JP3715742B2 - Static pressure stage - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a static pressure stage using a magnet that supports a moving stage with respect to a surface plate and attracts the moving stage toward the surface plate in order to increase its support rigidity, and more particularly to a scanning exposure apparatus. As a suitable static pressure stage.
[0002]
[Prior art]
As a conventional exposure apparatus, a so-called stepper is known in which a substrate to be exposed such as a wafer is sequentially moved and stopped to repeat exposure.
FIG. 3 shows details of the wafer stage of the stepper, and FIG. 4 shows an exploded view of the wafer stage. In the figure, a Y yaw guide 2 is fixed on a base surface plate 1, and a Y stage 3 guided by the side surface of the Y yaw guide 2 and the upper surface of the base surface plate 1 is an air slide (not shown) on the base surface plate 1 in the Y direction. It is slidably supported by. The Y stage 3 is mainly composed of two X yaw guides 3a, a Y slider (large) 3b, and a Y slider (small) 3c. The Y slider (large) 3b is provided on the side surface and the lower surface. The side surface of the Y yaw guide 2 and the upper surface of the base surface plate 1 face each other through the illustrated air pad, and the Y slider (small) 3c faces the upper surface of the base surface plate 1 through an air pad (not shown) provided on the side surface. As a result, the Y stage 3 as a whole is slidably supported in the Y direction on the side surface of the Y yaw guide 2 and the upper surface of the base surface plate 1 as described above.
[0003]
On the other hand, an X stage 4 guided by the side surfaces of two X yaw guides 3a that are components of the Y stage 3 and the upper surface of the base surface plate 1 is provided so as to surround the Y stage 3 around the X axis. Are slidably supported by an air slide (not shown). The X stage 4 is mainly composed of four members, that is, two X stage side plates 4a, an upper and lower X stage top plate 4b, and an X stage bottom plate 4c. The X stage bottom plate 4c is interposed via an air pad 4d provided on the lower surface thereof. The two X stage side plates 4a face the upper surface of the base surface plate 1 and face the side surfaces of the two X yaw guides 3a, which are constituent members of the Y stage 3, through air pads (not shown) provided on the side surfaces. The lower surface of the X stage top plate 4b and the upper surface of the X yaw guide 3a, and the upper surface of the X stage bottom plate 4c and the lower surface of the X yaw guide 3a are not in contact with each other. As a result, the X stage 4 as a whole is slidably supported in the X direction on the side surfaces of the two X yaw guides 3a and the upper surface of the base surface plate 1 as described above. A workpiece holding mechanism (not shown) is provided on the top of the X stage top plate 4b so as to hold a workpiece such as a wafer. A not-shown square mirror is provided here, and the X and Y stages 4, 3 are provided. The position of can be measured accurately with a laser interferometer.
[0004]
As the driving mechanism, one multi-phase coil switching type linear motor is used for X driving and two for Y driving. The stators 6a and 7a are obtained by inserting a plurality of coils 6c and 7c arranged in the stroke direction into a frame, and the movers 6b and 7b are constituted by box-shaped magnet units. 7d is a magnet coupling plate, and 8 is a Y stator fixing member. Thrust is generated by selectively passing a current through the coils 6c and 7c of the stators 6a and 7a according to the positions of the movers 6b and 7b.
[0005]
In order to increase the rigidity of the air slide, it is necessary to keep the gap at about 5 μm. For this reason, as shown in the exploded view, the X stage 4 is composed of two pressurizing magnets 4e provided between the air pads. To be sucked into.
Similarly, the Y stage 3 is attracted to the Y yaw guide 2 by a not-illustrated pressurizing magnet on the side surface of the Y slider (large) 3b, and the unillustrated pressure is applied to the bottom surface of the Y slider (large) 3b and the bottom surface of the Y slider (small) 3c. It is attracted to the base surface plate 1 by a magnet.
[0006]
As these pressurizing magnets, as shown in FIG. 5, a plurality of strip-shaped magnet pieces 9 arranged in a square unit are used.
[0007]
[Problems to be solved by the invention]
By the way, it is desirable that the pressurizing magnet provided to maintain the air gap only exerts an attractive force in the direction opposite to the buoyancy direction of the air slide. There is a problem that a proportional resistance force is also generated.
[0008]
As a feature of the current stage configuration, the tilt posture of the X stage 4 is directly guided by the base surface plate 1. Therefore, the X stage 4 moves two-dimensionally while facing the base surface plate 1, and receives resistance proportional to the speed in both XY directions.
The Y stage 3 receives the resistance of the pressurizing magnet only in the Y direction.
[0009]
On the other hand, as the pressurizing magnet, a plurality of strip-shaped magnet pieces 9 as shown in FIG.
[0010]
The magnitude of the resistance is proportional to the product of the three of the speed, the length of the side perpendicular to the moving direction of the magnet unit, and the number of magnet poles counted in the moving direction.
In the configuration of FIG. 5, since the magnet unit is square, if the moving speed is the same in both the X and Y directions, the same resistance is generated.
[0011]
Even if there is a resistance proportional to these speeds, the stepper is exposed in a stopped state, so the resistance is zero at the time of exposure, and there was no problem in the stepper.
[0012]
Next, FIG. 6 shows an overall view of a scanning exposure apparatus which is one of the next generation exposure apparatuses.
In FIG. 6, the surface plate 1 is supported from the floor (or the ground) 30 through the vibration isolation means 31. On the surface plate 1, a wafer stage 33 that is movable in the XY plane is provided, and a reduction projection optical system 35 is fixed via a lens barrel support member 34. A reticle stage base 36 is provided above the support member 34, and a reticle stage 37 that can scan the reticle stage base 36 along the guide in one axial direction is provided. Illumination system 38 for applying exposure energy to the wafer through the reticle is shown in broken lines. 41 is an outer cylinder of the optical system 35, and 42 and 43 are interferometer standards.
[0013]
In this apparatus, only a rectangular partial area of the reticle pattern is illuminated. Therefore, in order to expose the whole, the wafer stage 33 and the reticle stage 37 are synchronously scanned at a speed ratio equal to the reduction magnification of the optical system 35 and exposed during scanning. The wafer stage 33 is an XY stage. During exposure, the wafer stage 33 is controlled so that an axis parallel to the axis of the reticle stage 37 is scanned and the other axis is stationary.
[0014]
There is also a system shown in FIG. 7 as an improved type.
The projection optical system 35 supported by the lens barrel surface plate 45 is mechanically separated from the wafer stage surface plate 46 and directly supported by the vibration isolation means 31 from the floor 30. For this reason, the projection optical system 35 and the interferometer reference have an advantage that the vibration from the wafer stage 33 is not transmitted and the mechanical deformation and vibration of the optical system 35 and the interferometer references 42 and 43 can be extremely reduced.
[0015]
Further, the wafer stage surface plate 46 is directly supported from the floor 30 without the vibration isolation means 31 interposed therebetween. For this reason, there is an advantage that the swinging back of the surface plate 46 due to the reaction force when the wafer stage 33 is accelerated / decelerated is extremely small and the stopping accuracy is improved and the establishment time is shortened.
[0016]
In such a system, since exposure is performed during scanning, the running resistance unevenness and absolute value generated during scanning become new problems in the scanning direction.
[0017]
Unevenness of running resistance occurs as a result in combination with the drive system. For example, it occurs when a linear motor of a type that switches a plurality of coils is used in the drive system. In this type of motor, the thrust constant changes periodically depending on the position. Therefore, when driving at constant current, even if the resistance from the magnet is constant, the periodic unevenness of the thrust constant acts as the resistance unevenness as it is, and the exposure accuracy in the scanning direction is lowered. Since the magnitude of this unevenness is proportional to the absolute value of the resistance generated by the magnet, it is necessary to reduce the absolute value of the resistance of the magnet to reduce this.
[0018]
Further, if the absolute value of the running resistance is large, extra thrust is required to overcome this, and the heat generation of the drive system increases or the cooling system for removing the heat generation becomes large.
[0019]
The present invention has been made in view of the problems in the above-described conventional example, and an object of the present invention is to provide a static pressure stage in which the thrust resistance of the pressurizing magnet is small.
[0020]
[Means for solving problems]
In order to achieve the above object, the static pressure stage of the present invention is a static pressure stage used in an exposure apparatus that performs exposure during scanning, and is arranged along a first guide provided on a surface plate. A first stage that can be moved in the first direction and a second guide provided on the first stage, and a second direction that intersects the first direction on the surface plate. A second stage that is movable in the first direction along with the movement of the first stage, and the first and second stages that float the first and second stages from the surface plate, respectively. comprising a fluid static pressure applying means, and first and second preloading magnet sucking toward the first and respectively the platen a second stage, said one of said first and second directions in static pressure stage to be set as the scanning direction, before Second preload magnet and having a magnet unit formed by arranging a short rectangular shape a plurality of strip-type magnet pieces longer the scan direction perpendicular to the direction in the scan direction [0021]
In preferable embodiment of this invention, the length of each magnet piece which comprises the said magnet unit is the same length as the long side of this magnet unit. That is, this magnet unit is not divided in the long side direction, but is divided into a plurality of pieces only in the short side direction. Further, a second magnet unit having the same shape as the magnet unit can be used as the first pressurizing magnet. However, the second magnet unit is arranged so that its long side faces the first direction regardless of whether the scanning direction is the first direction or the second direction.
[0022]
As the scanning type exposure apparatus to which the present invention is applied, for example, the one shown in FIG. 6 or FIG. 7 can be used.
[0023]
[Action and effect]
In a static pressure stage for a scanning exposure apparatus, a pressurizing magnet unit is configured by arranging a plurality of rectangular magnet pieces in a one-dimensional manner, and the length of a side perpendicular to the scanning direction is parallel to the scanning direction of the overall shape of the configured magnet unit. The rectangle is shorter than the length of each side, and the scanning direction is perpendicular to the direction along the rectangular magnet pieces (short direction), that is, the longitudinal direction of the rectangular magnet pieces is parallel to the scanning direction. The magnet unit is arranged to be included. Thereby, the running resistance in the scanning direction due to the thrust force of the pressurizing magnet can be reduced, and the running resistance unevenness can be reduced and the exposure accuracy can be improved. In addition, as a result of the reduction in running resistance, heat generation is also reduced, which also contributes to improvement in exposure accuracy.
[0024]
【Example】
Embodiments of the present invention will be described below with reference to the drawings.
First embodiment FIG. 1 is a diagram for explaining a first embodiment of the present invention, and X stage 4 and Y stage 3 with X as a scanning direction and Y as a step direction as viewed from below. It is. In this embodiment, the components of the stage are the same as those in FIGS.
[0025]
The pressurizing magnet 4e of the X stage 4 is configured such that the overall shape of the magnet is a rectangle in which the length of the side perpendicular to the scanning direction (X direction) is shorter than the length of the side parallel to the scanning direction. Further, although the number of poles of the magnet is two, the direction along which the rectangular magnet pieces are arranged (the short side direction of the magnet pieces) and the scanning direction are orthogonal to each other.
[0026]
As described above, the absolute value of the resistance is proportional to the product of the three of the scanning speed, the length of the side perpendicular to the scanning direction of the magnet unit, and the number of poles of the magnet counted in the scanning direction.
[0027]
Therefore, in order to reduce the absolute value of resistance, it is sufficient to reduce these three. However, the scan speed cannot be reduced from the viewpoint of throughput. Therefore, the length of the side perpendicular to the scanning direction of the magnet unit and the number of magnet poles counted in the scanning direction are reduced. As shown in FIG. 1, the shape of the magnet unit 4e is a flat rectangle and its short side is arranged perpendicular to the scanning direction, so that the length of the side perpendicular to the scanning direction of the magnet unit is greatly reduced compared to the conventional example. . Further, the number of poles of the magnets counted in the scan direction is reduced by arranging the direction along which the two-pole magnets are aligned at right angles to the scan direction. Due to this synergistic effect, the resistance of the X stage 4 during scanning in the example of FIG. There is no particular need for the number of poles of the magnets from the viewpoint of reducing the resistance, and it is only necessary that the direction along which the magnets are aligned and the scanning direction be arranged at right angles, regardless of whether they are 6 poles or 10 poles. When an attempt is made to construct a flat rectangular unit as a whole as in the example, it is advantageous that the number of poles is smaller for reasons of machining and assembly of the magnet.
[0028]
On the other hand, the magnet unit 3e of the Y stage 3 is not different from the conventional example. This is because in this embodiment, only the X stage is scanned at the time of scanning, and the Y stage is stationary, so that no special measures need to be taken for the Y stage magnet unit.
[0029]
However, in the case of the X scan Y step as shown in FIG. 1, heat generation at the step of the Y stage 3 is reduced by arranging the direction along the rectangular magnet and the step direction at right angles to each other in the magnet of the Y stage 3. There is a merit. This merit becomes even more prominent when the overall shape of the magnet unit is a flat rectangle whose short side is perpendicular to the step direction.
[0030]
Second Embodiment FIG. 2 is a diagram for explaining the second embodiment, and shows the X stage 4 and the Y stage 3 as viewed from below, where Y is the scanning direction and X is the step direction.
In this embodiment, the X stage 4 and the Y stage 3 are integrally scanned during scanning. Therefore, both the magnet unit 4e of the X stage 4 and the Y stage magnet unit are configured such that the length of the side perpendicular to the scanning direction is a rectangle shorter than the length of the side parallel to the scanning direction . The number of poles of the magnet is two, but the direction along the rectangular magnet and the scanning direction are orthogonal to each other. The reason and advantage of the configuration of the magnet unit are exactly the same as in the first embodiment.
[0031]
【The invention's effect】
As described above, according to the present invention, it is possible to improve the overlay accuracy when combined with a multiphase motor, reduce the scan resistance due to the thrust force of the pressurizing magnet, and further reduce the heat generation of the motor and the like. it can.
[Brief description of the drawings]
FIG. 1 is a bottom view of a wafer stage according to a first embodiment of the present invention.
FIG. 2 is a bottom view of a wafer stage according to a second embodiment of the present invention.
FIG. 3 is an overall view of a wafer stage that is a conventional example and to which the present invention is applied.
4 is an exploded view of the wafer stage of FIG. 3. FIG.
FIG. 5 is a magnet unit diagram as a pressurizing magnet.
FIG. 6 is an overall view of a scanning exposure apparatus as an application target example of the stage of the present invention.
FIG. 7 is an overall view of another scanning exposure apparatus as an application target example of the stage of the present invention.
[Explanation of symbols]
1: base surface plate, 2: Y yaw guide, 3: Y stage, 3a: X yaw guide, 3b: Y slider (large), 3c: Y slider (small), 3e: pressurizing magnet, 4: X stage, 4a: X stage side plate, 4b: X stage top plate, 4c: X stage bottom plate, 4d: air pad, 4e: pressurizing magnet, 6a, 7a: stator, 6b, 7b: mover, 6c, 7c: coil, 7d: magnet Connecting plate, 8: Y stator fixing member, 9: magnet piece, 30: floor (or ground), 31: vibration isolation means, 33: wafer stage, 34: lens barrel support member, 35: reduction projection optical system, 36 : Reticle stage base, 37: Reticle stage, 38: Illumination system, 41: Outer cylinder, 42, 43: Interferometer reference, 45: Lens barrel surface plate.

Claims (9)

A static pressure stage used in an exposure apparatus that performs exposure during scanning, the first stage being movable in a first direction on the surface plate along a first guide provided on the surface plate ; The first stage can be moved along the second guide on the first stage in a second direction intersecting the first direction along the second guide and the first stage is moved. A second stage movable also in the direction of the first, second and second fluid static pressure applying means for floating the first and second stages from the surface plate, respectively, and the first and second stages In the static pressure stage, wherein one of the first and second directions is set as the scanning direction . the scan multiple strip-type magnet pieces preload magnet Static pressure stage, characterized in that it comprises a magnet unit formed by arranging a short rectangular shape long in the scanning direction and the direction perpendicular to the direction.   2. The hydrostatic stage according to claim 1, wherein the length of each magnet piece constituting the magnet unit is the same as the long side of the magnet unit. The second direction is the scanning direction, the second the first pressurization magnet made by arranging a long rectangular shape in short the scanning direction perpendicular to the direction in a plurality of strip-type magnet pieces to the scan direction The static pressure stage according to claim 1, further comprising: a magnet unit. Wherein the first direction is a scanning direction, the second the first pressurization magnet made by arranging short rectangular shape long in the scanning direction perpendicular to the direction in a plurality of strip-type magnet pieces to the scan direction The static pressure stage according to claim 1, further comprising: a magnet unit.   The hydrostatic stage according to claim 3 or 4, wherein the length of each magnet piece constituting the second magnet unit is the same as the long side of the magnet unit.   6. The surface plate is installed on a floor via vibration isolation means, and a projection optical system and a reticle stage constituting the scanning exposure apparatus are mounted on the surface plate. The static pressure stage according to any one of the above.   The surface plate is directly connected to the floor without the vibration isolation means, and the projection optical system and the reticle stage constituting the scanning exposure apparatus are mounted on another surface plate installed on the floor via the vibration isolation means. The static pressure stage according to claim 1, wherein the static pressure stage is provided.   The static pressure stage according to claim 1, wherein the fluid for generating the static pressure is air.   A static pressure stage used in an exposure apparatus that performs exposure during scanning, a stage that can move in a scanning direction on a surface plate, a fluid static pressure applying unit that floats from the surface plate, and the stage respectively. A magnet unit comprising a preload magnet that attracts toward a surface plate, wherein the preload magnet has a plurality of strip-shaped magnet pieces arranged in a rectangular shape that is long in the scanning direction and short in the direction perpendicular to the scanning direction. A static pressure stage characterized by comprising:

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