KR100281856B1 - A scanning type exposure apparatus and a scanning exposure method - Google Patents

Abstract

Disclosed is a device capable of controlling positioning and movement with high accuracy. The device utilizes a rectified linear motor to move the guideless stage in one long straight direction in the plane as well as in small yaw rotations. The carrier / follower receiving a single voice coil motor is controlled to follow the stage in the long straight moving direction. The VCM provides an electromagnetic force to move the stage at microdisplacements in a straight line direction perpendicular to the long straight direction of movement in the plane and ensure proper alignment. One of the rectified linear motors is mounted in a freely driven drive assembly, which is driven by a reaction force to maintain the center of gravity of the device used for yaw correction, using two VCMs. Is achievable.

Description

A scanning type exposure apparatus and a scanning exposure method

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a movable stage capable of precise movement, and more particularly to a stage apparatus capable of high-precision positioning and high-speed movement and capable of moving in one linear direction, which apparatus can be well used in microlithographic systems. will be.

In a wafer stepper, the alignment of the exposure field with respect to the reticle to be imaged affects the success or failure of the circuit in this field. In a scanning exposure system, the reticle and the wafer are moved simultaneously at the time of exposure and scanned across each other. The present invention discloses an apparatus for performing a precise scan movement in connection with such a system.

To achieve high accuracy, the stage must be isolated from mechanical disturbances. This is obtained by positioning and moving the stage using an electromagnetic force. In addition, it must have a high control bandwidth, which requires that the stage be a light and moveable structure. Moreover, the stage should not cause overheating, because interferometer interference or mechanical change may be caused to degrade alignment accuracy.

The rectified electromagnetic alignment devices disclosed in U.S. Patent Nos. 4,506,204, 4,506,205, and 4,507,597 are not feasible in that they require large magnets and coil assemblies that are uneconomical. Also, because of the weight of the stage and the heat generated, these designs are not suitable for high precision applications.

An improvement on such a rectifying device is disclosed in US Pat. No. 4,952,858, which uses a conventional sub-stage mechanically guided in the XY direction to provide large displacement movement in the plane. This eliminates the need for a large magnet and coil assembly. Electromagnetic means installed on this sub-stage allows the stage to be isolated from mechanical disturbances. Nevertheless, the combined weight of the sub-stage and stage still results in low control bandwidth, and there is still heat generated by the electromagnetic elements supporting the stage.

Although the conventional device using rectified electromagnetic means is a significant improvement over conventional non-rectified devices, low control bandwidth and interference problems of interferometers still remain. In such an apparatus, the sub-stage is moved by magnetic force in one straight direction, while the rectified electromagnetic means installed in the sub-stage moves the stage in its orthogonal direction. The sub-stage is heavy because it supports the magnet orbit that moves the stage. Moreover, heat radiation at the stage degrades the interferometer accuracy.

It is also well known to move (e.g., 10 cm or more) the movable member (stage) in one long linear direction by using two parallel linear motors in which a coil and a magnet are coupled. In this case, the stage is guided by a kind of straight guide member and driven in one straight direction by a linear motor provided parallel to the guide member. When driving the stage only to a very small stroke range, a guideless structure constructed by combining some electromagnetic actuators can be adopted, as disclosed in the prior art. However, in order to move the guideless stage a long distance in one linear direction, since a specially structured electromagnetic actuator is required as in the prior art, the apparatus is enlarged, thus causing a problem that power consumption is further increased.

It is an object of the present invention to provide a light weight device in which a guideless stage can be moved in a long linear moving direction by using an electromagnetic force, and low inertia and high response are achieved.

Another object of the present invention is to provide a guideless stage device using a commercially available linear motor as an electromagnetic actuator for linear movement.

Still another object of the present invention is to provide a guideless stage device capable of active and precise position control with respect to the small displacement amount without any contact in a direction orthogonal to the long linear moving direction.

Still another object of the present invention is to provide a movable member (stage main body) moving in one linear direction and a second movable member sequentially moving in the same direction while maintaining a constant space with the movable member. By providing the electromagnetic force (action force and reaction force) in a direction orthogonal to the linear direction between the member and the stage main body, it is to provide a completely non-contact stage device.

A further object of the present invention is to provide a non-contact stage apparatus capable of preventing the positioning and running accuracy from deteriorating by changing the tension of various cables and tubes connected to the non-contact stage main body moving while supporting an object. To provide.

Still another object of the present invention is to provide a non-contact device having a low height by arranging the first and second movable members moving in parallel in opposite straight directions in parallel.

It is still another object of the present invention to provide an apparatus configured not to change the position of the center of gravity of the entire apparatus, even when the non-contact stage body moves in one linear direction.

In order to achieve the main object, the present invention is characterized by the following contents.

Disclosed is a device capable of position and movement control with high accuracy. The device uses a rectified linear motor to not only move the guideless stage in one long straight direction in the plane but also in a small yaw rotation. Carriers / followers that receive a single voice coil motor (VCM) are controlled to approximately follow the stage in the long straight direction of travel. The VCM provides an electromagnetic force to move the stage in a small displacement in a straight line perpendicular to the long straight direction of movement in the plane to ensure proper alignment. This follower design eliminates the problem of cable drag to the stage because the cable connected to the stage follows the stage via the carrier / follower. The cable that connects the carrier / follower with an external device has a certain amount of drag, but because the VCM on the carrier / follower acts as a buffer by preventing mechanical disturbance from propagating to the stage, the stage can eliminate this disturbance. Do not receive.

As a feature of the invention, a rectified linear motor is installed on both sides of the stage and mounted on a drive frame. Each rectified linear motor comprises a coil member and a magnet member, one of which is mounted on either side of the stage and the other on the drive frame. Both motors are driven in the same direction. Driving these motors at slightly different distances will result in less yaw rotation in the stage.

In another aspect of the present invention, using the principle of momentum conservation, a movable counter-weight is provided so that the position of the center of gravity of the stage system is preserved even at any stage movement. In an embodiment of the present invention, the drive frame supporting one member of each linear motor is lifted on the base structure, and when the drive assembly exerts an acting force on the stage to move the stage in one direction on the base structure, the drive frame is By moving in the opposite direction in response to the reaction force, the device's center of gravity is preserved substantially. The apparatus substantially eliminates any reaction forces between the stage system and the base structure on which the stage system is mounted, thereby facilitating high acceleration while minimizing the effects of vibration on the system.

By limiting the movement of the stage to three specific degrees of freedom, the apparatus is simplified. Because of the use of commercially available electromagnetic components, the device design can be easily adapted to changing the dimensions of the stage.

This high-precision positioning device provides a smooth and precise scanning movement in one linear direction and controls precise displacement movements in the direction perpendicular to the scanning direction and less unstable rotation in the plane to ensure precise alignment, thereby providing a scanning exposure. Ideal for use as a reticle scanner for your device.

Other aspects, features and advantages of the present invention will become more apparent from the following detailed description set forth with reference to the accompanying drawings. In each figure, like reference numerals refer to like elements.

1 is a schematic perspective view of a device according to the invention.

2 is a plan view of the apparatus shown in FIG.

FIG. 3 is an elevation view of the structure shown in FIG. 2 taken along the line 3-3 'in the direction of the arrow; FIG.

4A is a partially exploded perspective view of the carrier / follower of FIG. 1, deployed from a positioning guide;

4B is an enlarged horizontal cross-sectional view of a portion of the structure shown in FIG. 5 taken along the line 4B-4B 'in the direction of the arrow;

4C is an enlarged vertical cross-sectional view of a portion of the structure shown in FIG. 2 with the voice coil motor removed, taken along the line 4C-4C 'in the direction of the arrow;

FIG. 5 is an enlarged vertical sectional view of a portion of the structure shown in FIG. 2, taken along the line 5-5 'in the direction of the arrow; FIG.

6 is a block diagram schematically illustrating a sensing and control system for position control of a stage.

7 is a plan view similar to FIG. 2 showing a preferred embodiment of the present invention;

FIG. 8 is a vertical sectional view of the structure shown in FIG. 7 taken along the line 8-8 ′ in the direction of the arrow; FIG.

9 and 10 show another embodiment of the present invention, a schematic view similar to FIGS. 7 and 8;

※ Explanation of codes for main parts of drawing

12: base structure

14: stage

15: laser interferometer system

16: position control system

17: guide member

18, 62: support bracket

22, 52A, 52B: Drive Assembly

24: arm

32, 66A, 66B, 66C: Air Bearing

42: reticle body

44: reticle

54A, 54B, 68, 74: drive coil

56A, 56B: Magnetic Orbits

60 carrier / follower

72: magnet

80: connector

Description of the first embodiment

Although the present invention is generally applicable to electromagnetic alignment devices, preferred embodiments include injection devices for reticle stages as shown in FIGS.

Referring to the drawings, the positioning device 10 according to the present invention includes a base structure 12 in which the reticle stage 14 is supported and moved as necessary, a laser interferometer system 15 for tracking the position of the reticle stage, and a position sensor. 13, and a position control system 16 operated by the CPU 16 '(see FIG. 6).

The elongated guide member 17 for positioning is mounted on the base 12, and the support bracket 18 (two brackets of the illustrated embodiment) is for example guided by the air bearing 20. It is supported to be movable on the plane. The support bracket 18 is connected to the drive assembly 22 or the drive frame in the form of a magnet track assembly in order to drive the reticle stage 14 in the X direction and to drive it in a small yaw rotation. The drive frame comprises a pair of parallel spaced magnetic track arms 24, 26, which arms 24, 25 are connected to each other by cross arms 28, 30 to form an open rectangle. In the preferred embodiment, since the drive frame 22 is supported to be movable on the base structure 12 by, for example, an air bearing 32, the drive frame is the desired principal of scan movement of the reticle stage on the base structure. Direction, that is, freely moving in the direction aligned with the longitudinal axis of the guide member 17. As used herein, 'one direction' or 'first direction' means that the reticle stage 14 or drive frame 22 moves forward or backward in the X direction along a line aligned with the longitudinal axis of the guide member 17. I mean.

1 and 5, the guide member 17 extending in the X direction is the front and rear guide surfaces 17A, 17B substantially perpendicular to the surface 12A of the base structure 12. Has The front guide surface 17A faces the rectangular drive frame 22 and guides the air bearing 20 fixed to the inner side of the support bracket 18. The support bracket 18 is mounted on each end of the upper surface of the arm 24 parallel to the guide member 17 of the drive frame 22. Furthermore, since each support bracket 18 is formed in the shape of a hook, it crosses the guide member 17 in the Y direction, and has a free end opposite to the rear guide surface 17B of the guide member 17. The air bearing 20 'is fixed inside the free end of the support bracket 18 and opposite the rear guide surface 17B. Therefore, the movement of each support bracket 18 in the Y direction is constrained by the guide member 17 and the air bearings 20 and 20 ', and can only move in the X direction.

Next, in the first embodiment of the present invention, the air bearing 32 fixed to the bottom surface of the four rectangular portions of the drive frame 22 is disposed between the surface 12A of the base structure 12 and the pad surface. It forms an air layer of constant gap (1 to several micrometers). The drive frame 22 is supported from the surface 12A by the air layer and supported vertically (Z direction). As will be described later in detail, in FIG. 1, the carrier / follower 60 positioned on the upper portion of the long arm 24 is supported by the bracket 62 with respect to both sides 17A, 17B of the guide member 17. It is supported in the transverse direction (Y direction) by the bearings 66A and 66B, and is supported in the vertical direction (Z direction) by the air bearing 66 on the surface 12A of the base structure 12. Therefore, the carrier / follower 60 is positioned so that it does not come into contact with any part of the drive frame 22. Therefore, the drive frame 22 is guided laterally by the guide member 17 on the base surface 12A, and moves only in one straight line X direction.

Next, the structures of the reticle stage 14 and the drive frame 22 will be described with reference to FIGS. 1 and 2. The reticle stage 14 includes a main body 42 in which the reticle 44 is positioned above the opening 46. The reticle body 42 includes a pair of opposing sides 42A, 42B and is positioned or lifted above the base structure 12 by, for example, an air bearing 48. A plurality of interferometer mirrors 50 provided on the main body 42 of the reticle stage 14 work in conjunction with the laser interferometer position sensing system 15 (see FIG. 6) to move the reticle stage 14 as desired. Determine the proper position of the stage supplied to the position control system 16 to indicate an appropriate drive signal for the.

Basic movement of the reticle stage 14 is achieved by means in the form of a first electromagnetic drive assembly or separate drive assemblies 52A, 52B on each opposing side 42A, 42B. The drive assemblies 52A, 52B include drive coils 54A, 54B fixedly mounted to the sides 42A, 42B of the reticle stage 14, respectively, which drive coil arm of the drive frame 22. It cooperates with each magnet orbit 56A, 56B on (24, 26). In a preferred embodiment of the present invention, the magnet coil is mounted on the reticle stage and the magnet is mounted on the drive frame 22, but the arrangement of these elements of the electromagnetic drive assembly 52 can be reversed.

Here, the structure of the reticle stage 14 will be described in more detail. As shown in FIG. 1, the stage main body 42 is provided so that movement to a Y direction is free in the rectangular space inside the drive frame 22. As shown in FIG. The air bearings 48 fixed below each of the four corners of the stage body 42 create very little air gap between the pad surface and the base surface 12A to lift the entire stage 14 from the surface 12A. Support it. This air bearing 48 is preferably mounted in a pre-loaded type with a recess for vacuum suction on the surface 12A.

As shown in FIG. 2, a rectangular opening 46 is provided in the center of the stage main body 42 so that the projection image of the pattern formed on the reticle 44 is passed through. In order to allow the projected image to pass through the rectangular aperture 46 through the projection optical system PL (see FIG. 5) installed below the rectangular aperture, another aperture 12B is provided in the center of the base structure 12. The reticle 44 is mounted on the upper surface of the stage main body by the clamping member 43C protruding at four points around the rectangular opening 46, and clamped by vacuum pressure.

Next, the interferometer mirror 50Y fixed near the side 42B of the stage main body 42 near the arm 26 has a vertical reflecting surface long in the X direction, and the length of the vertical reflecting surface is in the X direction. Slightly longer than the movable stroke of stage 14, the laser beam LBY from the Y axis interferometer enters the reflection plane perpendicularly. In FIG. 2, the laser beam LBY is bent at right angles by the mirror 12D fixed to the side of the base structure 12. As shown in FIG.

Next, referring to FIG. 3, which is a partial cross-sectional view of the line 3-3 ′ of FIG. 2, the laser beam LBY incident on the reflecting surface of the interferometer mirror 50Y is mounted on the clamping member 42c ( It is located on the same plane as the bottom surface (the surface on which the pattern is formed). 3 also shows an air bearing 20 on the end side of the support bracket 18 opposite the guide surface 17B of the guide member 17.

Referring again to FIGS. 1 and 2, the laser beam LBX1 from the X1-axis interferometer is incident and reflected on the interferometer mirror 50X1, and the laser beam LBX2 from the X2-axis interferometer is incident and the interferometer mirror 50X2. Reflected in the phase. These two mirrors 50X1 and 50X2 are composed of corner tubular mirrors, and even if the stage 14 rotates unevenly, this mirror ensures that the incident and reflective axes of the laser beam are always parallel in the XY plane. do. In addition, the block 12C of FIG. 2 is an optical block such as a prism for directing the laser beams LBX1 and LBX2 to the mirrors 50X1 and 50X2, respectively, and is fixed to a part of the base structure 12. The block corresponding to the laser beam LBY is not shown.

In Fig. 2, the distance BL in the Y direction between the centerlines of the two laser beams LBX1 and LBX2 is the length of the reference line used to calculate the yaw rotation amount. Therefore, the value obtained by dividing the difference between the measured value (ΔX1) in the X direction of the X1-axis interferometer and the measured value (ΔX2) in the X direction of the X2-axis interferometer by the length of the reference line BL is in a very small range. Approximate value of yaw rotation. In addition, half of the sum of DELTA X1 and DELTA X2 represents the X coordinate position of the entire stage 14. This calculation is done by a high speed digital processor in the position control system 16 shown in FIG.

Further, the center line of each of the laser beams LBX1 and LBX2 is set on the same surface as the surface on which the pattern is formed on the reticle 44. As shown in FIG. 2, the extension line of the line GX and the extension line of the laser beam LBY intersect half the space between the centerlines of each of the laser beams LBX1 and LBX2 intersect at the same plane on which the pattern is formed. 1, the optical axis AX (see FIGS. 1 and 5) also intersects at this intersection. In FIG. 1, a slit-shaped irradiation field ILS comprising an optical axis AX is shown on the reticle 44, and the pattern image of the reticle 44 is on the photosensitive substrate via the projection optical system PL. Scanned and exposed.

Furthermore, as shown in Figs. 1 and 2, two rectangular blocks 90A and 90B are fixed to the side 42A of the stage main body 42. These two blocks 90A, 90B are for receiving the Y direction driving force from the second electromagnetic actuator 70 mounted to the carrier / follower 60. This will be described later in detail.

The drive coils 54A and 54B fixed to both sides of the stage main body 42 are formed flat and parallel to the XY plane, and pass without any contact through the magnetic flux space in the slots extending in the X direction of the magnet tracks 56A and 56B. do. The assembly of the drive coil 54 and the magnet track 56 used in the present embodiment is a commercially available general-purpose linear motor that is commercially available and has no relation to the presence or absence of a rectifier.

Here, considering the actual design, the moving stroke of the reticle stage 14 is the size of the reticle 44 (if the reticle is removed from the irradiation optics to exchange the reticle with the amount of movement required when scanning for exposure). Is largely determined by the amount of movement required. In this embodiment, when using a 6 inch reticle, the moving stroke is approximately 30 cm.

As described above, the drive frame 22 and the stage 14 are independently supported on the base surface 12A while at the same time magnetic and reaction forces are exerted on each other in the X direction only by the linear motor 52. . For this reason, the law of momentum conservation holds between the drive frame 22 and the stage 14.

Next, if the weight of the entire reticle stage 14 is approximately 1/5 of the total weight of the frame 22 including the support bracket 18, the 30 cm forward movement of the stage 14 in the X direction results in a drive frame 22. Let it move back 6 cm in the X direction. This means that the position of the center of gravity of the device on the base structure 12 is substantially fixed in the X direction. In the Y direction, heavy objects do not move. Therefore, the positional change of the center of gravity in the Y direction is also relatively fixed.

As described above, the stage 14 is movable in the X direction, but the movable coils 54A, 54B and the stators 56A, 56B of the linear motor 52 interfere with each other in the Y direction without the X direction actuator ( Crashes). Therefore, the characteristic components of the present invention, the carrier / follower 60 and the second electromagnetic actuator 70 are provided for controlling the stage 14 in the Y direction.

Next, their structures will be described with reference to FIGS. 1 to 3 and 5.

As shown in FIG. 1, the carrier / follower 60 is installed to be movable in the Y direction through the hook-like support bracket 62 across the guide member 17. Moreover, as shown in FIG. 2, the carrier / follower 60 is located above the arm 24 to maintain a predetermined space between the stage 14 (body 42) and the arm 24. . One end 60E of the carrier / follower 60 protrudes substantially inward (to the stage body 42) on the arm 24. The drive coil 68 (same shape as the coil 54) entering the slot space of the magnet track 56A is fixed inside this end 60E.

In addition, the bracket 62 supported by the air bearing 66A (see FIGS. 2, 3, 4A, 5) opposite the guide surface 17A of the guide member 17 is a guide member of the carrier / follower 60. It is fixed in the space between the 17 and the arm 24. Also shown in FIG. 3 is an air bearing 66 for supporting and supporting the carrier / follower 60 on the base surface 12A.

The air bearing 66B facing the guide surface 17B of the guide member 17 is also fixed to the free end of the support bracket on the side of the hook on the opposite side to the air bearing 66A, and the air bearings 66A and 66B. The guide member 17 is located in between.

As shown in Fig. 5, the carrier / follower 60 is arranged to maintain a predetermined space in the Y and Z directions with respect to the magnet raceway 56A and the stage body 42, respectively. A column rod CB supporting the base structure 12 on the projection optical system PL and the projection optical system PL is shown in FIG. 5. This arrangement is common for the projection aligner, since unnecessary movement of the center of gravity of the structure on the base structure 12 causes lateral movement (mechanical twist) between the column rod CB and the projection optical system PL. This results in image blur on the photosensitive substrate during exposure. Therefore, the advantage of the apparatus as in this embodiment is important that the movement of the stage 14 does not move the center of gravity on the base structure 12.

In addition, the structure of the carrier / follower 60 will be described in detail with reference to FIG. 4A. In FIG. 4A, the carrier / follower 60 is broken down into two parts 60A and 60B for better understanding. As shown in FIG. 4A, a drive coil 68 for moving the carrier / follower 60 itself in the X direction is fixed to the lower portion of the end 60E of the carrier / follower 60. In addition, the air bearing 66C is disposed to face the base surface 12A on the bottom surface of the end 60E, and serves to support the carrier / follower 60.

The carrier / follower 60 is supported in the Z direction by the following three points, namely, two air bearings 66 and one air bearing 66C, and the air bearings 66A, 66B) restricts the movement in the Y direction. Importantly in this structure, since the second electromagnetic actuator 70 is arranged in the back bracket back relationship with the support bracket 62, the stage 14 and the carrier / follower in the case where the actuator generates the driving force in the Y direction The reaction force in the Y direction between the 60s actively acts on the air bearings 66A and 66B fixed inside the support bracket 62. In other words, if the actuator 70 and the air bearings 66A, 66B are arranged in a line parallel to the Y axis in the XY plane, the carrier / follower 60 is mechanically deformed when the actuator 70 'is in operation. This helps to prevent the occurrence of unwanted stresses. In other words, this means that the weight of the carrier / follower 60 can be reduced.

As shown in FIGS. 2 and 4A and 4C, the magnet trajectory 56A in the arm 24 of the drive frame 22 provides magnetic flux to the drive coil 54A on the side of the stage body 42. At the same time, the magnetic flux is also provided to the drive coil 68 for the carrier / follower 60. The air bearings 66A, 66B, 66C are preferably vacuum preloaded. This is because the carrier / follower 60 becomes light. In addition to the vacuum preload type, a magnetic preload type is also available.

Next, referring to Figures 3, 4B and 5, a second actuator mounted on the carrier / follower 60 will be described. The second electromagnetic drive assembly in the form of a voice coil motor 70 consists of a voice coil 74 attached to the main body 42 of the reticle stage 14 and a magnet 72 attached to the carrier / follower 60. The stage 14 is moved in a small displacement in the Y direction in the moving plane of the stage 14 perpendicular to the long straight line movement in the X direction generated by the drive assembly 22. The positions of the coil 74 and the magnet 72 may be opposite to each other. A schematic structure of the voice coil motor (VCM) 70 is shown in Figs. 3 and 5, the detailed structure of which is shown in Fig. 4B. Shown in FIG. 4B is a cross-sectional view of VCM 70 taken in cross section in the horizontal plane indicated by arrow 4B in FIG. 5. In FIG. 4B, the magnet 72 of the VCM 70 is fixed on the side of the carrier / follower 60. The coil of the VCM 70 includes a coil body 74A and a support 74B, and the support 74B steadily extends across the two rectangular blocks 90A, 90B (XY). Plate perpendicular to the plane). The center line KX of the VCM 70 shows the direction of the driving force of the coil 74. When a current flows through the coil body 74A, the coil 74 is negative or negative in the Y direction depending on the direction of the current. It causes a positive movement and generates a force corresponding to the amount of current. In a commonly used VCM, since a ring-shaped damper or bellows is usually provided between the coil and the magnet, a gap is maintained between the coil and the magnet, but in the present embodiment, such a gap is formed in the carrier / follower 60. Since it is retained by the following movement, no support element such as damper or bellows is needed.

In this embodiment, the capacitance gap sensors 13A and 13B are provided as the position sensor 13 (see FIG. 6), as shown in FIG. 4B. In FIG. 4B, the capacitance sensor electrode is arranged to detect a change in the gap in the X direction between the sides of the rectangular blocks 90A and 90B facing each other in the X direction and the case 70 'side of the VCM 70. It is. Such a position sensor 13 can be disposed anywhere as long as it can detect a gap change in the Y direction between the carrier / follower 60 and the stage 14 (or the main body 42). In addition, the sensor form can be any one of optoelectronic, inductive, ultrasonic, or non-contact forms such as air micro systems.

The case 70 'of FIG. 4B is formed in the carrier / follower 60 and is disposed (spatially) so as not to contact any member on the reticle stage 14 side. In the gap in the X direction (scanning direction) between the case 70 'and the rectangular blocks 90A, 90B, the wider the gap on the sensor 13A side, the narrower the gap on the sensor 13B side. Thus, the difference between the gap value measured by the sensor 13A and the gap value measured by the sensor 13B is obtained by digital or analog operation, and the drive coil 68 for the carrier / follower 60 is provided. If a direct servo (feedback) control system that controls the drive current of the is designed using a servo drive control circuit that zeroes the gap difference, the carrier / follower 60 remains in constant space with the stage body 42. The following movement in the X direction is automatically performed. In addition, the indirect servo control system that controls the current flowing through the drive coil 68 by the operation of the position control system of FIG. 6 includes a stage 14 measured from an X-axis interferometer and a measured gap value obtained from only one sensor. By using the X coordinate position of, it can be designed without using the two gap sensors 13A, 13B differentially.

As shown in FIG. 4B, in the VCM 70, the gap in the X direction (non-excitation direction) between the coil body 74A and the magnet 72 is actually about 2-3 mm. Therefore, the following accuracy of the carrier / follower 60 with respect to the stage main body 42 is allowable at approximately ± 0.5 to 1 mm. This degree depends on the allowable rotation of the stage main body, and also on the line length in the KX direction (excitation direction) of the coil main body 74A of the VCM 70. Moreover, this degree may be substantially lower than the exact positioning degree (eg, ± 0.03 μm if the resolution of the interferometer is 0.01 μm) in the stage body 42 using the interferometer. This means that the servo system for the follower can be designed very simply and the cost of installing the follower control system is reduced. In addition, the line KX of FIG. 4B is set to pass through the center of gravity of the entire stage 14 on the XY plane, and each of the air bearings 66A, 66B provided inside the support bracket 62 shown in FIG. 4A. The center is also located on the line KX in the XY plane.

FIG. 4C is a cross-sectional view of a portion including the guide member 17, the carrier / follower 60, and the magnet trajectory 56A, taken in the direction of arrow 4C in FIG. 2. The arm 24 receiving the magnet raceway 56A is floated on the base surface 12A by the air bearing 32, and the carrier / follower 60 is mounted on the base surface 12A by the air bearing 66. Levitation support). At this time, the height of the air bearing 48 (refer FIG. 3 or FIG. 5) and the height of the air bearing 32 in the bottom surface of the stage main body 42 is 54 A of drive coils on the stage main body 42 side part. ) Is determined to be arranged while maintaining a gap of about 2-3 mm in the Z direction within the slot space of the magnet raceway 56A.

Each space in the Z and Y directions between the carrier / follower 60 and the arm 24 is hardly changed since they are all guided by the common guide member 17 and the base surface 12A. Furthermore, the part on the base surface 12A on which the air bearing 32 of the bottom of the drive frame 22 (arm 24) is guided and the base surface on which the air bearing 48 of the bottom of the stage body is guided ( Even when there is a height difference in the Z direction between the parts on 12A), if this difference is precisely constant within the moving stroke range, the gap in the Z direction between the magnet track 56A and the drive coil 54A is also kept constant. .

In addition, since the drive coil 68 for the carrier / follower 60 is originally fixed to the carrier / follower 60, the gap which is fixed at 2-3 mm above and below the slot space of the magnet track 56A is fixed. Is arranged to maintain. The drive coil 68 has little shift in the Y direction with respect to the magnet trajectory 56A.

Cables 82 (see FIG. 2) are provided for transmitting signals to drive coils 54A, 54B on stage 14, coils 74 of voice coil motors, and coils 68 of carriers / followers. Since the cable 82 is mounted on the carrier / follower 60 and the guide member 17, it removes the drag force on the reticle stage 14. The voice coil motor 70 serves as a buffer by preventing external mechanical disturbances from being transmitted to the stage 14.

Next, the output of the cable will be described in detail with reference to FIGS. 2 and 4A. As shown in FIG. 2, a connector 80 (hereinafter referred to as a 'cable') connecting the wiring of the electrical system and the pipe of the pneumatic and vacuum system is one of the guide members 17 above the base structure 12. Mounted on the end. Connector 80 connects cable 81 from an external control system (including the control system of pneumatic and vacuum systems in addition to the electrical system control system shown in FIG. 6) to flexible cable 82. The cable 82 is also connected to the end 60E of the carrier / follower 60 and distributed as a conduit cable 83 of the pneumatic and vacuum system required for the electrical system wiring and the stage body 42.

As mentioned above, the VCM 70 acts to relieve the influence of the drag or drag of the cable, but sometimes this effect is in the unexpected direction between the carrier / follower 60 and the stage body 42. appear. In other words, the drag force of the cable 82 provides the rotating force of the guide surface or the base surface 12A of the guide member 17 to the carrier / follower 60, and the drag force of the cable 83 is the carrier / bell. It provides a force that causes the pupil 60 and the stage body to rotate relatively.

One of these moments, i.e., the component that shifts the carrier / follower 60, is not a problem, but the moment component that shifts the stage body in the X, Y, or Θ direction (the yaw rotation direction) is aligned and This can affect the degree of overlay. In the X direction and the Θ direction, the shift can be corrected by continuous driving by two linear motors 54A, 56A, 54B, 56B, and the shift in the Y direction can be corrected by the VCM 70. . In the present embodiment, since the weight of the entire stage 14 can be actually reduced, the response to the movement of the stage 14 by the VCM 70 in the Y direction and the response by the linear motor in the X and Θ directions Is extremely high in cooperation with a complete non-contact guideless structure. In addition, even when small vibrations (in microns) occur in the carrier / follower 60 and are transmitted to the stage 14 through the cable 83, such vibrations (several to tens of microseconds) are applied to the high response. Can be sufficiently eliminated.

4A shows how each cable is distributed to carrier / follower 60. Each drive signal to the drive coils 54A and 54B for the stage body 42 and the drive coils 74 for the VCM 70 and the detection signals from the position sensor 13 (gap sensors 13A and 13B) are connected to a connector ( 80 is provided via electrical system wiring 82A. Pressure gas and vacuum for each air bearing 48, 66 are provided from the connector 80 through the pneumatic system pipe 82B. On the other hand, the drive signal to the drive coils 54A, 54B is provided via the electrical system wiring 83A connected to the stage main body 42, and the compressed gas for the air bearing 48 and the vacuum for the clamping member 42C are provided. Is provided through the air hose 83B.

In addition, apart from that shown in FIG. 2, it is preferable to have separate lines for the air system for the air bearings 20, 20 ′, 32 of the drive frame 22. In addition, as shown in FIG. 4A, when the drag and vibration of the cable 83 cannot be prevented, the cable ( 83) is preferable. In this case, the moment can only be resolved by the VCM 70 with an extremely high response.

Next, referring to FIGS. 1, 2, and 6, the positioning of the reticle stage 14 is performed by first knowing the current position using the laser interferometer system 15. The drive signal is transmitted to the drive coils 54A and 54B of the reticle stage to drive the stage 14 in the X direction. Due to the difference in the driving force given to both side portions 42A and 42B of the reticle stage 14, a slight yaw rotation occurs in the reticle stage 14. The appropriate drive signal supplied to the voice coil 72 of the voice coil motor 70 generates a micro displacement in the Y direction of the reticle stage 14. When the position of the reticle stage 14 changes, the carrier / follower 60 follows the reticle stage 14 because the drive signal is transmitted to the carrier / follower coil 68. The resulting reaction force against the applied driving force moves the magnet track assembly or drive frame 22 in the direction opposite to the movement of the reticle stage 14, thereby substantially maintaining the center of gravity of the device. It is, of course, possible to fix the magnet track assembly 22 to the base structure 12 when the counter-weight or the recoil of the magnet track assembly 22 need not be included in the apparatus.

As described above, in order to control the stage apparatus according to the present embodiment, the control system shown in Fig. 6 is installed. This control system shown in FIG. 6 is described in more detail here. X1 drive coils and X2 drive coils composed of drive coils 54A and 54B of two linear motors, and Y drive coils composed of drive coils 72 of VCM 70 are installed in reticle stage 14, The drive coil 68 is installed in the carrier / follower 60. Each of these drive coils is driven in response to each drive signal SX1, SX2, SY1, SΔX from the position control system 16. The laser interferometer system for measuring the coordinate position of the stage 14 is a Y-axis interferometer for transmitting / receiving the beam LBY, an X1-axis interferometer for transmitting / receiving the beam LBX1, and a beam for receiving / receiving the beam LBX2. And an X2 axis interferometer, which transmits information IFY, IFX1, IFX2 about each axis direction to the position control system 16. The position control system 16 transmits two drive signals SX1 and SX2 to the drive coils 54A and 54B so that the difference between the position information IFX1 and IFX2 in the X direction becomes a set value, or in other words, The yaw rotation of the reticle stage 14 is maintained at the set value. Thus, needless to mention during exposure, when the reticle 44 is aligned on the stage body 42, the beams LBX1, LBX2, the X1-axis interferometer and the X2-axis interferometer, the position control system 16, and By the drive signals SX1, SX2, yaw rotation (in the Θ direction) positioning is always performed.

In addition, from the average value of the sum of the position information IFX1 and IFX2 in the X direction, the control system 16 which obtains the current coordinate position in the X direction of the stage 14 is provided with various instructions from the host CPU 16 'and Based on the information CD about each parameter, the drive signals SX1 and SX2 are transmitted to the drive coils 54A and 54B, respectively. In particular, when scanning exposure is in operation, it is necessary to linearly move the stage 14 in the X direction while correcting yaw rotation, so that the control system 16 is given the same or slightly different forces as necessary. Two drive coils 54A, 54B are controlled.

In addition, the positional information IFY from the Y-axis interferometer is also transmitted to the control system 16, and the control system 16 transmits the optimum drive signal SΔX to the drive coil 68 of the carrier / follower 60. Send. At this time, the control system 16 receives the detection signal Spd from the position sensor 13 which measures the space in the X direction between the reticle stage 14 and the carrier / follower 60, and the necessary signal ( Since the signal Spd is set to the above-described setting value and the tracking degree of the carrier / follower 60 does not have to be exact, the detection signal Spd of the control system 16 is not strictly calculated. do. For example, in the case where the movement is controlled by reading the positional information IFY, IFX1, IFX2 every 1 m second from each interferometer, the high speed processor in the control system 16 generates the detection signal Spd every hour. The current is sampled to determine whether the value is large or small compared to the reference value (confirmation of the direction), and if the deviation exceeds a constant value, a signal SΔX proportional to the deviation is transmitted to the drive coil 68. Can be. Furthermore, as described above, a control system 95 may be provided which directly servo-controls the drive coil 68 and also directly controls the following movement of the carrier / follower 60 without passing through the position control system 16. have.

As shown, since the movable stage apparatus has no attachment at all constraining the movable stage apparatus in the X direction, a small effect may cause the stage apparatus to drift toward the positive or negative X direction. This causes the collision of some parts when such an imbalance becomes excessive. Such influences include cable forces, inaccurate horizontality of base reference plane 12A, or friction between components. One simple way is to use a weak bumper (not shown) to prevent the drive assembly 22 from moving excessively. Another simple way is to cut off the supply of air to one or more air bearings 32, 20 used to guide the drive assembly 22 when the drive assembly reaches near the end of the stroke. . Such an air bearing can be operated when starting driving again in the opposite direction.

More precise methods require, by means of measurement (not shown), to monitor the position of the drive assembly and to provide the driving force to recover the precise position and maintain it. The measuring means is not required to be exact, but is about 0.1 to 1 mm. The driving force is obtainable by using another linear motor (not shown) attached to the drive assembly 22 or another motor coupled with the drive assembly.

Finally, the operation of the one or more air bearings 66, 66A, 66B of the carrier / follower 60 can be stopped to operate with the brake in the idle period of the stage 42. . When the coil 68 of the carrier / follower 60 is excited and the carrier / follower 60 is braked, the drive assembly is driven and accelerated. Thus, the position control system 16 monitors the position of the drive assembly 22. When the drive assembly is out of position, the drive assembly is repositioned to a significant extent using the drive coil 68 of the carrier / follower 60 intermittently.

In the first embodiment of the present invention, the drive frame 22 functioning as the counter-weight is provided to prevent the movement of the center of gravity of the entire apparatus and moves in the opposite direction to the stage main body 42. However, in the case of applying the structure of FIGS. 1 to 5 to an apparatus in which the movement of the center of gravity is not the main problem, the drive frames 22 may be fixed together on the base structure 12. In this case, it is possible to obtain some effects and functions, except for the problem with the center of gravity.

The present invention, ① long straight movement; A short straight line movement perpendicular to the long straight line movement; And (3) provide a stage that can be used for high-precision position and movement control with three degrees of freedom in one plane of micro-union rotation. The stage is isolated from the mechanical disturbance of the surrounding structure by using the electromagnetic force as the stage driving source. In addition, by using the structure for the guideless stage, a high control bandwidth is obtained. Due to these two factors, smooth and precise operation of the stage is achieved.

Description of the Preferred Embodiments

With the description of the embodiment illustrated in FIGS. 1 to 6 in mind, referring to FIGS. 7 and 8, in which preferred embodiments of the present invention are illustrated, where the last two digits of the reference numerals of each component are shown in FIGS. Corresponds to the two-digit reference number of each component of.

In Figs. 7 and 8, unlike the first embodiment described above, the drive frame serving as the counter-weight is eliminated, and each magnet trajectory 156A, 156B of the two linear motors is firm on the base structure 112. Is fitted. The stage main body 142 moving linearly in the X direction is disposed between the two magnet tracks 156A and 156B. As shown in FIG. 8, an opening 112B is formed in the base structure 112, and the stage main body 142 is disposed across the opening 112B in the Y direction. At both ends of the stage main body 142 in the Y direction, four preloaded air bearings are fixed on the bottom surface, whereby the stage main body 142 supports and supports the base surface 112A.

Further, according to this embodiment, the reticle 144 is clamped and supported on the reticle chuck plate 143 disposed separately on the stage body 142. A straight mirror 150Y for a Y axis laser interferometer and two corner mirrors 150X1, 150X2 for an X axis laser interferometer are mounted on the reticle chuck plate 143. The drive coils 154A and 154B are horizontally fixed with respect to the magnet tracks 156A and 156B at both ends in the Y direction of the stage main body 142, and the stage main body 142 is X by the above-described control subsystem. Make a straight line move in the direction and make it very small.

As is clear from Fig. 8, the right magnet trajectory 156B of the linear motor and the left magnet trajectory 156A of the linear motor are arranged to have a height difference in the Z direction between each other. In other words, the bottom surfaces of both ends in the long axis direction of the left magnet raceway 156 are disposed as high as a predetermined amount by the block member 155 with respect to the base surface 112A, as shown in FIG. The carrier / follower 160 in which the VCM is accommodated is disposed in the space below the highly arranged magnet trajectory 156A.

The carrier / follower 160 is supported and supported by a preloaded air bearing 166 (two points) on the base surface 112A 'of the base structure 112 one level lower. Also, two preloaded air bearings 164 opposed to the vertical guide surface 117A of the straight guide member 117 mounted to the base structure 112 are fixed to the side of the carrier / follower 160. This carrier / follower 160 is different from that shown in FIG. 4A according to the previous embodiment, and the drive coil 168 (FIG. 7) for the carrier / follower 160 has a bottom of the carrier / follower 160. It is fixed horizontally to a portion extending vertically from the surface, and is disposed without contact with any portion within the magnetic flux slot of the magnet track 156A. The carrier / follower 160 is arranged not to contact any part of the magnet trajectory 156A within the range of the movement stroke, and the VCM 170 precisely positions the stage main body 142 in the Y direction. Equipped with.

In addition, in FIG. 7, an air bearing 166 that supports and supports the carrier / follower 160 is provided below the VCM 170. In addition, the following movement of the carrier / follower 160 with respect to the stage main body 142 is also executed based on the sensing signal from the position sensor 13, as in the previous embodiment.

In the structure of the second embodiment configured as described above, since there is substantially no member functioning as a counter-weight, there is a inconvenience in that the center of gravity of the entire apparatus moves as the stage body 142 moves in the X direction. However, by following the stage main body 142 using the carrier / follower 160 so that there is no contact at all, it is possible to precisely position the stage main body 142 in the Y direction by the non-contact electromagnetic force by the VCM 170. It is possible. In addition, since the two linear motors are arranged to have different heights in the Z direction, there is an advantage that the vector sum of the force moments generated by each linear motor can be minimized at the center of gravity of the entire reticle stage. This is because the force moments of the respective linear motors cancel each other out substantially.

In addition, since the working axis in the longitudinal direction of the VCM 170 (line KX in FIG. 4B) is arranged to pass through the center of gravity of the entire structure of the stage not only in the Z direction but also on the XY plane, the driving force of the VCM 170 is staged. It is more difficult to give an unnecessary moment to the main body 142. In addition, since the method of connecting the cables 82 and 83 of the carrier / follower 160 can be applied in the same manner as in the first embodiment, the problem associated with the cable in the fully contactless guideless stage is also improved.

The same guideless principle may be employed in other embodiments. For example, in FIGS. 9 and 10, the stage 242 supported on the base 212 is driven in the long X direction by a single movable coil 254 moving within a single magnet trajectory 256. The magnetic track is firmly attached to the base 212. The center of the coil is disposed close to the center of gravity of the stage 242. To move the stage in the Y direction, a pair of VCMs 274A, 274B, 272A, and 272B are excited to provide acceleration in the Y direction. To control the yaw, the coils 274A, 274B are differentially excited by the control of the electronic subsystem. VCM magnets 272A, 272B are attached to the carrier / follower stage 260. The carrier / follower stage is guided and driven in the same manner as in the first embodiment described above. This alternative embodiment is available for the wafer stage. When used in a reticle stage, the reticle is positioned on either the coil 254 or the track 256 and needs to maintain the center of gravity of the stage 242 passing through the coil 254 and the track 256. If present, a compensation opening in stage 242 may be provided on the coil 254 and track 256 side opposite the reticle.

The advantages obtained from the above embodiments can be roughly summarized as follows. In order to maintain accuracy, the design of the carrier / follower does not cause a problem in the drag of the cable for the stage, since the cable connected to the stage follows the stage through the carrier / follower. The cable that connects the carrier / follower to the external device has a certain amount of drag, but because it is not directly connected to the carrier / follower acting as a buffer by preventing the transmission of mechanical disturbances to the stage, the stage It is not affected.

The counter-weight design also uses the law of momentum conservation to preserve the position of the center of gravity of the stage device at any movement in the long stroke direction of the stage. Such a device substantially eliminates any reaction forces between the stage device and the base structure on which the stage device is mounted, thereby facilitating high acceleration and at the same time minimizing the effects of vibration on the device.

In addition, as described above, since the stage is designed to perform a limited movement in three degrees of freedom, it is much simpler than a stage designed for full range of movement in all three degrees of freedom. In addition, unlike non-commutator-type devices, the present invention utilizes commercially available electromagnetic elements. The present invention is readily applicable to changes in stage size or stroke, as the present invention does not require special custom electromagnetic elements that increase difficulty in manufacturing as the size and stroke of the stage increases.

This embodiment with a single linear motor removes the second linear motor and performs yaw correction using two VCMs.

While the invention has been described in terms of preferred embodiments, the invention may take many different forms and should only be limited by the appended claims.

Claims (47)

A scanning type exposure apparatus for exposing a pattern to an object while the stage moves in the scanning direction, An exposure device for exposing the pattern to the object; A base structure in which the stage is movable; A first drive device for moving the stage in the scanning direction; And And a balance portion which is supported by the base structure so as to be movable and moves in a direction having a component opposite to the scanning direction in accordance with the movement of the stage. The method of claim 1, And the first driving device has a first portion connected to the stage and a second portion connected to the balance portion. The method of claim 2, And the first portion and the second portion do not contact each other. The method of claim 2, And the first portion comprises a coil member and the second portion comprises a magnet member. The method of claim 2, The movement of the stage and the balance unit is interlocked in accordance with the law of conservation of momentum. The method of claim 1, And said first drive device comprises a linear motor. The method of claim 1, And the stage is movable by a bearing on the surface of the base structure. The method of claim 7, wherein And the bearing is a non-contact bearing for supporting the stage in a non-contact state on the base structure. The method of claim 1, And a position detecting device for detecting the position of the stage. The method of claim 9, And the stage has a reflecting surface included in the position detecting device. The method of claim 10, And the reflective surface is a corner-cube mirror. The method of claim 9, And the position detecting device detects the position of the stage with respect to the scanning direction while the stage is moving. The method of claim 9, And the position detecting device detects the position of the stage in a direction different from the scanning direction while the stage is moving. The method of claim 9, And a control system for correcting yaw rotation of the stage based on a detection result by the position detecting device. The method of claim 14, And said control system is connected to said first drive device. The method of claim 1, And a second driving device for moving the stage in a direction different from the scanning direction. The method of claim 1, And the exposure device includes a projection system for projecting the pattern onto the object. The method of claim 17, And the stage is disposed above the projection system. The method of claim 17, And the projection system optically projects the pattern. The method of claim 1, And the exposure device holds a mask defining the pattern. The method of claim 20, And the stage holds the mask. The method of claim 1, And the balance portion operates without a drive source. The method of claim 8, And the non-contact bearing is an air bearing. The method of claim 9, And the position detecting device comprises an interferometer. The method of claim 1, And the stage includes an opening, and wherein the exposure device exposes the pattern to the object through the opening. In the scanning exposure method for transferring a pattern to an object, Moving the stage movably supported by the base in the scanning direction; Moving the balance part in the scanning direction so as to be movable by the base in accordance with the movement of the stage; And Exposing the pattern to the object while the stage is moving in the scanning direction. The method of claim 26, The stage is moved in the scanning direction by a first drive device having a first portion connected to the stage and a second portion connected to the balance portion. The method of claim 27, And the first portion and the second portion do not contact each other. The method of claim 27, And the first portion comprises a coil member and the second portion comprises a magnet member. The method of claim 27, Scanning exposure method, characterized in that the movement of the stage and the balance portion interlock in accordance with the law of conservation of momentum. The method of claim 27, And said first drive device comprises a linear motor. The method of claim 26, And moving the stage through a bearing on the surface of the base structure. The method of claim 32, And the bearing opposes the stage without contact with the base structure. The method of claim 26, And detecting the position of the stage by a position detection device. The method of claim 34, wherein And said stage has a reflecting surface included in said position detecting device. The method of claim 35, wherein And the reflective surface is a corner-cube mirror. The method of claim 34, wherein And the position detecting device detects the position of the stage with respect to the scanning direction while the stage is moving. The method of claim 34, wherein And the position detecting device detects the position of the stage in a direction different from the scanning direction while the stage is moving. The method of claim 34, wherein And correcting the yaw rotation of the stage based on the detection result by the position detection device. The method of claim 26, And moving the stage in a direction different from the scanning direction. The method of claim 26, And the exposure method is performed by an exposure device including a projection system for projecting the pattern onto the object. 42. The method of claim 41 wherein And the stage is disposed above the projection system. 42. The method of claim 41 wherein And the projection system optically projects the pattern. The method of claim 26, And the exposing device comprises a mask defining the pattern. The method of claim 44, And the stage holds the mask. The method of claim 26, And said balance portion is operated without a drive source. An object in which the pattern is transferred by the method according to claim 26.