GB2329520A

GB2329520A - Electromagnetic alignment and scanning apparatus

Info

Publication number: GB2329520A
Application number: GB9900935A
Authority: GB
Inventors: Akimitsu Ebihara; Thomas Novak
Original assignee: Nikon Corp
Current assignee: Nikon Corp
Priority date: 1994-06-27
Filing date: 1995-06-21
Publication date: 1999-03-24
Anticipated expiration: 2015-06-21
Also published as: HK1035431A1; KR100281860B1; JP3804787B2; GB9512659D0; HK1026767A1; HK1017824A1; GB9817493D0; GB2325564B; GB2325566B; GB9825844D0; GB2325564A; KR100281857B1; JP4687911B2; GB2325563B; HK1035432A1; GB2325565B; JPH0863231A; GB2329519A; JP2007242034A; JP2006258817A

Abstract

A scanning type exposure apparatus which exposes a pattern 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. A laser interferometry system LBX1, LBX2, LBY, 50X1, 50X2, 50Y detects the exact position and orientation of the stage. 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. A carrier/follower 60 holding a single voice coil motor 70 is controlled to follow the stage in the linear motion direction. The carrier/follower provides an electromagnetic force to move the stage small displacements in a direction perpendicular to the long linear direction, in order to ensure proper alignment.

Description

2329520 ELECTROMAGNETIC ALIGNMENT AND SCATNING APPARATUS The cresent

invention relates to a movable stage apparatus capable of precise movement, and particularly relates to a stale apparatus movable in one linear direction capable of high accuracy positioning and high sneed movement, which can be especially favorably utilized irr a microlitl25raphic system.

io in wafer steppers,' the alignment of an exposure field to the reticle being imaged affects the success of the circuit of that field.

in a scanning exposure system, the reticle and wafer are moved simultaneously and scanned across one another during the exposure seluence. This invention discloses an apparatus to achieve precise scanning motion for such a system.

To attain high accuracy, the stage should be isolated from mechanical disturbances.

This is achieved by employing electromagnetic forces to position and move the stage. it should also have high control bandwidth, which requires that the stage be a light, structure with no moving parts. Furthermore, the stage should be free from excessive heat generation which might cause interferometer interference or mechanical changes that compromises alignment accuracy.

Commutatorless electromagnetic alignment apparatuses such as the ones disclosed in U.S. Pat. Nos. 4,506,204, i,506,205 and 4,507,597 are not feasible because they is require the manufacture of large i-ra5net and coil asser-,,b.-',J-'-es that are not cotT,-,.ercaliv available. The -weJcht O' the stace and the heat generated also render these designs inappropriate for h--'ST'M accuracy applications.

An imnrovement over these commutatoriess apparatuses was disclosed in U.S. Pat. No. 4,952,858, which employs a conventional XY mechanically guided sub-stage to provide the large displace-ment notion in the -olane, thereby elim-inatina the need ifor large magnet and coill asse-mblies. The electromaanetic means mounted on the sub-stage isolates the stage from mechanical disturbances. Nevertheless, the com.bined weight of the sub-stage and stage still results in low control bandwidth and the heat generated by the electromagnetic elements supporting the stage is sz-i11 substantial.

Even though current apparatus using commutated electromagnetic means is a significant imp rove men t over prior co-nimut--atorlless ones, the problems o-- low control and interferometer -nte---,erence Dersist. in such an anna--atus, a sub-stage is moved magnetically in one linear direction and the commutated electro-,naa.--e---ic means mounted on the sub-stage in turn moves the stace lin the normal direction. The sub-stage is heavy because it carries the magnet tracks to mo-,,e the stage. Moreover, heat dissipation on the stage compromises accuracy.

it is also well kno,..,-p. to move a movable (stage) in one long linear direction (e.g. more than by uslIng two of' the lin-ear motors in parallel where and magnet are combined. In this case, the stace is cuJded by sc-,-ie sort of' a linear guiding mem-ber and driven in one ',near direction by a linear motor installed -parallel the guiding mer,-,ber. When driving the stage only to the c-n) coi 3- extent o' extremely small stroke, the aljJdless structure based on the combinat-ion of several elect --o,-,,acne ti. c actuators, as disclosed in the iD--ior art mentiloned be..Lore, can be ado.Dted. However, in ordel- to move the guideless stage to a long distance iIn one a snec-all-., structured elec-romaSTner---c actuator as in the arts becomes necessary, causing the size 0'-": the a-,:)nara--us to become larc:e-, and as a result, generating problem of consuming more electricity.

it is an object of the present invention to make it possible for a guidless stage to move in the direction of a long linear motion usin,-g,electror-,agnetic force, and to -orovide a lcht weight apparatus in which low inertia and high re. sponse are achieved.

Furthermore, it is an object of the iDresent invention to nrovide a c-uJdiess stage apparatus -uslnc commercilally available reaular 1-1near motors as elec --ro-,,,ac::-,etic actuators for one linear direction motion.

Further-more, it is an object of' the present invention to Provide a g-uideless stage apparatus capable o_f active and precise 1Dosition control for small d--'-sz)lacemez-,ts without any contact in the direction orthoconal to the lona linear motion d-irecz-on.

Furthermore, object of' the present inve---tion to =ovide a completely non-contact. stage annaratus by providing a movable member (stawe body) to move in one linear d---ec-ion and, the second movable ne-mber to move sec-ien,--ialiv in the same direction, constantly keer)Jng a certain snace in between, a,-idprovidng the force (action and reaction force) in 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 non- contact stage apparatus capable of,oreventing the positioning and running accuracy from deteriorating by changing tension of various cables and tubes to be connected to the non-contact stage body which moves as -it supports an object.

Furthermore, -it -Js an object of the present invention to provide 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 mores 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 bearina which opposes said balanc-ing portion to said base wit- hout contact therebetween, whereby said balancing portion moves in response to a movement of said movable stage, with a movement component in -the direction opposite to the direction of movement o'j'-- 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 a magnetic member one of opposed sides of the stage on the driving frame. Both motors drive in the same direction. By driving the 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 any mechanical contact with said base.

motor includes a coil member and which is mounted on one of the and the other or w1-,ich is mounted motors slightly different amounts -G- By restricting the stage motion to the three sDecified degrees of freedom, the a-oiDaratus is s--:mnle.

Bv using electromagnetic components that are co-,n.merc-allv available, the apparatus desan is easily adaptable to changes in the size ozz the stace.

This high accuracy positioning apparatus is ideally suilted for use as a reticle scanne-- in a scanning exposure system by providing 1 - smooth and nrecise scanning motion in one!-',near direction and ensuring accurate alignment by controlling small displacement mot-Lon perpendicular to the scanning direction and small yaw rotation in the Dlane.

other aspects and features and advantages of the.

present invention will become more apparent uDon a Derusal of the following specification taken in conjunction with is the accompanying drawings wherein similar characters o.

ref-erence indicate similar elements in each of the several views, and in which:

I Fa. 1 --'Is a schematic perspective view of apparatus in accordance with the -oresent invention.

."ig. 2 is a to-D iDlan view o_f the an)r)aratus sho%m in is Fig. 3 is an end elevational view o."c the structure s.how---i in Fic. 2 taken alona line 3-3, -n. the d-recion o the arrows.

Fic. 4A is an enlarged perspectilve, partially exploded, view showing the carr-Jer/--f:::ollowe-- structure ofE Fig. 1 and exploded from the position-ing guide.

- Fig. 4B is an enlarged horizontal sectional view o.L 1DOrtiOn of the structure shov-n in Fia. 5 taken along line 45 in the direction of the arrow.

Fig. 4C is an enlarced elevational sectional view of a portion of the structure shown in. Fig. 2 taken along line 4C in the direction of the arrow but w-1.th the voice coil motor removed.

Fig. 5 is an- ele-jational -sectional view of a portion of the structu--e shown -in Fig.. 2 taken along line 5-5' in the direction of the arrows.

Fig. 6 is a block diagram selhematilcally illustratin.g the sensing and control systems for controlling the Dosition o'-" the stawe.

Fic. 7 is a plane view, similar to Pic. 2, illustrating the z)re-te-red embodiment of the -present invention.

Fig. 8 is an elevational sectional view of the structure shown in Fia. 7 taken along line 8-8' Jn the direction o_f the arrows.

Figs. 9 and 10 are much simplified schematic views simi-lar to F-AIcs. 7 and 8 and illustrating still another em.bodiment o._" the nresent invention.

Whille the zresen-- invention has anolicab--,!-"tv Senerally to electromagnetic align-ment syst-ems, the -,,,--e-jE7erred e-,,-Lbodiment involves a scanning apparatus for a stage as illustrated in 'Figs. 1-6.

Ret:erring now to the drawings, the Dositionins aDna--atus io o_f the present invention includes a base structure 12 above which a reticle stage 14 iS SUS-Dended and moved as desired, a _reticle stage position tracking laser -Jnterj"'--:e--ometer system 15, a position sensor 13 and a 7Dosition control system 16 operating from a CPU 16' (see Fi.g. 6)-._ An elongate positioning guide 17 is m--unzed on th.e base 12, and support brackets 18 (two brackets in the illustrated embodiment) are movably supported on the guide is !7 such as by air bearings 20. The support brackets 18 are connected to a driving assembly 22 in the ozE a mac---netic track assembly or driving frame for drivina the reticle stace 1,1 in, t"-mie- X and small yaw rOzation.

1 The drivi-a frame includes a nair of parallel spa-ced apart magnetic track armis 24 and 26 which are connected together to form an oDen rectangle by cross arms 28 and 30. 1 n thl e erred embodiment the drIving frame 22 is movably sunoorted on the base structure 12 such as by air bearings 32 so that the frame is free to move on-the base structure in a drection aligned wth the longitudina' axs Of the i - L --- gu, ide 17, the pr inc ipal d i rec t ion in whi ch- the s cann mo!_-ion of the reticle stace is desired.

lone directionll or a d--"rec---ionit applies to movement of frame 22 or the reticle S?--age 14 either 0-- back in the X direction along a line aligned with the lonc:tud-nal axIs of the- cuide i-.

Referring now to Fas. 1 and 5 to ex=lain further _in detail, the elongate guiding member 17 in the X direction has front and rear auiding surfaces 17A and i713 which are io 1 is almost ne=endicular to the su--face 12A of the base structure 12. The front auiding surface 17A is against the rectanaular driving frame 22 and the a- bearing 20 k-. -- whi-ch is ifixed to the inne-r side c-' the suDnort bracket 15, A support bracket 1-8 -:.s mounted on each end of the upper surface of the arm 24 which is parallel to the guiding member 17 of the d-riving frame 22- Furthermore, each support bracket 18 is formed in a hook shape so as to st-raddle the u-id-ing member 17 in the Y direction and with the free end against the rear cudng surface 17-: of the rear side of the guiding me-,-Lber 17. The ailr bearing 201 is fixed inside the free end of the support brackets 18 and against the rear quiding surface 179. Theref'ore, each of the support brackets 18 is cons t- ra ined in its d-sr,,lace-,-,tent in the Y direction by the guiding me-mber 1-7 and a-';r bearings 20 and 201 and is able to move oniv in the X Now, accordinS to this flirst e-,,L:,od-Jm,,ent O:E the Present invention, the air bearings 32, which are -f--;4.xed to the bottom surfaces of the four rectancular narts of the dr---'ving f:rame 22, make an air layer leaving a constant: cap (i several pm) between the 1Dad sur-face and the surface 12A of the base structure!2. T1ne dr-Jv--'lng frame s buoyed uD rface 121 and supported De-l:)endJcularly (Jn Z from the su direction) by the air layer. It will be ex-,)la-ned in detail- later, but in Fig. 1, the carr-Ler/follower 60 Dositioned above the upper Dart of-. the elongate arm 24 I'S Dositiloned latera--',--,v in the Y d ings 66A and 66B supported by a bracket 62 aca.;nst onposite surfaces 17-2k and 179 of guiding menDer 17 and vertically in the Z direction by a-J---beari-'ncs 66 above the sur''ace 12A of the base structure 1-2. T'rus, the carrier/follower 60 is nositioned so as not to contact any part the driving frane 22. Accordingly, the drivincs frame 22 moves only in one linear X direction, c-iu,-ided above the base sur-,F'ac12A and lat-erally by the g-u-4d-7,g member!7.

Re-ferring now to both Fig. 1 and Fig. 2, the st--ucture of the reticle st-ace and the driving frame 22 wM be e=lained. The reticle, stage 14 includes a main body 2 on which the reticle 44 is Dositioned above an opening 46. The reticle body 42 includes a pair of oppo-sed si-des 42A and. 42B and is positioned or suspended above the base structure 12 such as by air bearings 48. A plurality of inter-ferometer mirrors 50 are provided on the main body 42 of the reticle stage 14 -Ll"or operation with the laser interferometer position sensing system 15 (see Fig. 6) for 1 L_ - - determining the exact position of the reticie stage which is to L-he position control system 16 in order to direct the annrcD---ate drive sJcnals -for r.-,ov-Jng --et--cle stawe as des.--ed.

Primary movement o-"': the reticle stage i4 is accomnlished with first electromagnetic drive assembly or- means in the form, OIL sez)a.--ate drive assemblies 52A and 525 on each o-E the opposed sides 42A and 4-25, respectively The drive assem-blies 52A and 521 include dr-Lve coils 541and 5,l fixed-ly mounred on the reticle staae i,- at the -2A and 25, resnectilvely, Lor cooperating with mapiet tracks 56A and 56B on the magnet -track a-ms' 24 and 26, respectively, of the drive frame 22.

While -i- the ure-.Lerred embodiment o--1E the invention the rr,"ac-necoils are mounted on the reticle stage and the magnets are mounted on the drive -i:.:rame 22, the positions of these elements of' the electromagnetic dri've assembly 52 could be reversed.

Here, the structure of the reticle stace!4 will be e=lained further in detaill.

As shown in -rJLc. 1, the staze body 12 is installed so that it is ree to m, ove "n the Y d---ection--'In the rectana-ular space inside the driving frame 22. The air bearing -8 f ixed under each of the four corners of the stage body 2 makes an extremely small air gap between the pad surface and the base surface 12A, and buoys up and supports the entire staae!4- _from the surface 12A. These air bearings 48 should preferably be -ore-loade..' ty to the surface L,pes with. a recess for vacuumm attraction 4- - 12A.

As shown in Ficr. 2, a rectangle opening 46 in the center of the stacre body 42 is provided so that the 1Drojected image of the nattern, on -the reticle 4 can go through. In order for L-he projected imaSe via the rectangle onepnc 46 to pass through the projection optical system PL (See F-i-g. 5) which is installed below the rectangle open-Lng, there is another onenina 121 provided at the center uart c--1' the base structure 12. The reticle 414 :2 U ---is loaded = the ton surfEace ofE the stage body by c!a7i.z)i-nc me-m-bers 42C which are protrusively placed at four points around L-he rectangle openina- 46, and clamped by the the interferometer mirror SOY, -,,;h-Jch is fixed,' near the side 2B of' the stage body 42 near the arm 26-, has a ve--tical elongate reflecting surface in the X direction which length is so-,-.e'-n-wal--- longer than the movable stroke oZE i the stage 141 Jin the X di-rection, and the laser beam LSY the Y-axs -i-ter-=e-omete-.y- is incident on the re-'lect-JncsurfEace. in FJa. 2, the laser beam LEY ',s bent at a right anale by the mirror 12D which - j s f i x e-.-; on the side o--lc the base structure 12.

Re.ferrina now to Fig. 3 as a partial cross-sectional d--awinc o-E the 3-31 view in Fa. 2, the laser beam LSY which is incident on the reflecting surface oJE: the interfe-rometer mirror SOY is placed so as to be on the same miane as the bottom surface (the surface where the cattern is formned) of the reticle,i wh-ic'--i is mounted on the c--;amDi-ng member 2C. -Furthermore, in Fig.

bear-Jnc-r 20 on the end side of the support brackets 18 against the guiding sur-face 17B of the gu.-.1d--Jncy member 17 is also shown.

Referring once again to Figs. 1 and 2, the laser beam LBX1 from the Xlaxis interferometer is incident and reflected on the interferometer mirror SOXI, and the laser beam LBX2 from the X2-axis interferometer is incident and is reflected on the inter--'e--ometer mirror 5OX2. These two mirrors 5OX1 and 5OX2 are structured as corner tube tyue mirrors, and even when the stage 14 is in yaw rotation, ng ax-. s they always T-,,aJnta--,n the incident axis and reflectl of the laser beams parallel within the XY plane.

Fu--m-he=,.ore, the block 12C in Fig. 2 is an opticall block such as a nrism to orient the laser beams LBX1 and LBM to each of' the mirrors 5OX1 and 5OX2, and is fixed to a part of: the base structure 12. The corresponding block fEor the LBy laser beam is not shown.

in Fia. 2, the distance BL in the Y direction between eac',, of: the center lines c-'-' the two laser beams L12X! and L9X2 is the -enwth of the base line used to calculate tne amount of- yaw rotation. AccordJnciv, the value of the di-f-ference between the measured value Axi in the X direction o--," the X!-axis and the measured in the X direction of the X2axis ;alue nX2 inter-":erome:er d-vde---, by the base line lenah EL is the aDnrox-r,,ae amount of yaw rotation in an extremely small ranae. Also, half the value of: the sum of the AXI and 6X2 rez5resents the X coo--d-inal-e)osJLtion olf: the e-,-i-J.:.re stage!-L-.

calculations are done on the high speed dicital processor in the position control svsLem 16 show---.n in Fic. 6.

Purthexrmore, the center lines of each c-E the laser beams LEX1 and LBM are set on the same sur-frace where LIne Dattern is on the retic-le ex-ens-on of the line GX, which is in Fc. 2 and dilvides in '.-al--7 the snace between each of the center lines of laser beams L5Xl io and LEX2, and the extension of the laser beam LBY inersect- within the same surface where the pattern is formed. And furthermore, the ontical axis AX (See Figs. 1 and 5) also crosses at th;LS intersection as shown in Fig. 1. 1 n 1, a slit shape llumination 'i eld LS wh ch J ncludes the is optical axis AJX is shown over the reticle 44, and the Dattern imace o.,' the reticle 4 is scanned and exposed onto the Dhoto-sensitive substrate via the projection ontical system PL.

Furthermore, there are two rectangular blocks 90-k and 905 fixed on the side 2.'". of the stace bodv 12 in F-c:s. 1 and 2. These blocks 90A and 902 are to receive the driving force in -the Y direction from, the second electro-magnetic actuator 70 which is mounted on the carrie--/-Eoll--wer 60.

Details will be exDia-ned later.

The driving coils 54A and 54-B which are f ixed on t--e both sides of: the stage body 42 are --E-or-,n.ed flat. Darallel to the XY zlane, and cass th-rough the mawnetic flux space in the slot which extends in the X drectJo:, o-, the r,..ac:ne-Jc track 5621A. and 565 w--'hout any contact. The assembly OZE the -;-iving co-ii 54 and the magnetic track 56 used in the Dresent embodiment is a commerczally easilly, accessible linear motor for general Purposes, and it could be with or without a commutator.

Were, co-1s.-'.der-in(: the actual design, the movina stace 11.1 is mostly bv the size of' the reticle 44 (the amount o_ movement recru-i--ed at the time of scan-i-i-ing-LE:7or exposure and the amount of movement needed at the tilm.e of removal of the reticle --1-ro,-., the i 1 1 1 ontical svst:ern. to chance t'-e re--lele).

case of the cresent eribod--'1r-,.ent, wImen a 6- --'nc-. ( 15. 2 L. c n) reticle is used, the mov-ing:stroke is about 30 cr,.

T.s mentioned before, the dr-v-:na frame 22 and the x% - -1 -1. - J_ 0 stage!4 are independently buoyed up and supported on the base surface 12A, and at the same tine, magnetc action and re - act-ion force-is applied. to one another in- the X direction only by the linear motor 52. Because of that, the 1 aw of' the conservatIon. c,:-,, momentum -is.seer- between the driving -'s frame 22 and the stage Now, suDnose the weight of the entire Ireticle stage is about one f if th the entire weicht of the 22 wh_ then the ch the brackets 18., movement o-f 30 cm o.-" the stace!4 in the X direction nakes the frame 22 r,-,ove by 6 cm backwards in the X direction. Th-is- means that the location the center- of the base structure 12 is essentially fixed in the X direction.

in the Y direction, there is no movement of any heav-y object.

chanae in the location of the center of the cra.,-Jty in the Y direction is also relativeiv _fixed.

The st-we 1,,! can- be moved in the X direction as described above, but the moving coills and the Stators 563) ofE the linear motors 52 will interfere wIth each other (collide) in the Y d. i -- e c t il o n W il tIn o U a n X ditreCtion actuator.

Therefore, the carrie--/--,'oiiow=-r 60 and the second electromagnetic actuator 70, which are the -Is- characteristic components of the present invention, are -:Drov-ded,' to control- the stage 1-,- in the Y direction.

Re'errJnc no.o; to Fics. 1, of them will be explained here.

io is 2, 3, and 5, the struct:,ures As shown in Fic. 1, the carrier/follower 60 is movably installed in the Y d-Lrection via the hook 'like s,-,-a-Dort: bracket 62 w,,-ch straddles over L-he guiding member 17. Furthermore as evident frorm Pia. 2, the carrier/fol lower 60 is placed above the arm, 24, so as to maintain a certain space between the stage 14 and to the arm 2,-, resnectively. one end GOE-E o_ the (the body 2) carrier/.;ol lower 60, is substantially protruding inward (toward the stage body 42) over the an-m 24. Inside this end nart 60E is fixed a driving coil 68 (sarme shape as -the coil 54) which enters a slot space of th-e magnetic track 56AL.

Furthermore, the bracket 62 supported air bearing 66-k (See Pigs. 2, 3, A and 5) against the guiding surface 17A o-"" the auidina member-!7 is fixed in the s-Dace between the cudna member 17 o"" the carrie r/ -Follower 60 and the arm.

2 4. The air bearing 66 to buoy up and suz)Do---t the carrier/--ollow=-r 60 on the base surface 12A is also shown in Pia. -.

The air bearing 66B against the -au-iding surface 175 of -the cruiding member 17 is also fixed to the fIree end o=L su--)nort bracket 62 on the other side 0--- the hook from a- I- -- bearing 66-1% with au-:"d4-amem.ber 117 th.erebeween.

Now, as evident from Fig. 5, the 60 is arranged so as to kee:D certain s-Daces with res-iect to both the magnenic track 56A and the staze body 42 in the Y and Z directions, resne--t-ive"lv. Showrn in F-Lg_. 5 are the projection optical system PL and column rod C3 ZO SuID'-,Z)Ort the base structure 12 above tIhe 1Droject---io,-i onz-Jcal system -I E; - P-'.

Such an arrangement is typical _for a:Drc-;lect-Lon 1 alianer, and unnecessary shift of the center of the grav-,"tv o-E t-e structures above the base structure 12 would cause a lateral shift (mechanical distortion) between the column rod CE and the projection optical srste-,,-i PL, and thus result --:In a de-flection of the i-mage on the nhotosens--"'---:ve substrate at the time of ex-posure. Fence, the merit OZE the device as in the uresent er-,ibod--:ment where -,he motion 0-"- the stage ic- does not shift the center of the aravity above the base structure 12 is sub-stantial.

Furthermore referrina now to Fig. 4A, the structure of the carrier/follower 60 will be exmlained. In Fig. -A, the carrier/follower 60 is disassembled into two parts, 60A and 605, for the sake of facilitating one's undersl-a--i,-4i-na.

As evident from Fic. 4A, the driving coil 6s to miove the carrier/follower 60 itself in the X direction.1s fixed at the lower Part of the end 60E of the carrier/ -fol lower 60.

Furthermore, the air bearlIng 66C is placed ac:a-inst the base structure 12A on the bottom surfa-ce of the end 60-7 and helms to buov um the carrier/follower 60.

Fence the carrier/follower 60 -is s.u::)r)orted in the Z with the -L'ollow-ing three points, the two air bearings 66 and one air bearing 66C, a-rid is cons ned in the direction for movement in the X direction by air bearincs 66A and 6052. What is imnortant in this structure s that t-e second electromagnetic actuator 70 -is arranged 1 - - back to back with the su-,>i:)ort bracket 62 so that wnen tne actuator generates the force in the Y reaction _forces in the Y direction between t,-e the carrier/fol lower 70 actively act umon 6615. and 662 which are inside the In other words, arranging the actuator 70 and bearings 6GA, 665 on the line parallel to the stace i, and air bear--lnc:s bracket 62.

the air y - a 7.. s i n t 1, -- io 3 0 XY plane helms prevent generating unwanted stress, which micht deform the carr-:.e.--/-f ol lower 60 mechanically when the actuator 70' is in oneration. Conversely, it means that it is mossible to reduce the weight o-E the carrier/fol lower 60.

As evident from, 2, 4A and - described above, the macnetic track in the arm, 2, o-f the _frame 22 provides magnetic -flux for the drivi-nw coil 54A on the stage body 2 side, and con.-current--lv r=vides maanet-i--L'I"Iuy., for the driving coil 68 for the carrier/fo-, lower 60. As for the air bearings 66A, 669 and 66C, a vacuum pre-loaded type is preferable, since the carrier/.Eol lower 60 is light. Besides the vacuum pre-loaded type, a magnetic pre- loaded type is also acceptable.

Next- with re-Eerence to Figs. 3, 4B and 5, the second actuator mounted on the carrier/follower 60 will be explained. A second electromagnetic drive assembly in the orm of a voice coil motor 70 is made a voice coil 7, uD clattached to the main body 42 of the reticle stace 1-4 a.nd a Eol-lower 60 to move the magnet 72 attached to the carrier/-stage!,! for s-.,,al-ld-;.si31ace-, nents in the Y direction in the niane of the L-ravel of -the stage 1, orhogo-n.al to the X direction long linear motion produced. by the driving assembly 22. The mositions of the coil 7, and mag.Innet 72 could be reversed. A schematic structure of the voice coil motor (VCM1) 70 is as shown in Fics. 3 and 5, and the detailed structure is shown in Fig. 43. Show- in Fig. E VCM 70 sectioned at the horizontal Diane shown with an arrow =13 in Fic. 5. in Fi g45, the magnets 72 of the VCM 70 are fixed onto the side. And the coil- of the VCM 70 com,nrises the coil body 74-A and its supporting part 74B, and the supporting mart 749 is fixed to a connecting clate 1 is 92 (a plate vertical to the XY plane) which is riglidly laid across the two rectangular blocks 90A and 90B. A center line Yjf of the VCM 70 shows the direction of the driving force of the coil 74, and when an electric cur-rent flows through the coil- body 74A, the coil 74 dis-Diaces into either positive or negative movement in the Y d-'.rectio-n in accork-ance with L-he direction of- L-he current, and wenerates a force corresuondent to the amount o-E the current.

ijormnally, in a commonly used VCM, a ring-like damper or bellows areprovIded between -the coil and mac:net so as to keep the ga-p between the coil and magnet, but according to the present embodiment, that can is kept by a follow-up motion of the carri er/f cl lower 60, and therefore, such supporting elements as a damper or bellows are not necessary.

In the present embodiment, capacitance ga"D sensors 13A and 13B are provided as a positioning sensor 13 (see Fig. 6) as shown in Fig. 45. in Fig..,!-B, electrodes for canacitance sensors are iDlaced so as to detect th-e change n the gaiD in the X d-rec-o-i between the s-:de s,-,,-,zace of the rectancrilar blocks 90- and 90B facing with each other in the X direction and the side surface of a case 70' of the VCM, 70. Such a positioning sensor 13 can be anywhere as far as it can detect the crap chance J= the Y direction between the carrier/follower 60 and the stace (or the bo,-",y 42). Furthe-lrmore, the type o_f the sensor can be any o-f2: a non-contact type such- as inductive, ultrasonic, or air-micro system.

The case 701 in Fic. 2 is -formied w-it'., the carr lower 60 in one, and placed (s.Da!---Jally) so as not to contact any member on the retcle szace 1A side. As or the car) between the case 701 and the re--zanaular blocks 90A and 90B in the X direction (scanning direction), when - C) .5 2,3 j0 the gap on the sensor 13A. side becom es wider, the gaID on the sensor i'I B side becomes smaller. There-fore, if the difference between the measured 9 ap value by the sensor i2A and the measured c-7aiD value by the sensor 135 is obtained b,,,, eicher digital operation or analog operation, and a direct ser-jo (J.'5eedback) control system which controls the drivinw current of the driving coil 68 for the carr-:Ler/.:o'-.1-ower 60 is desicned usinc a serve, driving circuit w-,ch makes the gap difference zero, then the carrier/follower 60 w-3l automatically a follow-up movement in tIne X direction always keeping a certain space to the stage body 42. Or, it is also iDossible to design an indirect servo control-system which controls an electric current flow to the driving coil- 68, with the operation of position 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 gap sensors 13A and 13B differentially.

in the VCM 70 as described in Fig. 43, the gap between the coil body 74A and the rnnagnet 72 in the X d-i.-ect-ion (non-energizing direction) is in actuality about 2 - 3 mm. Therefore, a followup accuracy of the carrier/follower 60 with resnect to the stage body 42 would be accer)table a-t around .5 - i mm. This accuracy depends on how much of the yaw rotation of the stage body is allowed, and also depends on- the lenath of the line in the KX d-ectio.-i (enercrizncr direction) of th.e coil body 74A o.:

the VCM 70. Furthermore, the degree of the accuracy for this can be subs tantially lower than the crecise i)osition--7nc- accuracy for the stage body 2 using an interferometer (e. a., +0.03 pm supposing the resolution of the interferometer is o.01 gm.) This means that the servo 0 is system for a follower can be designed fairly simply, and the amount of cost to install the follower control system,,;ould be s-mall..-ur!-- hermore, the line KX in F-,-. B is set so as to go throu-c'.ri the center of the gravity 01- the entire stace 14- = the XY plane, and each of centers of the pair of the air bearing 66.tlt and 69 provided insilde the support brackets 62 shown in Fig. 4 is also nositioned c-. the line:Y in the XY plane.

Shown in Fig. 4C is a cross -sect ional part which includes the guiding member 17, carrier/.--L:'ol!owe-- 60, and the magnetic track from the direction of the arrow 4C in Fig. storing- the r%netic track 56A is buoyed up on the base surface 12A by the air bearing drawing of the t n e 56A sectioned 2. The arm 4 and supported 32, and the carrier/-:L7ollowe-- 6o is buoyed up and sunoorted on the base surface 12A by the air- bearing 66. At this time, the heisht o."z the air bearing 4-8 at the bottom surface of the stage body 42 (see Fics. 3 or 5) and t.-ie hec:h- 0-- the ailr bearing 32 are determined so as to place the driving coil on the stage body 42 side kee-Ding a 2 - 3 mm gap in Z direction in the slot snace of the macnetic track SGA.

Each c-lz the spaces between the carrier/fol lower 60 and the 24 in the Z and Y directions hardly changes because they are both guided by the common cr-uJdina member 1-7 and the base s-jr-lEace 12A. Fu--ther-,,-iore. even i-'," there a in the 1'n the Z dJ-ectJon between the nart on the base surEace 1211- where the air bearing 32 at the bottom surface of.' the driving frame 22 (arm 24) is g-u,-ided and the part on the base sur-face 12A w.ne--e the air bearlinz 8 at the bottom surface of the stawe body guided, as long as the dif-fere-nce is precisely constant withlin -the moving stroke, the car) in the Z d--lrect-iOn j S between the magnetic track 56.k and the driving coil 54A is also preser- jed constant.

Furthermore, since the dr-.vinc: coil 68 the carr-:i.er/-.L:ollo,,;er 60 is cricTinally fixed to the carrier/.Lc'ollo.,jer 60, it is arranced, maintaining a certain f gap ol- 2 - 3 mm above and below in the slot space of the magnezic track 561^. And the d---Lv_-,--ic coil 68 hardly -i- the Y direction with. resDect to the r-,,agnet-ic track Cables 82 (see Pig- 2) are provided for directing the i 0 is signals to the drive coils 54A. and 54B on stage -14-, the voice coil motor coil 74 and the carrier/follower drive coil 68, and these cables 82 are mounted on the carrier7 f ol lower 60 and guide 17 L-hereby 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 staae 14.

Therefore, referring now to Figs. 2 and 4A, the cable ssues will be described in detail. As shown in F:

9. 2, a connector 80 which connects wires of the electric system and tubes of- -the air -pressure and the vacuum system (hereinafter called "cables") is mounted on the biase structure 12 on one end of the guiding mer,-Lber 17. The connector 80 connects a cable 81- from the external control system (including the control system of ai--- pressure and vacuum system besides the electric system control syst-em shown in Fia. 6) to a flexible cable 82. The cable 82 is further connected to the end uart 60E of the carrier/follower 60, and electric systern wires and the ailpress- are and the vacuum system tubes necessary fror the stace body 42 are distributed as the cable 83- As mentioned before, the VCM 70 works to cancel a cable's drag or an influence by tension, but sometimes its influence anbears as moment in unexpected direction between is the carrier/follower 60 and the stage body 42. In other words, the tension of the cable 82 gives the ca-'-r-Ler/-L-ollowe-.- 60 a --Force to rotate the guiding s=face of the 9-,-,-idina- member 1-7 or the base surface 12A, and the tension of the cable 83 gives a -fcrce to the carri er/.Eol lower 60 and the stage body to rotate a IC i v el v.

One of these morments, L-he constituent which slifts follower 60, is not proble,-,iatic, but the one which shifts the stace body in X, Y, or e direction (yaw rotation dir ection) could affect the alignment or overlay accuracy. As for in X and 6 directions, shifts can be correct-ed by'&consecut-ive drive by -the two linear motors (54A,56A,545,565), an.d as for in the Y direction, the shift can be corrected by the 'VCM 70. in the present e,,nbod-5-;nen,L., since the weight of the entire stage 14 can be reduced subs tan t ially, the resDonse of the motion o-':' the stage 14 by VCY. 70 in the Y direction and the response by the linear motor in X and 9 directions will be extremely high in. cooneration with the completely non-contact guidleSS structure. Furthermore, even wher. a micro vibr-ation (micron order) is generated in the carrier/f ol lower 60 and it is trans "":erred to the stage 14 via the cable 83, the vibration (-"rom several Hz to tens of Hz) can be sufficiently canceled by the above men-Lic-ie-.-' high response.

Now, -':,:La. 4A shows how each of the cables is d-st---o'.bu,ted at the carrier/-La'ol lower 60.:-:ach of the drivinw signals to the drivilng coil 54A, 54.5 for the stace body 12 and the dr-iv--'lnw coil- 74 of the VC1M 70 and the detection signal from the -Dosition sens.or 13 (the gap sensors 13A, 7-3B) go through the electric syste-m wire 82A ftorm the connector 80. The pressure gas and the vacuum to each of the air bearings 48 and 66 go through the pneumatic system tube 823 from the connector the driving signal to the drivng coil 5,A and 5,E goes through the electric system w-Zre 832-1 which the stage bod-,,r 2, and the pressurized gas bearing 48 and the vacuum for the clamping through the pneumatiC system hoses 839.

Furthermore, it is preferable to have a se--)arate line 80. On the other hand is is connected to or the a meT,dDe-- 42C co or 'or the -,-)neumatc system.1- the a- bearn-s 20, 201 and 32 of: the driving fra-,re 22, inde:Dendent ot' the one shown. in Fa. 2. Also, as shown in Ficr. 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 the tension or vibration the stage body 42 receives Only to Y direction as much as possible. 7n that case, the moment can be canceled only by the VCM, 70 wit-h the highest response.

Pe-ferring now to Pigs. 1, 2 and 6, the 1Dosit-5c)rLna of.

the reticle stace 1.61 is accomplished,i-st knowing its existing posit-Lon utilizing the laser inter-ferometer s-,7s:iem !S. Drive signals are sent to the reticle stage drive coils 54A and SAIS for driving th.e stage 1, in the X direction. A difference in the resul-in( - k_ A- J_ L-.1 drive to the onoosite sides 42A and 42E of the reticle stace 14 willoroduce small yaw rotation of the reticle stac:e 14.

a nroD-iate drve s4gnal to the voce coil 72 of vo-ce coJ3 p motor 70 oroduces small d-isniace,,nen-s of the reticle s--a=e 14 in the --,j direction. As the position of the ret." cl, e staae!,!-I chances, carrie-/-.c:ollower coil 68 'follow the reticle stage the anDl-ed drive forces assembly or drive _frame movement o-., the reticle a drive s-wnal is sent to the SC -0 causing the carr-ie--/Eollowe 14. Resulting reaction;:orces tO will- move the rmagnetic track 22 in a direction o-DDosJte to the stage 14 to substantially r,.a-ntai- the center of aravity of the apparatus. 7-t will be aD-orec-ated that the counter-weicht 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 descrbed above in order to control the stage io is system according to the rresent em-bodiment, a control syse-,n as shown in Fis. 6 is -AInstalled. This control system -in Fig. 6 will be further explained in detail here.

XI driving coil and X2 driving coil composed as the dr-i-j-.ng coils 5,A and 5,g o:E two linear motors respectively, and Y driving coil composed as the driving coil 72 of the VCM 70 are placedin le reticle stage 14, and the driving coJl 68 is placed in the carr-.'er/-,Eollower 60. Each of these driving coils is driven in res:Donse to the driving signals SX1, SX2, SY1, and SAX, respectively, from -the position control system 16. The laser interferometer system which measures the coordinates position of the stage 14 comprises the Y axis interferometer which sends/receives the bean, LBY, the X1 axis.-i--ter-Le.-7.-o-,,leter which sends /rece ives the beam L5Xl, and the X2 axis interferometer which sends/receives the beam LBX2, and they send iDosition in.o--m.a-.iO'n for each of the direct-Jons of the axes, iFY, !FX1, i-FX2 to the position control system 16. The position cc-n-trol system 16 sends two driving s5anals 5XT and SX2 to t'-e driving coils 54.A_ and 54B so that the di--,"--cere.-ice between the nosition-!FXI and!F-EX2 in the X d.rec---on will become a iDreset value, or in other words, the yaw rotation of the reticle stage 14- is maintained at ne snecified amount. Thus, the yaw rotatilon (in E) direction) pos-.'lt- ionJ-c by the beams LEX1 and LBX2, X1 axis and X2 axis interferometers, the -position control systerm 16, and the driving sianals SXI and SX2 is constantly being conducted, once the reticle 44 is aligned on the stace body 12, to mention the time of,the needless exmosure.

Further-miore, L-he con rol system 16, which obtained the current coordinates uosition of the stage 14 in the X direction from the average of the sun of position -in..t:om-.ation!FX! and IFX2 in the X direction. sends the driving sig-nals SX1, SX2 to the driving ccils 54A and 5,E, respectivelly, based on the various commands front the Host CPU 16' and the infor-mation CD for the narameters. Especially 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 driving coils 54A and 54B to give the same or slightly dif-ferent forces as needed.

Furthermore, the position _infor-mation IFY from the Y ax-'s interferometer is also sent to the control system 16, and the control system 16 sends an optimum driving sianal SAX to the driving coil 68 of the carrlier/-l'ol lower 60. At that 'ULme, the control system, 16 receives the detection.

signal S pd -from the position sensor 13 which w.,=-asures the snace between the reticle staae 1,1 and -the carr-er/-.,::ol-lo,,ver in the X direction, and sends a necessar---y sig-nal SAX to make the signal 5 pd into the preset value As mentioned before, the follow-up accuracy for the carr-ier/--t:ollowe-- 60 is not so strict that the detection signal S pd of the control system 16 does not have to be evaluated strictly either. For exa-,r,-jle, when controlling the -motion by reading the mosition iFY, I-FXl,!FX2 every imsecond from each of the -interferometers, the h-5c:h speed r)rocessor in the control system 16 samples the current cif the detection signal 5.. each time, determines whether the value is larce or small compared to the reference value (acknowledge the direction), and if the deviation surpasses is is a certain point, the sJanal SLX in iDrono--t-ion to the deviation can be sent to the driving coil 68. Further-m=e as mentioned before, it is also accentable to install a control svstem 95 whilch directly servo controls the dr;Lvinc:

c11 68, and directly controls the follo.,;-uu motion of the 01 L carri er/ f ol lower 60 without coing through the position control syst-- e,-,i 16.

Since the nQv-in sta=e system as shown has no attachment to constrain it in the X directi-on, small in.f.luences 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 of the base reference surface 12A or friction between co-mnonents. One sim-jle method is to use weak bummers (not shown) to prevent excessive travel of the dri've assembly 22. Another s-imDle method.-is to turn off the air to one or more of L-he air bearings (32,20) used to auJde the drive bly 22 when the drive assembly reaches close to assemb the end of the stroke. The bearing(s) can be turned on when the drive bec:-ins to move back in the o-jEos-te direction.

More -precise methods recuire monitoring the position of the drive assembly by a measuring means (not showrn) and aniD'-1y--:,ng a driving force to restore and mai-,ita.:.n the correct position. The accuracy of the measurIng means need not be iDrecise, but on the order of 0.1 to 1.0 mm. TI, e driving force can be obta-Lned by usincr another linear motor (not show--.) attached to the drive assem-biv 22, or another motor that is coupled to the drive assenniv.

Finally, the one or more air bearincs (;-z6,66A,66B) o:E the carrier/follower 60 can be turned off:- to act as a brake during idle periods of the stace 42. If the coil 68 of the 27- ca_=ier/.Eol lower 60 is energized with the carrier/ lEol lower 60 in the braked condition the drive assembly will be driven and accelerated.. Thus, the nosition control system.

i 0 i 5 16 monitors the location of the drive asser,-Lbiv 22. When the dri've assembly dri'L-Ls out of position, the drive -.=cen-t accuracy bv assembly is repositioned with suf-inte--m-'X-te.-itly using the coil 68 of the carr-er/follc.,,er 22.

Tn the embodiment the -Dresen-- invention, the drivinc frame 22 which functions as a counter weight is installed in order to prevent the center of the gravity of .L L - - the entire system from shifting, and was made to move in' the onoosite direction from th-e stage body 2. -However, w'hen the structures in Figs. 1 - 5 are applied to a system where the shift of' 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 roblem regarding the center of the gravJl-v, some for the pof the e._:.;ec--s and function can be anclied without ma'jl- inc7 any chal.wes.

This invention r=vides a stage which can be used _for high accuracy position and motion control in th-ree decrees of freedom in one niane: (1) long linear motion; (2) sho--t linear mot-lon nerpendicular to the long linear motion; and (3) small yaw rotation. The stage is isolated fromm m ,echancal disturbances of surrounding structures by utilizina electromagnetic forces as the stage dr--ve---- D Y further using a structure for this quideless stage, a hich cont--ol bandwidth is attained. These two -factors contribute to achieve the smooth and accurate operation cf, the stace.

Description.of the Preferred E-,-,bodiment ---lC) Bearing in mind the description of the embodiment illustrated in Fics.

1-6, the preferred embodiment of the present invention is illustrated in Figs. 7 and 8 wherein the last two digits of' the nu-L-,ibered elements are similar to the corresponding two digit numbered elements in Figs. 15.

In Figs. 7 and 8, from the p_revious first embodiment, the driving- frame which functions as a counter weight is removed, and each of the magnet tracks 156A and -LSCl olo trie two linear motors is rigidly mounted onto the base structure 1-12- The stage body 143 which moves straight in the X direction is placed between the two magnetic tracks i5GA and 156B. As shown in Fig. 8, an or)en-in97'-1125 is - formed in the base structure 112, and the stage body i42 is arranged so as to straddle the opening part 112B in the Y direc tion. There are -. ':7ou- nre-loaded L - - air bearings 148 fixed on the bottom surface at both ends of: the staae body 1,12 in the Y direction, and t'npv buoy un and suiDnort the stage body 1,2 against, the base surface Furthermore, according to the present embodiment, the reticle 144 is clamped and su-.,=)orted on the ret-i---1e chuck nlate 143 which is separately placed on the stage body 142. 'T,he straight mirror 150Y for the Y axis laser interferometer and two cornemirrors 15OX1, 15OX2 for 'he X axis laser are mounted on the reticle chuck nlate 1,3. The driving coils 154A and are horizontally fixed a-- the bo--'- ends of the staSe body 14-2 in the Y direction wilth respect to the magnetic tracks ISSA and i565, and due to the control subsystem -j--f-ev-iousl-y described, miake the stage body 1, 2 run straight in the X direction and yaw only to an extremely small amount.

As evident from Fig. 8, the magnet-1.c track 155B of the right side of the -linear motor and the magnetic track 156A of the left side of the linear motor are arranged so as to have a d_ifference in level in z direction between them. In other words, the bottom surface of the both ends in the direction of the long axis ofE the magnetic track 156 on the left side is, as showrn in Fig. 7, elevated by a certain amount with a block member 155 against the base surface 112A. And the carr er/f ol lower 160 wnere the VC1M is fixed is arranged -11n the space belowthe elevated magnetic track 15GA.

The c arri e_r/fol lower 160 is buoyed up and supported by the p-l-eloaded air bearings 166 (at 2 points) on the base surface 112A1 of the base structure 112 which is ore level lbwer. '-.furthermore, two preloaded air bearings 164 against the vertical guiding surface 117A of- the straight guiding member!17, whic h is mounted onto the base structure 112, are fixed on the side surface of the carr-er/--'-:ollower 160. This carrier/follower 160 is different from the one in Fiag. 4A according to the previous embodiment, and the driving coil i68 (Fig. 7) -for the carrier/..followe-- i60 is fixed horizontally to the part which extends vertically -from the bottom of' the carrier/ f ol lower 160, and positioned in the maanet-Jc flux slot of the magnetic track 156A without any contact. The carrier/f ol lower i60 is arranged so as not to contact any part of the magnetic track 15GA within the range of' the Mov; ing stroke, and has the VCM i70 which positions the stage body i42 precisely in the Y direction.

Furthermore, in Fig. 7, the air bea---Lna i66 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 1-60 is also done based on the detection signal 'Erom the -josition sensor 13 as in the r)-evious embodiment.

In the second embodiment structured as above, there s an inconvenience where the center of the gravi y o" the entire system shifts in accordance with the shift of the stage body 1A1-2 in the X direction, since there is subst-antially no member which functions as a counter weight. It is, however, possible to position the stage body i42 Drecilsely in the Y direction with non-contact electro-magnetic force by the VCM, 170 by way of following the stage body 142 without any contact using the carrier/f ol lower i60. Furthermore, since the two linear motors are arranged with a difference in the level in, the Z direction between them, there is a merit where the sum O.L 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 stace because the force moment o-E each of the linear motors subs tantially cancels with the other.

Furthermore, since an elongated axis of action (the 0 is arranged so as to ne M in. Fig. IS) o_f the VCM.17 pass through the center of the gravity ofE the entire structure of the stage not only on the XY plane but also in the Z direction, it is more difficult for the driving Z1co-rce of the VCM 170 to give unnecessary moment to the stage body 12. Furthermore, since the me-hod of connecting the cables 82, 83 via IL-.he.carr-Jer/fo''lowe-- iGo can be applied ',n the same manner as in the first embodiment, the problem recarding the cables in the completely non-contac guideless stage is also improved.

The same 9-uideless princi-ple can be emQ-,oyed in a-other For example, in schermatic F-c-:5. 9 and 1-0, the stage 2,12, supported on a bases 212, is driven in the long X direction by a single movincr coil 25, moving within a single maanetic track 256. The magnetic track is -'0 -'s rigidly attached to the base 212. The center OZE the coil is located close to the center of gravity of' the stage 242. To move the stage in the Y direction, a Dair of: WMI's (274A,2745,27 2A,2723) are energized to provide an acceleration force in the Y direction. To control yaw, the coils 274A and 274B are eneraized differentially under control of the electronics subsystem. The VCM. magnets (272A,272E) are attached to a carri e-r/fol lower stage 260. The carrie--/.LE:ol lower stage is g-u-- 'ded and driven like the first embodilment previously described. This alternative embodiment can be utilized for a wafer st-age. Where'it is utilized for a reticle stage the reticle-can b-e-nos-1'.tioned to one side of the coil 254 and track 256, and if desired to maintain the cen.te- r of gravity of the stage 2,2 passing through the coil 254 and track 256, a compensating opening in the stage 242 can be provided or. the opposite side of the coil 254 and track 256 f_om the reticle.

Mlerits gained fro-m each of the 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 sage follow the stage via the carrier/follower. Cables connecting the carr ier/f ol lower to external devices will have a certain- amount of drag, but the stacre is free from such disturbances since there is no d-I-rect connection to the carrier/follower which acts as a buffer by deny-Jn--- the transmission of mechanical disturbances to the stage the counter-we--:,ght design -preserves the location of the center of gravity of the stag j e system durina any stac:e motion in the long stroke direction by us-ing the conservation of momentum rrinciiDle. This apparatus essentially eliminates any reactSon forces L -32 between the stage system and the base structure on which the stage system is mounted, thereby facilitazing hich acceleration while minimizing vibratonal effects on the system.

In addition, because the stage is designed 'or limited motion in the three degrees of freedom as described, the stage is substantially simpler than those which are desined 'or 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 does not require custom- made electromagnetic com-jonents 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 Triotor eliminates the second linear motor and. achieves yaw correction using two VCM1s.

While the present invention has been descrilbed in rred embodiment, the inventJon can take erms of the prefemany different forms and is only limited by the scope of the following claims.

33

Claims

1. A scanning type exposure apparatus which exposes a pattern onto an object while a stage is moved in a scanning direction, comprising: an exposure device which exposes said pattern onto said object; a base structure which supports said stage in a manner in which said stage is movable; a first drive device which moves said stage in the scanning direction; a position detection device comprising an interferometer system to detect a position of said stage; and a balancing portion which is movably supported by said base structure and moves in the scanning direction responsive to the movement of said stage.

2. An exposure apparatus according to Claim 1, wherein said first drive device has a first portion to be connected to said stage and a second portion to be connected to said balancing portion.

3. An exposure apparatus according to Claim 2, wherein said first portion and said second portion are not in contact with each other.

4. An exposure apparatus according to Claim 2 or 3, wherein said first portion comprises a coil member and said 330 second portion comprises a magnet member.

34

5. An exposure apparatus according to Claim 2, 3 or 4, wherein the movements of said stage and said balancing portion follow the law of conservation of momentum.

6. An exposure apparatus according to Claim 1, 2, 3, 4 or 5, wherein said first drive device comprises a linear motor.

7. An exposure apparatus according to any one of the preceding claims, wherein said stage is movable over a surface of said base structure via a bearing.

8. An exp?sure apparatus according to Claim 7, wherein said bearing is a non-contact bearing which opposes said stage to said base structure without any contact there between.

9. An exposure apparatus according to any one of the preceding claims, wherein said position detection device comprises a reflective surface fixed to said stage.

10. An exposure apparatus according to Claim 9, wherein said reflective surface is a corner-cube type mirror.

11. An exposure apparatus according to any one of the preceding claims, wherein said position detection device detects a position of said stage with regard to said scanning direction during the movement of said stage.

12. An exposure apparatus according to any one of the -30 preceding claims, wherein said position detection device detects a position of said stage with regard to a direction which is different from said scanning direction during the movement of said stage.

13. An exposure apparatus according to any one of the preceding claims, further comprising a control system which corrects yaw rotation of said stage based on a detection result by said position detection device.

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

15.---Anexposure apparatus according to any one of the preceding claims, further comprising a second drive device which moves said stage in a direction which is different from said scanning direction.

16. An exposure apparatus according to any one of the preceding claims, wherein said exposure device includes a projection system which projects said pattern onto said obj ect.

17. An exposure apparatus according to Claim 16, wherein said stage is located above said projection system.

18. An exposure apparatus according to Claim 16 or 17, wherein said projection system projects the pattern optically.

19. An exposure apparatus according to any one of the preceding claims, wherein said exposure device includes a mask which defines said pattern.

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20. An exposure apparatus according to Claim 19, wherein said stage holds said mask.

21. An exposure apparatus according to any one of the preceding claims, wherein said balancing portion operates without a drive source.

22. An exposure apparatus according to Claim 8, wherein said non-contact bearing is an air bearing.

23. An exposure apparatus according to any one of the preceding claims, wherein said stage comprises an opdning through which said exposure device exposes said pattern onto said object.

24. An exposure apparatus according to any one of the preceding claims, where-in said balancing portion is of a rectangular shape.