JPH0812077A - Magnetic levitation conveying device for vacuum device - Google Patents

Abstract

PURPOSE:To make not only straight motions but also a rotational motion in the magnetically levitated condition and provide possibility of service in an ultrahigh vacuum atmosphere by partitioning a guide of a conveying device by a vacuum bulkhead into a robot chamber and a conveying chamber, and furnishing a magnetic levitating means both on a robot hand and a moving element. CONSTITUTION:When a robot 7 hand 13 furnished with a magnetic levitating means is put in straight motions within a robot chamber 8, a moving element 9 furnished with magnetic levitating means in a conveying chamber 10 partitioned by a vacuum bulkhead 6 complies with these robot hand motions, is levitated magnetically, and makes also straight motions. When the hand 13 makes a rotational motion, the moving element 9 also makes rotational motion while levitated magnetically and can be moved to a work conveying position contactlessly by turning the hand 13. Because the internal space 5 of the conveying device 1 is partitioned by the vacuum bulkhead 6 into the robot chamber 8 and conveying chamber 10, only the element 9 exists in the internal space even through the conveying chamber 10 is put in an ultrahigh vacuum atmosphere, and there is no risk of impairing the atmosphere with ultrahigh vacuum.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention performs a linear operation and a rotary operation applied to the transfer of substrates and other workpieces in a chamber of a vacuum processing apparatus such as a sputtering apparatus or an etching apparatus used in a semiconductor manufacturing process. The present invention relates to a magnetic levitation transport device for vacuum devices.

[0002]

2. Description of the Related Art Conventionally, for example, in a semiconductor manufacturing process,
When a silicon wafer workpiece is repeatedly sputtered or etched, the workpiece is transported to several sputtering chambers or etching chambers by a single transport device. Normally, an articulated robot is used as a transfer device, and a work to be processed is sent to a sputtering chamber or the like arranged around the transfer device via a gate valve, and the processed work is transferred to the next chamber.

Further, as a transfer device, a magnetic levitation transfer device is used as a magnetic levitation transfer device to move a magnetic levitation mover in a non-contact manner, thereby linearly transferring a work.

[0004]

When the articulated robot is used as described above, since the robot hand can perform linear operation and rotational operation (R-θ operation), the work can be relatively freely moved to a desired place. However, in order to reduce the radius of gyration of the arm and to give flexibility to the operation, the arm is folded using a bearing or the like at the joint between the links. For example, an arm of an articulated robot is divided into a first arm, a second arm, and a hand part that holds a work, the parts are connected to each other by a link, and a bearing is provided at a joint part between the link parts to form an angle between the parts. Although it is possible to freely change, the bearing causes wear due to sliding and dust due to this, so
There is a disadvantage that a clean environment cannot be maintained. Further, recently, it is required to make the background pressure of the film forming chamber an ultrahigh vacuum for the purpose of improving the film forming quality. For that purpose, it is necessary to place the transfer device in an ultrahigh vacuum atmosphere. However, in an articulated robot, a large amount of gas is released due to the complexity of the structure of the operating portion, and pressure fluctuation occurs due to operation, which is not suitable for use in ultra-high vacuum. Since the magnetic levitation transfer device has no sliding part, it does not have a problem of dust generation, but the operation of the magnetic levitation mover is limited to a simple one such as a linear operation, and the linear operation and the rotary operation are simultaneously performed.
The -θ type operation cannot be performed and cannot be used as a transfer device of a vacuum device having many chambers.

It is an object of the present invention to provide a magnetic levitation transfer device for a vacuum device which can perform not only linear operation but also rotational operation in a magnetically levitated state and is suitable for use in an ultrahigh vacuum atmosphere. .

[0006]

According to the present invention, the chamber of the transfer device is divided into an airtight robot chamber containing a driving robot and a transfer chamber containing a moving element for transferring a work through a vacuum partition. The above-mentioned object is achieved by providing a magnetic levitation device that separates the robot and each of the mover to move the mover magnetically. For the above-mentioned purpose, a holding device such as an electrostatic chuck for holding the work is provided at the tip of the moving element formed in the longitudinal direction, and the magnetic levitation means is provided in the middle part of the moving element for levitation. Body and a levitation control electromagnet provided on the hand facing the levitation magnetic body to magnetically levitate the mover in a cantilevered state, and to supply power to the holding device to the hand And a secondary transformer separated from the primary transformer and a secondary transformer housed in the case in the mover.
This can be achieved more appropriately by installing the secondary transformer at a position where the movement of the center of gravity of the moving element when holding the work of the holding device is within the range of the magnetic levitation means. The robot chamber is controlled to a pressure higher than that of the transfer chamber, the differential pressure between the two chambers is controlled to be a certain value or less, and further, a plurality of the magnetic levitation devices are provided symmetrically on the left and right of the mover. It is also possible to configure the magnetic material for use with a floating control electromagnet provided at a position corresponding to each magnetic material for floating of the hand.

[0007]

When the hand provided with the magnetic levitation means of the robot moves linearly in the robot chamber, the mover attached with the magnetic levitation means in the transfer chamber, which follows the movement of the robot, magnetically levitates and linearly moves, When the hand makes a rotational movement, the mover also rotates while being magnetically levitated, and the hand can be operated to move the mover to a required work transfer position without contact. Since the chamber of the transfer device is divided into an airtight robot chamber containing a robot and a transfer chamber containing a moving element through a vacuum partition, even if the transfer chamber has an ultrahigh vacuum atmosphere, Since only the moving element is disposed in the robot, the robot having a complicated structure and a large surface area and a large amount of gas is isolated, so that the atmosphere of the ultra-high vacuum is not damaged. Further, the robot chamber is airtight, and by evacuating the chamber to a pressure of several hundred Pa, which is higher than the pressure in the transfer chamber, it is possible to prevent the vacuum partition wall from bending so as not to interfere with the operation of the robot. Normal lubrication oil can be used to lubricate the sliding parts of the robot in a moderate vacuum, so maintenance is cheaper, and even if bearings are used in the sliding parts to improve durability, dust and released gas will remain in the transfer chamber. It is possible to maintain a clean atmosphere in the space connected to the transfer chamber without invading. Therefore, a robot having a complicated structure with multiple joints such as a folding mechanism and a multi-stage ladder mechanism can be used, and the hand can be operated with a small radius of rotation and the robot can be made small.

Further, the mover is magnetically levitated in a cantilevered state by a magnetic body such as a levitation permanent magnet provided on the mover and a levitation control electromagnet provided on the hand. When the holding device such as the electrostatic chuck holds the work, the center of gravity of the moving element is moved. However, the center of gravity of the moving element is always present within the existence region of the levitation magnetic body. For this purpose, a secondary transformer of a separation type transformer that feeds power to the holding device is provided in the moving element, and the secondary transformer functions as a counterweight to limit the range of movement of the center of gravity to determine whether or not there is a workpiece. The change in weight can prevent the front and rear of the moving element from being out of balance. By providing the secondary transformer with such a function, it is possible to prevent the weight of the entire moving element from increasing. The levitation distance, pitching, rolling, guiding direction, and yawing of the mover are controlled by a levitation magnetic body provided with a plurality of magnetic levitation means symmetrically on the left and right of the mover and each levitation magnetic body of the hand. The levitation control electromagnets are provided at positions corresponding to the body, and the current of the levitation control electromagnet can be controlled.

[0009]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A preferred embodiment of the present invention will be described with reference to the attached drawings. FIG. 1 shows an outline of a transfer device of the present invention, which is a vacuum device for manufacturing a semiconductor by subjecting a work a of a silicon wafer to film formation and etching. An example of application is shown. Necessary vacuum devices such as a sputtering chamber 2, an etching chamber 3, a loading chamber, and an unloading chamber are arranged around the transfer device 1, and the interior of these vacuum devices is provided by an appropriate exhaust means. The work a is evacuated to an ultrahigh vacuum, and the work a is subjected to film formation and etching. The carrier 1 sequentially puts the work a in and out of these chambers in accordance with the manufacturing process, and semiconductor circuits and the like are formed in the work a.

As shown in FIG. 2, the transfer device 1 is airtightly covered with a cover 4, and a room 5 surrounded by the cover is provided.
By a vacuum partition 6 made of metal such as aluminum alloy.
The chamber is divided into chambers, and the upper chamber is a robot chamber 8 accommodating the driving multi-joint robot 7, and the lower chamber is a transport chamber 10 accommodating a mover 9 for transporting the work. An ultra-high vacuum pump 11 is connected to the transfer chamber 10 so that an ultra-high vacuum atmosphere matching the pressure of the surrounding sputtering chamber 2 can be obtained inside the transfer chamber 10, and sputtering is performed around the transfer chamber 10. A required number of passages 41 having a gate valve 40 communicating with the inside of the vacuum device such as the chamber 2 are connected.
The inside of the robot chamber 8 is also evacuated so that the pressure is higher than that of the transfer chamber 10 and the pressure difference between the transfer chamber 10 and the transfer chamber 10 is within a certain range. The robot 7 has an arm 12 of a link mechanism capable of performing a linear operation and a rotational operation (R-θ operation), and a mounting plate 14 is provided on a hand 13 at the tip of the arm 12 for levitation control which constitutes magnetic levitation means 15. The electromagnet 16 is attached. In the case of FIG. 6, the magnetic levitation means 15 is composed of the levitation control electromagnet 16 and the levitation magnetic body 18 composed of a permanent magnet provided on the non-magnetic attachment plate 17 of the moving element 9. As the magnetic material 18, a magnetic material such as an iron piece may be used.

The magnetic levitation control of the mover 9 is performed by using a levitation magnetic body 18 provided on the mounting plate 17 of the mover 9 symmetrically in the front and rear and right and left, and each levitation of the mounting plate 14 of the robot hand 13. It is performed by controlling the current flowing through each of the levitation control electromagnets 16 so that the gaps between the magnetic bodies 18 and the levitation control electromagnets 16 provided at the corresponding positions are equal.
Specifically, the magnetic flux from the sensor provided near the levitation control electromagnet 16, that is, the levitation magnetic body 18 or the sensor target permanent magnet 23 provided on the mover 9, for example, a Hall element or the magnitude of the magnetic flux density is detected. The inductor type sensor whose inductance changes due to the change in the levitation distance (gap in the gravity direction) between each levitation magnetic body 18 and the levitation control electromagnet 16 due to weight change, pitching, or rolling of the mover 9, or movement. Positional deviations (horizontal gaps) in the advancing direction, guide direction, and yawing direction of each levitation magnetic body 18 and levitation control electromagnet 16 due to movement of the child 9 are detected, and when the two approach each other, the levitation control electromagnet Make sure that the gap between the two is always equal, either by reducing the current or by passing a current that creates a repulsive pole that separates the two. Kunar so each levitation control electromagnet 1
The current flowing through 6 is controlled.

The details of the mover 9 are as shown in FIGS. 4 and 5, and are formed in a frame shape by two non-magnetic frames 19, the rear mounting plate 17 and the front horizontal rod 20. The horizontal rod 20 is provided with a holding device 21 for an electrostatic chuck that extends forward and holds the work a by suction. Twelve permanent magnets are provided on the mounting plate 17 so as to be bilaterally symmetric with respect to the moving element 9, and the levitation magnetic bodies 18a, 1a for controlling levitation distance, pitching and rolling are provided.
8b, 18c and 18d are arranged symmetrically and guide / yaw magnetic members 22a, 22b and 22c, which control the traveling direction, guide direction and yawing direction of the permanent magnets and the like.
22d are arranged symmetrically, and the sensor target permanent magnets 23a, 23b, 23c and 23d are also arranged symmetrically.
A levitation control electromagnet 15 is attached to a mounting plate 14 of the hand 13 at a position opposed to the levitation magnetic body 18, and a guide / yaw control electromagnet (not shown) is provided at a position opposed to the guidance / yaw magnetic body 22. ) Is attached, and a magnetic sensor (not shown) is attached at a position facing the sensor target permanent magnet 23, and the magnetic force detected by the magnetic sensor is analyzed to determine the flying distance and tilted state of the moving element 9. The current of each control electromagnet is controlled so as to correct it. The holding device 21 may be a mechanical chuck that operates electrically, and a magnetic substance such as iron may be used as the guide / yawing magnetic substance 22. Further, for controlling the traveling direction, one permanent magnet may be provided in the center of the mounting plate 17 and an electromagnet for controlling the traveling direction may be provided on the mounting plate 14 for control.

Further, in order to supply power to the holding device 21 such as the electrostatic chuck through the vacuum partition 6, the primary transformer 25 connected to the AC oscillator 24 and the AC of the AC oscillator 24 are rectified to DC. A separation type transformer 29 is provided which is composed of a rectifying circuit 26 for conversion and a secondary transformer 28 connected to the holding device 21 via an airtight feedthrough 27. The primary transformer 25 is fixed to the mounting plate 14 of the hand 13, and the secondary transformer 28 is fixed to the mover 9 so as to face the primary transformer 25. The moving element 9 in the magnetically levitated state has its intermediate portion supported by the magnetically levitating means 15 in a cantilevered state, and the load fluctuation depending on whether or not the workpiece a is held by the holding device 21 at the tip thereof. The center of gravity moves due to the movement, but it is not preferable that the range of movement exceeds the range of effective magnetic action of the magnetic levitation means 15, and the range of movement is limited to the levitation magnetic bodies 18a or 18b and 18c of the magnetic levitation means 15. In order to limit the range L between 18d, the secondary transformer 28 is mounted as a counterweight behind the mounting plate 17 of the moving element 9 so that the moving element 9 does not increase in weight. The balance before and after 9 can be maintained regardless of load fluctuations. Reference numeral 30 is a sealed case that seals out gas from the secondary transformer 28.

An example of an exhaust circuit configuration for maintaining the differential pressure between the robot chamber 8 and the transfer chamber 10 within a substantially constant range is shown in FIG.
To be as listed, to connect the vent circuit 32 provided with a vent valve V ₃ with connecting the robot chamber 8 to the rotary pump 31 via a valve V _1, valve V ₂ the transfer chamber 10, V ₅ And a turbo molecular pump 34 via a valve V ₆ and a vent circuit 35 equipped with a vent valve V ₄ . Further, a differential pressure gauge 36 for measuring a differential pressure (P ₁ -P ₂ ) between the robot room 8 and the transfer room 10 is connected,
This electric signal is compared in the hysteresis comparators 37 and 38 to which the set value of the differential pressure ΔP is input, and the opening / closing of each valve is controlled by the signal obtained through the logic circuit 39 to which the exhaust or vent signal is input. Both rooms 8, 10
The differential pressure was maintained within a substantially constant range not only during exhaust but also during venting. An example of control of each valve is as shown in FIG. 8. During evacuation, the valves V ₁ and V ₂ are controlled to be opened / closed to evacuate the inside of the transfer chamber 10 to an ultra-high vacuum and the robot chamber 8 to a predetermined differential pressure. The internal pressure is controlled, and at the time of venting, the valves V ₃ and V ₄ are controlled to be opened and closed to increase the pressure inside the chamber while maintaining the differential pressure. Even if the transfer chamber 10 is in an ultra-high vacuum, if the pressure in the robot chamber 8 is controlled to about several hundred Pa, the vacuum partition 6 is less flexed and the hand 13 can be moved closer to the partition surface. With such a pressure in the robot chamber 8, the usual inexpensive lubricating oil can be used for lubricating the robot 7, the friction sliding portion of the robot 7 does not rise in temperature, and dust generated in the robot chamber 8 is It does not advance to the transfer chamber 10.

An example of the operation of the illustrated embodiment will be described below. First, the robot chamber 8 and the transfer chamber 10 are evacuated while maintaining a differential pressure between the chambers, and the hand 1 of the robot 7 is evacuated.
3, the floating control electromagnet 16 is excited to levitate the mover 9 in a cantilever state, and when the inside of the transfer chamber 10 is evacuated to an ultrahigh vacuum, the gate valve 40 is opened and a passage to, for example, an ultrahigh vacuum loading chamber is established. The transfer chamber is communicated via 41. Then, the hand 13 is linearly moved to advance the mover 9 into the loading chamber in which the work a is prepared, and the work a is received from the separation transformer 29 by the energized holding device 21 in the chamber, and the transfer chamber 10 is transferred. Go back in and gate valve 4
0 is closed, and the hand 13 is rotated to direct the moving element 9 to the next conveyance destination of the work a, for example, the etching chamber 3,
The gate valve 40 of the passage to the chamber 3 is opened, and the mover 9 holding the work a is advanced into the chamber 3 by the lead of the hand 13, where the work a is stored in the chamber 3 and then the transfer chamber 10 is held. Then, the gate valve 40 is closed. The mover 9 performs R-θ operation in the transfer chamber 10 without contact in accordance with the R-θ operation of the robot 7, and dust and gas generated from the robot 7 are separated from the transfer chamber 10 by the vacuum partition 6 in the robot chamber 8. Since it does not enter the transfer chamber 10, the sputtering chamber and the like connected to the transfer chamber 10 can be maintained in a clean and ultra-high vacuum state, and the vacuum partition 6 is not bent so much that it should be approached. Hand 1
3 can be moved, and the floating control of the mover 9 becomes easy. Further, the movement of the center of gravity of the mover 9 by holding the work a can be restricted within the range of the existence region of the magnetic levitation means 15 due to the secondary transformer 28 provided as a counterweight, and the special counterweight. Since it is not necessary to provide the above, it is possible to prevent the weight of the moving element 9 from increasing. Since a plurality of the levitation magnetic bodies 18 are attached to the mounting plate 17 provided on the moving element 9 in a front-rear and left-right distribution, the levitation magnetic elements 18 can be levitated against the front-rear, left-right inclination of the moving element 9. The inclination and the levitation distance are detected by the sensor target permanent magnet 23 and the magnetic sensor and are corrected to predetermined values by controlling the currents of the levitation control electromagnet 15 and the guide / yaw control electromagnet.

[0016]

As described above, according to the present invention, the chamber of the transfer device is divided into a robot chamber and a transfer chamber through a vacuum partition, and the robot hand and the transfer chamber are provided in the robot chamber. Since each moving element is provided with a magnetic levitation means for moving the moving element by magnetically levitating the moving element, it is possible to create an ultrahigh vacuum in the transfer chamber without causing a large bending of the vacuum partition, and the hand is vacuumed. A straight line
It is possible to rotate and improve the controllability of the magnetically levitated mover, not only linear operation but also rotational operation in the magnetically levitated state, and dust generated from the robot does not enter the transfer chamber, so it can be operated in a high vacuum atmosphere. It is convenient to use the robot, and there is no restriction on the structure or lubrication of the robot, which facilitates maintenance. Also, the transformer that feeds power to the work holding device is a separate type, and the secondary transformer is used to limit the movement of the center of gravity of the mover. Therefore, the movement of the center of gravity of the moving element can be limited without increasing the weight of the moving element, and the operability of the moving element is improved.

[Brief description of drawings]

FIG. 1 is a cutaway plan view of an embodiment of the present invention.

FIG. 2 is an enlarged cross-sectional view taken along line 2-2 of FIG.

FIG. 3 is a plan view of a main part of the robot shown in FIG.

FIG. 4 is an enlarged plan view of a mover.

FIG. 5 is a side view of FIG. 4;

6 is an enlarged view of the main part of FIG.

FIG. 7 is a diagram of an example of an exhaust circuit.

8 is an explanatory diagram of the operation of the exhaust circuit of FIG.

[Explanation of symbols]

a Work 1 Transport device 4
Cover 5 Indoor 6 Vacuum partition 7
Robot 8 Robot room 9 Mover 10
Transport room 12 Arm 13 Hand 1
5 magnetic levitation means 16 electromagnet for levitation control 18 levitation 2
1 Holding Device 22 Guide / Yawing Magnetic Material 23 Target Permanent Magnet for Sensor 25 Primary Transformer 28 Secondary Transformer 2
9 Separate type transformer

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Reference number within the agency FI Technical display location // H01L 21/203 S 9545-4M 21/3065 (72) Inventor Tadashi Takematsu Hagien, Chigasaki City, Kanagawa Prefecture 2500 In Japan Vacuum Technology Co., Ltd. (72) Inventor Ken Maehira 2500 Hagizono, Chigasaki City, Kanagawa Prefecture Japan Vacuum Technology Co., Ltd. (72) Inventor Shu Fujiki 2500 Hagien, Chigasaki City, Kanagawa Japan Vacuum Technology Co., Ltd.

Claims (4)

[Claims] 1. A chamber of a transfer device is divided into an airtight robot chamber containing a driving robot and a transfer chamber containing a moving element for transferring a work through a vacuum partition, and a hand of the robot is provided. A magnetic levitation transfer device for a vacuum device, characterized in that each of the moving elements is provided with a magnetic levitation means for magnetically levitating and moving the moving element. 2. A levitation magnetic body provided with the magnetic levitation means at an intermediate portion of the moving element, and a levitation device, wherein the moving element is provided in a longitudinal direction and a holding device for holding a work is provided at a tip portion thereof. And a primary transformer provided with the hand for feeding the holding device by magnetically levitating the moving element in a cantilevered support state, which comprises a levitation control electromagnet provided on the hand facing the magnetic material for use in the hand. The movement is performed through a separation type transformer of a secondary transformer housed in the case, and the movement of the center of gravity of the movement of the secondary transformer when holding the work of the holding device is performed by the magnetic levitation means. The magnetic levitation transfer device for a vacuum device according to claim 1, wherein the magnetic levitation transfer device is installed at a position within the range. 3. The magnetic levitation for a vacuum device according to claim 1, wherein the robot chamber is controlled to have a pressure higher than that of the transfer chamber, and the differential pressure between the two chambers is controlled to a certain value or less. Transport device. 4. The magnetic levitation means comprises a levitation magnetic body such as permanent magnets provided symmetrically on the left and right of the moving element.
4. The magnetic levitation transfer apparatus for a vacuum device according to claim 1, wherein the levitation control electromagnet is provided at a position corresponding to each levitation magnetic body of the hand, respectively.