GB2329522A - Electromagnetic alignment and scanning apparatus - Google Patents

Abstract

A scanning type exposure apparatus which exposes a pattern of a mask onto an object while a stage 14 is moved in a scanning direction comprises apparatus capable of high accuracy position and motion control using one or more linear commutated motors to move a stage 14 in one long linear direction and a small yaw rotation in plane. One element of the linear commutated motor is mounted upon a drive frame 22, called a balancing portion, which moves in the opposite direction to the stage by a reaction force to maintain the centre of gravity of the apparatus. The balancing portion is heavier than the stage. The balancing portion and stage may be freely suspended above the base by air bearings 32 and 48. A laser interferometry system LBX1, LBX2, LBY, 50X1, 50X2, 50Y detects the exact position and orientation of the stage. A carrier/follower 60 holding a single voice coil motor 70 is controlled to follow the stage in the linear motion direction.

Description

2329522 - 1 A-ND SCANNING APPI-I-RATUS The nresent- invention relates zo a

movable Stac-e as-,aratus caDalble of Drec-ise rnovement, relates to a stawe ani:)aratus movable iIn one linear d--'Lre--t-on cauable of hJch accuracy positioning and hign sDeed movement, which can be esoecJa-ilv favorably util.;:_zed in a microlithographic system.

-,0 In wafer step-Ders, the alian-menz of an exiDosure field to the reticle being imasred affects tn. success of the circuit of thaz field. in a scannin- ex-Dosure system, d - reticle and wafer are moved simultaneously and scanned across one another during the exposure seguence. Thils is invention discloses an a::)-jaratus to ac--e-je precise scanning motion for such a system.

To attain hich accuracy, the sta=e should be isolated from mechanical disturbances.

This -4s achieved by employing electromagnetic forces to position and move the 0 stage. It should also have high control bandwidth, recuires that the stage be a light, structure with no moving parts. -Furt-her-incre, the sta-e should be free from excessive heat generation which m='-.z ca-se -interferoT,.ezer interference or mech-anicall chances that cc-,nn--oT,..-ises al-icnment accuracy.

Commutato--less electronacnet--,c such as the ones d.::_sclosed in U.S. Pat. IN--s.,506,204-1 ,506,205 and 4,507,597 are not feasible because they is require the manufacture of large magnet and coil asseruD!ies that are not com-mercially available. The weight o'l-' the stage and the heat generated also render these designs -naoiDropria-Le for ac. cu. racy applications.

ZL-1 im-0rovement over these commutatorless apparatuses was disclosed in U.S. Pat. No. 4,952,858, which em-ploys a conventional XY mechanilcally guided sub-stage to provide the larwe d-s-j'-,aceTient motion in the plane, thereby e1 the need _or larce magnet and coil asse-,,'Di-es. The electromacnetilc means mounted or. the sub-stage isolates the stace -from mechanical disturbances. Nevertheless, the combined weight o1E the sub-stage and stage still results'in low control bandwidth and the heat generated by the electromagnetic elements supporting the stage is still substantial.

Even though current apparatus using commutated eleett-omagnetic means is a sianificant immrovement, over zr-ior commutatorless ones, the problerms of- low control bandwidth and inte---,'-eromete- inter-ference persist. In such an ancaratus, a substace is moved magnetically in one lilnealdirection and the commutated electromagnetic means mounted on the substage in turn moves the stage in the normal direction. The sub-stage is heavy because it carries the magnet tracks to move the stage. Moreoverl heat d-ss'Lnat-on on the stage compromises accuracy.

It is also well known to move a movable me-11-'-er (stage) lin one long linear direction (e.g. more than 10 cm.) b",,r usinc: two o' -he lnear motors in parallel where coil L L- and mac:-ne-. are co-mbined. T _n this case, the stage is guided bv some sor of a linear guiding member and driven r- One ectiOn Dy a linear motor installed narallel to ear dir the quidina merLDer. When driving the stage only O the extent of extremely small based on the cc-mbination stroke, the guidless structure of several electromagnetic actuators, as disclosed in the prior art me-ntioned before, can be adopted. However, in order to move the guideless stage to a long distance in one linear direction, a specially structured electromagnetic actuator as in the r)r- ior arts becomes necessary, causing the size of the a.,:maratus to become larcer, and as a result, generating a nroblem of consuminc more electricity.

io it is an object of the present invention to make it iDossible for a Tuidless stage to move in the dIrection o.L a long linear motion, using electromagnetic force, and to provide a light weigh.t. apparatus in w. hich low inertia and. hich resnonse are achieved.

Furl--her-,-,o--e, it is an object of the present invention to nrovide a waidless stage apparatus using cormmercially available regular li-nearmotors as c actuators for one linear dLrection motion.

Furthermore, It is an object c:E the present inventon to provide a 9Llideless stage apparatus capable of active and precise position control for small disnlacements without any contact in the direction orthoconal to --he long -inear motion direction.

-:'urt he it is an obect of the present invention to nrovilde a completely non-contact s-aw-e annaratus by -orovidnc a movable member (sace body, to move in cne ljnear d-i----ct-on and the second movable member to move sea-ientially in the same direction, cc-nstan-ly keepinz a cer:a-n sDace in between, and---providing the eleciromac-iet-c force (action and reaction force) -.:;n the direction 4 orthogonal to the linear direction between this second movable member and the stage body.

Furthermore, it is an object of the present invention to provide a noncontact stage apparatus capable of preventing the positioning and running accuracy from deteriorating by chang.J_ng tension of various cables and tubes to be connected to the noncontact stage body which moves as it supports an object.

Furthermore, it is an object of the present invention to crovide: a non-contact apparatus which is short in its height, by arranging the first movable member and the second movable member in parallel which move in the opposite linear direction to one another.

Furthermore, it is an object of the present invention to provide an apparatus which is structured so as not to change the location of the centre of the gravity of the entire apparatus even when the non-contact stage body mo-f,-es in one linear direction.

According to one aspect of the present invention there is provided a stage apparatus having a movable stage which is movably supported on a base, comprising, a drive device for driving said movable stage, a balancing portion disposed outside said movable stage, and a non- contact bearing which opposes said balancing portion to said base without contact therebetween, wherebv said balancing portion moves in response to a movement of said movable stage, with a movement component in the direction oiDiDosi--e to the dilrection of move-nent of said movable stage without any mechanical contact with said base.

As a specific feature of the invention linear commutated motors can be located on opposite sides of the stage and each commutated motor includes a coil member and a magnetic member one of which is mounted on one of the opposed sides of the stage and the other or which is mounted on the drivinQ frame. Both motors drive in the same direction. By driving the motors slightly different amounts small yaw rotation of the stage is produced.

in accordance with another aspect of the present invention there is provided a stage driving method for driving a movable stage which is movably supported on a base, comprising, opposing a balancing portion disposed outside said movable stage to said base without contact therebetween by means of a non-contact bearing, and moving, in response to a movement of said movable stage, said balancing portion with a movement component in a direction opposite to the direction of movement of said movable stage without anv mechanical contact with said base- -G- By restricting the stage motion to the three specified degrees of freedom, the apparatus is simple. BY using electromagnetic components that are commercially available, the apparatus design is easily adaptable to changes in the size of the stage. This high accuracy positioning aDoaratus is ideally suited for use as a reticle scanner in a scanning exposure system by pro-,,,--"d.Jng smooth and -orecise scanning motion in one linear direction and ensuring accurate alignment by controllilng small dis-olacement motion oer-Qe.-id-cula-- to the sca.-i-,-nc direction and small yaw rotation in the plane.

- Other aszects and features and advantages of' the present invention will become more apparent upon a perusal of -the followinS specification taken in conjunction with the accompanying drawings -wherein similar characters of reference indicate similar elements in each of the several views, Pand in which.

io is Fig. 1 is a schematic perspective view of apparatlus in accordance with the present invention.

Fig. 2 is a top plan view of the apparatus shown in Fic. 1.

Fig. 3 is an end elevational view of the structure show-i in Fig. 2 taken along line 3-31 in the direction of the arrows.

Fia. 4A is an enlarged -perspective, partially ex,Dioded, view showing the carrier/follower structure of Fig. i and exploded from the positioning guide.

F-J-9. -'5-is an enlarged horizontal sectional view of a portion of the structure shown in Fig. 5 taken along line 4B in the direction of the arrow.

Fig. 4C is an enla rged elevational sectional vie,,.; of a portion of the structure shown in Fig. 2 taken along line,1C in the direction of the arrow but w-;-,',-1 the voice co- motor removed.

Fig. 5 is an elevational view o a portion of the structure shown in Fig, 2 taken along line 5-5' in the direction of the arrows.

Fia. 6 is a block diagram schernatically illustrating the sensing and control systems for controlling the ition of the stace.

-Dos L - - L- Fig. 7 is a plane view, similar to Fig. 2, llustrat-ing the preferred embodiment of the present invention.

Fig. 8 is an elevational secti, onal vie-,,: of the structure shown in Fic. 7 taken along line 8-8' in the direction of the arrows.

Pigs. 9 and 10 are much schematic views similar to Fig-s. 7 and 8 and illustrating st-J11 another embodiment of the present invention.

i c is While the Drese--i invention has annlicab-il.-L:ty Gene-a21y to electroT.,acnetic alignment systems, the ureferred e-,ibod-.ment involves a scanning apparatus:Eor a reticle stage as illust-rat-ed in Figs. 1-6..

ReEerring now to the drawings, the Dosition-ing annarazius -10 o.E the present --JInvei-.,t:-Jcn. includes a base structure 12 above which a reticle stace 114 is susnended and moved as desired, a reticle stage nos;LtJon trackilnw laser interferometer system 15, a Position sensor!3 and position control system 16 or)erating from a CPU 16' (see 6) 17 Jt,cri elongate position-inS guide _is Mounted on the base 12, and support brackets 18 (two brackets in the is illustrated embodiment) are movably supported on the cuide 17 such as by air bearings 20. The sumnort brackets 18 are the connected to a drivina assembly 22 in-the form of a _z T-,-m=net-c track asserbly or dr_iv..i-na frame for driving reticle stace 14 in the X d-Lrection and small- yaw rotation.

The drivina frame includes a nair of -parallel spaced apart magnetic L-rack ar-ms 24 and 26 which are connected together to form an open rectangle by cross arms 28 and 30. T TI the pi-e--.':'erred embodiment the driving frame'22 is movably sunzorted on the base structure 12 such as by air bear-"1n-s 32 so that the frame is JEree to move on't-he base structure -Ln a direction aligned with the longitudinal axis of 17, the -Drincinal direction in which the scanning mo-on olc the reticle stage is desilred.

As used herein lone or a Ilfirst direection,' appi-Jes to movement of t- a m e 2 2 o r t he r e t --" c 1 e s t a z e I e. e i th e r -,; o rw a r d c r back in the X direct-Lon along a line aligned the lonc:t:ud-nal axis of- the cyu-ide 17.

Referri na now to Figs. 1 and 5 to exDla-Jn further in detail, the elongate guiding member 17 in the X direction has front and rear cu-id:ing surfaces 17-k and 17B which are almost iDer-,Dendicular to the surface i2A of the base str-ucture 12. The front guiding surface 17A is against the rectangular driving frame 22 and g-ulides the air bearing 20 wh.-Lch is fixed to the inner side of the suiDDort bracket 18. A support bracket 1-8 is mounted on. each end ofS the upper surface of: the arm 24 which is parallel to the guiding member 17 of the driving frame 22Furthermore, each surr)ort bracket 18 is formed in a hook shaDe so as to st-raddle the a- uiding member 17 in the Y direction and with the free end against the rear auiding surface 175 of the rear side of the guiding member 17. The air bearing 20' js fixed inside the free end of the s-ur):ort brackets 18 and against the rear guiding surface 172. Therefore, each of the support brackets 18 is constrained in its disiDlacement in the Y direction by the guiding member 17 and air bearings 20 and 201 and is able to mov e only in the X direction.

Now, according to this first embodiment of the present invenzilon, the ai r bearings 32, which are fixed to the bottom surfaces of the 'Lour rectangular narts of the driving frame 22, make an air layer leaving a constant wap (1 several gm) between the pad surface and the surface 12A of the base structure 12. The driving -f--a-,ne Js buoyed up from the surface 12-1, and supported perpendicularly Z d-:_-ect-Jon) by the air layer. it will be exn-'la-ned in detail- later, b-.-,t in Fig. i, the 60 S'nown iDos-t--oned above the upper p-art of the elongate arm 24 is Dositioned laterally in the Y direction by air bear---nas 66A and 663 sunoorted by a bracket 62 ac:a--,nst op-posite surfaces 17A and!75 cf.' guiding member -17 and vertically in the Z i 0 is -10 direction by air bearings 66 above the surface 12A 0 - the base structure 12. Thus, the carrier/follower 60 is 1Dos-it..Loned so as not to contact any part o-E the driving frame 22. ','cco--dingly, the dr--'1v--'-nci frame 22 moves only in one linear X direction, guided above the base surfac2 12A and laterally by the guiding member 17.

Referring now to both Fig. 1 and Pig. 2, the structure the ret-Lcle stace!4 and the drilving frame 22 w be exnla-ined. The reticle stage 14 includes a main bod-,/ 42 on which the reticle 44 is nositioned above an opening 46. The reticle body 42 includes a pair of opposed sides 42A and 429 and is positioned or suspended above the base structure 12 such as by air bearings 48. A plurality interferometer mirrors 50 are Drovided on the main body 42 o-E the reticle stage 1,- for operatJon with -he laser interferometer position sensing system 15 (see Fig. 6) for deter-mining the exact position of the reticle stage which ed to the iDosit-on control system!6 in order to drect a-nro-or-ate drive sianals for mov-g the ret-cle stage as desired.

Pr-J-mary movement of the reticle stage acccmnlished with first electromagnet ic drive assembly or means in the form of senarate drive assemblies 52A and 52B on each oJE: theopposed sides 42A and 42B, respectively The d,r:-ve assemblies 52A and 52B include drive coils 54A and -.":'->,-edly mounted on the reticle stage 14- at t 42A and 422, resDect. A-vely, fEor coor)eratJnc with mawnet traCks SCA and 56D on the mawnet track arnis 2,i and 26, resnectively, of' the dri've -Erame 22. While -in- the embodiment oi: the invention t_he m-acnet ccis are mounted on the reticle s--ac-:e and the magnets are mounted on the drive frame 22, the positions of these elements o'':; the drive assembly 52 could be reversed.

Here, the structure of the reticle stace 14 will be exDla-ned in detail. As shcwn in Fig. i, the stace body 42 is installed so that it is 'Eree to move in the y direCtion-in. the rectang-ular s-,)a'ce L..Side the drivina 22. The air bearing 48 fixed under each of' the four corners of the stage body 42 makes an extremely small San between the Dad su--.-'-ace and the base surlface 12A, and buoys up and supports the entire stace i, ---':rom the surface i2A. These air bea_rings 48 should Dre-Eerablv be ure-loaded types with a recess:.:or vacuum attract-Jon to the surface As shown in Fic. 2, a rectangle open-ing 46 in the center o"OL the stage body 42 is provided so that, the urojected image of the pattern formed on the reticle 44 can is go through. In order 'Loz- the projected image via the rectangle opening 46 to pass through the projection optical system PL (See Fig. 5) which is installed below the rectangle opening, there is another en.enins 123 nrovided at the center mart c"-- the base structure 12.

The reticle 4, 2 0, - -'s loaded on the ton surface of: the stage body by clampinc:

members 42C which are protrusively pl, aced at four around the rectangle opening 46, and clamped by the vacuum, pressure.

-the interferometer mirror SOY, which is fixed near the side 423 of' the stage body 2 near th.e arm 25, has a vertical elongate relE-iect--lng suri.E-:ace in the X direction which leng--'r.. is somehwat longer than the mo-jable stro',,:e of the stage 14 in the X direction-, and the laser beam LEy from the -nter-'eromete--?- is incident perpendicularly 3 0 on the --e'lectJnci in 1-Pig. 2, the laser beam, LEY angle by the mirror i2D which is 'fixed on the side off thle base structure 12.

Referring now '.--o Fig. 3 as a partial cross -sect il onal draw4na of the 3-31 view in Fig. 2, the laser beam LBY which is incident on the reflecting surface oJE' the interferometer mirror SOY is placed so as to be on the same iD!ane as the bottom sur-race (the surface where the oattern C is formed) of the reticle 44 which is mounted on the clampIng memnber 42C.

Furthermore, in 3, the air bearing 20 on the end side c-..L: the sunnort brackets 18 acainst the c7u.Ld-J--c surface 17E of the member 17 is al, so shown..

Referring once again to Figs. 1 and 2, the laser beam LBX1 from the Xl-axis interferometer is incident and reflect'e_d on _te interferometer mirror 5OXI, and the laser is beam L5X2 from the X2axis -interferometer is incident- and reflected on the -interferometer mirror 5OX2. These two mirrors SOXI and 5OX2 are structured as corner tube ty', pe mirrors, and even when the stage 14 is in yaw rotation, they always maintain the incident axis and re--1lect-in5 axis of -the laser beams parallel within the XY Plane.

Furthe=cre, the block 12C in Fig. 2 is an oo-.-ical block such as a prism to orient the laser beams LBX! and LBX2 to each of the mirrors 5OX1 and 5OX2, and is 'fixed to a part of the base structure 12. The corresponding block for the L5y laser beam is not shown.

Tn Fig. 2, the distance BL in the Y direction between each of the center lines c-"-' the two laser L2X2 is the lenath of the base line used amount o-LE yaw rotation. Accordingly, the dit-terence between the measured value LX! beams LBX! and --c calculate -the value of the i n z-e X ll, dilrection of the Xiaxis interferometer and the measured value tX2 in the X direCtion of the X2-axis int-erferomeer divided bv the base line --,enc:--h BL _Js the annroximate amount o..: vaw rotation in an extremely small ranwe. Also, -13 -, 0 is half the value of the sum of the AX1 and 6X2 represents the X coordinate position of the entire stage 1,C. These calculations are done on the high speed digital processor in the position control system 16 shown in Fig. 6.

Furthermore, the center lines of each of the laser beams LEX1 and LBX2 are set on the same surface where the pattern is '--o---Tned on the retl cle Z14. The extension of the line GX, which is show-n in Fila- 2 and dilvides in haltE the siDace between each of: the center lines of laser beams LEXI and LBX2, and the extension of the laser beam LBY intersect within the same sur-face where the patter-n is formed. And.furthermore, the optical axis AX (See Fias. 1 and 5) als6 crosses at this intersection as shown in Fig. 1. in Fig 1, a slit shane illumination field ILS which includes the optical axis AX is show-n over the reticle 44, and the mattern image of the reticle 44 is scanned and exIDosed onto the -jhoto- sens..t-ive substrate via the z)rojection o-itical svsten, PL.

Furthermore, there are two rectangular blocks 90A and 909 fixed on the side 42A of' the stage body 2 in Figs. 1 and 2. These blocks 90A and 903 are to receive the driving force in the Y direCtion from the second electro-magnetic acuator 70 which I's mounted on the carriLe--/.::oi lower 60. Details will be exolained later.

The drivi, ng coils 54A and Sj:-IS which are f ixed on the boi-i sides o"" the stage body 42 are form.ed flat parallel to the XY Diane, and pass through the mawnetic space in the slot which extends in the X d-i--ect-ion of the macrl-,et-Jc track 5GA and 56B wilthout any contact. The assembly o"f the coil 5,i and the magnetic track 55 used in the uresent embodiment is a commercially easJly accessible Inear motor for general purposes, and it couid be e-Jt.---with or without a commutator.

Here, considering the actual design, the moving st:roke of the reticle stage!,! is mostly determined by the size of the reticle 4 (the amount o-f- movement required at the time OJE sca-,-ning.-,ror expos-ure and the amount of movement needed at the -Lime of removal of the reticle from the optical system to chancre the rel-icl-p-). 7_ n th -- case of the rrese-it embodiment, when a 6-inc-n (15.24 cm) r.et.icle isused, the mov,-ilng szroke is about 30 Cm.

7, fore, the drvna frame 22 and the As mentioned be-- - - L stage!4 are -independently buoyed up and sup-ported on the base surface 12A, 'and at the same time, maSnet--, c action and reaction force-is applied to one another in the X direction only by the linear motor 52. Enecause of that, the law of the conser-ja-L- on of momentum is seen between the drJvnz is f tage 22 and the sk- Now, suppose the weight of the entire reticle st-ac-:e 14 is about one fifth of the entire weight of the frame 22 which ncludes the sunnort braCkets 18 - J_ then the forward movement of 3 0 cm, of the stace 14 1 n the X direct ion makes t'-_ driving frame 22 move by 6 cm backwards in X d. ire -- t i o n. This means that the location c.'-' the center of the gravity c.-'^ the apparatus on the base structure 12 is essentially flixed in the X d-Lrection.

In the Y direction, The--e-,:ore, the there is no movement of any heavy object.

chanae in the location- of the ce-nter of L-he gravity i-. t-le Y direction is also relatively s:ace 14 can be moved in the X direction as described above, but the movinc: coils (54A, 545) and the stators (56h., SCS) of the linear motors 52 will each oher (coililde) in the Y direction w--" thout an X d i -- -- c t il on a c t u a t c r.

There-':ore, the 60 and the second electromagnetic acti-,-ator 7o, wh-tcr. are the -is- characteristic component-s of the present invel-tion, are -Drovided to control the stace 14 -Ln the Y direct--,on.

Referring now to Fics. 1, 2, 3, and 5, the structures of them will be explained here.

7s shown _n Fig. 1, the carrier/follower 60 is movably installed in the Y direct- -Lion via the hook like suDDort bracket 62 which straddles over the Tu-idLnc me-,,be-- 17. Furthe--tno--e as evident from Fig. 2, the carr-er/fo-',-'owe.-t- 60 is placed above the ar-m 24, so as to maintain a certain siDace between the stage 14 (the body C2) and to the arm 24, respectively. One end 60E of' the carr.i..er-/f ol lower 60, is substantially protruding in-ward (toward the stage body 42) over the arm 24. Inside this end part 60E is fixed a driving coil- 68 (same shape as the D coil 54) which enters a slot space czE the magnetic track SA.

Furthermore, th-e bracket 62 sup-ported; a-'L- bear-Ina- 66-t (See _Frias. 2, 3, A and 5) against the. guiding sur-face 17A of the cudina mennuber 17 is L":ixed in th,e s:)ace between the meruber 17 of the carrier/ f oll ower 60 and the arm 2,. The air bearin 66 to buoy un an-d the carrier/follower 60 on the base s,-,r-L.:ace!2.C-,'- is also shown The air bearing 665 against the u-Jdng surf-ace 1-75 J:

of the c-uidns me-..ber 1-7 is also fixed to t---he free end 0..

suDDort bracket 62 on the other side of th- hook fErom air bearing 661, wth meT,,ber!7 therebeween.

-- t". - - Now, as evident -L"rom Fic. 5, the carr-er/.jollowe-- 60 - n both the magnezic track 567.. and L-he stage body 42 in the Y and Z d-----cLJons, respectively. Sho,N-- projection oDtical systern PL and j L Co-ur-,. rod CS to support the base structure 1-2 above the projection on---Jcal sysem PL. Such an arrangement is typical for a projection aligner, and unnecessary shift o--E the center of the gravity O.E the structures above the base structure 12 would cause a lateral shift (mechanical distortion) between the column rod CS and the projection or)t-cal system PL, and thus result in a de.lect-.:lon o.E the image on the photosensitive substrate at the time oZE ex-posure. Fence, the merit o_ L-he device as in the nresent embodliment where the motion of the -- 0 stage 14 does not shi-ft the center of the gravity above the base structure 12 is substantial.

Furthermore referring now to Fig. 4A, the structure L - - of' the carrier/follower 60 will be explained. In Fig. i-A, the carrier/follower 60 is disassembled into two parts, 60A and 605, for L-he sake of facilitating one's understanding. As evident from Fig. 4A, the drivina coil 68 to move the carrier/follower 60 itself in the X direction is fixed at the lower part of the end 60E of the carrier/.Eol lower 60. Furthermore, the air bearing 66C is placed against: the base structure 12A on the bottom s-ar--ace o-- the en.d 60E and helps to buoy up the carr-i----/- ::ollowe-- 60.

Eence the carrier/follower 60 is supDorted in the Z direction with the following three po-Lnts, the two air bearings 66 and one air bearing 66C, and is constrained in the Y direction for movement in the X direction by air bearinas 66.A and 659. What is inDortart in. this structure is that the second elec----omag--netic actuator 70 is arranced back to back with the sunnort bracket 62 so that when t_--actuator generates the drivina force in the Y reaction forces in the Y direction betwee-n the sta-ge!4_ andcarr i e r/_f ol lower 70 actilvely act upon the air bearincs 65.A and 66B which are fixed inside the support b--acket 62. in other words, a--ranc-Jng the actuator 70 and the air bearincs; 66A, 69B on the line narallei to the yav--:s in the XY nlane hel-os Drevent generating unwanted stress, which mJ1.9ht deform the carrier/ f ol lower 60 mechanically when the actuator 701 is in- ope- ration. Conversely, it means that it is possible to reduce the weight of the carrier/follower60.

As evident from F-Las. 2, 4A and 41C described above, the magnetic track SGA in the arm 2, of the driving frame 22 provides magnezic flux -for the driving coil 54A on the stage body 42 side, and concurrently 1Drovides magnetic flux the carrier/follower 60. AS -or the driving coi 68 for for L-he air bearings 66A, 669 and 66C, a vacuum pre-loaded type is. preferable, since the carrier/followe_r 60 is lic:),',-t. Besides the vacuum pre-loaded type, a magnetic pre-loaded type is also acceptable.

Next with reference to Figs. 3 15 and 5, the second is actuator mounted on the carrier/f ol lower 60 will be e=lained. A second electromagnetic drive assembly in the form o' a voice co l motor 70 is made up of a voice coil 74 attached to the main body 42 of the re. ticle stage 14 and a maSTnet 72 attached to the carrier/follower 60 to move the stage 14 for small d-:1-sr)lacernen-"s in the Y direction in the plane of the travel of the stage 1, orthogonal to the X direction long linear motion produced by the driving assembly 22. The iDositions of the coil 74 and magnet 72 could be reversed. A schematic structure of the voice ccil motor (VCM1) 70 is as shown in Figs. 3 and- 5, and the detailed structure is shown in Fig. 45. show- in Fig. 5.s a cross-sect-onal ve,,4 of the VCM 70 sectioned at the hor.-:Lzontal plane shown with an arro.,.., 43 in In Fig_.

45, the magnets 72 of the VCM 70 are fixed onto the carr.:

-Ler/-Lcollower 60 side. And the coil o_f the VCM, 70 comprises the coilbody 74A and its suu-Dorring part 7,IB, and the sur)portng part 745 is fixed to a connecting plate _i8_ 92 (a plate vertical to the XY plane) which is riaidly laid across the two rectangular blocks 90A and 90B. A center line KX of the VCM 70 shows the direction of the driving force of the coil 74, and when an electric current flows through the coil- body 74A, the coil 74 displaces into either positive- or negative movement in the Y direction in accordance with the direction o-f the current, and generates a force corresnondent to the amount o--,": the current. Normally, in a commonly used VCM, a ring-like damper or io bellows are provided between the coil and magnet so as to keep the gan between thecoil- and magnet, but according to the present enibodiment, that gap is kept by a follow-up motion of the carrier/f ol lower 60, and there-fo-re, such supporting elements as a da-,nner or bellows are not necessary.

In the present embodiment, ca-oacitance wap sensors 13A and 13B are provided as a positioning sensor 13 (see Fig. 6) as shown in Fig. 4B. In Fig..4B, electrodes for to detect th.e chancie is in the can in the X direction between the side surface off the rectangular blocks 90A and 903 facing with each other n the X direction and the s.:'_de surface o. a case 70' of the VCM 70. Such a 'Dositioning sensor 13 can be -placed anywhere as far as it can detect the gap change in. the Y d-'.--ect-on between the carri er/i.Eol lower 60 and the stage 14 xor the body 42). Furt.-.erm--re, the type of the sensor be anv of a noncontact type such as nhotoelec!---r-'-c, nductive, ultrasonic, o_r air- micro system. The case 701 in Fic.

fo-med with the -o.wer 60 in one, and nlaced (sna::-a-;",i) carrier/fol not to contact any member on the reticle stage for the wan between the case 70' and the rectancul 90A and 901 in L-he X direction (scannincr dir-ection) so as side. A'S ar blocks 1 when -,o -'s :3 0 the gap on the sensor 13A side becomes wider, the gap on the sensor 13 B side becomes smaller. Therefore, if the di.l'-'-4-erence between the measured can value by the sensor -13A and the measured Sap value by the sensor 13B is obtained by either dicital operation or analog operation, and a direct servo (feedback) control svstem which controls the driving current o-f the driving co-5-1 68 --L'or the carrier/fol lower 60 is desianed using a servo driving circuit which makes the gap difference zero, then the car_rier/follower 60 will automatically perform a follow- up movement in the X direction always keening a certain space to the stage body 42. Or, it is also possible to design an indirect servo' controI-system which controls an electric current flow to the driving coil 68, with the operation of nosition control system 16 in Fig. 6 using the measured gap value obtained only from one of the sensors and the X coordinate Position of the stage 14 measured from the X axis interferometer, without using the two ca-o sensors 13A an,. 133 In the VCM 70 as described in F.Lg. B, the gap between the coil body 74A and the magnet. 72 in the X direction (non-energizing direction) is in actuality about 2 - 3 mm. There-Eore, a follow-up accuracy of the carrler/follower 60 with resmect to the stawe body 42 would be acCeiDtable a-t around .5 1 mm. This accurac-,,, depends on how much o_f the yaw rotation. of the stace bodv is allowed, and also depends on the length of the line in the KX dilrection (energizing dlirection) of the coil body 74.P. of the VCP1 70. Furthermore, the degree of the accuracy -for this can be- substantially lower than the rrecise 1DOS-it.'Loning accuracy for the stage body 12 using an interferometer (e.c-r., 0.03 gm supposing -esoiut-ion of the -inte--'Le--o-,n.eter is 0.ol pm.) This means t:hat the servo 20- system for a 1011ower can be des-Icned arly simPly, and the amount of - L ower control system L cost to install the foil would be small.

rurthermcre, the line KX in Fig 4E is so as to go through the center of the gravity of the entire stage -14- on the XY plane, and each of centers of the pair o_f the air bearing 66A and 66--P Provided inside the sur)-Dort:

brackets 62 show---n in Fic U 11 in the XY plane.

also Positioned on the line Show----- in Ficr.

L_ 41- is a cross-sectional drawing of the part whch includes the c-udzng member 17, -he L CarrierL follower 60, and the magnetic track56A sectJoned from the direction 0= t the arrow 4C in Fig. 2. The arm 24 storing-the ma-!netic track s6 _k is buoyed up and suID-Ported on the base surface 12A by the air bearing 32, and the carrier/j,-:ollower 60 s buoyed ur) and suPDorted on the base surface 12A by the air bearing 66. At. this time, the height of the air bea-ina 48 at h stace bod A-) ( e bottom surface o. the y see F I-s 3 _ or and t--ie height o= t, he air bearing 32 are determined so as to Diace the dr-,i,-i, coi 5'A c-n the stage body -2 side '-zeez)Jng a 2 - 3 mm ga-D in Z direction in the slot space c= L the magnetic track ssA-- Each of the spaces between the carrier/fo-,ower 60 and the arm 24 in the Z and Y directions hardly chancres because the-Y are both guided by the common c:uid-;,---ig member 17 and the base surface 12A. Furthe-1-,-,iore, even _if there is a difference in the height in the Z d4 part on. the base between the .e air lbearincr 32 at where tn tbottor,, --,,r-inc frame 22 (arm 24) is s,,.ir=ace o- the di- g-u'.,-ed and L-he r)a th.e base surface Eace Of 'ne stac7e body is the bottom surf, J_ L guided, as ionc as -he d--- w i n th e m ov -j n 12A where the 9 stroke, t,-n -- -is mrecis;=!y cons-an!-- between the magnetic track 56A and the driving coil 54A is also preser---ved constant.

Further-more, since the driving coil 68 for the carrier/fol lower 60 is originally fixed to the is carrier/followe_r 60, it is arranced, maintaining a certain aap c-LP 2 - 3 mm above and below -In the slot space of the nagnetic track 5GA. And the driving coil 68 hardly shiLots in the Y drec-ion wth resiDect to -he magnetic track 56A.

Cables 82 (see F-59. 2) are provided for directing the Signals to the dri've coils 5,-A and 542 on stage 14, the voice coil motor coil- 74 and the carrier/follower drive coil 68, and these cables 82 are mounted on the carrie--/follow--er 60 and guide 17 thereby eliminating drag on the reticle stage 14. The voice coil motor 70 acts as a buffer by denying transmission of external mechanical disturbances to the stawe 14.

ThereJEore, referring now to Figs. 2 and 4A, the cable issues will be described further in detail. As shown in Fig. 2, a connector 80 which connects wIres of the electric s7s--em and tubes of the air pressure and the vacuum system (hereinafter called,cables") is mounted on the base structure 12 on one end of: the guiding member 17. The connector 80 connects a cable 81 from the external control system (including the control system of' air pressure and vacuum system besides the electric system control System shown in Pia. 6) to a flexible cable 82. The cable 82 is connected to the end part 60E. of th-e carrier/follower 60, and electric systerm wires and the air Pressure and the vacuum system tubes necessary for the s-ace body 42 are d-Istributed as the cable 83.

As mentioned be-fore, the VCM 70 works to can-cell a cable,s drag or an influence by tension, but sometimes its in-fluence apbears as mornient in unexpected direction be::.v,;een the carr ier/fol lower 60 and the stage body 42. In other words, the tension of the cable 82 gives the carrier/ follower 60 a force to rotate the guiding surface 0-f the guiding member 17 or the base surface 12A, and the tension of the cable 83 gives a force to the carrier/ zoo! lower 60 and the stace body to rotate relatively.

One c--" these moments, the constituent which shifts the ca--r-er/.-lol lower 60, is not problematic, but the one which shifts the stage body in X, Y, or e direction (yaw rotation direction) could affect the alignment or overlay accuracy. As for in X and 6 directions, shifts can be corrected by-a- consecutive drive by the two linear motors (54A, 56A, 545, 56E), and as f or in the Y direction, the shift can be corrected by the -VCM 70. -In the present embodiment, since the weight of- the entire stage 14 can be reduced substantially, the response of the motion of the stage 14 by VCM 70 in -the Y direction and the response by the linear motor in X and e directions will be extremely high in coo.oeration with the completely non-contact guidless structure. Furthermore, even when a micro vibration (micron order) is generated in the carrier/f ol lower 60 and it is transferred to the stage 14 via the cable 83, the vibration (from several Hz to tens of Hz) can be suf-..L-c-ently canceled by the above mentioned high response.

X.Tow, Fia. 4A shows how each of the cables is distributed at the carr-er/.Lollower go. Each of' the drivinc signals to the driving coil 54A, 54E for L-he stage bodY 42 and the driving coil 7,I o_f the VCM 70 and the detection sanal from the position sens.or!3 (the gap sensors 13B) go through the electric system wire 82A f- r 07 1 t ' ne connector 80. The pressure gas and the vacuum, to each of the air bearings 8 and 66 go through the pneumatic 1 23 system tube 821 from the connector 80. OP the driving signal to the driving coil- 54-A through the electric system wire 831k wh - ch the stage body 42, and the pressurized gas bearing 48 and the vacuum for the cla-,rt-Ding through the pneumatic system hoses 835.

Furthermore, it is nreferable to have a separate line the -oneumatc svsteT,. 'or the air bea-y--'n,-js 20, 201 and 32 of the driving 22, the other hand, and 545 goes is connected to for the air member 42C go n 0 is 2.5 3 D indenenderit of' the one shOwn in 2. Also, as s".n-cw-- in Fig. 4A, in case -the tension or vibration of the cable 83 cannot be prevented, it is advisable to arrange the cable 83 so as to limit. the moment by -L-he-ension or vibration the stage body 42 receives only to Y direction as much as possible. -In that case, the moment can be canceled only by the VCM, 70 with the highest response.

Re-ferrina now to Figs. 1, 2 and 6, the nosition-ing of tne reticle stage 14 is a--comi)lished f.'-st knowing -,--s ex;st-;,--g positior ut-jliz---ig the laser interferomet-er system is. Drive siwnals are sent to the rericle stage drive coils 5,1A and 54B for driving the stage 14 in the X direction. A difference in the resulting drive to the onDosite sides 42A and 42B of the reticle stage 14 will produce small yaw rotation of the reticle stac-.-e 14. An annroDrial.e drive sianal to the voice coil 72 of vc)-C-e COil motor 710 produces small displacements o:E th-e reticle stage - -1 -ection. J1-s the iDosi-on of the reticle 'I - - the Y di- k_ - s7-ac-e 14 chances, a drive signal is sent to the ca--r.z coil 68 causing the ca-:-Jer/followe- 60 o -ollow the reticle stage I-- ar)r)14--d drive forces assembly or drive.:::rame the reticle 14. Resulting reaction forces to move -the maS.--,et-Jc traCk 22 -J-1 a direction- c-i-Dos-ite to the stage 14 to substantially maintain the center of gravity of the apparatus. It. will be anDreciated that the counterweigh- or reaction movement of the magnetic track assembly 22 need not be included in the apparatus in which case the magnetic track assembly 22 could be fixedly mounted on the base 12.

As described above, in order to control the stage system according to the present embodiment-, a control system as shown in Fig. 6 is installed. This control svstem in Fig. 6 will be further eDmla-ined in detail here. X! drivina coil and X2 driving coil composed as the driving coils 54A and 545 of two linear motors respectively, and Y driving coil composed as the driving coil 72 of the VCM '70 are ulacedin the reticle stage 14, and the driving coil- 68 is niaced in the carr-er/--,ollowe-- 60. Each of these driving coils is driven in res-,->onse to the drivina sianals SXI, SX2, SY1, and S4X, respectively, from the nosition control system 16. The laser interferometer system wInich measures the coordinates nosition of' the stage 14- comprises the Y axis interferometer which sends/receives the beam LEv-, the X1 axis interfel-ometer which sends/rece-ives the beam LSXI, and the X2 axis interferometer which sends/receives the beam LBX2, and they send position information for each of the directions of the axes, iFY,!FX1, IFX2 to the position control svstem 16. The position control system 16 sends two driving signals SXT and 5X2 to the driving coils 54A and 54B so that the difference between the Dosition information!FXI and IFX2 in the X direction will become a r)reset value, or in other words, the yaw rotation of the reticle stace!4 is maintained at the speci-fied amount. Thus, the yaw rotation (in e di-rection) positioning by the beams LBX1 and LBX2, X1 axis and X2 axis interferometers, the position control syste:n 19, and the driving signals 5Xl and 5X2 is constantly being -25 conducted, once the reticle 44 is aligned on the stage body 42, needless to mention the time of. the exposure.

Furthermore, the control system 16, which obtained the current coordinates i)osi---ion of the stage 14 in the X direction from L-he average of the sum of position in,,":orT-,,ation!FX1 and I.FX2 in the X direction, sends the drivina sanals SXI, SX2 to the d.riv-.;,.ng co--3-s 54A and 543, res.)ective"-,y, based on the various commands from the Host CPU 16' and the information CD for the narameters. Esoecially when scanning exposure is in motion, it is necessary to move the stage 14 straight in the X direction while correcting the yaw rotation, and the control system 16 controls the two drivincr coils 54A and 5,B to give the same or slightly different forces as needed.

Furthermore, the position i-nf-oi-,-tiatio,--. IFY.0Lrorr, the Y axis interferometer is also sent to the control system 16, and the control system 16 sends an ontimum driving signal SAX to the driving coil 68 of' the carr-ie--/.,c'ol- lower 60. At that time, t ' ne control system 1-6 receives the detection sc:nal S A from the position sensor 1:3 wmJc':i measures the snace between the reticle stage i,,'= and the carrier/1.001.10wer 60 in the X direction, and sends a necessary signal SAX to make the signal S P. into the preset value As mentioned before, the follow-up accuracy for the carr'Ler/f ol lower 60 is not so s-rJct that the detection signal 5 pe of the control system, 16 does not have to be evaluated strictly e--'ner. For examnlle, when controlling the motion by reading the nosition inflormation T7Y,!FXI, 7-7X2 every imsecond from each of' the --ter.L.'ero-,,ie--ers, the hi-ch speed nrocessor in the control s-istem 16 sa,,n,:Dles the curre-lt OfL the detection s--1c-:nal 5,, each time, determilnes whether the value is large or s-mall co,,.- c)ared to the reference value (acknowled( and i the -evjation surpasses e the d-i--e--tion), L i 5 a certain point, the signal SAX in proportion to the deviation can be sent to the driving coil 68. Furthermore as mentioned before, it is also acce)table to install a control system 95 which directly servo'controls the driving Coil 68, and directly controls the follow-up motion of the carrier/follower 60 without coing through the 1Dosition control system 16.

Since the mov-n5 stace system, as shown.has no attachment to constrain it in the X direction, small -influences may cause the system to drift toward the positive or negative X direction. This would cause certain parts to collide after this imbalance became excessive. The influences include cable forces, imprecise leveling o:E" the base reference surf-ace 12A. or friction between components. One s-mr)le method is to use weak bumpers (not shown) to prevent excessive travel of the drive asserriDly 22. Anothe-- simiDle method:is to turn off the air to one or more of the air bearings (32,20) used to guide the drive assembly 22 when the drive assembly -reaches close to the end of the stroke. The air bearing(s) can be turned or, when the drive begins to move back in the oD-,Dos-te direction.

More iDrecise methods recruire monitoring the position of. the drive assembly by a measuring means (not shoi.,-n.)l and applying a driving force to restore and maintain the correct nosition. The accuracy of.' the measuring means need not be precise, but on the order of' 0.1 to 1.0 mm. The drivinQ force can be obtained by using another linear motor (not s'now---r_) attached to the drive assembly 22, or another motor that is coupled to the drive assembly.

Final-ly, the one or more air bearings (66,66A,663) of' the carri er/ fol lower 60 can be turned off to act as a brake during idle periods of the stace 42. if' the coil 68 o:c the -'s carrier/f ol lower 60 is energized with the carr-J,-er/--E'ollowe.60 in the braked condition the dr.ve assembly will be driven and accelerated. Thus, the position control system 16 monitors the location of L-he drive assembly 22. When the drive assembly drifts out of positlon, the drive assembly is repositioned with sufficient accuracy by intermittently using the coil 68 of the carrier/follower 22.

in the first embodiment of the nresent invention., the driving frame 22 which functions as a counter weight is installed in order to prevent the center of the gravity 01: the entire system from shifting, and was made to move in' the opposite direction from -the stage body 42. However, wwhen the structures in Fias. 1 - 5 are applied to a system L_ where the shift off the center of the gravity is not a major problem, it is also acceptable to fix the driving frame 22 on the base structure 12 together. In that case, except for the problem regardiIng L-he center of the gravity, some o,f the effects and function can be ar)r)lied without making any chai.aes.

This invention provides a stage which can be used for high accuracy position and motion control in three degrees of -freedom in one plane: (I) long linear motion; (2) short linear motion perpendicular to the long linear motion.; and (3) small yaw rotation. The staae is isolated from mechanical disturbances of surrounding structures by utilizing electro-magnetic forces as the stage d---,ver. Bv urther usin( Zor this audeless stage, a high I a structure control bandwidt'n is attained. These two.1ac-ors conribute to achieve the s,,noot.n and accurate oDeration of: the staae.

Descrintion of the Preferred Embodiment 1.0 Searing in mind the description of the embodiment illustrated in Figs. 1- 6, the preferred embodiment of the r)resent invention is illustrated in Figs. 7 and 8 wherein the last two digits of the numbered elements are similar to the corresponding two digit numbered elements in Ficis. 1-5.

in Figs. 7 and 8, differing from the previous first eT,,bodimeri, the driving frame which -functions as a counter weicht is removed, and each o:E the magnet tracks 156-z, and 1569 of the two linear motors is rigidly mounted onto the base structure 11-2. The stage body 143 which moves straight in the X direction is placed between the two magnetic tracks 156A and 156B. As shown in Fig. 8, an opening 112B is formed in the base structure 112, and the stage body 142 is arranged so as to straddle the openling nart 1125 in the Y direc tion - There are four pre-loaded air bearings 148 fixed on the bottom surface at both ends of' the stacre body i42 in the Y direction, ana they buoy up and s=port the stage body 142 a=ainst the base surface 112A.

accordina to the -Dresent e-,,.Lbod-,nent, t,e reticle 14, is clamped and supported on the reticle chuck 1Diate 143 which is seMarately placed on the stace body 142. The straight mirror 150Y for the Y axis laser interferometer and two corner mirrors 150Xl, 15OX2 for the X axis laser interferometer are mounted on the reticle chuck -clate 143. The driv-;:. ng coils 1541A and 15,r1B are horizontally fixed at the both ends of the stage body 142 in the Y direction with resDect to the magnetic t--ac",5 156A and _15065, and due to the control subsystem nrevilously described, make the stage body 142 run straight in the X direction and yaw only to an extremely small amount.

As evident from Pig. 8, the magnetic track 1565 of the rc;ht side of the linear motor and -he r-,,a5Tnetc track L -29 -10 is 156A of the left side of the linear motor are arranged so as to have a difference in level in z direction between them. In other words, the bottom surface of the both ends in the direction of the long axis of the magnetic track 156 on the left side is, as shown in Fig. 7, elevated by a certain amount with a block member 155 az-aJnst the base surface 112A. And the carri er/f ol lower 160 where the VCM is fixed is arranged in the space below the elevated magnetic track i56A.

The carrier/f ol lower 1-60 is buoyed up and supported by the pre-loaded air bearings 166 (at 2 points) on the base surface 112A1 of the base structure 112 which is one level lbwer. "--:-5urthe rmore, two pre-loaded air bearings 164 against the vertical guiding surface 117A of the straight guiding member 117, whic h is mounted onto the base structure 112, are fixed on the side surface of the carrier follower i60. This carrier/follower 160 is d:-f-ferent from the one in Fig. 4A according to the previous embodiment, and the driving coil 168 (Fig. 7) for the carrier/.fL:ollower 160 is fixed horizontally to the mart which extends vertically from the bottom of the carrier/follower 160, and positioned in the magnetic flux slot of the magnetic track 156A without any contact. The carrier/ f ol lower 160 is arranged so as not to contact any mar,- of the mnagnetic track 156A within the range of the moving stroke, and has the VCM 170 which positions the stage body 1,2 precisely in the Y direction.

Furthermore, in Fia. 7, the air bearing 1-66 which buoys up and supports the carrier/fol lower 160 is provided under the VCm 170. The follow-up motion to the stage body 142 of the carrier/fol lower 160 is also done based on the detection signal fErom the position sensor 13 as jn the previous err-Dodimen-,.

In the second embodiment structured as above, there is an -inconvenience where the centel- of the gravity Of' the entire system shifts in accordance with the shift of the stage body 1,12 in the X direction, since -there is substantially no member which functions as a counter we i ah t. It is, however, nossible to position the stace body i42 precisely in the Y direction with non-contaCt electro-w,acne--.lc force by the VCM 170 by way of,-ollow--nc the stage body 142 without any contact using the carrier/f ol lower i60. Furthermore, since the two linear motors are arranSed with a dif-ference in the level in the Z direction between them, there is a merit where the sum or is the vectors of the force moment generated by each of the linear motors can be minimized at the center of the gravity of the entire reticle staae because the force moment ozE each of the linear motors substantially cancels with the or-her.

since an elonSated axis o..:' action (the line KX in- Fic. 43) c=L the VCm 1-70 is arranged so as to pass through th:e center of the aravity of -the entire structure of the stage not only on the XY plane but also in the Z direction, it is more difficult for the drivincr force of the VCM 170 to give unnecessary moment to the sta-ge body 142. Furthermore, since the method of connectinc; the cables 82, 83 via the carrier/follower 160 can be anplied in the same manner as in the first er--bodi-,nent, the L- J_ proble-n recardinw the cables in the completely non-contact guideless stacre is also imz)roved- The sarne m--,ideless Principle can be employed in another e-mbodiment For example, in schematic F-c:s. 9 and 10, the stage 242, su-pported on a bases 212, is driven lin the long X direction by a single movina coil 25, mov-inawithin a single magnetic track 256. The T-,,ag:iez:-JC track _Js i 0 3 0 rigidly attached to the base 212. The center OIEL the coil is located close to the center of gravity of the stage 242.

L - To move the stage in the Y direction, a Dair of VCM's (274A, 274B, 27 2A,272E) are energized to Drovide an acceleration in the Y direction. To control yaw, the coils 274A and 2745 are energized differentially under control of the electronics subsystem. The VCY magnets (272A,272B) are attached to a carrier/fol lower stage 260.

The carr4er/,ft:ollow--er stage is guided and driven like the -irst embodiment previously described.

This alternative embodiment can be utilized for a wa-fer st.age. Where it is utilized for a reticle stage the reticle can be positioned to one side of the coil 254 and track 256, and if desired to maintain the center cl' gravity of the stage 242 passing through the coil 254 and track 256, a compensating opening in the stage 242 can be nrovided on the onposite side of the coil 254 and track 256 fro-m the reticle.

Merizs gained -from each of the embodimenits can be roughly listed as follows. To preserve accuracy, the carrier/ f ol lower design eliminates the problem of cable drag for the stage since the cables connected to the stage follow the stage via the carrier/follower. Cables connecting the c arr ier/ fol lower to external devices will have a certain amount of drag, but the stage is free from such disturbances since there is no di-rect. connection to th.e carrier/-followe-- which acts as a buffer by denying the transmission of mechanical disturbances to the stage.

Furthermore, the count er - weight- descn preserves the location of the ce=er of gravity of the stage system during any stage motion in the long stroke direction by usino the conservation of momentum princiDle. 7, h. i S anparatus essenially eliminates any reaction forces is between the stage system and the base structure on which the stage system is mounted, thereby facilitating high acceleration while minimizing vibrational effects on the system.

In addition, because the stage is designed for limited motion in the three degrees oil freedom as described, the stage is substantially simpler than those which are designed for full range motions in all three degrees of freedom- Moreover, unlike a commutatorless apparatus, the instant invention uses electromagnetic components that are commercially available. Because this invention doe s not require custom-made electromagnetic comiDonents which become increasingly difficult to manufacture as the size and stroke of the stage increases, this invention is easily adaptable to changes in the size or stroke of the stage.

The embodiment with the single linear motor eliminates the second linear motor and. achieves yaw correction using two VCM,s.

W-hile the present invention has been described in terms of the nreferred embodiment, the invention can take many different forms and is only limited by the scope of the following claims.

33

Claims (24)

1. A microlithographic system which exposes a pattern of a mask onto an object, comprising:

an exposure device which exposes said pattern onto said object; stage; base structure which supports said stage in a manner in which said stage is movable; a first drive device which moves said stage in a first direction; ---abalancing portion which moves in a direction opp6site to the first direction of movement of said stage without holding either said mask nor said object; and a first non-contact bearing member connected to said stage to oppose said stage to said base structure without any contact therebetween, said balancing portion being heavier than the entire said stage including said non contact bearing.

2. A system according to Claim 1, further comprising: a second noncontact bearing member connected to said balancing portion to oppose said balancing portion to said base structure without any contact there between.

3. A system according to Claim 1 or 2, wherein said f irst drive device has a f irst portion to be connected to said stage and a second portion to be connected to said balancing portion.

4. A system according to Claim 3, wherein said f irst 34 portion and said second portion are not in contact with each other.

5. A system according to Claim 3 or 4, wherein said first portion comprises a coil member and said second portion comprises a magnet member.

6. A system according to Claim 3, 4 or 5, wherein the movements of said stage and said balancing portion follow the law of conservation of momentum.

7. ---Asystem according to Claim 1, 2, 3, 4, 5 or 6, wh(rein said first drive device comprises a linear motor.

8. A system according to any one of the preceding claims, further comprising a position detection device which detects a position of said stage.

9. A system according to Claim 8, wherein said position detection device comprises a reflective surface fixed to said stage.

10. A system according to Claim 9, wherein said reflective surface is a corner-cube type mirror.

SO

11. A system according to Claim 8, 9 or 10, wherein said position detection device detects a position of said stage with regard to said first direction during the movement of said stage.

12. A system according to Claim 8, 9 or 10, wherein said position detection device detects a position of said stage with regard to a direction which is different from said first direction during the movement of said stage.

z

13. A system according to Claim 8, 9, 10, 11 or 12, further comprising a control system which corrects yaw rotation of said stage based on a detection result by said position detection device.

14. A system according to Claim 13, wherein said control system is connected to said first drive device.

15. A system according to any one of the preceding claims, further comprising a second drive device which moves said stage in a second direction which is different from said first direction.

16. A system according to any one of the preceding claims, wherein said projection system projects the pattern optically.

17. A system according to any one of the preceding claims, wherein said balancing portion moves in such a way as to cancel a shift of the centre of aravity of said exposure apparatus.

o

18. A system according to any one of the preceding claims, wherein said balancing portion operates without a drive source.

19. A system according to any one of the preceding claims, 3M wherein said non-contact bearing is an air bearing.

20. A system according to any one of the preceding claims, wherein said stage comprises an opening though which said 5 exposure device exposes said pattern onto said object.

21. A system according to any one of the preceding claims, wherein said balancing portion is of a rectangular shape.

22. A system according to Claim 8, 9, 10, 11, 12, 13 or 14, wherein said position detection device comprises an interf erometer system.

23. A system according to any one of the preceding claims, wherein said exposure device exposes said pattern while said stage is moved in the f irst direction.

24. A system according to any one of the preceding claims, wherein said stage holds said mask.