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| United States Patent | 5812420 |
| Link to this page | http://www.wikipatents.com/5812420.html |
| Inventor(s) | Takahashi; Masato (Yokohama-shi, JP) |
| Abstract | A position of movement of a stage is measured by an interferometer when the
stage placed on a vibration-preventive pedestal of an exposure apparatus
is moved. An output of the interferometer is multiplied by K so as to
correct an amount of inclination of the vibration-preventive pedestal
caused by movement of a position of a center of gravity during the
movement of the stage, and an obtained value is feedforward-inputted into
a vibration control system of a control unit. The vibration control system
controls actuators on the basis of outputs of a displacement sensor and a
vibration sensor and the feedforward-inputted value so that vibration of
the vibration-preventive pedestal is suppressed. A vibration-compensating
system multiplies, by g, displacements .theta..sub.x, .theta..sub.y in a
direction of inclination with respect to a horizontal plane obtained on
the basis of outputs of three vertical displacement sensors. Obtained
results are subtracted from outputs of horizontal acceleration sensors.
Thus gravitational acceleration components can be removed from the outputs
of the horizontal sensors. The suppressing effect on disturbance vibration
can be improved without being affected by the movement of the position of
the center of gravity of the main apparatus body associated with the
movement of the stage. |
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Title Information  |
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Drawing from US Patent 5812420 |
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Vibration-preventive apparatus and exposure apparatus |
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| Publication Date |
September 22, 1998 |
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| Filing Date |
September 3, 1996 |
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| Priority Data |
Sep 05, 1995[JP]7-251887
Sep 05, 1995[JP]7-251888 |
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Title Information |
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References |
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| *references marked with an asterisk below are user-added references |
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U.S. References |
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| | Reference | Relevancy | Comments | Reference | Relevancy | Comments | 5579084
Takahashi
355/53
Nov,1996 |  Your vote accepted
[0 after 0 votes] | | 5539497
Nishi
355/53
Jul,1996 | Your vote accepted
[0 after 0 votes] | | 5502313
Nakamura
250/559.26
Mar,1996 | Your vote accepted
[0 after 0 votes] | | 5502311
Imai
250/548
Mar,1996 | Your vote accepted
[0 after 0 votes] | | 5478043
Wakui
248/550
Dec,1995 | Your vote accepted
[0 after 0 votes] | | 5473424
Okumura
356/139.03
Dec,1995 | Your vote accepted
[0 after 0 votes] | | 5467720
Korenaga
Nov,1995 | Your vote accepted
[0 after 0 votes] | | 5187519
Takabayashi
355/53
Feb,1993 | Your vote accepted
[0 after 0 votes] | | 5172160
Van Eijk
355/53
Dec,1992 | Your vote accepted
[0 after 0 votes] | | 5121898
Yasuda
248/550
Jun,1992 | Your vote accepted
[0 after 0 votes] | | 5060519
Chojitani
73/662
Oct,1991 | Your vote accepted
[0 after 0 votes] | | | | | |
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Public's "Guesstimation" of Royalty Value
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Market Review |
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Technical Review |
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Claims |
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What is claimed is:
1. A vibration-preventive apparatus comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
at least one stage movable on the vibration-preventive pedestal;
at least three actuators for moving the vibration-preventive pedestal in a
vertical direction;
at least one displacement sensor for detecting displacement of the
vibration-preventive pedestal;
at least one vibration sensor for detecting vibration of the
vibration-preventive pedestal;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensor and the vibration sensor so
that the vibration of the vibration-preventive pedestal is suppressed;
a position-measuring unit for measuring a position of the at least one
stage; and
a vibration-compensating system for forecasting an amount of inclination of
the vibration-preventive pedestal caused by movement of a position of a
center of gravity during movement of the stage on the basis of an output
of the position-measuring unit, and inputting a command value to correct
the amount of inclination into the vibration control system in a
feedforward manner.
2. The vibration-preventive apparatus according to claim 1, further
comprising a scan counter for feedforward-inputting, into the vibration
control system, command values for reaction forces having directions
opposite to those of accelerations immediately after start and immediately
before stop of the movement of the stage.
3. The vibration-preventive apparatus according to claim 1, wherein the
vibration control system comprises:
a first coordinate-converting unit for converting the output of the
displacement sensor into displacements in directions of degrees of freedom
of the center of gravity of the vibration-preventive pedestal;
a first velocity converting unit for determining velocity command values
obtained on the basis of differences between outputs from the first
coordinate-converting unit and target values of the position of the center
of gravity of the vibration-preventive pedestal;
a second coordinate-converting unit for converting the output of the
vibration sensor into accelerations for each of the degrees of freedom of
the center of gravity of the vibration-preventive pedestal;
a second velocity converting unit for determining velocities of the center
of gravity of the vibration-preventive pedestal from the accelerations of
the second coordinate-converting unit;
subtracters for determining velocity deviations for each of the degrees of
freedom of the center of gravity of the vibration-preventive pedestal from
the velocities and the velocity command values; and
velocity controllers for generating, from outputs of the subtracters,
velocity control amounts of the center of gravity of the
vibration-preventive pedestal for each of the degrees of freedom; and
wherein the vibration-compensating system feedforward-inputs command values
to correct the amount of inclination obtained from the output of the
position-measuring unit.
4. The vibration-preventive apparatus according to claim 1, further
comprising at least one actuator for moving the vibration-preventive
pedestal in X and Y directions perpendicular to the vertical direction
respectively.
5. In an exposure apparatus that forms a pattern onto a photosensitive
substrate by projecting illuminating light through a projection optical
system, a vibration control apparatus comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
a substrate stage, movable on the vibration-preventive pedestal, for
holding the photosensitive substrate;
at least three actuators for moving the vibration-preventive pedestal in a
vertical direction;
at least one displacement sensor for detecting displacement of the
vibration-preventive pedestal;
at least one vibration sensor for detecting vibration of the
vibration-preventive pedestal;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensor and the vibration sensor so
that the vibration of the vibration-preventive pedestal is suppressed;
a position-measuring unit for measuring a position of the substrate stage;
and
a vibration-compensating system for forecasting an amount of inclination of
the vibration-preventive pedestal caused by movement of a position of a
center of gravity during movement of the substrate stage on the basis of
an output of the position-measuring unit, and inputting a command value to
correct the amount of inclination into the vibration control system in a
feedforward manner.
6. The exposure apparatus according to claim 5, further comprising a scan
counter for feedforward-inputting, into the vibration control system,
command values for reaction forces having directions opposite to those of
accelerations immediately after start and immediately before stop of the
movement of the substrate stage.
7. The exposure apparatus according to claim 5, further comprising a mask
stage movable in synchronization with the substrate stage, and a
position-measuring unit for measuring a position of the mask stage,
wherein the vibration-compensating system forecasts an amount of
inclination of the vibration-preventive pedestal caused by movement of a
position of a center of gravity during movement of the substrate stage and
the mask stage on the basis of outputs of the position-measuring units for
the respective stages, and inputs a command value to correct the amount of
inclination into the vibration control system in a feedforward manner.
8. The exposure apparatus according to claim 7, further comprising a scan
counter for feedforward-inputting, into the vibration control system,
command values for reaction forces having directions opposite to those of
accelerations immediately after start and immediately before stop of the
movement of the substrate stage and the mask stage.
9. The exposure apparatus according to claim 5, wherein the vibration
control system comprises:
a first coordinate-converting unit for converting the output of the
displacement sensor into displacements in directions of degrees of freedom
of the center of gravity of the vibration-preventive pedestal;
a first velocity converting unit for determining velocity command values
obtained on the basis of differences between outputs from the first
coordinate-converting unit and target values of the position of the center
of gravity of the vibration-preventive pedestal;
a second coordinate-converting unit for converting the output of the
vibration sensor into accelerations for each of the degrees of freedom of
the center of gravity of the vibration-preventive pedestal;
a second velocity converting unit for determining velocities of the center
of gravity of the vibration-preventive pedestal from the accelerations of
the second coordinate-converting unit;
subtracters for determining velocity deviations for each of the degrees of
freedom of the center of gravity of the vibration-preventive pedestal from
the velocities and the velocity command values; and
velocity controllers for generating, from outputs of the subtracters,
velocity control amounts of the center of gravity of the
vibration-preventive pedestal for each of the degrees of freedom; and
wherein the vibration-compensating system feedforward-inputs command values
to correct the amount of inclination obtained from the output of the
position-measuring unit.
10. A vibration-preventive apparatus comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
at least three actuators for driving the vibration-preventive pedestal in a
vertical direction at different positions;
at least three vertical displacement sensors for detecting vertical
displacement of the vibration-preventive pedestal at different points;
a vibration sensor for detecting at least an acceleration of the
vibration-preventive pedestal in a horizontal plane;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensors and the vibration sensor so
that vibration of the vibration-preventive pedestal is suppressed; and
a vibration-compensating system for removing a gravitational acceleration
component contained in a detected value obtained by the vibration sensor
on the basis of displacement in a direction of inclination with respect to
the horizontal plane obtained on the basis of the outputs of the three
vertical displacement sensors.
11. The vibration-preventive apparatus according to claim 10, wherein the
vibration sensor comprises an acceleration sensor for an X direction and
an acceleration sensor for a Y direction, and wherein the vibration
control system comprises:
a first coordinate-converting unit for converting the output of the
displacement sensor into displacements in directions of degrees of freedom
of the center of gravity of the vibration-preventive pedestal;
a first velocity converting unit for determining velocity command values
obtained on the basis of differences between outputs from the first
coordinate-converting unit and target values of the position of the center
of gravity of the vibration-preventive pedestal;
a second coordinate-converting unit for converting the output of the
vibration sensor into accelerations for each of the degrees of freedom of
the center of gravity of the vibration-preventive pedestal;
a second velocity converting unit for determining velocities of the center
of gravity of the vibration-preventive pedestal from the accelerations of
the second coordinate-converting unit;
subtracters for determining velocity deviations for each of the degrees of
freedom of the center of gravity of the vibration-preventive pedestal from
velocities of the center of gravity obtained from the second velocity
converting unit;
velocity controllers for generating, from outputs of the subtracters,
velocity control amounts of the center of gravity of the
vibration-preventive pedestal for each of the degrees of freedom; and
wherein the vibration-compensating system comprises respective amplifiers
for multiplying, by a gravitational acceleration, an output of an
inclination component .theta..sub.x about an X axis and an output of an
inclination component .theta..sub.y about a Y axis outputted from the
first coordinate-converting unit, and subtracters for determining the
differences between outputs from the respective amplifiers and outputs of
the acceleration sensors for the X and Y directions so that outputs of the
subtracters are outputted to the second coordinate-converting unit.
12. The vibration-preventive apparatus according to claim 10, further
comprising at least one stage movable on the vibration-preventive
pedestal.
13. The vibration-preventive apparatus according to claim 10, further
comprising at least one actuator for moving the vibration-preventive
pedestal in X and Y directions perpendicular to the vertical direction
respectively.
14. The vibration-preventive apparatus according to claim 10, further
comprising a vibration sensor for detecting an acceleration of the
vibration-preventive pedestal in the vertical direction.
15. In an exposure apparatus that forms a pattern onto a photosensitive
substrate by projecting illuminating light through a projection optical
system, a vibration control apparatus comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
at least one stage, movable on the vibration-preventive pedestal, for
holding the photosensitive substrate;
at least three actuators for driving the vibration-preventive pedestal in a
vertical direction at different positions;
at least three vertical displacement sensors for detecting vertical
displacement of the vibration-preventive pedestal at different points;
a vibration sensor for detecting at least an acceleration of the
vibration-preventive pedestal in a horizontal plane;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensors and the vibration sensor so
that vibration of the vibration-preventive pedestal is suppressed; and
a vibration-compensating system for removing a gravitational acceleration
component contained in a detected value obtained by the vibration sensor
on the basis of displacement in a direction of inclination with respect to
the horizontal plane obtained on the basis of the outputs of the three
vertical displacement sensors.
16. The exposure apparatus according to claim 15, further comprising a
position-measuring unit for measuring a position of the at least one
stage, wherein the vibration-compensating system further forecasts an
amount of inclination of the vibration-preventive pedestal caused by
movement of a position of a center of gravity during movement of the at
least one stage on the basis of an output of the stage position-measuring
unit, and inputs a command value to correct the amount of inclination into
the vibration control system in a feedforward manner.
17. The exposure apparatus according to claim 16, provided as a scanning
type exposure apparatus, further comprising a mask stage movable in
synchronization with the at least one stage as a substrate stage, and a
position-measuring unit for the mask stage.
18. The exposure apparatus according to claim 17, further comprising a scan
counter for feedforward-inputting, into the vibration control system,
command values for reaction forces having directions opposite to those of
accelerations immediately after start and immediately before stop of the
movement of the substrate stage and the mask stage.
19. The exposure apparatus according to claim 15, wherein the vibration
sensor comprises an acceleration sensor for an X direction and an
acceleration sensor for a Y direction wherein the vibration control system
comprises:
a first coordinate-converting unit for converting the output of the
displacement sensor into displacements in directions of degrees of freedom
of the center of gravity of the vibration-preventive pedestal;
a first velocity converting unit for determining velocity command values
obtained on the basis of differences between outputs from the first
coordinate-converting unit and target values of the position of the center
of gravity of the vibration-preventive pedestal;
a second coordinate-converting unit for converting the output of the
vibration sensor into accelerations for each of the degrees of freedom of
the center of gravity of the vibration-preventive pedestal;
a second velocity converting unit for determining velocities of the center
of gravity of the vibration-preventive pedestal from the accelerations of
the second coordinate-converting unit;
subtracters for determining velocity deviations for each of the degrees of
freedom of the center of gravity of the vibration-preventive pedestal from
velocities of the center of gravity obtained from the second velocity
converting unit;
velocity controllers for generating, from outputs of the subtracters,
velocity control amounts of the center of gravity of the
vibration-preventive pedestal for each of the degrees of freedom; and
wherein the vibration-compensating system comprises respective amplifiers
for multiplying, by a gravitational acceleration, an output of an
inclination component .theta..sub.x about an X axis and an output of an
inclination component .theta..sub.y about a Y axis outputted from the
first coordinate-converting unit, and subtracters for determining the
differences between outputs from the respective amplifiers and outputs of
the acceleration sensors for the X and Y directions so that outputs of the
subtracters are outputted to the second coordinate-converting unit.
20. The exposure apparatus according to claim 15, further comprising at
least one actuator for moving the vibration-preventive pedestal in X and Y
directions perpendicular to the vertical direction respectively.
21. The exposure apparatus according to claim 15, further comprising a
vibration sensor for detecting an acceleration of the vibration-preventive
pedestal in the vertical direction.
22. A method of compensating for vibrations in an apparatus having a
pedestal, at least one movable stage movable on the pedestal, at least
three actuators for vertically moving the pedestal, at least one
displacement sensor for detecting displacement of the pedestal and at
least one vibration sensor for detecting vibration of the pedestal, the
method comprising:
measuring a position of the at least one stage;
forecasting an amount of inclination of the pedestal based on the position
of the at least one stage; and
controlling the actuators on the basis of outputs from the displacement
sensor, the vibration sensor and the forecast amount of inclination to
suppress vibration of the pedestal and to correct the amount of
inclination in a feedforward manner.
23. The method of claim 22, wherein controlling the actuators comprises:
converting the output of the displacement sensor into displacements in the
directions of degrees of freedom of a center of gravity of the pedestal;
determining velocity command values on the basis of differences between the
displacements and target values of the position of the center of gravity
of the pedestal;
converting the output of the vibration sensor into accelerations for each
of the degrees of freedom of the center of gravity of the pedestal;
determining velocities of the center of gravity of the pedestal from the
accelerations;
determining deviations of the center of gravity of the pedestal for each of
the degrees of freedom from the velocity command values and the velocities
of the center of gravity of the pedestal; and
generating velocity control amounts of the center of gravity for each of
the degrees of freedom.
24. A method of compensating for vibrations in an apparatus having a
pedestal, at least three actuators for vertically moving the pedestal, at
least three vertical displacement sensors for detecting vertical
displacement of the pedestal at different points, and at least one
vibration sensor for detecting at least an acceleration of the pedestal in
a horizontal plane, the method comprising:
removing a gravitational acceleration component contained in a detected
value obtained by the vibration sensor based on a direction of inclination
of the pedestal with respect to the horizontal plane obtained from the
output of the vertical displacement sensors; and
controlling the actuators on the basis of outputs from the displacement
sensor and the vibration sensor, with the gravitational acceleration
component removed, to suppress vibration of the pedestal.
25. The method of claim 24, wherein removing the gravitational acceleration
component comprises:
converting the output of the vibration sensor into accelerations for each
of the degrees of freedom of a center of gravity of the pedestal;
multiplying an inclination component about an X axis and an inclination
component about a Y axis by a gravitational acceleration; and
determining differences between the multiplied inclinations and the
accelerations. |
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Claims |
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Description |
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BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a vibration-preventive apparatus and an
exposure apparatus. In particular, the present invention relates to a
vibration-preventive apparatus of the so-called active system in which a
vibration-preventive pedestal is driven by actuators so that vibration of
the vibration-preventive pedestal is counteracted, and an exposure
apparatus provided with the vibration-preventive apparatus.
2. Description of the Related Art
Precision mechanical equipment such as a reduction projection type exposure
apparatus of the step-and-repeat system, i.e., a so-called stepper is
developed to have high accuracy. As a result, it becomes necessary to
insulate microvibration acting from an installation floor to a platform
(vibration-preventive pedestal) at a micro G level. A vibration-preventive
pad for supporting the vibration-preventive pedestal of a
vibration-preventive apparatus includes various ones such as a pneumatic
damper and a mechanical damper comprising a compressive coil spring
inserted in a damping liquid. The vibration-preventive pad itself has a
centering function to some extent. Especially, an air spring type
vibration-preventive apparatus provided with a pneumatic damper has a
spring constant which can be set to be small, and hence it insulates
vibration of about 10 Hz or more. Accordingly, the vibration-preventive
apparatus of this type is widely used for supporting precision mechanical
equipment. Recently, in order to break through the limit of the
conventional passive vibration-preventive apparatus, an active
vibration-preventive apparatus has been proposed (for example, see U.S.
patent application Ser. No. 539080 filed by the same applicant as that of
this application). The active vibration-preventive apparatus performs
vibration control by detecting vibration of a vibration-preventive
pedestal with a sensor, and driving an actuator on the basis of an output
of the sensor. The active vibration-preventive apparatus can provide an
ideal vibration-insulating effect with no resonance peak in a low
frequency control zone.
As for the stepper, an XY stage (wafer stage), which undergoes large
acceleration and deceleration, is carried on a platform supported by
vibration-preventive pads, and the position of the center of gravity of a
main exposure apparatus body moves simultaneously with movement of the XY
stage. When the position of the center of gravity of the main apparatus
body is changed in accordance with the movement of the stage, the active
vibration-preventive apparatus makes positioning at an initial position by
the aid of a position control loop. Increase in the amount of movement of
the stage involves increase in the amount of change in the position of the
center of gravity of the main apparatus body, resulting in inclination of
the main apparatus body. In such a situation, the conventional active
vibration-preventive apparatus can enjoy improvement in response
characteristics of position control by increasing the gain of the position
control loop. However, increase in the gain of the position control loop
allows floor vibration to be transmitted to the main apparatus body,
resulting in deterioration of vibration-preventive performance.
Accordingly, increase in the gain of the position control loop has a
limit, and involves, for example, a fear for occurrence of an
inconvenience that the balance of force between the main apparatus body
and the actuator is destroyed, and the main apparatus body is deviated
from the initial position, due to consequent movement of the position of
the center of gravity of the main apparatus body.
The stepper suffers swinging of its platform at a large amplitude caused by
a disturbance force during, for example, quick acceleration and quick
deceleration of an XY stage. The active vibration-preventive apparatus
often uses an acceleration sensor as a vibration sensor. Especially, in
the case of an exposure apparatus, horizontal acceleration sensors for
detecting accelerations in X and Y two-dimensional directions in a
horizontal plane are sometimes arranged on a platform held horizontally on
vibration-preventive pads. In such an arrangement, when the
vibration-preventive pedestal is swung at a large amplitude and inclined,
the horizontal acceleration sensor inevitably detects a component of the
gravitational acceleration in proportion to an amount of inclination of
the platform, together with an acceleration of its original detecting
direction. It is desirable to suppress the component of the gravitational
acceleration to be as small as possible because the component badly
affects a vibration control loop. However, it is impossible to find a
conventional active vibration-preventive apparatus which is so far
directed to the component of the gravitational acceleration.
SUMMARY OF THE INVENTION
An object of the present invention is to provide a vibration-preventive
apparatus and an exposure apparatus provided therewith which make it
possible to dissolve the inconvenience involved in the conventional art
and improve the suppressing (vibration-damping) effect on disturbance
vibration without being affected by the movement of the position of the
center of gravity of the main apparatus body caused by the movement of the
stage. Another object of the present invention is to provide a
vibration-preventive apparatus and an exposure apparatus provided
therewith which make it possible to improve the suppressing
(vibration-damping) effect on disturbance vibration without being affected
by the inclination of the vibration-preventive pedestal.
According to a first aspect of the present invention, there is provided a
vibration-preventive apparatus comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
at least one stage movable on the vibration-preventive pedestal;
at least three actuators for moving the vibration-preventive pedestal in a
vertical direction;
at least one displacement sensor for detecting displacement of the
vibration-preventive pedestal;
at least one vibration sensor for detecting vibration of the
vibration-preventive pedestal;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensor and the vibration sensor so
that the vibration of the vibration-preventive pedestal is suppressed;
a position-measuring unit for measuring a position of the at least one
stage; and
a vibration-compensating system for forecasting an amount of inclination of
the vibration-preventive pedestal caused by movement of a position of a
center of gravity during movement of the stage on the basis of an output
of the position-measuring unit, and inputting a command value to correct
the amount of inclination into the vibration control system in a
feedforward manner.
When the stage is moved in the vibration-preventive apparatus of the
present invention, the position of movement of the stage is measured by
the position-measuring unit. The vibration-compensating system forecasts
the amount of inclination of the vibration-preventive pedestal caused by
movement of the position of the center of gravity during movement of the
stage on the basis of the output of the position-measuring unit, and
inputs the command value to correct the amount of inclination into the
vibration control system in a feedforward manner. The vibration control
system drives and controls the respective actuators on the basis of the
outputs of the displacement sensor and the vibration sensor and the
feedforward-inputted command value so that the vibration of the
vibration-preventive pedestal is suppressed. Thus the amount of
inclination of the vibration-preventive pedestal caused by the movement of
the position of the center of gravity during the movement of the stage is
corrected together with the vibration of the vibration-preventive
pedestal. In this arrangement, it is unnecessary to excessively increase
the gain of the vibration control system. Accordingly, the
vibration-preventive performance is not deteriorated as well. Therefore,
it is possible to improve the suppressing (vibration-damping) effect on
disturbance vibration without being affected by the movement of the
position of the center of gravity of the main apparatus body involved in
the movement of the stage.
The vibration-preventive apparatus described above may further comprise a
scan counter for feedforward-inputting, into the vibration control system,
command values for reaction forces having directions opposite to those of
accelerations immediately after start and immediately before stop of the
movement of the stage. The scan counter serves to feedforward-input, into
the vibration control system, the command values for the reaction forces
having the directions opposite to those of the accelerations immediately
after start and immediately before stop of the movement of the stage.
Accordingly, the vibration control system drives and controls the
actuators so as to suppress vibrations generated on the
vibration-preventive pedestal immediately after start and immediately
before stop of the movement of the stage. Therefore, the vibration-damping
effect can be further improved.
According to a second aspect of the present invention, there is provided an
exposure apparatus for transferring a pattern formed on a mask onto a
photosensitive substrate through a projection optical system, comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
a substrate stage, movable on the vibration-preventive pedestal, for
holding the photosensitive substrate;
at least three actuators for moving the vibration-preventive pedestal in a
vertical direction;
at least one displacement sensor for detecting displacement of the
vibration-preventive pedestal;
at least one vibration sensor for detecting vibration of the
vibration-preventive pedestal;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensor and the vibration sensor so
that the vibration of the vibration-preventive pedestal is suppressed;
a position-measuring unit for measuring a position of the substrate stage;
and
a vibration-compensating system for forecasting an amount of inclination of
the vibration-preventive pedestal caused by movement of a position of a
center of gravity during movement of the substrate stage on the basis of
an output of the position-measuring unit, and inputting a command value to
correct the amount of inclination into the vibration control system in a
feedforward manner. The exposure apparatus of the present invention is
provided with the vibration-preventive apparatus excellent in the
vibration-damping effect. Accordingly, the exposure apparatus can transfer
a mask pattern onto a photosensitive substrate accurately and precisely.
Especially, the exposure apparatus of the present invention is preferably
used as a scanning type exposure apparatus in which a mask stage and a
photosensitive substrate move synchronously in the scanning direction.
According to a third aspect of the present invention, there is provided a
vibration-preventive apparatus comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
at least three actuators for driving the vibration-preventive pedestal in a
vertical direction at different positions;
at least three vertical displacement sensors for detecting vertical
displacement of the vibration-preventive pedestal at different points;
a vibration sensor for detecting at least an acceleration of the
vibration-preventive pedestal in a horizontal plane;
a vibration control system for controlling the respective actuators on the
basis of outputs of the displacement sensors and the vibration sensor so
that vibration of the vibration-preventive pedestal is suppressed; and
a vibration-compensating system for removing a gravitational acceleration
component contained in a detected value obtained by the vibration sensor
on the basis of displacement in a direction of inclination with respect to
the horizontal plane obtained on the basis of the outputs of the three
vertical displacement sensors.
According to the vibration-preventive apparatus described above, when the
vibration-preventive pedestal swings, the vibration control system drives
and controls the respective actuators on the basis of the outputs of the
displacement sensors and the vibration sensor so that the vibration of the
vibration-preventive pedestal is suppressed. In this arrangement, the
vibration-compensating system removes the gravitational acceleration
component contained in the detected value obtained by respective
horizontal acceleration sensors (vibration sensor) on the basis of the
displacement in the direction of inclination with respect to the
horizontal plane obtained on the basis of the outputs of the three
vertical displacement sensors. Therefore, the vibration control system
drives and controls the respective actuators on the basis of the output of
the horizontal acceleration sensors from which the gravitational
acceleration component has been removed. Accordingly, the suppressing
(vibration-damping) effect on disturbance vibration is improved without
being affected by the inclination of the vibration-preventive pedestal.
According to a fourth aspect of the present invention, there is provided an
exposure apparatus for transferring a pattern formed on a mask onto a
photosensitive substrate through a projection optical system, comprising:
a vibration-preventive pedestal held horizontally through at least three
vibration-preventive pads;
at least one stage, movable on the vibration-preventive pedestal, for
holding the photosensitive substrate;
at least three actuators for driving the vibration-preventive pedestal in a
vertical direction at different positions;
at least three vertical displace | | |
