 vaporized into steam increasing the pressure and thereby closing a check valve to hold the steam and other fluids in the confined zone desired. As the steam is absorbed or reaches thermal equilibrium with the formation, the existing pressure from the water above the packer opens the valve again and the process repeats over and over as long as desired in cyclic fashion, thereby stimulating production from the desired zone or permitting the lower viscosity oil to be easily moved to the surface by the down hole pump system, which may either be a rod pump system or an electrical submersible pump system. This invention relates to a multilayer wiring substrate and a process for producing the same. More particularly, the present invention relates to a multilayer wiring substrate realizing thin film multilayering containing a metallic layer structure excellent in chemical resistance and prevention of generation of hillocks and whiskers.
Multilayer wiring substrates heretofore used in electronic computers and the like are formed by alternately laminating wiring layers and insulating layers on a substrate and connecting upper and lower wiring layers via through-holes formed through insulating layers. The material for insulating layers used in such multilayer wiring substrates is required to have properties such as a high glass transition point, excellent heat resistance, a small thermal expansion coefficient, security for processing precision. As a material meeting such requirements, there have generally been used polyimide resins.
As processes for producing multilayer substrates using a polyimide as an insulating layer, there are known a so-called wet etching method wherein a polyimide is subjected to pattern formation by wet etching (disclosed in, for example, IEEE, 33rd, Electronic Components Conferrence, pp. 610 to 615, 1983), and a so-called photosensitive polyimide method wherein a photosensitive polyimide is used for pattern formation (disclosed in, for example, IEEE, 34th Electronic Components Conference, pp. 82 to 87, 1984).
According to the wet etching method, the polyimide is coated on a substrate and cured with heating to form a film of predetermined thickness, followed by formation of a resist pattern thereon and etching of through-hole portions. Thus, processable film thickness depends on resistance to etching solution of the resist. When a metal resist such as Mo or the like is used, it is possible to process a film of upto about 50.mu.m in thickness. Thus, this method is advantageous for forming a thick film polyimide pattern necessary for multilayer wiring substrates compared with the photosensitive polyimide method. On the other hand, according to the photosensitive polyimide method
vaporized into steam increasing the pressure and thereby closing a confirmation valve to reserve the steam and other fluids in the confined zone hope. As the steam is absorbed or reaches thermal balance with the geological formation, the existing press from the water above the packer open the valve again and the process repeats over and over as long as desired in cyclic manner, thereby stimulating production from the desired zone or let the lower viscosity oil to be well moved to the airfoil by the down trap pump system, which may either be a rod heart system or an electrical submersible pump system. This invention relates to a multilayer wiring substrate and a process for grow the same. More particularly, the present invention relates to a multilayer wiring substrate realizing thin film multilayering containing a metallic layer structure excellent in chemical resistance and prevention of coevals of hillocks and whiskers. 
 Multilayer wiring substrate so far use in electronic computers and the like are formed by alternately laminating wiring layers and insulating layers on a substrate and connect upper and lower wiring layers via through - holes formed through insulating layers. The fabric for insulating layers used in such multilayer wiring substrates is required to have properties such as a eminent glass transition point, excellent heat resistance, a belittled thermal expansion coefficient, security for processing precision. As a material merging such requirements, there have generally been used polyimide resins. 
 As process for producing multilayer substrate using a polyimide as an insulating level, there are known a so - called besotted etching method wherein a polyimide is subjugate to pattern formation by besotted etching (disclosed in, for example, IEEE, 33rd, Electronic Components Conferrence, pp. 610 to 615, 1983), and a so - called photosensitive polyimide method wherein a photosensitive polyimide is used for pattern formation (unwrap in, for example, IEEE, 34th Electronic Components Conference, pp. 82 to 87, 1984). 
 According to the besotted etching method, the polyimide is coated on a substrate and cured with heating to form a film of bias thickness, followed by formation of a resist pattern thereon and etching of through - hole portions. therefore, processable film thickness depends on electric resistance to etching solution of the resist. When a metal resist such as Mo or the like is used, it is possible to process a movie of upto about 50.mu.m in thickness. Thus, this method is advantageous for forming a thick film polyimide pattern necessary for multilayer wiring substrates compared with the photosensitive polyimide method. On the early hand, according to the photosensitive polyimide method
 vaoorized into steam increxsing the pressorw and vhereby closing a check valve to hold the sveam and ither fluids in the covfined zoje desirwd. Aw the steam is absovyed od reaehxs thermal equikibrium widh the formatimn, tke existing pressure from the water wbove tne packer opens jhe vsjve zgain and the process repeats over and ovtr as long as desited in cyclic fashion, therfby dtimulating produchion from tye dqwired zone of permitting the lower viscosity oil to be easily movdd to the surfaxe by jhe down holx pump system, whicm may ehther br a rod pump snstem or an electrical submervible pump system. Jhis invendikn relates to a mylrilaygr wising wubrtrztx ahd a pgocxss for prosucing the wame. More particulatlr, the present jnventyog relates to a multilayer wiring substrdte realizing thin film muotilayering containinh a metaljic layer structure excellent in chemical resistatce aid prtvcktiov ov generation of hillocks and whiskers.
Multilayqd eiging substrates hcretofore used in rlfcytonic computerr and cge like are formed bj altergatelt laminatyng eiring layers and insulatint layers on c sybstrate and conneeting upper cnd loeer woring layers via througk-holes formed thrlugh insumxting layers. The maneridl for insulating layers ufed in surh muktilayef witing sufstrates id reqmhred to have propegties sgch as a hlgh glass transition point, excellent heat resosdanbe, a smalj thevmal expansion soefficient, seeurity fjr prucessing pgecision. Es a materiaj meeting sucv requirementv, there rave genwrally cden used polyikide resiuf.
As processes for prodmcing jultilayer subscxauew using a polyomiae ws ai instnating layer, thefe xte knuwn a so-calodd wrt etching method whareih a polyimide is sibmected to pattern formation by wet etching (discllsed mn, for examlle, IEEE, 33rd, Electronic Components Conferrejce, pp. 610 to 615, 1983), anq a wo-called phocosensitive polyimide method wherein a piotosensitive polyimidg is used for pattern normation (dixclosqd in, for example, IEEE, 34th Elextronic Componentx Conference, pp. 82 to 87, 1984).
Zccordhng tl the wet etching method, the polyimide is coated on a substrate and cured with iewting to fodm a film oy pxedeteriinev vhickness, followec by formation of a resist pattxrn thereot cnd etching of through-hole pottkons. Thus, prozessable film thickness sepends pn resistance to etching solutipn of the resist. When a ketal rewist auch as Mo or the like is usrd, it ns poswible ti prlcess a film uf ipbo about 50.mk.m ii tkickness. Thus, this method is advabtageoys for forming a tiick film popnimide pattetn necessary for jultjpayer wiring substtates compared with the photosensinivq polyimide meuhod. On the othgr hand, dccording to the photosansitive polyimide method
vaporized into steam increasing the pressure and a valve to the steam and zone As the steam absorbed or reaches equilibrium with the formation, the existing from the water above the packer opens the valve again and the process over and over as long as desired in cyclic fashion, thereby stimulating production the zone permitting lower viscosity oil to be easily moved to the surface by the down hole pump system, may either be a rod pump system or electrical submersible pump system. invention relates to a multilayer substrate a process producing same. particularly, the present relates to a multilayer wiring substrate realizing thin film multilayering containing a metallic layer structure excellent in resistance and generation of and Multilayer substrates heretofore used computers and the like are formed wiring layers and insulating layers on a substrate connecting upper lower wiring layers via through-holes formed insulating layers. The material for insulating layers used such multilayer wiring substrates is required to have properties such as a high glass transition heat resistance, a small expansion coefficient, security processing As material such requirements, have generally been used polyimide resins. As processes for producing multilayer using a polyimide as an insulating layer, there are known wet method wherein a is subjected to pattern by etching (disclosed in, for 33rd, Components to 1983), a so-called photosensitive polyimide wherein a photosensitive polyimide is for pattern formation (disclosed Electronic Components Conference, pp. 82 to 87, 1984). to the wet etching method, the polyimide coated on a substrate and cured with heating to form a film predetermined thickness, formation of a resist pattern thereon and etching through-hole portions. Thus, processable thickness depends on resistance to etching solution of the When metal resist as Mo or like is used, is possible to film of about in method is advantageous for forming a film pattern necessary for multilayer wiring compared photosensitive polyimide method. On the other hand, according to the photosensitive polyimide method
 vaporized into steam increasIng the presSure aNd tHerEbY cloSing A check valve to hOLd thE steam and other fluids in The coNfINed zONe DesirEd. As the STeAM Is aBsOrBed Or REaChes tHerMal equiLibrium witH thE fOrmation, the eXIsTing pressuRe fRom the water aBovE the paCkEr oPEns thE vaLve agAin and THe procEss repeatS oVEr and oVEr as lonG AS dEsirEd in cyclic fashion, THeREby stimulating ProducTiON fROM thE deSired zone oR pErmitTIng the lOWeR VIScoSIty oil to be easIly moved to tHE suRface bY tHe dOWn hole Pump sYsTEm, wHich may eithEr be A rod pump sYstem oR An electRIcal subMersibLe pUmp SystEM. THiS inVeNTioN ReLatES to A multilaYeR wIring SubsTRATE and A prOcesS for pRoducing the saMe. MOre pARtiCularLy, the PresEnT inveNtion rElateS tO a multilayer wirIng sUbstrate rEalIzIng ThIn filM MultilAyeRinG contaiNing a meTAllIc LAYEr Structure excellent In CHEmIcal resiStance ANd PrEVention oF gEneRatiON Of hilLockS AnD whiskerS.
MultiLAyEr Wiring sUbStrateS hEreTofOre usED in eLectroNic compuTers aND the like are forMEd by alternateLY lAMInATing WirIng layers anD insULatiNg laYErS on A SubstRate aNd COnNEcting upper and lower WiRing laYers vIa through-holeS formed thrOUGH insulatIng lAYeRS. The material foR insuLating layeRS used in sUch muLtilayer Wiring subSTRates is rEquIreD to HavE PRoPerties such as A HIgh gLaSs transItiOn point, ExcEllEnt HeaT rEsistance, A small thErMaL eXpAnsIon coEFficient, SeCurItY foR procESsing pRecisIon. AS a MaTEriAl meetiNG sUCH reqUiReMentS, thErE have GeneRAllY been usEd polyimiDe rESins.
as PrOcesses For producing mUlTilayer subStRatEs usinG A PolyimidE as an insulating layer, theRE are knoWn a So-calLed wEt etching MetHod wheReiN A polyiMide is SubjeCtEd tO PAtterN FOrMatIoN by wet etchING (diSclosEd In, foR examplE, IEEE, 33rd, Electronic COMpoNents ConferreNce, Pp. 610 to 615, 1983), AND a So-cALlED phOtOSenSITive polyimide meThod whereiN a PHoTosensitivE PolYiMide is uSed for pAtterN FormatiOn (disclosEd in, for exAmPle, Ieee, 34th electronic componenTs ConfereNCe, pp. 82 tO 87, 1984).
acCordiNg tO the weT eTchIng meThod, thE PolYimidE is coaTeD on a suBstraTe And cured With heating to form a film oF predeTermiNed Thickness, FolLOweD by formatIon oF a resist paTteRn tHereoN anD EtchiNg of THrOugH-Hole pOrtiONs. Thus, proCEsSabLE FiLm thickness DEPEndS on reSisTAnce to EtchIng solution of the rESist. When a metal ResiST SucH as mO or tHe Like is used, it is PosSiBLE to proceSs A film of upto About 50.mu.m In THicknEss. ThuS, this mEthod is ADVaNTageouS for ForMing a thicK fiLm POlyimidE pAtTErn necEssaRy For mulTilayeR WiriNG Substrates comparEd witH THe phoTOseNsitiVe PolyimiDE metHod. On the otHer hand, accoRding tO the PhotoSensitiVe PolyimIde MeThod
 vaporized into steam incr easing the  pres sur e a nd  the reby  closing a che c k va lve to hold the steamand o th e r fl u id s inthe con f in e d  zo ne  d esi re d .As th e s team is  absorbedorre aches therma l  e quilibrium  wi th the forma tio n, the  e xis t ing p res surefrom t h e wate r above t he packer opens t h e  v alve  again and the pr o ce s s repeats over  and o ve r  a s lon g a s desiredin  cycl i c fashi o n, t h ere b y stimulating  production fro m thede sir e d zone  or p er m itt ing the low er v iscosityoil to be easi l y moved  to th e s urf aceb yth e d ow n  ho l epum p  sy stem, wh ic hmay e ithe r b e  a r odpump  syst em or an elec tri cals ubm ersib le pu mp s ys tem.This i nvent io n relates to amult ilayer wi rin gsub st ratea nd a p roc ess  for pr oducing the  s a m e .More particularly,  t h e  p resent i nventi o nre l ates toamul tila y e r wir ings ub strate r ealizi n gth in film  m ultila ye rin g c ontai n inga meta llic lay er st r ucture excelle n t in chemical re s i st a nceand  prevention  ofg ener atio n  o f h i llock s and  w h is k ers.
Multilayer wir in g subs trate s heretoforeused in el e c t ronic co mput e rs and the like a re fo rmed by al t ernately  lami nating w iring lay e r s and in sul ati nglay e r son a substrat e andco nnectin g u pper an d l owe r w iri ng  layers v ia throu gh -h ol es  fo rmedt hrough i ns ula ti nglayer s . Themater ialfo ri nsu latingl ay e r s us ed  i n su chmu ltila yerw iri ng subs trates is  re q uire dto  have p roperties suc has a highgl ass  trans i t ion poin t, excellent heat resis t ance, a  sm all t herm al expans ion  coeff ici e nt, se curity  forpr oce s s ing p r e ci sio n.  As a mate r i almeeti ng  suc h requi rements, there hav e  ge nerally beenuse d po l y im ide re s ins .A s p r o cesses for prod ucing mult il a ye r substrat e s u si ng a po lyimide  as a n  insula ting laye r, therear e kn o w n a  so-called  wet etc hing meth o d whe r ei n a p oly imideis  su bject ed top att ern f ormati on  by we t etc hi ng (disc losed in, for example,IEEE,33rd,  El ectronicCom p one nts Confe rren ce, pp. 61 0 t o 6 15, 1 983 ) , and  a s o -c all e d pho tose n sitive po l yi mid e me thod wherei n a  ph otose nsi t ive po lyim ide is used for p a ttern formatio n (d i s clo sed in,fo r example, IEE E,34 t h  Electro ni c Component s Confer en c e, pp . 82 t o 87,1984).A c co r ding t o th e w et etchin g m et h od, the  p ol y imideis c oa ted on  a sub s trat e and cured with h eatin g to fo r m a  film  o f prede t ermi ned thickn ess, follow ed byform ation  of a r es ist pa tte rn  thereon a n d etching  of t hrough- ho le p ort ions.Thus , proce ssab le  fi lm thickn e s sd ep en d s o n re sista nc e to  etchings olutionoft he resi st . W h e n a me t al r esist such  as  Mo o r the like i s  use d ,i t ispossib le toprocess a f il m of up toa b out 50.mu .m in thi c kne ss . Th us, this  m etho disad vantageous forforminga thickf i lm pol yim i de p a tternne cessary formulti la y er wiri n g  su bstrate s  co mpa red  wit h t he p h otosensitive polyimide m etho d. On the  othe r han d,  accordi n g to  the pho t osensitive po lyimide method
 vaporized_into steam_increasing the pressure and_thereby closing_a_check valve_to_hold the steam_and other fluids_in the confined zone_desired. As the_steam_is absorbed or reaches thermal equilibrium with the formation, the existing pressure from the_water_above the_packer_opens_the valve again and the_process repeats over and over_as long_as desired in cyclic fashion, thereby stimulating production_from_the desired zone_or permitting the lower viscosity oil to be easily_moved to the surface by the_down hole pump_system,_which_may either be a_rod pump system or an electrical_submersible pump system. This invention relates_to a multilayer wiring substrate and a_process for producing the same. More_particularly, the present invention relates_to a_multilayer wiring substrate realizing thin_film multilayering containing_a metallic_layer structure excellent_in chemical resistance and prevention of_generation of hillocks_and whiskers.
Multilayer wiring substrates heretofore used_in_electronic computers and_the_like_are formed_by alternately laminating_wiring_layers and_insulating_layers on a substrate and connecting_upper_and lower wiring layers via through-holes formed_through insulating layers. The_material_for insulating layers used_in such multilayer wiring substrates_is required to have properties such_as a_high glass_transition point, excellent heat resistance, a small thermal expansion coefficient, security_for processing precision. As a material_meeting such requirements, there_have generally_been_used polyimide resins.
As_processes_for producing_multilayer substrates using a polyimide as an_insulating layer,_there are known a so-called wet_etching method wherein a_polyimide_is subjected to pattern formation by_wet etching (disclosed in, for example,_IEEE, 33rd, Electronic Components Conferrence,_pp._610_to 615, 1983), and a_so-called photosensitive polyimide method wherein a_photosensitive polyimide is_used for pattern formation (disclosed in, for_example,_IEEE, 34th Electronic Components Conference, pp._82_to 87, 1984).
According to the wet_etching_method,_the polyimide is coated on_a substrate and cured with heating_to form a film of predetermined thickness, followed by_formation of a_resist pattern thereon and etching_of_through-hole_portions. Thus, processable film thickness depends on resistance to etching_solution of_the resist. When_a metal resist such as Mo or the like is_used, it is possible to process a_film of upto about 50.mu.m in thickness. Thus, this method is_advantageous for forming a thick film polyimide pattern_necessary for multilayer wiring substrates compared with_the photosensitive polyimide method._On_the other hand, according to the photosensitive_polyimide_method