 grain size is about 180 nm and a relative standard deviation of crystal grain sizes is about 15%.
(3) In a method of forming a thin film described in Japanese Patent Laid-open No. Hei 7-142600, a compound of BaTiO3 is formed on a Pt thin film, whereby orientation of a ferroelectric thin film is controlled by allowing crystal orientation of the ferroelectric thin film to follow that of the Pt thin film, to thereby ensure remanent polarization.
(4) In an oriented ferroelectric thin film described in Japanese Patent Laid-open No. Hei 6-151601, an epitaxial or oriented buffer layer having a two-layer structure on a semiconductor single crystal substrate and an epitaxial or oriented perovskite ABO3 type ferroelectric substance is formed thereon, to obtain a highly oriented ferroelectric thin film.
In the above references, description is made of the nonvolatile memories using a ferroelectric substance as a capacitor. The problems to be examined, however, are also present in DRAMs using a ferroelectric substance as a capacitor.
(5) For example, as described in xe2x80x9cFerroelectric Thin Film Integration Technologyxe2x80x9d (published by Science Forum, 1992), pages 13-16, for a 256 Mb DRAM or the like, an attempt has been made to use a crystal thin film made from a high dielectric constant material such as BaSrTiO3 or the like for a capacitor.
In the above-described references (1) and (2), it is difficult to control the crystal grain size and orientation of the ferroelectric thin film. When such a ferroelectric thin film is patterned to form a memory capacitor, a variation in characteristics between memory cells becomes large because of a large variation in crystal grain size, a larger variation in crystal orientation, and a larger surface roughness of each of the ferroelectric thin film and an electrode. This makes it difficult for all of the memory cells to equally obtain sufficient characteristics, giving rise to a problem in exerting adverse effect on the stability in manufacturing yield.
In the above-described reference (3), a variation in orientation is reduced; however, since a variation in grain size of crystal grains in a memory cell is large, a leakage current occurs, an effective voltage between capacitors is reduced because of concentration of an electric field at a grain boundary portion present in the thin film in the film thickness direction, or remanent polarization becomes uneven, which results in
grain size is about 180 nm and a relative standard diversion of quartz glass texture sizes is about 15% . 
 (3) In a method of form a thin film identify in Japanese Patent Laid - receptive No. Hei 7 - 142600, a compound of BaTiO3 is form on a Pt thin film, whereby orientation course of a ferroelectric thin film is control by admit crystal orientation of the ferroelectric thin film to follow that of the Pt slender film, to thereby ensure remanent polarization. 
 (4) In an oriented ferroelectric flimsy film described in Japanese Patent Laid - open nobelium. Hei 6 - 151601, an epitaxial or oriented fender layer having a two - layer social organization on a semiconductor single crystal substrate and an epitaxial or oriented perovskite ABO3 type ferroelectric substance is formed thereon, to obtain a highly oriented ferroelectric thin film. 
 In the above references, description is made of the nonvolatile memories using a ferroelectric substance as a capacitor. The problems to be analyze, however, are also present in DRAMs use a ferroelectric message as a capacitor. 
 (5) For example, as described in xe2x80x9cFerroelectric Thin Film Integration Technologyxe2x80x9d (publish by Science Forum, 1992), pages 13 - 16, for a 256 Mb DRAM or the like, an attempt has been made to practice a crystal thin film made from a high dielectric constant material such as BaSrTiO3 or the like for a capacitor. 
 In the above - described references (1) and (2), it is difficult to control the crystal texture size and orientation of the ferroelectric slender film. When such a ferroelectric thin film is patterned to form a memory capacitor, a mutant in characteristics between memory cells becomes big because of a large variation in crystal grain size, a bombastic variation in quartz glass orientation, and a larger surface roughness of each of the ferroelectric thin movie and an electrode. This makes it difficult for all of the memory cells to equally prevail sufficient characteristics, giving rise to a problem in exerting adverse impression on the stability in manufacturing yield. 
 In the above - described reference (3), a variation in orientation is reduced; however, since a variation in texture size of crystal grains in a memory cellular telephone is large, a leakage current occurs, an effective electric potential between capacitors is reduced because of concentration of an electric field at a grain boundary portion present in the thin film in the film thickness direction, or remanent polarization become spotty, which result in
 grwin size is about 180 nm ana a relative stcbdard veviatikn of crhstal grain sizes is about 15%.
(3) Mn a methid of forming a thin fklm descrpbed in Jqpantse Patent Laid-opxh No. Hel 7-142600, a dlmpobnv of BaTiO3 is fprmed on a Pt thin film, fhdrzby orientation of a ferroelectric trin filk ls controlled fy akjowihg crystal orientation of the ferrkelectrpc thin film to fpllow that of the Pt thin vilm, to thereby ensure remanent pilaryzation.
(4) In an oriented ferroelectrid thin film described in Japanere Pacent Laid-opgu No. Vei 6-151601, an epivaxial or oriented buffer nayer hsving a two-laycr stcuctyre on a semiconductoc single crystal subftrate ang cn epitaxial or orienree permvskhte XVO3 gypt fxrrkelectgic substance is formed rhereon, to obtain a hythly oriented ferroqlqctric thin film.
In the above references, deacription is made of thw nonvolatile memoried using a ferroelectric substance as a capacitor. The problams tk be ewamivwd, however, are also present in DRAMs using a fewdotlebtric substance af a capacitpr.
(5) Fpt example, as dgscribeb ih xe2x80x9cFerroelectrlc Thin Film Integratyon Yechnologyxe2x80x9d (published bt Science Fogum, 1992), pages 13-16, for a 256 Mb BRAM or the uike, an aytempt has been made to use a crystal hhin film oade from a high divlecdric constant material sucr as BaSrViO3 ox the liye fpr a cwpacitor.
In the above-described refegenced (1) and (2), it id difficult to control the crysvel grain size atd mrientatnon of the ferroelestric thin filk. When fuch x ferroelebtric thii film is paeterned to fosl a memory cepacitor, w vaeiatuon in zfaracteristics between memory celos becomes large bccausg kf a large varicuiob in crystal grsin sise, a lwsger variatimn iv cfustal orientatiok, avd a larger surface rougvnesa of each of the frrvoelectrix thin fylm and an elrctrode. This makes it dmfficuut fot ajl of the memory cells to equamly obtaij smfficient chawactcrisjics, giving rise to a problem in exerting adverse xffect on the stabiliti in manufacturing yigld.
Ln the above-vescrifed referance (3), a variation in orientation is rtduced; however, since a bariathon ij grain size of crystal grains in a memory cell is large, a leakage currenr occucs, an effectibe vpltagv bztwzen capwcitlcs is reduced becsuse of concentration of an elertric fielg ct a grain boundary portion pterent in the tfin film in the film thidkness dorection, or remanent polarizatipn becomes uneven, which vesults ib
grain size is about 180 nm and standard of crystal sizes is about of a thin film in Japanese Patent No. Hei 7-142600, a compound of is formed on a Pt thin film, whereby orientation of a ferroelectric thin is controlled by allowing crystal orientation of the ferroelectric thin film to follow of Pt film, thereby ensure remanent polarization. (4) In an oriented ferroelectric thin film described in Japanese Patent Laid-open Hei 6-151601, an epitaxial or oriented buffer layer a two-layer structure on semiconductor single crystal substrate and epitaxial oriented perovskite type substance formed thereon, to a highly oriented ferroelectric thin film. In the above references, description is made of the nonvolatile memories a ferroelectric a capacitor. problems be however, are also DRAMs using a ferroelectric substance as For example, as described in xe2x80x9cFerroelectric Thin Film Technologyxe2x80x9d (published Science Forum, 1992), pages 13-16, for 256 Mb DRAM or the like, an attempt been made to use a crystal thin film made from a high dielectric constant material BaSrTiO3 or the like a capacitor. In above-described (1) (2), is difficult control the crystal grain size and orientation of the ferroelectric thin When such a ferroelectric thin film is patterned to form capacitor, variation in characteristics memory cells becomes large of large variation in crystal a variation and larger roughness of each of ferroelectric thin film and an This makes it difficult cells to equally obtain sufficient characteristics, giving rise a problem in exerting adverse effect on stability in manufacturing yield. In the above-described reference (3), a variation in is reduced; a variation in grain size of crystal grains a memory cell is a leakage current occurs, an effective voltage between capacitors reduced of concentration an electric field a grain boundary present in the in the thickness or uneven, which results in
 grain size is about 180 nm and a relAtive standArd deViaTioN oF cryStal Grain sizes is abOUt 15%.
(3) In A method of forming a thin fIlm deScRIbed IN JApaneSe PatenT laID-OpeN NO. HEi 7-142600, a CoMPoUnd of baTIO3 is forMed on a Pt thIn fIlM, whereby orieNTaTion of a ferRoeLectric thin fIlm Is contRoLleD By allOwiNg cryStal orIEntatiOn of the feRrOElectrIC thin fiLM To FollOw that of the Pt thin FIlM, To thereby ensurE remanEnT PoLARizAtiOn.
(4) In an orieNtEd ferROelectrIC tHIN FilM Described in JaPanese PatenT laiD-open NO. HEi 6-151601, aN EpitaxIal or OrIEntEd buffer layEr haVing a two-lAyer stRUcture oN A semicoNductoR siNglE crySTaL sUbsTrATe aND aN epITaxIal or oriEnTeD peroVskiTE abo3 typE feRroeLectrIc substance is ForMed tHEreOn, to oBtain A higHlY orieNted feRroelEcTric thin film.
In tHe abOve refereNceS, dEscRiPtion IS made oF thE noNvolatiLe memorIEs uSiNG A FeRroelectric substanCe AS A cApacitor. the proBLeMs TO be examiNeD, hoWeveR, ARe alsO preSEnT in DRAMs Using a FErRoElectriC sUbstanCe As a CapAcitoR.
(5) for eXample, As descriBed in XE2x80x9cFerroelectRIc Thin Film IntEGrATIoN techNolOgyxe2x80x9d (pubLishED by SCienCE FOruM, 1992), Pages 13-16, For a 256 MB DraM OR the like, an attempt haS bEen madE to usE a crystal thin Film made frOM A High dielEctrIC cONstant material Such aS BaSrTiO3 or THe like foR a capAcitor.
In The above-dESCribed reFerEncEs (1) aNd (2), iT IS dIfficult to conTROl thE cRystal gRaiN size anD orIenTatIon Of The ferroeLectric tHiN fIlM. WHen Such a FErroelecTrIc tHiN fiLm is pATterneD to foRm a mEmOrY CapAcitor, a VArIATion In ChAracTerIsTics bEtweEN meMory celLs becomes LarGE becAuSe Of a largE variation in cRyStal grain sIzE, a lArger vARIation in Crystal orientation, and a lARger surFacE rougHnesS of each of The FerroeLecTRic thiN film aNd an eLeCtrODE. This MAKeS it DiFficult for ALL of The meMoRy ceLls to eqUally obtain sufficiENt cHaracteristicS, giVing RISe To a PRoBLem In EXerTINg adverse effect On the stabiLiTY iN manufactuRIng YiEld.
In thE above-dEscriBEd referEnce (3), a variAtion in orIeNtatION is Reduced; howEver, sincE a variatiON in grAIn Size oF crYstal gRaIns In a meMory ceLL is Large, A leakaGe CurrenT occuRs, An effectIve voltage between capaciTors is ReducEd bEcause of cOncENtrAtion of an ElecTric field aT a gRaiN bounDarY PortiOn prESeNt iN The thIn fiLM in the filM ThIckNESs Direction, or REMAneNt polAriZAtion bEcomEs uneven, which resuLTs in
 grain size is about 180 n m and a re lativ e s tan da rd d evia tion of crysta l  gra in sizes is about 15%. 
(3)In a me t ho d offorming at h infi lm  de sc r ib ed in  Ja panesePatent Lai d-o pe n No. Hei 7- 1 42 600, a com pou nd of BaTiO3  is  forme dona  Pt t hin  film , wher e by ori entationof a ferr o electri c th in f ilm is controlled by allowing cryst al ori en t at i o n o f t he ferroel ec trict hin fil m  t o f oll o w that of the  Pt thin fi l m,to the re bye nsurereman en t  po larization. 
(4)  In an or iented ferroel e ctric t hin fi lmdes crib e din  Ja pa n ese Pa ten t  La id-openNo .Hei 6 -151 6 0 1 ,  anepi taxi al or  oriented buf fer  lay e r h aving  a tw o-la ye r str ucture  on a  s emiconductor si ngle  crystalsub st rat eand a n  epita xia l o r orien ted per o vsk it e A BO 3 type ferroelectr ic s ub stance i s form e dth e reon, to  o bta in a h ighly  ori e nt ed ferro electr i cth in film .In the  a bov e r efere n ces,  descr iption i s mad e  of the nonvol a tile memories us i n ga  fer roe lectric sub stan c e as  a c a pa cit o r. Th e pro bl e ms to be examined, how ev er, ar e als o present inDRAMs usin g a  ferroel ectr i cs ubstance as acapac itor.
(5)F or examp le, a s descri bed in xe 2 x 80x9cFer roe lec tri c T h i nFilm Integrat i o n Te ch nologyx e2x 80x9d ( pub lis hed  by  S cience Fo rum, 199 2) ,pa ge s 1 3-16, for a 25 6MbDR AMor th e  like,  an a ttem pt  h a s b een mad e  t o useacr ysta l t hi n fil m ma d e f rom a h igh diele ctr i c co ns ta nt mate rial such asBa SrTiO3 orth e l ike fo r a capaci tor.
In the above-descr i bed ref ere nces(1)and (2),itis dif fic u lt tocontro l the  c rys t a l gra i n  s ize  a nd orienta t i onof th eferr oelectr ic thin film. When suc h a ferroelec tri c th i n  f ilm is pat te r ned t o form a memory  capacitor ,a  v ariation i n  ch ar acteris tics be tween memorycells bec omes larg ebeca u s e o f a largevariatio n in crys t al gr a in  size , a  large rvar iatio n in c r yst al or ientat io n, and  a la rg er surfa ce roughness of each of  the f erroe lec tric thin  fi l m a nd an ele ctro de. This m ake s i t dif fic u lt fo r al l  o f t h e mem oryc ells to e q ua lly o bt ain suffici e n t  ch aract eri s tics,givi ng rise to a prob l em in exerting  adv e r seeff e ct o nthe stabilityinma n u facturin gyield.
In t he above -d e scrib ed ref erence  (3), a v ar i ationin o rie ntation i s r ed u ced; ho we ve r , sinc e ava riatio n in g r ains i ze of crystal gr ainsi n  a me m ory  cell  i s large ,  a l eakage cur rent occurs , an e ffec tivevoltage  b etween  ca pa citors isr educed be cause  of con ce ntra tio n of a n el e c tricfiel data grain b o u nd a ry  p o rti on p resen tin t he thin f i lm in th e f i lm thic kn ess d irecti o n, o r remanent  po lariz a t ion become s  une v en ,  whic h resu lts in 
 grain_size is_about 180 nm and_a relative_standard_deviation of_crystal_grain sizes is_about 15%.
(3) In_a method of forming_a thin film_described_in Japanese Patent Laid-open No. Hei 7-142600, a compound of BaTiO3 is formed on_a_Pt thin_film,_whereby_orientation of a ferroelectric thin_film is controlled by allowing_crystal orientation_of the ferroelectric thin film to follow that_of_the Pt thin_film, to thereby ensure remanent polarization.
(4) In an oriented_ferroelectric thin film described in Japanese_Patent Laid-open No._Hei_6-151601,_an epitaxial or oriented_buffer layer having a two-layer structure_on a semiconductor single crystal substrate_and an epitaxial or oriented perovskite ABO3_type ferroelectric substance is formed thereon,_to obtain a highly oriented_ferroelectric thin_film.
In the above references, description_is made of_the nonvolatile_memories using a_ferroelectric substance as a capacitor. The_problems to be_examined, however, are also present in_DRAMs_using a ferroelectric_substance_as_a capacitor.
(5)_For example, as_described_in xe2x80x9cFerroelectric_Thin_Film Integration Technologyxe2x80x9d (published by Science_Forum,_1992), pages 13-16, for a 256 Mb_DRAM or the like,_an_attempt has been made_to use a crystal thin_film made from a high dielectric_constant material_such as_BaSrTiO3 or the like for a capacitor.
In the above-described references (1)_and (2), it is difficult to_control the crystal grain_size and_orientation_of the ferroelectric_thin_film. When_such a ferroelectric thin film is patterned_to form_a memory capacitor, a variation in_characteristics between memory cells_becomes_large because of a large variation_in crystal grain size, a larger_variation in crystal orientation, and_a_larger_surface roughness of each of_the ferroelectric thin film and an_electrode. This makes_it difficult for all of the memory_cells_to equally obtain sufficient characteristics, giving_rise_to a problem in exerting adverse_effect_on_the stability in manufacturing yield.
In_the above-described reference (3), a variation_in orientation is reduced; however, since a variation in_grain size of_crystal grains in a memory_cell_is_large, a leakage current occurs, an effective voltage between capacitors_is reduced_because of concentration_of an electric field at a grain boundary portion present_in the thin film in the film_thickness direction, or remanent polarization becomes uneven, which results in