Taw qhia rau Photolithography Technology
Kev Txhim Kho Keeb Kwm ntawm Photolithography Technology
Txij li thaum Jack S. Kilby tau tsim lub ntiaj teb thawj zaug kev sib koom ua ke rau lub Cuaj Hlis 12, 1958, kev sib koom ua ke tau ntsib kev loj hlob sai rau ntau tshaj 50 xyoo. Qhov tsawg kawg kab dav yog tam sim no ntawm 20 thiab 30nm. lub sijhawm, nkag mus rau qhov tob submicron ntau yam. Photolithography thev naus laus zis, ib qho ntawm cov thev naus laus zis tseem ceeb, kuj tau hloov zuj zus los ntawm kev siv thawj zaug ntawm cov iav tsom iav zoo ib yam li cov khoom siv yees duab rau niaj hnub no immersion-type 1.35 siab cov lej aperture, uas muaj peev xwm tswj tau thiab kho cov duab zoo, nrog txoj kab uas hla. ntawm ntau tshaj ib nrab ib 'meter' thiab ib tug luj ntawm ib nrab ib ton. loj loj lens teeb. Lub luag haujlwm ntawm photolithography yog luam tawm cov qauv hluav taws xob semiconductor mus rau silicon wafers txheej los ntawm txheej. Nws lub tswv yim los ntawm kev siv tshuab luam ntawv ntev. Qhov txawv yog tias luam ntawv sau cov ntaub ntawv los ntawm kev siv tus cwj mem los tsim cov kev hloov hauv lub teeb pom kev ntawm daim ntawv. , thaum photolithography siv photochemical cov tshuaj tiv thaiv ntawm lub teeb thiab lub teeb-sensitive tshuaj kom ua tiav qhov sib txawv.
Tshuab luam ntawv thawj zaug tshwm sim nyob rau hauv lub lig Han Dynasty nyob rau hauv Tuam Tshoj. Ntau tshaj li 800 xyoo tom qab, Bi Sheng ntawm Song Dynasty tau hloov kho kev hloov kho thiab hloov kho cov ntawv luam tawm mus rau hauv hom kev luam ntawv, uas tom qab ntawd tsim sai heev. Niaj hnub no, laser phototypesetting tshuab tau tsim. "Photolithography" nyob rau hauv lub siab tam sim no pib nrog kev sim ntawm Alois Senefedler nyob rau hauv 1798. Thaum nws sim luam tawm nws phau ntawv nyob rau hauv Munich, lub teb chaws Yelemees, nws nrhiav tau hais tias yog hais tias nws siv roj cwj mem kos duab rau porous limestone thiab moistened lub undrawn cheeb tsam nrog dej. , tus cwj mem tsuas yog Glue qhov twg koj kos nrog cwj mem. Cov txheej txheem no hu ua Lithography, lossis kos duab rau ntawm pob zeb. Lithography yog lub forerunner ntawm niaj hnub multi-sau npe.
Cov txheej txheem yooj yim ntawm photolithography
Txawm hais tias muaj qee qhov zoo sib xws, photolithography hauv kev sib xyaw ua ke siv lub teeb hloov ntawm tus cwj mem, thiab cov cheeb tsam uas muaj tus cwj mem thiab tsis muaj tus cwj mem ua rau thaj chaw uas muaj lub teeb thiab tsis muaj lub teeb ntawm lub ntsej muag. Hauv kev lag luam hluav taws xob sib xyaw ua ke, lithography tseem hu ua photolithography, lossis lithography. Ib yam li roj raws li tus cwj mem tau xaiv tso rau ntawm limestone, lub teeb tsuas tuaj yeem dhau los ntawm qhov chaw pob tshab ntawm lub npog ntsej muag, thiab lub teeb pom kev zoo tau kaw rau ntawm cov khoom siv lub teeb hu ua photoresist. Daim duab yooj yim schematic ntawm cov txheej txheem photolithography yog qhia hauv daim duab 7.1.
Vim tias cov photoresist dhau qhov kev hloov pauv ntawm kev sib cais ntawm tus tsim tawm tom qab raug ultraviolet (UV) lub teeb, tus qauv ntawm lub npog ntsej muag raug xa mus rau txheej txheej photoresist nyob rau sab saum toj ntawm silicon wafer. Cov chaw npog los ntawm photoresist tuaj yeem ua tiav kev hloov pauv ntawm lub npog ntsej muag ntxiv los ntawm kev tiv thaiv kev ua haujlwm ntxiv (xws li etching lossis ion implantation).
Txij li xyoo 1960, photolithography thev naus laus zis tuaj yeem muab faib ua peb hom hauv qab no: kev sib cuag, qhov sib thooj thiab qhov pom kev pom. Qhov ntxov tshaj plaws yog kev sib cuag lossis qhov sib thooj, uas yog qhov tseem ceeb ntawm kev tsim khoom mus txog rau nruab nrab -20 xyoo pua. Rau kev sib cuag, vim tias tsis muaj qhov sib txawv ntawm lub npog ntsej muag thiab sab saum toj ntawm silicon wafer, kev daws teeb meem tsis yog teeb meem. Txawm li cas los xij, txij li kev sib cuag yuav ua rau muaj qhov tsis xws luag vim hnav lub ntsej muag thiab photoresist, tib neeg thaum kawg xaiv qhov sib thooj. Tau kawg, nyob rau hauv qhov sib thooj, txawm hais tias muaj qhov tsis xws luag raug zam, qhov kev daws teeb meem ntawm qhov sib thooj yog txwv rau 3μm lossis loj dua vim muaj qhov sib txawv thiab lub teeb tawg. Lub theoretical txwv ntawm kev daws teeb meem ntawm kev sib thooj yog
Ntawm lawv,
k sawv cev rau cov tsis muaj photoresist, feem ntau ntawm 1 thiab 2;
CD sawv cev rau qhov tsawg kawg nkaus qhov loj, uas yog, qhov tseem ceeb ntawm qhov loj me, uas feem ntau sib haum rau qhov tsawg kawg nkaus daws tau qhov ntev ntawm kab dav;
λ hais txog qhov raug wavelength;
g sawv cev qhov deb ntawm lub npog ntsej muag mus rau qhov sib txawv ntawm qhov chaw photoresist (g=0 sib raug rau qhov raug)
Txij li thaum g feem ntau ntau dua 10μm (tsuas los ntawm qhov chaw tiaj tus ntawm daim npog ntsej muag thiab silicon wafer), qhov kev daws teeb meem zoo heev, xws li 3μm rau 450nm illumination wavelength. Kev sib cuag tuaj yeem ncav cuag 0.7μm.
Txhawm rau kov yeej ob qhov teeb meem ntawm qhov tsis xws luag thiab kev daws teeb meem, lub phiaj xwm kev nthuav dav raug pom zoo, uas lub npog ntsej muag thiab silicon wafer tau sib cais los ntawm ntau tshaj li ob peb centimeters. Cov lo ntsiab muag kho qhov muag yog siv los ua duab cov qauv lo ntsiab muag ntawm lub npog ntsej muag mus rau silicon wafer. Raws li kev ua lag luam xav tau rau cov chips loj dua thiab cov kab dav dav kev tswj hwm nruj dua, qhov kev nthuav dav pom kuj tau maj mam hloov zuj zus los ntawm qhov qub.
tag nrho silicon wafer raug rau tag nrho silicon wafer scanning raug (saib daim duab 7.2 (a))
ib kauj ruam-thiab-repeat raug (saib daim duab 7.2 (b))
step-and-scan exposure (saib daim duab 7.2 (c))
Tag nrho cov silicon wafer 1: 1 raug txoj kev muaj cov qauv yooj yim thiab tsis xav tau siab monochromaticity ntawm lub teeb. Txawm li cas los xij, raws li cov nti loj thiab silicon wafer loj loj dua thiab loj dua, thiab cov kab dav yuav zoo dua thiab zoo dua, qhov kho qhov muag tsis tuaj yeem tsim cov qauv mus rau tag nrho cov silicon wafer ib zaug yam tsis muaj kev cuam tshuam rau cov duab zoo, thiab thaiv kev cuam tshuam yuav tsis muaj kev cuam tshuam. .
Ib qho ntawm cov txheej txheem thaiv thaiv yog tag nrho cov silicon wafer scanning txoj kev, raws li qhia hauv daim duab 7.2 (a). Txoj kev no tsis tu ncua scans thiab nthuav tawm cov qauv ntawm lub npog ntsej muag mus rau silicon wafer los ntawm kev pom arc-zoo li daim teb. Lub kaw lus siv ob lub ntsej muag kheej kheej nrog tib lub axis kho qhov muag, thiab lawv lub vojvoog curvature thiab qhov kev ncua deb yog txiav txim siab los ntawm qhov yuav tsum tau ua kom tsis muaj aberration.
Txawm li cas los xij, raws li cov chips loj thiab silicon wafer loj dhau los ua qhov loj thiab loj dua, thiab cov kab dav yuav zoo dua thiab zoo dua, 1x raug ua rau nws nyuaj zuj zus los ua lub npog ntsej muag nrog cov qauv ntau lawm thiab qhov tseeb ntawm qhov chaw.
Yog li ntawd, nyob rau hauv lub lig 1970s, ib tug txo magnification, thaiv exposure tshuab tau los ua. Cov qauv nti yog raug rau ntawm silicon wafer ib qho los ntawm ib qho, raws li pom hauv daim duab 7.2 (b). Yog li ntawd, qhov kev cuam tshuam no nrog kev txo qis yog hu ua kauj ruam-thiab-rov ua dua los yog stepper.
Txawm li cas los xij, raws li cov nti loj thiab silicon wafer loj dua thiab cov kab dav tswj tau ua nruj dua, txawm tias lub peev xwm ntawm cov stepper tsis tuaj yeem ua tau raws li qhov xav tau. Kev daws qhov tsis sib xws ntawm qhov kev thov no thiab cov cuab yeej siv tam sim no ncaj qha coj mus rau kev yug me nyuam ntawm cov kauj ruam-thiab-scan raug tshuab, raws li qhia hauv daim duab 7.2 (c). Cov cuab yeej no yog ib qho hybrid uas sib xyaw ua ke ntawm qhov zoo ntawm lub tshuab luam ntawv puv puv wafer thaum ntxov thiab tom qab cov kauj ruam-thiab-rov ua dua lub tshuab raug: lub npog ntsej muag raug tshuaj xyuas thiab ua tiav tsis yog qhov projected ib zaug, thiab tag nrho cov silicon wafer kuj raug rau hauv. thaiv. Cov cuab yeej no hloov cov teeb meem kho qhov muag mus rau siab kho qhov chaw thiab tswj. Cov cuab yeej no tau siv los ntawm kev lag luam rau niaj hnub no, tshwj xeeb tshaj yog nyob rau hauv kev tsim cov semiconductor chips ntawm 65nm thiab hauv qab no cov thev naus laus zis.
Lub tshuab lithography tseem ceeb hauv ntiaj teb yog ASML hauv Netherlands, Nikon thiab Canon hauv Nyij Pooj, thiab lwm yam tsis muaj qhov loj lithography tshuab manufacturers, xws li Ultrastepper.
Kev tsim khoom ntawm domestic advanced scanning lithography tshuab pib lig. Tom qab 2002, nws yog tsim los ntawm Shanghai Microelectronics Equipment Co., Ltd. (SMEE). Cov tshuab lithography hauv tsev tau tsim los ntawm kev kho cov tshuab lithography thib ob rau nws tus kheej tsim thiab tsim cov tshuab lithography. Lub tshuab lithography tshaj plaws tam sim no nyob rau hauv kev txhim kho yog 193nm SSA600/20 (saib daim duab 7.3). Txawm hais tias tseem muaj qhov sib txawv loj nrog lub ntiaj teb qib siab, nws yuav tsum tau hais tias kev ua tiav tau ua tiav zoo siab. Nws cov lej aperture yog 0.75, tus qauv raug teb yog 26 × 33mm, qhov kev daws teeb meem yog 90nm, qhov tseeb overlay yog 20nm, thiab 300mm ntau lawm muaj peev xwm yog 80 daim ib teev.
Lwm txoj kev hloov cov duab
Nws paub zoo tias ib qho kev taw qhia rau kev txhim kho txuas ntxiv ntawm photolithography yog txo cov wavelength. Txawm li cas los xij, qhov kev siv zog no tau raug cuam tshuam los ntawm cov yam ntxwv xws li kev txhim kho 157nm photoresists, daim npog ntsej muag tiv thaiv zaj duab xis (pellicles) thiab cov khoom ntim ntawm cov khoom siv lens xws li calcium fluoride (
). Txawm li cas los xij, hauv 20 xyoo dhau los, tib neeg tau nqis peev ntau ntawm kev tshawb fawb hauv ultraviolet (EUV) wavelength photolithography. Cov thev naus laus zis no siv 13.5nm ultraviolet lub teeb tawm los ntawm xenon lossis tin plasma tsim los ntawm cov lasers muaj zog lossis cov hluav taws xob tawm siab. Txawm hais tias lub siab daws teeb meem coj los ntawm EUV thev naus laus zis yog qhov txaus nyiam heev, cov thev naus laus zis no kuj muaj ntau yam teeb meem, xws li daim iav tau yooj yim kis los ntawm cov khoom txaws tsim los ntawm cov mem tes, lub teeb ultraviolet huab cua tau yooj yim absorbed (yuav tsum muaj lub kaw lus kom muaj qhov tsis tshua muaj siab. Lub tshuab nqus tsev siab thiab qhov tsawg kawg nkaus ntawm cov tsom iav tsom iav), cov kev cai nruj rau lub npog ntsej muag (tsis muaj qhov tsis xws luag thiab muaj kev cuam tshuam siab), qhov flare tshwm sim los ntawm luv wavelength, cov tshuaj tiv thaiv ceev ntawm photoresist thiab kev daws teeb meem, thiab lwm yam.
Ntxiv nrog rau kev siv lub teeb ci los hloov lub npog ntsej muag, tib neeg tseem tab tom nrhiav lwm txoj hauv kev microlithography, xws li X-ray, nanoimprint, multi-electron beam direct sau, electron beam, ion beam projection, etc.
System parameters ntawm photolithography
Wavelength, naj npawb aperture, duab chaw nruab nrab refractive index
Nws tau hais ua ntej hais tias qhov kev daws teeb meem ntawm qhov sib thooj ntawm qhov sib thooj ntawm qhov sib thooj ntawm qhov sib txawv ntawm qhov sib txawv sai sai vim qhov kev ncua deb ntawm lub npog ntsej muag thiab cov silicon wafer nce. Nyob rau hauv qhov projection exposure method, qhov kev daws teeb meem kho qhov muag yog txiav txim siab los ntawm cov qauv hauv qab no, uas yog,
Ntawm lawv,
sawv cev rau tus proportional coefficient uas characterizes qhov nyuaj ntawm cov txheej txheem photolithography. Feem ntau hais lus,
yog nruab nrab ntawm {{0}}.25 thiab 1.0. Qhov no yog qhov tseeb Rayleigh mis nyuj. Raws li cov qauv no, qhov kev daws teeb meem kho qhov muag yog txiav txim siab los ntawm lub wavelength λ, tus lej aperture NA, thiab cov txheej txheem ntsig txog
. Yog tias koj xav tau luam tawm tus qauv me me, txoj kev siv tuaj yeem ua rau tib lub sijhawm txo qhov raug wavelength, nce tus lej aperture, txo qhov
tus nqi, lossis hloov ib qho ntawm cov yam ntxwv. Hauv seem no, peb yuav xub qhia txog cov txiaj ntsig uas twb muaj lawm ntawm kev txhim kho kev daws teeb meem los ntawm kev txo cov wavelength thiab nce tus lej aperture. Yuav ua li cas txhim kho qhov kev daws teeb meem los ntawm kev txo cov
qhov tseem ceeb nyob rau hauv qhov chaw ntawm qhov ruaj khov wavelength thiab cov lej aperture yuav tau tham tom qab.
Txawm hais tias luv luv wavelength tuaj yeem ua tiav qhov kev daws teeb meem siab, ob peb lwm yam tseem ceeb ntsig txog lub teeb ci yuav tsum tau txiav txim siab, xws li luminous siv (brightness), zaus bandwidth, thiab coherence (coherence yuav piav qhia hauv qab no). Tom qab kev tshuaj ntsuam xyuas, lub teeb hluav taws xob siab mercury tau xaiv los ua lub teeb pom kev zoo vim nws qhov ci ci thiab ntau cov kab ntse ntse. Kev sib txawv ntawm qhov sib txawv wavelengths tuaj yeem xaiv los ntawm kev siv cov ntxaij lim dej ntawm cov wavelength sib txawv. Lub peev xwm los xaiv ib lub wavelength ntawm lub teeb yog ib qho tseem ceeb rau photolithography, vim hais tias ib tug dav stepper yuav tsim chromatic aberration rau non-monochromatic lub teeb, uas ua rau ib tug txo nyob rau hauv cov duab zoo. G kab, H kab, thiab kuv kab siv hauv kev lag luam xa mus rau 436nm, 405nm, thiab 365nm mercury teeb spectra siv los ntawm lub tshuab raug, raws li (saib daim duab 7.4).
Txij li thaum qhov kev daws teeb meem kho qhov muag ntawm I-line stepper tsuas tuaj yeem ncav cuag 0.25μm, qhov kev thov rau kev daws teeb meem siab dua tau thawb qhov cuam tshuam wavelength mus rau luv luv wavelength, xws li Deep UltraViolet (DUV) spectrum ntawm {{3} }nm. Txawm li cas los xij, qhov txuas ntxiv ntawm cov teeb hluav taws xob siab mercury hauv qhov tob ultraviolet tsis yog qhov zoo tagnrho, tsis yog vim qhov siv tsis txaus, tab sis kuj vim tias cov hluav taws xob nyob rau hauv lub voj voog ntev ntev yuav ua rau kub thiab deformation. Feem ntau ultraviolet lasers kuj tsis zoo tagnrho, xws li argon ion lasers, vim hais tias ntau qhov chaw sib koom ua ke yuav ua rau speckle thiab cuam tshuam rau qhov sib xws ntawm lub teeb pom kev zoo. Hauv qhov sib piv, excimer lasers tau raug xaiv los ua lub teeb pom kev zoo rau kev sib sib zog nqus ultraviolet vim lawv cov txiaj ntsig hauv qab no.
(1) Lawv lub zog tso zis siab ua kom muaj txiaj ntsig ntawm lub tshuab lithography;
(2) Lawv spatial incoherence, tsis zoo li lwm yam lasers, tshem tawm speckle;
(3) Cov zis hluav taws xob siab ua rau nws yooj yim los tsim cov photoresists tsim nyog;
(4) Optically, lub peev xwm los tsim qhov sib sib zog nqus ultraviolet tso zis nrog ib tug nqaim zaus (raws li nqaim li ob peb teev) ua rau nws muaj peev xwm tsim high-zoo tag nrho-quartz lithography tshuab lo ntsiab muag.
Yog li ntawd, excimer lasers tau dhau los ua lub ntsiab teeb pom kev zoo ntawm cov kab hluav taws xob sib xyaw ua ke ntawm 0.5μm thiab hauv qab no, thiab daim ntawv tshaj tawm ntxov tshaj plaws tau luam tawm los ntawm Jain li al. Tshwj xeeb, ob lub excimer lasers, krypton fluoride (KrF) nrog lub wavelength ntawm 248nm thiab argon fluoride (ArF) nrog lub wavelength ntawm 193nm, tau qhia tau zoo heev nyob rau hauv cov nqe lus ntawm raug lub zog, bandwidth, beam puab, lub neej thiab kev ntseeg tau. Yog li ntawd, lawv tau dav siv nyob rau hauv qib siab-thiab-scan lithography tshuab, xws li ASML's dual-platform Twinscan XT: 1000H (KrF), Twinscan XT: 1450G (ArF) thiab Nikon's NSR-S210D (KrF), NSR{11 }}F (ArF).
Tau kawg, tib neeg tseem tab tom nrhiav rau lub teeb lub teeb luv luv, xws li 157nm laser tsim los ntawm fluorine molecules
Txawm li cas los xij, vim qhov nyuaj hauv kev tsim cov duab tsim nyog, daim npog tiv thaiv zaj duab xis (pellicles) thiab cov khoom ntim ntawm cov khoom siv lens calcium fluoride (
), 157nm lithography thev naus laus zis tuaj yeem txuas ntxiv cov txheej txheem semiconductor los ntawm ib qho, uas yog, los ntawm 65nm txog 45nm; thaum yav dhau los txoj kev loj hlob ntawm 193nm lithography tshuab txuas ntxiv cov khoom tsim los ntawm 130nm mus rau ob lub nodes: 90nm thiab 65nm, uas ua rau qhov kawg tso tseg ntawm kev siv zog ua lag luam loj ntawm 157nm lithography tshuab. Txoj kev loj hlob ntawm kev raug wavelength nrog cov txheej txheem nodes yog qhia nyob rau hauv daim duab 7.5.
Ntxiv rau qhov ua kom luv luv ntawm qhov raug wavelength, lwm txoj hauv kev los txhim kho kev daws teeb meem yog txhawm rau nce tus lej aperture (NA) ntawm qhov projection / scanning ntaus ntawv.
Qhov twg n sawv cev rau qhov ntsuas qhov cuam tshuam hauv qhov chaw duab, thiab θ sawv cev qhov siab tshaj plaws ib nrab ntawm lub hom phiaj lens hauv qhov chaw duab, raws li pom hauv daim duab 7.6.
Yog tias qhov nruab nrab ntawm qhov chaw duab yog huab cua lossis lub tshuab nqus tsev, nws qhov ntsuas qhov ntsuas tsis zoo nyob ze rau 1.0 lossis 1.0, thiab cov lej aperture yog sinθ. Qhov loj dua lub kaum sab xis ntawm lub hom phiaj lens hauv qhov chaw duab, qhov kev daws teeb meem ntau dua ntawm qhov kho qhov muag. Yog lawm, yog tias qhov kev ncua deb ntawm lub lens thiab silicon wafer tseem tsis hloov, qhov loj dua tus lej aperture, qhov loj ntawm lub lens. Qhov loj ntawm lub lens loj, qhov loj dua qhov kev tsim khoom nyuaj thiab cov qauv ntau dua.
Feem ntau, qhov siab tshaj plaws ua tiav cov lej aperture yog txiav txim siab los ntawm kev tsim khoom thiab tsim cov nqi ntawm lub lens technology. Tam sim no, tus qauv I-line scanning lithography tshuab (ASML's Twinscan XT: 450G) yog nruab nrog lub lens nrog qhov siab tshaj plaws NA ntawm 0.65, uas tuaj yeem paub qhov sib txawv ntawm cov kab ntom ntom ntawm 22{ {11}}nm thiab lub sijhawm spatial ntawm 440nm. Qhov siab tshaj tus lej aperture ntawm krypton fluoride (KrF) wavelength yog 0.93 (ASML's Twinscan XT: 1000H), uas tuaj yeem paub qhov txawv ntawm cov kab ntom ntom ntawm 80nm (160nm spatial lub sijhawm). Lub tshuab ArF siab tshaj plaws lithography muaj tus lej aperture ntawm 0.93 (ASML's Twinscan XT: 1450G), uas tuaj yeem luam 65nm cov kab ntom ntom (120nm spatial lub sijhawm).
Raws li tau hais ua ntej, tus lej aperture tuaj yeem nce ntxiv tsis yog los ntawm kev nce lub kaum sab xis ntawm lub lens hauv qhov chaw duab, tab sis kuj los ntawm kev nce qhov ntsuas qhov ntsuas ntawm qhov chaw duab. Yog tias dej es tsis txhob siv huab cua los sau qhov chaw duab, qhov ntsuas qhov ntsuas ntawm qhov chaw duab yuav raug nce mus rau 1.44 ntawm lub wavelength ntawm 193nm. Qhov no sib npaug rau qhov nce ntawm 0.93 NA hauv huab cua rau 1.34 NA ib zaug. Qhov kev daws teeb meem yog txhim kho los ntawm 30% mus rau 40%. Yog li ntawd, lub sijhawm tshiab ntawm immersion lithography pib nyob rau hauv 2001. Cov kev lag luam siab tshaj plaws immersion scanning lithography tshuab yog ASML's Twinscan NXT: 1950i thiab Nikon's NSR-S610C, raws li qhia hauv Daim duab 7.7 (a) thiab 7.7 (b). Qhov xwm txheej ntawm immersion lithography yuav piav qhia hauv qab no.
Sawv cev ntawm photolithography daws teeb meem
Nws tau hais ua ntej tias qhov kev daws teeb meem photolithography yog txiav txim siab los ntawm tus lej aperture thiab wavelength ntawm lub kaw lus, thiab tau kawg nws muaj feem xyuam rau photolithography daws teeb meem kev txhim kho txoj kev cuam tshuam nrog qhov zoo.
. Tshooj lus no feem ntau qhia txog kev txiav txim siab txog kev daws teeb meem ntawm cov txheej txheem photolithography. Peb paub tias qhov kev daws teeb meem ntawm qhov kho qhov muag tau muab los ntawm Rayleigh cov txheej txheem nto moo. Thaum ob lub ntsiab lus teeb pom kev zoo sib xws nyob ze rau ib leeg, qhov kev ncua deb ntawm lawv qhov chaw mus rau qhov chaw yog sib npaug rau qhov kev ncua deb ntawm tus nqi siab tshaj plaws mus rau thawj qhov tsawg kawg nkaus tus nqi ntawm lub teeb siv ntawm txhua lub teeb pom kev los ntawm cov cuab yeej kho qhov muag, lub tshuab kho qhov muag tsis tuaj yeem paub qhov txawv seb nws yog ob lossis ib qho teeb pom kev zoo, raws li pom hauv daim duab 7.8. Txawm li cas los xij, txawm tias nws ua tau raws li Rayleigh cov txheej txheem, lub teeb siv nyob rau hauv thaj tsam ntawm ob lub ntsiab lus teeb pom kev zoo tseem qis dua tus nqi ncov, nrog qhov sib txawv ntawm li 20%. Rau cov kab teeb pom kev zoo, thaum qhov dav ntawm lub teeb qhov chaw me me infinitely, rau qhov kho qhov muag nrog cov lej aperture ntawm NA thiab lub wavelength ntawm lub teeb pom kev ntawm λ, lub teeb siv hluav taws xob faib rau ntawm daim duab dav hlau yog
Ntawd yog, qhov kev siv lub teeb ncav cuag thawj qhov tsawg kawg nkaus ntawm qhov nruab nrab ntawm daim duab (2NA). I0 sawv cev rau lub teeb ci ntawm qhov nruab nrab ntawm daim duab. Nws tuaj yeem txiav txim siab tias qhov kev ncua deb tsawg kawg uas qhov kev kho qhov muag tuaj yeem daws tau yog λ/(2NA). Piv txwv li, thaum lub wavelength yog 193nm thiab NA yog 1.35 (immersion), qhov tsawg kawg nkaus daws teeb meem ntawm qhov kho qhov muag system yog 71.5nm.
Tau kawg, rau cov txheej txheem photolithography, nws puas txhais tau tias tus qauv nrog lub sijhawm spatial ntawm 71.5nm tuaj yeem luam tawm? Lo lus teb tsis yog. Muaj ob qho laj thawj:
① Cov txheej txheem yuav tsum muaj qee cov npoo thiab cov txheej txheem ntsuas kom ua tau ntau yam;
② Kev lag luam raug raug ntawm txhua lub tshuab thiab khoom siv thiab kev ua tiav ntawm lub tshuab ua haujlwm, kom lub tshuab tuaj yeem luam cov kab ntom ntom ntawm qhov kev daws teeb meem thiab cov qauv cais, thiab yuav tsum txo qis qhov cuam tshuam ntawm qhov seem ntawm cov txheej txheem.
Rau 1.35 NA lithography tshuab, ASML cog lus tias qhov tsawg kawg nkaus spatial lub sij hawm ntawm tus qauv uas yuav ua tau yog 76nm, uas yog, 38nm ntom kab nrog sib npaug sib nrug. Hauv cov txheej txheem photolithography, qhov kev daws teeb meem txwv tsuas yog siv tus nqi xwb. Hauv kev ua haujlwm tiag tiag, peb tsuas yog tham txog qhov loj npaum li cas lub qhov rais txheej txheem nyob rau hauv ib lub sij hawm spatial thiab ib txoj kab dav, thiab seb nws puas txaus rau cov khoom loj. Cov kev txwv uas ua rau lub qhov rais txheej txheem yuav raug tham kom ntxaws hauv Tshooj 7.4. Ntawm no yog ib qho kev qhia luv luv. Feem ntau, cov yam ntxwv uas ua rau lub qhov rais txheej txheem muaj xws li raug hluav taws xob latitude (EL), qhov tob ntawm kev ua kom pom tseeb lossis qhov tob ntawm kev ua kom pom tseeb (DOF), daim npog qhov ncauj qhov yuam kev (MEF), qhov tseeb overlay, linewidth uniformity, thiab lwm yam.
Exposure zog latitude hais txog qhov siab tshaj plaws tso cai sib txawv ntawm lub zog raug nyob rau hauv qhov tso cai ntawm kab dav variation. Piv txwv li, rau ib txoj kab nrog kab dav ntawm 90nm, kab dav hloov pauv nrog lub zog los ntawm 3nm / mJ, thiab qhov kev tso cai ntawm kab dav sib txawv yog ± 9nm, tom qab ntawd qhov kev tso cai ntawm qhov sib txawv ntawm lub zog sib txawv yog 9 × 2 / { {5}}mJ. Yog tias qhov hluav taws xob raug yog 30mJ, lub zog latitude yog 20% piv rau lub zog raug.
Qhov tob ntawm kev tsom xam feem ntau muaj feem xyuam nrog kev ua haujlwm ntawm kev ua kom pom tseeb ntawm lub tshuab lithography. Piv txwv li, kev tsom xam tswj qhov tseeb ntawm 193nm lithography tshuab, suav nrog kev ruaj ntseg ntawm lub tshuab focal dav hlau, qhov chaw curvature ntawm lub lens, astigmatism, leveling raug, thiab flatness ntawm silicon wafer platform, yog 120nm. Tom qab ntawd qhov tsawg kawg nkaus ntawm kev ua kom pom tseeb ntawm cov txheej txheem uas tuaj yeem ua tau loj yuav tsum siab dua 120nm. Yog tias qhov cuam tshuam ntawm lwm cov txheej txheem, xws li tshuaj-mechanical planarization, ntxiv, qhov tsawg kawg nkaus ntawm kev tsom xam yuav tsum tau txhim kho, xws li 200nm. Ntawm chav kawm, raws li yuav tau tham tom qab, kev txhim kho ntawm qhov tob ntawm kev tsom xam tej zaum yuav yog ntawm cov nuj nqis ntawm lub zog margin.
Lub npog ntsej muag yuam kev (MEF) txhais tau tias yog qhov sib txawv ntawm qhov sib txawv ntawm silicon wafer kab dav vim yog kab dav sib txawv ntawm daim npog ntsej muag mus rau qhov sib txawv ntawm daim npog ntsej muag, raws li qhia hauv cov mis (7-5).
Nquag, MEF ze rau lossis sib npaug rau 1.0. Txawm li cas los xij, thaum lub sij hawm spatial ntawm tus qauv mus txog qhov kev txwv tsis pub tshaj, MEF yuav nce sai. Loj dhau qhov ua yuam kev yuav ua rau cov kab dav sib xws ntawm silicon wafer kom tsis zoo. Los yog, sib raug rau cov kab dav dav uniformity yuav tsum tau, lub npog ntsej muag kab dav uniformity siab dhau.
Overlay raug feem ntau txiav txim siab los ntawm cov kauj ruam, scanning synchronization raug, tswj qhov kub thiab txias, lens aberration, thiab aberration stability ntawm lub platform txav ntawm lub tshuab lithography. Tau kawg, qhov tseeb overlay kuj nyob ntawm qhov kev lees paub thiab kev nyeem ntawv qhov tseeb ntawm lub cim overlay, kev cuam tshuam ntawm cov txheej txheem ntawm lub cim overlay, deformation ntawm cov txheej txheem ntawm silicon wafer (xws li ntau yam txheej txheem cua sov, txheej txheem annealing), thiab lwm yam. Niaj hnub nimno lithography tshuab stepping tuaj yeem them nyiaj rau qhov kev nthuav dav ntawm silicon wafer, thiab tseem tuaj yeem them nyiaj rau qhov tsis sib xws ntawm cov silicon wafer, xws li "daim phiaj phiaj xwm" GridMapper software launched los ntawm ASML. Nws tuaj yeem kho qhov tsis sib xws ntawm cov kab sib chaws uas tsis yog-linear silicon wafer raug.
Kab dav uniformity yog muab faib ua ob pawg: uniformity nyob rau hauv qhov chaw raug (intra-field) thiab uniformity ntawm raug cheeb tsam (inter-field).
Kab dav uniformity nyob rau hauv lub cheeb tsam raug yog tsuas yog txiav txim los ntawm daim npog qhov ncauj kab dav uniformity (hloov los ntawm daim npog qhov ncauj qhov yuam kev), lub zog stability (thaum lub sij hawm scanning), illumination uniformity nyob rau hauv lub scanning slit, tsom / leveling uniformity rau txhua qhov chaw nyob rau hauv qhov chaw raug, lens aberration (xws li coma, astigmatism), scanning synchronization raug yuam kev (tsiv Standard Deviation, MSD), thiab lwm yam.
Kab dav uniformity ntawm cov cheeb tsam raug yog tsuas yog txiav txim los ntawm illumination zog stability, uniformity ntawm silicon wafer substrate zaj duab xis thickness faib rau ntawm silicon wafer nto (tsuas yog vim uniformity ntawm kua nplaum txheej thiab uniformity ntawm zaj duab xis thickness coj los ntawm lwm yam txheej txheem), flatness ntawm silicon wafer. nto, uniformity ntawm developer-related ci, uniformity ntawm developer spraying, thiab lwm yam.
Photolithography txheej txheem ntws
Lub hauv paus 8- cov txheej txheem photolithography ntws yog qhia hauv daim duab 7.9.
kauj ruam 01-HMDS nto kho
kauj ruam 02-Gluing
kauj ruam 03-Pre-exposure ci
kauj ruam 04-Txoj kev sib tw thiab raug
kauj ruam 05-Post-exposure ci
kauj ruam 06-Kev loj hlob
kauj ruam 07-Post-development ci
kauj ruam 08-Kev ntsuas
1. Gas silicon wafer nto pretreatment
Ua ntej photolithography, silicon wafer yuav raug ntxuav thiab deionized dej yaug kom tshem tawm cov kab mob. Tom qab ntxuav, qhov saum npoo ntawm silicon wafer yuav tsum tau hydrophobized los txhim kho qhov adhesion ntawm silicon wafer nto thiab photoresist (feem ntau yog hydrophobic). Kev kho hydrophobic siv cov khoom hu ua hexamethyldisilazane, nrog cov mis molecular ntawm (CH₃)3SiNHSi(CH₃)₃, Lub vapor ntawm hexamethyldisilazane (HMDS) yog tsim. Cov roj pretreatment no zoo ib yam li kev siv cov tshuaj tsuag primer rau ntawm ntoo thiab yas ua ntej pleev xim. Lub luag hauj lwm ntawm hexamethyldisilazane yog los hloov cov hydrophilic hydroxyl (OH) nyob rau saum npoo ntawm silicon wafer nrog hydrophobic hydroxyl (OH) los ntawm cov tshuaj tiv thaiv.OSi(CH₃)₃.To ua kom tiav lub hom phiaj ntawm kev kho ua ntej.
Qhov kub ntawm cov roj pretreatment tswj ntawm 200-250 degree , thiab lub sij hawm feem ntau yog 30s. Gas pretreatment ntaus ntawv txuas nrog lub wafer khiav rau photoresist ua, thiab nws cov qauv yooj yim yog qhia nyob rau hauv daim duab 7.10.
2. Spin-coated photoresist, anti-reflective txheej
Tom qab roj pretreatment, photoresist yuav tsum tau coated rau saum npoo ntawm silicon wafer. Txoj kev siv txheej txheej dav tshaj plaws yog txoj kev tig txheej txheej. Lub photoresist (kwv yees li ob peb milliliters) yog thawj zaug thauj mus rau qhov chaw ntawm silicon wafer los ntawm lub raj xa dej, thiab tom qab ntawd cov silicon wafer yuav tig thiab maj nrawm kom txog thaum nws ruaj khov ntawm qee qhov ceev (qhov ceev txiav txim siab lub thickness ntawm cov kua nplaum, thiab lub thickness yog inversely proportional rau square root ntawm ceev). Thaum lub silicon wafer nres, nws qhov chaw yog qhov pib qhuav thiab lub thickness yog ruaj khov ntawm qhov loj me me. Lub uniformity ntawm txheej thickness yuav tsum nyob rau hauv ± 20Å ("Å, pronounced "angstrom", yog ib chav tsev ntawm qhov ntev ntawm particle physics. 1Å yog sib npaug rau
m, uas yog ib feem kaum ntawm ib nanometer) ntawm 45nm lossis ntau dua cov tshuab thev naus laus zis. Feem ntau, muaj peb yam tseem ceeb ntawm photoresist, organic resin, tshuaj hnyav, thiab photosensitive compound (PAC).
Cov ncauj lus kom ntxaws photoresist yuav tau tham hauv tshooj ntawm photoresist. Tshooj lus no tsuas yog tham txog cov dej dynamics. txheej txheej txheej yog muab faib ua peb kauj ruam:
① Thauj ntawm photoresist;
② Ceev cov kev sib hloov ntawm silicon wafer mus rau qhov kawg ceev;
③ Tig ntawm qhov ceev kom txog thaum lub thickness stabilizes ntawm tus nqi preset;
Qhov kawg photoresist thickness yog ncaj qha ntsig txog photoresist viscosity thiab qhov kawg kev sib hloov ceev. Lub viscosity ntawm photoresist tuaj yeem hloov kho los ntawm kev nce lossis txo cov tshuaj hnyav. Spin coating fluid mechanics tau ua tib zoo kawm.
Cov kev xav tau siab rau photoresist thickness uniformity tuaj yeem ua tiav los ntawm kev tswj xyuas tag nrho cov hauv qab no:
① Photoresist kub;
② Ambient kub;
③ Silicon wafer kub;
④ Cov dej ntws tawm thiab siab ntawm cov txheej txheem txheej;
Yuav ua li cas txo cov txheej txheem cuam tshuam yog lwm qhov kev sib tw. Kev xyaum qhia tau hais tias kev siv cov txheej txheem hauv qab no tuaj yeem txo qhov tshwm sim ntawm qhov tsis xws luag.
(1) Lub photoresist nws tus kheej yuav tsum huv si thiab tsis muaj ib qho teeb meem. Ua ntej txheej txheej, nws yuav tsum yog siv cov txheej txheem pom, thiab qhov pore loj ntawm lub lim yuav tsum ua tau raws li qhov yuav tsum tau ua ntawm lub tshuab node.
(2) Lub photoresist nws tus kheej yuav tsum tsis txhob muaj cov huab cua sib xyaw, vim cov npuas yuav ua rau cov duab tsis zoo. Cov npuas coj zoo ib yam li cov khoom.
(3) Kev tsim ntawm lub tais txheej yuav tsum tiv thaiv kev sib tsoo ntawm cov ejected photoresist.
(4) Lub twj tso kua mis rau xa cov photoresist yuav tsum tau tsim kom muaj peev xwm nqus rov qab tom qab txhua tus xa khoom ntawm photoresist. Kev ua haujlwm ntawm qhov nqus rov qab yog nqus cov photoresist ntau dhau los ntawm lub nozzle rov qab rau hauv cov raj xa dej kom tsis txhob muaj ntau tshaj photoresist dripping ntawm silicon wafer los yog ntau tshaj photoresist qhuav thiab ua rau granular defects thaum lub sij hawm xa khoom tom ntej. Kev nqus rov qab ua haujlwm yuav tsum tau kho kom tsis txhob muaj cua ntau dhau los ntawm cov kav dej.
(5) Wafer ntug debonding (Edge Cov kuab tshuaj siv nyob rau hauv lub Bead Tshem Tawm (EBR) txheej txheem yuav tsum tau tswj kom zoo. Thaum lub sij hawm spin txheej txheej txheem ntawm silicon wafers, lub photoresist yuav ntws mus rau ntawm ntug ntawm silicon wafer thiab los ntawm ntug. lub silicon wafer rau sab nraum qab ntawm silicon wafer vim yog lub zog centrifugal Ib lub voj voog ntawm cov hlaws zoo li cov duab hluav taws xob residue yuav tsim ntawm ntug ntawm silicon wafer vim nws qhov nro, raws li pom hauv daim duab 7.11 . photoresist residue nyob rau sab nraum qab ntawm silicon wafer yuav lo rau silicon wafer platform (wafer chuck), ua rau tsis zoo adsorption ntawm silicon wafer, ua rau raug defocus, thiab nce overlay yuam kev txheej txheej. Kev ua haujlwm ntawm kev tshem cov photoresist ntawm ib qho kev ncua deb ntawm ntug ntawm silicon wafer yog ua tiav los ntawm rotating silicon wafer ntawm ntug ntawm silicon wafer (ib lub nozzle rau sab saum toj thiab ib qho hauv qab, thiab txoj hauj lwm ntawm lub nozzle los ntawm ntug ntawm silicon wafer yog adjustable).
(6) Tom qab ua tib zoo xam, nws tau pom tias li ntawm 90% mus rau 99% ntawm photoresist tau spun tawm ntawm silicon wafer thiab nkim. Cov tib neeg tau sim ua kom cov silicon wafer ua ntej tig lub photoresist ntawm silicon wafer siv cov tshuaj hnyav hu ua propylene glycol methyl ether acetate (molecular formula CH₃COOCH(CH₃)CH₃OCH₃), PGMEA). Txoj kev no hu ua resist reduction coating (RRC). Txawm li cas los xij, yog tias txoj kev no siv tsis raug, cov teeb meem yuav tshwm sim. Qhov tsis xws luag yuav cuam tshuam rau cov tshuaj lom neeg ntawm RRC-photoresist interface thiab kev sib kis ntawm RRC hnyav los ntawm ammonia hauv huab cua.
(7) Ua kom lub siab tso tawm ntawm tus tsim tawm lossis tus tsim tawm module kom tiv thaiv kev sib tsoo rov qab ntawm cov tee me me ntawm tus tsim tawm thaum lub sijhawm tsim kho thaum lub silicon wafer tig.
Txij li thaum lub viscosity ntawm photoresist hloov nrog kub, txawv thicknesses yuav tau los ntawm txhob txwm hloov qhov kub ntawm silicon wafer los yog photoresist. Yog tias qhov ntsuas kub sib txawv tau teeb tsa hauv ntau qhov chaw ntawm silicon wafer, qhov sib txawv photoresist thicknesses tuaj yeem tau txais ntawm silicon wafer. Qhov zoo tshaj plaws photoresist thickness tuaj yeem txiav txim siab los ntawm txoj cai ntawm kab dav thiab photoresist thickness (swing nkhaus) kom txuag tau silicon wafers, tshuab lub sijhawm thiab cov ntaub ntawv. Kev sib tham ntawm viav vias nkhaus yuav tau tham hauv tshooj tom ntej. Cov txheej txheem thiab lub hauv paus ntsiab lus ntawm spin txheej ntawm anti-reflective txheej yog tib yam.
3. Ua ntej ci ci
Tom qab lub photoresist yog spin-coated rau saum npoo ntawm silicon wafer, nws yuav tsum tau ci. Lub hom phiaj ntawm kev ci yog tshem tawm yuav luag tag nrho cov kuab tshuaj. Qhov ci no yog hu ua "pre-exposure baking" los yog "pre-baking" vim nws tau ua ua ntej raug. Pre-baking txhim kho qhov adhesion ntawm photoresist, txhim kho cov uniformity ntawm photoresist, thiab tswj cov kab dav uniformity thaum lub sij hawm etching txheej txheem. Nyob rau hauv chemically amplified photoresist hais nyob rau hauv Tshooj 6.3, pre-baking kuj yuav siv tau los hloov lub diffusion ntev ntawm lub photoacid rau ib tug tej yam uas yuav tsum tau kho qhov tsis ntawm lub qhov rais txheej txheem. Qhov kub thiab lub sijhawm ua ntej ci yog 90-100 degree, txog 30s. Tom qab ua ntej ci, silicon wafer yuav raug txav los ntawm lub phaj kub uas siv rau ci rau lub phaj txias kom rov qab mus rau chav sov hauv kev npaj rau cov kauj ruam raug.
4. Kev sib tw thiab raug
Cov kauj ruam tom qab ua ntej ci yog kev sib tw thiab raug. Nyob rau hauv txoj kev pom kev pom, lub npog ntsej muag raug hloov mus rau qhov chaw kwv yees ua ntej ntawm silicon wafer, lossis mus rau txoj haujlwm kom zoo nrog rau cov qauv uas twb muaj lawm ntawm silicon wafer, thiab tom qab ntawd lub lens hloov nws cov qauv mus rau silicon wafer los ntawm photolithography. Rau qhov sib thooj lossis kev sib cuag, tus qauv ntawm lub npog ntsej muag yuav raug ncaj qha rau ntawm silicon wafer los ntawm lub teeb ci ultraviolet.
Rau thawj txheej ntawm cov qauv, tej zaum yuav tsis muaj cov qauv ntawm silicon wafer, thiab lub tshuab photolithography txav lub npog ntsej muag mus rau qhov predefined (chip txawv txoj kev) kwv yees txoj hauj lwm ntawm silicon wafer (nyob ntawm seb qhov kev tso kawm ntawm qhov tseeb ntawm silicon wafer. ntawm photolithography tshuab platform, feem ntau nyob ib ncig ntawm 10 mus rau 30 μm).
Rau cov txheej txheem thib ob thiab cov qauv tom ntej, lub tshuab photolithography yuav tsum tau ua kom tiav cov txheej txheem kev sib dhos uas tau tso tseg los ntawm cov txheej txheem dhau los ua rau overprint lub npog ntsej muag ntawm txheej txheej ntawm cov qauv uas twb muaj lawm ntawm txheej dhau los. Qhov tseeb overlay no feem ntau yog 25% mus rau 30% ntawm tus qauv yam tsawg kawg nkaus. Piv txwv li, hauv 90nm thev naus laus zis, qhov tseeb overlay feem ntau yog 22 txog 28nm (3 npaug ntawm tus qauv sib txawv). Thaum qhov kev sib raug zoo raug ua tau raws li qhov yuav tsum tau muaj, kev nthuav tawm pib. Lub teeb lub zog activates lub teeb-sensitive Cheebtsam nyob rau hauv lub photoresist thiab pib cov tshuaj tiv thaiv photochemical. Cov cim tseem ceeb rau kev ntsuas qhov zoo ntawm photolithography feem ntau yog qhov kev daws teeb meem thiab qhov sib xws ntawm qhov tseem ceeb ntawm qhov ntev (CD), qhov tseeb overlay, thiab tus naj npawb ntawm cov khoom thiab qhov tsis xws luag.
Lub ntsiab lus tseem ceeb ntawm qhov tseeb overlay yog hais txog qhov tseeb ntawm kev sib raug zoo (3σ) ntawm cov duab ntawm ob txheej txheem photolithography. Yog tias qhov sib txawv ntawm qhov sib txawv loj dhau, nws yuav cuam tshuam ncaj qha rau cov khoom lag luam. Rau cov tshuab photolithography high-end, cov khoom siv dav dav yuav muab ob qho txiaj ntsig rau qhov tseeb overlay, ib qho yog ob lub sij hawm overlay yuam kev ntawm ib lub tshuab nws tus kheej, thiab lwm yam yog qhov yuam kev overlay ntawm ob lub cuab yeej (cov khoom sib txawv).
5. Tom qab kis tau ci
Tom qab ua tiav qhov raug, lub photoresist yuav tsum tau ci dua. Vim tias qhov ci no yog tom qab kis tau, nws yog hu ua "post-exposure baking", abbreviated as post-exposure baking (PEB). Lub hom phiaj ntawm tom qab ci yog ua kom tiav cov tshuaj tiv thaiv photochemical los ntawm cua sov. Cov photosensitive Cheebtsam tsim thaum lub sij hawm raug cov txheej txheem yuav diffuse nyob rau hauv qhov kev txiav txim ntawm cua sov thiab reacts chemically nrog lub photoresist, hloov cov photoresist cov ntaub ntawv uas yuav luag insoluble nyob rau hauv tus tsim tawm kua rau hauv cov khoom uas yog soluble nyob rau hauv tus tsim tawm kua, tsim qauv uas yog soluble. nyob rau hauv lub developer kua thiab insoluble nyob rau hauv lub developer kua nyob rau hauv lub photoresist zaj duab xis.
Txij li cov qauv no zoo ib yam nrog cov qauv ntawm lub npog ntsej muag, tab sis tsis tshwm sim, lawv tseem hu ua "cov duab latent". Rau chemically amplified photoresists, ntau ci kub los yog ntau lub sij hawm ci yuav ua rau ntau tshaj diffusion ntawm photoacids (catalysts ntawm photochemical cov tshuaj tiv thaiv), ua rau lub qub duab sib piv, yog li txo cov uniformity ntawm lub qhov rais txheej txheem thiab kab dav. Kev sib tham ntxaws yuav raug ua nyob rau hauv tshooj tom ntej. Txhawm rau kom pom cov duab latent tiag tiag, kev txhim kho yuav tsum tau ua.
6. Kev loj hlob
Tom qab ua tiav tom qab ci, silicon wafer yuav nkag mus rau theem kev txhim kho. Txij li thaum lub photoresist tom qab photochemical cov tshuaj tiv thaiv yog acidic, muaj zog alkaline tov yog siv raws li tus tsim tawm. Feem ntau, 2.38% tetramethylammonium hydroxide aqueous tov (TMAH) nrog cov mis molecular ntawm (CH₃)₄NOH yog siv. Tom qab cov yeeb yaj kiab photoresist tau dhau los ntawm cov txheej txheem kev txhim kho, cov cheeb tsam raug tshem tawm los ntawm tus tsim tawm, thiab cov qauv ntawm lub npog ntsej muag tau tso tawm rau ntawm daim duab photoresist ntawm silicon wafer nyob rau hauv daim ntawv ntawm concave thiab convex duab nrog los yog tsis muaj photoresist. Txoj kev txhim kho feem ntau muaj cov kauj ruam hauv qab no:
(1) Pre-spray (pre-ntub): tsuag me ntsis dej deionized (DI dej) rau ntawm qhov chaw ntawm silicon wafer los txhim kho cov adhesion ntawm tus tsim tawm ntawm qhov chaw ntawm silicon wafer.
(2) Developer dispense (developer dispense): xa tus tsim tawm mus rau saum npoo ntawm silicon wafer. Txhawm rau ua kom txhua qhov chaw ntawm silicon wafer nto tiv nrog tib tus nqi ntawm tus tsim tawm kom ntau li ntau tau, tus tsim tawm dispense tau tsim cov hauv qab no. Piv txwv li, siv E2 nozzles, LD nozzles, thiab lwm yam.
(3) Developer nto nyob (puddle): Tom qab tus tsim tawm yog txau, nws yuav tsum tau nyob rau saum npoo ntawm silicon wafer rau ib lub sij hawm ntawm lub sij hawm, feem ntau ntawm kaum vib nas this mus rau ib los yog ob feeb, thiaj li yuav tso cai rau tus tsim tawm kom tag nrho cov teeb meem nrog photoresist.
(4) Kev tshem tawm thiab yaug tus tsim tawm: Tom qab tus tsim tawm tau tso tseg, tus tsim tawm yuav raug muab pov tseg thiab cov dej deionized yuav muab txau rau ntawm qhov chaw ntawm silicon wafer kom tshem tawm cov seem tsim tawm thiab cov seem seem ntawm cov khoom siv photoresist.
(5) Spin qhuav: Lub silicon wafer yog tig mus rau ib qho kev kub ceev kom tig tawm cov dej deionized ntawm qhov chaw.
7. Tom qab kev txhim kho ci, tawv zaj duab xis ci
Tom qab kev txhim kho, txij li thaum silicon wafer raug dej, lub photoresist yuav nqus tau qee cov dej, uas tsis zoo rau cov txheej txheem tom ntej xws li ntub dej etching. Yog li ntawd, cov zaj duab xis tawv ci yuav tsum tau tshem tawm cov dej ntau dhau los ntawm photoresist. Txij li feem ntau etching tam sim no siv plasma etching, tseem hu ua "dry etching", hard film ci tau raug tshem tawm hauv ntau cov txheej txheem.
8. Kev ntsuas
Tom qab qhov raug ua tiav, qhov tseem ceeb ntawm qhov loj me (Critical Dimension, CD luv luv) tsim los ntawm lithography thiab qhov tseeb overlay yuav tsum tau ntsuas (metrology). Qhov loj me me feem ntau yog ntsuas siv lub tshuab ntsuas hluav taws xob ntsuas hluav taws xob, thaum qhov tseeb ntawm qhov sib tshooj yog ntsuas los ntawm lub tshuab ntsuas qhov muag thiab tus nqi sib txuas ntawm cov duab ntes (CCD). Qhov laj thawj ntawm kev siv lub tshuab ntsuas hluav taws xob ntsuas hluav taws xob yog tias txoj kab dav dav hauv cov txheej txheem semiconductor feem ntau me dua lub wavelength ntawm pom lub teeb, xws li 400 mus rau 700nm, thiab cov hluav taws xob sib npaug wavelength ntawm electron microscope yog txiav txim siab los ntawm qhov nrawm ntawm qhov hluav taws xob. electron. Raws li cov hauv paus ntsiab lus ntawm quantum mechanics, De Broglie wavelength ntawm electron yog
Qhov twg h (6.626 × 10-³⁴Js) yog Planck qhov tas li, m (9.1 × 10-³¹kg) yog qhov loj ntawm cov hluav taws xob hauv lub tshuab nqus tsev, thiab v yog qhov nrawm ntawm electron. Yog hais tias qhov acceleration voltage yog V, lub de Broglie wavelength ntawm electron tuaj yeem sau ua
Qhov twg q (1.609 × 10-19c) yog tus nqi ntawm electron. Hloov cov lej lej, qhov sib npaug (7-7) tuaj yeem kwv yees li sau ua
Yog tias qhov ntsuas hluav taws xob nrawm yog 300V, lub wavelength ntawm electron yog 0.07nm, uas yog txaus rau ntsuas kab dav. Hauv kev ua haujlwm tiag tiag, qhov kev daws teeb meem ntawm lub tshuab ntsuas hluav taws xob yog txiav txim siab los ntawm ntau qhov tawg ntawm cov kab hluav taws xob hauv cov khoom siv thiab qhov aberration ntawm lub lens electron. Feem ntau, qhov kev daws teeb meem ntawm lub tshuab ntsuas hluav taws xob yog kaum ntawm nanometers, thiab qhov yuam kev ntawm kev ntsuas kab qhov ntev yog li 1 txog 3nm. Txawm hais tias qhov tseeb overlay tau mus txog qib nanometer, txij li kev ntsuas ntawm overlay tsuas yog xav tau lub peev xwm los txiav txim siab qhov chaw nruab nrab ntawm cov kab tuab, lub tshuab ntsuas qhov muag tuaj yeem siv los ntsuas qhov tseeb overlay.
Daim duab 7.12 (a) yog ib qho screenshot ntawm qhov ntsuas qhov loj me los ntawm lub tshuab ntsuas hluav taws xob scanning. Cov kab dawb ob kab thiab cov xub txheeb ze hauv daim duab sawv cev rau lub hom phiaj loj. Cov duab sib piv ntawm lub tshuab ntsuas hluav taws xob scanning yog tsim los ntawm emission thiab sau ntawm cov khoom siv hluav taws xob thib ob uas tsim los ntawm electron bombardment. Nws tuaj yeem pom tias cov khoom siv hluav taws xob thib ob tuaj yeem sau tau ntawm ntug ntawm kab. Nyob rau hauv txoj cai, qhov ntau electrons sau, qhov ntau yog qhov ntsuas. Txawm li cas los xij, txij li qhov cuam tshuam ntawm lub teeb hluav taws xob ntawm lub photoresist tsis tuaj yeem tsis quav ntsej, photoresist yuav poob tom qab electron beam irradiation, tshwj xeeb tshaj yog 193nm photoresist. Yog li nws tseem ceeb heev los tsim kom muaj qhov sib npaug ntawm qhov ntsuas thiab qhov cuam tshuam tsawg kawg nkaus.
Daim duab 7.12 (b) yog ib daim duab schematic ntawm kev ntsuas overlay, nyob rau hauv uas cov kab thickness feem ntau yog 1 mus rau 3 μm, sab thav duab sab ntev yog feem ntau 20 mus rau 30 μm, thiab sab hauv ncej ntev yog feem ntau 10 mus rau 20 μm. . Nyob rau hauv daim duab no, cov xim sib txawv los yog qhov sib txawv uas tshwm sim los ntawm sab hauv thiab sab nrauv yog vim qhov sib txawv ntawm cov xim thiab qhov sib txawv ntawm cov teeb pom kev zoo los ntawm cov thicknesses sib txawv ntawm cov txheej txheem nyias nyias. Kev ntsuas ntawm overlay yog ua tiav los ntawm kev txiav txim siab qhov sib txawv ntawm qhov chaw nruab nrab ntawm tus ncej puab thiab qhov chaw nruab nrab ntawm lub thav duab sab nrauv. Kev xyaum tau ua pov thawj tias ntev npaum li lub teeb liab txaus siv, txawm tias lub tshuab ntsuas qhov muag tuaj yeem ua tiav qhov ntsuas qhov tseeb ntawm li 1 nm.
Lithography txheej txheem qhov rais thiab qauv kev ntsuam xyuas kev ncaj ncees
Tawm lub zog npoo, normalized duab logarithmic nqes hav (NILS)
Hauv Tshooj 2, nws tau hais tias qhov cuam tshuam lub zog ntawm cov npoo (EL) yog hais txog qhov siab tshaj plaws tso cai sib txawv ntawm lub zog raug nyob rau hauv qhov kev tso cai ntawm kab dav sib txawv. Nws yog ib qho tseem ceeb parameter rau kev ntsuas cov txheej txheem lithography.
Daim duab 7.13 (a) qhia qhov kev hloov pauv ntawm cov qauv lithography nrog lub zog raug thiab focal ntev.
Daim duab 7.13 (b) qhia txog cov qauv kev faib tawm ob sab nrog lub zog sib txawv thiab qhov ntev focal ntev nthuav tawm ntawm silicon wafer. Nws zoo li lub matrix thiab tseem hu ua Focus-Exposure Matrix (FEM).
Cov matrix no yog siv los ntsuas lub qhov rais txheej txheem ntawm cov txheej txheem photolithography ntawm ib lossis ob peb tus qauv, xws li lub zog npoo thiab qhov tob tob. Yog tias cov qauv kuaj tshwj xeeb ntawm lub npog ntsej muag raug ntxiv, Focus-Energy Matrix kuj tseem tuaj yeem ntsuas lwm yam kev ua haujlwm tsis muaj feem cuam tshuam nrog cov txheej txheem thiab cov khoom siv, xws li ntau yam aberrations ntawm lithography tshuab lens, stray light (flare), daim npog qhov ncauj yuam kev, photoacid diffusion. ntev ntawm photoresist, rhiab heev ntawm photoresist, raug raug ntawm lub npog ntsej muag, thiab lwm yam.
Nyob rau hauv daim duab 7.13 (a), cov duab grey sawv cev rau qhov sib txawv ntawm cov morphology ntawm photoresist (zoo photoresist) tom qab raug thiab kev loj hlob. Raws li cov hluav taws xob raug hluav taws xob txuas ntxiv mus, cov kab dav yuav me dua thiab me dua. Raws li qhov focal ntev hloov, ntsug morphology ntawm photoresist kuj hloov. Cia peb pib tham txog qhov hloov pauv nrog lub zog. Yog hais tias lub focal ntev raug xaiv raws li -0.1μm, uas yog, lub phiaj xwm focal dav hlau yog 0.1μm hauv qab saum toj ntawm photoresist. Yog hais tias txoj kab dav yog ntsuas raws li nws hloov nrog lub zog, qhov nkhaus raws li qhia hauv daim duab 7.14 tuaj yeem tau.
Yog tias peb xaiv tag nrho CD kam rau ua ntawm kab dav li ± 10% ntawm kab dav ntawm 90nm, uas yog, 18nm, thiab txoj kab nqes ntawm kab dav hloov nrog lub zog raug yog 6.5nm / (mJ / cm²), thiab qhov pom kev pom lub zog yog 20 (mJ / cm²), ces lub zog paj EL yog 18/6.5/20=13.8%.
Puas yog txaus? Cov lus nug no muaj feem xyuam nrog rau yam xws li lub zog ntawm lub tshuab lithography, lub peev xwm ntawm kev tswj cov txheej txheem, thiab cov kev xav tau ntawm cov cuab yeej rau kab dav. Lub zog npoo kuj tseem cuam tshuam nrog lub photoresist lub peev xwm los khaws cov duab spatial. Feem ntau hais lus, ntawm 90nm, 65nm, 45nm thiab 32nm nodes, EL yuav tsum tau rau lub rooj vag txheej lithography yog 15% mus rau 20%, thiab EL yuav tsum tau rau hlau thaiv txheej yog li 13% mus rau 15%.
Lub zog npoo kuj tseem cuam tshuam ncaj qha rau cov duab sib piv, tab sis cov duab ntawm no tsis yog cov duab spatial los ntawm lub lens, tab sis "cov duab latent" tom qab cov tshuaj tiv thaiv photochemical ntawm photoresist. Kev nqus ntawm lub teeb los ntawm photoresist thiab qhov tshwm sim ntawm cov tshuaj tiv thaiv photochemical yuav tsum tau diffusion ntawm lub teeb-sensitive Cheebtsam hauv photoresist zaj duab xis. Qhov diffusion xav tau rau qhov tshuaj tiv thaiv photochemical no yuav txo qhov sib piv ntawm daim duab. Contrast yog txhais raws li
Ntawm lawv, U yog qhov sib npaug ntawm lub teeb siv ntawm "cov duab latent" (qhov tseeb qhov ceev ntawm lub teeb-sensitive tivthaiv).
Rau cov kab ntom ntom, yog tias lub sijhawm spatial P tsawg dua λ / NA, ces nws cov duab spatial sib npaug lub teeb siv U(x) yuav tsum yog sine yoj, raws li qhia hauv daim duab 7.15, uas tuaj yeem sau tau raws li
Raws li cov ntsiab lus ntawm EL, ua ke nrog cov qauv (7-10), raws li qhia hauv daim duab 7.16, EL tuaj yeem sau tau raws li cov lus hauv qab no, uas yog,
Rau cov kab sib npaug thiab qhov chaw, CD=P/2. Muaj ib tug ntau concise thiab intuitive qhia, uas yog
Ntawd yog, yog tias dCD siv dav dav 10% CD, ces qhov sib piv yog kwv yees li 3.2 npaug ntawm EL. Txoj kab nqes hauv cov qauv (7-11) yog
Nws tseem hu ua duab log nqes hav (ILS). Vim nws txoj kev sib raug zoo nrog cov duab zoo sib xws thiab EL, nws kuj tseem siv tau los ua qhov tseem ceeb rau kev ntsuas cov txheej txheem lithography. Yog hais tias nws yog normalized, uas yog, multiplied los ntawm cov kab dav, lub normalized duab nqes hav (NILS) yuav tau, raws li tau txhais nyob rau hauv formula (7-15), uas yog,
Feem ntau, U (x) yog hais txog cov duab spatial projected los ntawm lub lens rau hauv photoresist, uas ntawm no yog hais txog "cov duab latent" tom qab photochemical cov tshuaj tiv thaiv ntawm photoresist. Rau cov kab ntom ntom nrog qhov sib npaug sib npaug, CD=P / 2, thiab lub sijhawm spatial P yog tsawg dua λ/NA, NILS tuaj yeem sau ua
Piv txwv li, rau 90nm nco txheej txheem, kab dav CD yog sib npaug rau 0.09μm, yog tias qhov sib piv yog 50% thiab lub sijhawm spatial yog 0.18μm, ces NILS yog 1.57.
Qhov tob ntawm Focus (Leveling Method)
Qhov tob ntawm Focus (DOF) yog hais txog qhov siab tshaj plaws ntawm focal length variation nyob rau hauv qhov kev tso cai ntawm kab dav variation. Raws li pom nyob rau hauv daim duab 7.13, lub photoresist yuav tsis tsuas hloov nyob rau hauv kab dav, tab sis kuj nyob rau hauv morphology raws li lub focal ntev hloov. Feem ntau hais lus, rau photoresists nrog siab pob tshab, xws li 193nm photoresists thiab 248nm photoresists nrog siab daws teeb meem, thaum lub dav hlau focal ntawm lub tshuab photolithography yog qhov tsis zoo, lub dav hlau focal ze rau saum lub photoresist; thaum lub nam piv yog ntau dua 2.5-3, vim txoj kab loj nyob rau hauv qab ntawm lub photoresist, txawm "undercut" yuav tshwm sim, uas tej zaum yuav ua rau mechanical instability thiab tipping. Thaum lub dav hlau focal nyob ntawm tus nqi zoo, vim yog txoj kab dav dav nyob rau sab saum toj ntawm photoresist zawj, cov square fab nyob rau sab saum toj yuav dhau los ua puag ncig (sab saum toj rounding). Qhov "sab saum toj rounding" yuav raug xa mus rau cov khoom siv morphology tom qab etching, yog li ob qho tib si "undercut" thiab "rounding" yuav tsum tau zam.
Yog hais tias kab dav cov ntaub ntawv nyob rau hauv daim duab 7.13 yog plotted, ib tug nkhaus ntawm kab dav piv rau focal ntev ntawm txawv exposure energies yuav tau txais, raws li qhia nyob rau hauv daim duab 7.17.
Qhov sib txawv ntawm kab dav nrog focal ntev nyob rau hauv raug lub zog ntawm 16, 18, 20, 22, 24 kuj hu ua Poisson plot.
Yog tias qhov kev hloov pauv tau tso cai ntawm kab dav yog txwv rau ± 9nm, qhov siab tshaj plaws qhov ntev focal ntev variation ntawm qhov pom lub zog raug pom los ntawm daim duab 7.17. Tsis tas li ntawd xwb, vim hais tias hauv kev ua haujlwm tiag tiag, ob qho tib si lub zog thiab focal ntev hloov pauv tib lub sijhawm, xws li drift ntawm lub tshuab lithography, nws yog ib qho tsim nyog kom tau txais qhov siab tshaj plaws kev hloov pauv ntawm focal ntev nyob rau hauv cov xwm txheej ntawm lub zog drift. Raws li pom nyob rau hauv daim duab 7.17, ib tug tej yam tso cai variation ntau yam ntawm kab dav EL, xws li ± 5% raws li tus qauv (EL=10%), yuav siv tau los xam qhov siab tshaj plaws focal ntev variation ntau yam, uas yog nyob nruab nrab ntawm 19 thiab 21 mJ / cm2. Cov ntaub ntawv EL tuaj yeem npaj tawm tsam qhov ntev focal ntev, raws li qhia hauv daim duab 7.18. Nws tuaj yeem pom tias hauv 90nm txheej txheem, nyob rau hauv qhov sib txawv ntawm 10% EL, qhov siab tshaj plaws tsom qhov tob yog li 0.30μm.
Puas yog txaus? Feem ntau hais lus, qhov tob ntawm kev ua kom pom tseeb yog cuam tshuam nrog lub tshuab photolithography, xws li kev tswj xyuas qhov tseeb, nrog rau kev ruaj ntseg ntawm lub tshuab focal dav hlau, qhov chaw curvature ntawm lub lens, astigmatism, leveling raug, thiab flatness ntawm silicon wafer platform. . Tau kawg, nws kuj tseem cuam tshuam rau qhov flatness ntawm silicon wafer nws tus kheej thiab qib ntawm flatness txo los ntawm cov txheej txheem chemical-mechanical flattening. Rau qhov sib txawv ntawm cov thev naus laus zis, qhov tob ntawm qhov xav tau ua kom pom tseeb tau teev nyob rau hauv Table 7.1.
Txij li thaum qhov tob ntawm kev tsom xam yog qhov tseem ceeb heev, theem, qhov tseem ceeb ntawm lub tshuab lithography, yog qhov tseem ceeb heev. Txoj kev siv qib siab tshaj plaws hauv kev lag luam niaj hnub no yog los txiav txim siab txoj haujlwm ntsug z ntawm silicon wafer thiab qaij kaum Rxthiab Ry
nyob rau hauv kab rov tav kev taw qhia los ntawm kev ntsuas txoj hauj lwm ntawm lub teeb pom kev tshwm sim los ntawm oblique teeb meem teeb nyob rau saum npoo ntawm silicon wafer, raws li qhia nyob rau hauv daim duab 7.19.
Lub kaw lus tiag tiag yog qhov nyuaj dua, suav nrog yuav ua li cas cais cov neeg sab nraud z, Rx, thiab Ry. Txij li thaum peb qhov kev ywj pheej no yuav tsum tau ntsuas ib txhij, ib lub teeb ntawm lub teeb tsis txaus (tseem muaj ob txoj kev ywj pheej rau kev hloov mus rau sab), thiab tsawg kawg yog ob kab teeb ntawm lub teeb yuav tsum tau.
Ntxiv mus, yog tias nws yuav tsum tau kuaj z, Rx, thiab Ryntawm cov ntsiab lus sib txawv ntawm thaj chaw raug los yog qhov sib tsoo, tus naj npawb ntawm lub teeb yuav tsum tau nce ntxiv. Feem ntau, rau thaj chaw raug, tuaj yeem muaj txog li 8 txog 10 qhov ntsuas ntsuas. Txawm li cas los xij, txoj kev ntsuas qib no muaj nws cov kev txwv. Vim tias oblique teeb pom kev zoo yog siv, xws li 15 degree mus rau 20 degree grazing kaum sab xis ntawm qhov xwm txheej (los yog 70 degree txog 75 degree teeb meem lub kaum sab xis txheeb ze rau ntsug kev taw qhia ntawm silicon wafer nto), rau qhov chaw xws li photoresist thiab silicon dioxide nrog lub teeb dawb refractive index ntawm li 1.5, tsuas yog li ntawm 18% mus rau 25% ntawm lub teeb yog reflected rov qab, raws li qhia nyob rau hauv daim duab 7.20, thiab lwm yam txog 75% mus rau 82% ntawm lub teeb nkag mus rau hauv lub detector yuav nkag mus rau hauv lub pob tshab nruab nrab nto. . Ib feem ntawm lub teeb kis no yuav txuas ntxiv mus kom txog thaum nws ntsib qhov nruab nrab opaque lossis qhov nruab nrab ntawm qhov cuam tshuam, xws li silicon, polysilicon, hlau, lossis qhov nruab nrab siab refractive index nruab nrab, xws li silicon nitride, thiab tom qab ntawd rov qab los.
Yog li ntawd, qhov "nto" tiag tiag kuaj tau los ntawm cov txheej txheem leveling yuav nyob rau qhov chaw hauv qab ntawm qhov saum npoo ntawm photoresist. Txij li thaum lub nraub qaum-kawg-ntawm-tus-kab (BEOL) feem ntau muaj cov txheej txheem oxide tuab, xws li ntau yam silicon dioxides, yuav muaj qee qhov focal ntev sib txawv ntawm lub hauv ntej-kawg-ntawm-tus-kab (FEOL) thiab lub nraub qaum-kawg, feem ntau ntawm 0.05 thiab 0.20 μm, nyob ntawm qhov tuab ntawm qhov nruab nrab pob tshab thiab qhov cuam tshuam ntawm qhov nruab nrab opaque. Yog li ntawd, nyob rau hauv lub nraub qaum-kawg, tus qauv tsim ntawm cov nti yuav tsum tau ua kom zoo li qub; txwv tsis pub, vim qhov tsis sib xws ntawm cov qauv ntom ntom, nws yuav ua rau muaj qhov tsis sib xws, uas yuav qhia qhov tsis raug qaij them nyiaj thiab ua rau defocus.
Feem ntau muaj ob hom rau qib ntawm photolithography tshuab:
(1) Planar hom: ntsuas qhov siab ntawm ob peb lub ntsiab lus ntawm qhov chaw raug lossis tag nrho cov silicon wafer, thiab tom qab ntawd nrhiav lub dav hlau raws li qhov tsawg tshaj plaws squares txoj kev;
(2) Dynamic hom (tshwj xeeb rau kev luam theej duab photolithography tshuab): dynamically ntsuas qhov siab ntawm ob peb lub ntsiab lus hauv cheeb tsam scanned slit, thiab tom qab ntawd tsis tu ncua them nyiaj raws li kev ntsuas ntsuas. Tau kawg, nws yog ib qho tseem ceeb kom paub tias qhov kev tawm tswv yim ntawm kev sib tw yog ua tiav los ntawm kev txav lub silicon wafer platform nce thiab nqis thiab tilting raws cov kev taw qhia tsis-scanning. Nws cov nyiaj them tuaj yeem tsuas yog macroscopic, feem ntau ntawm qib millimeter. Ntxiv mus, nyob rau hauv cov kev taw qhia tsis-scanning (X kev taw qhia), nws tsuas tuaj yeem ua tiav raws li qhov kev txiav txim thawj zaug qaij, thiab txhua qhov kev tsis sib xws (xws li lub lens curvature thiab silicon wafer warping) tsis tuaj yeem them, raws li qhia hauv daim duab 7.21. .
Nyob rau hauv hom dynamic, qee lub tshuab lithography tuaj yeem nres qhov ntsuas ntsuas rau qhov chaw tsis tiav (hmoov) lossis nti thaj chaw ntawm ntug ntawm silicon wafer (qhov chaw raug nrog qhov siab tshaj plaws.
tuaj yeem muaj ntau qhov chaw nti, hu ua tuag), thiab siv qhov cuam tshuam los yog nti cheeb tsam cov ntaub ntawv nyob ib puag ncig nws rau epitaxy kom tsis txhob ntsuas qhov yuam kev tshwm sim los ntawm qhov siab sib txawv thiab tsis tiav zaj duab xis txheej ntawm ntug ntawm silicon wafer. Hauv ASML lithography tshuab, qhov haujlwm no hu ua "Circuit Dependent Focus Edge Clearance" (CDFEC).
Muaj ob peb yam tseem ceeb uas cuam tshuam rau qhov tob ntawm kev tsom xam: tus lej aperture ntawm lub kaw lus, lub teeb pom kev zoo, kab dav ntawm cov qauv, qhov ntom ntawm cov qauv, ci kub ntawm photoresist, thiab lwm yam. Raws li pom hauv daim duab 7.22, raws li yoj optics. , ntawm qhov zoo tshaj plaws focal ntev, tag nrho cov teeb rays converged mus rau lub tsom xam muaj tib theem;
Txawm li cas los xij, ntawm txoj hauj lwm defocused, lub teeb rays dhau los ntawm ntug ntawm lub lens thiab lub teeb rays dhau los ntawm qhov chaw ntawm lub lens mus txawv teb chaws txoj kev, thiab lawv qhov txawv yog (FF'- OF'). Thaum tus lej aperture nce, qhov sib txawv ntawm qhov pom qhov sib txawv kuj nce ntxiv, thiab qhov tseeb ntawm lub teeb pom kev ntawm qhov defocus yuav me dua, los yog qhov tob ntawm kev tsom xam yuav me dua. Nyob rau hauv lub teeb pom kev sib luag, qhov tob ntawm kev ua kom pom tseeb (Rayleigh) feem ntau muab los ntawm cov qauv hauv qab no, uas yog,
Qhov twg θ yog qhov siab tshaj plaws qhib lub kaum sab xis ntawm lub lens, sib xws rau cov lej aperture NA. Thaum NA tseem me me, nws tuaj yeem sau kwv yees li
Nws tuaj yeem pom tau tias thaum NA loj dua, qhov tob ntawm kev ua kom pom tseeb me dua, thiab qhov tob ntawm kev ua kom pom tseeb yog inversely proportional rau lub square ntawm tus lej aperture.
Tsis tsuas yog tus lej aperture cuam tshuam rau qhov tob ntawm kev ua kom pom tseeb, tab sis kuj yog lub teeb pom kev zoo. Piv txwv li, rau cov duab ntom ntom, thiab lub sij hawm spatial tsawg dua λ / NA, off-axis illumination yuav ua rau kom qhov tob ntawm kev tsom. Qhov no yuav rov hais dua hauv Tshooj 7.1 ntawm Tshooj 7 nrog kev teeb pom kev tsis zoo. Tsis tas li ntawd, txoj kab dav ntawm cov duab kos kuj tseem cuam tshuam rau qhov tob ntawm kev ua kom pom tseeb. Piv txwv li, qhov tob ntawm kev ua kom pom tseeb ntawm cov duab me me feem ntau me dua li cov duab ntxhib. Qhov no yog vim hais tias lub diffraction yoj lub kaum sab xis ntawm cov duab me me yog qhov loj, thiab lub kaum sab xis ntawm lawv cov convergence hauv focal dav hlau kuj loj. Raws li tau hais los saum no, qhov tob ntawm kev tsom xam yuav me dua. Tsis tas li ntawd, qhov ci kub ntawm photoresist tseem yuav cuam tshuam qhov tob ntawm kev tsom mus rau qee yam. Qhov siab dua tom qab qhov ci ci (PEB) yuav ua rau qhov nruab nrab ntawm qhov sib piv ntawm cov duab spatial nyob rau hauv txoj kab ntsug (Z) nyob rau hauv lub thickness ntawm photoresist, uas ua rau kom qhov tob ntawm kev tsom xam. Txawm li cas los xij, qhov no yog tus nqi ntawm kev txo qhov siab tshaj plaws duab sib piv.
Mask yuam kev Factor
Mask Error Factor (MEF) lossis Mask Error Enhancement Factor (MEEF) yog txhais tias yog ib feem ntawm cov kab dav nthuav tawm ntawm silicon wafer nrog rau lub ntsej muag kab dav. Lub npog ntsej muag yuam kev feem ntau yog tshwm sim los ntawm qhov sib txawv ntawm qhov kho qhov muag thiab yuav loj dua vim qhov txwv tsis pub muaj kev ntseeg siab ntawm photoresist rau cov duab spatial. Cov xwm txheej cuam tshuam rau lub npog ntsej muag yuam kev suav nrog cov teeb pom kev zoo, cov khoom siv photoresist, lithography tshuab lens aberrations, tom qab ci (PEB) qhov kub thiab txias, thiab lwm yam hauv kaum xyoo dhau los, muaj ntau cov ntaub ntawv qhia txog kev tshawb fawb ntawm daim npog ntsej muag yuam kev hauv cov ntaub ntawv. Los ntawm cov kev tshawb fawb no, nws tuaj yeem pom tias lub sijhawm me me lossis qhov sib piv ntawm cov duab me me, qhov loj dua lub npog ntsej muag yuam kev. Rau cov qauv uas loj tshaj qhov raug wavelength, los yog nyob rau hauv lub thiaj li hu ua linear range, lub npog qhov ncauj qhov yuam kev qhov feem ntau yog ze heev rau 1. Rau cov qauv uas nyob ze los yog me dua lub wavelength, lub npog qhov ncauj qhov yuam kev qhov yuav ua rau kom loj. . Txawm li cas los xij, tshwj tsis yog cov xwm txheej tshwj xeeb hauv qab no, lub npog ntsej muag yuam kev feem ntau tsis tsawg dua 1:
(1) Kab lithography siv qhov hloov pauv hloov lub npog ntsej muag tuaj yeem tsim lub npog ntsej muag yuam kev tsawg dua 1. Qhov no yog vim qhov tsawg kawg nkaus lub teeb siv nyob rau hauv cov duab spatial thaj chaw faib khoom feem ntau yog tshwm sim los ntawm 180 degree theem kev hloov pauv tsim los ntawm theem nyob ib sab. . Hloov qhov dav ntawm txoj kab hlau ntawm lub npog ntsej muag ntawm lub sijhawm hloov pauv tsis tshua muaj txiaj ntsig ntawm txoj kab dav.
(2) Lub npog ntsej muag yuam kev yuav muaj tsawg dua 1 nyob ze ntawm cov qauv me me hauv kev kho qhov muag sib thooj. Qhov no yog vim qhov kev hloov me me rau tus qauv tseem ceeb tsis tuaj yeem txheeb xyuas tau zoo los ntawm cov duab kos duab nrog kev daws teeb meem tsawg los ntawm kev sib txawv.
Feem ntau, rau cov qauv txuas ntxiv xws li kab lossis grooves thiab qhov sib cuag, lub npog ntsej muag yuam kev yog sib npaug los yog ntau dua 1. Vim tias qhov tseem ceeb ntawm lub npog ntsej muag yuam kev yog nyob rau hauv nws txoj kev sib raug zoo nrog cov kab dav thiab daim npog qhov ncauj, nws ua heev. tseem ceeb kom txwv nws mus rau ib qho me me. Piv txwv li, rau lub rooj vag txheej nrog cov kab dav dav dav dav dav, qhov kev ua yuam kev ntawm lub npog ntsej muag feem ntau yuav tsum tau tswj qis dua 1.5 (rau 90nm thiab cov txheej txheem dav dua).
Txog thaum tsis ntev los no, tau txais cov ntaub ntawv ntawm daim npog ntsej muag yuam kev yuav tsum muaj cov lej simulation lossis kev sim ntsuas. Rau cov lej simulation, ua kom tiav ib qib ntawm qhov tseeb yuav tsum tau ua raws li kev paub hauv kev teeb tsa simulation tsis. Yog tias cov ntaub ntawv hais txog kev faib cov npog ntsej muag yuam kev hauv tag nrho qhov chaw lithography parameter yuav tsum tau siv, cov txheej txheem no yuav siv sijhawm ntev. Qhov tseeb, rau kev thaij duab ntawm cov kab ntom ntom lossis grooves, lub npog ntsej muag yuam kev muaj qhov ntsuas kwv yees kwv yees hauv kev xav. Nyob rau hauv cov xwm txheej tshwj xeeb uas lub sij hawm spatial p yog tsawg dua λ / NA thiab qhov dav ntawm txoj kab yog sib npaug ntawm qhov dav ntawm qhov zawj, nyob rau hauv cov xwm txheej annular illumination, cov lus piav qhia tau yooj yim thiab sau rau hauv daim ntawv hauv qab no, uas yog ,
+, - muaj feem xyuam rau grooves thiab kab, ntsig txog. Ntawm lawv, σ yog ib feem ntawm qhov tsis sib xws (0＜σ ＜1), yog qhov hloov pauv hloov pauv hloov pauv hauv lub ntsej muag hloov pauv hloov pauv (piv txwv li, rau 6% daim npog ntsej muag, yog 0.25 ), n yog photoresist refractive index (feem ntau ntawm 1.7 thiab 1.8), thiab a yog qhov sib npaug photoacid diffusion ntev nyob rau hauv tus qauv pib (nyob ntawm qhov sib txawv tshuab nodes, feem ntau ntawm 5 mus rau 10 nm rau 32 rau 45 nm nodes rau 7 0 nm rau 0.18 rau 0.25 μm nodes).
Rau qhov hloov pauv hloov pauv daim npog ntsej muag (Alt-PSM), MEF muaj cov lus qhia yooj yim dua, uas yog
Ntawm lawv, lub sij hawm spatial p<3λ / (2NA), CD refers to the line width on the silicon wafer, and δ refers to the line width on the mask. If we plot equation (7-21), we can get the result in Figure 7.23. It can be seen that MEF increases rapidly as the spatial period decreases, and increases as the photoacid diffusion length increases.
Yog tias tag nrho cov kev txwv tshwj tsis yog lub photoacid diffusion ntev nyob rau hauv cov mis (7-21) paub, qhov ntev diffusion ntawm photoacid tuaj yeem tau los ntawm kev ua kom haum cov ntaub ntawv sim. Cov txiaj ntsig tau pom tias tom qab 40 vib nas this tom qab ci, lub photoacid diffusion ntev ntawm ib hom 193nm photoresist yog 27nm; Tom qab 60 vib nas this tom qab ci, qhov ntev diffusion ua 33nm. Thiab vim qhov tseeb ntawm cov ntaub ntawv, qhov ntsuas qhov tseeb ntawm qhov ntev diffusion ntawm photoacid yog ± 2nm. Qhov no yog qhov kev txiav txim siab ntau dua li qhov tseeb ntawm cov kev ntsuas yav dhau los, raws li pom hauv daim duab 7.24. Lub npog ntsej muag yuam kev kuj tseem tuaj yeem siv los xam cov kev xav tau ntawm lub npog ntsej muag kab dav rau kab dav uniformity, nrog rau kev teeb tsa ntawm cov kev cai sib nrug ntawm cov duab ob sab hauv kev kho qhov sib thooj ntawm qhov sib thooj. Rau ob-dimensional duab nrog luv luv kab xaus, raws li qhia nyob rau hauv daim duab 7.25, los ntawm kev suav ntawm ib tug yooj yim point kis muaj nuj nqi thiab ib tug tej yam degree ntawm approximation ntawm lub photoacid diffusion, ib tug ze li ntawm analytical mis rau cov kab kawg optical sib thooj nyhuv yuav ua tau. tau, uas yog,
Qhov twg PSF yog lub ntsiab lus nthuav dav, cov ntawv sau "D" sawv cev rau qhov sib txawv ntawm cov photoacid, ib qho sawv cev ntawm photoacid diffusion ntev, n=1, 2 sib raug rau cov teeb pom kev sib txuas thiab tsis sib xws, thiab
Kab dav uniformity
Kab dav uniformity nyob rau hauv cov txheej txheem semiconductor feem ntau muab faib ua: thaj chaw nti, thaj chaw txhaj tshuaj, thaj chaw wafer, thaj chaw ntau, thiab thaj chaw ntau-rau-ntau. Cov yam tseem ceeb uas cuam tshuam rau kab dav sib xws thiab kev tsom xam dav dav ntawm qhov cuam tshuam muaj nyob rau hauv Table 7.2. Los ntawm Table 7.2, peb tuaj yeem pom tias:
1) Feem ntau, cov teeb meem tshwm sim los ntawm cov tshuab lithography thiab cov txheej txheem qhov rais muaj kev cuam tshuam dav.
(2) Cov teeb meem tshwm sim los ntawm kev tsim lub ntsej muag yuam kev lossis qhov cuam tshuam ntawm qhov muag pom feem ntau txwv rau thaj chaw raug.
(3) Cov teeb meem tshwm sim los ntawm txheej los yog substrate feem ntau txwv rau silicon wafer.
CMOS li feem ntau xav tau kab dav sib xws li ± 10% ntawm kab dav. Rau cov rooj vag, kev tswj qhov tseeb yog ± 7%. Qhov no yog vim hais tias nyob rau hauv cov txheej txheem hauv qab ntawm 0.18μm ntawm node, feem ntau yog ib txoj kab dav "trim" etching txheej txheem tom qab lithography thiab ua ntej etching, uas ntxiv txo cov lithography kab dav mus rau cov cuab yeej kab dav, los yog ze rau cov cuab yeej kab dav, uas. feem ntau yog 70% ntawm lithography kab dav. Txij li thaum tswj cov cuab yeej kab dav yog ± 10%, lithography kab dav dhau los ua ± 7%.
Muaj ntau txoj hauv kev los txhim kho qhov sib xws ntawm lithography kab dav, xws li kev them nyiaj rau qhov raug hluav taws xob faib tawm hauv lub teeb pom kev ntawm lub tshuab lithography raws li kev ntsuas qhov sib txawv ntawm qhov tshwm sim hauv cheeb tsam raug. Qhov kev them nyiaj no tuaj yeem ua tiav ntawm ob theem. Nws tuaj yeem raug them nyiaj rau hauv lub tshuab tsis tu ncua, uas yog siv tau rau txhua qhov teeb pom kev zoo, lossis nws tuaj yeem raug them nyiaj hauv qhov raug cuam tshuam (raws li qee qhov kev cuam tshuam). Nyob rau hauv txoj kev no, nws tuaj yeem raug tsom rau qee qib nrog cov kev cai nruj nruj. Nws kuj tseem tuaj yeem txhim kho los ntawm kev txheeb xyuas lub hauv paus ua rau qhov tsis sib xws lithography kab dav. Piv txwv li, ib qho teeb meem tshwm sim yog qhov cuam tshuam ntawm qhov siab sib txawv los ntawm cov txheej txheem txheej txheem ntawm silicon wafer substrate ntawm lub rooj vag kab dav uniformity. Piv txwv li, hauv zos kab dav uniformity (Local CD Variation, LCDV) ntawm lub rooj vag txheej sib tham hauv [6] yuav deteriorate vim qhov siab hloov pauv ntawm substrate. Qhov kev hloov pauv no tau qhia hauv daim duab 7.28.
Cov kab dav hloov pauv los ntawm qhov siab sib txawv yog pom hauv daim duab 7.29 thiab daim duab 7.30. Nws tuaj yeem pom tau tias thaum qhov siab sib txawv maj mam txo qis, cov kab dav maj mam txo qis rau tus nqi ruaj khov.
1. Kev txhim kho ntawm kab dav uniformity hauv cheeb tsam nti lossis hauv cheeb tsam duab
Txij li muaj ntau yam cuam tshuam rau qhov no, tsuas yog qee txoj hauv kev tseem ceeb tau tham.
(1) Txhim kho lub qhov rais txheej txheem thiab optimize lub qhov rais txheej txheem.
Txog cov duab ntom, oxis illinumination tuaj yeem siv tau los txhim kho ob qho tib si pom tseeb, thiab theem-ua haujlwm qhov ncauj qhov ntswg tuaj yeem siv los txhim kho ib qho txawv;
Rau cov duab cais, sub-diffraction scattering strips (SRAF) tuaj yeem siv los txhim kho qhov tob ntawm kev ua kom pom tseeb ntawm cov duab cais;
Rau cov duab ib nrab cais, uas yog, lub sij hawm spatial tsawg dua ob zaug ntawm qhov tsawg kawg nkaus spatial lub sij hawm thiab me ntsis loj dua qhov tsawg kawg nkaus spatial lub sij hawm, cov txheej txheem qhov rais ntawm no yuav mus txog rau ib tug yuav luag nyuaj lub xeev, los yog hu ua "forbidden suab", raws li qhia. hauv daim duab 7.31
Raws li tuaj yeem pom los ntawm daim duab 7.31, txheeb ze rau lub sijhawm tsawg kawg nkaus ntawm 310nm, kab dav poob los ntawm 130nm mus txog 90nm ze rau lub sijhawm 500nm. Qhov no (tsis muaj nyob ntawm no) kuj muaj qhov poob qis hauv qhov sib piv thiab qhov tob ntawm kev ua kom pom tseeb. Kev txwv tsis pub lub sij hawm spatial yog tshwm sim los ntawm qhov yuav tsum tau ua kom muaj qhov dav tsawg kawg nkaus nyob rau hauv lithography ntawm cov logic circuits, uas ua rau tsis muaj qhov sib txawv loj hauv cov duab tsis sib npaug hauv cov sijhawm sib txawv lossis cov qauv nyob ib sab. Nws yog feem ntau tshwm sim los ntawm Off-axis teeb pom kev zoo imposes cov kev txwv ntawm semi-dense graphics. Feem ntau, off-axis teeb pom kev zoo tsuas yog muaj kev pabcuam zoo rau lub sijhawm tsawg kawg nkaus, tab sis muaj qee yam tsis zoo rau cov duab "semi-dense" ntawm qhov tsawg kawg nkaus lub sijhawm thiab 2 zaug ntawm qhov tsawg kawg nkaus lub sijhawm. Txhawm rau txhim kho cov txheej txheem qhov rai thaum lub sijhawm hu ua txwv tsis pub, lub kaum sab xis ntawm lub qhov hluav taws xob tawm ntawm qhov hluav taws xob yuav tsum raug txo kom tsim nyog kom ua tiav cov kab dav dav sib npaug.
(2) Txhim kho qhov raug thiab kev ntseeg tau ntawm kev kho qhov sib thooj ntawm qhov sib thooj.
Cov txheej txheem yooj yim ntawm kev kho qhov sib thooj ntawm qhov sib thooj yog: thaum tsim cov qauv, thawj zaug tsim qee cov duab calibration ntawm daim npog qhov ncauj qhov ntswg raws li qhia hauv daim duab 7.32. Tom qab ntawd, tus qauv loj ntawm photoresist ntawm silicon wafer yog tau los ntawm kev nthuav tawm cov silicon wafer, thiab tom qab ntawd tus qauv yog calibrated (qhov cuam tshuam tsis zoo ntawm tus qauv yog txiav txim siab), thiab tus nqi kho yog xam tib lub sijhawm. Tom qab ntawd, raws li qhov sib xws ntawm cov duab tiag tiag thiab cov duab calibration, nws raug kho raws li tus qauv.
Qhov tseeb ntawm kev kho qhov sib thooj ntawm qhov sib thooj yog nyob ntawm cov hauv qab no: silicon wafer linewidth cov ntaub ntawv ntsuas qhov tseeb, qauv haum qhov tseeb, thiab kev tsim nyog thiab kev ntseeg tau ntawm tus qauv Circuit Court qauv kho algorithm, xws li sampling (fragmentation), sampling point density Select, yog cov kauj ruam loj, thiab lwm yam. Rau cov qauv photoresist, muaj feem ntau yooj yim pib qauv nrog rau Gaussian diffusion (threshold qauv nrog gaussian diffusion) thiab qhov sib txawv ntawm cov qauv tiv thaiv. Tus qub xav tias photoresist yog lub teeb hloov. Thaum lub teeb siv mus txog ib qho chaw pib, qhov kev sib cais ntawm cov photoresist hauv tus tsim tawm hloov tam sim ntawd. Qhov tom kawg yog vim qhov sib txawv ntawm qhov qub los ntawm kev sim cov ntaub ntawv. Lub tom kawg ntseeg hais tias photoresist yog ib tug complex system, thiab nws cov tshuaj tiv thaiv pib muaj feem xyuam rau lub siab tshaj plaws lub teeb siv thiab gradient ntawm lub siab tshaj plaws lub teeb siv (uas yuav ua rau directional diffusion ntawm photosensitive tus neeg sawv cev), thiab tej zaum yuav yog ib tug tsis-linear kev sib raug zoo. Thiab tom kawg kuj tuaj yeem piav qhia qee qhov etching kab dav sib txawv ntawm ntom rau cov qauv sib cais. Tau kawg, tus qauv zoo li no tsis tuaj yeem qhia lub cev duab kom meej meej. Feem ntau hais lus, lub cev duab ntawm tus qauv pib ntxiv rau Gaussian diffusion yog qhov tseeb heev, thiab tib neeg siv nws ntau dua, tshwj xeeb tshaj yog nyob rau hauv cov txheej txheem kev txhim kho thiab kev ua haujlwm zoo. Nyob rau hauv cov nqe lus ntawm kho qhov muag qhov sib thooj nyhuv, vim hais tias nws yog tsim nyog los tsim ib tug qauv raug rau ib tug ob peb nanometers nyob rau hauv ib tug luv luv lub sij hawm, ntxiv ib co ntxiv tsis uas nws lub cev lub ntsiab lus yuav tsis tau piav qhia meej yog tsis muaj kev zam thiab kuj yog ib qho kev ntsuas ib ntus.
Tau kawg, raws li cov txheej txheem photolithography txuas ntxiv txhim kho, photolithography qhov sib thooj ntawm cov nyhuv kho tus qauv yuav txuas ntxiv hloov zuj zus thiab nqus cov tsis muaj lub ntsiab lus ntawm lub cev. Txhawm rau ua kom qhov tseeb ntawm tus qauv, koj tuaj yeem nthuav cov neeg sawv cev ntawm kev ntsuas cov duab los ntawm kev nce cov ntsiab lus ntsuas (xws li 3 mus rau 5 zaug), uas yog, txhim kho qhov ntsuas (gauge) cov duab, raws li pom hauv daim duab. 7.32 ib. Tib lub voj voog tsim cov duab kos nyob rau hauv Kev sib raug zoo thiab zoo sib xws hauv cov duab geometric. Thaum lub sij hawm tus qauv haum tus txheej txheem, sim siv lub cev tsis thiab pub rov qab qhov haum tsis raug rau tus lithography engineer rau kev tsom xam kom tshem tawm qhov yuam kev. Kev kho qhov sib thooj ntawm qhov sib thooj ntawm qhov muag yuav tau tham txog qhov tob hauv lwm tshooj.
(3) Optimize lub thickness ntawm anti-reflection txheej.
Vim qhov sib txawv ntawm qhov ntsuas qhov ntsuas qhov ntsuas (n thiab k qhov tseem ceeb) ntawm photoresist thiab substrate, ib feem ntawm lub teeb pom kev zoo yuav rov qab los ntawm qhov sib cuam tshuam ntawm photoresist thiab substrate, ua rau cuam tshuam nrog qhov teeb meem duab teeb. Thaum qhov kev cuam tshuam loj heev, nws tseem tuaj yeem tsim cov nyhuv nthwv dej, raws li pom hauv daim duab 7.33 (c). Daim duab 7.33 (c) qhia txog ntu ntu ntawm i-line 365nm lossis 248nm photoresist. Vim hais tias qhov kev ncua deb ntawm lub ncov nyob rau hauv lub sawv nthwv dej yog ib nrab ntawm lub wavelength, thiab lub refractive index n ntawm lub photoresist feem ntau yog nyob ib ncig ntawm 1.6 mus rau 1.7, raws li tus naj npawb ntawm peaks (~ 10), nws tuaj yeem suav tau. tias lub thickness ntawm photoresist yog li ntawm 0.7 mus rau 1.2μm. Lub thickness ntawm 193nm photoresist feem ntau yog tsawg dua 300nm. Txhawm rau tshem tawm cov teeb pom kev hauv qab ntawm photoresist, feem ntau siv cov txheej hauv qab los tiv thaiv kev cuam tshuam (BARC), raws li pom hauv daim duab 7.34 (a). Hauv daim duab 7.34 (a), ib qho kev sib txuas ntxiv tom qab ntxiv cov txheej txheem tiv thaiv hauv qab. Cov theem ntawm lub teeb pom kev nyob nruab nrab ntawm cov txheej tiv thaiv kev cuam tshuam thiab cov substrate tuaj yeem hloov kho los ntawm kev kho cov tuab ntawm cov txheej txheem tiv thaiv kev cuam tshuam los cuam tshuam lub teeb pom kev ntawm cov photoresist thiab cov txheej thaiv kev cuam tshuam, yog li tshem tawm cov teeb pom kev ntawm lub teeb. hauv qab ntawm photoresist. Rau cov txheej txheem tiv thaiv kev cuam tshuam, yog tias nruj tiv thaiv kev cuam tshuam yuav tsum tau ua tiav ntawm qhov tuab ntawm li 1/4 wavelength, lub refractive Performance index n ntawm anti-reflection txheej yuav tsum tau precisely kho kom nws nyob nruab nrab ntawm n.Substratethiab nPhotoresistntawm lub substrate, uas yog,
(4) Optimize lub thickness thiab viav vias nkhaus ntawm photoresist
Txawm tias nyob rau hauv qab anti-reflection txheej, tseem yuav muaj ib tug npaum li cas ntawm residual lub teeb reflected los ntawm lub hauv qab ntawm photoresist. Qhov no ntawm lub teeb yuav cuam tshuam nrog lub teeb pom kev los ntawm sab saum toj ntawm lub photoresist, raws li pom hauv daim duab 7.35 (a) thiab daim duab 7.35 (b). Raws li lub thickness ntawm photoresist hloov, theem ntawm "reflected light 0" thiab "reflected light 1" hloov ib ntus, yog li ua rau cuam tshuam. Kev hloov pauv ntawm lub zog los ntawm kev cuam tshuam yuav ua rau lub zog nkag mus rau photoresist hloov pauv raws li qhov tuab ntawm photoresist hloov, yog li cov kab dav yuav hloov pauv raws li qhov tuab ntawm cov photoresist hloov, raws li qhia hauv daim duab 7.35 (b). Feem ntau muaj ntau txoj hauv kev los daws qhov teeb meem ntawm kab dav hloov pauv nrog photoresist thickness:
Optimize lub thickness thiab refractive index ntawm anti-reflection txheej (xaiv ib tug haum anti-reflection txheej)
Xaiv ob txheej los tiv thaiv kev cuam tshuam (feem ntau yog ib qho ntawm lawv yog ib qho inorganic anti-reflection txheej, xws li silicon oxynitride SiON)
Ntxiv cov txheej tiv thaiv sab saum toj (Sab saum toj ARC, TARC) kom tshem tawm cov teeb pom kev nyob rau sab saum toj ntawm lub photoresist
Txawm li cas los xij, ntxiv cov txheej txheem tiv thaiv kev cuam tshuam yuav ua rau cov txheej txheem nyuaj thiab kim. Thaum lub qhov rais txheej txheem tseem siv tau, lub thickness nrog cov kab tsawg tshaj plaws yog feem ntau xaiv. Qhov no yog vim hais tias thaum lub thickness ntawm photoresist hloov, txoj kab dav yuav loj dua, tsis me, yog li ntawd lub qhov rais txheej txheem yuav sharply me me.
2. Lwm txoj hauv kev los txhim kho kab dav uniformity
Txhim kho qhov sib xws ntawm cov teeb pom kev zoo, qhov tsis sib xws, focal ntev thiab qib tswj, platform synchronization raug thiab kub tswj qhov tseeb ntawm lub tshuab lithography; txhim kho lub uniformity ntawm daim npog qhov ncauj kab dav; txhim kho lub substrate thiab txo qhov cuam tshuam ntawm substrate ntawm lithography (nrog rau kev ua kom pom tseeb ntawm qhov tob thiab txhim kho cov txheej txheem tiv thaiv kev cuam tshuam). Ntawm lawv, Tshooj 4.2 tau hais tias nce qhov sib xws ntawm tus qauv tsim yog qhov tsim nyog rau kev txhim kho qhov tseeb ntawm qib thiab ua kom qhov tob ntawm kev tsom mus. Lub ntug roughness ntawm tus qauv feem ntau tshwm sim los ntawm cov hauv qab no yam:
(1) Lub hauv paus roughness ntawm photoresist: Nws muaj feem xyuam rau qhov hnyav molecular ntawm photoresist, qhov loj me me ntawm qhov hnyav molecular thiab qhov concentration ntawm photoacid generator (PAG).
(2) Qhov sib piv ntawm photoresist txoj kev loj hlob dissolution tus nqi nrog rau qhov nce ntawm lub teeb siv: lub steeper qhov kev hloov ntawm lub dissolution tus nqi nrog lub teeb siv nyob ze ntawm lub chaw pib zog, qhov me me qhov roughness tshwm sim los ntawm ib feem ntawm txoj kev loj hlob.
(3) Photoresist rhiab heev: Qhov tsawg dua qhov photoresist cia siab rau tom qab raug ci (PEB), qhov roughness ntawm txoj kab dav yuav ntau dua. Kev ci tom qab kis tau tuaj yeem tshem tawm qee qhov tsis sib xws.
(4) Qhov sib piv lossis lub zog ntawm cov duab photolithographic: qhov sib txawv ntau dua, qhov nqaim ntawm qhov chaw ntawm ntug ntawm tus qauv tsim, thiab qhov qis dua qhov roughness. Nws yog feem ntau qhia los ntawm kev sib raug zoo ntawm kab dav roughness thiab daim duab cav nqes hav (ILS).
Rau chemically amplified photoresists, txhua photoacid molecule generated los ntawm photochemical cov tshuaj tiv thaiv yuav undergo ib deprotection catalytic cov tshuaj tiv thaiv nyob rau hauv ib tug ntau yam ntawm diffusion ntev nrog rau tiam point raws li qhov chaw ntawm lub voj voog thiab lub vojvoog raws li lub vojvoog. Feem ntau hais lus, rau 193nm photoresists, qhov ntev diffusion yog nyob rau hauv thaj tsam ntawm 5 txog 30nm. Qhov ntev ntawm qhov diffusion ntev, qhov zoo dua cov qauv roughness thaum cov duab sib piv tseem tsis hloov. Txawm li cas los xij, nyob ze ntawm qhov kev daws teeb meem, xws li nyob ze ntawm 45nm ib nrab suab, qhov nce ntawm qhov ntev diffusion yuav ua rau txo qis hauv qhov sib piv ntawm cov duab, thiab qhov txo qis hauv qhov sib piv ntawm cov duab yuav ua rau muaj kev nce hauv cov qauv roughness.
Tus nqi dissolution ntawm photoresist feem ntau hloov los ntawm ib qho qis heev mus rau qib siab heev nyob rau hauv ib kauj ruam-zoo li lub teeb siv hloov. Yog tias qhov kev hloov pauv zoo li no yog steeper, qhov chaw hu ua "ib feem ntawm txoj kev loj hlob", uas yog, qhov chaw hloov pauv hauv nruab nrab ntawm cov kauj ruam hloov, yuav raug txo, yog li txo qhov roughness ntawm tus qauv. Tau kawg, kev sib cais ntau dhau yuav cuam tshuam rau qhov tob ntawm kev tsom xam. Rau qee qhov 248nm thiab 365nm photoresists, qhov sib txawv me me me tuaj yeem txuas ntxiv qhov tob ntawm kev tsom mus rau qee yam, raws li qhia hauv daim duab 7.36.
Qhov siab dua ntawm cov photoresist, qhov luv ntawm photoacid diffusion ntev (qhov siab dua qhov kev ncaj ncees ntawm cov duab saum toj kawg nkaus thiab qhov kev daws teeb meem siab dua), vim tias cov photoresists feem ntau tsis tshua muaj nyob ntawm qhov kev sib kis tom qab ci, uas tuaj yeem ua rau qee yam qib. ntawm cov qauv roughness. Txawm li cas los xij, yog tias qhov concentration ntawm photoacid generator yog nce nyob rau tib lub sijhawm, qhov xwm txheej no tuaj yeem txhim kho. Kev txhim kho qhov sib piv ntawm cov duab photoresist tuaj yeem txo cov qauv roughness, raws li qhia hauv daim duab 7.37.
Lub roundness ntawm kev sib cuag qhov thiab vias yog zoo ib yam li roughness ntawm tus qauv. Nws kuj tseem muaj feem xyuam rau qhov sib txawv ntawm photoacid, qhov concentration ntawm photoacid, qhov sib txawv ntawm cov duab, thiab qhov sib txawv ntawm kev txhim kho photoresist. Peb yuav tsis tham txog lawv ib leeg ntawm no.
Photoresist morphology
Qhov txawv txav hauv photoresist morphology muaj xws li sidewall qaij lub kaum sab xis, sawv yoj, thickness poob, hauv qab footing, hauv qab incision, T-top, sab saum toj rounding, kab dav roughness, nam piv / qauv dumping, hauv qab residue, thiab lwm yam. Peb yuav tham txog lawv ib tug los ntawm ib tug. , raws li qhia hauv daim duab 7.38.
Lub kaum sab xis: Qhov no feem ntau yog vim tias lub teeb nkag mus rau hauv qab ntawm photoresist tsis muaj zog dua li lub teeb nyob rau saum toj (vim qhov nqus ntawm lub teeb los ntawm photoresist). Qhov kev daws teeb meem yog feem ntau txo qhov nqus ntawm lub teeb los ntawm photoresist thaum nce qhov rhiab heev ntawm photoresist rau lub teeb. Qhov no tuaj yeem ua tiav los ntawm kev nce ntxiv ntawm cov khoom siv photosensitive thiab ua kom cov nyhuv catalytic ntawm photoacids hauv cov tshuaj tiv thaiv deprotection (diffusion-catalysis cov tshuaj tiv thaiv). Lub kaum sab xis ntawm phab ntsa yuav muaj qee yam cuam tshuam rau etching, thiab thaum mob hnyav, lub kaum sab xis yuav raug xa mus rau cov khoom siv etched substrate.
Standing yoj: Cov nyhuv yoj sawv ntsug tuaj yeem daws tau zoo los ntawm kev ntxiv cov txheej txheem tiv thaiv kev cuam tshuam thiab tsim kom muaj qhov sib txawv ntawm cov photosensitizer (xws li los ntawm kev nce qhov kub los yog lub sijhawm tom qab ci kom nce qhov diffusion ntawm photoacids).
Thickness poob: Txij li thaum lub sab saum toj ntawm photoresist tau txais lub teeb muaj zog tshaj plaws thiab sab saum toj yog raug rau cov neeg tsim tawm tshaj plaws, lub thickness ntawm photoresist yuav ploj mus rau ib qho twg tom qab kev txhim kho tiav.
Ko Taw: Cov hauv qab taw yog feem ntau tshwm sim los ntawm cov kua qaub-piv qhov tsis sib xws ntawm photoresist thiab cov substrate (xws li hauv qab los tiv thaiv txheej). Yog hais tias lub substrate yog alkaline los yog hydrophilic, lub photoacid yuav neutralized los yog absorbed rau hauv lub substrate, ua rau lub deprotection cov tshuaj tiv thaiv nyob rau hauv qab ntawm lub photoresist yuav tsum tau muaj kev cuam tshuam. Kev daws rau qhov teeb meem no feem ntau yog ua kom cov acidity ntawm lub substrate, nce lub pre-exposure ci kub ntawm photoresist thiab anti-reflective txheej, thiaj li mus txwv lub diffusion ntawm photoacid nyob rau hauv lub photoresist thiab nyob rau hauv lub substrate. Txawm li cas los xij, kev txwv qhov diffusion kuj tseem cuam tshuam rau lwm yam khoom, xws li roughness ntawm tus qauv, qhov tob ntawm kev tsom xam, thiab lwm yam.
Undercut: Contrary to the bottom footing, undercutting is because the high acidity at the bottom of photoresist, thiab deprotection cov tshuaj tiv thaiv nyob rau hauv qab yog siab tshaj nyob rau hauv lwm qhov chaw. Qhov kev daws teeb meem yog qhov txawv ntawm qhov saum toj no.
T-topping: T-topping yog tshwm sim los ntawm alkaline (puag) cov khoom hauv huab cua hauv lub Hoobkas, xws li ammonia, ammonia (ammonia), thiab amine organic compounds (amine), uas nkag mus rau sab saum toj ntawm photoresist thiab neutralize. ib feem ntawm photoacid, ua rau ib qho loj hauv zos kab dav nyob rau sab saum toj, thiab nyob rau hauv cov mob hnyav, nws yuav ua rau kab adhesion. Txoj kev daws teeb meem yog tswj hwm cov ntsiab lus alkali ntawm huab cua hauv thaj chaw photolithography, feem ntau tsawg dua 20 ppb (ib feem ntawm ib billion), thiab sim ua kom lub sij hawm luv luv los ntawm kev kis mus rau tom qab raug ncua.
Sab saum toj rounding: Feem ntau, lub teeb siv irradiated nyob rau sab saum toj ntawm lub photoresist kuj loj. Thaum txoj kev loj hlob zoo sib xws ntawm cov photoresist tsis siab heev, qhov no ntawm lub teeb pom kev zoo yuav ua rau kom muaj kev sib cais ntau ntxiv, yog li ua rau sab saum toj mus rau puag ncig.
Linewidth roughness: Linewidth roughness tau tham ua ntej.
Aspect ratio/pattern collapse: nam ratio yog tham vim hais tias thaum lub sij hawm txoj kev loj hlob txheej txheem, tus tsim tawm, deionized dej, thiab lwm yam yuav tsim lateral nro tsim los ntawm nto nro nyob rau hauv lub photoresist qauv tom qab kev loj hlob, raws li qhia nyob rau hauv daim duab 7.39. Rau cov qauv ntom ntom, txij li qhov nro ntawm ob sab yog roughly tib yam, qhov teeb meem tsis loj heev. Txawm li cas los xij, rau cov qauv ntawm ntug ntawm cov qauv ntom, yog tias qhov sib piv loj, nws yuav raug unilateral nro. Ua ke nrog kev cuam tshuam ntawm kev sib hloov ceev ceev thaum lub sij hawm txoj kev loj hlob, tus qauv yuav vau. Cov kev sim qhia tau hais tias qhov siab-rau-dav piv saum toj 3: 1 feem ntau txaus ntshai.
Scumming: Yog vim li cas rau scumming feem ntau yog cov hauv qab photoresist tsis nqus lub teeb txaus, ua rau muaj kev loj hlob ib nrab. Txhawm rau txhim kho qhov kev daws teeb meem ntawm photoresist, qhov diffusion ntev ntawm photoacid yuav tsum tau txo qis, thiab qhov kev loj hlob ntawm qhov sib txawv tshwm sim los ntawm qhov diffusion ntawm photoacid yog txo. Ua li no, qhov roughness ntawm qhov chaw nce. Lub hauv qab scumming feem ntau yuav raug txo los ntawm optimizing lub teeb pom kev zoo, daim npog qhov ncauj kab dav kev tsis ncaj ncees, thiab ci kub thiab lub sij hawm los txhim kho cov duab spatial zoo sib xws thiab ua rau kom raug rau ib cheeb tsam.
Alignment thiab overlay raug
Alignment yog hais txog kev sau npe ntawm cov khaubncaws sab nraud povtseg. Feem ntau hais lus, qhov tseeb overlay ntawm cov khaubncaws sab nraud povtseg yuav tsum nyob ib ncig ntawm 25% ~ 30% ntawm qhov tseem ceeb (qhov loj me) ntawm silicon wafer. Ntawm no peb yuav tham txog cov hauv qab no: txheej txheem overlay, overlay parameters thiab sib npaug, overlay marks, khoom siv thiab technical teeb meem ntsig txog overlay, thiab cov txheej txheem uas cuam tshuam rau overlay raug.
Cov txheej txheem overlay tau muab faib ua thawj txheej (lossis pem hauv ntej txheej) kev sib dhos kos cim kev tsim khoom, kev sib dhos, kev sib dhos, kev sib haum xeeb, photolithography tshuab nyiaj them, raug, overlay raug ntsuas tom qab raug, thiab suav cov kev sib tw tom ntej ntawm kev sib raug zoo, raws li qhia hauv daim duab 7.40 . Lub hom phiaj ntawm kev sib tshooj yog ua kom qhov sib tshooj ntawm qhov sib koom ua ke ntawm silicon wafer nrog silicon wafer platform (uas yog, kev tswj hwm ntawm lub tshuab photolithography). Rau qhov linear, muaj plaub yam tsis muaj: txhais lus (Tx, Ty), nyob ib ncig ntawm lub axis ntsug (Z), rotation (R), thiab magnification (M). Cov kev sib raug zoo hauv qab no tuaj yeem tsim los ntawm kev sib koom ua ke ntawm silicon wafer (Xw, Yw) thiab lub tshuab photolithography tswj qhov system (XM, YM):
XM=TX+M[XW cos(R)-YW sin (R)]
