JPH03178747A - Two-dimensional motor type stage device - Google Patents

Abstract

PURPOSE:To obtain an extremely high precision by arranging a number of permanent magnets into the form of a matrix on the surface of a yoke while alternately inverting their polarities, and supporting a stage on the upper surface thereof by means of an air bearing, and moving the stage by means of a Lorentz force generated by coil currents. CONSTITUTION:On the surface of a yoke 11 a number of permanent magnets 12 are arranged into the form of a matrix while their polarities are alternately inverted, and the coils 14a to 14f of a stage 13 are supported by an air bearing, etc., and disposed in a position where lines of magnetic force from the number of permanent magnets 12 are kept roughly perpendicular to the yoke 11. When currents are made to pass through the coils 14a to 14f Lorentz forces acting on the coils act roughly perpendicular to the coils and the lines of magnetic force, whereby the stage 13 is moved to a desired position on the surface of the yoke 11 and positioned. The two-dimensional stage of high precision is thus obtained.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a stage device, and particularly to a two-dimensional motorized stage device that moves an object within a two-dimensional plane.

[Prior Art] Conventionally, as a device for driving an object two-dimensionally, a Y-axis is mounted on an X-stage equipped with a servo motor and a ball screw that drive the object in the X-axis direction, which is one direction within a plane. An XY stage is known in which a Y stage is stacked with a servo motor and a ball screw for driving in the direction.

Ball screws cannot completely eliminate play and backlash, and in order to transmit the driving force generated by the servo motor to the object, it is necessary to pass through a power transmission mechanism or guide mechanism in the middle, and the generated driving force cannot be transmitted to the object. It is not possible to convey this to the object 100%.

Viewed from another perspective, this results in distortion, elastic deformation, etc. occurring in some mechanical member or the like.

Depending on such a mechanism, it is difficult to achieve positioning accuracy of approximately o, oi μm or less.

[Problems to be Solved by the Invention] It has been difficult to realize an ultra-precise XY stage of, for example, 0°01 μm or less, depending on the stage device using a servo motor and a ball screw as described above.

An object of the present invention is to provide a stage device suitable for realizing ultra-precise accuracy.

Another object of the present invention is to provide a stage device with a simple structure, no play, and excellent positional accuracy.

[Means for Solving the Problem] A large number of permanent magnets are arranged in a matrix on the yoke surface, and their polarities are alternately reversed. A coil fixed to the stage is placed at a distance such that the lines of magnetic force emanating from the permanent magnet are maintained approximately perpendicular to the yoke. When a current flows in the coil, the Lorentz force caused by the current acts in a direction approximately parallel to the stage surface. The load of the stage itself is supported by support means such as air bearings.

[Effect] If a large number of permanent magnets are placed on a yoke and a coil is placed in a position where the lines of magnetic force emitted from the magnets are maintained almost perpendicular to the yoke, when current flows through the coil, the Lorentz force acting on the coil The force acts in a direction approximately perpendicular to the coil and magnetic field lines, so there is little attraction or repulsion force acting on the stage, and most of the force acting on the coil is parallel to the stage surface. Furthermore, since this force acts directly on the coil, it is suitable for controlling the position of a stage to which the coil is attached or eclipsed.

[Embodiment] FIGS. 1A and 1B show an XY stage device according to an embodiment of the present invention, in which a large number of permanent magnets 12 are arranged in a grid on a yoke 11 made of a material with high magnetic permeability. In Figure 0, where is fixed, on the surface of the yoke 11, the magnet has an N pole or an S [! It is arranged so that it has. These magnetic poles are arranged so that the polarity is alternately reversed in both the X direction and the Y direction so that the S poles surround the upper and lower sides (Y direction) and the left and right sides (X direction) of one N pole.

For example, when the permanent magnets 12ij are arranged in a matrix, they are arranged so that when the sum of the number i of rows and the number j of columns is an even number, the S pole appears on the surface, and when the sum is an odd number, the Ni appears on the surface. .

As shown in FIG. 1(B), the yoke 11 is placed in a position floating from the support 10, and is driven in the X direction and Y direction by driving means 16a, 16b, 17 as shown in FIG. 1(A). driven in the direction.

In the figure, two drive means 16a and 16b are arranged in the Y direction, and one drive means 17 is arranged in the X direction.

Coils 14a, 14b, 14c, 14d, 14e, 1 are arranged so as to face the permanent magnet group 12ij on this yoke 11.
4f is placed. These coils 14a to 14f
is fixed to the stage 13, and the yoke 11 drives the stage 13.Although not clearly shown in FIG.
2, θX, θY are constrained in the direction of force and guided. The stage 13 is also restrained in the Z, θX, and θY force directions by means such as air bearings and sliding bearings. 14b, 14e, 1
4f is used for driving in the Y direction, and one set of coils 1.4c
, 14d are used for driving in the X direction. The number of these coils can be selected arbitrarily. Furthermore, as the material of the stage 11, a non-magnetic material such as ceramic or aluminum is used.

FIG. 1(B) is a sectional view taken along line IB-IB in FIG. 1(A), and shows coils 14a and 14b.

Coils 14a and 14b are permanent magnets 12ij of yoke 11.
It is supported at a height that allows it to be close enough to the Since the stage 13 is a non-magnetic material, it hardly affects the distribution of magnetic lines of force.

The force exerted on the stage will be explained with reference to FIGS. 2(A) to (D>).

A plurality of permanent magnets 12 are arranged on the surface of the yoke 11 with their polarities alternately reversed.

Since the yoke 11 has high magnetic permeability, lines of magnetic force are distributed within the yoke 11 from the north pole of the permanent magnet toward the south pole of the adjacent permanent magnet. In the upper part of a permanent magnet, only air and non-magnetic material are present, so the lines of magnetic force are not confined but open. The lines of magnetic force emanating from near the center of the magnet travel along the normal direction of the yoke like the lines of magnetic force 21c over a certain range.

As it approaches the end of the permanent magnet 12, the lines of magnetic force emanating from it curve like the lines of magnetic force 21e and move toward the magnetic pole of the opposite polarity of the adjacent permanent magnet.What should be noted here is that
At a position sufficiently close to the surface of the magnet 12, most of the magnetic lines of force are oriented in a direction close to the normal direction of the yoke 11. The windings of the coils 14a, 1.4b are arranged in a region where many of the magnetic lines of force are still in a direction close to the normal direction of the yoke. It is assumed that each coil has a rectangular shape along the X-axis and the Y-axis as shown in FIG. 1(A). It is assumed that the length of the short side is shorter than the length of the corresponding side of one permanent magnet, and the length of the long side is the length spanning adjacent permanent magnets.

With this arrangement, when a current I is passed through the coil 14a,
It can be approximated that the Lorentz force generated on the short side has a magnitude of f cusp BIQ and is oriented in a direction perpendicular to both the direction in which the current flows and the direction of the lines of magnetic force. That is, in the illustrated case, if the magnetic field lines are directed in the normal direction of the yoke 11, the force will be directed in a direction parallel to the surface of the yoke 11, thus generating a force approximately parallel to the stage 13 of the coil. In the case shown, the coil 14 can effectively drive the stage 13 in the XY plane.
Since the pitch of a matches the pitch between adjacent permanent magnets, the forces acting on the two sides of one coil placed on adjacent magnets are in the same direction.

Further, the adjacent coil 14b is also synchronized with the pitch of the permanent magnet, and exerts almost the same force in the same direction.

The stage 13 can be driven in a desired in-plane direction by monitoring the position of the stage 13, that is, the positions of the magnets 14a to 14r, and supplying current to the coils at the appropriate timing.

FIGS. 2(B) to 2(D) illustrate cases in which the stage is driven in the Y direction, the X direction, and the rotational direction around the Z axis, respectively. For example, in FIG. 2(B), four coils 14a, 14b, 14e, and 14f at both ends shown in FIG.
is used.

By simultaneously applying currents as shown in the figure to these coils, a force directed upward in the figure is generated.

This force drives the coil in the +Y force direction.

FIG. 2(C) shows a case where the stage 13 is driven in the X direction, using the coils 14c and 14d shown in FIG. A driving force in the direction can be generated.

As a result of this force, the stage 13 is driven in the +X direction.

In these examples, the generated resultant force is designed to pass through the center of gravity of the stage 13. Fig. 2 (4D) is designed to pass through the center of gravity of the stage 13. Fig. 1 (A) shows the case of driving in the rotational direction around the Z axis. Coils 14a, 14b, 1 shown in
Using four coils 4e and 14f, one set of coils L4a and 14b has a current in the direction of exerting a driving force in the -Y force direction, and one set of coils 14e and 14f exerts a driving force in the +Y force direction. Apply current in the direction to As a result, the stage 13 generates a rotational force around the Z axis.

The stage is made of non-magnetic material and the coil is coreless, so no magnetic force acts on the stage when no current is flowing through the coil, and even when current is flowing.
Unlike conventional magnetic circuits, which seek the position where the magnetic resistance is minimum, almost no attractive force acts between the stage and the yoke.

If the current is applied at the right time, only a force that is almost parallel to the yoke will act on the stage, so the force that holds the stage will be small.

Note that when the position of the coil moves and the direction of the lines of magnetic force changes, the force acting on the coil changes. There is also a region between the magnets where there are almost no lines of magnetic force in the normal direction of the yoke. Even if a current is passed through the coil in this region, only an attractive force or a repulsive force can be obtained.

FIGS. 3(A) and 3(B) are cross-sectional views for explaining the timing of stage drive.

In FIG. 3 (A>), the stage 13 is in a predetermined positional relationship with respect to the yoke 11, and the other yoke 11 is
It is movably supported on Q.

The position of the permanent magnet 12 on the yoke 11 and the position of the stage 13 are matched, and when current is passed through the coils 14a and 14b fixed to the stage 13, the position of the permanent magnet 12 on the yoke 11 is aligned to the right in the figure, parallel to the stage surface. The arrangement is such that a driving force is generated in the direction of . Here, when the stage is driven by supplying current to the coils 14a and 14b, the stage begins to move in a desired direction.

Now, consider moving the center position of the stage 13 from point P1 to point P2. Point P
If the large separation between 1 and point P2 is not an integral multiple of the gap g of the permanent magnet, but is at a halfway position, it will be difficult to apply an effective force to the coil near point P2. 11 position within the pitch m
By adjusting the distance O between the yoke 11 and the stage 13, the mutual position O between the yoke 11 and the stage 13 is adjusted. That is, as shown in FIG. 3 (B), the yoke 11 is driven so that the center point of the permanent magnet 12 is positioned at the desired target point P2. By applying current to the coils 14a and 14b when the stage 13 is brought to a standstill, a braking force can be exerted and the stage 13 can be stopped at a desired point P2.

Such stage drive and its current control are shown in Figure 4. In Figure 4, the horizontal axis represents time, and the vertical axis represents the stage position, yoke position, and current applied to the coil (two-dimensional motor thrust). shows.

At time t1, the relationship between the coil and the permanent magnet is in good condition, and the drive current i is applied.

This driving current is applied for a certain time Δt, but is then turned off. Then, the stage 13, which has been given a driving force for this time Δt, is translated by being given a driving force parallel to the stage surface. Start exercising. If the frictional force acting on the stage is O, the stage continues to move in translation even after the driving force is cut off, so its position changes linearly. This state is shown by the straight line portion of the stage position in FIG.

Yoke 1 is currently at target position P2 where the stage should be moved.
Consider the arrangement that 1 has. If this target position P
In step 2, if the relationship between the stage 13 and the yoke 11 is not suitable for effectively applying a driving force, the yoke 11 is driven to move the stage 13 to a position suitable for driving. This state is shown by the straight line of the yoke position in FIG.

Once the yoke has been driven to the target position, the yoke 11 is made to stand still. After that, when the stage 13 reaches the target position, since the yoke 11 is placed in a position suitable for driving, a current is applied to the coil to apply a braking force to the stage 13 and make the stage 13 stand still. This is illustrated by the negative pulse of the motor thrust in FIG.

Such driving of the yoke 11 is performed by driving means 16a, 16b, and 17 shown in FIG. 1(A). These driving means are performed via a driving force source such as a linear motor or piezoelectric element that generates displacement, and coupling means as shown in FIGS. 5(A) and 5(B).

That is, first, the stage 13 is placed at the optimal position on the yoke 1, and a drive pulse current is passed through a predetermined coil. With this initial drive, the stage 13 starts a translational movement with almost no resistance. The yoke 11 is displaced to a position suitable for braking the stage 13 at that position. When the stage 13 approaches the target position, the brakes are applied to stop the stage 13 at the target position.

The coupling means shown in FIG. 5(A) is a spherical hinge in which the radius is gradually reduced at l locations of a cylindrical portion that can be regarded as a rigid body, and a coupling portion is provided in which the cross section becomes thinner in a circular shape. The rigidity in the axial direction is high, and the rigidity in the direction orthogonal to the axis is low. Therefore, the force in the axial direction is transmitted to the object, but the hinge is driven by elastic deformation in the direction perpendicular to the axis. It is a coupling means that absorbs force.

FIG. 5(B) shows a coupling means that elastically deforms only in response to a driving force in one direction. In FIG. It is increasing again through the point. That is, this coupling member exhibits high rigidity against forces in the axial direction and vertical forces, or has low rigidity against forces in the horizontal direction.
Easily undergoes elastic deformation. That is, when this coupling member is used, only displacement in the horizontal direction in the figure is allowed in three-dimensional space. Note that these driving means 16
．． 17 is used to drive the yoke, but the support of the yoke is preferably provided by other means.

Various methods can be considered for supporting such a yoke member or stage member. FIG. 6 shows one example.

In FIG. 6, the yoke 11 is placed on a rigid member 23 via steel balls 21, 22 and is attracted to the rigid member 23 via a spring 24. In FIG.

That is, the yoke 11 is pressed against the rigid member 23 via the steel balls 20, 21, 22. Steel ball 20.21.
By the sliding engagement of 22, the yoke 11 performs a plane movement relative to the rigid member 23.

FIGS. 7(A) and 7(B) show an example of a stage support system.

In FIG. 7(A), the stage 13 has a larger area than the yoke 11. In FIG. Peripheral part 3 of this stage 13
Air pads 26, 27, 28 are provided at the locations. This air pad allows the stage 13 to
It is sucked at regular intervals for 3.

As shown in FIG. 8, the air pad 26.2728 is equipped with a permanent magnet 31 on the periphery, exerts an attractive force on the rigid member 23 made of a magnetic material such as iron, and blows out air in the center. A port 32 is provided to blow out air at a constant pressure and maintain a gap between the rigid member 23 and the air layer.

The narrower the gap, the stronger the pushing force of the air, and the pads are pushed up. The wider the gap, the less resistance to the air flow, and the magnetic attraction is stronger, attracting the pads.

That is, air pads 26, 27, 28 are stage 1
3 is attracted to the rigid member 23 and the distance is kept constant.The stage 13 has almost no resistance to its in-plane movement.The coils 14a to 14f are the permanent magnets 12.
When a force is exerted between the yoke 11 and a driving force parallel to the surface of the yoke 11, the stage 13 moves along the direction of the surface according to the driving force. At this time, air pads 26.27.
28 is almost r! Since it does not show J friction force, it is stage 1.
3 is prevented from being distorted due to frictional force.

Particularly when the stage 13 is arranged vertically, the support by the air pads 26, 27, 28 has better features than other support methods. That is, as the rigid member 23, a member with high rigidity that hardly causes elastic deformation, such as a rigid iron surface plate, can be selected. Since the air pad directly attracts the air pad while maintaining a certain distance from it, it is possible to accurately position the air pad. Stage 13 is this air pad 26.27.28
Since the stage is directly supported by the stage, there is almost no need to consider the deformation of the stage as a whole.

According to conventional air sliders and the like, since the air slider member that slides around the support column is provided, the load on the air slider increases and it is difficult to avoid deformation of the support column.

Since this deformation differs depending on whether the air slider is located at the upper or lower part of the support column, the positional accuracy differs depending on the position of the air slider member. The air pads 26, 27, 28 described above can prevent such changes in accuracy due to position.

Although the present invention has been described above with reference to the embodiments, it will be obvious to those skilled in the art that the present invention is not limited to these and that, for example, various modifications, improvements, combinations, etc. can be made.

FIG. 9 shows a vertical stage for SOR, in which SOR light travels horizontally through a duct within a base 31 and exits through a mask 37 provided at the opening of the duct. The semiconductor wafer 35 is placed on the wafer chuck 3 so as to receive this SOR light.
3. This wafer chuck 33 is fixed to the stage 13. The stage 13 is arranged in parallel between a pair of opposing bases 31, 32, and an air pad 26, 27, 28 equipped with a magnet is attached to one of the bases 31.
and is driven by a two-dimensional motor including a yoke 11, a permanent magnet 12, and a coil 14 relative to the other base 32. Air pads 26, 27, and 28 that support the stage 13 are connected to the permanent magnet 12 and the yoke 1.
Since the stage 13 is supported by a base 31 that is separate from the base 32 that supports the stage 13, space restrictions are relaxed and the size of the stage 13 can be reduced.

For example, a permanent magnet may be embedded in the yoke to make the yoke surface horizontal.

The coils provided on the stage are multilayered and the phase is reduced to 1/3.
By driving the yoke stage by shifting it pitch by pitch, the operating span of the yoke stage can be reduced. In this case, the size driven by the driving means can be reduced. In this case, it is also possible to balance the ups and downs force generated on the stage as a whole by the component in the normal direction of the magnetic lines of force.

[Effects of the Invention] As described above, according to the present invention, a highly accurate stage device with a novel structure for two-dimensionally driving an object is provided.

This effect is particularly great on a vertical stage where the stages are arranged vertically.

[Brief explanation of drawings]

1 (A>, (B)) show a stage device according to an embodiment of the present invention, in which FIG. 1 (A> is a plan view, FIG. 1 (B) is a sectional view, and FIGS. 2 (A) to ( D) is a diagram for explaining the force acting on the coil, FIG. 2(A) is a conceptual diagram for explaining the force acting on the coil, FIG. 2(B) is a diagram for driving in the Y direction, FIG. (
C) is drive in the X direction, FIG. (A) is a diagram showing the initial state when driving starts, Figure 3 (B) is a diagram showing the braking state before stopping, and Figure 4 is a timing chart of driving, where the horizontal axis shows time and the vertical axis The axes indicate the stage position, yoke position, and motor thrust. FIGS. 5(A) and 5(B) are diagrams showing examples of coupling means,
Figure 5 (A> is a perspective view of the spherical hinge, Figure 5 (B) is 1
A perspective view of a directional hinge, FIGS. 6(A) and 6(B) are views showing an example of a yoke support system, FIG. 6(A) is a surface view, FIG. 6(B) is a plan view, 7(A) and 7(B) are diagrams schematically showing a two-dimensional motorized stage, FIG. 7(A) is a plan view, and FIG.
) is a sectional view, FIG. 8 is a schematic sectional view of the air pad, and FIG. 9 is a schematic surface diagram of the vertical stage for SOR. In the figure, 11 yoke 12 permanent magnet 13 stage 14 16, I 2 coil drive means initial position target position gap

Claims (4)

[Claims] (1) A yoke made of a material with high magnetic permeability and defining a two-dimensional plane, and a plurality of yokes arranged in a two-dimensional matrix on the yoke and having alternating polarities along the plane of the yoke. a permanent magnet, a stage made of a non-magnetic material placed close to the yoke, and fixed to the stage and wound parallel to the stage surface, the lines of magnetic force emanating from the permanent magnet being approximately perpendicular to the surface of the yoke. a two-dimensional motorized stage apparatus having a stage driving means including a plurality of coreless coils capable of magnetically coupling with the permanent magnets within a range of the present invention. (2) The two-dimensional motorized stage device according to claim 1, further comprising yoke driving means for driving the yoke within the two-dimensional plane by a distance greater than or equal to the distance between the elements of the two-dimensional matrix. (3) The two-dimensional motorized stage device according to claim 1, wherein the stage is levitated by an air pad using air pressure. (4), the two-dimensional plane of the yoke is a vertical plane, the air pad includes a magnet and is attracted by magnetic force;
The two-dimensional motorized stage device according to claim 3, wherein the two-dimensional motorized stage device is levitated by air pressure.