PROC'EEDINCiS (-)f THE l~IRST l_N I ER'.\ATl()'\AL
`SYJ\.1POSllJJ\1 0"1 lJL·l-R.I\ J.,\RCJE S(~ALl:'. IN"l-EGRA l Jl)'.\
`SCIE'.\.('E ANll l-FCHNQJ_()GY
`
`ULSI SC'IENCE AND 'IEC:HNOLOGY; 198~
`
`Edited by'
`
`S. Broydo
`ZyMOS Corporation
`Sunnyvale, California
`
`CM. Osburn
`MCNC
`Research Triangle Park, North Carolina
`
`Assistant Editors
`
`J.M. Androws
`LJ.A. A!lloniadis
`W lv1_ Bullis
`GK_ G811.,,
`l1 ll Fr,.se•
`S G<J<><1,v1i1-Jol1anoson
`G J Hu
`Iida
`Y
`R.~'· Jaccod!nA
`HJ Lev1n~t""'
`E' __ Middlesworth
`
`y_ N'shi
`L.C Parrillo
`J.R. Pt"'~·-er
`A Reisman
`G.C. Sch"·~rt~
`A S•nha
`
`J Van dnr Spiegel
`'JCJ3hchenkuv
`/\ M
`\11.'"ng
`D N K
`
`ELECTRON/CS AND DIELECTRIC.<:; AND /NSU/ A TION DIVISIONS
`
`Proceed1ngs VolLJmf'l 87-11
`
`Tl IE: ELECTROCHEMICAL SOCIETY, ING., 10 SoLJth Main St, Penn•rigton, NJ 08534-2891
`
`SAMSUNG-1005.001
`
`

`
`Copyright 198/
`by
`The Electrochemical Society, Incorporated
`
`Papers contained herein may not be
`reprinted and may not be digested by pub(cid:173)
`lications other than those of The Electrochemical
`Society in excess of 116 of the material presented.
`
`Libr<Jry of Congress Catalog Number: 87-82381
`r'rir1tod 1n t~ie United States of America
`
`SAMSUNG-1005.002
`
`

`
`SELF AL.LGtl"ElJ BITLINE CONTl\.C'I' FOR 4 MHT'I' DRAM
`
`J{.JJ.J{li.,sters, H.M.1'.uehll>o£f, C. Endors, E.G.Mohr
`and W.Mueller
`
`'l'echnology,Techn.Center
`Corporate Research Rnc.
`tor Mi croel.,ctroni<:s, Sie:nens AG, O<: to-liahn-l>.i11g 6,
`D-8000 Vunich !l.l,
`c.;errna11y
`
`dRAM cell ;siz" i><
`4 MbiL
`r"duct.i.011 i!l
`A ?.5 %
`,..,:£ aligned bit::i11., conta::t, which
`1'Chieved by a
`is ~ully J:J',;erllipping qate and field axide(FC•BIC).
`No additional nasks .:i.re
`requil.·ed. 'l'he gate
`.i.s
`encapsulst.,d by oxide usir1g an oxide spscsr
`technique. A
`thin oxide/nitride/oxide dielectric
`llllows
`a
`contact. hole etch, which doeg not.
`signi::ica:"ltly affect
`the oxide insulation of the
`gate and
`the field <ixir .... The ni.t:cide serves as
`an etch stop tor top oxide etch, the final etch
`ctep rerr,oves on:y a thin diolcctric.
`A 0.9 ,urn contact bct"'ccn polyc:ide (TaSi) bitline
`<50Q), 0.2 ,um diatanr.8 to
`"n<l n~ diffuo;i.on (R, 0
`gate is
`re,.lized without deterioratic~. of tran(cid:173)
`sistor propert:'..es, Ne
`yiE>ld
`reductior. due
`to
`gatc/bitline-
`shorts
`occurs. No
`infl-_,_<>ncc of
`i>i tride on dev:'..ce propert.ies
`:'..s
`•Jbser·,·ed
`for
`nitridD thickness ~sor.m.
`
`l. Tntr,1ductiun:
`
`4M DR!'I.~ concepts are based on J dim"nl'li<>n"l cell e;truct.ures
`such as
`trench capacitor cell (1)
`and
`stacked capacitor
`cell. Thei.r in-::cgration :'..nto --:;he pi·ocess flow and t.J-.e i·eal.c(cid:173)
`zation of
`sub micron design
`rulcs sot new dema!lds
`for
`process development. Howe••eL' Lo
`obLai11 a c;J1ii1 ><iz<-> ,,f le""
`t.hi'!:-.
`1 00
`furt.h<>r
`innovations
`are
`necessary.
`mm~
`Tn trti,; paper we
`report a
`t.r .. nc:h c:ap"c'tor cell with se.L:
`aligned, fully ov.,,rlappi.ng t>itlin"' contact (FCBIC). Tht> cell
`design a.:.icws
`the contact holG to overlap gate <>nd field
`oxidB; the
`co'1.t-.act are"
`;"
`independant of
`lithographO.c
`alignment tolerances. The registration tolerance for bi tline
`c:ontacts is
`l'>lirnin"t"d (s"" fig. 1)
`'l'hus the cell area ca11
`be shritnk by
`25 % ccrnpared
`to
`a
`conventional contact
`technique:.
`~'Ice proposed process is different. from p;:;ovious concepts fo:c
`self aligned contacts (2-5)
`in which
`cl1e Lherrnai oxide of
`gat.e polysilicon
`.i.s used as <.ir\ irtt..,r-!ev .. l
`il'.sulator between
`
`6~0
`
`SAMSUNG-1005.003
`
`

`
`gates anC.
`intcrco1li1ections. The process has
`to rnatc:h
`tl1e
`r<'!ql,iremen"Os of
`rel.'._able submicron LDD transistoo-s, whiCI>
`clre deteriorated by a
`slrong Lcoxidation ot gat"' poly-
`silicon.
`Ir. contrast w.i.LlL a
`recent 5Clf
`al.Lgncd COllt'1CL Lec:l1nology
`(G) whicJ1 use,; 11itride
`J,D[) "l"''"'"'rs and gate Crl<;d.po;ulation,
`un oxicfP
`spacer technique i~ ut>ed J,ec;,11s<'! of LLlD tra!lsistoL"
`reli'1bi l i t.y.
`fl. new Lecl>r1iq1".e tor cc.chi ng the dielec:t;r;-i<.:: unde;r;-neath thC>
`oit.-ino is
`u~<0d to
`e'1Sll>"•' a
`gorocl insulation of bitline to
`polysi 1 icon '}ates
`("'ordline) drtd
`,;ul>~t.rqte fo:c-
`the over(cid:173)
`la.pp.crly c;ont"o:t.~.
`'l'he FOBIC
`co11tacL t-'rt,l::<>ss
`is integrated
`into tJ-,c 4 ~lbiL t-'ro<;.,ss tlow '~ithout. i'l.-',<liLiOr1cll r1ao;ks.
`
`2. Proceso; flow
`
`The~ Mhit. clRAM
`.i.o; fabric:ated >-;ith i'l 0.9 µ_in
`lwir1 wcoll pro(cid:173)
`<.::ess. Atler
`t.rencl1 capac;it<:r Ltnd LDD transistor formatio:i a
`low ,-esisL.cviLy E>oly·c:icle (poly Si/'l'aS.i. 2
`l"y"r 1-~ llSed for
`hit·lln<0s and
`loci!!
`t-'eriphPr"l
`intcrconilec:Ls.
`'I':1e
`sec:ond
`i11terconnect ],-,•Jrol
`C<)JLo;io;t" of T:'../TiN/AlSi. n1eLall.czcilion.
`1''0L ~·c>n'Oacts connecting the polycide biLlirie ton< ct<ffnsion
`(souroc_,/drain of
`Lr<l11~f..,r gates) the POBIC piocaso; (Iig. ?)
`is employe,d.
`
`)
`
`2 .1 Oxide <>n""P"'''lation of the gate
`Aftcr paLLeL·z:ir1g "double
`layer of poly Si/oxide {0.1 11m
`TF:OS) Ltn oxide speccr
`is ~Orm<'>d hy Ol<.Ld<! deposition (TEOS)
`and RIR
`"tcl'.ing (CH~_,/o~). The sp?.c<'>r
`. ..,idth
`(0.2 µm)
`is
`deLern\i11ed by
`1.on transistor op::.io\i~ation. Th" roly g"'tc is
`in5ulatcd by ilL le<.1,;~ 0. J 5 ,urn oxide. A ve:t:1..Lcal <0tcl1 protile
`ot poly Si/nxicle> w!-:..Lch
`coan be achi.,,ved hy sequenL.:.al uxide
`otch (CHF3/Q,)
`unG poly Si etch (Cl~/He) is esser.t.Lal.
`The Silne
`techniqu0> foe oxide encapsu.:.ciLiun of -:he gate has
`illse bee11
`ilppl.ceU -:o
`" r:o~yc:(de gate with arc ox:'..d0> spacer
`covering thG
`side"Nalls of
`d tripl" layer ot poly Si/TaSi~/
`oxide.
`
`2.2.l contact. hole eLch
`'::'he dielectric undor the biLlirle consists of a .:riple layer
`of thin oxide/nitride/oxide. ~or 1.he Lop oxide
`a
`reflow
`t"c.:l111ique
`(E'1'! .• -diffusion and backetch of the doped oxide) is
`employed, wi-:h a final thickn0>ss of 0.2/um-
`The tripl"
`l"ye:r <lielectrie allows a
`conlaeL
`liole etch,
`wl1icll does not significantly afrect the field oxide and t)LU
`oxide insulation
`i:if thc gate (see fig. 2). Aft"r pat.terning
`th., c:ont:nct. hole mask
`the top oxide is etched u,;ing
`th"
`nitride as
`an etch stop. ~he oxide etch can Le perfurmed
`a', by
`d;r;-y etching, b) by wet. <'>t.ching, or a combination of
`boL:o.
`
`SAMSUNG-1005.004
`
`

`
`"-) ~·oL· dry etching
`" C!Jr3 p.:.asma •:ith a selectivity <>f 4: l
`"''itl: L'espect
`tc the nJ_tride is
`'!Hed (fig. 1u). Ourinq
`n·J<>retch tl1e 11itride etch rate reduces rlue to "n Rnh,,nced
`J.,·,eloprrter1L cf
`a C rich polymer film nn t.hR nit-.ri<l<•. Tlte
`o·Jeretch t.·m" h"~ Lo
`be sufficient
`(> 70
`";) to remov"
`oxido c;paoers on th<> nitride. 'l'hereforG a nito:idc t:~ic:k­
`'.less :>
`70 nrr, i~ rPquired "-" u11 &~ch stop. Aftc::: removing
`the polymer
`film by
`l>r p_asm",
`tl1"' conLncL hole etch
`c:ur,Li<lues wi.l:b etching the n:.tride (Sf'o .,-,,,.~m,,, fie;.
`:J!J;
`~clocti--vo.:.y -::o
`tnu u11der_y_ing oxide> (~ 50 run)
`'l'o
`,::pJQjd
`.:ir11 11iLLi<le
`sic.:icers alvng
`the gates an ov,.r<>t-.1:h uf 70 %
`1-Ll
`Il'--''--''--'"""ry.
`'l'lJ·-' L-02nain.:.i1g
`thir. <1xida
`.ts removed b}" "(cid:173)
`cl1ort dL"Y et.ch ~top (:::HF~/0~1
`a n'trid" luy"L'
`b) lf Llle LOf-' oxide is ""t otchc~d (NH.,F/HF)
`of
`lOruu i~ ~llfficient for
`the <>t".roh Htt)p. The
`thir>
`11iLLi::le a11d Lhe Lh.i.n
`ox::.de (-
`nm)
`llnde,-n<>a~_:-_ dL8
`~"
`<>t-_,.h,o,:i hy
`t-.hH ~cl:ne
`l:H~' 3 /0, d.::y ot:;h step
`(::ig.
`4;o;.
`Tl1t1 ut<o> uf " L'1Ll1aL' Lfi:..n ilitridc a~ an etch stop i_;; alsci
`ciossihle .tt C"Om'.-.ining
`a
`eLc'.1 ol
`tlle
`top oxide
`dLy
`n "'"t
`(without lorig cveretch) i\nd
`<>t_cl1 to I-eHlC'Je oxide
`s:oac:ers on
`the :".itrid<>.
`'T'h" u"" <>f
`'-' weL "Loll step occms
`e>isoi proforablc because o~ a
`taper1 ~g ot t-.he ccintcicL !tole
`edg". ~£ dTiy e,or,\'entional
`con7,,ct_s are' p11t_ternad ~'( the
`scc1ne n\ask C\lld techniquc,
`the contacL hole size
`;,., r1cot
`nff"c-t_ed liy
`d
`.,,.,L
`eLch sLep
`for thco
`top oxide as the
`underlying nitrtd.,/ol<ide i" '--'~L·lic_.d a11isolro1>J.cally .
`LtLe 1-'-"'-'cess
`(see fi;r.
`3c,4b,4c) an oxide
`. O.tter r-:ol"lpl.,~_ing
`insul,.tion ct thR gnt-.<> >
`I ?:O
`r>TIL
`io, uDL"i11ed, Llle [ield oxide
`thi.nn1ng in
`7.':to cocir1tact
`l1ole is '1L most 50 nn1. The contact
`aren ot t.he "<ORIC r-:ont_a<:t-_ is de[iried !Jy <J'-'-L" u11d fiald ·C>xidc
`edges. The distance ot
`the cn-t_,,r.t_
`t<>
`t-_h,.
`ga7_,,
`i~ 011.:.y
`0. 2
`l-\1'1-
`?.?:.?: l'.or1LtlcL hole etch-alternative process
`'l'l1e essei>tial
`fco~tllr:C of
`-::he contact ho~e e-:ch prop<>><totl 111
`2.2.l is
`-;:l:<i u~e <Jf drl
`tlch stop layei- for the t.op C>x:ide.
`Only a
`thin dielectr:'..c
`i~ lRft
`ftir th., find] cLc;l1 3tep by
`which the oxicte insul,,t.i<or_ of ttLe yute dild ~lte field oxide
`Oil.fl be
`::hinnod. Bocause
`i'.1 th<!
`c:a~R nt n pnr<> <:ry eLc:h of
`lup L~X.Lde
`the r.,-,qu'rc-rl nit.ride thickness
`is
`7J nm,
`an
`alternative process
`"Jlnv.•irg t_h.,
`''"" nf "t.hir.ner nitI-:.de
`even (or
`a pt.trc dry etch process has been
`l.:c~·estiga-t.ed.
`(::'O nm) ""c!
`Ins"O<.>o>d uf 11it.t'ide a dccbl" l"Y"'' of ni_t-.r:i_d<'>
`r"ly-c~i (30 nn)
`:Cs
`u~cd. E'oly Si is a '~ery efficient: etch
`CH~'~/o~ plasma (select:Cvi.ty >
`si:op for et:ching ''xid"
`i11 u
`2Ll,1). Ilowev.,r,
`d <.or.L.i.nous
`layer of poly Si can call""
`shorts or probleIPs •:h"'"
`"tcl1i11g
`co11LacL hol"s
`fron1
`the
`socond metalli.zaticn
`level to source/drain ~reas. ~her.,fure
`- att.er top oxid., etch, poly Si eLch (•»e~ or Cl~/He plasn1"),
`and resist
`strii;-,pir.g -
`thF! poly ~i i" cl:dnged int<> 005.i.de
`:Jy
`wet oxidation
`(900-C,20 min)
`The poly Si c-an be oxidized
`although buried unc,er the
`top oxi<l<>
`b<>c~"""' t.he t<'l' oxide
`
`642
`
`SAMSUNG-1005.005
`
`

`
`th.,o:-mcil uxide. Duri11g uxidatiur1
`tl1tl11
`;.,,.,. der1s"'
`('l'EOS) is
`the 11cti•;e areas. A
`final etch
`the nitride
`is protecting
`the nitride and 11ndRrlying
`step (CHF 3 /0~ r,lasma) removes
`thin oxidQ, leading to the result ~hown i;i fjg. 5.
`
`2.3 Polycide interconnect level
`"l"u.S.i.7
`L>y
`fcir1ued
`is
`Afler ::<intact-.
`h<il•> "t:;h
`Ll1<-> loitlin"
`(200nm) on top of poly Si (lOOnrn). Poly Si is dope<i hy A~ <>r
`P Tmpli'.ntation. A5 shown by SIMS "nalysi5 Phn,.phnrc11~ ''11t(cid:173)
`diftusion during
`sc:~s.::,'Iuent ann,,aling
`5t'->pS
`(BPSG
`retlnw
`900°C, 40
`rii11) in
`changin<J t-.h,-, vr:::tical dnpin<J pr<1fi le of
`th" l\s dopod sourco/drain areas. "Ihcr.,,foi·o the effec•c on th"'
`ligf1tly doped
`d:r:<ii:· ceqions o~ the t!.'i'-'Osist.ors Oldjaccnt t"
`the acJ f
`"1.J.gncd contsct has
`to
`Joe
`chocked {see 4. 2).
`'l'lle c.or1LdCL
`i·e~isLan:oe po:y Si co r.--diffu~i.on can
`bco
`ii1fJu.,r\c.,,f by "ll.irl native oxide
`cJt Ll1i:;
`i11Lei·f<ice.
`I'o
`bre<i:~ Lili:; uxi.de ion 1nixinq ( 7 I is applied: ['::i.rt. of the P
`:or
`As do~<> is 'mpldnted irtt.u ttte .c11terface b;;tweeri tl1e 1-'uly o;i
`1'nd r--ct;1·t1;,.•on. Pi·J· 6
`"how" t_h.,
`g<"orn .. try d .. p .. nd.,nc" cJf
`cor>~dct rt,t<istar1ce wiLh
`<.t11d w.cLl1cut
`iur1 1"ixir1g
`~C.·L As
`irr,pl1'nt.r.tion ·nt-.o ?'>ly ~;i. For nn ,.ff.,cot.ive bit1ine ccntaoot
`
`w1d-.. 0 • C>f 0.9 ,''"' les= than sn Qare ot:tained.
`
`3. Dcvico characterization
`
`3.1 Isolation of bitlinc to transfer gate and substrate
`,.;g. 7
`shows a worcil1n<> t;o hit-J.in"' leakage current; di,.t.ri(cid:173)
`hi:ti'1n for
`f:RJl1" ""ll nrrny8 wit-I'.
`,,,..d ·,;it.hont FORTC c:<J11tc1·~t ..
`t:o yieid
`reduction due
`to FCEIC contacts ).S observed, anrf
`ic.olation bi·oa6dciwn
`is cau~cd by sace
`:oxide
`failure.
`ro
`~uppross the
`lcaksge current psth across
`the gate oxide
`speci.<>.:
`l:est-st:r:uct.ures
`on
`fie.ld oxi:ie were e·~aluatcd
`(fi·,i. 8)
`!leluw 20 V tl1e le,,kage c·urrent is b.,luw de~ec:LiO•l
`li:niL, b.L<O<Lkdow;' o[ t.tie OAide i"~ul.>L.i.ort uccurs only
`at.
`volt.age,; l>igl1eoL·
`tltclr! 50 '!.
`the
`l'OllTC r.ont_,,,--:t; prr.cPss was
`Anot;hRr con<"<"rn
`1'ho•1t. t.h<>
`influe11ce of iield oxide tr.inning (max. 50nm) irl r'.".e contact
`hoie on C,iodc propertios. Expcrimcnts with diffcl.·ont ovcr(cid:173)
`ctch show no effect en p-r_
`junctions as long as the field
`oxide ·_hin1-,1,,g is less chan BOnm.
`
`] . 2 Tr<.11tsisLor proper Lies
`Current-vo]ta9<> r:h1'rnc:t.Rristic" {fig. 9) of transistor" wit-.h
`and wit-.J-.cr.1t. FORTC con-c1'ct show no d'ffe,--oncc. No cff'-"Ct of P
`doped poiy Si(bitline) on transistor behaviour was observed,
`<ilt.hough lateral diff'-lsion of P into LDD regions was one of
`r'-"Sults L>f transistors
`the concerns. Short time DC stress
`W).t.h <Lnd without l'OBIC cantact also o;.:hibit no difference.
`llecdu~e of I.he hiqher gat<> :itack the shadowi11g effect of the
`LDD Implantation (8,9) cecomes mor'-" pronounced. However, th'-"
`LDD impl<int.
`shadowinq effect
`is effectively ·ceduced by
`
`C4.J
`
`SAMSUNG-1005.006
`
`

`
`in1plunt,,tiC>n jsee
`rctil.tir1·;i Lhe waf.,rs dur.'._r19
`'dB.f<>r
`t'.".e
`;_,, divided into 4 equal do"co;,
`d<ose
`imp_l_ant<>ticir>.
`90 G.egrees after eil.::;h
`
`LDD
`9 ) . T'."lc
`is rotated hy
`
`3. 3 Nitride ett<>c:t on device
`'"hicl> is nc·t removed
`n.'._L:r:idc layer,
`'lite irllL'Oduc-::ion of a
`fl'1w, has been ir.~·,,.stL­
`Ll1e p:::cccss
`Iron1 the wafior dc:r1r1g
`gnt.<>d very carefully. For Bil.ride thickneA" uI ~ lOOrun "n
`cuLLent is obse1·v.,d [or large
`er.:".anced g<>t.ed diode lea)<"q"
`(no overl"f-•pinq contact), As sl1own b;{ 'l'EM
`t-.ran,.,istuL <.trray·s
`(tig_ 10) ci11d C:ef.,ct analy"i~, ge:c8L'iltion of tJ..,~.,cL~ (di,,lo(cid:173)
`appe'1L'S at -::lie eclq" <>I Ll1c
`catinn;;, point d<=Iect c:l11~-::erE)
`i~ b"r1d1ng
`:.ayer
`tJ-.n r.iLLiJG
`~t->ilCGr, where
`gate's ox1d"
`,,.:_Lridc can ""''"" Q1l
`this purticular site t.h"
`upwards
`ltc
`<"nhanc<Od st-.rR<;s. For ni LLide tl1ic:kr . .,.ss ot '.J01u,, cleteri orat:..orl
`J-.igh rever~e
`for
`occur,,;
`cu1;,·cnt
`diocte l<,ak.icre
`o{ C1iltcd
`i: i trid0 dAposi tioi1
`parar1et.<>r~
`en
`dep<>ndJ_r1g
`( 9V)
`'•olLc!ye
`(>';J>hanced JAnkn::re Ct<J::ccnt is obsf>r,•ed ior l0"'"r clepo~it_ton
`leakage
`(750~l:)). To avoid any e~[ect on
`Ler1peraturos
`th"
`t-'ara!ll"-'T.2rs)
`JliL:r·ide dcposit1<>n
`':urre11~ (for all CVD
`fiivor'ng
`30i1m
`LL
`tu
`bc redUC<>d
`l1us -:0
`11.'._Lridc t'.'lickne""
`,,..,-,t_ "'Lcll "tcp (SPR
`i11clu.ding a
`c<>r1tacL ~.o].::, etch p:--,ice"~
`2.2.l) or Lile process out_Jin•><l in 2.2.2.
`~nvesLigiltion of hor "l<ectr0n d"'gradation (fig. l l j ,;hews a
`rlitride
`tor"-
`f,,cLor of five
`"
`:Cifctime hy
`re<1'1c:t.ior1 in
`Le• d"''ic:es witl1ouL Q
`·1ay<>r t'licknc"" of 13~ n:TL co!'lpared
`nLtr1c!<> lo>yer, while tor ~ ~O run nitriC.e nn
`lifet1 m" i~ uLse,;vcd.
`
`Ac:kr1ow 1 c·dgenent_
`Lo B.liasler, W.'!eybeL·q, 11.!len<in(cid:173)
`ThA nuLlior" are grat-"ful
`gcL, Icir their c-cllnburiltion in thic; work, Lo H.Oppolzer for
`SF.M <lituly,,is.
`to H.llnudek, H.Dcnun tor
`'!'.~;,.
`'!'RJ.' artcilysis,
`work was :;u_ppcrtcd b~' th" Federal rJcpartment. of i;:esearch and
`( sigr .. NT ~6~6).
`'l'<>chr1oloqy
`REf" ilf!.ilr!C ES
`IEDM Tec:h. Dig. 19135,
`H.S•.i.nami,
`C'.Murilmoto, T.Ho>Joya, S.~lutsuo,
`1~7fJ, p.185
`Y .Tcu1i.gaki, S. Iw,.mat,;u,
`Soc-. L978, p. 471
`IEDM T.,'--'l>. Dig. 1980, p.136
`)ol.Sakamoto, K.Hamano,
`J.S.d" Ziildivar, NTG-Fac:hbericl1Le Bd. 77 (1981), p.22
`A.Shinohara, "1.1''u.kumoto, G.Fu""• S.tJdanaka,
`':'.Ic;hihara, llthSSOM 'l'okyo,
`M.Sas,,gn, T.OhzuJ1e,
`],;xt.,,nded Ah><t.racLs, p. 29
`D.K.H.t:icc, J.Appl .PJiys. 46 (1975), p.338-'1
`';>. Mizuno, Y. M<>t!lumotc, S . Sawada, S. Shinozaki,
`O.Ozawa, IEDM Techn. Dig. 1985, p. 250
`f!.M.Mi\hlhof[, P.Murkjn, K.H.Ki.isters, M.Orlowski,
`l-l.11lil ler, Lhi" confAr<er1ce
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`El <>ctruchen1.
`
`SAMSUNG-1005.007
`
`

`
`''"
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`I 0 .DO
`
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`
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`1·ig,l' Layout pattern for bitline contact a) without and
`b) with FOBlC (d~"' dKT- r"giStration tolerance>)
`
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`t~:::'~'\\\0-\" Poly:,
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`FJg.2:
`Process for FOBIC
`r.ontact(wet etch of
`top oxlde as de"(cid:173)
`cibed in 2.2.1, b)
`
`~ \
`
`cross section of
`bitline coolact
`
`SAMSUNG-1005.008
`
`

`
`Fiq. J: t'OB!C process, using
`dry etch for tup uxid.,
`
`3a:f.i.rsi: step o.r conLac•(cid:173)
`hole etch: oxide is
`etched nclcctivoly to
`underlying nitride
`
`Jb:after complete contac~
`hole etch precess
`
`Jc:cross section of 4Mhit df!AM with fully overlapping
`bitlinc contact (dry etch cf top oxi~e)
`
`646
`
`SAMSUNG-1005.009
`
`

`
`nitride=
`
`oxide
`
`Flg.4a:
`After completw
`contect hole
`etch p'Y"OC9EO
`(wet. etch of
`t.op oxide)
`
`l'ig.4b,c:
`cross secti ons of 1Mbit dRAM.
`(\~et etch of top uxide)
`
`Fig.5:
`Proce:;s using a t i'tjn poly Si (20 run) on top of n i tride
`( 30 nm) as etch Atop for etching ~he top oxide {sec 2.2.2)
`Poly Sl is changed into oxide hy wet oxidation (op)
`a} aftwr cor.tact b.ole etch.
`b) after complete pro:::ess
`
`a
`
`0.51Jm
`
`64J
`
`SAMSUNG-1005.010
`
`

`
`;·ig.6:
`c.;.,01n.,try dependanc"
`of contact resistance
`n ·--;>ol yin~ -dit ::us io:i .
`C,Qwt;L CUL'•Je 5h'1W"
`r"dll<-'l-iun due to ion
`1nixing
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`Leakage current
`across wordline
`to bitline iso(cid:173)
`lation (FOBIC
`technology) tor
`test structllre
`on field oxide
`
`SAMSUNG-1005.011
`
`l''ig.7'
`wordline to bitli.!le leakage cu.-renl ('J-10\') distribution
`fur DRAf'. ~all arrays 'O'ith (a) und without (b) "DllIC car.tact.
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`cliaraC't:F>ri s tics
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`•oiLh FOBIC contdCL
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`[A)
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`_ I 10'
`B
`
`F~g.10;
`DeiccLs at spacer edge (nitride
`thic'<ness 130 nm)
`(TEM rcsult)
`
`Fig.11; Short time DC otress results •or wafF>rS with l"JO run
`nitride, 50 nm n!::r~de, withouc nilrtdc
`
`10°/o
`
`61
`I
`
`~130nm
`1o/ot_~,----.~----.,e.~-~~~
`10
`100
`1000.
`t [sec)
`
`SAMSUNG-1005.012