JPH11150062A - Vibration isolator, aligner, and method for canceling vibration of vibration canceling base - Google Patents

Abstract

PROBLEM TO BE SOLVED: To sufficiently secure a low frequency gain of a speed control loop, by simulating the shifting of the frequency in rigid body made of a body falsely to low frequency. SOLUTION: When a vibration canceling base 6 is vibrated by the reaction by the acceleration and deceleration during shifting of stages 20 and 27, the displacement of this vibration canceling base 6 is measured by a displacement sensors (10A-10C), and a vibration compensation system feeds forward and inputs the thrust command value being decided according to the output of the displacement sensor or the acceleration sensors (5A-5C) and the elastic modulus and damping coefficient of vibration canceling pads (8A-8D) into a vibration control system. The vibration control system drives and controls each actuator (7A-7C, and 32A-32C) so as to suppress the vibration of the vibration canceling base, based on the output of the displacement sensor and the vibration sensor and the thrust command value being fed forward and inputted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an anti-vibration apparatus, an exposure apparatus and an anti-vibration method for an anti-vibration table, and more particularly, to driving an anti-vibration table by an actuator so as to cancel the vibration of the anti-vibration table. The present invention relates to a so-called active type anti-vibration apparatus, an exposure apparatus including the anti-vibration apparatus, and a method of removing an anti-vibration table.

[0002]

2. Description of the Related Art Step-and-repeat or step-and-scan reduction projection type exposure apparatuses,
That is, with the increase in precision of precision equipment such as a so-called stepper, it has become necessary to insulate micro-vibrations acting on the surface plate (vibration isolation table) from the installation floor at the micro G level. Various types of vibration dampers, such as mechanical dampers or pneumatic dampers in which a compression coil spring is placed in a diping solution, are used as vibration damping pads for supporting the vibration damping table of the vibration damping device. The vibration damping pads themselves have a certain degree of centering function. Have. In particular, an air spring vibration isolator equipped with a pneumatic damper can set a small spring constant,
Since it insulates vibrations of about 10 Hz or more, it is widely used for supporting precision equipment. Recently, active vibration isolators have been proposed to overcome the limitations of conventional passive vibration isolators. This is a vibration isolation device that detects vibration of the vibration isolation table with a sensor and drives the actuator based on the output of the sensor to perform vibration control.
It is possible to provide an ideal vibration isolation effect without a resonance peak in the low frequency control band.

[0003]

In particular, in a scanning exposure apparatus such as a step-and-scan type reduction projection exposure apparatus or the like, an exposure apparatus in which a reaction force during acceleration / deceleration of a stage, particularly a reticle stage, includes a surface plate. In order to offset the body (hereinafter also referred to as the "body"), a counterforce of the same size as the counterforce is applied to the body in the opposite direction to the force exerted on the body by the reaction force of the stage.
However, the counterforce actually has a time delay slightly smaller than the stage reaction force, and the delay of the counterforce may vibrate the body. This vibrating force results in residual vibration of the body, which causes the accuracy of the exposure apparatus to deteriorate (for example, the printing accuracy deteriorates).

[0004] To avoid this, an accelerometer, for example, is mounted on the body as a vibration detection sensor, and a servo system (speed control system) is assembled to positively control the shaking of the body.

However, in the case of an exposure apparatus in which a coil spring mount is used as an anti-vibration pad and the body is supported by the coil spring mount, it is difficult for a conventional servo control system to have a sufficient gain in a control band. Therefore, there is an inconvenience that sufficient damping performance cannot be obtained even though the servo system is configured. That is, since the coil spring mount has a large (hard) spring constant (elastic coefficient), the frequency of the rigid body mode of the body is higher than when an air mount (air spring) is mounted, and the servo system gain is sufficiently increased. Then, the body may be vibrated at this frequency, and the printing accuracy or the like may be deteriorated. As a result, the gain in the speed control band cannot be sufficiently secured.

Further, in the case of an exposure apparatus in which an air mount is used as an anti-vibration pad and the body is supported by the air mount,
Although the above inconvenience does not cause much problem, the air mount is more expensive than the coil spring mount, and causes an increase in cost.

The present invention has been made under such circumstances, and a first object of the present invention is to simulately shift the frequency of a rigid mode of a body to a low frequency and sufficiently increase the low frequency gain of a speed control loop. An object of the present invention is to provide an anti-vibration device which can be ensured in a vehicle.

It is a second object of the present invention to provide a vibration damping device capable of effectively damping residual vibration due to damage to the counterforce.

A third object of the present invention is to provide an exposure apparatus capable of performing high-precision exposure by effectively suppressing vibration even when mechanical resonance of the body occurs in a high frequency range. It is in.

A fourth object of the present invention is to effectively suppress vibration even when mechanical vibration of the vibration isolation table occurs in a high frequency range without vibrating the mechanical resonance mode. An object of the present invention is to provide a vibration isolation method for a vibration isolation table.

[0011]

According to a first aspect of the present invention, there is provided an anti-vibration apparatus comprising at least three anti-vibration pads (8A to 8A).
8D); a vibration isolation table (24) held horizontally; at least one stage (20, 27) moving on the vibration isolation table (24); At least three actuators (7A-
7D) including a plurality of actuators (7A to 7D, 32
A to 32C) and one or more sensors (10A to 10C, 5A to 5C) for detecting displacement or vibration of the vibration isolation table.
A vibration control system (11) that drives and controls each of the actuators to suppress vibration of the vibration isolation table based on the output of the sensor; and suppresses vibration of the vibration isolation table that occurs when the stage is accelerated or decelerated. In order to generate such a thrust in the actuator, a thrust command value determined according to the output of the sensor and at least one of the elastic coefficient and the damping coefficient of the vibration isolation pad is feedforward input to the vibration control system. A vibration compensation system (60).

According to this, when the vibration damping table vibrates due to the reaction force due to acceleration and deceleration during the movement of the stage, the vibration or displacement of the vibration damping table is measured by the sensor. A thrust command value determined according to at least one of the elastic coefficient and the damping coefficient of the vibration pad is fed forward to the vibration control system. The vibration control system drives and controls each actuator based on the output of the sensor and the thrust command value input in a feedforward manner so as to suppress the vibration of the vibration isolation table. As a result, the frequency of the rigid body mode of the body including the anti-vibration table is shifted to a low frequency range (that is, the poles of the system are shifted to the low frequency range), and the high frequency mechanical resonance mode of the body is not excited. In addition, a low-frequency gain of the speed control loop constituting the vibration control system can be sufficiently ensured.

In this case, a command value of a thrust (counter force) in a direction opposite to the acceleration immediately after the start of movement and immediately before the stop of the stage is fed-forward input to the vibration control system. A scan counter (66) may be further provided. In such a case, the command value of the thrust (counterforce) in the direction opposite to the acceleration immediately after the start and immediately before the stop of the movement of the stage by the scan counter is fed forward to the vibration control system. The drive of the actuator is controlled so as to suppress the vibration generated on the vibration isolation table immediately after the start and immediately before the stop. Further, even if the vibration isolation table is vibrated due to the delay of the counter force by the scan counter, the residual vibration is effectively controlled by the actuator control based on the thrust command value that is fed forward from the vibration compensation system to the vibration control system. Can be shaken.

In the vibration isolator according to the first or second aspect of the present invention, as in the third aspect of the present invention, the vibration isolating pad may be a mechanical damper having a coil spring. Alternatively, as in the invention described in claim 4,
The vibration isolation pad may be a pneumatic damper provided with an air spring. In the former case, the frequency of the rigid body mode of the body including the vibration isolation table is shifted to a low frequency region by feedforward input of the command value from the vibration compensation system, and as a result, a mechanical damper is used. Nevertheless, a high level of vibration damping effect similar to the use of a pneumatic damper can be obtained, and in the latter case, a device for controlling an actuator using a correction command value that is a function of the position of the stage ( A so-called offset load counter is not required.

According to a fifth aspect of the present invention, there is provided an exposure apparatus comprising:
An exposure apparatus for transferring a pattern formed on a mask onto a photosensitive substrate on a substrate stage via a projection optical system, wherein the vibration isolation apparatus according to any one of claims 1 to 4 is provided on an exposure apparatus main body. It is provided as a vibration isolation device.

According to this, by the action of the vibration isolator according to any one of claims 1 to 4, vibration can be effectively suppressed even when mechanical resonance of the body occurs in a high frequency range. As a result, highly accurate exposure can be performed.

According to a sixth aspect of the present invention, there is provided an anti-vibration pad (8
A-8D) and actuators (7A-7D, 32A-3)
2C) and the stage (20, 27) moves on the upper surface thereof, and the stage (20, 27) moves on the basis of a sensor output for detecting displacement or vibration of the table. Providing a thrust command value determined according to at least one of an elastic coefficient and a damping coefficient of the vibration isolating pad to the actuator so as to suppress shaking of the vibration isolating table generated during acceleration and deceleration of the stage. I do.

According to this, when the vibration damping table vibrates due to the reaction force due to acceleration and deceleration during the movement of the stage, the vibration is generated when the stage is accelerated or decelerated based on the sensor output for detecting the displacement or vibration of the vibration damping table. A thrust command value determined according to at least one of the elastic coefficient and the damping coefficient of the vibration isolation pad is given to the actuator so as to suppress the vibration of the vibration isolation table. The actuator is driven based on the thrust command value, and the vibration isolation table is isolated. As a result, the frequency of the rigid body mode of the body including the vibration isolation table is shifted to a low frequency range (ie, the pole of the system is shifted to the low frequency area), and the high frequency mechanical resonance mode of the vibration isolation table is excited. Without this, the vibration damping table is effectively damped.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic perspective view of a step-and-scan type exposure apparatus 100 according to one embodiment. In FIG. 1, a base frame (frame caster) 2 having a rectangular plate shape is installed on a floor as an installation surface, and mounting portions 4A to 4D are mounted on the base frame 2.
(However, in FIG. 1, the mount 4D on the far side of the drawing is not shown), and a main frame 24 as an anti-vibration table is supported on these mounts 4A to 4D. The main frame 24 includes an upper plate and a wafer stage base plate (surface plate) 6 integrally fixed below the upper plate via four columnar members 25. Here, as will be described later, since the projection optical system (Projection Lens) PL is used in the present embodiment, the Z axis is taken in parallel with the optical axis of the projection optical system PL, and the wafer is set in a plane orthogonal to the Z axis. The Y axis is set in the depth direction of the stage base plate 6, and the X axis is set in a direction orthogonal to the Y axis. The directions of rotation around the respective axes are defined as Zθ, Yθ, and Xθ directions. In the following description, directions indicated by arrows indicating X, Y, and Z axes in FIG.
The + Z direction and the opposite direction are used separately from the -X, -Y, and -Z directions.

The mounts 4A to 4D are arranged near four vertexes on the rectangular bottom surface of the wafer stage base plate 6, respectively. Each mounting part 4 (4A-4D)
Are composed of Z actuators 7 (7A to 7D) and vibration isolation pads 8 (8A to 8D), respectively. In the present embodiment, a mechanical damper in which a compression coil spring is put in a damping liquid is used as the vibration isolation pads 8A to 8D. Of course, a pneumatic damper may be used as the vibration isolation pad.

The Z actuators 7A to 7D (7D not shown) are a stator (not shown) fixed on the base frame 2 and a mover (not shown) fixed to the bottom of the vibration isolation pads 8A to 8D. The control device 11 (FIG. 1)
(Not shown, see FIG. 2). The urging force in the Z direction from the base frame 2 to the bottom surfaces of the vibration isolation pads 8A to 8D or the suction force from the bottom surfaces of the vibration isolation pads 8A to 8D toward the base frame 2 in response to an instruction from the base frame 2. Occurs.

At the + Y direction end of the upper surface of the main frame 24 integrated with the wafer stage base plate 6,
The X-direction end portion, XZ acceleration sensor 5A as a sensor for a Z accelerometer 5Z ₁ for detecting the X acceleration sensor 5X and Z-direction acceleration detecting X-direction acceleration of the main frame 24 are integrated (vibration sensor) Is attached. Further, the end portion of the + X direction in the -Y direction end of the main frame 24 the upper surface, and a Z acceleration sensor 5Z ₂ for detecting the Y acceleration sensor 5Y ₁ and Z-direction acceleration detecting the Y-direction acceleration of the main frame 24 A YZ acceleration sensor 5B as an integrated sensor (vibration sensor) is attached. In FIG. 1, the projection optical system PL is provided at the end in the + X direction at the end in the −Y direction on the upper surface of the main frame 24.
Although it is shown because hidden behind the inverter 12 for holding is omitted, together with the Z acceleration sensor 5Z ₃ for detecting the Y acceleration sensor 5Y ₂ and Z-direction acceleration detecting the Y-direction acceleration of the main frame 24 is A YZ acceleration sensor 5C as a sensor (vibration sensor) is provided. The acceleration sensor 5A~5C (5Z _1, 5Z _{2,
5Z 3, 5Y 1, 5Y 2} , 5X) as is, for example, a semiconductor type acceleration sensor is used. The outputs of these acceleration sensors 5A to 5C are also controlled by the controller 11 (not shown in FIG. 1,
(See FIG. 2).

A pair of horizontal actuator support frames 9A and 9B made of portal casting are provided upright at both ends in the X direction on the upper surface of the base frame 2. + Y on the upper surface of the horizontal actuator support frame 9B on the −X direction side
At the end in the direction, an X displacement sensor 10X for detecting the displacement of the main frame 24 in the X direction and a Z displacement for detecting the displacement in the Z direction are provided.
XZ displacement sensor 10A as a sensor and displacement sensor 10Z ₁ is formed by integrally is fixed. Although not shown in FIG. 1 at the end in the −Y direction on the upper surface of the horizontal actuator support frame 9B because it is hidden behind the main frame, a Y for detecting the displacement of the main frame 24 in the Y direction is omitted. YZ displacement sensor 10B as a sensor and the Z displacement sensor 10Z ₂ for detecting the displacement of the displacement sensor 10Y ₁ and Z direction, which are integrally is fixed. A main frame 2 is provided at the end in the −Y direction on the upper surface of the horizontal actuator support frame 9A on the + X direction side.
4 of detecting the Y-direction displacement Y displacement sensor 10Y ₂ and Z
YZ displacement sensor 10C as a sensor composed of integrated and the Z displacement sensor 10Z ₃ to detect the direction of displacement is fixed.

The displacement sensors 10A to 10C (10
_{Z 1, 10Z 2, 10Z 3} , 10Y 1, 10Y 2, 10
As X), for example, an eddy current displacement sensor is used. According to this eddy current displacement sensor, an AC voltage is applied to a coil wound on an insulator in advance, and when the sensor approaches an object to be measured made of a conductive material (conductive material), the AC magnetic field generated by the coil causes the AC magnetic field to be applied to the conductive material. An eddy current is generated, and the magnetic field generated by the eddy current is in the opposite direction to the magnetic field created by the coil current, and these two magnetic fields overlap to affect the output of the coil, and the current flowing through the coil The intensity and phase change. This change becomes larger as the object is closer to the coil and becomes smaller as the object is farther from the coil. Therefore, by extracting an electric signal from the coil, the position and displacement of the object can be known. These displacement sensors 10
The outputs of A to 10C are also controlled by the control device 11 (not shown in FIG. 1,
(See FIG. 2). In addition, as a displacement sensor, a capacitance-type non-contact displacement that detects the distance between the sensor and the measurement object in a non-contact manner by utilizing that the capacitance is inversely proportional to the distance between the electrode of the sensor and the measurement object A sensor may be used. If the configuration is such that the influence of the background light can be prevented, a PSD (semiconductor optical position detector) can be used as the displacement sensor.

An XY stage 20 driven in a two-dimensional XY direction by a driving system such as a linear motor (not shown) is mounted on the wafer stage base plate 6. Further, a Z leveling stage is provided on the XY stage 20,
θ stage (both not shown) and wafer holder 21
A wafer W as a photosensitive substrate is suction-held through the substrate. An invar 12 holding the projection optical system PL is fixed above the wafer stage base plate 6 and at the center of the upper plate of the main frame 24 integrated therewith.
A reticle stage 27 for holding a reticle R as a mask is mounted on the upper portion of the invar 12. The reticle stage 27 can be driven at a predetermined stroke in the X direction by a drive system 28 composed of a linear motor, and can be driven in a small amount in the Y direction.

A support frame 26 is implanted above the main frame 24 so as to surround the invar 12 and the reticle stage 27.
Supports an illumination optical system (not shown).

XY stage 20 and reticle stage 2
The position of 7 is measured by laser interferometers (not shown), and the measured values of these interferometers are input to a main controller (not shown). The Z leveling stage is configured so that the drive in the Z-axis direction and the tilt with respect to the Z-axis can be adjusted,
The θ stage is configured to be capable of minute rotation about the Z axis. Therefore, the wafer W can be three-dimensionally positioned by the XY stage 20, the Z leveling stage, and the θ stage.

Further, a main controller (not shown) performs relative positioning (alignment) of the reticle R and the wafer W and performs auto-focusing by a focus detection system (not shown), and under the illumination light for exposure from the illumination optical system. , The pattern of reticle R to wafer W through projection optical system PL.
Are sequentially transferred to each shot area. In this embodiment, when exposing each shot area, the XY stage 20 and the reticle stage 27 are relatively scanned by the main controller at a predetermined speed ratio along the X-axis direction (scanning direction) via respective drive systems. You.

On the upper part of the horizontal actuator support frame 9B, a stator 34 of the Y actuator 32B is provided.
B is fixed. Opposite to this, Y is provided on the upper surface of the main frame 24 at the end in the + Y direction and at the corner of the end in the -X direction.
The mover 33B of the actuator 32B is fixed. The Y actuator 32B applies a biasing force in the Y direction from the horizontal actuator support frame 9B to the main frame 24 or a suction force in the Y direction from the main frame 24 to the horizontal actuator support frame 9B in response to an instruction from the control device 11. Occur.

Similarly, the stator 34C of the Y actuator 32C is fixed on the upper part of the horizontal actuator support frame 9A.
The mover 33C of the Y actuator 32C is fixed to the upper surface at the + Y direction end and at the corner at the + X direction end. The Y actuator 32C moves the horizontal actuator support frame 9 in response to an instruction from the control device 11.
A generates a biasing force in the Y direction from A to the main frame 24 or a suction force in the Y direction from the main frame 24 to the horizontal actuator support frame 9A.

The stator 3 of the X actuator 32A is mounted on the upper part of the horizontal actuator support frame 9A.
4A is fixed, and a mover 33A of the X actuator 32A is fixed to a central portion of the upper surface of the main frame 24 in the Y direction and an end portion in the + X direction opposite thereto.
The X actuator 32A applies an urging force in the X direction from the horizontal actuator support frame 9A to the side surface of the main frame 24 or a suction force from the side surface of the main frame 24 to the horizontal actuator support frame 9A in response to an instruction from the control device 11. Occurs.

In this embodiment, a body (exposure apparatus main body) 40 (main body of the exposure apparatus) is formed by the wafer stage base plate 6, the XY stage 20, the wafer holder 21, the main frame 24, the projection optical system PL, the invar 12, the support frame 26, the reticle stage 27, and the like. (See FIG. 2).

Next, a control system 200 for the actuators 7A to 7D and 32A to 32C for removing the vibration of the body 40.
Will be described with reference to the control block diagram of FIG. In FIG. 2, for simplicity of description, only the control system in the X direction out of the six degrees of freedom of X, Y, Z, Xθ, Yθ, and Zθ is shown. Other 5 similar to the X direction shown in FIG.
Needless to say, a control system in the direction of freedom is provided.

The control device 11 includes displacement sensors 10A to 10A.
_{C (10Z 1, 10Z 2,} 10Z 3, 10Y 1, 10Y
_2, 10X) and an acceleration sensor 5A~5C (5Z _1, 5
_{Z 2, 5Z 3, 5Y 1} , 5Y 2, the actuator 7 so as to suppress the vibration of the body 40 on the basis of the output of 5X)
A, 7B, 7C, 7D, 32A, 32B, 32C, a vibration control system for driving and controlling the XY stage 20 and the reticle stage 27 during acceleration / deceleration, for example, X for scanning exposure.
Body 4 including wafer stage base plate 6 generated during scanning of Y stage 20 and reticle stage 27
A thrust that suppresses the swing of the actuator 7
A, 7B, 7C, 7D, 32A, 32B, and 32C, acceleration sensors 5A to 5C (5Z ₁ , 5
_{Z 2, 5Z 3, 5Y 1} , 5Y 2, the output of 5X) (or displacement sensor _{10A~10C (10Z 1, 10Z 2,} 10Z
₃ , 10Y ₁ , 10Y ₂ , 10X)) and a vibration compensation system 60 for feed-forward inputting a thrust command value determined according to the elastic coefficients and damping coefficients of the vibration isolation pads 9A to 9D to the vibration control system. .

Here, the control system in the X direction will be described with reference to FIG. The vibration control system receives a target value x ₀ and a displacement x of the body 40 in the X direction, and calculates a position deviation Δx = x ₀ −x, which is a difference between the two, and an output from the subtracter 46. And a integrator 50 that integrates the X-direction acceleration x ″ of the body 40 and converts the X-direction acceleration x ″ of the body 40 into an X-direction speed x ′ of the body 40.
And the output of the position controller XPI to the speed command value x ₀ '.
And a subtraction for calculating the speed deviation in the X direction (Δx ′ = x ₀ ′ −x ′) by subtracting the output x ′ of the integrator 50 from the converted speed command value x ₀ ′. Vessel 5
4 and a speed controller VXPI comprising a PI controller performing a control operation using the speed deviation Δx ′ as an operation signal.
And a speed-thrust conversion gain 58 for converting the speed control amount in the X direction calculated by the controller VXPI into a thrust to be generated by the X actuator 32A. Here, as the displacement x in the X direction of the body 40, which is fed back to the subtractor 46, the displacement detected by the displacement sensor 10X is input. In FIG. The integrator 50 and the integrator 51 calculate the acceleration x ″ of the body 40 detected by the acceleration sensor 5X.
Shown as times integrated.

That is, the vibration control system according to the present embodiment includes an acceleration sensor as an inner loop inside a position control loop including a displacement sensor, a position controller, and the like.
The multi-loop control system has a speed control loop including an integrator, a speed controller, and the like.

The vibration compensation system 60 includes a conversion gain c ′ for converting an X-direction speed x ′ obtained by integrating the acceleration x ″ of the body 40 by the integrator 50 into a thrust command value, and an X-direction speed x ′. , A gain k ′ for converting the displacement x obtained by the integrator 64 into a thrust, a sum of outputs of the gain c ′ and the gain k ′, ｛c ′ (dx / dt) +
k′x 器 is calculated, and an adder 68 that feeds the sum to a vibrating control system via an adder 62 provided on the output side of the gain 58 is provided.

The portion indicated by reference numeral 8 included in the control system of FIG. 2 is a vibration system model (mechanical model) that schematically represents the vibration isolation pads 8A to 8D. The output {c (dx / dt) + kx} from 8 is fed back to the adder 62.

Therefore, the thrust from the gain 58 is expressed as f (t)
Then, the thrust F which is the output of the adder 62 is expressed by the following equation. However, here, the output of the scan counter described later is ignored.

F = f (t) + {c ′ (dx / dt) + k ′
x｝ − {c (dx / dt) + kx} However, due to the thrust F, the body 40 having the mass m becomes X
Since the directional acceleration d ² x / dt ² is generated, the thrust F can be expressed by the following equation.

F = m · (d ² x / dt ² ) = ma Therefore, from the above two equations, it is possible to obtain the following equation: ma · f (t) + {c ′ (dx / dt) + k′x} −
{C (dx / dt) + kx} Therefore, assuming that the second term on the right-hand side of the above equation is the third term on the right-hand side, then: m · a = m · (d ² x / dt ² ) = f (t) Thus, a control system similar to the case where there is no repulsive force, that is, when there is no vibration isolation pad can be configured. Therefore, in the present embodiment, the gains c ′ and k ′ are determined so as to substantially match the damping coefficients and the spring constants (elastic coefficients) of the vibration isolation pads 8A to 8D, and the thrust command value {c ′ (dx / D
t) + k'x} is feed-forward input to the oscillating control system.

The control system 200 for the actuator of the exposure apparatus 100 has other five-degree-of-freedom directions (Y, Z, Xθ,
Yθ, Zθ). In the control system 200, the six displacement sensors 10Z ₁ , 10Z ₂ , 10Z ₃ , 1 are located at the position of point A in FIG.
A coordinate conversion unit for converting the outputs of 0Y ₁ , 10Y ₂ , and 10X into displacements of the center of gravity of the body 40 in the directions of six degrees of freedom is provided;
At the position of point B in FIG. 2, command values from the speed controller in the directions of six degrees of freedom are assigned to the seven actuators 7A, 7B, 7
C, 7D, 32A, 32B, and 32C, a decoupling calculation unit that converts the speed into a speed corresponding to the command value of the thrust to be generated is provided. Further, at the position of point C in FIG. sensor _{5Z 1, 5Z 2, 5Z 3} , 5Y 1, 5Y
A coordinate conversion unit is provided for converting the output of ₂ , 5X into acceleration in the direction of six degrees of freedom. That is, in the above description, it has been described that the outputs of the displacement sensor 10X and the acceleration sensor 5X are directly input to the subtractor 46 and the integrator 50.
Actually, the displacement and acceleration of the center of gravity of the body 40 are input to the subtractor 46 and the integrator 50.

Further, in this embodiment, the output of the scan counter 66 is fed forward to the vibration control system via the adder 62 provided at the output stage of the speed controller VXPI in the X direction. In the exposure apparatus 100 of the present embodiment, when exposing a shot on the wafer W,
The reticle stage 27 and the XY stage 20 are synchronously scanned in opposite directions in the scanning direction, that is, in the X-axis direction. At this time, the reticle stage 27 changes the movable range of the reticle stage 27 once per shot. The reticle moves from end to end at a speed that is the reciprocal multiple (for example, 4 or 5 times) of the reduction magnification of the projection optical system PL at the speed of the XY stage 20, and the exposure is performed only in the constant speed range. The stage 27 performs three state transitions of accelerating from the stop state to the target speed, maintaining the target speed, and decelerating from the target speed to the stop state.
Immediately after the start of the movement and immediately before the stop, a large reaction force acts on the main frame 24 and the wafer base plate 6 via the invar 12, and vibration occurs in the body 40 including the wafer base plate 6. Therefore, the scan counter 66
Thus, the command value of the reaction force in the direction opposite to the acceleration of the reticle stage 27 is fed forward to the vibration control system, and the vibration of the stage 27 immediately after the start and immediately before the stop is suppressed.

FIG. 3 shows, as a comparative example, a speed control open loop in a control system of an exposure apparatus employing a conventional coil spring mount (a control system in which the vibration compensation system 60 is removed from the control system of FIG. 2). An example of a response (frequency response in an open loop) is shown in FIG. 4, and as a comparative example, a control system of a conventional exposure apparatus (a control system in which the vibration compensation system 60 is removed from the control system of FIG. 2). 3 shows an example of the speed control closed-loop response (frequency response in the closed loop) in the above. FIG. 5 shows a speed control open loop response in the control system (the control system in FIG. 2) of the exposure apparatus 100 of the present embodiment, and FIG. 6 shows the control system ( 2 shows the speed control closed-loop response in the control system of FIG. 2).

Looking at the frequency characteristic of the velocity closed-loop response in FIG. 4, it can be seen that the gain of the control band around 1 Hz is not sufficient. In this state, for example, when the stage performs an acceleration / deceleration movement, a residual vibration naturally occurs and appears as a damped vibration.

On the other hand, in the control system according to the present embodiment, the speed of the rigid mode of the body 40 (the point where the gain of the speed response reaches a peak, that is, the phase is 0) in the speed open loop response shown in FIG. It can be seen that the frequency at the point (°) is shifted by about 2 Hz to the lower frequency side as compared with the case of the conventional example in FIG. 3, and the control band (10 Hz) is seen from the velocity closed-loop response shown in FIG. 4), it can be seen at the same time that a sufficient gain can be secured unlike the case of FIG.

Thus, the exposure apparatus 100 of the present embodiment
Thus, the residual vibration generated in the body 40 due to the reaction force during the stage acceleration / deceleration can be ideally damped.

As described above, according to the exposure apparatus 10 of the present embodiment, the mount section 4 has the mechanical vibration isolating pad 8
In the case of a coil spring mount having a vibration sensor, an acceleration sensor as a sensor (vibration sensor) is attached to the body 40 to form a closed loop speed control servo system for controlling the vibration of the body 40. Even if there is mechanical resonance of the body 40, control characteristics that can secure a sufficient gain in the control band can be obtained. Therefore, despite using an inexpensive coil spring mount, it is possible to secure the same vibration damping performance of the body as using an air mount.

Therefore, according to the exposure apparatus 100 of the present embodiment, even when there is mechanical resonance of the body in a high frequency range, it is possible to effectively suppress vibration and perform exposure with high precision.

Further, in the exposure apparatus of the present embodiment, the scan counter 6 which feed-forward inputs a command value of thrust (counter force) in a direction opposite to the acceleration immediately before the start and immediately before the stop of the reticle stage 27 to the vibration control system.
The actuators 7A to 7A are controlled by the vibration control system so as to suppress the vibration generated on the main frame 24 and the wafer stage base plate 6 immediately after the movement of the reticle stage 27 starts and immediately before the stop.
D and 32A to 32C are drive-controlled. Further, even if the main frame 24 and the wafer stage base plate 6 are shaken due to damage to the counter force by the scan counter 66, the residual vibration can be effectively damped.

In the above embodiment, the vibration compensation system 60
Describes the case where the thrust command value determined based on the integral value of the output of the acceleration sensor, the damping coefficient of the vibration isolation pad, and the spring constant is feedforward input to the vibration control system. It is a matter of course that the thrust command value determined based on the differential value of the output of the above and the damping coefficient and the spring constant of the vibration damping pad may be fed forward to the vibration control system, and even in such a case, the same operation and effect as in the above embodiment can be obtained. be able to.

In the above-described embodiment, a case has been described in which a mechanical damper having a coil spring is used as the vibration damping pad 8. However, the present invention is not limited to this. Of course, a pneumatic damper provided with the above may be used. In such a case, it is possible to prevent the body from tilting due to the movement of the center of gravity accompanying the movement of the stage without using a device (so-called eccentric load counter) for controlling the actuator using a correction command value that is a function of the position of the stage. Will be able to do it. Therefore, an eccentric load counter becomes unnecessary.

Further, in the above-described embodiment, the case where the anti-vibration apparatus according to the present invention is applied to a step-and-scan type scanning exposure type projection exposure apparatus has been exemplified. The projection exposure apparatus described above can be suitably applied since the stage moves on the surface plate. In the case of the stepper type projection exposure apparatus, since the stage is stopped at the time of exposure because it is a batch exposure type, a scan counter is unnecessary.

The present invention is not applied only to the case where the body is prevented from swinging in six degrees of freedom. For example, when the stage is configured to move on the position of the center of gravity of the body, the apparatus main body does not necessarily swing in the direction of six degrees of freedom even if the stage moves. This is because it is clear that the solution principle works effectively. For this reason, the number of displacement sensors and acceleration sensors (vibration sensors) is not limited to six.

[0056]

As described above, according to the first to fourth aspects of the present invention, the frequency of the rigid body mode of the body is shifted to a low frequency in a pseudo manner, and the low frequency gain of the speed control loop is increased. There is an unprecedented excellent effect that it can be sufficiently secured.

In particular, according to the second aspect of the invention, there is also an effect that the residual vibration due to damage to the counterforce can be effectively damped.

According to the fourth aspect of the present invention, a so-called offset load counter becomes unnecessary.

According to the fifth aspect of the present invention, even when there is mechanical resonance of the body in a high frequency range, there is an effect that vibration can be effectively suppressed and exposure can be performed with high accuracy. .

Further, according to the present invention, even when there is mechanical resonance of the vibration isolation table in a high frequency range, the vibration isolation table can be effectively removed without vibrating the mechanical resonance. can do.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing an exposure apparatus according to an embodiment, partially cut away.

FIG. 2 is a block diagram showing a control system of the exposure apparatus of FIG.

FIG. 3 is a diagram showing an example of a speed control open loop response in a control system of an exposure apparatus employing a conventional coil spring mount as a comparative example.

FIG. 4 is a diagram showing an example of a speed control closed loop response in a control system of a conventional exposure apparatus as a comparative example.

FIG. 5 is a diagram illustrating a speed control open loop response in a control system of the exposure apparatus according to the embodiment.

FIG. 6 is a diagram illustrating a speed control closed loop response in a control system of the exposure apparatus according to the embodiment.

[Explanation of symbols]

 5A to 5C Acceleration sensor (sensor) 7A to 7D Actuator 8A to 8D Anti-vibration pad 10A to 10C Displacement sensor (sensor) 11 Control device (vibration control system) 20 XY stage (substrate stage) 24 Main frame (anti-vibration table) 27 Reticle stage (stage) 32A to 32C Actuator 40 Body (exposure device main body) 60 Vibration compensation system 66 Scan counter 100 Exposure device R Reticle (mask) PL Projection optical system Wafer W (photosensitive substrate)

Claims (6)

[Claims] 1. An anti-vibration table held horizontally via at least three anti-vibration pads; at least one stage moving on the anti-vibration table; and vertically moving the anti-vibration table at different locations. A plurality of actuators including at least three actuators to be driven; one or more sensors for detecting displacement or vibration of the anti-vibration table; and suppressing vibration of the anti-vibration table based on an output of the sensor. A vibration control system for driving and controlling each of the actuators; an output of the sensor and an elasticity of the vibration isolation pad so as to generate a thrust to the actuator to suppress the vibration of the vibration isolation table generated when the stage is accelerated or decelerated. A vibration compensation system that feed-forward inputs a thrust command value determined according to at least one of a coefficient and a damping coefficient to the vibration control system. 2. The anti-vibration apparatus according to claim 1, further comprising a scan counter which feed-forward inputs a command value of a reaction force in a direction opposite to an acceleration immediately after the start of movement of the stage and immediately before the stop to the vibration control system. 3. The vibration damping device according to claim 1, wherein the vibration damping pad is a mechanical damper having a coil spring mount. 4. The vibration damping device according to claim 1, wherein the vibration damping pad is a pneumatic damper provided with an air spring. 5. An exposure apparatus for transferring a pattern formed on a mask onto a photosensitive substrate on a substrate stage via a projection optical system, wherein the vibration isolation apparatus according to claim 1. An exposure apparatus, comprising: (1) as a vibration isolator of an exposure apparatus main body. 6. A vibration isolation method for a vibration isolation table that is supported via a vibration isolation pad and an actuator and has a stage that moves on an upper surface thereof, based on a sensor output for detecting displacement or vibration of the vibration isolation table. Providing a thrust command value determined according to at least one of an elastic coefficient and a damping coefficient of the vibration isolating pad to the actuator so as to suppress shaking of the vibration isolating table generated during acceleration and deceleration of the stage. The vibration isolation method of the vibration isolation table.