JP2547403B2 - Magnetic levitation transport device for vacuum equipment - Google Patents

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a magnetic levitation transfer apparatus for a vacuum apparatus, and more particularly to a magnetic levitation transfer apparatus for a vacuum apparatus used to transfer a semiconductor wafer or the like in a vacuum process apparatus.

2. Description of the Related Art Conventionally, there is a magnetic levitation system as a mechanism capable of moving in parallel in the atmosphere without sliding and without contact, and usually a levitation body is equipped with a position sensor, an electromagnet, a power supply, and the like.

Separately, as a device that can move in parallel in a vacuum for a long distance without sliding and contacting without generating dust, a transfer table that is guided along a transfer path defined in the vacuum container is floated. A levitation body member that supports the levitation body member, and permanent magnets are attached to both sides of the levitation body member, and the levitation body member cooperates with each of the permanent magnets to balance the levitation body member over the entire conveyance path of the conveyance table without contact. The levitation electromagnet guided by the above is provided outside the wall of the vacuum device, and a mover made of a magnetic material having a plurality of teeth equidistantly parallel to each other is provided on the levitation member and faces the mover. Then positioned,
A stator having a large number of windings that are sequentially excited to drive the mover outside the vacuum device wall is provided on the vacuum device wall along the movement path of the levitation member. A magnetic levitation transfer device for a vacuum device is known.

Due to the trend toward higher integration of semiconductor devices these days, contamination of the substrate due to dust must be kept as low as possible not only during the processing of the substrate but also during the transfer from one processing step to the next processing step. Releasing the vacuum when transferring the substrate from one processing step to the next is not only not only a problem of dust, but also not preferable from the viewpoint of the time and energy consumption of the entire process, and these problems are solved. As one means for achieving this, there has been proposed the magnetic levitation transfer device for a vacuum device as described above, which can move in parallel in a vacuum for a long distance in a non-sliding and non-contact manner without generating dust.

Problems to be Solved by the Invention In such a conventionally known device, there is no problem of dust due to contact or sliding, and although the electromagnet, the power source, etc. are arranged outside the vacuum container, the permanent magnet is in vacuum. Since it is provided in the above, a serious problem arises that the gas emitted from the permanent magnet is generated. The gas generated from such a permanent magnet will adversely affect the object to be processed.
Corrosion of the permanent magnet also poses a problem depending on the type of gas introduced into the vacuum container.

Further, such a conventional device cannot be used when a force is applied in the movement axis direction because the force of the permanent magnet for levitation is not effectively used as a holding force in the movement axis direction. For example, during vertical transportation, it was difficult to stop and move against the gravity of the floating body and the transported object.

In addition to the permanent magnet for levitating and the electromagnet for position control, it is necessary to separately provide a mover and a stator for movement, which makes the structure complicated and the manufacturing and maintenance costs are high. It was a thing.

Further, of the two directions orthogonal to the movement axis direction, active position control is performed in one direction, but active control is not performed in the other one direction, so positioning with high accuracy is performed. Was difficult.

In addition, the conventional device, over the entire moving path of the floating body,
Since the electromagnets for controlling the flying position are installed, a large amount of electromagnets was needed when the passage was long.

Therefore, an object of the present invention is to provide a magnetic levitation transfer device for a vacuum device which can solve the above-mentioned various problems in the conventional magnetic levitation transfer system.

Means for Solving the Problems To achieve the above object, a magnetic levitation transfer device for a vacuum device according to the present invention floats and supports a transfer table guided along a transfer passage defined in a vacuum container. It has a T-shaped or cruciform floating body, a guide arranged outside the vacuum container and moving along the transfer passage, and means for driving the guide, and is orthogonal to the moving direction of the floating body. Magnetic members are attached to both side ends, and the guider is formed in a U shape so as to face each magnetic member through the wall of the vacuum container and to sandwich each magnetic member. A magnetic yoke is attached, and a levitation permanent magnet that guides the levitation body in a non-contact and non-sliding state in a balanced state over the entire conveyance path, and a position control electromagnet are attached to the yoke. In addition, each of the guides has a floating body. A feature is that a plurality of position sensors for detecting a horizontal flying position and a vertical flying position are attached.

In the magnetic levitation transport device for vacuum device according to the present invention configured as described above, the levitation body arranged in the vacuum container is
By the interaction between the magnetic member attached to itself and the levitation permanent magnet provided outside the vacuum vessel, the equilibrium state is maintained along the transfer passage in the vacuum vessel without sliding and contacting. Can be moved. In this case, since the position control electromagnet is also arranged outside the vacuum container together with the levitation permanent magnet, the gas discharged from these magnet members does not affect the vacuum side. In addition, the attraction force between the magnetic material member of the levitation body and the levitation permanent magnet of the guide is modulated by the position control electromagnet according to the output of the position sensor to control levitation, so a combination of the magnetic material and electromagnet is used. The power consumption of the electromagnet is reduced in proportion to the levitated object.

Further, the levitation body has a holding force in the movement axis direction, and a permanent magnet attached to the guide so that the N pole and the S pole guided to the yoke are alternately positioned along the movement axis direction of the levitation body. , Is strong because it is provided by the attractive force between the magnetic member mounted on the floating body. Therefore, it can be used even when a force acts in the moving axis direction, and can be applied as, for example, a vertical conveying device.

Furthermore, by controlling the movement of the guide using a driving means provided outside the vacuum container, the moving speed of the floating body,
It is possible to arbitrarily control the moving distance and the stop position.

In addition, since the floating body performs active position control by the electromagnet and the position detection sensor in two directions orthogonal to the moving axis direction, extremely accurate positioning can be performed.

Embodiment An embodiment of the present invention will be described below with reference to the accompanying drawings.

FIG. 1 shows a magnetic levitation transfer device for a vacuum device according to an embodiment of the invention, in which a vacuum container 1 made of a non-magnetic material is installed along a transfer path. The vacuum container 1 has a substantially T shape, and a hollow transfer passage is defined by the upper wall 2 and the lower wall 3, and the upper wall 2 is hermetically attached to the lower wall 3 via a gasket 4.

A levitation body 5 having a T-shape is arranged in the vacuum vessel 1, and the levitation body 5 is guided along a transfer passage formed in the vacuum vessel. A carrier 6 is attached to the floating body 5 in the direction of its moving axis. A gripping member 7 for gripping the semiconductor wafer 9 and the like is formed at the tip of the carrier. The magnetic member 8 is attached to each end of the levitation body 5, that is, a side portion orthogonal to the moving axis direction thereof.

A permanent magnet 10 is arranged so as to face each of these magnetic members 8 via the walls 2 and 3 of the vacuum container, and the permanent magnet makes the levitating body 5 contactless and non-sliding over the entire conveying passage. Guide in a state of dynamic equilibrium.

The permanent magnets 10 are fixed to the yoke 11 of a magnetic body formed in a U-shape so as to sandwich each magnetic body member 8, and the N pole and the S pole guided by the yoke are arranged in the moving axis direction of the levitation body. It is arranged so that it may be located alternately along. Coils 11a, 11b and 11c are attached to the respective yokes to form an electromagnet 12 together with the yokes.

The levitation body 5 provided in the vacuum vessel floats due to the magnetic force between the magnetic member 8 attached to the levitation body 5 and the permanent magnet 10 arranged outside the vacuum vessel, and the equilibrium state is maintained. It is possible to move along the transfer passage in the vacuum container in a sliding / non-contact state.

A linear shaft 13 is arranged outside the vacuum container 1 along the transfer passage, and guides 14, 15 are provided on the linear shaft 13.
Moves along the transfer passage outside the vacuum container. A ball screw 16 arranged parallel to the linear shaft 13 is attached to the guider, which is driven by a stepping motor (not shown). Therefore, the guide is a ball screw driven by a stepping motor.
The 16 makes it possible to move and stop at any position at any speed.

A permanent magnet 10, an electromagnet 12, and a position detection sensor 17 for detecting a floating position are mounted on the guides 14 and 15.

The position sensor 17 is orthogonal to the moving axis direction of the levitation body 2
Direction of the coil 11a, 11b, 11c of the electromagnet 12
Control the excitation current to the.

The exciting current of the electromagnet 12 is controlled by the detection signal of the position sensor 17, and the position of the electromagnet 12 is actively controlled in two directions orthogonal to the moving axis direction of the levitation body 5.

As shown in FIG. 2, the magnetic member 8 mounted on the levitation body in the vacuum container, the permanent magnet 10 and the yoke 11 arranged outside the vacuum container through the vacuum wall 3, and the solid line arrow in the figure Such a magnetic circuit is formed and an attractive force is generated. The suction force thus generated serves as the levitation force of the levitation body 5 and the holding force in the movement axis direction. When the displacement occurs in the direction shown by the solid arrow F in the figure, the output signal of the position sensor 17 mounted on the guides 14, 15 changes, and the amount of current supplied to the electromagnet 12 is the broken line shown in the figure. It is controlled in the direction of increasing the magnetic flux in the direction of the arrow. As a result, a force is applied in the direction of the solid arrow f to cancel the above-mentioned displacement.

In the operation of the apparatus according to the present invention configured as described above, the levitation body 5 slides together with the carrier table 6 by the mutual attraction action between the magnetic member mounted on the levitation body 5 and the levitation permanent magnet 10. It floats in a vacuum container without any movement or contact.

The guides 14 and 15 are attached to the permanent magnets 10 and electromagnets 1.
The ball screw 16 driven by a stepping motor together with the position sensor 17 and the position sensor 17 can be moved to a predetermined position along the conveying path.

The levitation body 5 can be moved along the conveying path by being driven by the guide while maintaining the equilibrium state by the electromagnet 12 whose exciting current is controlled by the signal of the position sensor 17.

This type of position control can be performed at each tip of the T-shaped floating body.
The floating body 5 can be positioned extremely accurately because the floating body 5 is positioned at a total of 6 positions.

In this embodiment, the carrier 6 has a shape that is long in the direction of the moving axis, but it may have any shape regardless of the shape shown.

The levitation body 5 has been described as a T-shape in this embodiment, but it may have any shape as long as it can perform active position control in two directions orthogonal to the movement axis direction, and thus may be, for example, a cross shape. .

The guide element is driven by a ball screw driven by a stepping motor, but another method, for example, a driving means by a linear stepping motor can be used.

Effects of the Invention As described above, in the magnetic levitation transfer device for a vacuum device according to the present invention, the transfer table is attached to the levitation body that is guided along the transfer passage defined in the vacuum container,
By attaching a magnetic member to each end of the levitation body,
A non-contact balanced state of the carrier table and the object to be carried by the carrier table due to mutual attraction between the magnetic members and a permanent magnet arranged outside the vacuum container. You can get directions at. Therefore, generation of dust due to sliding is suppressed, and the life of the device is extended.

Since the holding force of the floating body in the axial direction of movement is strong, it can be used even when a force acts in the axial direction, and vertical transportation is possible. Therefore, the transport system can be configured in any orientation and posture.

Further, since the levitation permanent magnet, the electromagnet for controlling the levitation position, and the driving means are all arranged outside the vacuum container, the inside of the vacuum container may be contaminated by the released gas and dust generated from these elements. There is no It is also possible to prevent these elements from being corroded by the gas introduced into the vacuum container.

Moreover, since the position control of the floating body is performed by the electromagnet and the position detection sensor in two directions orthogonal to the moving axis direction of the transfer passage, the floating body and the transfer base must be moved / stopped at the correct positions. You can

Further, since it is not necessary to provide an electromagnet for controlling the floating position over the entire length of the transfer passage, it can be easily applied to a long-distance transfer and the manufacturing cost can be greatly reduced.

[Brief description of drawings]

FIG. 1 is a perspective view showing a magnetic levitation transfer device for a vacuum device according to an embodiment of the present invention, and FIG. 2 is a schematic diagram showing a magnetic circuit of this device. In the figure, 1: vacuum vessel, 2: vacuum vessel upper wall, 3: vacuum vessel lower wall,
5: Floating body, 6: Carrier, 8: Magnetic member, 10: Permanent magnet, 11:
Yoke, 11a to 11c: Coil, 12: Electromagnet, 14, 15: Guide,
16: Ball screw, 17: Position detection sensor

Claims (4)

(57) [Claims] 1. A T-shaped or cruciform levitation body for supporting a carrier platform, which is guided along a transfer passage defined in a vacuum container, and a transfer member disposed outside the vacuum container along the transfer passage. And a means for driving the guide, and magnetic members are attached to both side ends of the floating body orthogonal to the moving direction of the floating body. On the other hand, a yoke made of a magnetic material, which is formed in a U shape so as to sandwich each magnetic material member so as to face each other through the wall of the vacuum container, is attached to the yoke, and the floating body is not provided over the entire conveying passage. A permanent magnet for levitation that guides levitation in a contact / non-sliding equilibrium state and an electromagnet for position control are mounted, and the guider detects the horizontal levitation position and vertical levitation position of the levitation body, respectively. Is equipped with multiple position sensors Magnetic levitation transportation device for a vacuum apparatus. 2. A U-shaped magnetic material yoke comprising two or more yokes, the permanent magnet being fixed between adjacent yokes,
The device according to claim 1, wherein the N poles and the S poles guided to the respective yokes are alternately positioned along the moving axis direction of the levitation body. 3. The apparatus according to claim 1, wherein the means for driving the guide element comprises a ball screw and a stepping motor for driving the ball screw. 4. An apparatus according to claim 1 or 2, wherein the means for driving the guide comprises a linear stepping motor.