 developed having even lower dielectric constants, such as insulation material sold by Applied Materials, Inc., the present assignee, under the trademarks Black Diamond I (dielectric constant of <3.0) and Black Diamond II (dielectric constant of <2.6). These materials with such low dielectric constants provide very good electrical performance with minimum capacitive coupling between interconnect layers. Unfortunately, their mechanical properties are inferior to those of silicon dioxide because these materials tend to be porous and therefore are not as hard as silicon dioxide. This is a particularly difficult problem because the insulator layer deposited over an interconnect layer tends to form a very uneven top surface and must therefore be smoothed to a plane surface by chemical mechanical polishing. While silicon dioxide is a sufficiently hard material to be relatively impervious to flaking or cracking during chemical mechanical polishing, porous materials with low dielectric constant can be susceptible to damage during chemical mechanical polishing.
Therefore, what is needed is a hard insulator material having a low dielectric constant that can reliably withstand chemical mechanical polishing. Currently available insulator materials suitable for use in multiple interconnect layers of integrated circuits are either porous and weak or else have a relatively high dielectric constant. 1. Field of the Invention
The present invention pertains to advancing material of indeterminate length through an arcuate guide on a cushion of pressurized air. The material is floatingly advanced through the guide without flutter or vibration.
2. Description of the Prior Art
The invention pertains to contactless turning guides for a running web and for guiding and controlling a running web through a change of direction. These turning guides are also commonly referred to as air rolls or air turns and are formed as a partial drum-like member having an arcuately curved surface which can be variable as to it transverse length and also variable as to the length of its arc. These prior art turning guides have a transverse nozzle slot at both the beginning and end of the arcuate path for supplying pressurized air to the air cushion located between the slots over the arcuately curved surface. Prior art contactless turning guides for running webs are disclosed in U.S. Pat. No. 4,182,472 issued on Jan. 8, 1980 and U.S. Pat. No. 4,282,998 issued on Aug. 11, 1981, both to Peekna. Other prior art contactless turning guides are shown in U.S. Pat. No. 4,197,972 which issued Apr. 15, 1980 to Robert A. Daane; U.S. Pat. No. 4
developed having even lower dielectric constants, such as insulating material fabric betray by Applied Materials, Inc., the present assignee, under the trademarks Black Diamond I (dielectric constant of < 3.0) and Black Diamond II (dielectric constant of < 2.6). These fabric with such humble dielectric constants provide very adept electric performance with minimum capacitive coupling between interconnect layers. Unfortunately, their mechanical properties are deficient to those of silicon dioxide because these materials tend to be porous and consequently are not as hard as silicon dioxide. This is a particularly difficult problem because the insulator layer deposited over an interconnect level tends to form a very uneven top airfoil and must therefore be smoothed to a airplane surface by chemical mechanical shining. While silicon dioxide is a sufficiently hard material to be relatively impervious to flaking or cracking during chemical mechanical polishing, porous materials with humble dielectric constant can be susceptible to damage during chemical mechanical polishing. 
 Therefore, what is needed is a hard insulator fabric hold a low dielectric constant that can reliably withstand chemical mechanical polishing. Currently available insulator materials suitable for use in multiple interconnect layer of integrated circuits are either holey and fallible or else receive a relatively high dielectric constant. 1. Field of the Invention 
 The present invention refer to advancing material of indeterminate length through an arcuate template on a cushion of pressurized air. The material is floatingly advanced through the guide without flutter or oscillation. 
 2. Description of the Prior Art 
 The invention pertains to contactless turning guides for a running world wide web and for guiding and control a running web through a change of direction. These turning scout are also commonly referred to as air rolls or air turns and are formed as a fond drum - like member having an arcuately curved open which can be variable as to it transverse duration and also varying as to the length of its arc. These anterior art turning guides have a transverse beak slot at both the beginning and end of the arcuate way for supplying pressurized air to the air shock absorber located between the slots over the arcuately curved surface. anterior art contactless turning guides for running webs are disclosed in U.S. Pat. No. 4,182,472 issue on Jan. 8, 1980 and U.S. Pat. No. 4,282,998 issued on Aug. 11, 1981, both to Peekna. Other prior art contactless turning guides are usher in U.S. Pat. nobelium. 4,197,972 which issue Apr. 15, 1980 to Robert A. Daane; U.S. Pat. No. 4
 degeloped having even lowev dielectric constants, vuch aa insulagion material sold by Appliev Mareriaos, Inc., the present asskgnee, undvr the trqdemerks Black Diamois I (dielectrid convvant of <3.0) and Blsck Diamong II (dielectriw zoustant of <2.6). These materials with such low dirlfctric constanjs prpdide nevy good electrical performance wjth minpmum capacitive cpupling between interconneft lwyers. Unfortunatelj, their mecyanisql propertier are infegnor to thosg of silicon dioxide because there macerials tene ro hg porous and thervfore are not as hard as silocon dioxide. Tmis iv a particularly difficunt problem because the insunacor layer deposited ocee an hntesconvwct lagec tsnds tl fkrm a very uneven top surface and must tnewvgore be smoofhed tj w plane surface by chemical mechanical kolisging. While silicon dioxude is a sufficiently hard matqrial to be relatively impervious to flaking or csackiig duxlkg cfwmlcal mechanical polishing, porous materials wieg koe dielectric cjnstant can bf xosceptible to aamage duding chemical mechwnical kolishung.
Therefjre, ehat is needed is a hard inwulator mategial having a low dielzctric constcnt thst cam reliably withstand chzmical mechanical polishinf. Currently availxblv invulator materials suitable for use mn muktiple kntetconnece layers ov intccrated circuits arf eitker pmrous and aeak or else have a relatively imgh dielectriv wonvtant. 1. Fneld on the Invention
Ehe present inrention 'ertaivs to advahcing meterial of igdeterminate ngngth through an arcuwte tuidw on a zjshion of presxurized apr. The material is floatlngly zdvanced througk uhw guide withouy fuuteeg oc vibwdtion.
2. Descri[tiov ow the Orior Art
Thc ivvenyion pertains to condactmess turning guidex nor a runbing web and for guidong and controllinh a rnnning web yhrjugh a change of direction. Theae turninh gmides are alsj conmonly referxed to as air rolls or air turns and are formed as a partiql drum-like member kaying an arcuetely surved susface which can be vqriable as to it uransverse length and amso vasiablf as to the length of its arc. These prior art turning guides have a transcerse ioszle slot af boyh thv bzgiuning agd eid of the arcuate iath for supplying pressurized amr to the dix cushion located between the suots over the arcuately curved surfacs. Prior srt contactless turning guides gor running webs are disglosed in U.S. Pzt. No. 4,182,472 issned on Jan. 8, 1980 and U.S. Lat. No. 4,282,998 issyed on Qug. 11, 1981, both to Peeyna. Obher prior art ckntactless turning guides are shiwn in U.D. Pat. No. 4,197,972 which mssued Apr. 15, 1980 uo Robett A. Daage; U.S. Pat. No. 4
developed having even lower dielectric constants, such material by Applied Inc., the present Diamond (dielectric constant of and Black Diamond (dielectric constant of <2.6). These materials such low dielectric constants provide very good electrical performance with minimum capacitive coupling interconnect layers. Unfortunately, their mechanical properties are inferior to those of silicon dioxide these tend be and therefore are not as hard as silicon dioxide. This is a particularly difficult problem because insulator layer deposited over an interconnect layer tends form a very uneven surface and must therefore be to plane surface chemical polishing. silicon dioxide is sufficiently hard material to be relatively impervious to flaking or cracking during chemical mechanical polishing, porous materials low dielectric be susceptible damage chemical polishing. Therefore, what is a hard insulator material having constant that can reliably withstand chemical mechanical polishing. available insulator suitable for use in multiple interconnect of integrated circuits are either porous and weak else have a relatively high dielectric constant. 1. Field of the Invention The present invention advancing material of indeterminate through an arcuate on cushion pressurized The material floatingly advanced through the guide without flutter or vibration. 2. Description the Prior Art The invention pertains to contactless turning guides running and for guiding controlling a running web a of direction. These turning also referred rolls air and are formed as partial drum-like member having an curved surface which can transverse length and also variable as to the of its arc. These prior art turning have a transverse nozzle slot at both the beginning and end of arcuate path pressurized air to the air cushion located between slots over the arcuately surface. Prior art contactless turning guides for running webs disclosed U.S. Pat. 4,182,472 issued on 8, 1980 and Pat. No. 4,282,998 Aug. 11, both Peekna. contactless turning guides are shown in Pat. 4,197,972 which issued Apr. 15, to Daane; U.S. Pat. No. 4
 developed having even lower dIelectric cOnstaNts, SucH aS insUlatIon material solD By ApPlied Materials, Inc., the prEsent AsSIgneE, UnDer thE trademARkS bLacK DIaMonD I (DIeLectrIc cOnstant Of <3.0) and Black diaMoNd II (dielectrIC cOnstant of <2.6). THesE materials wiTh sUch low DiEleCTric cOnsTants ProvidE Very goOd electriCaL PerforMAnce witH MInImum Capacitive couplinG BeTWeen interconneCt layeRs. uNfORTunAteLy, their mecHaNical PRopertiES aRE INfeRIor to those of sIlicon dioxiDE beCause tHeSe mATerialS tend To BE poRous and therEforE are not as Hard as SIlicon dIOxide. ThIs is a pArtIcuLarlY DiFfIcuLt PRobLEm BecAUse The insulAtOr Layer DepoSITED oveR an InteRconnEct layer tends To fOrm a VEry UneveN top sUrfaCe And muSt therEfore Be Smoothed to a planE surFace by cheMicAl MecHaNical POlishiNg. WHilE silicoN dioxidE Is a SuFFICiEntly hard material tO bE RElAtively iMperviOUs To FLaking or CrAckIng dURIng chEmicAL mEchanicaL polisHInG, pOrous maTeRials wItH loW diElectRIc coNstant Can be susCeptiBLe to damage duriNG chemical mechANiCAL pOLishIng.
therefore, whAt is NEedeD is a HArD inSUlatoR mateRiAL hAVing a low dielectric cOnStant tHat caN reliably withStand chemiCAL MechanicAl poLIsHIng. Currently avAilabLe insulatoR MaterialS suitAble for uSe in multiPLE intercoNneCt lAyeRs oF INtEgrated circuiTS Are eItHer poroUs aNd weak oR elSe hAve A reLaTively higH dielectRiC cOnStAnt. 1. field OF the InveNtIon
thE prEsent INventiOn perTainS tO aDVanCing matERiAL Of inDeTeRminAte LeNgth tHrouGH an Arcuate Guide on a cUshIOn of PrEsSurized Air. The materiaL iS floatinglY aDvaNced thROUgh the guIde without flutter or vibrATion.
2. DesCriPtion Of thE Prior Art
the InventIon PErtainS to conTactlEsS tuRNIng guIDEs For A rUnning web aND For GuidiNg And cOntrollIng a running web throUGh a Change of direcTioN. TheSE TuRniNG gUIdeS aRE alSO Commonly referreD to as air roLlS Or Air turns anD Are FoRmed as a Partial Drum-lIKe membeR having an Arcuately CuRved SURfaCe which can Be variabLe as to it tRAnsveRSe LengtH anD also vArIabLe as tO the leNGth Of its Arc. TheSe Prior aRt turNiNg guides Have a transverse nozzle slOt at boTh the BegInning and End OF thE arcuate pAth fOr supplyinG prEssUrizeD aiR To the Air cUShIon LOcateD betWEen the sloTS oVer THE aRcuately curVED SurFace. PRioR Art conTactLess turning guides FOr running webs aRe diSCLosEd iN u.S. PaT. NO. 4,182,472 issued on Jan. 8, 1980 anD U.S. paT. nO. 4,282,998 issued oN AUg. 11, 1981, both to PeeKna. Other PrIOr art ContacTless tUrning gUIDeS Are shoWn in u.S. PAt. No. 4,197,972 which IssUeD apr. 15, 1980 to RoBeRt a. daane; U.s. Pat. no. 4
 developed having even low er dielect ric c ons tan ts , su ch a s insulation m a teri al sold by Applied Mat erial s, Inc. ,  t he pr esent a s si g n ee,  u nd erth e  t radem ark s Black  Diamond I  (d ie lectric cons t an t of <3.0)  an d Black Diam ond  II (d ie lec t ric c ons tantof <2. 6 ). The se materi al s  withs uch low d ie lect ric constants pro v id e  very good ele ctrica lp er f o rma nce  with mini mu m cap a citivec ou p l i ngb etween interc onnect laye r s.Unfort un ate l y, the ir me ch a nic al properti es a re inferi or tot hose of silicon  dioxi debec ause th es e m at e ria l sten d  to  be poro us  a nd th eref o r e arenot  ashardas silicon di oxi de.T his  is a  part icul ar ly di fficul t pro bl em because theinsu lator lay erde pos it ed ov e r an i nte rco nnect l ayer te n dsto f o rm  a very uneven top  s u r fa ce and m ust th e re fo r e be smo ot hed  toa plane  sur f ac e by che micalm ec ha nical p ol ishing .Whi lesilic o n di oxideis a suf ficie n tly hard mater i al to be rela t iv e l yi mper vio us to flaki ng o r  cra ckin g  d uri n g che mical  m e ch a nical polishing, po ro us mat erial s with low di electric c o n s tant can  bes us c eptible to dam age d uring chem i cal mech anica l polish ing.
Ther e f ore, wha t i s n eed edi s  a  hard insulat o r  mat er ial hav ing  a lowdie lec tri c c on stant tha t can re li ab ly  w ith stand chemical  m ech an ica l pol i shing.  Curr entl yav a ila ble ins u la t o r ma te ri alssui ta ble f or u s e i n multi ple inter con n ectla ye rs of i ntegrated cir cu its are ei th erporous a nd weakor else have a relative l y highdie lectr ic c onstant.1.Fieldoft he Inv ention 
Thepr ese n t  inve n t io n p er tains to a d v anc ing m at eria l of in determinate length thr ough an arcua teguid e on  ac us h ion  o f  pr e s surized air. Th e material  i s  f loatinglya dva nc ed thro ugh the  guid e  withou t flutter  or vibra ti on.2 .  De scriptionof the P rior ArtT he in v en tionper tainsto  co ntact less t u rni ng gu ides f or  a run ningwe b and fo r guiding and controlli ng a r unnin g w eb throug h a cha nge of di rect ion. These  tu rni ng gu ide s  arealso co mmo n ly re ferr e d to as a i rrol l s  o r air turns a n d a re fo rme d  as apart ial drum-like mem b er having an a rcua t e lycur v ed s ur face which can  be  v a r iable as  t o it transv erse len gt h  andalso v ariabl e as to t he length  ofits  arc. The sepr i or arttu rn i ng gui desha ve a t ransve r se n o z zle slot at both  theb e ginni n g a nd en dof thea rcua te path fo r supplying  press uriz ed ai r to th eair cu shi on  located b e tween the  slot s overth e ar cua tely c urve d surfa ce.Pr ior  art cont a c tl e ss  t u rni ng g uides  f or r unning we b s are di scl o sed inU. S.P a t. No. 4, 1 8 2,472 issu edon Ja n .  8, 1980 a n d U. S .P at. N o. 4,2 82,998  issued onAu g. 11,198 1 ,  both toPeekna. O t her  p rior  art con ta ctle ss  tu rn ing guides areshown in  U.S. Pa t .  No. 4 ,19 7 ,972 whichis sued Apr. 15 , 198 0t o Rober t A.Daane;U .S.  Pa t.No.4
 developed_having even_lower dielectric constants, such_as insulation_material_sold by_Applied_Materials, Inc., the_present assignee, under_the trademarks Black Diamond_I (dielectric constant_of_<3.0) and Black Diamond II (dielectric constant of <2.6). These materials with such low_dielectric_constants provide_very_good_electrical performance with minimum capacitive_coupling between interconnect layers. Unfortunately,_their mechanical_properties are inferior to those of silicon dioxide_because_these materials tend_to be porous and therefore are not as hard_as silicon dioxide. This is a_particularly difficult problem_because_the_insulator layer deposited over_an interconnect layer tends to form_a very uneven top surface and_must therefore be smoothed to a plane_surface by chemical mechanical polishing. While_silicon dioxide is a sufficiently_hard material_to be relatively impervious to_flaking or cracking_during chemical_mechanical polishing, porous_materials with low dielectric constant can_be susceptible to_damage during chemical mechanical polishing.
Therefore, what_is_needed is a_hard_insulator_material having_a low dielectric_constant_that can_reliably_withstand chemical mechanical polishing. Currently available_insulator_materials suitable for use in multiple interconnect_layers of integrated circuits_are_either porous and weak_or else have a relatively_high dielectric constant. 1. Field of_the Invention
The_present invention_pertains to advancing material of indeterminate length through an arcuate guide_on a cushion of pressurized air._The material is floatingly_advanced through_the_guide without flutter_or_vibration.
2. Description_of the Prior Art
The invention pertains to_contactless turning_guides for a running web and_for guiding and controlling_a_running web through a change of_direction. These turning guides are also_commonly referred to as air_rolls_or_air turns and are formed_as a partial drum-like member having_an arcuately curved_surface which can be variable as to_it_transverse length and also variable as_to_the length of its arc. These_prior_art_turning guides have a transverse_nozzle slot at both the beginning_and end of the arcuate path for supplying pressurized_air to the_air cushion located between the_slots_over_the arcuately curved surface. Prior art contactless turning guides for_running webs_are disclosed in_U.S. Pat. No. 4,182,472 issued on Jan. 8, 1980 and_U.S. Pat. No. 4,282,998 issued on Aug._11, 1981, both to Peekna. Other prior art contactless turning guides_are shown in U.S. Pat. No. 4,197,972 which_issued Apr. 15, 1980 to Robert A._Daane; U.S. Pat. No._4