Ta yaya yadudduka na epitaxial ke taimakawa na'urorin semiconductor?

Asalin sunan epitaxial wafer

Da farko, bari mu yaɗa wani ƙaramin ra'ayi: shirye-shiryen wafer ya ƙunshi manyan hanyoyin haɗi guda biyu: shirye-shiryen substrate da tsarin epitaxial. Substrate ɗin wafer ne da aka yi da kayan semiconductor guda ɗaya. Substrate ɗin zai iya shiga kai tsaye cikin tsarin kera wafer don samar da na'urorin semiconductor, ko kuma ana iya sarrafa shi ta hanyar hanyoyin epitaxial don samar da wafers na epitaxial. Epitaxy yana nufin tsarin girma sabon Layer na lu'ulu'u ɗaya akan wani abu mai lu'ulu'u ɗaya wanda aka sarrafa shi da kyau ta hanyar yankewa, niƙawa, gogewa, da sauransu. Sabon lu'ulu'u ɗaya na iya zama abu ɗaya da substrate, ko kuma yana iya zama wani abu daban (homoneous) epitaxy ko heteroepitaxy). Saboda sabon layin lu'ulu'u guda ɗaya yana faɗaɗawa kuma yana girma bisa ga matakin lu'ulu'u na substrate, ana kiransa Layer epitaxial (kauri yawanci microns ne kaɗan, idan aka ɗauki silicon a matsayin misali: ma'anar girma na silicon epitaxial yana kan wani sinadari na silicon guda ɗaya tare da takamaiman yanayin lu'ulu'u. Layer na lu'ulu'u mai kyakkyawan tsarin lattice da juriya daban-daban da kauri tare da yanayin lu'ulu'u iri ɗaya kamar yadda aka girma substrate), kuma substrate tare da layin epitaxial ana kiransa epitaxial wafer (epitaxial wafer = epitaxial Layer + substrate). Lokacin da aka yi na'urar akan layin epitaxial, ana kiransa epitaxial mai kyau. Idan an yi na'urar akan substrate, ana kiransa reverse epitaxy. A wannan lokacin, Layer epitaxial yana taka rawa kawai.

Wafer mai gogewa

Hanyoyin girma na Epitaxial

Epitaxy na ƙwayoyin halitta (MBE): Fasaha ce ta haɓakar epitaxial na semiconductor da ake yi a ƙarƙashin yanayin iska mai ƙarfi. A cikin wannan dabarar, ana fitar da kayan tushe a cikin siffar harsashin ƙwayoyin halitta ko ƙwayoyin halitta sannan a ajiye su a kan wani abu mai kama da lu'ulu'u. MBE wata fasaha ce mai matuƙar daidaito kuma mai iya sarrafa sinadari mai kama da semiconductor wadda za ta iya sarrafa kauri na kayan da aka ajiye a matakin atom.
CVD na ƙarfe na halitta (MOCVD): A cikin tsarin MOCVD, ana samar da iskar gas ta ƙarfe da iskar hydride mai ɗauke da abubuwan da ake buƙata ga substrate a yanayin zafi mai dacewa, ana yin aikin sinadarai don samar da kayan semiconductor da ake buƙata, kuma ana ajiye su a kan substrate ɗin a kan, yayin da sauran mahaɗan da samfuran amsawa ke fitarwa.
Epitaxy na lokacin Vapor (VPE): Epitaxy na lokacin Vapor muhimmin fasaha ne da ake amfani da shi wajen samar da na'urorin semiconductor. Babban ƙa'idar ita ce jigilar tururin abubuwan da ke cikin iskar gas mai ɗaukar kaya, da kuma sanya lu'ulu'u a kan substrate ta hanyar halayen sinadarai.

Waɗanne matsaloli ne tsarin epitaxy ke magancewa?

Kayan lu'ulu'u guda ɗaya ne kawai ba za su iya biyan buƙatun da ake buƙata na ƙera na'urori daban-daban na semiconductor ba. Saboda haka, an ƙirƙiro ci gaban epitaxial, wata fasaha mai sirara ta girma lu'ulu'u guda ɗaya, a ƙarshen 1959. To wace irin gudunmawa ce fasahar epitaxy ke bayarwa ga ci gaban kayan?

Ga silicon, lokacin da fasahar ci gaban epitaxial na silicon ta fara, lokaci ne mai wahala ga samar da transistors masu yawan mita da ƙarfi na silicon. Daga mahangar ka'idodin transistor, don samun mita mai yawa da ƙarfi mai yawa, ƙarfin wutar lantarki na yankin mai tarawa dole ne ya kasance mai girma kuma juriyar jerin dole ne ya zama ƙarami, wato, raguwar ƙarfin jikewa dole ne ya zama ƙarami. Na farko yana buƙatar cewa juriyar kayan a yankin tarawa ya zama mai girma, yayin da na biyu yana buƙatar juriyar kayan a yankin tarawa ya zama ƙasa. Lardunan biyu sun saba wa juna. Idan an rage kauri na kayan a yankin tarawa don rage juriyar jerin, wafer ɗin silicon zai yi siriri kuma ya yi rauni don a sarrafa shi. Idan juriyar kayan ta ragu, zai saba wa buƙata ta farko. Duk da haka, haɓaka fasahar epitaxial ya yi nasara. an warware wannan matsala.

Magani: Haɓaka wani Layer na epitaxial mai juriya mai ƙarfi akan wani substrate mai ƙarancin juriya, sannan a yi na'urar a kan Layer na epitaxial. Wannan Layer na epitaxial mai juriya mai ƙarfi yana tabbatar da cewa bututun yana da ƙarfin lantarki mai ƙarfi, yayin da substrate mai ƙarancin juriya Hakanan yana rage juriyar substrate, ta haka yana rage raguwar ƙarfin lantarki mai cika, ta haka ne yake warware saɓani tsakanin su biyun.

Bugu da ƙari, fasahar epitaxy kamar su epitaxy na vapor phase da epitaxy na ruwa na GaAs da sauran kayan semiconductor na kwayoyin halitta na III-V, II-VI da sauran kayan semiconductor na kwayoyin halitta suma an haɓaka su sosai kuma sun zama tushen yawancin na'urorin microwave, na'urorin optoelectronic, da wutar lantarki. Fasaha ce mai mahimmanci don samar da na'urori, musamman nasarar amfani da fasahar epitaxy na ƙwayoyin halitta da fasahar epitaxy na ƙarfe na ƙarfe a cikin ƙananan yadudduka, superlattices, rijiyoyin quantum, superlattices masu rauni, da epitaxy na bakin ciki na matakin atomic, wanda sabon mataki ne a cikin binciken semiconductor. Ci gaban "injiniyar bel ɗin makamashi" a fagen ya kafa harsashi mai ƙarfi.

A aikace-aikace na zahiri, kusan koyaushe ana yin na'urorin semiconductor masu faɗi da faɗi akan layin epitaxial, kuma wafer ɗin silicon carbide da kansa yana aiki ne kawai a matsayin substrate. Saboda haka, sarrafa layin epitaxial muhimmin ɓangare ne na masana'antar semiconductor mai faɗi da faɗi.

Manyan ƙwarewa guda 7 a fannin fasahar epitaxy

1. Ana iya shuka manyan yadudduka masu juriya (ƙananan) epitaxial ta hanyar epitaxial akan ƙananan substrates masu juriya (masu girma).
2. Ana iya shuka layin epitaxial na nau'in N (P) ta hanyar epitaxial akan nau'in P (N) don samar da haɗin PN kai tsaye. Babu matsalar diyya yayin amfani da hanyar watsawa don yin haɗin PN akan wani abu guda ɗaya na lu'ulu'u.
3. Idan aka haɗa shi da fasahar rufe fuska, ana yin zaɓin haɓakar epitaxial a wurare da aka keɓe, wanda ke haifar da yanayi don samar da da'irori masu haɗawa da na'urori masu tsari na musamman.
4. Ana iya canza nau'in da yawan amfani da maganin doping bisa ga buƙatu yayin tsarin ci gaban epitaxial. Canjin yawan amfani da maganin na iya zama canji kwatsam ko canji a hankali.
5. Yana iya girma nau'ikan mahadi daban-daban, masu layuka da yawa, masu sassa daban-daban da kuma yadudduka masu siriri sosai tare da sassa daban-daban.
6. Ana iya yin girman epitaxial a yanayin zafi ƙasa da wurin narkewar kayan, ana iya sarrafa saurin girma, kuma ana iya cimma girman epitaxial na kauri matakin atomic.
7. Yana iya shuka kayan lu'ulu'u guda ɗaya waɗanda ba za a iya ja ba, kamar GaN, yadudduka na lu'ulu'u guda ɗaya na mahaɗan tertiary da quaternary, da sauransu.