JPH0886611A - Positioning apparatus for table - Google Patents

Abstract

PURPOSE: To realize a stable and excellent high-speed positioning apparatus by setting a detecting means which offsets adverse influential factors of the minute vibration phenomenon of a mechanical system onto measuring signals of a laser length-measuring system. CONSTITUTION: A first acceleration sensor 22 is set to detect minute vibrations of a mechanical system on the side of a table 150. A second acceleration sensor 24 is also set to detect minute vibrations of a mechanical system of a length- measuring means measuring the distance to the table 150. Moreover, a vibration- correcting part 10 is provided to correct the measured distance of the position of the table 150 by detecting a difference of the minute vibrations of both mechanical systems of the table 150 and length-measuring means when receiving signals from the first, and second acceleration sensors 22 and 24.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to improvement of unstable positioning operation due to mechanical vibrations or shocks generated from the outside or inside of the apparatus in a table which is moved on the X plane or the Y plane with high accuracy.

[0002]

2. Description of the Related Art An example of the prior art is a table positioning device which is installed on a vibration isolation table and measures the position of a table by the interference of laser beams.
This is a case in which the movement of 50 is rapidly converged in a short time. This will be described with reference to FIGS. 4 and 5.
As shown in FIG. 4, the configuration of this device includes a vibration isolation table 100,
Base 102, guide 110, and linear motor 120
, Table 150, mirror 152, interferometer base 31
2, an interferometer 310, a laser light source base 302, a laser light source 300, a laser length measuring and counting unit 320, a servo controller 220, a power amplifier 240, and a control unit 200.

The vibration isolation table 100 is an anti-vibration table for suppressing external vibration, and the entire positioning device is installed on this table. The base 102 is a rigid base that forms a horizontal reference plane when the table 150 moves. The guide 110 is a rail on which the table 150 is placed and which guides the plane slide in the Y direction 151.
It is installed on 02. The table 150 is used as a stand on which, for example, a silicon wafer is placed and moved to a desired position. The table 150 is placed on the guide 110, and is guided on the guide rail horizontally in the Y direction 151. Glide freely. This table is 0.1 μm
Positioning is performed with a degree of precision. This table 150
Although not shown in the figure, a compensating mechanism such as yawing (Yawing) and this driving means are provided under the to form an integrated structure.

The linear motor 120 is a driving means by a linear motor that generates a linear thrust, and is the table 1 described above.
50 is moved forward / backward in the Y direction, and infinite resolution positioning drive can be performed by changing the drive current to the linear motor 120. Also, table 15
After 0 is positioned, the drive current becomes zero, and the table 150 becomes stationary due to its own weight. Normally, since a very small displacement occurs, the linear motor 120 always performs fine positioning control.

Interferometer base 312 and laser light source base 302
Is a rigid base for aligning the optical axis of the laser beam 300a from the laser light source 300 with one axis.
Laser light source 300, mirror 152, and interferometer 310
Detects and measures the position of the table 150. The laser light source 300 is a continuous point beam laser beam 300a.
Is emitted in parallel to the Y direction and is applied to the mirror 152. The mirror 152 is a mirror for reflecting the laser beam 300 a from the laser light source 300, and the table 1
It is fixed vertically at 50. The interferometer 310 receives the laser beam 300a, branches into two inside, transmits a part as it is, and outputs it to the mirror 152.
The light rays reflected from and returning from the laser light are caused to interfere with each other to generate interference fringes, the interference fringes are converted into an electric signal, and the interference fringe signal 310a is supplied to the laser length measuring and counting unit 320.

The laser length measuring / counting unit 320 counts the moving distance of the table 150 from the interference fringes. The laser measuring / counting unit 320 receives the interference fringe signal 310a and counts the number of pulses according to the moving direction to determine the distance. Measure and measure this signal 3
20a is supplied to the servo controller 220.

The servo controller 220 performs feedback control of the linear motor 120 by means of PID control means, and generates and outputs signals for controlling driving such as acceleration, constant speed, deceleration and inching in an optimum state. 5, the set value 222, the deviation detection unit 224, and the amplification unit 2
26 and a PID calculator 228. Also,
The servo controller 220 is used with a high amplification degree in order to move the inching movement of the table 150 at high speed in a short time of about several milliseconds to converge the positioning. The set value 222 is a register set by the control unit 200 and sets the moving position of the table 150.
This value is supplied to one input end of the deviation detection unit 224.
The deviation detection unit 224 receives the length measurement signal 320 a of the table 150 at the current time from the laser length measurement counting unit 320, subtracts it from the set value 222, and supplies the result to the amplification unit 226. The PID calculation unit 228 gives an amplification condition so as to perform PID control calculation and converge in a short time. Upon receiving the output drive signal 220a of the amplification unit 226, the PID calculation unit 228 receives P
The PID signal obtained by the differential / integral calculation of the ID control is supplied to the input end of the amplification section 226. Here, the control unit 200 sets desired values for the integration constant and the differential constant used for the PID control. The amplification unit 226 receives the deviation signal from the deviation detection unit 224 and the PID signal, adds the both, and amplifies the drive signal 220a at a desired magnification to generate the drive signal 220a.
Supply to 40. Here, the amplification ratio of the amplification section 226 is
A desired value is set by the control unit 200.

The control section 200 receives a movement position command from the outside and supplies various parameters to the servo controller 220 to control the servo controller 220 in the optimum state. The power amplifier 240 receives the drive signal 220a, converts it into a drive signal corresponding to the linear motor 120, and amplifies the power,
The linear motor 120 is supplied to drive the table 150.

[0009]

As described above, in this apparatus, a high loop amplification factor is used in order to move the inching of the table 150 at high speed in a short time of about several milliseconds to converge the positioning. The drive of the linear motor 120 is feedback-controlled. However, the vibration phenomenon of the mechanical system caused by the high speed acceleration / deceleration control of the table 150 is
The measurement signal 320a is adversely affected by the laser measurement system.
However, the defective vibration element other than the actual position information of the table 150 is included. That is, a minute mirror 152 of about μm
The base 102, the interferometer base 312, and the laser light source base 302 are natural vibration elements of several tens to several hundreds Hz. Under the influence of these natural vibrations, the value of the length measurement signal 320a includes a defective vibration element. As a result, the PID control by the servo controller 220 causes a problem that it takes a long time to converge to a desired permissible range, or a problem that an oscillation phenomenon occurs due to a feedback loop system without convergence occurs. This may lead to unstable operation such as. For this reason, there is a situation in which the loop amplification factor for high-speed movement in a short time is lowered and used, which often causes a difficulty in using high-speed positioning, which is not preferable.

Therefore, the problem to be solved by the present invention is to provide a detecting means for canceling the adverse effect that the minute vibration phenomenon of the mechanical system has on the length measurement signal 320a of the laser length measuring system, to provide stable and good operation. The object is to realize a high-speed positioning device.

[0011]

In order to solve the above-mentioned problems, in the structure of the present invention, the first acceleration sensor 22 for detecting the minute vibration of the mechanical system on the table 150 side is provided to measure the position of the table. A second acceleration sensor 24 that detects a minute vibration of the mechanical system on the length measuring means side is provided, and signals from the first acceleration sensor 22 and the second acceleration sensor 24 are received, and both of the table 150 side and the length measuring means side are received. The vibration correction unit 10 for detecting the difference between the minute vibrations of the mechanical system and correcting the length measurement of the position of the table 150 is a constituent means. As a result, more accurate deviation value information can be obtained by detecting and correcting a slight change in the positional relationship between the table driving means that moves the table 150 and the length measuring means that measures the position of the table. Thus, the positioning of the table 150 can be realized by the stable feedback control.

As a more specific means, the table 15
First acceleration sensor 2 that detects minute vibrations of the mechanical system on the 0 side
2 is fixed to the base 102 or the mirror 152,
A second acceleration sensor 24 that detects a minute vibration of a mechanical system on the side of a length measuring unit that measures the position of the table is fixedly provided on the interferometer 310, and signals from the first acceleration sensor 22 and the second acceleration sensor 24 are provided. In response, the difference between the minute vibrations of both the mechanical system on the side of the table 150 and the side of the length measuring means is detected to detect the table 15
The vibration correction unit 10 for correcting the length measurement at the position of 0 is provided as a constituent means. As a result, the first acceleration sensor 22 and the second acceleration sensor 22
The acceleration sensor 24 allows the position difference information 10 between both sensors to be detected.
p is obtained, and more correct deviation value information with respect to the target movement point is obtained from this, whereby stable positioning of the table 150 by feedback control can be realized.

[0013]

The first acceleration sensor 22 or the second acceleration sensor 24 has a function of detecting a mechanical system vibration phenomenon caused by high-speed acceleration / deceleration control of the table 150 and a vibration received from the outside of the apparatus. The vibration correction unit 10 receives both acceleration signals 22a and 24a from the first acceleration sensor 22 and the second acceleration sensor 24, and integrates both signals to detect the speed difference information 10v and the position difference information 10p. It has an effect. By the first acceleration sensor 22, the second acceleration sensor 24, the vibration correction unit 10, and the servo controller 220, more accurate deviation value information with respect to the target moving point can be obtained from the position difference information 10p between the two sensors. The role is to be able to form a feedback loop system capable of stable and convergent positioning and convergence in a short time.

[0014]

The embodiment of the present invention is based on a base 102 and an interferometer 31.
0 is provided with a high-sensitivity acceleration sensor to detect a minute vibration phenomenon of both mechanical systems, thereby canceling the length measurement signal 320a of the laser length measurement system to realize a stable high-speed positioning device. . This will be described with reference to FIGS. 1 and 3. As shown in FIG. 1, the configuration of the present device is a configuration in which a first acceleration sensor 22, a second acceleration sensor 24, and a vibration correction unit 10 are added to the conventional configuration.

The first acceleration sensor 22 is a high-sensitivity acceleration sensor which is attached to the side surface of the base 102 and detects vibration acceleration in the Y direction 151. Vibration accompanying high-speed acceleration / deceleration of the table 150, or external vibration isolation table 100
The vibrations transmitted via the vibrations give vibrations to the base 102. After detecting the vibration acceleration, the base acceleration signal 22a is supplied to the vibration correction unit 10.

The second acceleration sensor 24 is a high-sensitivity acceleration sensor which is attached to the interferometer 310 and detects vibration acceleration in the Y direction 151. The high-speed acceleration / deceleration of the table 150 or the vibration from the outside is transmitted to the interferometer base 312 and gives the vibration of the interferometer 310. After detecting the vibration acceleration, the interferometer acceleration signal 24a is supplied to the vibration correction unit 10.

The vibration compensating section 10 includes both acceleration signals 22 from the first acceleration sensor 22 and the second acceleration sensor 24.
In response to a and 24a, the speed difference information 10v and the position difference information 10p are output. That is, as shown in FIG. 3, the integrators 12 and 13 perform integration to obtain velocity information.
The subtractor 14 calculates the difference between the speeds of the two and then supplies the speed difference information 10v to the servo controller 220. Further, receiving the speed information of both of them, the integrator 1
The position information is integrated by 6 and 17 to obtain the position information, the subtracter 18 calculates the difference, and the position difference information 10p is supplied to the servo controller 220.

The servo controller 220 is provided with a subtractor 225 in addition to the conventional structure to add control for canceling out defective vibration elements contained in the length measurement signal 320a. That is, the subtractor 225 receives the deviation signal from the deviation detection unit 224 at one input end, receives the position difference information 10p from the calculation vibration correction unit 10 and subtracts it to obtain the deviation value from the target movement point. After being taken out, it is supplied to the amplification unit 226. The PID calculator 228 receives the speed difference information 10v from the vibration corrector 10 and uses it as a parameter signal for accelerating the driving of the linear motor 120 so that the speed difference converges in a shorter time. By performing these offset controls, it is possible to offset adverse factors that affect the length measurement signal 320a of the laser length measurement system, and as a result, stable positioning can be achieved in a short time.

In the above description of the embodiment, the first acceleration sensor 22 is attached to the side surface of the base 102 for detection, but this attachment position is directly attached to the mirror 152 for detection, as shown in FIG. It may be configured as
It can be carried out in the same manner.

Further, in the description of the above embodiment, 15 in the Y direction.
Although the configuration example of the positioning device that cancels the minute vibration of the mechanical system in the case of the table 150 that moves in one uniaxial direction has been described, the driving unit that moves in both the vertical X direction and the horizontal Y direction is described. The table 150 provided may be used and can be similarly implemented.

Further, in the above description of the embodiment, the case where the laser beam is used as the length measuring means of the table 150 is explained, but in the case of the length measuring means other than the laser,
The same can be implemented as long as the positioning device has a structure capable of canceling the adverse effect of the mechanical vibration caused by the mechanical measurement detecting means and the table 150 on the measured signal.

[0022]

Since the present invention is configured as described above, it has the following effects. The first acceleration sensor 22, the second acceleration sensor 24, and the vibration correction unit 10 obtain the positional difference information 10p between the two sensors, and from this, the deviation value from the target movement point is obtained. The effect that the positioning can be converged in a shorter time is obtained. As a result, the microvibration phenomenon of the mechanical system cancels out the adverse effect given to the length measurement signal 320a of the laser length measurement system, and stable and high-speed positioning becomes possible.

[0023]

[Brief description of drawings]

FIG. 1 is a first configuration diagram of a table positioning device of the present invention, in which a highly sensitive acceleration sensor is provided on a base 102 and an interferometer 310 to cancel a microvibration phenomenon of a mechanical system of both.

FIG. 2 is a second configuration diagram of a table positioning device of the present invention in which a highly sensitive acceleration sensor is provided on a mirror 152 and an interferometer 310 to cancel a microvibration phenomenon of a mechanical system of both.

FIG. 3 is a control configuration diagram of a servo controller 220 including the vibration correction unit 10 according to the present invention.

FIG. 4 is a configuration diagram of a conventional table positioning device by laser measurement.

FIG. 5 is a control configuration diagram of a conventional servo controller 220.

[Explanation of symbols]

 10 vibration correction part 10p position difference information 10v speed difference information 12, 13, 16, 17 integrator 14, 18, 225 subtractor 22 first acceleration sensor (vibration detection means) 22a, 24a acceleration signal 24 second acceleration sensor (vibration) Detecting means) 302 Laser light source base 100 Vibration isolation base 102 Base 110 Guide 120 Linear motor 150 Table 151 Y direction 152 Mirror 200 Control unit 220 Servo controller 222 Set value 220a Drive signal 224 Deviation detection unit 226 Amplification unit 228 PID calculation unit 240 Power amplifier 300 Laser light source 300a Laser beam 310 Interferometer 310a Interference fringe signal 312 Interferometer stand 320 Laser length measurement counter 320a Length measurement signal

Claims (2)

[Claims] 1. An apparatus for positioning a table (150), comprising table driving means for horizontally moving the table (150) in one axis direction and length measuring means for measuring the position of the table. The second vibration detecting means (24) for detecting the minute vibration of the mechanical system on the side of the length measuring means for measuring the position of the table is provided with the first vibration detecting means (22) for detecting the minute vibration of the mechanical system on the side of (150). ) Is provided, and the first vibration detecting means (22) and the second vibration detecting means (2) are provided.
A vibration correction unit (10) for receiving the signal from the table (4) and detecting the difference between the minute vibrations of the mechanical systems on the table (150) side and the length measuring means side to correct the length measurement of the position of the table (150). )
A table positioning device characterized by being provided with the above. 2. On one table (150) installation side, a mirror (152) fixed to the table (150) and measuring this position, and a linear motor (120) for horizontally driving the table (150) in one axis direction. ) And a base (102) on which the whole is placed, and a laser light source (300) and an interferometer 310 are provided on the side for measuring the position of the other table (150), and the table (150) is provided. In the device for positioning the table, a first acceleration sensor (22) for detecting minute vibrations of the mechanical system on the table (150) side is fixedly provided on the base (102) or the mirror (152) to measure the position of the table. The interferometer (31) is provided with a second acceleration sensor (24) for detecting minute vibrations of the mechanical system on the length measuring means side.
0) or the second acceleration sensor (24) is fixedly provided on the interferometer base (312) and receives signals from the first acceleration sensor (22) and the second acceleration sensor (24). Then, a vibration correction unit (1) for correcting the length measurement at the position of the table (150) by detecting the difference between the minute vibrations of both the mechanical systems on the table (150) side and the length measuring means side.
0) is provided and the above is provided, The table positioning device characterized by the above.