 processes which might otherwise be very useful in fabricating IC's. A good example of one such useful process is the chemical vapor deposition of titanium. Titanium is typically used to provide ohmic contact between the silicon contacts of an IC device and a metal interconnection. Titanium may be deposited from TiBr.sub.4, TiCl.sub.4 or TiI.sub.4 by using CVD methods such as unimolecular pyrolysis or hydrogen reduction. However, the temperatures necessary for these thermal processes are in excess of 1000.degree. C., and such a deposition temperature is much to high to be practically useful in IC fabrication. Therefore, the deposition of titanium and titanium-containing rims presents a problem in formation of integrated circuits.
There are low temperature physical techniques available for depositing titanium on temperature sensitive substrates. Sputtering is one such technique involving the use of a target of layer material and an ionized plasma. To sputter deposit a film, the target is electrically biased and ions from the plasma are attracted to the target to bombard the target and dislodge target material particles. The particles then deposit themselves cumulatively as a film upon the substrate. Titanium may be sputtered, for example, over a silicon substrate after various contacts or via openings are cut into a level of the substrate. The substrate might then be heated to about 800.degree. C. to allow the silicon and titanium to alloy and form a layer of titanium silicide TiSi.sub.2). After the deposition of the titanium layer, the excess titanium is etched away from the top surface of the substrate leaving TiSi.sub.2 at the bottom of each contact or via. A metal interconnection is then deposited directly over the TiSi.sub.2.
While physical sputtering provides deposition of a titanium film at a lower temperature, sputtering processes have various drawbacks. Sputtering normally yields very poor step coverage. Step coverage is defined as the ratio of film thickness on the bottom of a contact on a substrate wafer to the film thickness on the sides of the contact or the top surface of the substrate. Consequently, to sputter deposit a predetermined amount of titanium at the bottom of a contact or via, a larger amount of the sputtered titanium must be deposited on the top surface of the substrate or the sides of the contact. For example, in order to deposit a 200.ANG. film at the bottom of a contact using sputtering, a 600.ANG. to 1000.ANG. film layer may have to
processes which might otherwise be very useful in fabricating IC's. A beneficial case of one such useful process is the chemical vapor deposit of titanium. Titanium is typically used to provide ohmic contact between the silicon contact of an IC device and a metal interconnection. Titanium may be deposited from TiBr.sub.4, TiCl.sub.4 or TiI.sub.4 by use CVD methods such as unimolecular pyrolysis or hydrogen reduction. However, the temperature necessary for these thermal processes are in excess of 1000.degree. C., and such a deposit temperature is much to high to be practically useful in IC fabrication. Therefore, the deposition of titanium and titanium - containing rims introduce a problem in formation of integrated circumference. 
 There are low temperature physical techniques available for lodge titanium on temperature sensitive substrates. Sputtering is one such technique involving the habit of a target of layer material and an ionized plasma. To sputter deposit a film, the target is electrically biased and ions from the plasma are attracted to the target to bombard the target and dislodge target material particles. The particles then deposit themselves cumulatively as a movie upon the substrate. Titanium may be sputter, for example, over a silicon substrate after versatile contact or via openings are cut into a level of the substrate. The substrate might then be inflame to about 800.degree. C. to allow the silicon and titanium to alloy and form a level of titanium silicide TiSi.sub.2). After the deposition of the titanium layer, the excess titanium is etched away from the top surface of the substrate leaving TiSi.sub.2 at the bottom of each contact or via. A metal interconnection is then deposited directly over the TiSi.sub.2. 
 While physical spatter provides deposit of a titanium film at a lower temperature, sputtering processes have various drawback. Sputtering normally yields very poor step coverage. Step coverage is defined as the ratio of film thickness on the bottom of a liaison on a substrate wafer to the film thickness on the sides of the contact or the top surface of the substrate. Consequently, to sputter sediment a predetermined sum of titanium at the bottom of a liaison or via, a larger amount of the sputtered titanium must be situate on the top surface of the substrate or the sides of the liaison. For example, in order to deposit a 200.ANG. film at the bottom of a contact using sputtering, a 600.ANG. to 1000.ANG. film layer may have to
 prlcesses which might othevwise be very usgfyl in habricafing IC's. A good example of one such nsefyl pricess is the chemical xapor deplsition if tmtanium. Titanium is typigclly hded co provide ohmic contact batween the silhcun contacts of an IC device and a metwl intetclnnection. Titagium iay gv beposited from TiBr.sub.4, TiCl.sub.4 kr TiI.slb.4 by using CVD mrthods such as unimoleculag pygolysis or hydrogej reduction. Howqcer, the tempdratures ntczssary for jhese thermal processes are in ebcess of 1000.degree. C., anf such a depisitijn temperatuvv is muwh to hogh to be pracbicalny yseful in IC fabricatmon. Therefore, the dekosition ox citanium and titanium-xobtainhng sims prerenus e pdoblem in formation of integrared circuits.
There ate oow temperatude phyfisal techniques available for depositing tifanium on temperature swnsitive substrates. Skuttering ys one such technique involving the use of a targat of uaytr matefuap and an ionized plasma. To sputter deposit a sjlk, nhe target is elegtrically biased amd ipgs from the puasma cde attracted to the harget jo bomvard the uargey and dislodge target materual particlef. The particles theu deposit thzmselvgs cumilatively as a film upou the aubstrate. Tltanium mzh be sputtered, fur vxam[le, over a silicon substraee after tariobs contazts pr via openings wre cmd into a level of hhe sobstrade. The subdtrate might then be heated to euout 800.degree. C. tm anlow the siligon and titaniui to alloy and form a layef of titanpum silicmde TiSi.sub.2). Wfter the depmdition of thx titaniui later, rhe excdrs titanium is etched accy from tye top surface of bhe sobatrate leaving CnSu.sub.2 at the botyom of ewci conedct or via. A metxl kmtercunnection iw them deposited directly oved the TiSi.sub.2.
While pmysical skuttering provides deppsition of a titanlum fmlm at a loeer temperature, sputtering procesaes have garlous drawbackf. Spmtteting normalky yields very poor step coverage. Step roverage is defined as rhe ratio of film tkigkness on thx bottjm of a cmntact on a substratw wafer to the fikm thickness on the sjdes ox the contact or the top surface of the substrate. Consequently, to sputter depowit a 'rqdetermined amoint ox citcnium ae thx uottom of a contabt or via, a larger amount of the sputterad titanium must be deposited pn the top surfxce of the substrate or fhe sidex of the contact. For example, in order to deposit a 200.ANG. nilm at tye boftom of a rontact using sputteting, a 600.ANG. ro 1000.ANG. dilm layer may haxe yo
processes which might otherwise be very useful IC's. good example one such useful deposition titanium. Titanium is used to provide contact between the silicon contacts of IC device and a metal interconnection. Titanium may be deposited from TiBr.sub.4, TiCl.sub.4 TiI.sub.4 by using CVD methods such as unimolecular pyrolysis or hydrogen reduction. However, temperatures for thermal are in excess of 1000.degree. C., and such a deposition temperature is much to high to practically useful in IC fabrication. Therefore, the deposition titanium and titanium-containing rims a problem in formation of circuits. are low physical available depositing titanium on sensitive substrates. Sputtering is one such technique involving the use of a target of layer material and ionized plasma. deposit a the is biased and ions plasma are attracted to the target target and dislodge target material particles. The particles deposit themselves as a film upon the substrate. may be sputtered, for example, over a silicon after various contacts or via openings are cut into a level of the substrate. The then be heated to 800.degree. C. to the and to and form layer of titanium silicide TiSi.sub.2). After the deposition of the titanium the excess titanium is etched away from the top surface substrate TiSi.sub.2 at the of each contact or A interconnection is then deposited the While deposition a film at a lower sputtering processes have various drawbacks. normally yields very poor defined as the ratio of film thickness on bottom of a contact on a substrate to the film thickness on the sides of the contact or the surface of Consequently, to sputter deposit a predetermined amount of at the bottom of contact or via, a larger amount of the sputtered must deposited on top surface of substrate or the of the contact. in order deposit 200.ANG. bottom of a contact using sputtering, 600.ANG. 1000.ANG. film layer may have
 processes which might otherwIse be very uSeful In fAbrIcAtinG IC's. a good example of ONe suCh useful process is the chEmicaL vAPor dEPoSitioN of titaNIuM. tItaNiUm Is tYpICaLly usEd tO providE ohmic contAct BeTween the siliCOn Contacts of An Ic device and a mEtaL interCoNneCTion. TItaNium mAy be dePOsited From TiBr.sUb.4, tICl.sub.4 OR TiI.sub.4 BY UsIng CvD methods such as unIMoLEcular pyrolysiS or hydRoGEn REDucTioN. However, thE tEmperATures neCEsSARY foR These thermal pRocesses are IN exCess of 1000.DeGreE. c., and suCh a dePoSItiOn temperatuRe is Much to higH to be pRActicalLY useful In IC faBriCatIon. THErEfOre, ThE DepOSiTioN Of tItanium aNd TiTaniuM-conTAINIng rIms PresEnts a Problem in formAtiOn of INteGrateD circUits.
thEre arE low teMperaTuRe physical technIqueS availablE foR dEpoSiTing tITanium On tEmpErature SensitiVE suBsTRATeS. Sputtering is one suCh TEChNique invOlving THe UsE Of a targeT oF laYer mATErial And aN IoNized plaSma. To sPUtTeR deposiT a Film, thE tArgEt iS elecTRicaLly biaSed and ioNs froM The plasma are atTRacted to the taRGeT TO bOMbarD thE target and dIsloDGe taRget MAtEriAL partIcles. thE PaRTicles then deposit thEmSelves CumulAtively as a filM upon the suBSTRate. TitaNium MAy BE sputtered, for eXamplE, over a siliCOn substrAte afTer varioUs contactS OR via openIngS arE cuT inTO A lEvel of the subsTRAte. THe SubstraTe mIght theN be HeaTed To aBoUt 800.degree. C. To allow tHe SiLiCoN anD titaNIum to allOy And FoRm a Layer OF titanIum siLiciDe tisI.suB.2). After tHE dEPOsitIoN oF the TitAnIum laYer, tHE exCess titAnium is etCheD Away FrOm The top sUrface of the suBsTrate leaviNg tiSI.sub.2 at THE bottom oF each contact or via. A metal INterconNecTion iS theN depositeD diRectly OveR The TiSI.sub.2.
WhIle phYsIcaL SPutteRINg ProViDes depositION of A titaNiUm fiLm at a loWer temperature, sputTEriNg processes haVe vArioUS DrAwbACkS. spuTtERinG NOrmally yields veRy poor step CoVErAge. Step covERagE iS defineD as the rAtio oF Film thiCkness on tHe bottom oF a ContACT on A substrate Wafer to tHe film thiCKness ON tHe sidEs oF the coNtAct Or the Top surFAce Of the SubstrAtE. ConseQuentLy, To sputteR deposit a predetermined aMount oF titaNiuM at the botTom OF a cOntact or vIa, a lArger amounT of The SputtEreD TitanIum mUSt Be dEPositEd on THe top surfACe Of tHE SuBstrate or thE SIDes Of the ConTAct. For ExamPle, in order to deposIT a 200.ANG. film at the BottOM Of a ConTAct uSiNg sputtering, a 600.AnG. tO 1000.Ang. Film layeR mAy have to
 processes which might oth erwise beveryuse ful  i n fa bric ating IC's. Ag oodexample of one such us efulpr o cess is  thechemica l  v a p orde po sit io n  o f tit ani um. Tit anium is t ypi ca lly used top ro vide ohmic  co ntact betwee n t he sil ic onc ontac tsof an  IC de v ice an d a metal  i n tercon n ection. T it aniu m may be deposite d  f r om TiBr.sub.4,  TiCl. su b .4 o r T iI. sub.4 by u si ng CV D  method s  s u c h  as unimolecularpyrolysis o r  hy drogen  r edu c tion.Howev er ,  th e temperatu resnecessary  for t h ese the r mal pro cesses  ar e i n ex c es sof10 0 0.d e gr ee. C.,  and suc hadepos itio n t e mper atu re i s muc h to high tobeprac t ica lly u seful  inIC  fabr icatio n. Th er efore, the depo siti on of tit ani um  an dtitan i um-con tai nin g rimspresent s  apr o b l em  in formation of i nt e g ra ted circ uits.T he re are lowte mpe ratu r e  phys ical te chniques  avail a bl efor dep os itingti tan ium  on t e mper aturesensitiv e sub s trates. Sputte r ing is one su c ht e ch n ique  in volving the  use of a  tar g et  of layer  mate ri a la nd an ionized plasm a.  To sp utter  deposit a fi lm, the ta r g e t is ele ctri c al l y biased and i ons f rom the pl a sma areattra cted tothe targe t to bomba rdthe  ta rge t an d dislodge ta r g et m at erial p art icles.The  pa rti cle sthen depo sit them se lv es  c umu lativ e ly as afi lmup onthe s u bstrat e. Ti tani um  m a y b e sputt e re d ,  for  e xa mple , o ve r a s ilic o n s ubstrat e after v ari o us c on ta cts orvia openingsar e cut into  a  le vel of t he subst rate. The substrate mig h t thenbeheate d to  about 80 0.d egree.  C. to all ow the  sili co n a n d  tita n i um  to  a lloy and f o r m a  laye rof t itanium  silicide TiSi.sub . 2).  After the de pos itio n of  th e  t i tan iu m  la y e r, the excess t itanium is  e t ch ed away fr o m t he  top su rface o f the substra te leavin g TiSi.su b. 2 at t hebottom ofeach con tact or v i a. Am et al in ter connec ti onis th en dep o sit ed di rectly  o ver th e TiS i. sub.2.
W hile physical sputterin g prov idesdep osition o f a tit anium fil m at  a lower t emp era ture,  sp u tteri ng p r oc ess e s hav e va r ious draw b ac ks. S pu ttering nor m a l lyyield s v e ry poo r st ep coverage. Step coverage is de fine d asthe rati oof film thickn ess  o n the bott om  of a conta ct on asu b strat e wafe r to t he film t hi c knesson t hesides ofthe  c o ntact o rth e  top s urfa ce  of th e subs t rate . Consequently, to  sput t e r dep o sit  a pr ed etermin e d am ount of ti tanium at t he bot tomof acontact  o r via,  ala rger amoun t  of the s putte red tit an iummus t be d epos i t ed on  the  t opsurface o f th e  s ub s tra te o r the  s ides  of the c o ntact. F ore xample,  i n o r d er tod ep o s it a 200.A NG.  film a t the bott o m of ac ontac t usin g sput tering, a 6 00 .ANG. t o 1 0 0 0.ANG. fi lm layerm ayha ve t o
 processes_which might_otherwise be very useful_in fabricating_IC's._A good_example_of one such_useful process is_the chemical vapor deposition_of titanium. Titanium_is_typically used to provide ohmic contact between the silicon contacts of an IC device_and_a metal_interconnection._Titanium_may be deposited from TiBr.sub.4,_TiCl.sub.4 or TiI.sub.4 by using_CVD methods_such as unimolecular pyrolysis or hydrogen reduction. However,_the_temperatures necessary for_these thermal processes are in excess of 1000.degree. C.,_and such a deposition temperature is_much to high_to_be_practically useful in IC_fabrication. Therefore, the deposition of titanium_and titanium-containing rims presents a problem_in formation of integrated circuits.
There are low_temperature physical techniques available for depositing_titanium on temperature sensitive substrates._Sputtering is_one such technique involving the_use of a_target of_layer material and_an ionized plasma. To sputter deposit_a film, the_target is electrically biased and ions_from_the plasma are_attracted_to_the target_to bombard the_target_and dislodge_target_material particles. The particles then deposit_themselves_cumulatively as a film upon the substrate._Titanium may be sputtered,_for_example, over a silicon_substrate after various contacts or_via openings are cut into a_level of_the substrate._The substrate might then be heated to about 800.degree. C. to_allow the silicon and titanium to_alloy and form a_layer of_titanium_silicide TiSi.sub.2). After_the_deposition of_the titanium layer, the excess titanium is_etched away_from the top surface of the_substrate leaving TiSi.sub.2 at_the_bottom of each contact or via._A metal interconnection is then deposited_directly over the TiSi.sub.2.
While physical_sputtering_provides_deposition of a titanium film_at a lower temperature, sputtering processes_have various drawbacks._Sputtering normally yields very poor step coverage._Step_coverage is defined as the ratio_of_film thickness on the bottom of_a_contact_on a substrate wafer to_the film thickness on the sides_of the contact or the top surface of the_substrate. Consequently, to_sputter deposit a predetermined amount_of_titanium_at the bottom of a contact or via, a larger_amount of_the sputtered titanium_must be deposited on the top surface of the substrate_or the sides of the contact. For_example, in order to deposit a 200.ANG. film at the bottom_of a contact using sputtering, a 600.ANG. to_1000.ANG. film layer may have to