GB2325566A

GB2325566A - Electromagnetic scanning and alignment apparatus

Info

Publication number: GB2325566A
Application number: GB9817494A
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: 1998-11-25
Anticipated expiration: 2015-06-21
Also published as: GB2325565B; GB9825844D0; KR100281858B1; GB2329516B; GB9817493D0; GB2325565A; KR100281860B1; HK1035431A1; JPH0863231A; JP3804785B2; GB2329517B; JP2007242034A; GB2290658A; HK1025840A1; GB2329520B; KR100281859B1; HK1025842A1; GB2329521A; GB2329518B; HK1026766A1

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 positioning and motion control using one or more linear commutated motors to move a guideless stage 14 in one long linear direction and a small yaw rotation in plane. A carrier/follower 60 holding a single voice coil motor (VCM) 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. One element of the linear commutated motor is mounted upon a freely suspended 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 laser interfrometry system LBX1, LBX2, LBY, 50X1, 50X2, 50Y detects the exact position and orientation of the stage.

Description

2325566 ELECTROMAGNETIC ALIGNMENT AND SCANNING APPARATUS The Dresent

invention relates to a movable stage apparatus capable of precise movement, and particularly relates to a stage apparatus movable in one linear direction capable of high accuracy positioning and high sneed movement, which can be especially.-:avorably utilized in a microlithographic system.

in wafer steppers, the alignment of an exposure f iel to the reticle being imaged affects the success of the circuit of that fielE. In a scanning exposure system, the ret-ilcle and wafer are moved simultaneously and scanned across one another durina the exiDosure secuence. This inventior discloses an ar),Daratus to achieve precise for such a system.

scanning motion I To attain high accuracy, the stage should be isolated from mechanical disturbances. This is achieved by employing electrcmagnetic forces to position and move the stage. It should also have high contrcl bandwidth, which reauires tha-L the stage be a light, structure with no moving parts. Further-more, the stage should be free from excessive heat generation which might cause interferometer interference or mechanical changes that com-promises alignment accuracy.

Commutatoriess electromagnetic alignment apparatuses such as the ones disclosed in,U.S. Pat. Nos. 4,506,204, - feasible because they ,506,205 and 4,507,S97 are =- - d require the manufacture of large magnet and coil assemblies that are not commercially available. The weight of the stage and the heat generated also render these designs inappropriate for high accu'racy applications.

An improvement over these commutatorless apparatuses was disclosed in U.S. Pat. No.,952,858, which employs a conventional XY mechanically guided sub-stage to provide the large displacement motion in the plane, thereby eliminating the need for large magnet and coil assernblies. The electromagnet ic means mounted on the sub-stage isolates the stage from mechanical disturbances. Nevertheless, the combined weight of the substace and stage still results in low control bandwidth and the heat generated by the electromagnetic elements suz)nortno the stage is still substantial.

Even though current apparatus using commutated electromagnetic means is a significant improvement over prior commutatorless ones, the nroblems of low control bandwidth and interferometer interference iDersist. In such an apparatus, a sub-stage is moved magnetically in one linear direction and the commutated electromagnetic means mounted on the sub-stage in turn moves the stage in the normal direction. The sub-stage is heavy because it carries the magnet tracks to move the stage. Moreover, heat dissipation on the stage compromises interferometer accuracy.

it is also well known to move a movable member (stage) in one long linear direction (e.g. more than 10 cm) by using two of the linear motors in parallel where coil and magnet are combined. In this case, the stage is guided by some sort of a linear guiding member and driven. in one linear direction.by a linear motor installed parallel to the guiding member. When dr-'Lv-ing the stage only to the extent of extremely small stroke, the auidless structure based on the combination of several electromagnetic actuators, as disclosed in the prior art mentioned before, can be adopted. However, in order to move the guideless stage to a long distance in one linear direction, a specially structured electromagnetic actuator as in the prior arts becomes necessary, causing the size of the aur:)aratus to become larger, and as a result, generating a problem of consuming more electricity.

-, 0 2 S 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 using electromagnetic force, and to provide a light weight apparatus -Jr. which low inertia and high re sponse are achieved. invention Furthermore, it is an object of the present I to provide a g-aidless stage apparatus using com-mercially available reaular 1near motors as elec-roma=_etc f'or one 14 actuators near direction motion.

invention Furthermore, it is an object of the present to provide a guideless stage apparatus capable of active and precise position control for small dis- olacements without any contact in the direction orthogonal to the long 'inear motion direction.

Furthermore, it is an object of the present invention to provide a completely non-contact stage apparat-us by r)rovidinq a movable member (stage body) to move in one linear direction and the second movable member to move sequentially in the same direction, constantly keeping a certain space in between, and providing the electromagnetic force (action and reaction force) in the direction 4 orthogonal to the linear direction between this second moval:-le member and the stage body.

Furthermore, it is an object of the present invention to provide a noncontact stage apparatus capable of preventing the positioning and running accuracy from deteriorating by 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 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 moves in one linear direction.

According to one aspect of the present invention there is provided 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 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.

As a specific feature of the invention linear 3 commutated motors can be located on opposite sides of the stage and each commutated motor includes a coil member and k _ a magnetic member one of which is mounted on one oil' the opposed sides of the stage and the other or which is mounted or. the driving frame. Both motors drive in the same direction. By driving the motors slightly different amounts small yaw rotation of the stage is produced.

In accordance with another aspect of the present invention there is provided a scanning exposure method to transfer a pattern onto an object, comprising moving a stage in a scanning direction, the stage being movably supported by a base, moving a balancing portion in the scanning direction responsive to the movement of said stage, said balancing porting being movably supported by the base and exposing said pattern onto the object while said stage is moved in the scanning direction.

is 3y restricting the stage motion to the three specified degrees of freedom, the apparatus is simple. By using electromagnet ic components that are commercially available, the apparatus design is easily adaptable to changes in the size of the stage. This high accuracy positioning apparatus is idea'Iy suited for use as a reticle scanner in a scanning exposure system by providing smooth and precise scanning motion in one linear direction and ensuring accurate alignment by controlling small displacement motion perpendicular to the scanning direction and small yaw rotation in the plane. other aspects and features and advantages of the present invention will become more anoarent unon a Derusal of the following specification taker. in conjunction with the accompanying drawings wherein similar characters of reference indicate similar elements in each of the several views, and in which:

1 11. r,.1 3.

i 0 2 C Fig. I is a schematic perspective view of apparatus in accordance with the present invention.

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

Fig. 3 is an end ele-vational view of the structure shown in Fig. 2 taken aloncr line 3-31 in the (JLrection of the arrows.

Fig. 4A is an enlarged perspective, partiially exploded, view showing the carrier/follower structure of Fig. 1 and exploded from the positioning guide.

Fig. 4B is an enlarged horizontal sectional view of a T)OrtL_JOn Of the structure shown in Fig. 5 taken along line 4B in the direction of the arrow.

Fig. 4C is an enlarged elevational sect:-ional view of a portion of the structure shown in Fig. 2 taken along line 4C in the direction of the arrow but with the voice coil motor removed.

Fig. 5 is an elevational sectional view of a portion of the structure shown in Fig. 2 taken along line 5-51 in the direction of the arrows.

Fig. 6 is a block diagram schematically illustrating the sensing and control systems for controlling the position of the stage.

Fig. 7 is a plane view, similar to Fig. 2, illustrating the preferred embodiment of the present nve-nt ion.

Fig. a is an elevational sectional view of the structure shown in Fic. 7 taken along line B-81 in the direction of the arrows.

Figs. 9 and 10 are much simplified schematic views similar to Figs. 7 and 8 and illustrating still another emhod-iment of the present invention.

i 0 is while the present invention has applicability generally to electromagnetic alignment systems, the preferred embodiment involves a scanning apparatus for reticle s-age as illustrated in Figs. 1-G.

Referring now to the drawings, the positioning apparaLus 10 of the presen invention includes a base structure 12 above which a reticle stage 14 is suspended and moved as desired, a reticle stage position tracking laser interferometer system 15, a position sensor!3 and a position control system 16 operating from a CPU 161 (see Fig. 6).

P-n elongate positioning guide 17 is mounted on the base!2, and support brackets 18 (two brackets in the illustrated embodiment) are movably supported on the guide 17 such as by air bearings 20. The suDT)ort brackets!G are connected to a driving assembly 22 in the form of a magnetic track assembly or driving frame for driving the reticle stacre 1, in the X direction and small yaw rotation. The drviing frame includes a pair of parallel spaced a-Dart magnetic track arms 24 and 26 which are connected together L-o form an open rectangle by cross arms 28 and 30. n the preferred embodiment the driving frame 22 is movably supported on the base structure 12 such as by air bearings 32 so that the frame is free to move on'the base struct-ure in a direction aligned with the longitudinal axis of the guide 17, the r>rincipal direction in which the scanning motion of the reticle stage is desired. As used here-In "one direct:ionll or a "first direction" az)olies to movement of the frame 22 or the reticle stage 14 either forward or back in the X direction along a line aligned with the longitudinal axis of: the guide 17.

-I Referring now to Figs. 1 and 5 to explain further in detail, the e longat:e Suiding member 17 in the X direction has front and rear guiding surfaces 17A and 17B which are almost perpendicular to the surface 12A of the base structure 12. The front guiding surface 17A is against the rectangular driving frame 22 and g-uides the air bearing 20 which is fixed t the inner side of the support bracker-!8. P. support bracket iS is mounted on each end of the upper surface of the arm. 2, which is parallel to the guiding io member 17 of the driving frame 22- Furthermore, each support bracket --,8 is formed in a hook shape so as to st raddle the auidin(: member 17 in the Y direction and with the free end against the rear guiding surface 17B o-LE the rear side of the guiding member 17. The air bearing 201 is is fixed inside the free end of the suor)or- brackets 18 and against the rear guiding surface 17B. There-fore, (ach of the support brackets 18 is constrained in its displacement in the Y direction by the guiding member 17 and air bearin=s 20 and 201 and is able to move only in the X direction.

Now, according to L-his first embodiment of the present invention, the air bearings 32, which are fixed to the bottom surfaces of the four rectanaular parts of the driving frame 22, make an air layer leaving a constant gap (1 several um) between the pad surface and the surface 12.A of the base structure 112. The drivinc: frame is buoyed up =om the surface 12-k and supported perpendicularly (in Z direction) by the air layer. It will be exolained in detail- later, but in 1, the carr ier/f cl lower 60 shown positioned above the upper part of the elongate arm 24 is positioned laterally in the Y direction by air bearings 66-k and 663 supported by a bracket 62 against opposite surfaces i7A and 17B of guiding member 17 and vertically in the Z is 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 driving -Frame 22. Accordingly, the driving frame 22 moves only in one linear X direction, guided above the base surfacEt 12A and laterally by the 9-uiding member 17.

Ref:erring now to both Fig. I and Fig. 2, the structure of the reticle stage 14 and the driving frame 22 will be explained. The reticle stage 14 includes a main body 42 on which the reticle 44 is positioned above an opening 46. The reticle body 42 includes a pair of opposed si- des 42A and 42B and is positioned or suspended above the base structure 12 such as by air bearings 48. A plurality of interfe--rometer mirrors 50 are urovided on the main body Eor operation wit 42 of the reticle stage 14 L Lh the laser 4interferometer position sensing svste-,n 15 (see Fig. 6) for determining the exact position of the reticle stage which is fed to the position control system,IG in order to direct the appropriate drive signals for moving the reticle stage 14 as desired.

Primary movement. of the reticle stage 14 is accomplished with first electromagnetic drive assembly or means in the form of separate drive assemblies 52A and 523 on each of the opposed sides 42A and 42B, resr)ectively The drive assemblies 52A and 52B include drive coils 54A and "ixedly mounted on the ret 54B L- icle stage 14 at the sides 42A and 421D, respectively, for cooperating with magnet tracks 56A and 562 on the magnet track arms 24 and 26, espectively, of the drive frame 22. While in the prefferred embodiment of the invention the magnet coils are mounted on the reticle stage and the magnets are mounted on the drive frame 22, the positions of these elements of the electromagnetic drive assembly 52 could be reversed.

1 I. --.1.

i 0 Here, the structure of the reticle stace 14 will be explained further in detail. As shown in Fig. 1, the stage body 42 is installed so that it is free to move in the Y direction in the rectangular space inside the driving frame 22. The air bearing 48 fixed under each of the -four corners of the stace bodv 42 makes an ex,--r-emely small air gap between the pad surface and the base surface 12A, and buoys up and supports the entire stage -_-_1 from the surface!2A. These air bearings 48 should preferably be pre-loaded types with a recess for vacuum attraction to the surface 1 As shown in Fig. 2, a rectangle opening 46 in the center of the stage body 42 is provided so that the projected image of the pattern for-med on the reticle 44 can go throu( 1_ - _L 7h. In order 'or the projected mage via the rectangle opening 46 to pass through the project:ion optical system PL (See Fig. 5) which is installed below the rectangle opening, there is another opening 12B provided at he center part of the base structure 1-2. The reticle 44 Js loaded on the top surface of the stage body by clamping members 42C which are protrusively placed at four points around the rectangle opening 46, and cla-,,iDed by the vacuum pressure. is fixed Now, the in erEerometer mirror 50Y, wn- near the side 422 of the stage body 42 near the arm 26, has a vertical elongate ref7lecting surface in the X direction which length is so-,-.iehwa7_ longer than the movable stroke of the stage 14 in the X direction, and the laser IDeam LBY From -I - -, the Y-axJs int:erferometer is incidenz perpendicularly on:he reflecting surface. In Fia. 2, the -'aser beam LEY is bent at a right angle by the mirror 12D which is fixed on the side of the base structure 12.

is Referring now to Fig. 3 as a partial cross-sectional drawing oj_ the 3-3' view in Fig. 2, the laser beam LBY which is incident on the reflecting surface of the interferometer mirror 50Y is placed so as to be on the same L plane as the bottom surface (the surface where the pattern is formed) of the reticle 44 which is mounted on the ciamping member 42C. Furthermore, in Fig. 3, the air bearing 20 on the end side of the support brackets 18 against the guiding surface 17B of the g-uiding member 17 is also shown. " Referring once again to Figs. 1 and 2, the laser beam LBX1 -from the Xi- axis interferometer is incident and reflected on the interferometer mirror 50X1, and the laser beam LEX2 from the X2-axis interferometer is incident and reflected on the -interzferometer mirror 50X2. These two mirrors 5OX1 and 50X2 are structured as corner tube type mirrors, and even when the stage 14 is in yaw rotation, thev always maintain the incident axis and reflecting axis of the laser beams parallel within the XY plane. Further-more, the block!2C in Fig. 2 is an optical block such as a prism to orient the laser beams LEX1 and LEX2 to each of the mirrors SOX1 and 5OX2, and is fixed to a part The corresponding block for - o the base structure 12. the LBy laser beam is not shown.

in Fic. 2, the distance DL in the Y direction between " the two laser beams L3X! and each of the center lines oL LBX2 is the length of the base line used to calculate the amount of yaw rotation. Accordingly, the value of the difference between the measured value AX1 in the X directIon of the XI- axis interferometer and the measured value,-,X2 in the X direction of the X2-axis interferometer divided by the base line length BL is the approximate amount cl:: yaw rotation in an extremely small range. Also, 2 0 " the nXi and LX2 represents the the sum, of the value oL haij X coordinate position of the entire stage 14. These calculations are done on the high speed digital processor in the position control system 16 shown in Fia. 6.

Furthermore, the center lines of each of the laser beams LEXI and LRX2 are set on the same surface where t--!-,e nattern is -formed on ne reticle 44. The extension of the : the line GX, which is show-n in Fig. 2 and divides in hall f laser beams LBX1 space between each o" the center lines ol and LEX2, and the extension of the laser beam LEY intersect within the same surface where the nattern is formed. And furthermore, the ontical axis AX (See Figs. 1 and 5) also crosses at this in--ersection as shown in Fig. 1. In Frig. 1, a slit shape il-lumminazion field!LS which includes the - L - - - optical axis A.X is shown over the reticle 4,C, and the pattern image of zhe reticle 44 is scanned and exposed onto the iDhoto-sensitive substrate via the projection optical system PL.

Furthermore, ihere are two rectangular blocks 90A and 9CS -fixed on the side 42A of the stage body 42 in Figs. 1 and 2. These blocks 90A and 903 are to receive the driving force in the Y direction from the second electro-magnetic actuator 70 which is mounted on the carrier/follower 60. Details will be explained later.

The drivi-g coils 54A and 54B which are fixed on the both sides of the stage body 42 are formed flat parallel to the XY plane, and pass through the magnetic flux space in the slot which extends in the X direction of the magnetic track 56A and 56B wihout: anv contact. 'The assembly of the driving C04LI 54 and the magnetic track 56 used in the present embodiment is a commercially easily accessible linear motor for general purposes, and it could be either with or without a commutator.

is Fere, considering the actual design, the moving stroke of the reticle stage 14 is mostly determined by the -":' the reticle 44 (the amount of movement recruired at size ol the time of scanningfor ex-ocs-ure and the amount of movement needed at the time of removal of the reticle -from the illum4nation ootical svstem 1.o change the reticle). in the case of the =esent embodim=-, when a 6--1nch (15.24 cm) reticle is used, the movirg-strcke is about 30 cm.

As mentioned before, the driving frame 22 and the stage 14 are independently buoyed up and supported on the base-surface 12A, and at the same time, magnetic action and reaction force is applied to one another in the X direction f that, the law o-l' onlv by the linear motor 52.;ecause o : moment ving the conservation of _um is seen between the dri -C frame 22 and the stage 14.

Now, sur)pose the weight of the entire reticle stage f the frame 22 14 is about one fifth of the entire weight o-1 which includes the support brackets 18, then the forward movemen: of 30 cm of the stage!-_! in. the X direction makes the drivina frame 22 move by G cm backwards in the X direction. This means that the location of the center of ' the apparatus on t'he base structure 12 - the gravity o is essentially fixed in the X direction. In the Y direct-cn, there is no movement of any hea%ry object. There"ore, the E the gravt in the change in the location of the cenzer c' t-y - Y direction is also relativeiv -'_ixed.

The stage 14 can be moved in the X direction as described above, but the movinq coils (S4A, 54S) and the Eere stators (56A, SGE) of the linear motors S2 will interf with each other (collide) in the Y direction without an X direction actuator. Therefore, the carrier/follower 60 and the second electromagnetic actuator 70, which are the -is- J on, are characteristic components of the present inventprovided to control the stage 14 in the Y direction.

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

As shown in Fig. 1, the carrier/follower 60 is movably installed in the Y direction via the hook like support bracket 62 which straddles over tne guiding member 17. Furthermore as evident from Fig. 2, the carrier/follower 60 is iDlaced above the arm 24, so as to maintain a certain space between the stage!4 (the body 42) and to the arm 24, respectively. One end 602 of the ca rrier/follower 60, is substantially protruding inward (toward the stage body 42) over the arm, 24. inside this end part 60E is fixed a driving coil 68 (same shape as the coil 54) which enters a slot space of the magnetic track 56A.

Furthermore, the bracket 62 supported air bearing 66A (See Figs. 2, 3, A and 5) acrainst the guiding surface 17A of the guiding mernber 17 is fixed in the space between -the the carrier/follower 60 and the arm guidina meruDer 17 o 2,1- The air bearing 66 to buoy up and support the carrier/ f ol lower 60 on the base surface 12P is also shown in Fig. 3.

The air bearing 66B awainst the guidincr surface 17B of the guiding member 17 is also fixed to the free end o support brack et 62 on the other side cl' the hook from air bearing 66A with guiding member 17 therebeween.

Now, as evident from Fig. 5, the carr ier/f cl lower 60 is arranged so as to keen certain spaces with respect to both the magnetic track 56A and the stacre body 42 in the Y and Z directions, respectively. Shown in Fig. 5 are the 1Drojection ootical the base structure system PL and column rod CE to support !2 above the projection optical system is P--. 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 ' teral shLEt (mechanical distortion) between the column a L. - I- L_ rod C2 and the projection optical system PL, and thus resu r It- in a deflection of the image on the photosensir-ive su!Dsrate at the time of exposure. Hence, the merit of the device as in the oresent embodiment where the Motion oJ the stage 14 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 exDlained. In Fig. 4A, 1)-e carrier/ffollower GO is disassembled into two parts, 60A and 602, for the sake of facilitating one's understanding. As evident -From Fig. 4A, the driving coil 68 to move the carrier/folicwer 60 itself in the X direction is fixed at the lower nart of the end 6CE of the carrier/follower 60. Furthermore, -the air bearng 66C is placed against the base structure 12A on the bottom surface of the end GOE and helps zo buoy up the carrier/follower 60.

L_ Hence the carrier/follower 60 is suoported in the Z directi-on with the following three points, the two a-Lr bearings 66 and one air bearing 66C, and is constrained in the Y direction for movement in the X direction by air bearings 66A and 66B. What is important in this structure s th_at the second electromagnetic actuator 70 is arranged back to back with the support bracket 62 so that when the actuaT--or generates the driving force in the Y direction, reaction forces in the Y direction between the stage!,- and the carrier/follower 70 actively act upon -the air bearings 66A and 662 which are fixed inside the suL)Dort bracket 62. In other words, arranging the actuator 70 and the air bearings 66A, 66B on the line parallel to the y-axis in _ -, 0 is XY plane hel-ps prevent generating unwanted stress, which might deform the carrier/f ol lower 60 mechanically when the actuator 701 is in. operation. Conversely, it means that it s possible to reduce the weight of the carrier/ f ol lower L- 60.

As evident from Figs. 2, 4A and 4C described above, f:- the driving frame -he magnetic track 56-A in the arm 24 o 22 provides magnetic flux for the driving coil 54A on the stage body 42 side, and concurrently provides magnetic flux for the driving coil 68 for the carrier/follower 60. As for the air bearinzs 66A, 66B and 66C, a vacuum pre-loaded type is preferable, since the carrier/f ol lower 60 is light. Desides the vacuum pre-loaded type, a magnetic pre-loaded type is also acceptable.

Next with reference to Figs. 3, 419 and 5, the second actuator mounted on the carrier/follower 60 will be exnlained. A second electromagnetic drive assembly in the.form c' a voice col motor 70 is made,ur) of a voice coil 74 attached to the mair body 42 of the reticle stacre 14 and a... agnet 72 attached to the carrier/follower 60 to move the stage 14 for small displacements in the Y direction in the plane of the travel of the stage 14 orthogonal to the X direction long linear motion produced by the driving assembly 22. The positions of the coil 74 and magnet 72 could be reversed. A schematic structure of L-he voice coil motor (VCM) 70 is as shown in Figs. 3 and 5, and the detailed structure is shown in Fig. 419. Shown in Fig. 45 is a cross-sectional view of the VCM 70 sectioned at the horizontal plane shown with an arrow 4B in Fig. 5. In Fig. the VCM 70 are fixed onto the 3, the magnets 72 o the VCM 70 carr,,er/follower 60 side. And the coil o_ comprises the coil body 74A and its supporting part 74B, and the supporting part 74B is fixed to a connecting plate 92 (a plate vertical to the XY plane) which is rigidly laid across the two rectangular blocks 90A and 903. A center line KX of the VCM 70 shows the direction of the driving force of the coil 74, and when an electric current flows through the coil body 74A, the coil 74 displaces into either positive or negative movement in the Y direction in accordance with the directicn of the current, and generates a force correspondent to the amount of the current. Normally, in a commonly used VCM, a ring-like damper or bellows are provided between the coil and magnet so as to keep the gap between the coil and magnet, but according to th e present embodiment, that: gao is kept by a follow-up motion of the carrier/f ol lower 60, and therefore, such supporting elements as a damper or bellows are not necessary.

In the uresent embodiment, capacitance gan sensors 13A and 133 areprovided as a positioning sensor 13 (see Fig. 6) as shown in Fig. 4B. _Tn Fig. 43, electrodes for capacitance sensors are placed so as to detect the change in the gap in the X drecticn!Detween the side surface of the rectangular blocks 90A and 90B facing with each other in the X direction and the side surface of a case 701 of the VCM 70. Such a oositionina sensor 13 can be ulaced anywhere as far as it can detect the gan change in the Y direction between the carrier/follower 60 and the stacre!4 (or the body 42). Furthermore, the type of the sensor can be any of a non-contact ty-pe such as photoelectric, inductive, ultrasonic, or air-micro system.

The case 701 in F_q. B is form- i with the carrier/f ol lower 60 in one, and r)lacec (spatially) so as not to contact any member on the reticle stage 14 side.7--s -P to-r the gan between the case 701 and the rectangular blocks 90A and 902 in the X direction (scanning direction), when the gan on the sensor 13A side becomes wider, the gar) on,the sensor 13 B side becomes smaller. Therefore, if the difference between the measured gap value by the sensor!3A and the measured cTap value by the sensor 133 is obtained by either digital operation or analog operation, and a direct servo (feedback) control system which controls the driving f= the car-ier/Jollower 60 current of the driving coil 68 f is designed using a servo driving circuit which makes the gap difference zero, then the carrier/ fol lower 60 will automatically perfo= a follow-up movement in the X direct-ion always keeping a certain space to the stage body 42. Or, it is also possible to design an indirect servo control system which controls an electric current- flow to the driving coil 68, with the operation of:Dosition control system 16 in Fig. 6 using the measured gap value obtained only from one of the sensors and the X coordinate position c the stage 14 measured from the X axi ol _s 4-terferometer, withoufusing the two gap sensors 13A and 133 diffferentially.

Tn the VCM 70 as described in Fia. 43, the gap between the coil body 74A and the magnet 72 in the X direction (non-energizincr direction) is in actuality about 2 - 3 mm. Therefore, a fiollcw-un accuracv of the carr i er/ fol lower 60 with resDect to the staae body 42 would be acceptable a't around -. 5 - I mm. This accuracv der)ends on ol on how much of -the yaw rotat' E the stage body is f the line in the allowed, and also depends on the length oj- "directon (energizing direction) of the coil body 74A of the VCM 70. Furthermore, the degree of the accuracy for z:his can be. substantially lower than the precise positioning accuracy for the stage body 42,,_:, s_ing an interferometer (e.g., 0_03 im supposing the -resolution of the interferometer is 0.01 pm.) This means that the servo system for a follower can be designed fairly simply, and the amount of cost to install the follower control system would be small. Furthermore, the line KX in Fig. 4_3 is set so as to go through the center of the grav ity of the entire stage 14 on the XY plane, and each of centers of the pair of the air bearing 66A and 662 provided inside the support brackets 62 shown in Fia. 4 is also positioned on the line KX:Ln the XY clane.

Shown in Fig. 4C is a cross-sectional drawing of the Dart which includes the guiding member 17, the carrier/follower 60, and the magnetic track 56A sectioned from the direction of the arrow 4C in Fig. 2. The arm 21! storing the magnetic track 56A is buoyed up and supported on the base surface!2A by the air bearing 32, and he is carriier/.fol lower 60 is buoved uo and sunnorted on z:he base surface 12A by the air bearing 66. At this time, the height of the air hearing 43 at the bottom surface of the stage body 42 (see Figs. 3.or 5) and the height of the air bearing 32 are determined so as to place the driving coil 541A on the stage body 12 side keeping a 2 - 3 mm gap in Z direction in the slot space of the magnetic track 5GA_.

Each of the spaces between the carrier/follower 60 and the arm 24 in the Z and Y directions hardly changes because they are both guided by the common guiding member 17 and the base surface 12A. Further-more, even if there is a difference in the height in the Z direction between the part on the base surface 12A where the air bearing 32 at the driving frame 22 (arm 24) is %-he bottom surface o_ guided and the part on the base surface 12A where the air :ace o-- hearing 48 at the bottom sur4 F the stage body is guided, as long as the difference is precisely constant within the moving stroke, the gar) in the Z direction T r_ is between the magnetic track 56A and the driving co-41 S4A is also preserved consta.-it.

Furthermore, since the driving coil 68 for the carrier/follower 60 is originally fixed to the carrier/follower 60, it is arranged, maintaining a certain f the f 2 - 3 mm above and below in the slot space o gan o magnetic track 56.7. And the driving co-il 68 hardly shifts in the Y direction with respect to the magnetic track 56A.

Cables 82 (see Fig. 2) are provided for directing the signals to the drive coils 54A and 5413 on stacre 14, the voice coil motor coil 74 and the carrier/follower drive coil 68, and these cables 82 are mounted on the carrier/follower 60 and guide 17 thereby eliminating drag on the reticle stage 14. The voice coil motor 70 acts as a buffer by denving transmission of external mechanical disturbances to the stacre 14.

Therefore, referring now to Figs. 2 and 4A, the cable issues will be described further in detail. As shown in Fig. 2, a connector 80 which connects wires of the electric system and tubes of the air pressure and the vacuum system (hereinafter called "cables") is mounted on the base structure 12 on one end of the guiding member!7. The connector 80 connects a cable 81 from the external control system (including the control system of air pressure and vacuum system besides the electric system control system shown in Fia. 6) to a f lexible cable 82. The cable 82 is Further connected to the end part 60E of the carrier/ f ol 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 ar)tears as moment in unexpected direction between the carrier/follower 60 and the stage body 42. In other ' the cable 82 gives the words, the tension o. carrier/ fol lower 60 a force to rotate the guiding surface of the guiding member 17 or the base surface 12A, and the tension of the cable 83 gives a force to the carrier/follower 60 and the stage body to rotate relatively.

One of these moments, the constituent which shifts the carrier/ f ol lower 60, is not problematic, but the one which shifts the stage body in X, Y, or e direction (yaw rotation dir ection) could affect the alignment or overlay accuracy. As for in X and e directions, shifts can he corrected by a consecutive drive by the two linear motors (54A,56A,S42,56,B), and as for in the Y direction, the shift can be corrected by the VCM 70. In the present embodiment, since the weight of the entire stage 14 can be reduced substantially, the resoonse o" the motion of the stage 14 by VCM 70 in the Y direction and the response by the linear motor in X and 0 directions will be extremely high in cooneration with the completely non-contact a-uidless structure. Furthermore, even when a micro vibration (micron order) is generated in the carrier/follower 60 and it is transferred to the stage 14 via the cable 83, the vibration (from several Hz to tens of Hz) can be sufficiently canceled by the above mentioned high response.

Now, Fig. 4A shows how each of the cables is distributed at the carrier/follower 60. Each of the driving signals to the driving coil 54A, 54B for the stage body 42 and the driving coil 74 of the VCM 70 and the from the posit detection signal --ion sensor 13 (the gap sensors 13A, 13S) go through the electric I system wire 82-k from the connector 80. The pressure gas and the vacuum to each of the air hearings 48 and 66 go through the pneumatic system tube 82B from the connector 80. On the other hand, -he driving signal to the driving coil 54A and 54B goes L through the electric system wire 83A which is connected to f the stage body 42, and the pressurized gas.or the air bearing 48 and the vacuum for the clamping member 42C go through the pneumatic system hoses 831;.

Furthermore, it is preferable to have a separate line for the pneumatic system for the air bearings 20, 20' and J" the one shown in 32 of the driving frame 22, independent ol Fig. 2. Also, as shown in Fig. 4A, in case the tension or vibration of the cable 83 cannot be prevented, iL -JS advisable to arrange the cable 83 so as to limit the moment by the tension or -vibration the stage body 42 receives only case, the o Y direction as much as Possible. 7n -_)nat moment can be canceled only by the VCM 70 with the highest response.

Referring now to Figs. 1, 2 and 6, the nositioning of the reticle stace!4 is accomplished firsz knowing its existing position utilizing the liaser irterferometer system 15. Drive signals are sent to the re!-c - le stage drive coils 54A and 54-B for driving the stage in the X direction. A difference in the resulting drive to the opposite sides 42A and 42B of the reticle stage 14 will produce small yaw rotation of the reticle stage 14. An az)Drooriate drive signal to the voice coil 72 oF voice coil motor 70 -oroduces small displacements of the reticle stage " the reticle 14 in the Y direction. As the position o.

Stage 14 changes, a drive signal is sent to the follower 60 to carrier/fLollower coil 68 causing the carrier/i Z - on forces to tollow the reticle stage 14. Resulting reaci the applied drive fo-rces will move the magnetic track assembly or drive frame 22 in a direction opposite to the movement of the reticle stage 14 to substantially maintain is the center o.L gravity of the apparatus. It will be appreciated that the counter-weight or reaction movement of the magnetic track assembly 22 need not be included in the apparatus in which case the magnetic track assembly 22 could be fixedly mounted on the base 12.

As described above, in order to control the stage system according to the present embodiment, a control system as shown in Fig. 6 is installed. This contro system in Fig. 6 will be further explained in detail here. X1 driving coil and X2 driving coil composed as the driving coils 54A and 54B of two linear motors respectively, and Y driving coil composed as the driving coil 72 of the VCM 70 are nlacedin the reticle stage 14, and the drivinq coil 68 is iDlaced in the carrier/follower 60. Each of these driving coils is driven in response to the driving signals SX1, SX2, SY1, and SLX, respectively, from the positlon control system 16. The laser interferometer system which measures the coordinates position of the stage 14 comprises the Y axis interferometer which sends/recei4ves the beam '-BY, the X1 axis in- _erferometer which sends/receives the beam LBX1, and the X2 axis interL'- erometer which sends/receives the beam LEX2, and they send position information for each of the directions of the axes,!FY, IFX1, IFX2 to the Dosition control system 16. The postion control system 16 sends two driving signals SXI and SX2 to the driving coils 54A and 54B so that the difference between the position information IFX1 and IFX2 in the X direction will become a preset value, or in other words, the yaw rotation of the reticle stage 14 is maintained at the sr)ecified amount. Thus, the yaw rotation (in 6 direction) positioning by the beams LBX1 and LEX2, X! axis and X2 axis interferometers, the position control system 16, and the driving signals SX1 and SX2 is constantly being conducted, once the reticle 44 is aligned on the stage body 42, needless to mention the time of, the exposure.

Furthermore, the control system 16, which obtained the current coordinates position of the stage 14 in the X direction from the average of the sum of position information IFXI and IFX2 in the X direction, sends the driving sJcnals SX1, SX2 to the driving coils 54A and 543, res- oectively, based on the various commands from the Host CPU!61 and the infor-mation CD for the parameters. 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 diff-erent forces as needed.

i 5 Furthermore, the position infor-mation IFY from the Y axis interferometer is also sent to the control system 16, and the control system 16 sends an optimum driving signal the carrier/flollower 60. At S,,-,X to the driving coil 68 o tha'. time, -the control system 16 receives the detection s-,-gnal 5,,,from the nosition sensor 13 which measures the space between the reticle stage 1,- and the carrier/follower 60 in the X direction, and sends a necessary signal SAX to make the signal 5,, into the preset value As mentioned before, the follow-up accuracy for the carri er/ Ifol lower 60 s not so strict that the detection signal S P. of the control system 16 does not- have to be evaluated strictly either. For example, when controlling the motion by reading the position information IFY, IFXl, IFX2 ever-y imsecond from, each of the interferometers, the high speed processor in the control system 16 samples the current of the detection signal 5 P, each time, determines whether the value is large or small com; Dared to the reference value (acknowledge the direction), and if the deviation surpasses is a certain point, the signal SAX in proportion to the deviation can be sent to the driving coil 68. Further-more as mentioned before, it is also acceptable to install a control system 95 which directly servo controls the driving coil 68, and directly controls the follow-up motion of the carrier/f ol lower 60 without going through the position control system 16.

Since the moving stage system as shown has no attachment to constrain it in the X direction, small influences may cause the system to drift toward the positive or negative X direction. This would cause certain parts to collide after this imbalance became excessive. The influences include cable forces, imprecise leveling of :erence surface 12A or friction between the base ref com-Donents. one simple method is to use weak bumpers (not the drive assembly shown) to prevent excessi-ve travel of 22. Another simple method is to turn off the air to one or more of: the air bearings (32,20) used.to (guide the drive assembly 22 when the drive assembly reaches close to the the stroke. The ai-- bearing(s) can be turned on end ol when the drive begins to move back in the o-pposite direction.

More precise methods require monitoring the position of the drive assembly by a measuring means (not shown) and force to restore and maintain the applying a driving j correct position. The accuracy of the measuring means need not be precise, but on the order of 0.1 to 1.0 mm. The driving force can be obtained by using another linear motor (not shown) attached to the drive assembly 22, or another motor that is coupled to the drive asse-ably.

Finally, the one or more air bearings (66,66A,66B) of 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 carrier/ f ol lower Go is energized with the carrier/ f ol lower 60 in the braked condition the drive assembly will be driven and accelerated. Thus, the position control system 16 monitors the location of the drive assembly 22. When the drive assembly drifts out of position, the drive :Jcient accuracy b- assembly is repositioned with suff y intermittently using the coil 68 of the carr-Jer/f ol lower 22.

In the first embodiment of the present invention, the driving frame 22 which functions as a counter weight is installed in order to prevent the center of the gravity of the entire system from shiftin< L_ g, and was made to move in the opposite direction from the stage body 42. However, when the structures in Figs. 1 - 5 are applied to a system where the shift of the center ot" the gravity is not a major problem, it is also acceDtable to fix the driving frame 22 on the base structure 12 together. In that case, except for the problem regarding the center of the gravity, some oj'-' the effects and function can he applied without making any chai.ges.

This invention provides a stage which can be used for high accuracy position and motion control in three degrees o':-' freedom in one plane: (1) long linear motion; (2) short linear motion perpendicular to the long linear motion; and (3) small yaw rotation. The stage is isolated from mechanical disturbances of surrounding structures by utilizing electromagnetic forces as the stage driver. By further using a structure for this guideless stage, a high control bandwidth is attained. These two factors contribute to achieve the smooth and accurate operation of the stage.

Description of the Preferred Ernbodiment

28- Bearing in mind the description of the embodiment illustrated in Figs. 1- 6, the preferred embodiment of the present invention is illustrated in Figs. 7 and 8 wherein the last two digits of the numbered elements are similar to the corresponding two digit numbered elements in Figs. 1-5.

in Figs. 7 and 8, differing from the urevious first n frame which functions as a counter er-,Lbodiment, the drLvweight is removed, and each of the magnet tracks 156A and 156B of the two linear motors is rigidly mounted onto the base structure 112. The stage body 143 which moves straight in the X direction is placed between the two magnetic tracks 156A and 156B. As shown in Fig. 8, an opening 112B is formed in the base structure 112, and the stage body 142 is arranged so as to straddle the opening part 112B in the Y direction. There are four 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 support the stage body 1,2 against the base surface -112A.

Furthermore, according to the present embodiment, the reticle 144 is clamped and supported on the reticle chuck plate 143 which is separately placed on the stage body 142. The straight mirror 150Y for the Y axis laser interferometer and two corner mirrors 150Xl, 15OX2 for the X axis laser interferometer are mounted on the reticle chuck plate 1,3. The driving coils 154A and 154B are horizontally fixed at the both ends of the stage body 142 Jn the Y direction with respect to the magnetic tracks 156A and 1569, and due to the control subsystem previously described, make the stage body 142 run straight in the X direction and yaw only to an extremely small amount.

As evident from Fig. 8, the magnetic track 1569 of the right side of the linear motor and the magnetic track is 156A of the left side of the linear motor are arranged so as to have a difference in level in z direction between them. In other words, the bottom surface of the both ends f the magnetic track 156 in the direction of the long axis of on the left: side is, as shown in Fig. 7, elevated by a certain amount with a block member 155 against the base surface 112A. And the carrier/ follower 160 where the VCM is fixed is arranged in the space below the elevated magnetic track 156A.

The carrier/ follower 160 is buoyed up and supported by the pre-loaded air bearings 16G (at 2 points) on the base surface 112A' of the base structure 112 which is one level lower. Furthermore, two pre-loaded air bearings 1-64 against the vertical guiding surface 117A of -the straight guiding member 117, which is mounted onto the base ace of the structure 112, are fixed on the side surf carrier/follower 160. This carrier/follower 160 is different from the one in Fig. 4A according to the previous emL-cdiment, and the driving coil 168 (Fig. 7) for the carr- Jer/follower 160 is fixed horizontally to the part which extends vertically from the bottom of the carrier/ fol lower 160, and positioned in the magnetic flux slot of the magnetic track 1 56A without any contact. The carrier/follower 160 is arranged so as not to contact any part of the magnetic track i5GA within the range of the moving stroke, and has the VCM 170 which positions the stage body 142 precisely in the Y direction.

Furthermore, in Fig. 7, the air bearing 166 which buoys up and supports the carrier/ fol lower 160 is provided under the VCM 170. The follow-up motion to the stage body 142 of the carrier/fol lower 160 is also done based on the detection signal from the position sensor 13 as in the previous embodiment.

In the second embodiment structured as above, there is an inconvenience where the center of the gravity oil 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 weight. It is, however, nossible to position the stage body 142 precisely 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/follower 160. 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 of 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 stage because the force moment of each of the linear motors substantially cancels with the other- Furthermore, since an elongated.ax-is of action (the line KX in Ficy. 4B) of the VCM-170 is arranged so as to pass through the center of the gravity of the entire structure of the stage not only on the XY plane but also in the Z direction, it is more difficult for the driving force oE the VCM 170 to give unnecessary moment to the stage body f 14-2. Furthermore, since the method of connecting the cables 82, 83 via the carrier/follower!60 can be applied in the same manner as in the first embodiment, the problem regarding the cables in the completely non- contact guideless stage is also improved.

The same guideless principle can be employed in another embodiment. For example, in schematic Figs. 9 and 10, the stage 242, supported 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 magnetic track is is -. 0 rigidly attached to the base 212. The center of the coil is located close to the center of gravity of the stage 242. To move the stage in the Y direction, a pair of VCM's (274A,274B,272A,272B) 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 carrier/ follower stage 260. The carrier/f ol lower stage is guided and driven like the first embodiment previously described.

This alternative embodiment can be utilized for a wafer stage. Where it is utilized for a reticle stage the reticle can be positioned to one side of the co-41 254 and L-rack 256, and if desired to maintain the center of gravity "the stage 242 passing through the coil 254 and track 256, a compensating opening in the stage 242 can be ' the ccJl 254 and track 256 provided on the opposite side oj from the reticle.

Merits gained from each of the emLbodiments can be roughly listed as follows. To preserve accuracy, the carrier/follower design eliminates the problem of cable drag for the stage since the cables connected to the stage follow the stage via the carrier/follower. Cables connecting the carrier/follower to external devices will have a certain amount of drag, but the stage is free from such disturbances since there is no direct connection to the carrier/follower which acts as a buffer by denying the transmission of mechanical disturbances to the stage.

Furthermore, the counter-weight design preserves the location of the center of gravity of the stage system during any stage motion in the long stroke direction by using the conservation of momentum principle. This apparatus essentially eliminates any reaction forces is between the stage system and the base structure on which the stage system is mounted, thereby facilitating high acceleration while minimizing vibrational effects on the system.

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

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

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

--- z, -,, 1 '-'- --- 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; 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 second portion comprises a magnet member.

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

34

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 exposure apparatus according to Claim 7, wherein said bearing is a non-contact bearing which opposes said stage to therebetween.

said base structure without any contact

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

10. An exposure apparatus according to Claim 9, wherein said position detection device comprises a reflective 20 surface located on said stage.

11. An exposure apparatus according 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 stage with regard to said scanning direction during the movement of said stage.

13. An exposure apparatus according to Claim 9, 10 or 11, 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.

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

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

16. An exposure 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.

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 object.

18. An exposure apparatus according to Claim 17, wherein said 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.

20. An exposure apparatus according to any one of the preceding claims, wherein said exposure device includes a 36 mask which defines said pattern.

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

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

23. A scanning exposure method to transfer a pattern onto an object, comprising: moving a stage in a scanning direction, the stage being movably supported by a base; moving a balancing portion in the scanning direction responsive to the movement of said stage, said balancing porting being movably supported by the base; and exposing said pattern onto the object while said stage is moved in the scanning direction.

24. A method according to Claim 23, 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.

25. A method according to Claim 24, wherein said first portion and said second portion are controlled to remain out of contact with each other.

26. A method according to Claim 24 or 25, wherein said first portion comprises a coil member and said second portion comprises a magnet member.

37

27. A method according to Claim 24, 25 or 26, wherein the stage and the balancing portion are arranged to move in a manner in accordance with the law of conservation of 5 momentum.

28. A method according to Claim 23, 24, 25, 26 or 27, wherein said first drive device comprises a linear motor.

29. A method according to any one of Claims 23 to 28, including moving the stage over a surface of said base structure via a bearing.

30. A method according to Claim 29, wherein said bearing is a non-contact bearing which opposes said stage to said base structure without any contact therebetween.

31. A method according to any one of Claims 23-30, further including detecting a position of said stage by means of a position detection device.

32. A method according to Claim 31, wherein said position detection device comprises a reflective surface located on said stage.

33. A method according to Claim 32, wherein said reflective surface is a corner-cube type mirror.

34. A method according to Claim 31, 32 or 33, wherein said position detection device detects a position of said stage with regard to said scanning direction during the movement 38 of said stage.

35. A method according to Claim 31, 32 or 33, 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.

36. A method according to Claim 31, 32, 33, 34 or 35, including correcting yaw rotation of said stage by means of a control system and based on a detection result by said position detection device.

37. A method according to Claim 36, wherein said control system is connected to said first drive device.

38. A method according to any one of Claims 23 to 37, and including moving said stage in a direction which is different from said scanning direction by means of a second drive device.

39. A method according to any one of Claim 23 to 38, wherein said exposure device includes a projection system which projects said pattern onto said object.

40. A method according to Claim 39, wherein said stage is located above said projection system.

41. A method according to Claim 39 or 40, wherein said projection system projects the pattern optically.

)o

42. A method according to any one of Claims 23 to 41, 39 wherein said exposure device includes a mask which defines said pattern.

43. A method according to Claim 42, wherein said stage 5 holds said mask.

44. A method according to any one of Claims 23-43, wherein said balancing portion operates without a drive source.

45. A scanning type exposure apparatus substantially as hereinbefore described with reference to, and as illustrated in, Figs. 1-6, 7 and 8, or 9 and 10 of the accompanying drawings.

46. A scanning exposure method apparatus to transfer a pattern onto a object substantially as hereinbefore described with reference to, and as illustrated in, Figs. 16, 7 and 8, or 9 and 10 of the accompanying drawings.

47. An object moving apparatus which includes a first movable member for moving linearly at least in a first direction on a reference surface of a base structure, said apparatus comprising:

(a) a first fluid bearing system for suspending said first movable member from said reference surface; (b) a guide member mounted on said base structure, which includes a guiding surface elongated in the first direction for constraining a direction intersecting the first direction; (c) a second movable member located adjacent the side of the first movable member, which is capable of moving in the first direction by conforming with said reference surface and said guiding surface; (d) an electromagnetic linear driving system disposed between said first and second movable members, said system including a first magnetizing member mounted on said first movable member and a second magnetizing member mounted on said second movable member in order to generate a driving force toward the first direction; and (e) a second fluid bearing system for suspending said second movable member from said reference surface independently from said first movable member and for engaging said guiding surface keeping a space between said first and second magnetizing members; wherein said first and second movable members are reversely moved in the first direction by energizing said electromagnetic linear driving system.

48. Positioning apparatus comprising:

stage; base structure; carrier/follower; first electromagnetic means of a commutated nature supported on said base structure for magnetically positioning said stage, said first means being capable of moving said stage in a first linear direction; second electromagnetic means supported on said carrier/follower for magnetically positioning said stage, said second means being capable of moving said stage in a second linear direction substantially orthogonal to said 3 )0 first linear direction for small displacements in said plane; 41 yaw correcting means for correcting small rotation in a plane using the said first or second electromagnetic means; positioning means for positioning said carrier/follower in said first linear direction; means for sensing the position of said stage in said first linear direction and outputting a corresponding signal to said positioning means; and means for controlling the position of said carrier/follower to follow the approximate position of said stage in said first linear direction.

49. The positioning apparatus of Claim 48, wherein said stage includes a pair of opposed sides and said first electromagnetic means includes a pair of drive assemblies, said drive assemblies positioned respectively at said opposed sides of said stage, each of said drive assemblies including a coil member and a magnet member with one of said members fixedly mounted on said stage and the other of said members movably mounted on said base structure whereby said drive assemblies can apply an action force to said stage to move said stage.

so. The positioning apparatus of Claim 49, wherein said movable member can move in response to a reaction force to substantially maintain the centre of gravity of the apparatus.

51. The positioning apparatus of Claim 49 or SO, in which 3 said yaw correcting means includes control means for driving each of said pair of drive assemblies by a different amount.

42

52. A positioning apparatus comprising, in combination: a stage having a pair of opposed sides; a carrier/follower; 5 first electromagnetic commutated means for magnetically positioning said stage and including at least one linear drive means for driving said stage in one linear direction; second electromagnetic means mounted on said carrier/ f ol lower for moving said stage small distances in said plane substantially orthogonal to said one linear direction; and means for controlling the position of said carrier/follower to follow the approximate position of said stage in said one linear direction.

53. The position apparatus of Claim 52, including a base structure and wherein each of said linear drive means includes a coil member and a magnet with one of said members fixedly mounted on said stage and the other of said member movably mounted on said base structure whereby said drive assemblies can apply an action force to said stage to move said stage.

54. The position apparatus of Claim 53, wherein said movable member can move in response to a reaction force to substantially maintain the centre of gravity of the apparatus.

55. The positioning apparatus of Claims 52, 53 or 54, including a base structure and means for suspending said stage above said base structure.

56. The positioning system positioning means mounted positioning said 5 direction.

of Claim on said base carrier/follower in said one linear 55, including structure for

57. The positioning apparatus of any of Claims 48 to 56, wherein second electromagnetic means includes at least one voice coil motor.

58. The positioning apparatus of any of Claims 48 to 56, wherein said second electromagnetic means includes at least a pair of voice coil motors and said yaw correcting means includes control means for driving each of said pair of voice coil motors by a different amount.

59. The positioning apparatus of any of Claims 48 to 58, wherein said first electromagnetic means includes one drive assembly including a coil member and a magnet member with at least one of said members fixedly mounted on said stage and said second electromagnetic means includes a plurality of voice coil motors.

60. Positioning apparatus comprising:

stage having a pair of opposed sides; base structure; means for suspending structure; said stage a driving frame; a carrier/follower; first electromagnetic means of a above said base commutated nature 1 -- - ', Zj ', y; 44 mounted on said base structure for magnetically positioning said stage, said first means being capable of moving said stage in a first linear direction and in a small yaw rotation in a plane; 5 said first electromagnetic means including a pair of drive assemblies, said drive assemblies positioned respectively at said opposed sides of said stage, each of said drive assemblies including a coil member and a magnet member with one of said members fixedly mounted on said stage and the other of said members mounted on driving frame; second electromagnetic means mounted on said carrier/follower for magnetically positioning said stage, said second means being capable of moving said stage in a second linear direction perpendicular to said first linear direction for small displacements in said plane; positioning means mounted on said base structure for positioning said carrier/follower in said first linear direction; 20 means mounted on said base structure for sensing the position of said stage in said first linear direction and outputting a corresponding signal to said positioning means; and means for controlling the position of said carrier/follower to follow the approximate position of said stage in said first linear direction.

61. -- 1 ne positioning apparatus of Claim 60, including means for driving said carrier/follower from one of said members of one of said drive assemblies.

62. The positioning apparatus of Claim 60 or 61, including means for suspending said driving frame above said base structure whereby said drive assemblies can apply an action force to said stage to move said stage and said movable driving frame can move in response to a reaction force to substantially maintain the centre of gravity of the apparatus.

63. A stage apparatus which includes a base structure having a reference surface and a main stage body supported on the reference surface through a gas bearing to move linearly at least in a first direction, said apparatus comprising: (a) a frame assembly including two main arm members elongated in the first direction and parallel with each other, (b) means for supporting said frame assembly on the reference surface of said base structure through a gas bearing independently from said main stage body; 20 (c) a guide member formed on a portion of said base structure, for guiding the movement of said frame assembly in the first direction; (d) two linear motors which respectively include a magneto track mounted linearly in each of said main arm members and a coil member mounted at each of opposite sides of said main stage body to be located respectively in the magnetic flux of said magneto track; (e) a drive control system for energizing each of said coil members simultaneously to move said main stage body and DO said frame assembly reversely in the first direction on the reference surface; - A" 46 (f) a movable follower member for following said main stage body in the first direction by conforming with said guide member to cause it to maintain a predetermined spatial distance from said main stage body; and (9) an electromagnetic actuator for positioning said main stage body in a second direction perpendicular to the first direction inside of said frame assembly while keeping a space between said magneto track and said coil member, respectively, and thereby producing a magnetic force between said main stage body and said movable follower member in the second direction.

64. The stage apparatus of Claim 63, wherein said frame assembly is rectangular and includes two connecting arms connecting end portions of said two main arm members and with said main stage body located between said two main arm members.

65. A stage apparatus providing a first movable member which is supported on a reference surface of a base structure through a fluid bearing and capable of linearly moving at least in a first direction, said apparatus comprising:

(a) two electromagnetic linear driving sources elongated in a first direction parallel each other such that said first movable member is located therebetween, each of said two driving sources including a first magnetizing member mounted on said first movable member and a second magnetizing member elongated in the first direction for interacting magnetically with said first magnetizing member; 47 (b) an installing member for locating said two second magnetizing members with a predetermined space in a second direction perpendicular to the first direction; (c) a linear guide portion formed on said base structure elongated in the first direction; (d) a movable follower member for following said first movable member in the first direction by conforming with said linear guide portion to cause it to maintain a predetermined spatial distance from said first movable member; (e) a non-contact type actuator for generating attraction and repulsion between said first movable member and said movable follower member to move said first movable member in the second direction; and (f) a control system for energizing said two linear driving sources and said non-contact type actuator to position said first movable member in the second direction while moving said first movable member toward the first direction.

66. A stage apparatus according to Claim 65, wherein said installing member is connecting parts for fixing each of said two second magnetizing members on said base structure.

67. A stage apparatus according to Claim 65 or 66, wherein said installing member is a rectangular frame assembly movable in the first direction.

68. A movable stage apparatus which includes a movable member suspended on a referenced surface of a base structure through a fluid bearing system and moving linearly at least 48 in a first direction on the reference surface, said apparatus comprising:

(a) at least one electromagnetic linear driving source elongating in the first direction, said driving source including a first magnetizing member mounted on said movable member and a second magnetizing member mounted on said base structure along the first direction to interact magnetically with said first magnetizing member; (b) a linear guide portion formed on said base structure along the first direction; (c) a follower member for following said movable member in the first direction by conforming with said linear guide portion to maintain a predetermined spatial distance from said movable member; and (d) at least one non-contact type actuator for generating attraction and repulsion between said movable member and said follower member to move said movable member in a second direction perpendicular to the first direction keeping a space between said first and second magnetizing members.

69. A movable stage apparatus as claimed in Claim 68, comprising:

two electromagnetic linear driving sources elongating in the first direction parallel to each other such that said movable member is located therebetween.

70. A movable stage apparatus as claimed in Claim 68 or 69, comprising at least two non-contact type actuators.

71. An object moving apparatus, positioning apparatus or 49 stage apparatus substantially as described herein with reference to Figures 1 to 6, Figures 7 and 8, or Figures 9 and 10 of the accompanying drawings.

J - 7, ',. -,