1. Gabatarwa
Dasa ion yana ɗaya daga cikin manyan matakai a cikin masana'antar da'ira mai haɗaka. Yana nufin aiwatar da hanzarin ƙwayar ion zuwa wani makamashi (yawanci a cikin keV zuwa MeV) sa'an nan kuma shigar da shi a cikin saman wani abu mai mahimmanci don canza halayen jiki na saman kayan. A cikin hadedde kewaye tsari, da m abu yawanci silicon, da implanted najasa ions yawanci boron ions, phosphorus ions, arsenic ions, indium ions, germanium ions, da dai sauransu The implanted ions iya canza conductivity na surface na m. abu ko kafa hanyar PN. Lokacin da aka rage girman fasalin haɗaɗɗun da'irori zuwa zamanin ƙananan micron, tsarin dasa ion an yi amfani da shi sosai.
A cikin haɗe-haɗe da tsarin masana'antu, ion implantation yawanci amfani da zurfin binne yadudduka, baya doped rijiyoyin, kofa ƙarfin lantarki gyara, tushen da lambatu tsawo implantation, tushen da lambatu implantation, polysilicon ƙofar doping, forming PN junctions da resistors / capacitors, da dai sauransu. A cikin aiwatar da shirye-shiryen silica substrate kayan a kan insulators, oxide Layer da aka binne aka yafi kafa ta high-tattara oxygen ion implantation, ko da hankali yankan da aka samu ta high-tattara hydrogen ion implantation.
Ion implantation ana yin shi ta hanyar ion implanter, kuma mafi mahimmancin sigogin tsari shine kashi da makamashi: kashi yana ƙayyade ƙaddamarwar ƙarshe, kuma makamashi yana ƙayyade kewayon (watau zurfin) na ions. Dangane da buƙatun ƙira na na'ura daban-daban, yanayin dasawa ya kasu kashi-kashi mai ƙarfi mai ƙarfi, matsakaici-matsakaici-matsakaici, matsakaici-matsakaici mai ƙarancin kuzari, ko ƙarancin ƙarancin kuzari. Domin samun sakamako mai kyau na shigarwa, ya kamata a samar da nau'i-nau'i daban-daban don bukatun tsari daban-daban.
Bayan shigar da ion, gabaɗaya ya zama dole a aiwatar da babban yanayin zafi don gyara lalacewar lattice da ta haifar da ion da kunna ions na ƙazanta. A cikin tsarin da'ira na al'ada, duk da cewa zafin jiki na annealing yana da babban tasiri a kan doping, zafin tsarin dasa ion kanta ba shi da mahimmanci. A nodes na fasaha da ke ƙasa da 14nm, wasu matakan dasa ion suna buƙatar yin aiki a cikin ƙananan yanayin zafi ko yanayin zafi don canza tasirin lalacewar lattice, da dai sauransu.
2. ion tsarin shigarwa
2.1 Ka'idodi na asali
Dasa ion tsari ne na ƙara kuzari da aka haɓaka a cikin shekarun 1960 wanda ya zarce dabarun yaɗuwar al'ada a yawancin fannoni.
Babban bambance-bambance tsakanin ion implantation doping da gargajiya diffusion doping su ne kamar haka:
(1) Rarraba ƙaddamarwar ƙazanta a cikin yankin doped ya bambanta. Matsakaicin ƙazanta mafi girma na ion implantation yana cikin kristal, yayin da mafi girman ƙazanta na watsawa yana saman saman crystal.
(2) Ion implantation wani tsari ne da aka yi a dakin da zafin jiki ko ma ƙananan zafin jiki, kuma lokacin samarwa yana da gajeren lokaci. Yadawa doping yana buƙatar dogon magani mai zafin jiki.
(3) Sanya ion yana ba da damar ƙarin sassauƙa da daidaitaccen zaɓi na abubuwan da aka dasa.
(4) Tun da ƙazanta suna da tasiri ta hanyar yaduwar zafin jiki, nau'in igiyar ruwa da aka samo ta hanyar ion implantation a cikin crystal ya fi kyau fiye da nau'in igiyar ruwa da aka samu ta hanyar watsawa a cikin crystal.
(5) Ion implantation yawanci yana amfani da photoresist a matsayin abin rufe fuska, amma yaduwar doping yana buƙatar girma ko sanya fim ɗin wani kauri azaman abin rufe fuska.
(6) Ion implantation ya maye gurbin yaduwa kuma ya zama babban tsarin doping a cikin kera na'urori masu haɗaka a yau.
Lokacin da wani abin da ya faru ion katako tare da wani makamashi ya jefar da wani tabbataccen manufa (yawanci wafer), ions da atom ɗin da ke saman abin da ake nufi za su yi mu'amala iri-iri, kuma su tura makamashi zuwa ga atom ɗin da aka yi niyya ta wata hanya don tada hankali ko ionize. su. Hakanan ions na iya rasa wani adadin kuzari ta hanyar canja wuri, kuma a ƙarshe za a warwatsa su ta hanyar atom ɗin da aka yi niyya ko kuma su tsaya a cikin abin da aka yi niyya. Idan ions da aka yi musu allura sun fi nauyi, yawancin ion ɗin za a yi musu allurar cikin ƙaƙƙarfan manufa. Akasin haka, idan ions ɗin da aka yi wa allurar sun yi sauƙi, yawancin ion ɗin da aka yi musu za su billa daga saman da ake nufi. Ainihin, waɗannan ions masu ƙarfi da aka allura a cikin maƙasudin za su yi karo da atom ɗin lattice da electrons a cikin maƙasudin maƙasudi zuwa digiri daban-daban. Daga cikin su, ana iya ɗaukar karo tsakanin ions da ƙwararrun ƙwayoyin zarra a matsayin karo na roba saboda suna kusa da taro.
2.2 Babban sigogi na ion implantation
Ion dasa shuki tsari ne mai sassauƙa wanda dole ne ya dace da ƙirar guntu mai tsauri da buƙatun samarwa. Muhimman sigogin dasa ion sune: kashi, kewayo.
Kashi (D) yana nufin adadin ions da aka yi allura a kowane yanki na yanki na siliki wafer, a cikin atom a kowace centimita murabba'i (ko ions a kowace centimita murabba'in). Ana iya ƙididdige D ta hanyar dabara mai zuwa:
Inda D shine adadin dasawa (yawan ions/ yanki); t shine lokacin dasawa; Ni ne hasken wutar lantarki; q shine cajin da ion ke ɗauka (cajin ɗaya shine 1.6 × 1019C[1]); kuma S shine wurin dasawa.
Ɗaya daga cikin manyan dalilan da ya sa ion implantation ya zama muhimmiyar fasaha a masana'antar wafer silicon shine cewa yana iya maimaita dasa kashi iri ɗaya na ƙazanta a cikin wafern silicon. Mai sakawa ya cimma wannan burin tare da taimakon ingantaccen cajin ions. Lokacin da ingantattun ions na ƙazanta suka samar da katako na ion, ana kiran adadin kwararar ion beam current, wanda aka auna a mA. Matsakaicin matsakaici da ƙananan igiyoyin ruwa shine 0.1 zuwa 10 mA, kuma kewayon manyan igiyoyin ruwa shine 10 zuwa 25 mA.
Girman ion beam current shine maɓalli mai mahimmanci wajen ayyana kashi. Idan halin yanzu ya ƙaru, adadin atom ɗin ƙazanta da aka dasa kowane lokaci na raka'a shima yana ƙaruwa. Babban halin yanzu yana da amfani don haɓaka yawan wafer silicon (alurar da ƙarin ions a kowane lokacin samarwa), amma kuma yana haifar da matsalolin daidaito.
3. ion kayan aikin dasawa
3.1 Babban Tsarin
Kayan aiki na ion sun haɗa da na'urori na asali 7:
① ion tushen da abin sha;
② Mass analyzer (watau magnetin nazari);
③ bututu mai sauri;
④ faifan dubawa;
⑤ electrostatic neutralization tsarin;
⑥ tsarin tsari;
⑦ tsarin kula da kashi.
All kayayyaki suna cikin yanayi mara kyau wanda tsarin injin ya kafa. Ana nuna ainihin zanen tsarin ion implanter a cikin hoton da ke ƙasa.
(1)Ion asalin:
Yawancin lokaci a cikin ɗaki ɗaya kamar injin tsotsa. Abubuwan dattin da ke jira don allura dole ne su kasance a cikin yanayin ion don sarrafa su da haɓaka ta hanyar wutar lantarki. Mafi yawan amfani da B+, P+, As+, da sauransu ana samun su ta hanyar ionizing atoms ko kwayoyin halitta.
Abubuwan ƙazanta da aka yi amfani da su sune BF3, PH3 da AsH3, da dai sauransu, kuma ana nuna tsarin su a cikin hoton da ke ƙasa. Electron din da Filament ya fitar ya yi karo da atom din gas don samar da ion. Yawanci ana samar da na'urorin lantarki daga tushen filament tungsten mai zafi. Misali, tushen ion Berners, ana shigar da filament na cathode a cikin ɗakin baka tare da shigar da iskar gas. Bangon ciki na ɗakin baka shine anode.
Lokacin da aka gabatar da tushen iskar gas, babban halin yanzu yana wucewa ta cikin filament, kuma ana amfani da ƙarfin lantarki na 100 V tsakanin ingantattun na'urori masu kyau da kuma mara kyau, wanda zai haifar da wutar lantarki mai ƙarfi a kewayen filament. Ana haifar da ion mai kyau bayan da manyan makamashin lantarki suka yi karo da kwayoyin iskar gas.
Maganar maganadisu ta waje tana amfani da filin maganadisu daidai da filament don ƙara ionization da daidaita plasma. A cikin ɗakin baka, a ɗayan ƙarshen dangane da filament, akwai mai cajin da ba daidai ba wanda ke nuna electrons baya don inganta haɓakawa da ingancin electrons.
(2)Sha:
Ana amfani da shi don tattara ingantattun ions da aka samar a cikin ɗakin baka na tushen ion kuma a samar da su a cikin katako na ion. Tunda ɗakin baka shine anode kuma cathode yana da mummunar matsa lamba akan electrode na tsotsa, filin lantarki da aka samar yana sarrafa ions masu kyau, yana sa su matsawa zuwa wutar lantarki kuma za a fitar da su daga ion slit, kamar yadda aka nuna a cikin hoton da ke ƙasa. . Mafi girman ƙarfin filin lantarki, mafi girman ƙarfin motsa jiki da ions ke samu bayan haɓakawa. Hakanan akwai wutar lantarki na kashewa akan na'urar tsotsa don hana tsangwama daga electrons a cikin plasma. A lokaci guda, na'urar kashewa na iya samar da ions zuwa cikin katako na ion kuma ya mayar da su zuwa cikin rafi mai kama da ion katako don ya wuce ta wurin mai sakawa.
(3)Mass analyzer:
Ana iya samun nau'ikan ions da yawa da aka samar daga tushen ion. A ƙarƙashin haɓakar ƙarfin lantarki na anode, ions suna motsawa cikin babban sauri. Ions daban-daban suna da raka'o'in taro na atomic daban-daban da ma'auni daban-daban na taro-zuwa caji.
(4)Accelerator tube:
Domin samun saurin gudu, ana buƙatar makamashi mafi girma. Bugu da ƙari ga wutar lantarki da aka samar da anode da mass analyzer, ana buƙatar filin lantarki da aka samar a cikin bututu mai haɓaka don haɓakawa. Bututu mai haɓakawa ya ƙunshi jerin na'urori masu auna firikwensin da aka keɓe ta hanyar dielectric, kuma ƙarancin ƙarfin lantarki akan na'urori yana ƙaruwa a jere ta hanyar haɗin jerin. Mafi girman jimlar ƙarfin lantarki, mafi girman saurin da ions ke samu, wato, mafi girman ƙarfin da ake ɗauka. Ƙarfi mai ƙarfi na iya ƙyale ions na ƙazanta a zurfafa zurfafa a cikin wafer silicon don samar da haɗin gwiwa mai zurfi, yayin da ƙananan makamashi za a iya amfani da shi don yin haɗin kai marar zurfi.
(5)Ana duba diski
Hasken ion da aka mayar da hankali akai yawanci kadan ne a diamita. Diamita ta wurin katako mai matsakaicin katako na yanzu yana da kusan 1 cm, kuma na babban katako na yanzu yana da kusan cm 3. Dole ne a rufe dukkan wafer silicon ta hanyar dubawa. Maimaituwar shigar kashi ana ƙaddara ta hanyar dubawa. Yawancin lokaci, akwai nau'ikan tsarin sikanin implanter iri huɗu:
① gwajin lantarki;
② dubawar injiniya;
③ duban matasan;
④ bincike na layi daya.
(6)A tsaye tsarin neutralization na wutar lantarki:
A lokacin aikin dasa, ion katako ya bugi wafer siliki kuma yana haifar da cajin taru a saman abin rufe fuska. Sakamakon tarin cajin yana canza ma'aunin cajin a cikin katako na ion, yana sa wurin katako ya fi girma da rarraba kashi mara daidaituwa. Yana iya ma karya ta saman oxide Layer kuma ya haifar da gazawar na'urar. Yanzu, wafer silicon da ion beam yawanci ana sanya su a cikin tsayayyen yanayin plasma mai girma da ake kira tsarin shawa na lantarki na plasma, wanda zai iya sarrafa cajin wafer silicon. Wannan hanyar tana fitar da electrons daga plasma (yawanci argon ko xenon) a cikin ɗakin baka dake cikin hanyar ion beam kuma kusa da wafer silicon. Ana tace plasma ɗin kuma na'urorin lantarki na biyu kawai zasu iya isa saman wafer silicon don kawar da ingantaccen cajin.
(7)Tsarin rami:
Allurar ion katako a cikin wafern silicon yana faruwa a cikin ɗakin sarrafawa. Gidan tsari wani muhimmin sashi ne na mai sanyawa, gami da tsarin dubawa, tashar tashar tashar da ke da makulli don lodawa da sauke wafern siliki, tsarin canja wurin wafer silicon, da tsarin sarrafa kwamfuta. Bugu da kari, akwai wasu na'urori don saka idanu akan allurai da sarrafa tasirin tashoshi. Idan ana amfani da sikanin injina, tashar tashar za ta yi girma sosai. The injin daki dakin da ake pumped zuwa kasa matsa lamba da ake bukata da tsari ta Multi-mataki inji famfo, a turbomolecular famfo, da kuma wani kumburi famfo, wanda shi ne kullum game da 1 × 10-6Torr ko žasa.
(8)Tsarin sarrafa sashi:
Ana yin sa ido kan kashi na ainihi a cikin mai saka ion ta hanyar auna katakon ion zuwa wafer silicon. Ana auna ion beam current ta amfani da firikwensin da ake kira Kofin Faraday. A cikin tsarin Faraday mai sauƙi, akwai firikwensin na yanzu a cikin hanyar ion beam wanda ke auna halin yanzu. Duk da haka, wannan yana ba da matsala, yayin da ion beam yana amsawa tare da firikwensin kuma ya samar da electrons na biyu wanda zai haifar da kuskuren karatun yanzu. Tsarin Faraday na iya murƙushe electrons na biyu ta amfani da filayen lantarki ko maganadisu don samun ingantaccen karatun katako na yanzu. A halin yanzu da aka auna ta tsarin Faraday ana ciyar da shi zuwa cikin mai sarrafa kashi na lantarki, wanda ke aiki azaman mai tarawa na yanzu (wanda ke ci gaba da tara ma'aunin katako na yanzu). Ana amfani da mai sarrafawa don danganta jimlar halin yanzu zuwa daidai lokacin dasawa da ƙididdige lokacin da ake buƙata don takamaiman kashi.
3.2 Gyara lalacewa
Shigarwa na ion zai fitar da kwayoyin halitta daga tsarin lattice kuma ya lalata lattice na silicon wafer. Idan kashi da aka dasa yana da girma, Layer da aka dasa zai zama amorphous. Bugu da kari, ions da aka dasa a asali ba sa mamaye wuraren lattice na siliki, amma zauna a cikin guraben tazara. Wadannan ƙazantar tsaka-tsaki za a iya kunna su ne kawai bayan tsari mai zafi mai zafi.
Annealing na iya dumama wafer siliki da aka dasa don gyara lahani na lattice; yana iya matsar da ƙazanta na ƙazanta zuwa wuraren lattice kuma kunna su. Matsakaicin zafin da ake buƙata don gyara lahanin lattice shine kusan 500 ° C, kuma zafin da ake buƙata don kunna atom ɗin ƙazanta shine kusan 950 ° C. Kunna ƙazanta yana da alaƙa da lokaci da zafin jiki: tsayin lokaci kuma mafi girman zafin jiki, ƙarin ƙazantattun suna kunnawa. Akwai hanyoyi guda biyu na asali don annealing silicon wafers:
① zafi mai zafi annealing tanderu;
② saurin kawar da zafi (RTA).
Babban zafin wutar tanderun da ke murƙushe tanderu: Babban zafin tanderun murɗawa hanya ce ta gargajiya, wacce ke amfani da tanderun zafin jiki don dumama wafer silicon zuwa 800-1000 ℃ kuma a ajiye shi na mintuna 30. A wannan zafin jiki, ƙwayoyin siliki suna komawa zuwa matsayi na lattice, kuma ƙazantattun atom na iya maye gurbin ƙwayoyin silicon kuma su shiga cikin lattice. Duk da haka, maganin zafi a irin wannan zafin jiki da lokaci zai haifar da yaduwar ƙazanta, wanda shine abin da masana'antun masana'antun zamani na IC ba sa so su gani.
Rapid thermal Annealing: Rapid thermal annealing (RTA) yana kula da wafers silicon tare da haɓakar zafin jiki mai saurin gaske da ɗan gajeren lokaci a zafin da aka yi niyya (yawanci 1000°C). Annealing na dasa wafers silicon yawanci ana yin su a cikin injin sarrafa zafi mai sauri tare da Ar ko N2. Tsarin haɓakar zafin jiki mai sauri da ɗan gajeren lokaci na iya haɓaka gyare-gyaren lahani na lattice, kunna ƙazanta da hana yaduwar ƙazanta. Hakanan RTA na iya rage haɓaka haɓakar ɗan lokaci kuma ita ce hanya mafi kyau don sarrafa zurfin junction a cikin junction implants.
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