JP2908249B2 - Flat motor device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a planar motor, and more particularly, to a planar motor capable of driving a stage member on which an object is mounted within a relatively wide surface with high precision.

[0002]

2. Description of the Related Art In a stepper for semiconductor manufacturing, about 200
A wide movable range of mm square and a high driving resolution of 0.1 μm or less are required.

[0003] Conventional steppers are known to have a structure having a two-stage driving mechanism with a coarse moving part and a fine moving part, and a structure having a driving mechanism combining a ball screw and a servomotor. In the case of the former, a two-stage operation of coarse movement and fine movement is performed, so that a long time is required until the final stage is positioned. In addition, because of the hybrid structure, a plurality of actuators are used, and the mechanism becomes complicated mechanically.

[0004] As an example of the latter, first, a servomotor for driving in the x-axis direction, which is one direction in a plane, and an x-stage having a ball screw and the like are formed, and a servomotor for driving in the y-axis direction is formed thereon. An xy stage or the like in which a y stage provided with a ball screw and the like are stacked is known. According to the xy stage having such a configuration, a power transmission mechanism and a guide mechanism are necessary, and 100% of the power of the driving source is not transmitted to the object, and unnecessary distortion and elasticity of the mechanical members constituting the stage are required. Causing deformation. In order to reduce the amount of elastic deformation, there are many cases where the rigidity is generally increased by increasing the size of the mechanical structure, and therefore the weight increases.

On the other hand, an xy stage for laser processing includes
Usually, a movable range of 100 mm or more is required, and in particular, a precision of following a predetermined continuous trajectory and a driving resolution on the order of microns are required. The required drive resolution is lower than that of a stepper for manufacturing semiconductors, but on the other hand, the locus during movement becomes a problem due to the characteristics of laser processing. In a conventional xy stage in which two single-axis stages each composed of a servomotor and a ball screw are stacked, the torque ripple of the ball screw, the x-axis, and the y-axis
It is difficult to achieve high-accuracy trajectory following accuracy due to a difference in response speed between the axes.

[0006]

As described above,
With an xy stage or the like according to the conventional technology, it has been difficult to realize an ultra-precision stage device having a positioning accuracy of, for example, 0.01 μm or a stage device having a high-accuracy trajectory tracking accuracy.

An object of the present invention is to provide a planar motor device as a driving method suitable for realizing a stage device having a small, ultra-precise positioning accuracy and a high-accuracy trajectory tracking accuracy, for example.

[0008]

According to the planar motor device of the present invention, a stage member for mounting an object is moved within a predetermined movable area within a predetermined plane relative to a reference support member. A planar motor device for moving, wherein a plurality of equivalent permanent magnets attached to one of the stage member and the support member and generating a magnetic flux in a direction substantially perpendicular to the predetermined surface are alternately polarized. A plurality of magnet rows arranged in a straight line so as to appear, a yoke connecting the plurality of permanent magnets of the magnet row, and a stage member and the other of the support member facing each of the plurality of magnet rows. The magnet is engaged with the magnetic flux, and the length in a direction substantially orthogonal to the arrangement direction of the opposed magnet rows is formed longer than the width of the opposed magnet rows, and is substantially parallel to the arrangement direction of the opposed magnet rows. Axis direction A plurality of coil groups configured to include a plurality of coils to perform, when the stage member is in the movable region, the plurality of magnet rows, the coil group facing the magnet row, always They are arranged to cross each other.

Further, the plurality of magnet arrays may include at least two magnet arrays arranged in mutually different directions.

[0010]

A magnet array long in one direction and a coil group composed of a plurality of coils having an axial direction along the arrangement direction of the magnet arrays are arranged to face each other, and a predetermined current is applied to the coil group to thereby form the magnet array. A force can be generated in the arrangement direction. This force causes the magnet row to move in the arrangement direction. Since this force is generated as long as the magnet array and the coil group face each other, the magnet array can be driven in parallel by its length.

Further, at least two magnet rows arranged in mutually different directions are provided, and a coil group opposed to each magnet row always intersects with the magnet row in a range where each magnet row is driven in parallel. By doing so, it is possible to secure a wide movable area in a plane.

[0012]

FIG. 1 is a schematic view of a planar motor device according to an embodiment of the present invention. FIG. 1A is a plan view showing a positional relationship between a coil and a permanent magnet. FIG. 1B is a schematic side view showing the positional relationship between the permanent magnet and the coil.

As shown in FIG. 1A, an x-axis direction, a y-axis direction, and a rotation direction θ around an axis perpendicular to the x-axis and the y-axis are set in the movable plane of the planar motor. The planar motor device has a linear motor structure 1 in the x direction as a basic unit.
3. It has linear motor structures 14 and 15 in the y direction.
In the x-direction linear motor structure 13, the x coils 9a1 and 9b1 are arranged in the direction in which the central axes are parallel to the x-axis and are arranged in the x-axis direction on the same central axis. Further, the x coils 9c1 and 9d1 are replaced by the x coils 9a1 and
It is arranged on the same central axis as 9b1 and at a predetermined distance from the x coil 9b1 in the x-axis direction.

X coils 9a1, 9b1, 9c1, 9d
Numerals 1 are coils having the same characteristics, and are configured such that the length in the y-axis direction is longer than the length in the central axis direction. Note that the distance between the x coils 9b1 and 9c1 is half the axial length of each x coil.

Further, four x coils 9a1 and 9b
1, 9c1, 9d1 and a common non-magnetic core 1
2 are arranged. x coils 9a1, 9b1, 9c
1, 9d1, and x coils 9a2, 9b2, 9c2, 9d2, core 12, and x coils 9a3, 9b3, 9c3, 9d3, and core 12 configured similarly to the configuration of core 12
Are arranged side by side in the y-axis direction to form an x-drive coil group 9 that is long in the y-axis direction.

The x magnets 6a to 6p that generate a magnetic flux in a direction perpendicular to the plane of the paper are arranged side by side in the x-axis direction, forming an x magnet row 6 that is long in the x-axis direction. Each of the magnets 6a to 6p is longer in the y-axis direction than in the x-axis direction, and is a permanent magnet having the same characteristics.

In the arrangement shown, the x magnet row 6 is
In the x coils 9a2, 9b2, 9c2, 9d2, x
It intersects with the drive coil group 9. A similar configuration is adopted in the y-direction linear motor structures 14 and 15. That is, in the y-direction linear motor structure 14, the y coils 10a1, 10b1, 10c1, and 10d
1 are arranged in the direction in which the central axis is parallel to the y-axis and are arranged side by side in the y-axis direction on the same central axis. coil 1 for y
Half the axial length of each y coil is spaced between 0b1 and 10c1. Further, a common non-magnetic core 12 is arranged so as to penetrate the four y coils 10a1, 10b1, 10c1, and 10d1.

Y coils 10a1, 10b1, 10c
1, 10d1, y coils 10a2, 10b2, 10c2, 10d2 and core 12 and y coils 10a3, 10b3, 10c3, 10d3 configured similarly to core 12.
And the core 12 are arranged side by side in the x-axis direction to form a y-drive coil group 10 that is long in the x-axis direction.

The y magnets 7a to 7p that generate a magnetic flux in a direction perpendicular to the plane of the paper are arranged side by side in the y-axis direction to form a y-magnet row 7 that is long in the y-axis direction. Each of the magnets 7a to 7p is a permanent magnet that is longer in the x-axis direction than in the y-axis direction and has the same characteristics.

In the illustrated arrangement, the y magnet row 7 is
The portions of the y coils 10a2, 10b2, 10c2, and 10d2 intersect with the y drive coil group 10. The other y-direction linear motor structure 15 has the same configuration as the y-direction linear motor structure 14. That is, the y coil 1
1a1 to 11a3, 11b1 to 11b3, 11c1 to 1
1c3, the core 12, and the y magnets 8a to 8p are arranged so as to have the same configuration as the y-direction linear motor structure portion 14.
The y-drive coil group 11 and the y-magnet row 8 are configured.

The y drive coil groups 10 and 11 extend in opposite directions parallel to the x axis from one end of the x drive coil group 9 arranged parallel to the y axis. The y magnet rows 7 and 8 extend in the same direction parallel to the y axis from both ends of the x magnet row 6 arranged in parallel with the x axis.

The x and y magnet arrays 6, 7, and 8 arranged as described above are composed of x and y driving coil groups 9, 10, and 11 respectively.
Can be relatively moved in the xy plane as described later.

The magnet array 6 for x and the coil group 10 for y drive,
11 are substantially the same length, and the y magnet rows 7
The 8 and x drive coil groups 9 are configured to have substantially the same length. Therefore, the x magnet row 6 becomes x
When moving in the x-axis direction within a range intersecting the drive coil group 9, the y magnet arrays 7, 8 always intersect the y drive coil groups 10, 11, respectively. Similarly, the magnet rows 7, 8 for y
Move in the y-axis direction within the range intersecting with the y drive coil groups 10 and 11, respectively, the x magnet array 6 always intersects the x drive coil group 9.

Thus, even if the x and y magnet rows are moved by the length of the x magnet row 6 in the x-axis direction and by the length of the y magnet rows 7 and 8 in the y-axis direction, x And y magnet rows will always intersect the corresponding x and y drive coil groups.

FIG. 1A shows a case where the x and y drive coil groups each have three coils arranged in a direction orthogonal to the axial direction of each coil. However, the number of coils must be limited to three. There is no. For example, one coil formed long in a direction perpendicular to the axial direction may be used, or two or four or more coils may be arranged.

FIG. 1B is a schematic side view showing the relative relationship between the x magnet rows 6 arranged on the x drive coil group 9. X coils 9a2, 9b2, 9c on base 1
2, 9d2 is fixed, and the core 12 penetrates its axis. These x coils 9a2, 9b2, 9c2, 9
The x magnet row 6 is arranged above d2 via a gap 17 having a predetermined width.

The width (magnet pitch) of each x magnet is equal to the axial length of each of the x coils 9a2 to 9d2. Also, x
The interval between the use coils 9b2 and 9c2 is set to half the magnet pitch.

FIG. 1B shows a case where the x magnets 6c and 6d face the x coils 9a2 and 9b2, respectively. At this time, the right half of the x magnet 6e and the left half of 6d face the x coil 9c2, and the x coil 9d
2, the right half of the x magnet 6f and the left half of 6g face each other.

The x magnets in the x magnet row 6 are arranged so that their polarities are alternately reversed, and are fixed to the yoke 5 made of a material having high magnetic permeability. The yoke 5 is fixed to the stage member 3. By fixing the x and y coils to the base 1, heat generated from the coils can be released to the base. In addition, since the stage member 3 has no heat source, highly accurate positioning can be performed.

In the illustrated configuration, the x magnets 6c, 6
e and 6g have an N pole below and an S pole above, and the other x magnets 6d and 6f have an S pole below and an N pole above. Therefore, a magnetic path 16 is formed as shown by a dotted arrow in the figure,
Magnetic flux is distributed.

In the presence of such a magnetic flux, when a current flowing from the back of the drawing to the surface on the x magnet side is applied to the coil 9a2 and a current in the opposite direction is applied to the coil 9b2, the coil 9a2 is mainly driven. The current flowing on the magnet side interacts with the magnetic flux. Since the directions of the magnetic fluxes in these two coils are opposite to each other, a force in the same direction x is generated in both the coils that flow currents in opposite directions. x coils 9a2, 9b2
A force is also generated by a current flowing through the base 1 side surface of the x coil, but the magnetic flux linked to the base 1 side surface of the x coil is x
This amount is negligible compared to the magnetic flux linked to the surface on the side of the magnet for use.

Further, mutually opposite currents are applied to the x coils 9c2 and 9d2. Since the magnetic flux interlinking with the magnet-side surfaces of the x coils 9c2 and 9d2 are opposite to each other in the left half and the right half, the forces generated by the x coils 9c2 and 9d2 cancel each other. Therefore, the x magnet row 6 is driven in the x direction as a whole.

FIG. 2 shows the x coil 9a shown in FIG.
The relationship between the thrust in the x-direction and the displacement of the x-magnet array 6 in the x-direction when a constant current flows in each of 2 to 9d2 is shown. The horizontal axis represents the moving distance of the x magnet row 6 from the reference point. Here, l _p represents a magnet pitch. The vertical axis represents thrust on an arbitrary scale.

The thrust generated by the pair of x coils 9a2 and 9b2 and the thrust generated by the pair of x coils 9c2 and 9d2 have a phase shift of about 90 degrees. As shown in FIG. If it is a sine wave, the other will be a cosine wave. The thrust is proportional to the current flowing through the x coils 9a2 to 9d2.

The force generated by one set of the x coils 9a2 and 9b2 and one set of the x coils 9c2 and 9d2 can be expressed as follows.

[0036]

Fx _A = ki _xA cos (πx / l _p ) (1)

[0037]

Fx _B = ki _xB sin (πx / l _p ) (2) Here, Fx _A and Fx _B are x coils 9a2,
The thrusts in the x direction, i _xA and i _xB , generated by one set of 9b2 and one set of x coils 9c2 and 9d2 are one set of x coils 9a2 and 9b2 and one set of x coils 9c2 and 9d, respectively.
Current flowing in the second set, x is the displacement of x for magnet array 6, l _p is the magnet pitch, k denotes the thrust constant.

The current flowing through each coil is determined based on the displacement of the x magnet array 6 as follows.

[0039]

[Number 3] _{i xA = i r cos (πx} / l p) ... (3)

[0040]

[Number 4] _{i xB = i r sin (πx} / l p) ... (4) here, i _r denotes a target current.

At this time, the total thrust generated by the x coils 9a2 to 9d2 is

[0042]

[Number 5] becomes a _{Fx = Fx A + Fx B =} ki r ... (5).

As described above, by applying a predetermined alternating current to the x coils 9a2 to 9d2, a thrust proportional to the target current can be generated. Note that the x magnet row 6 is x
The x coils 9a1 to 9d1 or 9 of the driving coil group
Similar thrust can be generated when the vehicle crosses at positions a3 to 9d3.

Similarly, a thrust in the y-axis direction is generated between the y-drive coil group 10 and the y-magnet row 7 and between the y-drive coil group 11 and the y-magnet row 8. Can be.

FIG. 3 shows a driving mode of the planar motor device having the structure as shown in FIG. 3A shows an x translation mode, FIG. 3B shows a y translation mode, and FIG.
Indicates a θ rotation mode.

In FIG. 3A, a current is applied to the x driving coil group 9 of the x direction linear motor structure 13. For this reason, a force in the x direction is generated in the x magnet row 6 of the x direction linear motor structure unit 13 to drive the stage member in the x direction.

FIG. 3B shows the y translation mode. y drive coil group 1 for y direction linear motor structures 14, 15
An electric current is applied to generate 0 and 11 forces in the same direction.
Then, the same y-direction driving force is generated in the y-magnet rows 7 and 8 of the y-direction linear motor structures 14 and 15. Therefore, the stage member translates in the y direction.

FIG. 3C shows the θ rotation mode in the xy plane. A current is supplied to the y-direction linear motor structures 14 and 15 so that a force in the opposite y-direction is generated. For example, as shown in the drawing, a current is supplied to each y-driving coil group so that a force is generated in the −y direction in the y-direction linear motor structure 14 and in a + y direction in the y-direction linear motor structure 15. . When these parallel forces are generated in the opposite directions, the stage members supporting the y magnet arrays of the linear motor structures 14 and 15 rotate in the + θ direction in the xy plane.

When driving in the x direction as shown in FIG. 3A, a weak torque is generated in the θ direction because the position where the driving force is generated is shifted from the center of gravity of the stage member 3. At this time, the stage member can be translated in the x direction by generating a torque in a direction to cancel the torque by the y-direction linear motor structures 14 and 15.

As described above, the stage member 3 in the xy plane
, A thrust can be generated if the x and y drive coil groups and the corresponding x and y magnet rows intersect. Therefore, in the x-axis direction, it is possible to secure a movable range having a length obtained by subtracting the width of the x driving coil group 9 from the length of the x magnet row 6. Similarly, in the y-axis direction, the y drive coil group 1
It is possible to secure a movable range with a length reduced by the width of 0 and 11. Thus, it is possible to secure a large movable range in the xy plane.

The thrust acts in parallel on the x and y magnet rows 6, 7, 8 fixed to the stage member 3, respectively. Therefore, the length of the arm of the moment of thrust with respect to the center of gravity is constant regardless of where the stage member 3 is within the movable range. Therefore, control of each axis (x, y, θ) can be easily performed regardless of the position of the stage member 3.

Further, in the above-described embodiment, the case where the x and y coils are arranged in a two-phase structure displaced by １ ／ pitch has been described. However, an n-phase structure may be generally used. In the case of a linear motor having an n-phase structure, the coils of each phase may be shifted by 1 / n pitch.

In the above description, it has been assumed that each coil is fixed to the base, each permanent magnet is fixed to the stage member, and the stage can move freely in the xy plane. The force acting on the coil and the force acting on the permanent magnet are equal in magnitude and opposite in direction. Such a structure can be realized by, for example, supporting the stage in a xy plane with a roller or the like, but it is more preferable to use a bearing mechanism with low friction such as an air bearing as described below.

According to the structure in which the air bearing is combined so that the floating force of the air bearing acts in the opposite direction to the self-weight of the mechanical structure of the movable portion of the stage or the attraction force of a magnet or the like, the stage can be set at a predetermined height above the base. Hold on to
The robot can be freely moved in the xy plane.

FIG. 4 is a perspective view showing an xy stage device provided with a planar motor device. The base 1 has a flat guide surface 2 thereon, and the x drive coil group 9 and the y drive coil groups 10 and 11 are fixed on the guide surface 2 so as to be arranged as shown in FIG. I do.

On the guide surface 2 of the base 1, an air pad 4
The main stage 3 supported by is arranged. The air pad 4 has, for example, an air outlet on its lower surface, and floats on the guide surface 2 of the base 1 by blowing air. When a vertical stage such as an SOR aligner is used, a plane motion can be performed on a vertical plane by using a permanent magnet in parallel with the air pad.

A yoke 5 made of a material having high magnetic permeability such as iron is fixed to the lower surface of the main stage 3. On the lower surface of the yoke 5, x magnet rows 6 and y magnet rows 7, 8 are fixed so as to be arranged as shown in FIG.

The main stage 3 is levitated by the air pad 4 and driven by a combination of a coil and a magnet, so that a force can be applied directly to the main stage with almost no friction. For this reason, it becomes possible to prevent distortion and elastic deformation from occurring in the structural member. Further, the size of the entire apparatus can be reduced. In this way, a stage device capable of high-accuracy positioning is provided.

In the above embodiment, the case where one x-direction linear motor structure and two y-direction linear motor structures are provided has been described.
Two directional linear motor structures may be provided respectively.

FIG. 5 is a plan view showing the positional relationship between the x and y drive coil groups and the x and y magnet arrays when two x and y direction linear motor structures are provided.

The magnet rows 30, 31 for x and the magnet row 3 for y
2 and 33 are arranged in a rectangular or square shape such that each magnet row forms one side. x drive coil groups 40 and 41 and y drive coil groups 42 and 43
Are radially arranged parallel to the x-axis and y-axis directions, respectively. Each coil group and magnet row are fixed to a base and a stage member, respectively, as in the case of FIG. The positional relationship between the coil groups and the magnet rows in the direction perpendicular to the paper surface is the same as that in the case of FIG.

Magnet arrays 30 to 33 and coil groups 40 to 43
When the stage member is moved while maintaining the relative position such that the square formed at the center of the radially arranged coil groups 40 to 43 is included in the square surrounded by the magnet arrays 30 to 33, The coil groups 40 to 43 are configured to always intersect with the respective magnet rows 30 to 33.

By arranging the coils and the permanent magnets in this manner, the stage member can be used as the x and y magnet rows 30 to
A movable range of a rectangular size surrounded by 33 can be secured. Further, thrust is generated at two places in both the x-axis direction and the y-axis direction, so that the movement performance of the stage member can be improved.

In the above embodiment, the case where the coil group is fixed to the base and the magnet array is fixed to the stage member has been described. However, the configuration may be reversed. Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. For example, it will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

[0065]

As described above, according to the present invention,
By disposing a long permanent magnet array in a direction intersecting the length direction of the coil group in opposition to the long coil group in one direction, and supplying a controlled current to the coil group, the length of the magnet array is changed to the permanent magnet array. A directional force can be generated.

As long as the coil group and the permanent magnet row intersect, a force can be generated. Therefore, by providing two sets of the coil group and the permanent magnet array and disposing them in two different directions, a wide movable range can be secured.

[Brief description of the drawings]

FIG. 1 shows a planar motor device according to an embodiment of the present invention.
FIG. 1A is a plan view, and FIG. 1B is a side view.

FIG. 2 is a graph for explaining a force generated corresponding to FIG. 1 (B).

FIG. 3 is a plan view of the flat motor device for describing a drive mode of the flat motor device shown in FIG. 1;

FIG. 4 is a perspective view showing an xy stage device according to an embodiment of the present invention.

FIG. 5 is a plan view showing another configuration example of the planar motor device according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Base 2 Guide surface 3 Stage member (main stage) 4 Air pad 5 Yoke 6 Magnet row for x 7, 8 Magnet row for y 9 x Driving coil group 10, 11 Y driving coil group 12 Core 13 X direction linear motor structure Part 14, 15 Y direction linear motor structure part 17 Gap 30, 31 x magnet array 32, 33 y magnet array 40, 41 x drive coil group 42, 43 y drive coil group

────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-6-86594 (JP, A) JP-A-5-336730 (JP, A) JP-A-4-189436 (JP, A) 12657 (JP, A) (58) Field surveyed (Int. Cl. ⁶ , DB name) H02K 41/00-41/035

Claims (7)

(57) [Claims] 1. A planar motor device for moving a stage member on which an object is mounted within a predetermined movable area within a predetermined plane relative to a reference support member, wherein the stage member A plurality of permanent magnets attached to one of the support members and generating a magnetic flux in a direction substantially perpendicular to the predetermined surface, and a plurality of permanent magnets linearly arranged so that polarities alternately appear. A row, a yoke that couples the plurality of permanent magnets of the magnet row, and is mounted on the other of the stage member and the support member so as to face each of the plurality of magnet rows, and engages with the magnetic flux; The length in a direction substantially orthogonal to the arrangement direction of the opposing magnet rows is formed longer than the width of the opposing magnet rows,
And a plurality of coil groups including a plurality of coils having an axial direction substantially parallel to the arrangement direction of the opposing magnet rows, wherein the plurality of magnet rows are provided when the stage member is in the movable region. And a coil group opposed to each magnet row are arranged so as to always cross each other. 2. The planar motor device according to claim 1, wherein the plurality of magnet rows include at least two magnet rows arranged in mutually different directions. 3. The plurality of magnet rows are arranged along three sides of a rectangle, and the plurality of coil groups are radially arranged from one point in the rectangle in directions perpendicular to the three sides. The planar motor device according to claim 1 or 2, wherein: 4. The plurality of magnet rows are arranged in a rectangular shape, and the plurality of coil groups are radially arranged in a direction perpendicular to each side of the rectangle from one point in the rectangle. The planar motor device according to claim 1. 5. The plurality of coil groups include a plurality of cores arranged in parallel with each other and a plurality of coils arranged at a plurality of corresponding positions of each core, wherein the cores have different positions in the axial direction. The planar motor device according to any one of claims 1 to 4, which is suitable for multi-phase driving. 6. The flat motor device according to claim 1, wherein the stage member and the support member are connected via a flat guide mechanism. 7. The planar motor device according to claim 1, wherein the plurality of sets of coils are a plurality of sets of coils having a high magnetic permeability material core or a nonmagnetic material on a shaft.