JP2997273B2 - Stage movable support device - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stage movable support device applicable to various devices such as a semiconductor manufacturing device, an inspection device, and a precision machine.

[Conventional technology]

In recent years, due to the development of VLSIs and the like, there has been an increasing demand for high-precision, high-speed, small-size and light-weight object positioning. In addition, as basic technologies of biotechnology, manipulators for cell micromanipulation, tables and supports for measuring instruments, etc.
In order to finely move a stage such as a moving table, a finely movable actuator is required. For these linear motions, linear actuators have attracted attention.

2. Description of the Related Art Conventionally, in a stage movable supporting device used in a semiconductor manufacturing apparatus, an inspection apparatus thereof, and the like, the stage is air-floated and a smooth movement is performed.

[Problems to be solved by the invention]

However, the linear actuator has a supporting controller, a guiding controller, or a driving controller for supporting, guiding, or driving a stage such as a moving table or a table, and the number of parts of the apparatus itself increases. However, there is a problem that it becomes complicated and economically expensive.

Alternatively, in the stage movable supporting device, smooth movement is performed by air levitation, but the cost of the device itself is increased, and there is a problem that the number of auxiliary devices such as compressors is increased.

SUMMARY OF THE INVENTION An object of the present invention is to solve the above-mentioned problem, and is applicable to supporting, guiding and driving a stage of an apparatus such as a semiconductor manufacturing apparatus and an inspection apparatus by utilizing a magnetic levitation phenomenon of a magnetic fluid. When a magnetic field is applied to a magnetic fluid, a spatial distribution of the body force is generated in the space. This phenomenon has the same effect as the spatial distribution of the fluid density, and as a result, Focusing on the fact that a non-magnetic object larger than the density of the fluid can be levitated, the non-magnetic object is composed of the above-mentioned stage, and the above-mentioned phenomenon is created at a plurality of points of the stage. An object of the present invention is to provide a stage movable support device that can support and move a stage precisely and reliably by supporting at a point.

[Means for solving the problem]

The present invention is configured as follows to achieve the above object. That is, the present invention provides a stage having a pointed edge formed of a non-magnetic material and having flat tapered surfaces on both surfaces opposed to a plurality of locations, and the taper of the edge at a plurality of locations of the stage. And a stage supporting means comprising a magnetic fluid disposed in each gap between the cores on which the edge of the stage is disposed, and a magnetic field applied to the cores. Thus, the force urged by the magnetic fluid is transmitted to the stage through the tapered surface of the edge as a vector amount of a supporting force and a displacement force. The present invention relates to a stage movable support device, which is movably levitated and supported by the displacement force.

In addition, the stage movable support device is configured such that the iron core is formed in a C-shape, a permanent magnet is inserted into a part of the iron core, and a steady magnetic field is applied by the permanent magnet to the gap of the iron core to transfer the magnetic fluid. It is what was held.

In addition, the stage movable supporting device winds an exciting coil around the iron core and changes the magnitude of the current supplied to the exciting coil to adjust the strength of the magnetic field applied to the gap between the iron cores. The stage is moved and adjusted by changing the shape of the magnetic fluid.

Further, the stage movable supporting device controls the strength of a magnetic field applied to the gap between the iron cores in response to a detection signal from the position sensor for detecting the position of the stage and the position sensor. And a controller for controlling the position of the stage.

[Action]

Since the stage movable support device according to the present invention is configured as described above, it operates as follows. In other words, this stage movable support device arranges a plurality of tapered edges of a stage made of a non-magnetic material in a magnetic fluid held by magnetic fields in gaps between iron cores. The same effect as when the spatial distribution of the body force is generated in the space and the density distribution of the fluid is generated spatially is given.
As a result, it is possible to levitate the stage, which is a non-magnetic object larger than the density of the fluid, in the fluid.

In particular, since the stage itself has a tapered surface, the working force of the magnetic fluid is transmitted to the stage as a vector, so that the stage stops at the position of the minimum magnetic field under a predetermined magnetic field strength, If you try to move the stage from this position even a little, the restoring force works and it returns to the original position, the stage is just supported by the three-dimensional spring in space, and the magnetic fluid frictionally A support device without the support. Further, the position of the stage supported by the stage supporting means can be moved by variously changing the strength of the magnetic field in each stage supporting means.

〔Example〕

Hereinafter, an embodiment of a stage movable support device according to the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing an embodiment of a stage movable support device according to the present invention, FIG. 2 is an explanatory diagram for explaining the basic principle of the stage movable support device shown in FIG. 1, and FIG. FIG. 3 is an explanatory diagram for explaining a displacement force of the stage movable support device of FIG. 1.

FIG. 1 shows an embodiment of the stage movable support device according to the present invention in a state where it is supported at two points on an A side and a B side. The stage 1 is a plate-like movable element made of a non-magnetic material such as an acrylic resin, and a tapered surface 9 formed into a flat inclined surface of, for example, 10 ° is formed at edges of both ends thereof. ing.

The stage supporting means for movably supporting the stage 1 is mainly composed of an iron core 3, a magnetic fluid 2 disposed in a gap L of the iron core 3, and an exciting coil 5 wound around the iron core 3. The iron core 3 is formed so that the gap L is formed.
It is formed in a character shape. A permanent magnet 4 is inserted into the iron core 3 on the side facing the gap L. Furthermore, a pair of iron cores 3,
A pair of exciting coils 5 are wound around the outer periphery of the iron core 3.

The magnetic fluid 2 is disposed in a gap L formed between the iron cores 3. At a plurality of locations (two locations on the A side and the B side in the figure) of the edge portion having the tapered surface 9 of the stage 1, a plurality of pairs (two pairs in the figure) of the gaps L of the iron core 3 are located. Are located. Void L of iron core 3
The magnetic fluid 2 arranged in the iron core 3 is
Is maintained by applying a steady magnetic field to the gap L. Further, it also has a function of applying a predetermined magnetic field, that is, a bias of a predetermined value to the gap L between the iron cores 3 by the permanent magnet 4.

In this embodiment, the steady magnetic field for holding the magnetic fluid disposed in the gap L between the iron cores 3 is achieved by providing the permanent magnets 4. However, the present invention is not limited to the permanent magnets 4. Alternatively, a predetermined magnetic field can be constantly applied to the pair of exciting coils 5, 5 wound around the outer periphery of the iron core 3 to apply a steady magnetic field to the gap L. Alternatively, the magnetic fluid 2 can be mechanically held in the gap L between the iron cores 3.

The stage movable supporting device according to the present invention can movably levitate and support the stage 1 by applying a magnetic field to the iron core 3 to apply a supporting force to the magnetic fluid 2 in the above configuration. As described later, stage 1 is 2
When the stage is supported, the stage 1 can move only in the X direction or the Y direction, for example. Stage 1 supports 3 points, 4
When the point support or the multi-point support at a large number of parts according to the size of the stage 1 is performed, the stage 1 can move in the XY directions.

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

The stage 1 is provided with a supporting force by the magnetic fluid 2 by supplying a current to the exciting coil 5 wound around the iron core 3. The exciting coil 5 wound around the iron core 3
The magnitude of the magnetic field applied to each gap L between the iron cores 3 is changed by changing the magnitude of the current supplied to the iron core 3 in accordance with a command from a controller to be described later to change the shape of the magnetic fluid 2, thereby changing the shape of the stage 1. Can be moved and adjusted in the X, Y or XY directions.

The supporting force, ie, the floating force, and the displacement force acting on the stage movable support device will be described with reference to FIGS.

In FIG. 2, each exciting coil 5 is excited with respect to the core 3 of the stage supporting means on the side A and the core 3 of the stage supporting means on the side B 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 L between the iron cores 3 increases, and the buoyancy F to the mover, that is, the stage 1 increases. Buoyancy F Since the acting perpendicular to the flat tapered surface 9 of the tapered edge of the stage 1, when a taper angle relative to the plane of the tapered surface 9, theta, supporting force F ₂ which supports the stage 1, the following formula Given by

F ₂ = F · cos θ When the supporting force f ₂ becomes larger than the gravitational force f ₀ applied to the stage 1, the stage 1 is in a floating state. When the stage 1 is lifted, the stage 1
The magnetic fluid 2 between them cannot move in the X-axis direction in a spring supported state, that is, in an elastically supported state, but can be displaced in the Y-axis direction (perpendicular to the plane of FIG. 2 or see FIG. 1). It is in a state.

Next, A which is arranged at a predetermined interval in the X-axis direction
When the same magnetic field or a different magnetic field is applied to the A side and the B side by exciting each exciting coil 5 to the iron core 3 of the stage supporting means on the side and the core 3 of the stage supporting means on the B side, For 1, a different buoyancy F acts on the A side and the B side. Therefore, the displacement force FA acting on the stage 1 by the stage supporting means on the side _A is determined in the direction in which the stage 1 is to be removed from the magnetic fluid 2 (positive direction in the X-axis direction,
It works to the right in FIG. 2 and upward in FIG. 3, that is, F _A = (F _A1 + F _A2 ) sin θ. Similarly, displacement force F _B acting on the stage 1 by the B-side of the stage support means, the direction in which the stage 1 is about to be removed from the magnetic fluid 2 (negative direction of the X-axis direction, in the second drawing to the left) to work, that is, the _{F B = (F B1 + F} B2) sinθ.

Here, when each of the displacement force F _A and F _B are equal, ie, F
The case of _A = F _B, Stage 1 is still in a state commensurate placed in the center.

When F _A > F _B , the stage 1 moves in the positive direction of the X-axis, that is, in the side B (to the right in the drawing).

Further, when the F _A <F _B, stage 1 moves in the negative direction, i.e., A-side of the X-axis direction (the left direction in the drawing).

Therefore, if the intensity of the current flowing through the exciting coil 5 of the stage supporting means is increased or decreased with respect to the exciting coil 5 of each stage supporting means, each stage responds to the intensity of the current. The displacement force generated in the support means is different, so that the stage 1 itself performs a predetermined displacement or movement, and the position of the stage 1 is adjusted.

As shown in FIG. 3, the stage supporting means on the A side in the stage movable supporting device is constituted, and the mass of the stage 1 which is a movable element is 10 gr, and the taper angle θ of the flat tapered surface 9 of the stage 1 is 10 °. Using the acrylic resin plate formed in ゜, the displacement force applied to the stage 1 by the stage supporting means was measured.

In this case, the current applied to the exciting coil 5 constant, the measurement results of the displacement force F _A against the distance l from the end of the tapered surface 9 of the stage 1 to the center axis of the core 3, shown in Figure 5.

FIG. 6 shows the result of measuring the initial response. That is, in order to displace the stage 1, as an initial state, 300 mA is applied to the exciting coil 5 of the stage supporting means on the side A in FIG.
A current of 00 mA was passed, and then the current was reversed and passed.

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 is made of a square flat plate made of a non-magnetic material, and tapered surfaces 9 are formed on the upper and lower surfaces at four outer peripheral edges of the stage 10.

In addition, the iron core 3 of the stage supporting means
Are sequentially arranged at an angle of 90 ° as shown by points C, E, D and F. Stage 10 is iron core 3 at point C
The stage 10 is configured to be freely movable with respect to the displacement in the X-axis direction even when the position in the Y-axis direction is determined by the The iron core 3 and the iron core 3 at the point D can function 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 the point E and the iron core 3 at the point F, the stage 10 can freely move with respect to the displacement in the Y-axis direction. In this case, the core 3 at the point E and the core 3 at the point F can function as a guide for displacement in the Y-axis direction.

Therefore, the stage movable support device can support the stage 10 and control the movement, that is, the drive of the stage 10 in the XY directions.

Next, the movement adjustment of the stage 10 in the stage movable support device will be described 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, for example, below the stage 10. For example, the position sensor 11 can be configured such that reflection mirrors are attached in the X direction and the Y direction, and the position of the stage 10 in the X direction and the Y direction is measured using light or laser. The 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 input to the controller 15, the controller 15 issues a command to move the stage 10 to a predetermined position, which is supplied to each excitation coil 5 in accordance with the command. Control the current intensity. By controlling the strength of the current supplied to each excitation coil 5, the strength of the magnetic field applied to the gap L between the iron cores 3 is controlled, and the gap L is adjusted according to the strength of the magnetic field. The magnetic fluid 2 disposed on the stage 10 acts on the stage 10, and the stage 10 is moved to a predetermined position by the above-described operation.

〔The invention's effect〕

Since the stage movable support device according to the present invention is configured as described above, the stage is stopped at a position where the magnetic field is minimum under a predetermined magnetic field strength, and the stage is moved from this position as much as possible. Then, the restoring force acts and returns to the original position, the stage is just supported in space by a three-dimensional spring, and the magnetic fluid can provide a support device without friction to the stage, The position of the stage supported by the stage supporting means can be moved by variously changing the strength of the magnetic field in each of the stage supporting means.

That is, this stage movable support device can move and guide the stage itself extremely smoothly and quickly by effectively utilizing the magnetic levitation phenomenon of the magnetic fluid.
Alternatively, it can be accurately held at a predetermined position.

Therefore, this stage movable support device can be very easily applied to an XY axis stage that performs support, guidance, drive, or the like that requires precision, and therefore, equipment such as semiconductor manufacturing equipment, inspection equipment, etc. It is preferable to be applied to an apparatus, and furthermore, the apparatus itself is compact, and there is no increase or increase in incidental facilities, so that the cost of the apparatus itself can be reduced.

In addition, the stage movable support device forms the iron core in a C-shape, inserts a permanent magnet into a part of the iron core, and holds the magnetic fluid by applying a steady magnetic field to a gap of the iron core by the permanent magnet. Therefore, the magnetic fluid is always maintained in the gap of the iron core even when the excitation coil is not excited, so that the handling is easy and the device itself can be simply configured. Further, the permanent magnet has a function of keeping a predetermined value of a bias applied to the gap between the iron cores. When the stage movable support device is operated, a magnetic force applied to the exciting coil is provided. Can be reduced by the amount of the permanent magnet.

Further, the stage movable supporting device is configured such that an exciting coil is wound around the iron core, and the magnitude of the current supplied to the exciting coil is changed to adjust the strength of the magnetic field applied to each of the gaps between the iron cores. The stage adjusts the position of the stage by changing the shape of the magnetic fluid. The position sensor detects the position of the stage, and is applied to each of the gaps between the iron cores in response to a detection signal from the position sensor. And a controller for controlling the position of the stage by controlling the intensity of the applied magnetic field, so that the attitude control such as support, guidance, and drive of the stage itself can be controlled very quickly and accurately automatically. it can.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an embodiment of a 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 view for measuring the displacement force of the stage movable supporting device of FIG. 1, FIG. 4 is a perspective view showing another embodiment of the stage movable supporting device according to the present invention, and FIG. FIG. 6 is a diagram showing a displacement force characteristic of the supporting device, and FIG. 6 is a diagram showing an individual response of the stage movable supporting device. 1,10 ... stage, 2 ... magnetic fluid, 3 ... iron core, 4 ... permanent magnet, 5 ... excitation coil, 6 ... spacer, 9 ... taper surface, 1
1 …… Position sensor, 15 …… Controller.

──────────────────────────────────────────────────続 き Continued on the front page (58) Fields investigated (Int. Cl. ⁷ , DB name) B23Q 1/00-1/76 G12B 5/00 H01L 21/68 H02K 44/00

Claims (4)

(57) [Claims] A stage having a pointed edge made of a non-magnetic material and having flat tapered surfaces on both sides facing a plurality of locations; and the tapered surfaces of the edges at a plurality of locations on the stage. And a stage supporting means comprising a magnetic fluid disposed in each gap between the cores on which the edge of the stage is disposed, and a magnetic field applied to the cores. Transmitting the force urged by the magnetic fluid to the stage through the tapered surface of the edge as a vector amount of a supporting force and a displacement force,
A stage movable supporting device, wherein the stage is movably levitated and supported by the supporting force and the displacement force urged by the magnetic fluid. 2. The method according to claim 1, wherein the iron core is formed in a C-shape, a permanent magnet is inserted into a part of the iron core, and the magnetic fluid is held by applying a steady magnetic field to the gap of the iron core by the permanent magnet. The stage movable support device according to claim 1, wherein: 3. An exciting coil is wound around the iron core, and the magnitude of a current supplied to the exciting coil is changed to adjust the strength of a magnetic field applied to each of the gaps between the iron cores to adjust the strength of the magnetic fluid. The stage movable support device according to claim 1, wherein the stage is moved and adjusted by changing its shape. 4. A position sensor for detecting the position of the stage, and controlling the strength of a magnetic field applied to the gap between the iron cores in response to a detection signal from the position sensor to determine the position of the stage. The stage movable support device according to claim 3, further comprising a controller that controls the stage.