GB2329519A - 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 mask 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 mask stage by a reaction force to maintain the centre of gravity of the apparatus, the balancing portion and mask stage may be freely suspended above the base by air bearings 32 and 48. A laser interferometry system LBX1, LBX2, LBY, 5OX1, 50X2, 50Y detects the exact position and orientation of the mask stage.

Description

2329519 -I- E1 ECTROM-AGN-E-T- I C SCA.1\77-\-,--.-?\:G S T'--- nresenz:

invention relates to a mcvable stace anarazius canable of n--ec-se movement, and -particularly relates to a stace a:::)-oaratus movable in one linear direction capable of high accuracy positioning and h-Jch s-Deed movement, which can be especially favorably utilized in a microlithographic system.

io is In waf- er ste-nzers, the alignment of an exposure _f ield to the reticle being imased 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 durina the exposure secje--lce. This invention discloses an anmaratus to achieve -Drecise scanning mnotion 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 sta-e. 7- should also have high control bandwidth, which requires t-a-L the stage be a light, m,ovna oarts. Furz"1-4erT,,ore, L-he stace should be free f-rom excessive heat ceneration which might cause interferometer interfe-ence or mechanical chances that co-,n,-Dromses al- icnrr,en-- accuracy.

Commutator-less electromagnetic alignment apparatuses such as the ones disclosed in U.S. Pat. Nos. 4,506,20,,,-,500',205 and 4,507,597 are notL feasible because they structure with no is require the manufacture of large magnet and coil assernb-'L,-s that are not com-mercially ava--1abe. The weight o, the stage and the heat gene. rated also rendel- these designs inappropriate for h-;.ah accu"racv a-:, ol-:cat-ons.

An iT-,,,arovement over these com-mutatoriess apparatuses was disclosed in U.S. Pat. No. 4,952,858, which emmploys a con-jentional XY mechanically guided sub-stage to t"--- larce d--sniace-,-.ient motion -'n the niane, thereby -for larcre magnet and col asse-,,ib--, el mninatinc the need!-:es.

The electromagnetic means mounted on the sub-stage isolates the stage fronni mechanical disturbances. Nevertheless, the combined weight of the sub-stage and stage still results'in low control bandwidth and the heat cenerated by the electromagnetic elements supporting the stage is still substantial.

Even though current apparatus using commutated electromacnet-ic means is a significan-L_ improvement over nrior commutatorless ones, the problems o-,.- low control bandwidth- and inter-ference persist- Tn s an annarat-us, a sub-st-age is moved magnetically in one linear d-ect-cn and the commutated ele--tro,-,iaanet--;c means mounted on the sub-stace in turn moves the stace in the normal dil rectio-n. The sub-stage is heavy because it carries the magnet tracks to move the stage. Mo--eover, heat dissination on the stage compromilses interferometer accuracv.

U c h It 's a-,so well knowrn. to move a movable member w. - (stace) in one long linear direction (e.c. more than 10 cm.) by us na two o-f the 11 inea.r motors in -parallel where coi and magnet are cor,,ibi- ied. In this case, the stage is guided by some sort of a linear quiding me,-,Lbe-- and driven in one linear direction by a linear motor installed parallel to the guiding member. When driving the stace only -.c the -3 extent of extremelY small stroke, the cr based on the combination of several electromacnetic structure actuators, as disclosed in the 1Drior art ment--;lcned before, can be adooted. However, iin order to move the guJdeless stage to a long distance in one linear direction, a specially structured electromagnetic actuator as in the Qricr- arts becomes necessary, causing the size of the au-j)aratus to become larcrer, and as a result, problem of consuming, more electricity.

io weneratina a I t is anobject of the present invention to make i possible for a guidless stage to move in the direction of: a long linear motion usin-g.electrornagnetic force, and to r)rovide a licht we;ght aD-ja--,-atus in which low inertia and high resnonse are achieved.

Furthermore, it is an object of the present invention to Drovide a guidless stage apparatus using coT.-,,,erc-ialiv available recular linear motors as elec-lro-,,ac-7.,c=--c actuators f'or one linear direction motion.

Furthermore, it. is an object of the oresent nve--.it-:on to Drovide a guideless stage apparatus canable Of active and precise position control for small di-'sniace-.ne7,ts without any contact in the d-irec-L-lo--1 orthowonal to the lona iinear motion direction.

Furthe-rmore, it is an objeCt of' the present invention to -,Drovide a completely non-contact stage ar)r)araus by Providing a movable member (stawe body) to move in one linear direction and the second movable ne-,.-be-,t- to move sec-uientially in the same direction, constantly keeping a certain space in between, and providing the eleczromag--ier-c L orc:e (acton and reaction force) in the d-reczi-Jon 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 oreventing the positionilng and running accuracy fro-m 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 is an object of the present invention to -orovide a non-contact aiDpa--atus 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-con--ac-L stage body moxies in one linear direction.

1 -- - According to one aspect of the present invention there 20 is provided a stage apparatus having a movable stacre which is movably supported on a base, comprising, a drive device for drivinw- said movable stage, a balancing portion disposed outside said movable stage, and a non-co-±--act bearing which opposes said balancing portion to said base without 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 of said movable stage without any mechanical a As commutated contact with said base. specific feature of the invention linear 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 driving frame. Both motors drive in the same d'lrect-ion. 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 driv-Lng method for drJl.ving a movable stage which is movably supported on a base, compriis--:,ng, 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.

? S - t- the stage motion to the three By restricting specified degrees of freedom, the apparatus is simple. By using electromagnetic components that are commercialIv available, the aPparatus design is easily adaptable to changes in the size o-E the stawe. This high accuracy iDos-itioin.-:LnaapDaratus is ideally suited for use as a reticle scanne-- in a scanning exposure system by providing smooth and urec-ise scanning motion in one linear direction and ensuring accurate alianment by controlling small disniacement motion per-oendicular to the scanning direction and small yaw rotation in the plane.

Other aspects and features and advantaaes of the present invention will become more apparent upon a perusal of the following specification taken i in conji-,nct-on with the accompanying drawings'wherein similar characters oZE reference indicate similar elements in each of the several views, and in wh-ch:

1..11, -'s Fig. 1 is a schematic perspective view of apparatus accordance with the present invention.

Fia. 2 is a tor) iD!an view cla the arDparatus shown in i.

Fig. 3 is an end elevational view of L-he structure showrn, in F-Lg. 2 taken along line 3-31 in the dJ-ectJon of the arrows.

Fics. 4A is an enlarged perspective, nartilaily -.0 exr)loded, view showing -the carr-ier/.Lc:'oliower structure of Fig. i and e=loded Afrom the positioning guide F ig. 4B is an enlarged horizontal sectional view or a Dortion of the structure shown in Ficy. 5 taken along line 4B in the direction of the arrow.

Fig. 4C is an enla rged elevational sectional view of a portion of the structure shown in Fig. 2 taken along 1ine,=C in -the direction of the arrow but with the voice coil motor removed.

-;a. 5 is an elevational sectional view o' a iDortioP of the structure shown in Fig.. 2 taken along liline 5-5' in the d..rect- ion of' the arro-ws.

Fig. 6 is a block diagram schematically illustrating the sensing and control systems for controlling the -Dosition of the stace.

A-a. 7 is a plane view, similar to Fri w. 2, illustrating the preferred embodiment of the present L invention.

Fic. 8 is an elevational sectional the st-uctu--e shown in Fig. 7 taken along line 8-81 in the -10 d---ect'.on of the Fics.

s-im--1ar to er,ibod-i-,n,ent - arrows.

9 and 10 are much simplified views _Pias. 7 and 8 and illustrating still another of the -oresent invention.

M-i-le the present invention has applicability general!-,\, to electromagnetic alignment syste-ms, the prefer--ed embodiment involves a scanning apparatus for a reticle stace as illustrated in Fics. 16.

is 2 0 Re..L:err-ing now to the drawings, the iDosiLt-Jon--'Lng annaraus 10 of' the uresent invention includes a base structure 12 above wh-ich a reticle stace 14 is SuSnended and mo-jed as desired, a reticle stage position trackina laser interferometer system 15, a position sensor 13 and a position control system 16 olDerating from a CPU 16' (see' Fig. GY.- Aun elongate positioning guJde 17 is m ounted on base 12, and support brackets 18 (two brackets in the t " illustrated ernbodiment) are movably supported on the guide 17 such as by air bearings 20. The su-,--),Dort brackets 1-8 are connected to a driving assembly 22 in the for-m of a maanet-e tracil-1 asse-mbly or driving fra-ne for driving the rezicle stace -14 1'n the X direction and srnall yaw rozation.

The driving -Erame includes a pa..AIr of: parallel s-oaced auarz magnetic track ar-ms 24 and 26 which are connected toget-her to form an oDen rectangle by cross ar-ms 28 and 30. 1 n t he pre.':erred embod-ment the drivina frame 22 is- movabiv I - - 1 Supported on the base structure 12 such as by air bear-.lnzs 32 so that the frame is -free to move on- the base structure in a direction al, with the ongi-ud..i:-nal axis of the guide 17, the -Dr-Jnc-ir)al direction in which the scanning motion of the reticle stage is desired.

71 As used herei- "one or a "first direction" applies to movement of the -Erame 22 or the- reticle Stace- i'4 either forward or back in the X direction along a line aligned with the longitudinal axis of the guide 17.

-g- i 0 is Referring now to P-Ja-s. 1 and 5 to explain further in detail, the e'longate guiding member 17 in the X direction has front and rear gu_::_d-ing surfaces 17A and 17B which are almost iDe---iDendicula--- to the surface 12A of the base str-acture 12. The -front guiding surface i7A is against the --ectanFular driving frame 22 and c-udes the air bearing 20 which is fixed to the inner side o.E' the sunnort bracket 18. -zk support bracket 18 -'s mounted on each end of the upper surface of the arm 2, which is parallel to the guiding rb Further-ni nember 17 of the driving frame 22. ore, each support bracket 18 is 'Lo---,ned in a hook shape so as to st-raddle the guiding member 17 in the Y direction and with the free end against the rear cruiding surface 17B oJES the rear side of the guiding member 17. The air bearing 20' is -,."'-xed inside the free end oJ_f the support brackets!a and against the rear Suiding surface 17B. Therefore, each of the su-Dnort brackets 18 is constrained in its d-is.,Dlacemen- in the Y direction by the guiding member 17 and air bearings 20 and 201 and is able to move oniv in the X direction.

Now, accordJnw to this J-E--irs-t eribodment o' the nresent invention, the air bearings 32, which are fixed to the bottom surfaces of the 'Lour rectancular parts of the driving frame 22, make an air layer leav--'lng a constant ga-p (1 several im) between the pad surface and su-,cace 12A of the base structure!2. The driving -f-rame is buoyed up from the surface 12-2k and supported iDe---oend-Jcularly (in Z d-'.rect-on) by the air layer. It wil-1 be exD!a-ined in detail later, but in Fic. 1, the carrier/follower 010 shown positioned above the upper part of the ellongate arm 24 is z>os-t-icned lateraliv in the Y direction by air bearings 66P.

and 69B suuiDorted by a bracket 62 against oQooste surfaces 17A and 17B of guiding member 17 and vertically in the Z direction by air bearings 66 above the surface 12A of the base structure 12. Thus. the carrier/follower 60 is positioned so as not to contact any part of' the driv-.:-na- frame 22. Accordingly, the driving frame 22 moves only in one linear X direction, cruided above the base surfac2 12A and laterally by the guiding member!7.

Re-terring now to both Fig. 1 and Fig. 2,. the structure of the reticle stage 14 and the driving frame 22 will be explained. The retilcle stage 14 includes a main body!2 on which the reticle 44 is positioned above an opening 46. The reticle body 42 includes a pair of opposed si-des 42A and 425 and is positioned or suspended above the base structure 12 such as by air bearings 48. A plurality of interferometer mirrors 50 are provided on the main body 42 of the reticle stace 14 for oDeration with the laser nter,Oerometer position sensing system 15 (see Fig. 6) 'for L determining the exact position of the reticle stage which s fed to the posit-lon control system 16 in order to d rect the aDP--onr-ate drive signals for moving the reticle stage 14 as desired.

Primary movement o--':: the reticle stage 14 is accomulished with first elect romagnet ic drive assembly or means in the flor:n of separate drive assernblies 52A and 52B on each of the opposed sides -2A and 42B, resnectively The drive assemblies 52A and 529 include drive coils 54-A and 545.L=-iy.ed!' mounted on the reticle stacre i4 ac the sides y w2A and 425, resnectively, for cooperating with magnet- tracks 56.P and 562 on the macnet track arms 24 and 26, re-sDectively, of' the drive frame 22. While in the mreferred embodi-ment of the invention the magnet coils are mounted on the reticle stage and the magnets are mounted on the drive frame 22, the Dositions of these elements of the electromagnet ic drive assembly 52 could be reversed.

Here, the structure of the reticle s-ace 14 will be ex-Dla--"ned further in detail. As shown in Fig. 1, the stace body 42 is installed so that it is free to move in the Y the rectancrular space inside the driving frane 22. The air bearing 8 fixed under each of the four - the stage body 2 air corners o., makes an. extremeiv small gap between the pad sur-face and the base sl-lr--,':ace 12A, and buoys up and supports the entire stage i'r 1Erom the surface 12A. These air bearings 8 should iDre.-'rerably be preloaded types with a recess -for vacuum attraction to the surface 12A.

As shown in Fia. 2, a rectangle opening 46 in the J: the stage body 42 is -provided so that the center of L projected image of the pattern fo-med on the retilcle 44 can go through. In order for -the projected image via the rectangle openincr -6 to pass -through the projection optical system PL (See Fig. 5) which is installed below the rect-angle openinw, there is another oje-n-J--c 125 provided at t 'ne center part the base structure 1-2.

The reticle 4,1 s loaded' on the top surface of the stage body by clamping L- - - - 1 - mem.bers 42C which are protrusively placed at -four -joints around the rectangle opening 46, and clamDed bv the vacuum pressure.

Now, the interferometer mirror SOY, which s near the side 42'S of the stage bodv 42 near arm 26, has a vertical elongate surEace in t-l-,e X direction which lencth is so-,,tehv;a: longer than the movab3e stroke of the stace 14 in the X direction, and the laser beam LBY the Y-axis interferomeer is on the rej.'-:lect-na In Picr. 2, LBY the laser beam is bent at a right angle by the mirror i2D which is fixed on the side of the base structure 12.

Referring now to Fig. 3 as a pat-tJal cross-sectional dra,,-i-a of the 33' view in Fig. 2, the laser beam LSY w'-ich is incident on the reflecting surface oJE: the nter--:erometer mirror SOY is placed so as to be on t sam e niane as the bottom sjr.'ace (the surface where the pattern is formied') of the retlicle 44 which is mounted on the clamning member 2C.

Furthermore, in Fig. 3, the air bear-:ng 20 on the end side of the support brackets!8 against the quiding surface 1713 off the guiding memiDer 1-7 is is also sho,m.

RefEerring once again to Pigs. 1 and 2, the laser beam LBX1 from the X!-axis interferometer is incident and reflected on the interferometer mirror 5OXI, and the laser beam L3X2 from the X2-ax-'s -interferometer is incident and reflected on the inter".,L-e--omete-- mirror 5OX2. These two mirrors 50Xl and 5OX2 are structured as corner tube type mirrors, and even when t.n.e stage 1-4- is in yaw rotation, they always maintain the incident axis and reflecting axis o-E the lase-- bea-,-,s parallel within the XY -Dlane.

7u.-thez-,-p.ore, tn- block 12C in Fi. 2 is an optical block such as a -Drism, to orient the laser beams LBX1 and L5X2 to each o--," the mirrors SOXI and 5OX2, and is fixed to a part of the base structure 12. The corresponding block.E:or the L2Y laser beam, is not shown.

In Pig. 2, the distance BL in the Y djrectio:-- between each the center lines o-f the two laser beams LEXI and L5X2 is the length of the base line used to calculate the amounc yaw rotation. A-ccordnaiv, the value of' the d-i-.::-i^erence between the measured value AXI in the X direction cf: the X-L-axis and the measured value tX2 in the X d''-rect-Jon of the X2-axis interferomezer divided by the base line length EL is the approximate amount of vaw rotation in an extre-mely small rancre. Also, half the value of the sum of the LX! and LX2 represens the X coordinate position of the ent-Lre stage 1,. These -10 is calculations are done on the hich s-oeed dcital processor Z _In the position control system. 1-6 shown in F-:c7. 6.

F=E he --more, the center lines of each of the laser beams and LBX2 are set on the same surface w'-ere the patern is formed on the reticle =4.

The exz:ens-;;..on of the line C-X, wr,-ch is shown, in 2 and divides in half the sr)a--e between each of the center lines of laser beams LBX! and LEX2, and the extension of the laser beam LBY intersect within the same surface where the pattern is formed. And furthermore, the optical axis AX (See Figs. 1 and 5) also crosses at this intersection as shown in Fig. 1. in wig.

i, a slit shape illumination field ILS which includes the ootical axis AX is shown over the reticle 44, and the Dattern imace of the reticle 44 is scanned and exoosed onto the iDhoto-sensitive substrate via the iDrojection ontical system PL.

Furthermore, there are two rectangular block's 90A and 90B fixed on the side 12-k of tIne s--aae body 12 in FiSTS. 1 and 2. These blocks 90A and 90B are to receive the driving force in the Y direction from -he second electro-ma( I- Tne'ic actuator 70 wh_ich is mounted on the carrie--/.ollower 60- Details will be ex-jla-ined later.

O The driving coils 5,A and 54-B which are fixed on the both sides of the stage body 42 are formed -at -Darallel -to the XY nlane, and pass through the macnetic -."jux snace in the- slot which extends in the X d.Irection of: the macnetic track 56A and 56B without any contact. T'he asse-,.L-,!y 0-f the dr--1v.-;'.ng coil 5, and the magretic track- 56 used in tine uresent embodiment is a commercially easily accessible linear motor for general purnoses, and it could be either- with or without a com&,,iiutator.

--7ere, co7-,s-"dering the actual design, the mov--'lnc stroke of"' the reticle stage 14 is mostly determined by the size of' the reticle (the amount o= the time of scanningfor exposure and neede-,.; at the time of removal o_f the o-Dtcal system to change case t'-e -cresent embodiment, w',-n retcle is used, movement rec-uired at the amount o--1 movement reticle zrom, t:-ne the rel,--icle). In the a (15.24 crr.) the -o,,,-iLng-strck-e is about - 3 0 C.rr..

As mentloned be-fore, the dr--,'-jina frame 22 and t_ne -.0 -'s stage!4 are independently buoyed up and supported on the base-surface 12A, and at the same time, magnetic action and react ion- 'iE-orce---is applied to one another in the X direction oniv bv the linear motor 52. Because of that, the law of the conser-vat-io-1 of momentum. is seen between the dr-v-nc frame 22 and the stage Now, su::)nose tHe weight o= the entire re-cle stage 14 is about one -'Lil-E-th of the entire weight the frame 22 which includes tIne support b_rackets -1-8, then, the for.ward movement c- 30 cm o_f the stace 'n the X direction rakes X t,,e drivinw- --1wrame 22 move by 6 cm backwards the gravity o.E the apparatu_s an the base structure 12 s essentially fixed in L-he X t-ere is no movement of any heavy object.

Tn the Y dJ-ect-,on, There-fore, the chance in the location ofIE the center oF the in Y direction is also relative!-,,, The stage!4 can be moved in the X as t -)= described above, but the cojls 542) and the motors 52 w11 -Jnter.e-e each other (collide) in the Y dir-ection an X direction actuator. Therefore, the 60 and t - e second electromagnet ic actuator 70, which are the -Is- characteristic components of the present invention, urovided to control the stage 14 in the Y direction.

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

As shown in Fig. 1, the carrier/f ol lower 60 is movably installed in the Y direction via the hook like support bracket 62 which straddles over the guiding member m Furthermore as evident from Fig. 2, the carrier/follower 60 is placed above the arm 24, so as to io maintain a certain space between the stale 14 (the body 42) and to the arm 24, respectively. One end 60E of the carrier/f ol lower 60, is substantially protruding inward (toward the stage body 42) over the arm 21. Inside this is end part 60E is fixed a driving coil. 68 (same shape as the coil 54) which enters a slot space of the magnetic track SEA.

Furthermore, the bracket 62 supported air bearing 66A (See Figs. 2, 3, 4A and 5) against the. guiding surface 17A of the guiding member 17 is fixed in the space between the guiding member!7 of the carrier/ f cl lower 60 and the arm 2i. The air bearing 66 to buoy up and support the carrier/follower 60 on the base surface 12A is also Shown in Fig. 3.

The air bearing 66B apainst the guiding surface 17B of the guiding member 17 is also fixed to the free end of support bracket 62 on the other side of the hock from air bearing 66A with guiding member 17 therebetween.

Now, as evident from Fig. 5, the carrier/follower 60 is arranged so as to keep certain spaces with respect to both the magnetic track 56A and the stage body U in the Y and Z directions, respectively. Shown in Fig. 5 are the projection optical system PL and column rod CB to support the base structure 12 above the projection optical system is PL. Such an arrangement is typical for a projection aligner, and unnecessary shift of the center of the gravity of the structures above the base structure 12 would cause a iateral shift (mechanical distortion) between the colul-nn_n rod CS and the projection optical system PL, and thus result in a deflection of the image on the photosensitive substrate at the time of exposure. Hence, the merit of the device as in the present embodiment where the motion of the stale in does not shift the center of the gravity above the base structure 12 is substantial.

Furthermore referring now to Fig. 4A, the structure of the carrier/follower 60 will be explained. In Fig. 4A, the carrier/follower 60 is disassembled into two parts, 60A and 605, for the sake of facilitating one's understanding. As evident from Fig. 4A, the driving coil 68 to move the carrier/follcwer 60 itself in the X direction is fixed at the lower part of the end 60E of the carrier/follower 60. Furthermore, the air bearing 65C is p! ' aced against the base structure 12A on the bottom surface of the end GOE and helps to buoy up the carrier/follower So.

Hence the carrier/follower 60 is supported in the Z direction with the following three points, the two air bearings 66 and one air bearing 6SC, and is constrained in the Y direction for movement in the X direction by air bearings 66A and GGB. What is important in this structure is that the second electromagnetic actuator 70 is arranged back to back with the support bracket 62 so that when the actuator generates the driving force in the Y direction,_ reaction forces in the Y direction between the stage 14 and the carrier/follower 70 actively act upon the air bearings 66A and 663 which are fixed inside the support bracket 62. in other words, arranging the actuator 70 and the air bearings 66A, 66B on the line parallel to the y-axis in the 1 1 - i i 1 XY niane helDs -Drevent generating unwanted stress, which m-a-'nt deform the carrier/--:o--ilower 60 mechanically when the actuator 70' is in o- Deration. Converseiv, it means that it is iDossible -c reduce the weight ofF the ca-rie f _ -L r/follower - As evident from Figs. 2, 4A and CC described above, the nag.-iel--i-c traCk 56.P. in the arm, 24 of the driving frame 22 provides magnet-ic for the coil 54-1 on the stage body 2 side, and concurrently provides magnetic flux for the driving coil 68 for the carrier/f_ollower 60. As Lo-- the air bearings 66A, 66B and 66C, a vacuum pre-loaded ty-ie is Preferable, since the carrier/follower 60 is licht.

Besides the vacuum pre-loaded type, a magnetic pre-loade_d type is also acceptable.

is Next with re-Eerence to Pigs. 3, 45 and 5, the actuator mounted on the carrier/follower 60 will be exD!a-ned. A second electromagnetic drive asseribly i form of a voice coil motor 70 --'Is made.un c-lz a voice at-tached to the main body 42 of the.-et-icle stace 14 magnet 72 attached to the 90 to move stage 141 for small displacerments in the Y dilrection in plane of the travel of the stace 1,I- orthogonal to the direction long linear motion produced bv the driving assembly 22. The Dositions of the coil 74- and magnet second n the coil 74 and a t,- _ t he X 72 could be reversed. A schernatic s:ructure of. the vol-Ice coil motor (VCM1) 70 is as showrn in Figs. 3 and 5, and the detailed structure is shown in Fig. 45. Shown- in _Fig- 4EE is a cross-sectional view of the VCY, 70 sectioned at the horizontal niane with an arrow 4B in Fig. 5. in Fria 45, the magnets 72 of the VCM 70 are fixed onto the carr-;.er/-L:ollowe--yside.

And the coill of the VCY1 70 comnrises the coil body 74A and its sunnorting part 74E/ and the supporting oart 7,B is fixed to a connecting plate 92 (a plate vertical to the XY plane) which is rJcidly laid across the t,. ,.;o rectangular blocks 90A and 90B. A center line M oL the VCM 70 shows the direction of the driving 0 S the coil 7,, and when an electric current flows orce o L through the coil body 74A, the coil 74 displa-ces into either positive or negative movement in the Y d.-:.rection in accordance with the direction o--,': the current, and generates .i: a force correspondent to the amounc of the current Normally, in a commonly used VCM, a ring-like damper or bellows are provided between the coil andmagnet so as to keep the gap between the coil and magnet, but according to the =esent embodiment, that gaiD is kept by a follow-up motion o-",: the carrier/f ol lower 60, and therefore, such supporting elements as a damper or bellows are not necessa-,-v.

In the present embodiment, capacitance gap sensors !3k and 1-39 are urovided as a -Dosition-ing sensor 13 (see electrodes for ia. 6) as shown in Fig. 4B. in Fig.AB, car)ac-tance sensors are -Diaced so as to detect the chancre n the gaD in the X d'recto--i between the s-"de surlface o' the ---ec!--anc-LIar blocks 90A and 90B facing with each other 4n the X direction and the side surface of a case L 7 0 the VCM 70. Such a positioninc: sensor!3 can be placed anywhere as far as it can detect the ca..) chancre in the Y direction between the carrier/follower 60 and the stacre-!, (or the body 42). Furthermore, the type of the se.n-sor can be anv of a noncontact ty-pe such as Jnduct-Jve, ultrasonic, or air-micro svstem.

The case 701 in FJa. 5 is with the 60 in one, and ziaced (s Dat-.:ally) so as not to contact any member on the reticle stage!4 sidle. for the gap between the case 701 and the rectangular blocks 90A and 901 in the X direction (scanning dIrection), when A S 19- the gap on the sensor 13A side becomes wider, the gap on the sensor 1-3 B side becommes smaller.

Therefore, if the difference between the measured gap value by the sensor 13.14 -. 0 and the measured gap value by the sensor 13B is obtained by either digital operation or analog operation, and a direct ser-vo (feedback) control s. n ystem wl-ic controls the driving current of the drvr-a coil 68 for the carrier/-followe- 60 s designed usilnw a servo driving circuit which makes the gap difference zero, then the carrier/ fo 11 ower 60 will automatically perform a follow-up movement in the X d.irection always keeping a certain snace to the stage body 42. or, it is also possible to desian an indirect servo control system wInich controls an electric current flow to the driving coil 68, with the operation of r)os--ion control system 16 in Fig. 6 using the measured cap 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 i3A an-d 13B differentially.

in the VCY1 70 as described in F--',c:. -1-3, the gap between the coil body 74A and L-he magnet 7 2 i:n -- h e X direction (non-energizinS direction) is in- actuality about 2 3 mm. Therefore, a follow-up accuracy of the carrier/follower 60 with resiDect to the stage body 42 would be accentable A-t around,5 - 1 mm,.

This accuracy denen,-5s on how much of the yaw rotation of the stage body is a-,!owed, and also de-Dends on the length of the line J-1 the KX direction (enerc7iz-ing direction) of the coil- body TCA 02E the VCM 70. 1Furthermore, the degree of the accuracy this can be substantially lower than the nrec-ise Dositionina accuracy for the stage body 2 -,sing an L interferometer (e.c., +0.03 pm supposing the resolution Of the interferometer is 0.01 pm.) This means that the servo system -for a 'Lollower can be designed fairly simply, and the amount off cost to install the follower control system would be s-mall. Furthermore, the c:

line KX in, Fic- - 43 1:1 s set so as to co throuch the cente-l- of the gravJtv o1E the ent-ire stage 1-4 on the XY)lane, and each of centers O-LE the pair 0. the air bearing 66A and 66-Z provided inside the suDr)ort brackets 62 shown, in Fig. 1 is also positioned on the line Y,X in the XY plane.

Shown in 4C is a cross -sect ional drawing o.L:: the io part whch includes the guliding member i7, the carrier/fol lower 60, and the magnetic track 56A sectioned from the direction of the arrow 4C in Fig. 2. The arm 4 storing the magnetic track 56A is buoyed up and supported on the base surface 12A by the air bearing-32, and the carr-----/-J-ollower 60 is buoyed up and sunported on the base surface -12A by the air bearing 66. At this time, the height the air bearing 48 at the bottom surface o.LO the stage body 42 (see Fics. 3 or 5) and the he-9',n--L of' the air be-arinw 32 are determined so as to place the drving coil A on t - --- stace body 42 side- keeping a 2 3 mm. gap in Z direction in the slot snace clE the magnetic track SIGA.

Each of the spaces between the ca-rier/.;:olloAer 60 and L-he arm 24 in the Z and Y directions hardly changes because they are both guided by the common cudJng mernber 17 and the base sur'L'ace 12A. Further-more, even i..E there is a d----'Lerence in the height in the Z di-rection between the part on the base surface 12P. where the air bearing 32 at the bottom surface of the driving -frame 22 (ar-m 2,-) is a-Li-ded a-d bearing 8 quided, as w the nart on the base sur-LEace 12A where the air at the bottom surface Of the stage body is long as the d_j.:'-fe--e,-ice is precisely constant thin the moving stroke, the wan in the Z direction between the magnetic track 56A and the driving Coil 5-1-A is also preserved constant- Furthermore, since the driving coil 6s for the carr-:,er/-Aol-lower 60 is or-'.5-nally L:ixed to the carrier/fEollower 60, it- is arranged, maintaining a certain Sap of 2 - 3 mm above and below in the slot space of the magnetic track SOGA. An.d L-he driving coil- 68 hardly sh-i--"'-ts in the Y direction with resnect to the magnetic track 55A.

Cables 82 (see Fa. 2) are 1Drovided for directina the signals to the drive coils 54A and 5,B on stage 14, the voice coil motor coil 74 and the carrier/ji-'ol lower drive coil 68, and these cables 82 are mounted on the -7foll carrier L ower 60 and guide 17 thereby eliminating drag on the reticle stage 14. The voice coil motor 70 acts as a bu--1EzLer by denying transmission external mechanical disturbances to L-he stage 14.

Tberefore, referring now to Pigs. 2 and 4A, the cable issues will be described further in detail. As shown lin Pig. 2, a connector 80 which connects wires ol tIhe electric system and tubes of the air pressure and the vacuum system (here ina.E t er called,cables") is mounted on the base szructure 12 on one end of the guidina member 17. The connector 80 connects a cable 81 from the external control system (includ-Lna- the control system o-.c air iDressu--e and vacuum system besides the electric systen, control system showr in Fig. 6) to a flexible cable 82. The cable 82 is fur-he- connected to the end 'Dart 60E of the carr-er/.jEol lower 60, and electric system wires and the air pressure and the vacuum system tubes necessary for the stage 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 apbears as moment in unexpected direction between the carri er/f ol lower 60 and the stage body 2. In othe"-- words, the tension of the cable 82 gives the carrier/,fLol lower 60 a _force to -rotate the 9--,iding sur":ace o-E the g-i-idina member 17 or the base surface 12A, and the tension o-z'' the cable 83 gives a force to the carri, er/-.ol lower 60 and the stage body to rotate relatively.

one o.':: these moments, the const-ituent wh_ich sh_.,ts the 60, is not problematic, but t_he one which shi-fts the stage body in X, Y, or 0 direction (yaw rotation direction) could affect the alignment or overlay accuracy. As for in X and e directions, shifts can be ' correct-id by'aconsecutive drive by the two linear motors (54A,56A,543,56B), and as for in the Y direct-on, the shift can be corrected by the -VCM 70. In the present embodiment, since the weight of' the entire stage 14 can be reduced subs t antially, the response of the motion o-E: L-he stage 14 by VCM, 70 in the Y direction and the response by the linear motor in X and 9 directions will be extremely hcih in cooneration with the completely non-contact gulldlless structure. Furthermore, even when a micro vibration micron o-r-de-) is generated in the carrier/ fol lower 60 and it is transferred to the stage 14 via -he cable 83, the 1. - I_ vibration (.-':rom several Hz to tens of Ez) can be canceled by the above mentioned hich response.

Now, Fia. 41. shows how each o=" the cables is d-stribu----d at the 60. -Each o_f the drivinc si( L - gnals to the driving coil 54A, 545 for the stace body 42 and the driving coil 74 o_f the VCM 70 and the detection signal from the nosition sens.or 13 (r_he gap sensors 13A, 133) go through the electric -s,,isCe-,i wire 82k :E r OM t ' me connector 80. 1Phe pressure cas and the vacuum 'to each o the air bearings 48 and 66 co through the pneumatic 1 system tube 821 from the connector 80. On the driving scna-l to the driving coil 54-A L-he electric system wire 83A which the other hand, and 5,B goes is connected to the stawe body 2, and the r)--essur.:ozed cas bearing 48 and the vacuum -Eor the clamping t',-..--oucl. the r)neumatic system hoses 835.

W for the air member 42C 90 Furthermore, it is preferable to have a separate line or the uneumatc svste-,r, for the air bearings 20, 201 and 2 of the driving frame 22, inde:Dendent of the one showrn in -, 0 F a. 2. Also, as shoym 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 mom(nt by the tension 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.

Referring now to Figs. i, 2 and 6, the positioning of the reticle stace 1,11 is accom-iiishled f:-st kn-ow-ng its existing position utilizing the laser interferometer system co-'!s 5,A. and 5-9 for driving the stage!A direction. A difference in the resulting o-Dnosite sides 2A and d.!-2B of the reticle nroduce small yaw rotation of' the reticle n the X drive to 'the stace 14- will stacre 14. A2n a:DnroiD---a-ke drive signal to the voice coil 72 c-' voice c01.11 motor 70 nroduces small displace-ments of the reticle stace 14.1n the Y direction.

As the Dosition of thle reticle staze 14 chances, a drive signal is sent to the carr.er/.Lcollo,,e.- coil 68 causncr the carrJ er/.ocl lower 60 to follow the ---et-icle 14. Resulting reaction forces to the annlied drive tEorces will move the magnetic track asser,-Lbly or drive -frame 22 in a direction opposite to the movement o; the reticle stage 14 to substantially maintain is L J_ I the center of gravity Of the apparatus will be appreciated that the counter-weight or reaction movement of the maSnetic track asseT.bly 22 need not be -Included in the apparatus in which case the magnetic L-rack asserl,,-)!y 22 could be fixedly mounted on the base 12.

As described above, in order to control the szage system according to the iDres ent eribod-ime---it, a control system as shown. in- FJcr. 6 is installed. ':---.-is controlsvstem in -Fig. 6 will be f:urther e=. lained in detail here. X1 driving coil and X2 driving coil composed as the driv'ing C0-4-1s 54A and 543 of two linear motors respectively, and Y driving coil composed as the driving coil 72 of the VCM O are -olacedin the reticle stage 14, and the driving coil 68 is placed in the carrier/follower 60. Each of these driving coils is driven in resDonse to the driving signals SXI, 5X2, SY1, and SAX, resDectively, from the nosition control system 16. The laser interferometer system which measures the coordinates position of the stace 14 cormprises the Y axis Lnter-Lo'ero-nete-- which sends/recellves th-e beam,.SY, t-e XI axIs in'"er"erometer which sends/receives the beam L5Xl, and the X2 axis interferometer which sends/receives the beam LEX2, and they send 1Dos.:.tion n-lo-mat-0'-- for ea-h o= the directions of the axes, iFY, k_ - - L !FX1, IFX2 to the position control system 16. The position control system 16 sends two driving signals SXT and SX2 to the dr-Jv---a coils 54A and 5J13 so that the difference between the -in.-':::o---,nat-ion i-FX1 and!FX2 in the X direction will become a -Dreset value, or in other words, the yaw rotation of the reticle stage 14- is maintained at the sz)ec--', fied amount. Thus, the yaw rotation (in 6 d--',-ec!---ion) positioning by the beams L5X! and L3X2, X! axis and X2 axis inter-ferometers, the position control system 16, and the driving signals SX1 and 5X2 is constantly beina is conducted, once the reticle 44 is alicned on the 42, needless to mention the time o-IL:.the exposure.

Furthermore, the control system 16, which obtained the cur-rent coordinates position of the sta( e 14 in the X direction from the average of the sum of position i n nation IFX1 and!FX2 in the X direction, sends the driving sJanals SX1, SX2 to the dr4;_v-'nc coils 54A and 54-E, respectively, based on L-he various commands from the Host CPU 161 and the in-L-o---,nat-ion 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 systen 16 controls the two driving coils 54A and 54-B to give the same or slightly different forces as needed.

Furthermore, the position information. IFY from the Y ax-ls interferometer is also sent to the control system 16, and the control system 16 sends an optimum driving signal SAX to the driving coil 68 of the carr-er/-f ol lower 60. A-that time, the control system 16 receives the detection sianal S d from the position sensor 13 which measures the sDace between the reticle stage 14 and -the carrier/flol_ lower 60 in the X direction, and sends a necessa--y signal SAX to make the sic-nal S;,d into the preset value 1-1-s mentioned before, the follow-ur) accuracy for the carrier/follower 60 is not so strct that the detection s--:lcnal 5 >, of: the control system 1-6 does not have to be evaluated strictly either. For exam-le, when controll-Ing the motion by reading the position inforri-iiation T-FY,!FXl, I-FX2 every imsecond from each of the interferometers, the high speed processor in the control system 16 samr)les the current oJE 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 stage body a certain point, the signal SLX in ProDortion to the deviation can be sent to the driving coil- 68. Furthermore as mentioned before, i.-.- is also acceDtable to install a control system 95 which directly servo controls the driving Coil 68, and directly controls the foliowur) motion of the carrier/follower 60 without coJng through the position control system 16.

Since the moving stage system as showmn 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 of the base reference surface 12A or friction between comr)onents. One simnle method is to use weak bumpers (not shown) to 'orevent excessive travel of the drive asserrtbly 22. 7_---nother simple method is to turn off- the air to one or more of the air bearlinas (32,20) used to a-c-.ide the drive assembly 22 when the drive assembly reaches close to the end of the stroke. The air bearing(s) can be turned on when the drive besins to move back in the o-inos-te direction.

More -Drecise methods reauire monitoring the position of the drive assembly by a measuring means (not shown) and a,..D-Dly--'lng a driving force to restore and maintain the correct position. The accuracy of the measu--.-:.ng means need not be precise, but on the order of o.-, to i.0 mm. The driving force can be obtained by using another linear motor (not shown) attached to the drive asse-mbly 22, or another motor that is counled to the drive asse-mbIly.

660 of inally, the one or more air bearings (66,66', the carrier/follower 60 can be turned off to act as a brake during idle periods of the stage 42. if the coil 68 of the carr lower 60 is energized with the carr-4er/Lool lower in the braked condition the drive assembly will be driven and accelerated.

Thus, the nos-i:-t--'on control system is monitors the location of the drive assembly 22. When the d-rive assembly dri-fts out of position, the drive ly is repositioned with suff 1 assemb - -,--lic-:ent accuracy by intermittently usina the co-J1 68 the carrier/fol lower 22.

in the embodiment of the present inven Jon, the -,0 dr-v-ina frame 22 which functions as a counter we--ght is installed in order to prevent the center o_f the gravity of:

the entire system from shifting, and was made to move in.

-5site - cff--e'ction from the stage body 42. However, the opp 1 when the structures in Figs. 1 are a=lied to a system is where the shift of the center =E the gravity is not a major DrODlem, it is also acceptable to -L;:ix th.e driving frame 22 on the base structure 12 tocTether. Ln that case, except p for the problem regarding the center of the aravity, some o the e----cec--s and function can be anDlied wth-ou!-- any Cnal,Ces.

This -Invention r=vides a stage wInich can be used for high accuracy position and motion control in three degrees = J:

c- freedom in one plane: (I) long linear motion; (2) short linear motion perpendicular to the long linear motion-; and (3) small va.4 rotation. The stage is isolated fronn mech.anical dsturbances of surrounding structures by utilizing electro-magnetic -forces as the stage driver.

Bv using a structure for this guideless stage, a Mcn control bandwidth is attained.

These two factors con!--r-bute to achieve the smooth and accurate operatilon c- Descrjot--'on--of the Preferred E-mbodiment Bearing in mind the description of the embodiment illustrate,-' in Figs. 16, the preferred embodmen of the nresent invention is illustrated in Figs. 7 and 8 wherein the last two diwits of the numbered elements are similar to the corresponding two digit numbered elements in Figs. 1-5. Tn Figs. 7 and 8, differing from the previous first

L - - is embodiment, the driving frame which functions as a counter weight is removed, and eac.t- of the magnet- tracks ISGA and i56B of the two linear motors is rigidly mounted onto the base structure 112. T - lie 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 1129 is formed in the base structure 112, and the stage body 142 is arranged so as to st-raddle the opening part 112B in the Y direction. There are 'Lour pre-loaded air bearings 148 fixed on the bottom surface at both ends of the stage body 142 in the Y direction, and they buoy up and sumDort the stage body 142 against the base surface Furthermore, according to the present e-,,,bo"-j-Jment, the reticle 144 is clamped and supported on L-he reticle chuck Plate 143 which is separately placed on the stace body 142.

The st-raight mirror 150Y for the Y axis laser interferometer and two corner mirrors 150Xl, i5OX2 for the X axis laser inter-ferometer are mounted on the reticle chuck niate 1431. The dr-;.v,:.ng coils 154A and are horizontally fixed at- the both ends of the stage body 142 in the Y direction with resiDect to the magnetic tracks 156A and 1SCES, and due to the control subsystem nreviously described, make the stage body 142 run stra-al-it in the X d-recl----4on and yaw only to an extremely small amount.

A.s evident from, Fig. 8, the magnetic track 1565 O' the right side of the linear motor and the magnetic track 156A of the left side of the linear motor are arranced 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 _Js, as shown in Fig. 7, elevated by a certain amount with a block member 155 against the base surface 112A. And the carr --:L er/fol lower 160 where the VCM1 is fxed is arranged in the space belo-w the elevated magnetic track 1567-- The carrier/zoollower i60 is buoyed up and supported by the pre-loaded air bearings 166 (at, 2 points) on the base surface 112A, of the base structure 112 which is one - '-i-urther-more, two Dre-loaded air bearings 16, level 16we against the vertical guiding surface 117A of the straight is guiding r-.,emDer 117, which is mounted onto the base structure 112, are fixed on the side sur-face of the carrier/follower 160. This carrier/Afollower 160 is different from the one in FJa. 4A according to the previous err,bodiment, and the driving coil i68 (Fig. 7) for the ':cllowi-=r 160 is fixed horizontally to the part carr-ie--/which extends vertically from the bottom cz the carrier/ -fol lower 160, and nositioned in the masnetic flux slot of the magnetic track 1 56A without any contact. The carrier/follower 160 is ar-ranced so as not to contact iDart of the maa--ie--c track 1-56A within the range of the movin..a stroke, and has the VCM 170 which -jositions the stage body 142 'orec,:sely in the Y direction.

Furthermore, in Fig. 7, the air bear-Lng 166 which buoys up and supports L-he ca--rier/-L,olic)wer 150 is nrovided under the VCM 170. The followup motion to the stage body In i42 of the carrier/follower 160 is also done based on detection sicnal from the DositJon sensor 13 as in the previous embodiment.

-, C) In the second embodiment structured as above, there is an inconvenience where the center of the gravity of the entire system shifts in accordance with the shift of the stage body 142 in the X direction, since there is substantially no member which functions as a counter weic ht. It is, however, possible to position the stage body 142 precisely in the Y direction with non-contact electro-magnetic force by the VCM 170 by way of fo!10w-4-cthe stage body 142 without any contact -LlsinS the carrier/--,ollower!60. Furthermore, since the two linear motors are arranged with a difference in the level in the Z direction bet-ween them, there is a merit where the sum cf 1 the force moment generated by each of the the vectors OL linear motors can be minimized at the center of the gravity of the entire reticle st age because the force moment of each of the linear motors substantially cancels with the other.

Furthermore, since an elongated axis of action (the line KX in Fig. 113) of' the VCM.170 is arranced so as to -:)ass tl--i--ough the center of the crav.-l-ty of the entire structure of -the stage not only on the XY plane but also in L-he Z direction, it is more difficult for the driving force of the VCM 170 to give urnnecessarry moment to the stage body i-2. Furthermore, since the method of connecting the cables 82, 83 via the carrier/f ol lower 160 can be applied in the same manner as in the first em-bodiment, the problem rec:ard-Jn5 the cables in the completely non-contact Suideless stage is also improved.

The same 9,j-Jdeless principle can be e-,,,nloved in another embodiment. For example, in schermatic Figs. 9 and 10, th.e stage 242, s-a-jr)orted on a bases 212, is driven in the long X direction by a single moving coil 254 moving within a single magnetic track 256. The maane-.-ic track is rigidly attached to the base 212. The center of the coil is located close to the cent-er of gravity of the stage 242.

To move the stage in the Y direction, a pair of VC>M's (274A,27,-B,27 2A,2725) are energized to provide an acceleration force in the Y direction. To control yaw, the coils 274A and 274B are energized differentially 'under control of the electronics subsystem,. The vCM magnets (272A,272B) are attached to a ca--rier/ fol lower stage 260.

The carr-L lower stage is guided and driven like the -,o f;rs- embodiment previousiv described.

This alternative embodiment can be utilized ifor a waf-er 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 of gravity of the stage 242 passing through the coil 254 and track 256, a compensating opening in the stage 242 can be provided on -the opposite side c-E the coil 254 and track 256 trom the reticle.

Merits gained from each of the e-.,-Lbod-ime.-its can De roughly liste_ as follows.

the carrier/fol lower design elimina-es the problem, of cable drag for the stage since the cables connected to the stage follow the stage via the carrier/ fol lower. Cables connecting the carrier/follower_ to external devices will have a certain amount of dracr, but the stace is free from such disturbances since there is-no direct connection to /.:ollowe- which acts as a buffer by de,--yJng the t.he carrier transmission of mechanical disturbances to the stage.

Furthermore, the counter- wei, ght. design preserves the location c.;-: the center of: gravity of the stage system duri-g an-,., stace motion in the long stroke direction by using the conservation of momentum iDrincJnle. This apparatus essentially eliminates any reaction forces To nreser-ve accuracy, i 0 between the stage system and the base structure on which the stage system is mounted, thereby hah acceleration while minimizing vibrational e.l.,:::ects on the system.

In addition, because the stacre is des-'LS--ied -for limited motion in the three degrees ofE 'Lreedo-,-,i as described, the stage is substantially simpler than those which are designed for 'Lull 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 comnonents which become increasingly difficult to manufacture as the size and stroke of the stage iIncreases, 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 VCM1s.

While -the nresent invention has been described in terms of the preferred embodiment, the invention can take many different forms and is only limited by th-e- scone of the following claims.

33

Claims (24)

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

2. An exposure apparatus according to Claim 1, wherein said first drive device has a first portion to be connected to said mask 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 second portion comprises a magnet member.

0

5. An exposure apparatus according to Claim 2, 3 or 4, wherein the movements of said mask stage and said balancing 34 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 mask stage is movable over a surface of said base structure via a bearing.

8. A-n exposure apparatus according to Claim 7, wherein said bearing is a non-contact bearing which opposes said mask stage to said base structure without any contact therebetween.

9. An exposure apparatus according to any one of the preceding claims, further comprising a position detection device which detects a position of said mask stage.

10. An exposure apparatus according to Claim 9, wherein said position detection device comprises a reflective surface fixed to said mask stage.

11. An exposure apparatus accord-ing to Claim 10, wherein said reflective surface is a corner-cube type mirror.

12. An exposure apparatus according to Claim 9, 10 or 11 wherein said position detection device detects a position of said mask stage with regard to said scanning direction during the movement of mask said stage.

13. An exposure apparatus according to Claims 9, 10 or 11, wherein said position detection device detects a position of said mask stage with regard to a direction which is different from said scanning direction during the movement of said mask stage.

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

15. An exposure apparatus according to Claim 14, wherein said -centrol. _system is connected to said first drive de.ice.

16. An exposure apparatus according to any one of the preceding claims, further comprising a second drive device which moves said mask stage in a direction which is different from said scanning direction.

17. 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 J obj ect.

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

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

no

20. An exposure appa--atus according to Claim 8, wherein 36 said non-contact bearing is an air bearing.

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

22. An exposure apparatus according to any one of the preceding claims, wherein said balancing portion is of a 10 rectangular shape.

23. An exp osure apparatus according to Claim 9, 10, 11; 12, 13 or 14, wherein said position detection device comprises an interferometer system.

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