu iya amfani da hanyoyin etching na plasma don samar da taro a gaban wannan gazawar?
1. Rabon Al'amari (A/R)
Siffa ta 1. Ma'anar rabon al'amari da tasirin ci gaban fasaha a kansa
Rabon Aspect shine rabon faɗin kwance zuwa tsayin tsaye (watau, tsayin da aka raba da faɗi). Mafi ƙarancin girma mai mahimmanci (CD) na da'irar, mafi girman ƙimar rabon al'amari. Wato, idan aka ɗauka cewa ƙimar rabon al'amari ta 10 da faɗin 10nm, tsayin ramin da aka haƙa a lokacin aikin etching ya kamata ya zama 100nm. Saboda haka, ga samfuran tsara na gaba waɗanda ke buƙatar ƙarancin girman (2D) ko babban yawa (3D), ana buƙatar ƙimar rabon al'amari mai girma sosai don tabbatar da cewa cations na iya shiga cikin fim ɗin ƙasa yayin etching.
Domin cimma fasahar rage girman bayanai ta ultra-miniaturization tare da ma'aunin ƙasa da 10nm a cikin samfuran 2D, ya kamata a kiyaye ƙimar rabon capacitor na ƙwaƙwalwar damar shiga bazuwar (DRAM) sama da 100. Hakazalika, ƙwaƙwalwar walƙiya ta 3D NAND kuma tana buƙatar ƙimar rabo mafi girma don tara layuka 256 ko fiye na layukan tara tantanin halitta. Ko da an cika sharuɗɗan da ake buƙata don wasu hanyoyin, ba za a iya samar da samfuran da ake buƙata ba idantsarin ƙwanƙwasabai kai matsayin da aka saba ba. Shi ya sa fasahar yin zane-zane ke ƙara zama mai mahimmanci.
2. Bayani game da ƙwanƙwasa jini
Siffa ta 2. Ƙayyade iskar gas ta plasma bisa ga nau'in fim
Idan aka yi amfani da bututu mai rami, idan diamita na bututun ya yi ƙanƙanta, to ruwa zai shiga cikin sauƙi, wanda ake kira abin da ake kira capillary event. Duk da haka, idan za a haƙa rami (ƙarshen rufe) a yankin da aka fallasa, shigar da ruwan zai yi wahala. Saboda haka, tunda girman da'irar ya kasance daga 3um zuwa 5um a tsakiyar shekarun 1970, bushewa.ƙeraa hankali ya maye gurbin etching ɗin da aka yi da ruwa a matsayin babban abu. Wato, duk da cewa an yi shi da ion, yana da sauƙi a shiga cikin ramuka masu zurfi saboda girman kwayar halitta ɗaya ya fi ƙanƙanta fiye da kwayar halittar polymer mai narkewa ta halitta.
A lokacin da ake yin fenti a cikin plasma, ya kamata a daidaita cikin ɗakin sarrafa da ake amfani da shi don yin fenti zuwa yanayin injin kafin a yi allurar iskar gas ɗin da ta dace da matakin da ya dace. Lokacin da ake yin fenti a cikin fim ɗin oxide mai ƙarfi, ya kamata a yi amfani da iskar gas mai ƙarfi da ke tushen carbon fluoride. Ga fina-finan silicon ko ƙarfe masu rauni, ya kamata a yi amfani da iskar gas mai tushen plasma mai tushen chlorine.
To, ta yaya ya kamata a yi amfani da layin ƙofar da kuma layin silicon dioxide (SiO2) mai rufi a ƙasa?
Da farko, don layin ƙofar, ya kamata a cire silicon ta amfani da plasma mai tushen chlorine (silicon + chlorine) tare da zaɓin etching polysilicon. Don layin rufin ƙasa, ya kamata a zana fim ɗin silicon dioxide a matakai biyu ta amfani da iskar gas mai tushen carbon fluoride (silicon dioxide + carbon tetrafluoride) tare da zaɓin etching mai ƙarfi da inganci.
3. Tsarin etching na ion mai amsawa (RIE ko etching na physicochemical)
Hoto na 3. Fa'idodin etching na ion mai amsawa (anisotropy da ƙimar etching mai yawa)
Plasma tana ɗauke da radicals na kyauta na isotropic da cations na anisotropic, to ta yaya take yin etching na anisotropic?
Ana yin aikin busar da fata ta plasma ta hanyar yin amfani da ion etching (RIE, Reactive Ion Etching) ko aikace-aikace bisa ga wannan hanyar. Babban hanyar RIE ita ce ta raunana ƙarfin ɗaurewa tsakanin ƙwayoyin da aka yi niyya a cikin fim ɗin ta hanyar kai hari ga yankin etching da cations na anisotropic. Yankin da ya raunana yana sha ta hanyar free radicals, tare da ƙwayoyin da suka haɗu da Layer, suna canzawa zuwa iskar gas (wani abu mai canzawa) sannan a sake shi.
Duk da cewa free radicals suna da halaye na isotropic, ƙwayoyin da suka samar da saman ƙasa (wanda ƙarfin ɗaurewarsu ya raunana ta hanyar harin cations) suna iya kamawa cikin sauƙi ta hanyar free radicals kuma su canza su zuwa sabbin mahadi fiye da bangon gefe tare da ƙarfin ɗaurewa mai ƙarfi. Saboda haka, ƙwanƙwasa ƙasa ya zama babban abu. Ƙwayoyin da aka kama sun zama iskar gas tare da free radicals, waɗanda ake narkewa kuma ana sake su daga saman ƙarƙashin aikin injin.
A wannan lokacin, ana haɗa cations da aka samu ta hanyar aikin jiki da kuma free radicals da aka samu ta hanyar aikin sinadarai don etching na zahiri da na sinadarai, kuma ƙimar etching (Etch Rate, matakin etching a cikin wani lokaci) ya ƙaru da sau 10 idan aka kwatanta da yanayin etching na cationic ko etching na free radicals kawai. Wannan hanyar ba wai kawai za ta iya ƙara yawan etching na anisotropic downward etching ba, har ma da magance matsalar ragowar polymer bayan etching. Wannan hanyar ana kiranta reactive ion etching (RIE). Mabuɗin nasarar etching na RIE shine a nemo iskar gas mai tushen plasma da ta dace da etching na fim ɗin. Lura: Etching na plasma shine etching na RIE, kuma ana iya ɗaukar su biyun a matsayin ra'ayi ɗaya.
4. Ƙimar Etch da Babban Ma'aunin Aiki
Siffa ta 4. Ma'aunin Ayyukan Etch na Core da ke da alaƙa da Ƙimar Etch
Yawan etch yana nufin zurfin fim ɗin da ake sa ran zai isa cikin minti ɗaya. To me ake nufi da cewa yawan etch ya bambanta daga ɓangare zuwa ɓangare akan wafer ɗaya?
Wannan yana nufin cewa zurfin etch ya bambanta daga ɓangare zuwa ɓangare akan wafer. Saboda wannan dalili, yana da matuƙar muhimmanci a saita ƙarshen ma'aunin (EOP) inda etching ya kamata ya tsaya ta hanyar la'akari da matsakaicin ƙimar etch da zurfin etch. Ko da an saita EOP, har yanzu akwai wasu wurare inda zurfin etch ya fi zurfi (over-etched) ko ƙasa (under-etched) fiye da yadda aka tsara tun farko. Duk da haka, under-etching yana haifar da lalacewa fiye da over-etching yayin etching. Domin a yanayin under-etching, ɓangaren under-etching zai kawo cikas ga ayyukan da ke gaba kamar dasa ion.
A halin yanzu, zaɓin (wanda aka auna ta hanyar ƙimar etch) muhimmin alamar aiki ne na tsarin etching. Ma'aunin aunawa ya dogara ne akan kwatanta ƙimar etch na Layer na abin rufe fuska (fim ɗin photoresist, fim ɗin oxide, fim ɗin silicon nitride, da sauransu) da Layer na manufa. Wannan yana nufin cewa mafi girman zaɓin, da sauri ake etch ɗin abin da aka nufa. Mafi girman matakin ƙaramin abu, mafi girman buƙatar zaɓin shine don tabbatar da cewa za a iya gabatar da kyawawan tsare-tsare daidai. Tunda alkiblar etching madaidaiciya ce, zaɓin etching na cationic yana da ƙasa, yayin da zaɓin etching mai tsauri yana da yawa, wanda ke inganta zaɓin RIE.
5. Tsarin sassaka
Hoto na 5. Tsarin yin ado
Da farko, ana sanya wafer ɗin a cikin tanda mai dumama iska tare da zafin da ke tsakanin 800 da 1000℃, sannan a samar da fim ɗin silicon dioxide (SiO2) mai ƙarfin kariya mai yawa a saman wafer ɗin ta hanyar busasshiyar hanya. Na gaba, ana shigar da tsarin adanawa don samar da layin silicon ko layin sarrafawa akan fim ɗin oxide ta hanyar adana tururin sinadarai (CVD)/tabar jiki (PVD). Idan an samar da layin silicon, ana iya yin tsarin watsa tururin iska don ƙara yawan aiki idan ya cancanta. A lokacin aikin watsa tururin iska, sau da yawa ana ƙara ƙazanta da yawa akai-akai.
A wannan lokacin, ya kamata a haɗa layin rufi da kuma layin polysilicon don yin fenti. Da farko, ana amfani da mai hana haske. Daga baya, ana sanya abin rufe fuska a kan fim ɗin mai hana haske kuma ana yin fallasa danshi ta hanyar nutsewa don buga tsarin da ake so (wanda ido ba zai iya gani ba) akan fim ɗin mai hana haske. Lokacin da aka bayyana tsarin ta hanyar haɓakawa, ana cire mai hana haske a yankin da ke da tasirin haske. Sannan, ana canza wafer ɗin da aka sarrafa ta hanyar aikin photolithography zuwa tsarin fenti don yin fenti busasshe.
Ana yin aikin etching busasshe ne ta hanyar etching mai amsawa da ion (RIE), wanda ake maimaita etching ta hanyar maye gurbin iskar gas mai tushe da ta dace da kowane fim. Duk etching busasshe da etching mai danshi suna da nufin ƙara rabon al'amari (ƙimar A/R) na etching. Bugu da ƙari, ana buƙatar tsaftacewa akai-akai don cire polymer da aka tara a ƙasan ramin (rata da aka samar ta hanyar etching). Muhimmin abu shine cewa duk masu canji (kamar kayan aiki, iskar gas mai tushe, lokaci, tsari da jerin) ya kamata a daidaita su ta hanyar halitta don tabbatar da cewa maganin tsaftacewa ko iskar gas mai tushe ta plasma zai iya gudana zuwa ƙasan ramin. Canji kaɗan a cikin wani mai canji yana buƙatar sake lissafin wasu masu canji, kuma ana maimaita wannan tsarin sake lissafin har sai ya cika manufar kowane mataki. Kwanan nan, yadudduka monoatomic kamar yadudduka na atom Layer deposition (ALD) sun zama sirara da wahala. Saboda haka, fasahar etching tana tafiya zuwa ga amfani da ƙananan yanayin zafi da matsin lamba. Tsarin etching yana da nufin sarrafa ma'aunin mahimmanci (CD) don samar da kyawawan alamu da kuma tabbatar da cewa an guji matsalolin da tsarin etching ke haifarwa, musamman ƙarancin etching da matsalolin da suka shafi cire ragowar. Makaloli biyu da ke sama game da gyaran gashi suna da nufin bai wa masu karatu fahimtar manufar tsarin gyaran gashi, cikas ga cimma burin da ke sama, da kuma alamun aiki da ake amfani da su don shawo kan irin waɗannan cikas.
Lokacin Saƙo: Satumba-10-2024