JPH11264444A - Vibration eliminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To effectively suppress the vibration of a vibration eliminating table caused by movement of a gravity center by feedforward inputting a stage target value or that matching an actuator and a vibration eliminating controller out of values operated based on the stage target value, to the vibration eliminating controller. SOLUTION: A target speed to be feedforwarded to a rotation displacement control system of a vibration eliminating table 15 is integrated by integral characteristics of an air spring so that the feedforward of the target speed is equivalent to the application of the rotation torque proportional to the target position of a stage 16 to the vibration eliminating table 15. The feedforward input of the target speed can offset the rotation moment generated by the moving of the stage 16 so that the vibration of the vibration eliminating table 15 can be effectively suppressed. The target speed is feedforward inputted only in the position control system in the rotation direction so as to give no inferior affect on the operation in the vertical direction.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a precision device equipped with a positioning device such as an XY stage, for example, a vibration isolator used in a semiconductor exposure apparatus, and a vibration caused by the movement of the device mounted on the device. The present invention relates to an improvement of an anti-vibration device capable of effectively suppressing noise.

[0002]

2. Description of the Related Art In an apparatus in which an optical microscope, an XY stage for exposure, and the like are mounted on an anti-vibration table, it is necessary to remove vibrations transmitted from the outside as much as possible. Further, in the case of the XY stage for exposure, an intermittent operation called step-and-repeat or step-and-scan is provided as a drive mode,
It must also be noted that the repeated steps or scan vibrations themselves generate a vibration of the anti-vibration table. It is impossible to perform exposure in a state where this vibration does not subside, and the anti-vibration table provides a well-balanced vibration control against external vibration and a vibration control against forced vibration caused by the motion of the mounted equipment itself. Is required.

[0003] In addition, vibration isolators are classified into passive vibration isolators and active vibration isolators. In order to meet demands for high-precision positioning, high-accuracy scanning, high-speed movement, and the like for devices mounted on the vibration isolators, they have recently been developed. Have a strong tendency to use active vibration isolators. Actuators for driving the vibration isolation table include an air spring, a voice coil motor, and a piezoelectric element.

Hereinafter, an air spring type vibration damping device using an air spring as an actuator will be described. FIG. 5 shows the configuration of a conventional air spring type vibration damping device. In FIG. 5, 1
And 8 are air spring type support legs, 2 is a servo valve for supplying and exhausting air of operating fluid to the air spring 3, 9 is a servo valve for supplying and exhausting air of operating fluid to the air spring 10,
Reference numerals 4 and 11 denote an anti-vibration table position sensor for measuring the vertical displacement of the anti-vibration table 15 at the measurement point, reference numerals 5 and 12 denote mechanical springs for preloading, and reference numeral 6 denotes viscosity of the air spring 3 and the mechanical spring 5 for preloading. A viscous element, 13 is a viscous element expressing the viscosity of the air spring 10 and the mechanical spring 12 for preload, 7 and 14 are acceleration sensors, 16 is a stage which operates horizontally on a vibration isolation table 15, and 17 is a horizontal direction of the stage. Stage position sensor for measuring the displacement, 18 a motor for driving the stage, 19 a displacement amplifier for amplifying the stage displacement, 20 a stage target position generator, 21 a PID compensator, 22 an amplifier, and 23 and 24 vibration isolation A displacement amplifier for amplifying the displacement of the table 15, 25 is a displacement decomposer, and 26 and 27 are PI
Compensators, 28 and 29 are filters, 30 is an acceleration decomposer, 31 is a thrust distributor, 32 and 33 are amplifiers, 34
Reference numeral denotes a vibration damping target position setting device, and reference numeral 40 denotes a sequence controller for controlling the operation of the stage 16. The stage position sensor 17, the displacement amplifier 19, the PID compensator 21, and the amplifier 22 constitute a stage controller. Anti-vibration table position sensors 4 and 11, displacement amplifiers 23 and 24, displacement decomposer 25,
The PI compensators 26 and 27, the filters 28 and 29, the acceleration decomposer 30, the thrust distributor 31, and the amplifiers 32 and 33 constitute a vibration isolation table controller. Numerals 1 to 17 are schematic diagrams when the apparatus is viewed from the side, and the air spring type support legs 1 and 8 support the vibration isolation table 15 in the vertical direction. Here, P of the PID compensator 21 means proportional, I means integral, and D means differential operation. In addition, P of the PI compensators 26 and 27 means proportional, and I means integral operation.

The operation of the air spring type vibration damping device shown in FIG. 5 will be described. The outputs of the acceleration sensors 7 and 14 are supplied to filters 28 and 29 having predetermined appropriate gains and time constants, respectively.
To the acceleration decomposer 30. here,
The two inputs are subjected to a 2 × 2 matrix operation to pass the vertical acceleration of the vibration isolation table 15 and the center of gravity of the vibration isolation table 15 to the stage 1.
6 is decomposed into angular acceleration in the pitching direction with respect to the operation direction 6, and is fed back negatively to the preceding stage of the thrust distributor 31. Damping is added by this acceleration feedback loop.

[0006] The outputs of the anti-vibration table position sensors 4 and 11 pass through displacement amplifiers 23 and 24, respectively.
5 is input. Here, the matrix is decomposed into a vertical displacement of the vibration isolation table 15 and a rotational displacement in the pitching direction with respect to the operation direction of the stage 16 through the center of gravity of the vibration isolation table 15 by a 2 × 2 matrix operation. The anti-vibration table target position setting device 34 sets the target positions of the vertical displacement and the rotational displacement, and a deviation signal between these target positions and the output of the displacement decomposer 25 passes through PI compensators 26 and 27. This is input to the thrust distributor 31. Here, the target value of the thrust in the rotation direction in the pitching direction with respect to the operation direction of the stage 16 through the vertical direction and the center of gravity of the vibration isolation table 15 is set as the drive target value of the air springs 3 and 10 by a 2 × 2 matrix operation. Distribute. The distributed drive target values are converted into drive currents for servo valves 2 and 9 by amplifiers 32 and 33, respectively.
The pressure in the air springs 3 and 10 is adjusted by the opening and closing of the valves of FIGS.
Can be held at the desired position set in the above step without a steady-state deviation. The PI compensator 26 operates as a control compensator for the vertical displacement of the vibration isolation table 15, and the PI compensator 27 operates as a control compensator for the rotational displacement of the vibration isolation table 15.

Further, the output of the stage position sensor 17 passes through a displacement amplifier 19, and is output to a stage target position generator 20.
Is different from the target position signal of the stage 16 generated by PI
It becomes the input of the D compensator 21. The output of the PID compensator 21 drives the stage 16 via the motor 18 through the amplifier 22. Here, the stage target position generator 20 receives a stage position command value and a stage movement start command from the sequence controller 40, and generates a stage target position signal based on these inputs.

In the air spring type vibration damping device shown in FIG. 5, the compensation is performed by disassembling the vibration mode into the rotation direction in the vertical direction and the rotation direction of the pitching direction with respect to the movement direction of the stage 16 through the center of gravity of the vibration damping table 15. Thereby, there is an advantage that the gain adjustment of the PI compensator becomes easy.

[0009]

However, when the stage 16 moves, the center of gravity of the anti-vibration table 15 and the whole mounted on the anti-vibration table move, causing the vibration of the anti-vibration table 15. The conventional feedback compensation has a drawback that the vibration of the vibration isolation table due to the movement of the center of gravity cannot be effectively suppressed.

Further, in the active vibration isolator, when the position of the center of gravity changes due to the movement of the stage, the actuator is driven so as to correct the inclination of the vibration isolation table. However, the higher the stage movement speed, the greater the amount of tilt of the anti-vibration table. If the position control loop gain is increased to correct this tilt, floor vibrations are more likely to be transmitted to the anti-vibration table. Off occurs.

An object of the present invention is to eliminate the problems of the prior art in a vibration isolator.

[0012]

In order to achieve the above object, in a first aspect of the present invention, a stage target value such as a target position, a target speed or a target acceleration of a stage, In addition, a value calculated according to the stage target value according to the configuration of the actuator and the anti-vibration table controller is fed forward to the anti-vibration table controller. For example,
For an air spring type anti-vibration device as shown in FIG. 5 in which an air spring also serves as the actuator, a target speed of the stage or a value obtained by integrating a drive signal of the stage is input to the anti-vibration table controller by feedforward input. I do. When the actuator is a voice coil motor, a stage target position is fed-forward input as the stage target value.

In a preferred embodiment of the present invention, in a pneumatic spring type vibration isolator in which an air spring also serves as the actuator, a value applied to a drive signal of a servo valve is vibration-isolated in a pitching direction with respect to a stage operation direction. It is characterized in that a feedforward input is provided so as to rotate the table.

[0014]

According to the above configuration, it is possible to suppress the shaking of the vibration isolation table due to the movement of the center of gravity of the entire vibration isolation table accompanying the movement of the mounted device, that is, to realize the correction of the center of gravity of the vibration isolation table. Japanese Patent Application Laid-Open No. Hei 9-134876 describes an apparatus for compensating for a change in the center of gravity due to the movement of the stage by feeding the current position of the stage to the anti-vibration table control system. However, the biggest difference from the vibration damping device according to the first aspect of the present invention is that the value to be fed forward is the target value in the present invention, but is the current value (or measured value) in the above publication. On the point. The target value can be fed forward earlier than the current value, and vibration can be more effectively prevented.

In recent years, the control system of the stage and the vibration isolation table is often realized as a digital control system using a microcomputer capable of high-speed operation. In addition, since the number of controlled objects is large, the control system is controlled using a plurality of CPUs. Make up. When the stage control system and the anti-vibration table control system are configured by different CPUs, a means for transmitting the target position and speed (or the current position and speed) of the stage from the stage control system to the anti-vibration table control system is required. is there. Although the current position and speed can be obtained directly from the sensor, it is necessary to provide an information transmission path (such as a cable) with the sensor.

A second object of the present invention is to provide a vibration damping apparatus which can improve the vibration damping performance without providing a direct information exchange means between the stage control system and the vibration damping table control system. Aim.

In order to achieve the second object, a second aspect of the present invention is characterized in that stage target value generating means for generating the stage target value is provided independently of the stage device. In the stage target value generating means, the stage target value is generated based on information from a sequence controller which inputs a stage position command value and a stage movement start command to the stage controller, and the stage target value is fed forward to the anti-vibration table controller. input. For example, the stage target position is generated from the stage position at the start of the stage movement and the stage position command value.

In a preferred embodiment of the second aspect, the stage target value generating means generates a stage target position, a stage target speed and / or a stage target acceleration. Further, the stage target speed and / or the stage target acceleration are transmitted to the anti-vibration table controller so as to predict and correct the inclination of the anti-vibration table caused by the movement of the position of the center of gravity during the stage movement from the target stage position. The actuator is driven by feed forward.

According to the anti-vibration apparatus according to the second aspect of the present invention, the stage moves to the target position generated by the stage target value generation means of the stage controller, and the anti-vibration table is controlled by the anti-vibration table controller. By calculating the tilt of the anti-vibration table accompanying the movement of the center of gravity from the target position generated by the stage target value generating means, and driving the actuator to correct the tilt, the vibration damping performance can be improved.

[0020]

Embodiments of the present invention will be described below with reference to the drawings. First Embodiment FIG. 1 shows a configuration of an air spring type vibration damping device according to a first embodiment of the present invention. The same elements as those in FIG. 5 are given the same numbers. In FIG. 1, 35 is a stage target speed generator for generating a target speed of the stage, 36 is an integrator, and 37 is a filter having a predetermined appropriate gain and time constant.

FIG. 2 shows the target speed generated by the target speed generator 35 as time on the horizontal axis. This speed pattern is well known as a trapezoidal speed pattern. FIG. 2 also shows a target acceleration, which is a differential value of the target speed, and a target position, which is an integral value of the target speed. The target speed can be described as a function of the elapsed time from the movement start time, or can be generated by integrating the target acceleration. In the present embodiment, the latter is adopted. The target speed is converted to a target position through an integrator 36 and input to a stage controller, which is a position control system of the stage 16.
Further, the target speed is passed through a filter 37 to the anti-vibration table 15.
Is fed-forward input to a control system for rotational displacement in the pitching direction with respect to the operation direction of the stage 16 through the center of gravity of the stage 16.

In the equilibrium state of the air spring, the transfer function from the input current I of the servo valve to the air spring pressure P is
Flow gain of the servo valve to G _q, k the specific heat ratio of air,
The air spring pressure in the P ₀ equilibrium state, V ₀ is the air spring volume in the equilibrium state, and s is the Laplace operator,

[0023]

(Equation 1) It is generally known that the integral characteristic can be approximated. Therefore, the target speed fed forward to the rotational displacement control system of the vibration isolation table 15 is integrated by the integration characteristic of the air spring, so that the feed speed of the target speed reduces the rotational torque proportional to the target position of the stage 16. This is equivalent to giving to the vibration isolation table 15. By the feedforward input of the target speed, the rotational moment generated by the movement of the stage 16 can be canceled, and the vibration of the vibration isolation table 15 can be effectively suppressed. Further, in the air spring type vibration damping device of the present embodiment,
The anti-vibration table controller, which is the position control system of the anti-vibration table, is separated in the vertical direction and the rotation direction, and the feed forward input of the target speed is performed only in the position control system in the rotation direction. It has no adverse effect on vertical movement that is not possible.

Second Embodiment In the first embodiment, the target speed is fed forward to the anti-vibration table rotational displacement control system, but the drive input of the stage 16 is fed forward instead of the target speed. Can also. FIG. 3 shows the configuration of the air spring type vibration damping device at that time. PID which is a drive input of stage 16
The output of the compensator 21 is fed forward to the rotational displacement control system of the vibration isolation table through the integrator 38 and the filter 37. By adopting this configuration, similarly to the first embodiment, the rotational moment generated by the movement of the stage 16 can be canceled, and the vibration of the vibration isolation table 15 can be effectively suppressed.

Third Embodiment FIG. 4 shows the configuration of a vibration damping device according to a third embodiment of the present invention. This anti-vibration device is for supporting a stage in a semiconductor exposure apparatus for anti-vibration. The same elements as those in FIG. 1 are given the same numbers. In FIG. 4, reference numeral 39 denotes a second stage target speed generator. While the apparatus shown in FIG. 1 feeds forward the stage target speed from the stage target speed generator 35 for the stage control system to the anti-vibration table control system,
In the apparatus of FIG. 4, a second stage target speed generator dedicated to feedforward is provided separately from the first stage target speed generator 35 for the stage control system. This eliminates the need to provide a direct information exchange means between the stage control system and the vibration isolation table control system. An information transmitting means for transmitting a stage position command value and a stage movement start command from the sequence controller 40 to the anti-vibration table control system is necessary. In many cases, information such as a shaking table target position command is exchanged. In such a case, no additional information transmission means is required, and the configuration can be simplified.

Next, the operation of the vibration isolator of FIG. 4 will be described.
The sequence controller 40 simultaneously transmits the next target position of the stage 16 and a stage movement start command to the first stage target speed generator 35 and the second stage target speed generator 39. When the stage movement start command comes, the first
Stage target speed generator 35 and second stage target speed generator 39 send the same stage target speed to integrator 36 and filter 37 at the same timing, respectively. The output of the integrator 36 is given to the stage control system as a stage target position, and the output of the filter 37 is
5 is fed-forward input to a control system for rotational displacement in the pitching direction with respect to the operation direction of the stage 16 through the center of gravity of the stage 16.

By the feedforward input of the stage target speed, as described in the first embodiment,
The rotational moment generated by the movement of the stage 16 can be canceled, and the vibration of the vibration isolation table 15 can be effectively suppressed. Also in the air spring type vibration damping device of this embodiment, the vibration damping table controller, which is a position control system of the vibration damping table, is separated in the vertical direction and the rotation direction, and the feedforward input of the target speed is performed in the rotation direction. Is performed only on the position control system, and therefore, there is no adverse effect on the vertical operation in which the feedforward input is not performed. Further, a second stage for generating a stage target position based on a command from the sequence controller 40 or the like exclusively for feedforward input is provided.
By providing the stage target position generator, the information exchange means between the stage position control system and the anti-vibration table control system becomes unnecessary, and it is highly possible that the configuration can be simplified.

Modifications of Embodiments The present invention is not limited to the above-described embodiments, but can be implemented with appropriate modifications. For example, in the above-described embodiment, the number of the support legs for supporting the vibration isolation table is two in the vertical direction. However, the number may be three or more. When there are three supporting legs in the vertical direction, the position control system of the vibration isolation table can be expressed in a rectangular coordinate system as a translation control system in the z-axis direction, a rotation control system around the x-axis, and a rotation control system around the y-axis. The following three control systems are configured.
In this case, the displacement decomposer, the acceleration decomposer, and the thrust distributor each perform a 3 × 3 matrix calculation. When the operation direction of the stage is the y-axis direction, the target speed of the stage is fed forward to the rotation control system around the x-axis of the vibration isolation table.

The operation direction of the stage may be such that it operates on a two-dimensional plane like the XY stage. When there are three support legs in the vertical direction, the x-axis target speed of the XY stage is set to the rotation control system around the y-axis of the vibration isolator, and the y-axis target speed of the XY stage is set to about the x-axis of the vibration isolator. Feedforward input is made to each of the rotation control systems. Thus, the rotational moment due to the movement of the center of gravity accompanying the movement of the XY stage can be canceled.

In the above-described embodiment, only the air spring is used as the actuator. However, a voice coil motor is used together to feed forward the target stage position to the motor control system to correct the tilt due to the movement of the center of gravity accompanying the stage movement. be able to. Furthermore, the stage target acceleration can be fed forward to the motor control system to cancel the stage driving reaction force. In this case, the stage target position and the stage target acceleration can be generated by connecting an integrator and a differentiator to the second stage target speed generator 39, respectively.

Further, the stage target speed generator 3 shown in FIG.
The stage target position generator 20 shown in FIG. 3 or 5 may be used instead of the integrator 36 and the integrator 36.

[0032]

As described above, according to the present invention, the target speed of the stage or the value obtained by integrating the drive signal of the stage is input to the anti-vibration table controller in a feed-forward manner, thereby removing the stage generated by the movement of the stage. Shaking of the shaking table can be effectively suppressed. That is, the center of gravity of the vibration isolation table can be corrected. In addition, by providing the target value generation means of the stage control system also in the anti-vibration table control system, there is no need to provide a means for exchanging data between the stage control system and the anti-vibration table control system. The tilt due to the movement of the center of gravity and the stage driving reaction force can be compensated, and the vibration damping performance of the vibration damping table can be improved.

[Brief description of the drawings]

FIG. 1 is a diagram showing a configuration of an air spring type vibration damping device according to one embodiment of the present invention.

FIG. 2 is a diagram showing a target value of a stage.

FIG. 3 is a diagram showing a configuration of an air spring type vibration damping device according to another embodiment of the present invention.

FIG. 4 is a view showing a configuration of an air spring type vibration damping device according to still another embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a conventional air spring type vibration damping device.

[Explanation of symbols]

1, 8: air spring type support leg, 16: stage, 20: stage target position generator, 25: displacement decomposer, 30: acceleration decomposer, 31: thrust distributor, 34: anti-vibration table target position setter, 35, 39: Stage target speed generator, 36, 3
8: integrator, 37: filter, 40: sequence controller.

──────────────────────────────────────────────────の Continued on the front page (51) Int.Cl. ⁶ Identification code FI H01L 21/027 H01L 21/30 503F

Claims (10)

[Claims] An anti-vibration table, an air spring that supports and drives the anti-vibration table, a servo valve that adjusts the pressure of the air spring, a displacement sensor that detects a displacement of the anti-vibration table, and the displacement A vibration isolation table controller that generates a drive signal for the servo valve so that the vibration isolation table maintains a predetermined posture at a predetermined position based on an output of a sensor, and is mounted on the vibration isolation table. A stage device having a stage, a position sensor for detecting a position of the stage, and a stage controller for controlling the stage to maintain a predetermined position based on an output of the position sensor, supports the stage in vibration isolation. In the vibration damping device, a target speed of the stage is input to the vibration damping table controller in a feed-forward manner. 2. A stage target for generating said target speed based on information from a sequence controller for inputting a stage position command value and a stage movement start command to said stage controller and feed-forward inputting said target speed to said anti-vibration table controller. 2. The vibration isolator according to claim 1, wherein a speed generating unit is provided independently of the stage device. 3. An anti-vibration table, an air spring for supporting and driving the anti-vibration table, a servo valve for adjusting the pressure of the air spring, a displacement sensor for detecting a displacement of the anti-vibration table, and the displacement A vibration isolation table controller that generates a drive signal for the servo valve so that the vibration isolation table maintains a predetermined posture at a predetermined position based on an output of a sensor, and is mounted on the vibration isolation table. A stage, a stage actuator for driving the stage, a position sensor for detecting the position of the stage, and a drive signal for the stage actuator generated based on an output of the position sensor so that the stage maintains a predetermined position. A stage controller having a stage controller for supporting the stage in vibration isolation, wherein a value obtained by integrating a drive signal of the stage actuator is input to the vibration isolation table controller. Anti-vibration apparatus characterized by feedforward input. 4. The feedforward input is provided so that a value for rotating the vibration isolation table in a pitching direction with respect to an operation direction of the stage is added to a drive signal of the servo valve. The vibration isolator according to any one of claims 1 to 3. 5. An anti-vibration table, an air spring that supports the anti-vibration table, an actuator that drives the anti-vibration table, a displacement sensor that detects a displacement of the anti-vibration table, and an output of the displacement sensor. A vibration isolation table controller that generates a drive signal of the actuator so that the vibration isolation table maintains a predetermined posture based on the vibration isolation table,
A stage mounted on the vibration isolation table, a position sensor for detecting a position of the stage, and a stage controller for controlling the stage to maintain a predetermined position based on an output of the position sensor. An anti-vibration device for supporting an anti-vibration stage of a stage device, wherein a target value for driving the stage is input to the anti-vibration table controller in a feed-forward manner. 6. A stage target for generating said target value based on information from a sequence controller for inputting a stage position command value and a stage movement start command to said stage controller and feed-forward inputting said target value to said anti-vibration table controller. 6. The vibration isolation device according to claim 5, wherein a value generation unit is provided independently of the stage device. 7. The anti-vibration apparatus according to claim 5, wherein the stage target value generation means generates a stage target position, a stage target speed, and / or a stage target acceleration. 8. The actuator according to claim 7, wherein the actuator is driven so as to predict and correct the inclination of the anti-vibration table caused by the movement of the position of the center of gravity during the movement of the stage from the stage target position. Anti-vibration device. 9. The anti-vibration apparatus according to claim 7, wherein the target stage speed and / or the target stage acceleration is fed forward to the anti-vibration table controller. 10. The vibration isolator according to claim 9, wherein said actuator is a voice coil motor.