JP2002355730A - Table positioning device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a new table positioning device that can realize positioning accuracy of nanometer order and a long stroke at the same time. SOLUTION: This table positioning device for moving and positioning a table 140 into a prescribed position is provided with a reciprocating base 12 installed to freely reciprocate along a prescribed axis to a stationary part 16, and the table 14 provided movably to the reciprocating base 12. The reciprocating base 12 is moved by a rough moving mechanism 22 so that the relative position of the reciprocating base 12 to the table 14 becomes a prescribed value, and the table 14 is moved to the reciprocating base 12 by a voice coil motor 30 on the basis of the deviation between the position of the table 14 to the stationary part 16, and a target position.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an apparatus for positioning a table of an ultra-precision machine tool or a semiconductor manufacturing apparatus.

[0002]

2. Description of the Related Art With the advancement of ultra-precision machine tools and semiconductor manufacturing equipment, the demand for higher performance of table systems, which are important components thereof, has been further increased. In particular, recently, high-speed and high-acceleration drive characteristics directly contributing to productivity improvement as well as mere positioning stop accuracy, nanometer order to target values for processing of 3D complicated shape parts and step & scan exposure. It is required to simultaneously realize the synchronous follow-up accuracy and the long stroke to cope with the enlargement of the machining target.

In general, a table system is composed of a guide element and a drive element, and the characteristics of these elements are important factors that affect the overall characteristics of the entire table system. In particular, in ultra-precision positioning table systems that require positioning accuracy on the order of nanometers, in order to eliminate the occurrence of nonlinear phenomena as much as possible and to achieve high-speed and high-acceleration driving, static air pressure guides, magnetic guides, and linear It is considered that the motor drive is adopted, and the support and drive by completely non-contact of the table is effective. However, in the case of a table system having such a structure, the static and dynamic characteristics in the table feed direction are linear motors, which are driving elements, because mechanical constraints such as friction of guide elements and screw elements do not act on the table. And the characteristics of the positioning controller. Therefore, for example, when a multi-pole linear synchronous motor is adopted as a driving element, a tracking error with respect to a target value is directly generated at the time of driving the table due to the thrust ripple.

[0004]

In order to solve such problems, conventionally, a method of estimating and compensating thrust ripple by an observer, a compensation method by sine wave approximation based on thrust ripple measurement, a compensation method based on a thrust ripple database, and the like have been proposed. Various correction methods have been proposed. However, these compensating methods are considered to be difficult to cope with all of the wide range of driving conditions of the table, especially at high speed and high acceleration / deceleration, due to the phase delay in the observer and the non-reproducibility of the table motion. . In addition, although a single-phase linear motor for semiconductor exposure equipment is being developed, a coil longer than the stroke of the table is required, increasing the coil inductance and heat generation due to the extension of the stroke, and space efficiency. It is thought that problems such as a decrease in cost and an increase in cost will occur.

An object of the present invention is to solve the above-mentioned problems of the prior art, and an object of the present invention is to propose a novel table positioning device capable of simultaneously realizing a positioning accuracy on the order of nanometers and a long stroke. And

[0006]

According to a first aspect of the present invention, there is provided a carriage provided so as to be capable of reciprocating along a predetermined axis with respect to a stationary part, and the carriage is provided along the axis. A first driving device for moving, a table provided movably with respect to the carriage in a direction parallel to the axis, and a second driving device for relatively displacing the table with respect to the carriage. In a table positioning device for moving and positioning the table to a predetermined position, a first detector for detecting a relative distance of the carriage with respect to the table, and a second detector for detecting a position of the table along the axis. And the second drive unit is controlled based on a deviation between the predetermined position and the position of the table detected by the second detector, and determines a relative distance between the table and the carriage. Predetermined And gist table positioning apparatus adapted to control said first drive unit such that the.

[0007]

Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. Referring to FIG. 1, a table positioning device 10 according to the present embodiment includes a stationary unit 1 along a linear bearing 18 extending in a predetermined axial direction.
6 and a table 1 provided to be relatively movable with respect to the carriage 12.
4 is provided. As a first driving device for causing the carriage 12 to reciprocate along the linear bearing 18, for example, a linear motor, a ball screw, and a coarse movement mechanism 22 using a combination of a servo motor and a belt or a wire described later are provided. On the other hand, the table 14 is guided by the aerostatic guide device 20 in a direction parallel to the axis of the linear bearing 18 in a non-contact manner with respect to the stationary portion 16, and the permanent magnets 32 and 34 fixed to the carriage 12 and the yoke The carriage 12 is reciprocally driven in a non-contact manner with respect to the carriage 12 by a voice coil motor 30 comprising a voice coil 38 fixed to the table 14 and electromagnetically interacting with the permanent magnets 32 and 34. The voice coil motor 30 may have a permanent magnet fixed to the table 14 and a voice coil attached to the carriage 12.

As a first detector for detecting the distance between the carriage 12 and the table 14, a laser including a laser oscillator 24a fixed to the table 14 and a laser receiver 24b fixed to the carriage 12 A displacement gauge 24 is provided. The laser displacement meter 24 has, for example, a resolution of 1.5 μm,
A triangulation laser displacement meter having a measurement range of 40 mm can be used. The coarse movement mechanism 22 is controlled by a control device described later so that the distance between the carriage 12 and the table 14 detected by the laser displacement meter 24 is constant.

As a second detector for detecting a position along the axis with respect to the stationary part 16 of the table 14,
Laser oscillator 26 fixed in place 16a of stationary part 16
a, and a laser interferometer 26 including a laser interferometer 26b fixed to the table 14. The laser interferometer 26 can be, for example, a laser heterodyne interferometer having a resolution of 1.25 nm and a measurement range of 40 m.

The driving mechanism of the positioning device according to the present invention comprises:
As shown in FIG. 1, the voice coil motor, which is basically a fine movement mechanism, is combined with a coarse movement mechanism to drive a non-contact supported table at an ultra-precise and high speed. It is intended to complement and to maximize its characteristics. The voice coil motor 30, which is a main component, has (1) a thrust proportional to the coil current. (2) Small coil inductance and excellent response characteristics. (3) There is no thrust ripple. (4) There is no magnetic attraction between the mover and the stator. (5) Since it has many features useful as a table drive system, such as a lightweight movable section,
This is the most suitable driving element for high-speed positioning. However, since it is difficult to form a uniform magnetic field over a long distance, the short stroke is a disadvantage as compared with other linear motors.

Therefore, in the table positioning apparatus 10 according to the present embodiment, the voice coil motor 30 having a short stroke and the coarse movement mechanism 22 having a sufficient stroke are combined, and the stators 32, 34, and 3 of the voice coil motor 30 are combined.
By following the table 14 while holding the 6 at a constant relative distance, ultra-precision and high-speed driving is realized over the entire long stroke. The number of permanent magnets and the coil length are independent of the table stroke,
Further, thrust can be controlled by only one current amplifier, which is effective for cost reduction.

In this embodiment, the major difference from the coarse / fine movement positioning mechanism using a piezoelectric element or the like according to the prior art is that there is no mechanical contact between the carriage 12 and the coarse movement mechanism 22 and the table 14. Is mentioned. Therefore, the table can be completely non-contact supported and driven, and at the same time, since the motion error of the coarse movement mechanism 22 is not directly transmitted to the table 14, the required accuracy of the coarse movement mechanism 22 can be reduced and the cost can be reduced. Further, the stroke of the voice coil motor 30 is much larger than that of the piezoelectric element, which is effective from the viewpoint of the stroke saturation of the fine movement mechanism.

FIGS. 2 and 3 show a more concrete embodiment of the table positioning apparatus according to the present invention.
In 3, 100 is a table positioning device, 102 is a carriage, 104 is a table, 106 is a linear bearing,
08 is an aerostatic guide, 110 is a laser interferometer, 11
Reference numeral 2 denotes a permanent magnet of the voice coil motor, 114 denotes a coil of the voice coil motor, 116 denotes a laser displacement meter, and 118 denotes a fixed base as a stationary unit.

In the present embodiment, a servo motor 122 fixed to a fixed base 118, a drive pulley 124 connected to an output shaft of the servo motor 122, and a floating pulley rotatably mounted on the fixed base 118 are used as the coarse movement mechanism. 126,
Both ends include a belt or wire 128 as a tension transmitting member fixed to the carriage 102 and stretched between the driving pulley 124 and the floating pulley 126.

Next, a preferred embodiment of a control device for the coarse movement mechanism 22 and the voice coil motor 30 will be described with reference to FIG. The control device 130 is a microcomputer or personal computer (hereinafter simply referred to as PC) 13 in which a central processing unit (CPU), ROM, RAM, and input / output ports are connected by a bidirectional bus.
5 is provided. The output of the digital counter of the laser interferometer 132 (reference numeral 26b in the embodiment of FIG. 1) is input to the PC 135 via the digital input / output unit 134.
The output of the digital counter is subjected to arithmetic processing in the PC 135, and the position of the table 14 is detected. The position of the table 14 is output as a feedback signal to the current amplifying device 138 for the voice coil motor 140 (reference numeral 30 in the embodiment of FIG. 1) via the D / A converter 136, and the movement target position of the table 14 is Is supplied to the coil (reference numeral 38 of the embodiment of FIG. 1) of the voice coil motor 140 (reference numeral 30 of the embodiment of FIG. 1).

The output of the laser displacement gauge 142 (reference numeral 24 in the embodiment of FIG. 1) is input to the PC 135 via the A / D converter 144. This A / D converter 144
Is output by the PC 135 to calculate the output of the carriage 1
The distance between 2 and the table 14 is detected. The distance between the carriage 12 and the table 14 is output as a feedback signal to the current amplifying device 148 for the servo motor 150 (reference numeral 122 in the embodiment of FIG. 3) via the D / A converter 146, and Table 12 and table 1
4 is supplied to the servomotor 150 (reference numeral 122 in the embodiment of FIG. 3).

In the embodiment shown in FIG. 4, the digital input / output unit 134, the PC 135, and the D / A converter 136 constitute a second control device, and the A / D converter 144, the PC
135 and the A / D converter 154 constitute a first control device.

FIG. 5 shows a preferred embodiment of the control logic. In FIG. 5, each symbol is as follows. _Xref : Position command _Kp : Proportional gain _Ki : Integral gain _Kf : Acceleration feed forward gain A: Phase lead compensation constant B: Phase lead compensation constant _Kg : Current loop gain L: Voice coil inductance R: Voice coil resistor I ... position K _p2 ... coarse adjustment mechanism of the position X _c ... coarse adjustment mechanism of mass X ... table of the voice coil current K _m ... voice coil motor thrust constant F ... voice coil motor of the generated thrust M ... table Position control proportional gain _Ki2 : Position control integral gain of coarse movement mechanism Gc _(S) : Motion characteristics of coarse movement mechanism

In the table positioning device according to the present embodiment, the voice coil motor 3
A second control device 152 for controlling the current supplied to 0;
Table 1 with voice coil motor stator (carriage 12)
There is provided a second control device 154 for following the movement of the first and second control devices 154, 152, as is evident from FIGS. 1, 4 and 5. .

In order to clarify the usefulness of the table positioning apparatus according to the present embodiment, the table positioning operation is performed by the following basic drive pattern, and the feedback data of the laser heterodyne interferometer obtained at that time is used. Based on this, the positioning characteristics were evaluated.

Micro-step drive An experiment was conducted on the response characteristics of the table 14 by micro-step drive of 20 nm and 5 nm. The measurement data includes about 5 resolutions corresponding to the resolution of the laser heterodyne interferometer 26b.
Although the fluctuation of nm was always included, it was confirmed that the table 14 followed the command value and moved stepwise. At the time of such a minute step drive, the coarse movement mechanism 2
2 is almost stopped, the motion characteristics of the table 14 are determined only by the characteristics of the voice coil motor 30,
Ultra-precision positioning becomes possible.

Low-Speed Driving In order to study low-speed driving characteristics of a table, which is important in an optical disc master disk exposure process, a constant-speed driving experiment at a speed of 100 nm per second was performed. In the experiment, the driving time was set to 1 second, and the target position of the table 14 after the driving was completed was 10 seconds.
0 nm. The tracking error of the table 14 was 5 nm during driving, and it was confirmed that continuous low-speed driving was realized. This shows the usefulness of the present embodiment in which the non-contact driving of the table 14 by the voice coil motor 30 having high responsiveness is realized.

Long Stroke Driving In order to suppress the occurrence of vibration due to rapid acceleration / deceleration, an experiment was conducted by generating a continuous jerk trajectory using a cosine function for long stroke positioning driving. Maximum speed 50m
the response of the table by the positioning drive of 80 mm exceeding the stroke of the voice coil motor 30 obtained at the setting of m / s and 200 mm / s, exceeding 30 mm;
The following error and the relative displacement between the table and the coarse movement mechanism were determined. The maximum acceleration was set so that the acceleration time was 0.08 seconds.

First, a large relative displacement occurs between the table 14 and the coarse movement mechanism 22 when the table 14 is accelerated or decelerated. The occurrence of relative displacement was confirmed. However, such a motion error of the coarse movement mechanism 22
It was confirmed by experiments that it had little adverse effect on the movement of No. 4. That is, it was experimentally confirmed that the transmission of the movement error of the coarse movement mechanism 22 to the table 14 was small. Further, it is confirmed that despite the movement of the coarse movement mechanism 22 when the table 14 is stopped, the positional deviation of the table 14 quickly converges, and almost no overshoot or residual vibration occurs. Was.
Further, the maximum tracking error when the table 14 is driven is about ± 20 nm even when the driving speed is 200 mm / s, and the table positioning device 10 according to the present embodiment has a sufficient performance for ultra-precise and high-speed driving of the table 14. It became clear that it had.

Having described the preferred embodiment of the invention,
It is obvious to those skilled in the art that the present invention is not limited to this, and various changes and modifications are possible. For example, in the above-described embodiment, the coarse movement mechanism 22 as the first driving device is used.
Was constituted by a servomotor 122, a driving pulley 124, a floating pulley 126, a belt or a wire 128, but the present invention is not limited to this, and a nut (not shown) fixed to the carriage 12 It can also be constituted by a drive mechanism including a ball screw (not shown) extending in the axial direction and engaging with the nut, and a servomotor (not shown) connected to the ball screw.

The first detector for detecting the relative distance of the carriage 12 with respect to the table 14 is not necessarily an essential component, but detects the position of the carriage 12 with respect to the stationary part 16 or the fixed base 118. Is also good. Such a carriage position detector includes a rotary encoder (not shown) for detecting the rotation of the servomotor 122 connected to the drive pulley 124 or the servomotor connected to the ball screw, and a rotary encoder along the axial direction. Carriage 1
And a linear scale (not shown) for detecting the position of No. 2.

Next, referring to FIGS. 6 and 7, the second embodiment of the present invention will be described.
An embodiment will be described. This embodiment is configured in the same manner as the first embodiment except that a magnetic damper capable of actively controlling the movement characteristics of the table, particularly the damping ability, is provided. In FIGS. 6 and 7, the same components as those in the first embodiment are denoted by the same reference numerals, and overlapping description will be omitted.

In FIG. 6, the table positioning device 10
Reference numeral 0 denotes a magnetic damper device 200. The magnetic damper device 200 is different from the table 104 in the first embodiment.
A conductor 202 extending parallel to the linear bearing 106 and the aerostatic guide 108 on the lower side of the table 204 extended laterally in comparison with Attached to form a magnetic field acting on the conductor 202. In this embodiment, as shown in FIG. 7, the magnet is a yoke 206 attached to the lower surface of the table 204 so as to surround at least a part of the conductor 202.
And coils 208 and 21 attached to yoke 206
It is an electromagnet having 0.

By supplying current to the coils 208 and 210, a magnetic circuit is formed around the yoke 206 and across the conductor 202. As described above, the magnetic field traversing the conductor 202 makes it possible to increase the moving characteristics of the table, particularly the damping ability, in a non-contact manner. In connection with this, in the related art, when positioning the table in a non-contact manner, there is a problem that the performance of keeping the table at a predetermined position, that is, the positioning rigidity of the table cannot be increased. Therefore, the non-contact type table positioning device has hardly been applied to a machine tool or the like in which a large disturbance acts on the table. According to the present embodiment, the positioning rigidity of the table 204 can be increased. For example, even when a disturbance such as a processing force acts on the table 204, the table 204 can always be fixed to a predetermined value with high positioning accuracy. It becomes possible.

Further, a magnetic field intensity control device (not shown) is provided, and the coil 208,
It is possible to actively control the damping capability of the table 204 by controlling the value of the current supplied to the 210. For example, when fast-forwarding the table 204, the coils 208, 2
10 to reduce the damping capacity of the table 204 by reducing the current supplied to the table 10, thereby improving the acceleration performance of the table 204, and increasing the control gain of the table 204 while increasing the current supplied to the coils 208 and 210 at the time of stopping. To As described above, the control gain of the table 204 is also controlled based on the current supplied to the coils 208 and 210, so that the table 204 can be controlled at high speed and with high accuracy.
Can be positioned. Thus, the coils 208, 2
In controlling the strength of the magnetic field across conductor 202 by controlling the value of the current to 10, the magnetic field strength controller may include a power supply to supply current to coils 208, 210.

In the embodiment shown in FIGS.
Although the magnet forming the magnetic field across the two was formed from an electromagnet including a yoke 206 and coils 208 and 210, the present invention is not limited to this, and the conductor may be formed so as to form a magnetic field across the conductor 202. Permanent magnets (not shown) may be provided facing each other on both sides of the table 202 and attached to the lower surface of the table 204. In this configuration, the conductor 202 is desirably formed so as to be able to move forward and backward between the permanent magnets in the vertical direction in FIG. 7, and the magnetic field intensity control device moves the conductor 202 in the vertical direction in FIG. And a driving device (not shown) for relatively positioning.

[Brief description of the drawings]

FIG. 1 is a conceptual diagram of a table positioning device according to the present invention.

FIG. 2 is a side view of a first embodiment in which the table positioning device of the present invention is embodied more specifically.

FIG. 3 is a plan view of the table positioning device of FIG. 2;

FIG. 4 is a block diagram showing a control device of the table positioning device of the present invention.

FIG. 5 is a control logic of a control device of the table positioning device according to the present invention.

FIG. 6 is a plan view of a table positioning device according to a second embodiment of the present invention.

FIG. 7 is a partial cross-sectional view of the magnetic damper device taken along the line VII-VII in FIG.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 10 ... Table positioning device 12 ... Carriage table 14 ... Table 16 ... Stationary part 18 ... Linear bearing 18 20 ... Air static pressure guide device 24 ... Laser displacement meter 26 ... Laser interferometer

──────────────────────────────────────────────────続 き Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat ゛ (Reference) G05D 3/12 305 B23Q 1/26 EF term (Reference) 3C048 BB01 BB12 BC02 CC07 DD01 EE00 5H303 AA05 DD01 DD04 DD08 DD11 DD19 DD24 DD25 DD28 EE03 EE08 FF07 GG06 GG13 HH02 HH05 HH07 HH09 KK37 LL03

Claims (22)

[Claims] 1. A carriage provided so as to be able to reciprocate along a predetermined axis with respect to a stationary portion, a first driving device for moving the carriage along the axis, and a carriage. A table provided movably provided in a direction parallel to the axis, and a second drive device for relatively displacing the table with respect to the carriage, a table positioning apparatus for moving and positioning the table to a predetermined position In the apparatus, a first detector for detecting a relative distance of the carriage with respect to the table, a second detector for detecting a position along the axis of the table, the predetermined position, and the second The second driving device is controlled based on a deviation from the position of the table detected by a detector, and the first driving device is controlled so that a relative distance between the table and the carriage becomes a predetermined value. You Table positioning device. 2. The first driving device according to claim 1, wherein the first driving device fixed to the stationary part includes a servomotor, and a tension transmitting member stretched between the servomotor and the carriage. The table positioning device according to claim 1, further comprising: 3. The table positioning device according to claim 1, wherein the second driving device includes a voice coil motor. 4. The voice coil motor includes a voice fixed to the carriage and a voice fixed to the table and movably provided in the predetermined axial direction by an electromagnetic interaction between the permanent magnet and the permanent magnet. The table positioning apparatus according to claim 3, further comprising a coil. 5. The table positioning device according to claim 1, wherein the table is guided by an aerostatic guide device. 6. A carriage provided so as to be able to reciprocate along a predetermined axis with respect to a stationary part, a first driving device for moving the carriage along the axis, and a carriage. A table provided movably provided in a direction parallel to the axis, and a second drive device for relatively displacing the table with respect to the carriage, a table positioning apparatus for moving and positioning the table to a predetermined position In the apparatus, the second driving device drives the table in a non-contact manner with respect to the carriage. 7. The table positioning device according to claim 6, wherein the second driving device includes a voice coil motor. 8. The voice coil motor includes a voice fixed to the carriage and a voice fixed to the table and provided to be movable in the predetermined axial direction by an electromagnetic interaction between the permanent magnet and the permanent magnet. The table positioning device according to claim 7, further comprising a coil. 9. The voice coil motor, wherein a voice is provided movably in the predetermined axial direction by electromagnetic interaction between the permanent magnet fixed to the table and the permanent magnet fixed to the carriage. The table positioning device according to claim 7, further comprising a coil. 10. A nut in which the first driving device is fixed to the carriage, a ball screw extending in the axial direction and engaging with the nut, and a servomotor connected to the ball screw. The table positioning device according to any one of claims 6 to 9, further comprising: a carriage position detector configured to detect a position of the carriage along the axis. 11. The table positioning apparatus according to claim 10, wherein the carriage position detector includes a rotary encoder that detects rotation of the servomotor. 12. The table positioning device according to claim 10, wherein the carriage position detector includes a linear scale extending in the axial direction. 13. The table positioning device according to claim 1, wherein the first driving device includes: a servomotor fixed to the stationary portion; and a tension transmission member stretched between the servomotor and the carriage. The table positioning apparatus according to any one of claims 6 to 9, wherein the apparatus further includes a carriage position detector that detects a position of the carriage along the axis. 14. The table positioning device according to claim 13, wherein the carriage position detector includes a rotary encoder that detects rotation of the servomotor. 15. The table positioning device according to claim 13, wherein the carriage position detector includes a linear scale extending in the axial direction. 16. The apparatus according to claim 16, wherein the table positioning device further comprises:
A first detector that detects a relative distance of the carriage with respect to the table, a second detector that detects a position of the table along the axis, the predetermined position, and the second detector Controlling the second driving device based on the detected deviation from the position of the table, and controlling the first driving device so that the relative distance between the table and the carriage becomes a predetermined value. The table positioning device according to claim 6, wherein 17. The apparatus according to claim 17, wherein the first driving device includes a nut fixed to the carriage, a ball screw extending in the axial direction and engaging with the nut, and a servomotor connected to the ball screw. 17. The table positioning device according to claim 16, comprising: 18. The table positioning device according to claim 6, wherein the table is guided by an aerostatic pressure guide device. 19. The apparatus according to claim 1, further comprising a magnetic damper device including a conductor extending in a direction of movement of the table, and a magnet attached to the table for forming a magnetic field acting on the conductor. 19. The table positioning device according to any one of items 18. 20. The table positioning device according to claim 19, wherein said magnetic damper device includes a magnetic field intensity control device for controlling the intensity of a magnetic field traversing said conductor. 21. The table positioning device according to claim 20, wherein the magnet is an electromagnet, and the magnetic field strength control device controls a current value supplied to the electromagnet. 22. The magnet, wherein the magnet is a permanent magnet disposed on both sides of the conductor, the conductor is disposed in a space between the permanent magnets so as to be able to advance and retreat, and the magnetic field intensity control device is configured to 21. The table positioning device according to claim 20, wherein a relative position of the table with respect to the permanent magnet is controlled.