JP2001345244A - Method of controlling stage, stage device, aligner, and method of manufacturing device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the shaking of a stage during stepping motions. SOLUTION: While a substrate, such as the wafer, etc., to be exposed is held on a stage 1, stepping motions and scanning motions are alternately performed in accordance with commands given from a stage sequence controller 30. The controller 30 is composed of a position sensor 2, a motor 3, a target speed generator 7, etc., and controls the position of the stage 1 on a vibration- absorbing table 10. Though centroid correction is performed during scanning motions by feeding back the target moving distance, etc., of the stage 1 to the control systems of the air springs 12a and 12b of the table 10, the shaking of the stage 1 is prevented by enlarging the position control gain of the table 10 by means of a gain setter 31 during the stepping motions.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stage control method for controlling an XY stage or the like with an anti-vibration device used for an exposure apparatus for manufacturing a semiconductor device or the like.
The present invention relates to a stage apparatus, an exposure apparatus, and a device manufacturing method.

[0002]

2. Description of the Related Art A stage apparatus such as an XY stage of an exposure apparatus for manufacturing a semiconductor device or the like has an intermittent operation of a step-and-repeat or a step-and-scan as a stage drive mode, and performs a repetitive step movement, It should also be noted that the vibration generated due to the scanning operation causes the vibration of the anti-vibration table supporting the XY stage and the like. Exposure cannot be performed if the vibration of the vibration isolation table does not subside.Therefore, the vibration isolation table is provided with vibration control for external vibration and control for forced vibration due to the movement of the stage equipment on the vibration control table. It is required to realize the balance with the vibration.

[0003] Vibration isolation tables are generally classified into passive vibration isolation tables and active vibration isolation tables. However, they are required for high-precision positioning, high-accuracy scanning, and high-speed movement of an XY stage or the like that holds a wafer or the like. In order to respond, in recent years, there is a tendency to use an active vibration isolation table.

[0004] Actuators for driving the vibration isolation table include an air spring, a linear motor, a voice coil motor, and a piezoelectric element.

FIG. 6 shows a stage device having an air spring type vibration isolator according to a conventional example using an air spring as its actuator. This stage device is an original plate such as a mask by exposure light generated from a light source (not shown). And a stage 101 for holding a substrate such as a wafer to which the pattern is transferred.

The stage 101 performs a scanning operation for scanning the substrate together with the original during exposure, and a step operation for changing the exposure area.

[0007] A vibration isolation table 110 for supporting the stage 101
Includes air spring-type support legs 111a, 111b, which are air springs 112a, 112b,
Servo valves 113a and 113b for supplying and exhausting air serving as a working fluid to both of them, position sensors 114a and 114b for measuring vertical displacement of the vibration isolation table 110 at a plurality of measurement points, respectively, mechanical springs 115a and 115a for preload.
15b, an air spring type support leg 111 including the air springs 112a, 112b and mechanical springs 115a, 115b for preloading.
a, 111b, and acceleration sensors 117a, 116b,
17b.

The control unit of the stage 101 that moves in the X and Y directions on the vibration isolation table 110 includes a position sensor 102 for measuring the horizontal displacement of the stage 101, a motor 103 for driving the stage 101, and a displacement amplifier 1 for amplifying the stage displacement.
04, PID compensator 105, amplifier 106, stage 1
A target speed generator 107 for generating a target speed of No. 01 and an integrator 108 are provided.

Also, air spring type support legs 111a, 111
b is controlled by displacement amplifiers 121a and 121a.
b, displacement decomposer 122, PI compensators 123a, 123
b, filters 124a and 124b, acceleration decomposer 12
5. Target position setting device 128 for setting the target position of thrust distributor 126, amplifiers 127a and 127b, and vibration isolation table 110
And a feedforward control system having a filter 129 having a predetermined appropriate gain and time constant is provided between the control unit and the control unit of the stage 101.

The operation of the above air spring type vibration damping device will be described. The outputs of the acceleration sensors 117a and 117b are output to a filter 124 having a predetermined appropriate gain and time constant, respectively.
a, 124b and input to the acceleration decomposer 125. Here, the two inputs are calculated by a 2 × 2 matrix operation to calculate the vertical acceleration of the vibration isolation table 110 and the angle around an axis passing through the center of gravity of the vibration isolation table 110 and perpendicular to the operation direction of the stage 101 in the horizontal plane. It is decomposed into acceleration, and is negatively fed back to the stage before the thrust distributor 126. Damping is added by this acceleration feedback loop.

The outputs of the position sensors 114a and 114b are
The signals are input to the displacement decomposer 122 through the displacement amplifiers 121a and 121b, respectively. Here, the vertical (Z-axis) displacement of the vibration isolation table 110 by a 2 × 2 matrix operation,
It is decomposed into a rotational displacement about an axis (about the X axis) perpendicular to the horizontal direction with respect to the operation direction (Y axis direction) of the stage 101 through the center of gravity of the vibration isolation table 110. The target position setting device 128 sets the target positions of the vertical displacement and the rotational displacement, and a deviation signal between the output of the displacement decomposer 122 and the input of the thrust distributor 126 through the PI compensators 123a and 123b. . Here, the 2 × 2 matrix operation passes through the vertical thrust target value and the center of gravity of the
The thrust target value in the rotation direction about the axis perpendicular to the horizontal direction with respect to the operation direction of 01 is distributed to the drive target values of the air springs 112a and 112b. The distributed drive target values are respectively supplied to the servo valves 113a and 127b by the amplifiers 127a and 127b.
a, 113b are converted into drive currents for the servo valve 11
The air springs 112a, 1b are opened and closed by opening and closing the valves 3a, 113b.
The pressure in 12b is adjusted, and the anti-vibration table 110 can hold the desired position and posture set by the target position setting device 128 without a steady-state deviation.

Here, P of the PI compensators 123a and 123b means proportional, and I means integral operation. The PI compensator 123a operates as a control compensator for the vertical displacement of the anti-vibration table 110, and the PI compensator 123b operates as a control compensator for the pitching of the anti-vibration table 110, that is, the rotational displacement.

Further, the output of the position sensor 102 passes through the displacement amplifier 104, and the deviation from the target position signal generated by the integrator 108 is input to the PID compensator 105. PI
The output of the D compensator 105 passes through the amplifier 106 to the motor 1
The stage 101 is driven via the control circuit 03.

Here, P of the PID compensator 105 is proportional,
I means integration and D means differentiation.

A target speed generator 107 generates a target speed of the stage 101 based on an operation profile generated by the stage sequence controller. The target speed of the stage 101 is integrated by the integrator 108 to become the target position of the stage 101. Further, the target speed of the stage 101 is fed forward through a filter 129 to a control system for the rotational displacement for correcting the center of gravity for preventing pitching of the vibration isolation table 110.

FIG. 7B shows the target speed generated by the target speed generator 107 with the horizontal axis representing time.
This speed pattern is well known as a trapezoidal speed pattern. FIGS. 7A and 7C respectively show 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 is converted to a target position through the integrator 108 and input to the control system of the stage 101.

Generally, in the equilibrium state of the air spring,
It is known that the transfer function from the input current I of the servo valve to the air spring pressure P can be approximated as an integral characteristic represented by the following equation (1).

[0018]

(Equation 1) (However, G _q is of the servo valve flow gain, k is the specific heat ratio of air, P ₀ is the air spring pressure in the equilibrium state, V ₀
Is an air spring volume in an equilibrium state, and s is a Laplace operator. )

The target speed fed forward to the control system for controlling the rotational displacement of the vibration isolation table 110 is the air spring 11
Since the integration is performed by the integration characteristics of 2a and 112b, feedforward of the target speed is equivalent to applying a rotational torque proportional to the position of the stage 101 to the vibration isolation table 110. By the feedforward input of the target speed, the rotational moment generated by the movement of the stage 101 can be canceled.

In this way, it is possible to effectively suppress the vibration of the vibration isolation table 110 due to the movement of the center of gravity accompanying the driving of the stage (see Japanese Patent Application Laid-Open No. H11-264444).

[0021]

However, according to the above-mentioned prior art, in a semiconductor exposure apparatus or the like, when the moving distance of the stage is very short compared to its moving range as in a step operation without exposure. However, since the pressure change speed of the air spring is slower than the moving speed of the stage, there is an unsolved problem that the above-described feedforward control causes the anti-vibration table to swing instead.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned unsolved problems of the prior art, and a stage capable of effectively avoiding a swing caused by a low response speed of an actuator such as an air spring of a vibration isolator. It is an object to provide a control method, a stage apparatus, an exposure apparatus, and a device manufacturing method.

[0023]

In order to achieve the above object, a stage control method according to the present invention comprises a base, a stage moving on the base, a stage control system for controlling the position of the stage, A vibration isolator having an actuator for maintaining the position and orientation of the platform, a platform control system for controlling the actuator, and a feed for feed-forward input of a target value of the stage control system to the platform control system In a stage device having a forward control system, a control function of the feedforward control system is adjusted based on at least one of a target moving distance and a target moving speed of the stage and a response frequency of the actuator. I do.

The stage apparatus of the present invention includes a base, a stage moving on the base, a stage control system for controlling the position of the stage, and an actuator for maintaining the position and posture of the base. A vibration isolation device, a platform control system for controlling the actuator, a feedforward control system for feedforward inputting a target value of the stage control system to the platform control system, and a target value of the stage control system. And adjusting means for adjusting the control function of the feedforward control system.

Preferably, the adjusting means is configured to change the gain of the board control system.

The adjusting means may be configured to perform ON / OFF control of the feedforward control system.

[0027] The actuator may include an air spring.

When the target moving distance of the stage is smaller than a predetermined value, the gain of the board control system is preferably increased.

When the target moving distance of the stage is smaller than a predetermined value, the feedforward control system may be turned off.

The feedforward control system may be configured to control the pitching of the base.

An exposure apparatus according to the present invention comprises a step-and-
A scanning type exposure apparatus, a base, a stage moving on the base, a stage control system for controlling a position of the stage, and an exposure unit for exposing a substrate to be exposed held on the stage. A vibration isolator having an actuator for maintaining the position and orientation of the platform, a platform control system for controlling the actuator, and feedforward input of target values of the stage control system to the platform control system. It is characterized by having a feedforward control system and adjusting means for adjusting a control function of the feedforward control system based on a difference between a step operation and a scan operation of the stage.

It is preferable that the gain of the board control system is increased when the stage performs the step operation.

The feedforward control system may be turned off when the stage performs a step operation.

[0034]

When a feedforward control system is provided for feeding a target value of a stage control system, such as a target moving speed of a stage, to a board control system in a feedforward manner in order to prevent pitching due to movement of the center of gravity, a step movement in which the moving distance of the stage is short. In the case of, for example, the base plate is shaken conversely. Therefore, an adjusting means is provided for adjusting the control function of the feedforward control system by changing, for example, the gain of the board control system based on the target value of the stage control system.

That is, by increasing the gain of the board control system when performing the step movement, the board is prevented from swinging due to the feedforward control.

Instead of changing the gain of the feedforward control system, the swing of the base may be avoided by turning off the feedforward control system when performing the step movement.

During the scanning operation, the center of gravity of the base plate is corrected by utilizing the feedforward control system, and pitching and the like can be prevented.

In this manner, by improving the vibration damping performance in the step operation and the vibration elimination performance in the scanning operation, both the transfer accuracy and the productivity of the exposure apparatus can be improved.

[0039]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 1 shows a first embodiment, which is a wafer or the like, which is a substrate to be exposed to which an original pattern such as a mask is transferred by exposure light generated from a light source as exposure means (not shown). A stage 1 for holding a substrate is provided.

The stage 1 performs a scanning operation for scanning the substrate together with the original during the exposure, and a step operation for changing the exposure area of the substrate.

An anti-vibration table 1 which is a table supporting the stage 1
0 is provided with air spring type support legs 11a and 11b,
These are air springs 12 which are actuators, respectively.
a and 12b, servo valves 13a and 13b for supplying and exhausting the air of the working fluid to both, and a position sensor 14 for measuring the vertical displacement of the vibration isolation table 10 at the measurement points.
a, 14b, mechanical springs 15a, 15b for preload, viscous elements 16a, 16b expressing the inherent viscosities of the air spring-type support legs 11a, 11b including the air springs 12a, 12b and the mechanical springs 15a, 15b for preload, respectively. It has acceleration sensors 17a and 17b.

A stage control system for controlling the position of the stage 1 moving in the X and Y directions on the vibration isolation table 10 includes a position sensor 2 for measuring the horizontal displacement of the stage 1, a motor 3 for driving the stage 1, and a stage displacement. It comprises a displacement amplifier 4 for amplification, a PID compensator 5, an amplifier 6, a target speed generator 7 for generating a target speed as a target moving speed of the stage 1, and an integrator 8.

The control system of the air spring type support legs 11a, 11b, which is a base control system, includes displacement amplifiers 21a, 21a.
b, displacement decomposer 22, PI compensators 23a and 23b, filters 24a and 24b, acceleration decomposer 25, thrust distributor 2
6, a target position setting unit 28 that generates a target position that is a target movement position of the amplifiers 27a and 27b and the anti-vibration table 10,
Further, a feedforward control system having a filter 29 having a predetermined appropriate gain and time constant is provided between the stage control system.

Next, the operation of the above-described air spring type vibration damping device will be described. The outputs of the acceleration sensors 17a and 17b are output from a filter 24 having a predetermined appropriate gain and time constant, respectively.
a and 24b are input to the acceleration decomposer 25.
Here, the two inputs are obtained by calculating the vertical acceleration of the anti-vibration table 10 by a 2 × 2 matrix operation, and the angle around an axis passing through the center of gravity of the anti-vibration table 10 and perpendicular to the operating direction of the stage 1 in the horizontal plane. It is decomposed into acceleration and is fed back negatively to the preceding stage of the thrust distributor 26. Damping is added by this acceleration feedback loop.

The outputs of the position sensors 14a and 14b pass through displacement amplifiers 21a and 21b, respectively, and are supplied to a displacement decomposer 22.
Input. Here, the vertical (Z-axis) displacement of the vibration isolation table 10 and the movement direction of the stage 1 (Y-axis direction) passing through the center of gravity of the vibration isolation table 10 are perpendicular to the horizontal plane by a 2 × 2 matrix operation. Decomposed into rotational displacements around a large axis (around the X axis). The target position setting device 28 sets the target positions of the vertical displacement and the rotational displacement, and a deviation signal between the output of the displacement decomposer 22 and the input of the thrust distributor 26 through the PI compensators 23a and 23b. . Here, the thrust target values in the vertical direction and in the rotation direction about the axis passing through the center of gravity of the vibration isolation table 10 and perpendicular to the operation direction of the stage 1 in the horizontal plane are calculated by the 2 × 2 matrix operation using the air spring 12a. 12b. The distributed drive target values are supplied to the servo valves 13a and 13b by amplifiers 27a and 27b, respectively.
b to the drive current of the servo valves 13a, 13b
The pressure in the air springs 12a and 12b is adjusted by the opening and closing of the valve, so that the anti-vibration table 10 can hold the desired position and posture set by the target position setting device 28 without a steady deviation.

Here, P of the PI compensators 23a and 23b means proportional, and I means integral operation. PI compensator 2
3a operates as a control compensator for the vertical displacement of the vibration isolation table 10, and the PI compensator 23b operates as a control compensator for the rotational displacement of the vibration isolation table 10.

Further, the output of the position sensor 2 passes through the displacement amplifier 4, and the deviation from the target position signal generated by the integrator 8 is input to the PID compensator 5. The output of the PID compensator 5 drives the stage 1 via the motor 6 through the amplifier 6.

Here, P of the PID compensator 5 means proportional, I means integral, and D means differential operation.

The target speed generator 7 generates the target speed of the stage 1 based on the operation profile generated by the stage sequence controller 30. The target speed of the stage 1 is integrated by the integrator 8 to become the target position of the stage 1. Further, the target speed of the stage 1 is fed through a feed forward control system having a filter 29 to a rotational displacement control system for correcting the center of gravity for preventing pitching of the vibration isolation table 10.

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
It is generally known that it can be approximated as the integral characteristic represented by the above equation (1).

The target speed fed forward to the rotational displacement control system of the vibration isolation table 10 is determined by the air springs 12a and 12a.
Since the integration is performed by the integration characteristic of b, feedforward of the target speed is equivalent to applying a rotational torque proportional to the position of the stage 1 to the vibration isolation table 10. By the feedforward input of the target speed, the rotational moment generated by the movement of the stage 1 can be canceled.

By such feed-forward control, the anti-vibration table 1 caused by the movement of the center of gravity accompanying the drive of the stage.
The fluctuation (pitching) of 0 can be effectively suppressed.

The stage sequence controller 30 determines the next target position while monitoring the current position of the stage 1. A target speed generator 7 based on the final target position and the current position of the stage 1 generated by the stage sequence controller 30
Performs the generation of the target speed for stage 1.

The gain setting device 31, which is an adjusting means, is
Of stage 1 generated by the sequence controller 30
By comparing the target position with the position at the start of the movement of the stage 1,
According to the target moving distance, which is the target value of stage 1,
Change the proportional gain of the PI compensator 23b of the rolling displacement control system
To adjust the control function. For example, as shown in FIG.
The target travel distance is S_NWhen smaller, the gain is k_N
And the target travel distance is S _FWhen it is larger, the gain is k_FTo
Then S_NAnd S_FK in the middle of_NAnd k_FTo graph A
Interpolate by linear interpolation or other functions as shown
You.

[0056] Gradient like graph A in FIG. 2 (a) are those determined by the response frequency of the air spring 12a, 12b, the difference in slower response proportional gain k _N and k _F increases.

If the moving distance of the stage 1 is very short compared to its moving range in a step operation without exposure or the like, the response speed of the air springs 12a and 12b, that is, the pressure change speed is lower than the moving speed of the stage 1. To
Feedforward control for the purpose of correcting the center of gravity of the vibration isolation table may cause the vibration isolation table 10 to swing instead.
In order to prevent such troubles and improve the performance of the vibration isolator, a gain setting unit 31 is provided which changes the proportional gain of the above-mentioned rotational displacement control system in accordance with the stage moving distance.

As described above, the stage 1 is a step-and-scan type semiconductor that performs exposure while repeating two operations of a scanning operation during exposure and a step operation of moving a wafer as a substrate without performing exposure. When the stage is an XY stage mounted on an exposure apparatus, the stage sequence controller 30 causes the stage 1 to perform a step operation and a scan operation based on a predetermined operation pattern.

[0059] When the scan operation, the proportional gain of the PI compensator 23b of the rotation control system for a large target moving distance of the stage 1 a constant value k _F. For the step-operation, to change the proportional gain of the PI compensator 23b of the rotation control system to a large value k _N.

As described above, the gain of the control system of the air springs 12a and 12b is changed in accordance with the response frequency, the moving distance and the moving speed of the stage 1, so that the vibration damping performance is enhanced during the stepping operation and the exposure waits. It is possible to shorten the time, improve the anti-vibration performance during the scanning operation, and improve the transfer accuracy.

The actuator for driving the anti-vibration table is not limited to an air spring, and any actuator such as a linear motor, a voice coil motor, and a piezoelectric element may be used.

Although the number of supporting legs for supporting the vibration isolation table is two in the vertical direction, the number of supporting legs may be three or more. When there are three support legs in the vertical direction, the control system of the anti-vibration table
In terms of a rectangular coordinate system, three control systems are configured: a translation control system in the Z-axis direction, a rotational displacement control system around the X-axis, and a rotational displacement control system around the Y-axis. In this case, the displacement decomposer, the acceleration decomposer, and the thrust distributor each perform a 3 × 3 matrix calculation. For example, when the operation direction of the stage is the Y-axis direction,
The output of the target speed generator of the stage is fed forward to a rotational displacement control system around the X axis of the vibration isolation table.

In the case of a stage that moves two-dimensionally on a plane such as an XY stage and has three support legs in the vertical direction, the X-axis target speed of the XY stage is adjusted around the Y-axis of the air spring type vibration isolator. The Y-axis target speed of the XY stage is fed-forward input to the rotational displacement control system to the rotational displacement control system around the X-axis of the air spring type vibration isolator. Thus, the rotational moment due to the movement of the center of gravity due to the plane movement of the XY stage can be canceled.

Further, the air spring supporting the vibration isolation table may be mounted not only vertically but also horizontally. By providing the air spring in the horizontal direction, the vibration of the vibration isolation table in the horizontal direction can be suppressed.

The gain of the control system of the air spring is as follows.
You can also decide. Target travel distance, maximum speed, maximum
When the large acceleration is determined, the trapezoidal speed pattern shown in FIG.
And the frequency spectrum of the target acceleration is
It can be calculated as shown in (b). This frequency
Figure 2 shows the gain for frequencies where the spectrum has a peak.
(C). Here, the rotational displacement control system
Servo band frequency is f _NAnd f_FF_N
And f_FIs determined. By determining the gain in this way,
To prevent the effect of air spring response delay.
You.

FIG. 3 shows a second embodiment. As in the first embodiment, an original pattern such as a mask is transferred by exposure light generated from a light source (not shown) as exposure means. A stage 41 for holding a substrate such as a wafer is provided.

The stage 41 performs a scanning operation for scanning the substrate together with the original during the exposure, and a step operation for changing the exposure area.

The anti-vibration table 50 supporting the stage 41 is provided with air spring type support legs 51a and 51b, which supply and exhaust air of the working fluid to the air springs 52a and 52b, respectively. Servo valves 53a, 5
3b, position sensors 54a and 54b for measuring vertical displacement of the vibration isolation table 50 at the measurement points, and a mechanical spring 5 for preload.
5a, 55b, air spring-type support legs 51a including the air springs 52a, 52b and mechanical springs 55a, 55b for preload,
Viscosity element 56 that expresses the inherent viscosity of 51b
a, 56b and acceleration sensors 57a, 57b.

The stage control system for controlling the position of the stage 41 moving in the X and Y directions on the anti-vibration table 50 includes a stage 4
1, a position sensor 42 for measuring the horizontal displacement, a motor 43 for driving the stage 41, a displacement amplifier 44 for amplifying the stage displacement, a PID compensator 45, an amplifier 46, and a target speed generator 47 for generating a target speed for the stage 41. , An integrator 48.

The control system of the air spring type support legs 51a, 51b, which is a platform control system, includes displacement amplifiers 61a, 61b.
b, displacement decomposer 62, PI compensators 63a, 63b, filters 64a, 64b, acceleration decomposer 65, thrust distributor 6
6. A feed having amplifiers 67a and 67b, a target position setting device 68 for generating a target position of the vibration isolation table 60, and a filter 69 having a predetermined appropriate gain and time constant between the stage control system and the stage. A forward control system is provided.

Next, the operation of the air spring type vibration damping device will be described. The outputs of the acceleration sensors 57a and 57b are supplied to a filter 64 having a predetermined appropriate gain and time constant, respectively.
a and 64b are input to the acceleration decomposer 65.
Here, the two inputs are obtained by a 2 × 2 matrix operation to calculate the vertical acceleration of the vibration isolation table 50 and the angle around an axis passing through the center of gravity of the vibration isolation table 50 and perpendicular to the operating direction of the stage 41 in the horizontal plane. It is decomposed into acceleration and is fed back negatively to the preceding stage of the thrust distributor 66. Damping is added by this acceleration feedback loop.

The outputs of the position sensors 54a and 54b pass through displacement amplifiers 61a and 61b, respectively, and output to the displacement decomposer 62.
Input. Here, the vertical (Z-axis) displacement of the vibration isolation table 50 and the movement direction of the stage 41 (Y-axis direction) passing through the center of gravity of the vibration isolation table 50 are perpendicular to the horizontal plane by a 2 × 2 matrix operation. Decomposed into rotational displacements around a large axis (around the X axis). The target position setter 68 sets the target positions of the vertical displacement and the rotational displacement, and a deviation signal between the output of the displacement decomposer 62 and the input of the thrust distributor 66 through the PI compensators 63a and 63b. . Here, by the 2 × 2 matrix operation, the thrust target values in the vertical direction and in the rotation direction about the axis passing through the center of gravity of the vibration isolation table 50 and perpendicular to the operation direction of the stage 41 in the horizontal plane are determined by the air springs 52a, 52b. The distributed drive target values are respectively supplied to the servo valves 53a, 53a by the amplifiers 67a, 67b.
The drive current of the servo valves 53a, 53b
The pressure in the air springs 52a and 52b is adjusted by opening and closing the valve 3b, and the vibration isolation table 50 can maintain the desired position and posture set by the target position setting device 68 without a steady-state deviation.

Here, P of the PI compensators 63a and 63b means proportional, and I means integral operation. PI compensator 6
3a operates as a control compensator for the vertical displacement of the vibration isolation table 50, and the PI compensator 63b operates as a control compensator for the rotational displacement of the vibration isolation table 50.

Further, the output of the position sensor 42 passes through the displacement amplifier 44, and the deviation from the target position signal generated by the integrator 48 is input to the PID compensator 45. The output of the PID compensator 45 drives the stage 41 via the motor 43 through the amplifier 46.

Here, P of the PID compensator 45 is proportional,
Represents integration, and D represents differentiation.

The target speed generator 47 generates a target speed of the stage 41 based on the operation profile generated by the stage sequence controller 70. The target speed of the stage 41 is integrated by the integrator 48 to become the target position of the stage 41. Further, the target speed of the stage 41 is
Is fed-forward input to the rotational displacement control system through a feed-forward control system having

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
It is generally known that it can be approximated as the integral characteristic represented by the above equation (1).

The target speed fed forward to the rotational displacement control system of the vibration isolation table 50 is determined by the air springs 52a and 52a.
Since the integration is performed by the integration characteristic of b, feed-forward of the target speed is equivalent to applying a rotational torque proportional to the position of the stage 51 to the vibration isolation table 50. By the feedforward input of this target speed, the stage 5
The pitching can be prevented by canceling out the rotational moment generated by the movement of the motor 1.

In this manner, the vibration of the vibration damping table 50 due to the movement of the center of gravity accompanying the driving of the stage can be effectively suppressed.

The stage sequence controller 70 determines the next target position while monitoring the current position of the stage 41. The target speed generator 47 generates a target speed of the stage 41 based on the final target position and the current position of the stage 41 generated by the stage sequence controller 70.

ON / OF together with a switch 72 described later
The stage operation determination means 71 constituting the F control means compares the final target position of the stage 41 generated by the stage sequence controller 70 with the position at the start of movement of the stage 41, and determines that the target movement distance of the stage 41 is a predetermined movement distance. When the value is larger than the value, the switch 72 provided in the feedforward control system is turned ON, and the target speed of the stage 41 is fedforward input to the PI compensator 63b of the rotational displacement control system. Conversely, when the target moving distance of the stage 41 is smaller than the predetermined value, the switch 72 is turned off, and the feedforward input of the target moving distance of the stage 41 is not performed.

The value of the target moving distance as a criterion for the ON / OFF control is determined by the response frequency of the air springs 52a and 52b, and increases as the response becomes slower.

That is, if the moving distance of the stage in the step operation without exposure is very short compared to its moving range, the response speed of the air spring, that is, the pressure change speed is slower than the moving speed of the stage. Since the feed-forward control for correcting the center of gravity of the shaking table may shake the anti-vibration table instead, the feed-forward control system is turned off.

As described above, the stage 41 is of a step-and-scan type in which exposure is performed while repeating two operations of a scanning operation during exposure and a step operation of moving a wafer which is a substrate to be exposed without performing exposure. A stage sequence controller 7 mounted on a semiconductor exposure apparatus
0 causes the stage 41 to perform a step operation and a scan operation based on a predetermined operation pattern.

In the case of the scanning operation, the feedforward control is performed because the target moving distance of the stage 41 is large. In the case of the step operation, the switch 72 is turned off.

In this manner, during the step operation, the vibration suppression performance can be enhanced to shorten the exposure standby time, and during the scanning operation, the vibration isolation performance can be enhanced to improve the transfer accuracy.

The actuator for driving the anti-vibration table is not limited to an air spring, and any actuator such as a linear motor, a voice coil motor, and a piezoelectric element may be used.

Although the number of supporting legs for supporting the vibration isolation table is two in the vertical direction, the number of supporting legs may be three or more. When there are three supporting legs in the vertical direction, the position control system of the anti-vibration table can be represented by a rectangular coordinate system, a Z-axis translation control system, a rotational displacement control system around the X axis, and a rotation around the Y axis. 3 of displacement control system
Configure two control systems. 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 output of the target speed generator of the stage is fed forward to the rotation control system around the X-axis of the vibration isolation table.

If the stage is a two-dimensionally movable stage such as an XY stage and has three support legs in the vertical direction, the X-axis target speed of the XY stage is adjusted around the Y-axis of the air spring type vibration isolator. The Y-axis target speed of the XY stage is fed-forward input to the rotational displacement control system to the rotational displacement control system around the X-axis of the air spring type vibration isolator. Thus, the rotational moment due to the movement of the center of gravity due to the plane movement of the XY stage can be canceled.

Further, the air spring supporting the vibration isolation table may be mounted not only vertically but also horizontally. By providing the air spring in the horizontal direction, the vibration of the vibration isolation table in the horizontal direction can be suppressed.

Next, an embodiment of a device manufacturing method using the above-described exposure apparatus will be described. FIG. 4 shows a manufacturing flow of a semiconductor device (a semiconductor chip such as an IC or an LSI, or a liquid crystal panel or a CCD). In step 1 (circuit design), the circuit of the semiconductor device is designed. Step 2 is a process for making a mask on the basis of the circuit pattern designed. In step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon.
Step 4 (wafer process) is called a pre-process, and an actual circuit is formed on the wafer by lithography using the prepared mask and wafer. Step 5
(Assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in Step 4, and includes processes such as an assembly process (dicing and bonding) and a packaging process (chip encapsulation). In step 6 (inspection), inspections such as an operation confirmation test and a durability test of the semiconductor device manufactured in step 5 are performed. Through these steps, a semiconductor device is completed and shipped (step 7).

FIG. 5 shows a detailed flow of the wafer process. Step 11 (oxidation) oxidizes the wafer's surface. Step 12 (CVD) forms an insulating film on the wafer surface. Step 13 (electrode formation) forms electrodes on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted into the wafer. Step 15
In (resist processing), a photosensitive agent is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus to print and expose the circuit pattern of the mask onto the wafer. Step 17 (development) develops the exposed wafer. In step 18 (etching), portions other than the developed resist image are removed. In step 19 (resist stripping), unnecessary resist after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. By using the manufacturing method of this embodiment, it is possible to manufacture a highly integrated semiconductor device, which has been conventionally difficult to manufacture.

[0093]

Since the present invention is configured as described above, the following effects can be obtained.

By changing the gain of the position control of the anti-vibration table according to the target moving distance of the stage, or by turning off the feedforward control system, the anti-vibration table can be used due to the response delay of the actuator of the anti-vibration table. This can prevent the table from swinging.

In particular, in a step-and-scan type exposure apparatus in which a scanning operation during exposure and a step operation without exposure are repeated, both the damping performance during the step operation and the anti-vibration performance during the scanning operation are improved. Thus, an exposure apparatus with high productivity and high transfer accuracy can be realized.

The use of such an exposure apparatus can contribute to higher definition and lower cost of semiconductor devices and the like.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing a first embodiment.

FIG. 2 is a diagram illustrating a method of changing a gain of a control system.

FIG. 3 is a schematic diagram showing a second embodiment.

FIG. 4 is a flowchart showing a semiconductor manufacturing process.

FIG. 5 is a flowchart showing a wafer process.

FIG. 6 is a schematic diagram showing one conventional example.

FIG. 7 is a graph showing a relationship between a target speed, a target acceleration, and a target position of the stage.

[Explanation of symbols]

1, 41 stage 2, 14a, 14b, 42, 54a, 54b position sensor 3, 43 motor 7, 47 target speed generator 8, 48 integrator 10, 50 anti-vibration table 11a, 11b, 51a, 51b air spring type support Legs 12a, 12b, 52a, 52b Air springs 13a, 13b, 53a, 53b Servo valves 17a, 17b, 57a, 57b Acceleration sensors 23a, 23b, 63a, 63b PI compensators 28, 68 Target position setting devices 30, 70 Stage sequence Controller 31 Gain setting unit 71 Stage operation determination means 72 Switch

Claims (14)

[Claims] 1. A vibration isolation device comprising: a base, a stage moving on the base, a stage control system for controlling the position of the stage, and an actuator for maintaining the position and orientation of the base. A stage control device for controlling the actuator, and a feed-forward control system for feed-forward inputting a target value of the stage control system to the mount control system, a target moving distance and a target moving speed of the stage; And controlling a control function of the feedforward control system based on at least one of a response frequency of the actuator and a response frequency of the actuator. 2. A vibration isolation device comprising: a base, a stage moving on the base, a stage control system for controlling the position of the stage, and an actuator for maintaining the position and orientation of the base. A board control system for controlling the actuator, a feedforward control system for feedforward inputting a target value of the stage control system to the board control system, and the feedforward based on a target value of the stage control system. A stage device having an adjusting unit for adjusting a control function of a control system. 3. The stage apparatus according to claim 2, wherein the adjusting means is configured to change a gain of the board control system. 4. The stage apparatus according to claim 2, wherein the adjustment means is configured to perform ON / OFF control of a feedforward control system. 5. The stage device according to claim 2, wherein the actuator has an air spring. 6. The stage device according to claim 2, wherein the actuator has at least one of a linear motor, a voice coil motor, and a piezoelectric element. 7. The system according to claim 2, wherein the gain of the platform control system is increased when the target movement distance of the stage is smaller than a predetermined value. Stage equipment. 8. The stage according to claim 2, wherein the feedforward control system is turned off when the target movement distance of the stage is smaller than a predetermined value. apparatus. 9. The stage apparatus according to claim 2, wherein the feedforward control system is configured to control pitching of the base. 10. An exposure apparatus, comprising: the stage device according to claim 2; and an exposure unit configured to expose a substrate to be exposed held by the stage device. 11. An exposure apparatus of a step-and-scan method, comprising: a base, a stage moving on the base, a stage control system for controlling a position of the stage, and a stage held by the stage. Exposure means for exposing the substrate to be exposed, an anti-vibration device including an actuator for maintaining the position and orientation of the platform, a platform control system for controlling the actuator, and a target value of the stage control system. An exposure apparatus comprising: a feedforward control system for feedforward inputting to a board control system; and an adjusting unit for adjusting a control function of the feedforward control system based on a difference between a step operation and a scanning operation of the stage. 12. The exposure apparatus according to claim 11, wherein when the stage performs a step operation, the gain of the platform control system is increased. 13. The exposure apparatus according to claim 11, wherein the feedforward control system is turned off when the stage performs a step operation. 14. A device manufacturing method, wherein a wafer is exposed by the exposure apparatus according to claim 10.