JPH033741A - Stage movable support device - Google Patents

Abstract

PURPOSE:To support and move precisely and surely by supporting a stage consisting of a non-magnetic body and having an edge part with tapered face on the magnetic fluid holding it by a magnetic field in the gap between iron cores located at plural places of the edge part with the application of a magnetic field on the iron cores. CONSTITUTION:A stage 1 is a plate like needle formed from a non-magnetic material and when a magnetic field is applied by exciting an exciting coil 5 to the iron cores 3 of stage supporting means A, B, the apparent specific gravity of a magnetic fluid 2 existing at a gap part L becomes larger, the buoyancy onto the stage 1 is increased and it is floated. When a different mag netic field is applied to the iron core 3 in this case, a different buoyancy is acted on the A and B sides for the stage 1, the displacement force works in the positive or negative direction of an X axis on the stage 1 and it is moved in the X axis positive or negative direction. Consequently the strength of the current of the exciting coil 5 is varied for the exciting coil 15 of the support means A, B to enable the positional adjustment of the stage 1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a movable stage support device that can be applied to various devices such as semiconductor manufacturing equipment, inspection equipment, and precision machinery.

[Conventional technology]

2. Description of the Related Art In recent years, due to the development of ultra-large scale integrated circuits (VLSI) and the like, there has been an increasing demand for higher accuracy, higher speed, smaller size, and lighter positioning of objects. In addition, as a basic technology of biotechnology, we also provide manipulators for cell micromanipulation, tables and supports for measuring instruments, etc.
In order to slightly move a stage such as a moving table, an actuator that can be moved finely is required. Linear actuators are attracting attention for these linear movements.

2. Description of the Related Art Conventionally, stage movable support devices used in semiconductor manufacturing equipment, inspection equipment, etc. are currently configured to float the stage in the air for smooth movement.

[Problem to be solved by the invention]

However, the above-mentioned linear actuator has a moving stage,
In order to support, guide, or drive a stage such as a table, the device has a support controller, a guide controller, or a drive controller, respectively, which increases the number of parts of the device itself, making it complicated and economically expensive. It has the problem of becoming a thing. Alternatively, in some stage movable support devices, smooth movement is achieved by air levitation, but there are problems in that the cost of the device itself increases and the number of accessory devices such as compressors increases.

The purpose of this invention is to solve the above problems, and it can be applied to support, guide, and drive stages of devices such as semiconductor manufacturing equipment and inspection equipment by using the magnetic levitation phenomenon of magnetic fluid. When a magnetic field is applied to a magnetic fluid, a spatial distribution of body force occurs in space, but this phenomenon has the same effect as creating a spatial density distribution of the fluid, and as a result, Focusing on the fact that it is possible to levitate a non-magnetic object with a density greater than that of the fluid, the non-magnetic object is constructed with the above stage, and the phenomenon described above is created at multiple locations on the stage, and the stage is suspended at three points. To provide a stage movable support device capable of precisely and reliably supporting and moving a stage by supporting it at multiple points such as four points.

[Means to solve the problem]

In order to achieve the above object, the present invention is configured as follows. That is, the present invention provides a stage made of a non-magnetic material and provided with a tapered edge, and a magnetic field held in each gap between iron cores located at a plurality of locations on the tapered edge of the stage. a stage support means having a fluid, the stage is movably floated and supported by applying a magnetic field to the iron core to apply a supporting force and a displacement force to the magnetic fluid; Regarding equipment.

Further, this stage movable support device has the iron core formed in a C-shape, and a permanent magnet inserted into a part of the iron core,
A steady magnetic field is applied to the gap portion of the iron core by the permanent magnet to hold the magnetic fluid.

Further, in this stage movable support device, an excitation coil is wound around the iron core, and the strength of the magnetic field applied to each of the gaps between the iron cores is adjusted by changing the magnitude of the current supplied to the excitation coil. The shape of the magnetic fluid is changed to adjust the movement of the stage.

The stage movable support device also includes a position sensor that detects the position of the stage, and controls the strength of the magnetic field applied to each of the gaps between the iron cores in response to a detection signal from the position sensor. and a controller that controls the position of the stage.

[Effect]

Since the stage movable support device according to the present invention is configured as described above, it operates as follows. That is, in this stage movable support device, multiple locations of the tapered edge of the stage made of a non-magnetic material are placed in the magnetic fluid held by a magnetic field in each gap between the iron cores, so that when a magnetic field is applied to the magnetic fluid, It produces the same effect as creating a spatial distribution of body force in space and a spatial density distribution of fluid, and as a result, it is possible to levitate a stage, which is a non-magnetic object, in the fluid with a density greater than that of the fluid. can. Since the stage itself has a Taber surface, the working force of the magnetic fluid is transmitted to the stage as a vector quantity. Therefore, under a predetermined magnetic field strength, the stage stands still at the position of the magnetic field minimum, and this position If you try to move the stage even slightly from
A restoring force acts to return the stage to its original position, and the stage is now supported by a three-dimensional spring in space, and the magnetic fluid forms a frictionless support device for the stage. Furthermore, by varying the strength of the magnetic field applied to each stage support means, the position of the stage supported by the stage support means can be moved.

〔Example〕

Embodiments of the stage movable support device according to the present invention will be described below with reference to the drawings. FIG. 1 is a perspective view showing one embodiment of the stage movable support device according to the present invention, FIG. 2 is an explanatory diagram for explaining the basic principle of configuring the stage movable support device of FIG. 1, and FIG. FIG. 2 is an explanatory diagram for explaining the displacement force of the stage movable support device of FIG. 1;

In FIG. 1, an embodiment of the stage movable support device according to the present invention is shown in which the stage is supported at two points on the A side and the B side. The stage 1 is a flat plate-shaped movable element made of a non-magnetic material such as acrylic resin, and has tapered surfaces 9, which are machined into an inclined surface of 10°, for example, at both edges thereof. .

Stage support means for movably supporting the stage 1 mainly includes an iron core 3, a magnetic fluid 2 disposed in the gap between the iron core 3, and an excitation coil 5 wound around the iron core 3.
It consists of The iron core 3 is formed into a C-shape so as to form a cavity. A permanent magnet 4 is inserted into the side of the iron core 3 opposite to the gap 7. Furthermore, a pair of iron cores 3.3 are arranged with spacers 6 facing each other, and the iron cores 3.3
A pair of excitation coils 5.5 are wound around the outer periphery of the coil. Further, a magnetic fluid 2 is placed in the gap formed between the iron cores 3. The stage 1 is arranged so that the gap portions of the plurality of pairs (two pairs in the figure) of the iron cores 3 are located at a plurality of locations (two locations on the A side and B side in the figure) on the edge with the tapered surface 9 of the stage 1. ing. The magnetic fluid 2 placed in the gap of the iron core 3 is moved by the permanent magnet 4 to the iron core 3.
It is maintained by applying a steady magnetic field to the air gap. It also has a function of applying a predetermined magnetic field, that is, a bias of a predetermined value, to the gap I between the iron cores 3 by the permanent magnet 4.

In this embodiment, a steady magnetic field for holding the magnetic fluid placed in the gap between the iron cores 3 is achieved by providing a permanent magnet 4; however, the present invention is limited to the permanent magnet 4. Alternatively, for example, a constant magnetic field can be applied to the gap by constantly passing a predetermined current through a pair of excitation coils 5, 5 wound around the outer periphery of the iron core 3. Or,
The magnetic fluid 2 can also be mechanically held in the gap between the iron cores 3.

The stage movable support device according to the present invention, having the above configuration, can movably float and support the stage 1 by applying a magnetic field to the iron core 3 and applying a supporting force to the magnetic fluid 2. As will be described later, when the stage 1 is supported at two points, the stage 1 is movable, for example, in the X direction or only in the X direction. Stage 1 is supported by 3 points,
If stage 1 is supported at 4 points or supported at multiple points depending on the size of stage 1, stage 1 will be
be able to move in the direction.

In this stage movable support device, the supporting force for supporting or floating the stage 1, that is, the floating blade, and the displacement force for displacing the stage 1 are provided as follows.

The stage 1 is given a supporting force by the magnetic fluid 2 by supplying current to the excitation coil 5 wound around the iron core 3 . In addition, by changing the magnitude of the current supplied to the excitation coil 5 wound around the iron core 3, the strength of the magnetic field given to each gap I between the iron cores 3 is adjusted by a command from a controller described later, and the magnetic fluid is By changing the shape of stage 2, the stage 1 can be adjusted to move in the X direction, the Y direction, or the XX direction.

The supporting force, or floating force, and displacement force acting on the stage movable support device will be explained with reference to FIGS. 2 and 3.

In FIG. 2, each excitation coil 5 is excited with respect to the iron core 3 of the stage support means on the A side and the iron core 3 of the stage support means on the B side, which are arranged at a predetermined interval in the X-axis direction. When a predetermined magnetic field is applied, the apparent specific gravity of the magnetic fluid 2 existing in the gap I5 between the iron cores 3 increases, and the buoyancy force F on the mover, that is, the stage increases. Since this buoyant force F acts perpendicularly to the tapered surface 9 of the tapered edge of the stage 1, the supporting force F2 that supports the stage 1 is given by the following equation.

F2=　F-co3θ This supporting force F2 is the gravity F applied to stage I.

When it grows larger, stage 1 becomes a "floating" state. When the stage 1 is floating, the stage cannot move in the X-axis direction due to the magnetic fluids 2 between the iron cores 3 in a spring-supported state, that is, in an elastically supported state, but in the Y-axis direction.
It is in a state where it can be displaced in the axial direction (perpendicular to the paper plane of FIG. 2, or see FIG. 1).

Next, A
When each exciting coil 5 is excited to apply the same magnetic field or different magnetic fields to the A side and B side to the iron core 3 of the stage support means on the side and the iron core 3 of the stage support means on the B side,
For stage 1, there are different buoyancy forces F on the A side and B side.
acts.

Therefore, the displacement force Fn acting on the stay 1 sill by the stage support means of A
direction (positive direction of the X-axis direction, second
In other words, FA= (FAI + FA2) S inθ
becomes. Similarly, the displacement force Fn acting on the stage I by the stage support means on the B side is in the negative direction of the X-axis direction, in which the stage 1 is to be removed from the magnetic fluid 2.
(leftward in Figure 2), that is, F++ = (
FBI+Fl+2) sinθ.

Here, when the respective displacement forces FA and F are equal, that is, when FA=FI], the stage 2 stands still in a balanced state with the center position. Also, F A> F
At time B, the stage 1 moves in the positive direction of the X-axis direction, that is, toward the B side (rightward in the figure). Furthermore, when FA<FR, the stage 1 moves from the negative direction portion of the X-axis direction to the A side (leftward in the figure). Therefore, if the strength of the current flowing through the excitation coil 5 in the stage support means is increased or decreased relative to the excitation coil 5 of each stage support means, the strength of the current can be increased or decreased in response to the strength of the current. The displacement force generated on each stage support means is different, so that the stage 1 itself undergoes a predetermined displacement or movement, and the position of the stage 1 is adjusted.

As shown in FIG. 3, A in the stage movable support device
An acrylic resin plate with a mass of 10 gr and a tapered surface 9 of 10° was used as stage 1, which constitutes the side stage support means and is a movable element, and the displacement force exerted on stage 1 by the stage support means was measured. . In this case, the measurement results of the displacement force Ft with respect to the distance l from the end of the tapered surface 9 of the stage 1 to the central axis of the iron core 3 while keeping the current applied to the excitation coil 5 constant are shown in FIG.

Furthermore, the results of measuring the individual response are shown in FIG. That is, in order to displace the stage 1, as an initial state, a current of 300 mA is applied to the excitation coil 5 of the stage support means on the A side in FIG. 1, and a current of 400 mA is applied to the excitation coil 5 of the stage support means on the B side in FIG. , the strength of the current is reversed.

FIG. 4 shows an embodiment in which the stage movable support device according to the present invention is supported at four points.

In this stage movable support device, the stage 10,
The stage 10 consists of a square flat plate made of non-magnetic material.
A tapered surface 9 is formed on the lower surface of each of the four outer peripheral edges. In addition, the iron core 3 of the stage support means with respect to the stage 10 is as shown by point 0, point E, point D, and point F.
They are arranged one after another at an angle of 90°. Even when the position of the stage 10 in the Y-axis direction is determined by the iron core 3 at point 0 and the iron core 3 at point D, the stage 10 is configured to be able to move freely against displacement in the X-axis direction. ,
In this case, the iron core 3 at point 0 and the iron core 3 at point D can serve as a guide for displacement in the X-axis direction. Conversely, even when the position of the stage 10 in the X-axis direction is determined by the iron core 3 at point E and the iron core 3 at point F, the stage 10 is configured to be freely movable with respect to displacement in the Y-axis direction. In this case, iron core 3 at point E and F
The dotted iron core 3 can serve as a guide for displacement in the Y-axis direction. Therefore, this stage movable support device is capable of supporting the stage 10 and controlling the drive of the moving portion of the stage 10 in the XX direction.

Next, adjustment of the movement of the stage 10 in this stage movable support device will be explained with reference to the embodiment shown in FIG. When adjusting the movement of the stage 10, a position sensor 11 for detecting the position of the stage 10 is provided at the bottom of the stage 10, for example.
For example, attach reflective mirrors in the X direction and the X direction,
It can be configured to measure the position of the stage 10 in the X direction and the X direction using light or laser. A position signal of the stage 10 detected by the position sensor 11 is input to the controller 15.

In response to the position signal of the stage 10 inputted to the controller 15, the controller 15 issues a command to move the stage 10 to a preset position, and supplies power to each excitation coil 55 in accordance with the command. control the strength of the current. By controlling the strength of the current supplied to each exciting coil 5, the strength of the magnetic field applied to the gap between each core 3 is controlled, and the strength of the magnetic field applied to the gap between each core 3 is controlled, and the strength of the magnetic field is applied to the gap between the cores 3 according to the strength of the magnetic field. The magnetic fluid 2 placed in acts on the stage 10, so that the stage 10
It is moved to a predetermined position by the action described above.

〔Effect of the invention〕

Since the stage movable support device according to the present invention is configured as described above, it has the following effects. That is,
This stage movable support device includes a stage made of a non-magnetic material and equipped with a tapered edge, and a stage that is held by a magnetic field in each gap between iron cores located at multiple locations on the tapered edge of the stage. and a stage support means having a magnetic fluid, and the stage is movably floated and supported by applying a magnetic field to the iron core and applying a supporting force and a displacement force to the magnetic fluid. The stage stands still at a position where the magnetic field is minimum, and if you try to move the stage even a little from this position, a restoring force acts and returns to the original position, and the stage is placed in a three-dimensional position in space. The magnetic fluid can provide a frictionless support device for the stage, and by varying the strength of the magnetic field in each stage support means,
It is also possible to move the position of the stage supported by the stage support means. That is, by effectively utilizing the magnetic levitation phenomenon of magnetic fluid, the stage itself can be moved and guided extremely smoothly and quickly.
Alternatively, it can be held precisely in place. Therefore, it can be applied extremely easily to X-Y axis stages that perform support, guidance, drive, etc. that require precision.
Therefore, it is preferable to apply it to facilities and devices such as semiconductor manufacturing equipment and inspection equipment, and the device itself is compact and the number of auxiliary equipment does not increase or increase, and the cost of the device itself can be reduced.

Further, the iron core is formed into a C-shape, a permanent magnet is inserted into a part of the iron core, and a steady magnetic field is applied to the gap part of the iron core by the permanent magnet to hold the magnetic fluid, so that the magnetic fluid is Even when the exciting coil is not excited, it is always maintained in the gap of the iron core, making it easy to handle and the device itself to be easily constructed. Further, the permanent magnet has a function of keeping a predetermined bias bias applied to the gap between the iron cores, and when the stage movable support device is operated, a magnetic force is applied to the excitation coil. It is also possible to reduce only the permanent magnet bone.

Furthermore, an excitation coil is wound around the iron core, and the magnitude of the current supplied to the excitation coil is changed to adjust the strength of the magnetic field applied to each of the gaps between the iron cores, thereby changing the shape of the magnetic fluid. a position sensor that detects the position of the stage; and a position sensor that controls the strength of the magnetic field applied to each gap between the iron cores in response to a detection signal from the position sensor. and a controller for controlling the position of the stage, it is possible to automatically control the posture of the stage itself, such as supporting, guiding, driving, etc., very quickly and accurately.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing one embodiment of the stage movable support device according to the present invention, FIG. 2 is an explanatory diagram for explaining the basic principle of the supporting force and displacement force of the stage movable support device of FIG. 3 is an explanatory diagram of a device for measuring the displacement force of the stage movable support device shown in FIG. 1, FIG. 4 is a perspective view showing another embodiment of the stage movable support device according to the present invention, and FIG. FIG. 6 is a diagram showing the displacement force characteristics of the support device, and FIG. 6 is a diagram showing the individual response of this stage movable support device. 1, 10-1---stage, 2-magnetic fluid, 3 iron core, 4----1 permanent magnet, 5-,,,-,,
- Excitation coil, 6 spacer, 9---Tapered surface, 11
-----Position sensor, 15=---Controller.

Claims (4)

[Claims] (1) A stage made of a non-magnetic material and having a tapered edge, and a magnetic fluid held by a magnetic field in each gap between iron cores located at multiple locations on the tapered edge of the stage. 1. A stage movable support device, comprising a stage support means, which movably floats and supports the stage by applying a magnetic field to the iron core and applying a supporting force and a displacement force to the magnetic fluid. (2) The iron core is formed into a C-shape, a permanent magnet is inserted into a part of the iron core, and the permanent magnet applies a steady magnetic field to the gap part of the iron core to hold the magnetic fluid. The stage movable support device according to claim 1. (3) An excitation coil is wound around the iron core, and the strength of the magnetic field applied to each gap between the iron cores is adjusted by changing the magnitude of the current supplied to the excitation coil, thereby changing the shape of the magnetic fluid. The stage movable support device according to claim 1, wherein the stage movable support device is configured to adjust the movement of the stage by changing the stage. (4) a position sensor that detects the position of the stage;
4. A controller that controls the position of the stage by controlling the strength of the magnetic field applied to each of the gaps between the iron cores in response to a detection signal from the position sensor. stage movable support device.