JP2003232398A - Vibration damper and adjusting method therefor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To safely and easily execute adjustment of a floor vibration feed forward loop in the same manner as a feedback loop using a detecting signal of vibration of a vibration damper bed. <P>SOLUTION: A vibration damper has the vibration damper bed 1, an air spring 3 to support the vibration damper bed, a first acceleration sensor 4 to detect the vibration of the vibration damper bed, the feedback loop to control pressure of the air spring according to the detecting signal of the first acceleration sensor, a second acceleration sensor 5 to detect the vibration of a floor 2 on which the air spring is installed, and the feed forward loop to control the pressure of the air spring according to the detecting signal of the second acceleration sensor. A gain of the feed forward loop is set according to the setting of the gain of the feedback loop. <P>COPYRIGHT: (C)2003,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a vibration isolation device used in precision equipment such as a semiconductor exposure apparatus. More specifically, the present invention relates to an anti-vibration device of a type which is called an active type, in which vibration of a vibration isolation table and a floor is detected by a vibration detection means and an actuator is driven according to a detection signal.

[0002]

2. Description of the Related Art In precision instruments such as an electron microscope and a semiconductor exposure apparatus, it is necessary to cut off vibration transmission from the external environment to the apparatus as much as possible. Therefore, it is an essential requirement that these precision instruments be mounted on a vibration isolation device. Particularly in a semiconductor exposure apparatus, since the exposure XY stage moves continuously at high speed, the vibration isolation apparatus has high precision in both vibration isolation performance against external vibration and vibration isolation performance against internal vibration generated by the operation of the mounted device itself. Realization is required.

In response to such demands, in recent years, an active vibration isolator equipped with a vibration sensor and an actuator has been put into practical use. In the vibration isolator, effective vibration control is possible by driving the actuator according to the detection signal of the vibration sensor. On the other hand, the passive vibration isolator is composed only of the support mechanism having the spring and damper characteristics, and there is a trade-off between the vibration isolation performance and the vibration damping performance. In the passive vibration isolator, if the vibration isolation performance is prioritized, the support mechanism is required to have low rigidity and low viscosity, but this requirement deteriorates the vibration damping performance. The advantage of the active type vibration isolation device is that both vibration isolation performance and vibration control performance can be achieved. By driving the actuator according to the detection signal of the vibration sensor, effective vibration isolation and vibration suppression can be realized.

In the active type vibration isolation device, a vibration sensor is installed on a vibration isolation table equipped with precision equipment, and a detection signal of the vibration sensor is fed back to an actuator.
Then, the vibration of the floor on which the vibration isolation table itself is installed is detected, and this detection signal is fed forward to the actuator. The vibration isolation device disclosed in Japanese Patent Application Laid-Open No. 2000-274482 (active vibration isolation device, exposure apparatus and method, and device manufacturing method) has a skyhook viscosity (skyhook damper effect) and sky A feedback loop is used to add hook rigidity (skyhook spring effect). According to the publication, the vibration isolation device has an air spring actuator that supports the vibration isolation table and a vibration measurement unit that measures the vibration of the vibration isolation table. By supporting the vibration isolation table with a rigid element such as an air spring actuator, vibration transmission from the installation floor to the vibration isolation table is blocked. Further, it is provided with a feedback loop of acceleration and velocity, and the acceleration and velocity based on the output of the vibration measuring means are fed back to the air spring actuator to add the viscosity and rigidity of the skyhook to the vibration isolation table. Skyhook means that an absolute stationary point in space is used as a fulcrum, and the viscosity and rigidity of the skyhook have the effect of making the vibration isolation table absolutely stationary. Rigidity suppresses displacement, and viscosity has the effect of quickly damping residual vibration.

Further, the vibration isolator disclosed in Japanese Unexamined Patent Publication No. 2001-20996 (vibration isolator and semiconductor manufacturing equipment) drives an air spring actuator in accordance with a detection signal from a vibration sensor installed on the floor. Uses a feedforward loop. According to the publication, the vibration isolation device has an air spring that supports the vibration isolation table and a vibration measurement unit that measures the vibration of the installation floor. The vibration transmitted from the installation floor to the vibration isolation table is roughly damped by the air spring, but the vibration is not completely insulated. The vibration of the installation floor is transmitted to the vibration isolation table by using the air spring that is the supporting leg as a transmission path. The feedforward loop drives the air spring to cancel the vibration transmission of the installation floor. By feeding forward the vibration of the installation floor to the air spring, the vibration isolation table is vibrationally isolated from the installation floor.

The feedforward means that when a signal transmission path is displayed in a block diagram, the path is one-way to the controlled object. That is, the feedforward loop is an open loop.
In the floor vibration feedforward loop of the vibration isolator, the controlled object is the vibration isolation table and the signal source is the floor. The signal path is a one-way path in which vibration of the floor is detected, an air spring is driven according to the detection signal, and a vibration damping force is applied to the vibration isolation table. On the other hand, the feedback means that the signal transmission path includes a controlled object to form a closed loop. In a vibration isolator, skyhook viscosity and stiffness are typical feedback loop effects. The vibration detecting means detects the vibration of the vibration isolation table to be controlled, and after appropriately compensating the detected signal, the vibration damping force according to the compensating signal is applied to the vibration isolation table. Gives the skyhook viscosity and rigidity. In this way, the closed loop including the vibration isolation table is configured.

[0007]

Although feedforward is an effective control method, it has a problem that adjustment is difficult by trial and error. Although the theoretically optimum adjustment point is uniquely determined, there is a gap between the theoretical and numerical solution and the actual measurement result in the actual machine as a common sense in the industrial field.
The optimum adjustment state obtained by simulation is rarely used as the initial value when the control system is started up in the actual machine. This is because if an excessive signal is input to the actuator, the equipment will be damaged in the worst case. The momentum and adjustment of the feedforward loop is a trial-and-error operation in which the loop gain is set to a very small value as an initial value, the value is gradually increased, and the maximum point of the control effect is sought.

In the adjustment of the floor vibration feedforward loop, the vibration transfer characteristic from the floor to the vibration isolation table was measured, and the adjustment was confirmed when the transfer characteristic became minimum. However, it is expensive to measure the transfer characteristic.
It is necessary to measure vibration for a long time using an FT analyzer. What is FFT? Fast Fourier Tra
It is an abbreviation for nsform. As described above, the feed-forward loop for floor vibration requires a great deal of time, labor and cost for adjustment. Therefore, there are problems that the production process is enlarged, the production efficiency is deteriorated, and the production cost is increased.

As is known, the action of the feedforward loop is proactive, whereas the action of the feedback loop is reflexive. The feed-forward loop acts to cancel the disturbance before it is applied to the controlled object, so that when it works effectively, the disturbance input to the controlled object can be completely blocked. This is why it is said to be a proactive action. The feedback loop operates to suppress the fluctuation after detecting the fluctuation of the controlled object. It is said to be a reflexive action because it works to correct this after a problem occurs. The feedback loop cannot completely suppress the disturbance. As compared with the case where the feedback loop is not configured, the disturbance is suppressed only at a certain ratio.

However, the great advantage of the feedback loop lies in its ease of adjustment. Usually, the adjustment of the feedback loop is performed by measuring the loop transfer function of the loop before the closed loop is formed. By observing the open loop transfer function, it is possible to easily infer what the feedback loop will do when a closed loop is formed. Feedback control can be executed after the optimum adjustment state is determined. Therefore, an unsuitable and excessive signal is not input to the actuator, and safe and reliable control system adjustment is performed. In addition, since adjustment is easy, it greatly contributes to improvement in production efficiency. In the vibration isolator, the viscosity of the skyhook and the rigidity of the skyhook are safely and easily realized by the feedback loop.

The present invention has been made in consideration of such circumstances. That is, the object of the present invention is to provide a method and a vibration isolation device in which the adjustment of the floor vibration feedforward loop is performed safely and easily, similarly to the feedback loop using the detection signal of the vibration of the vibration isolation table. That is.

[0012]

In order to achieve the above object, the adjusting method of the present invention detects a vibration isolation table, an air spring supporting the vibration isolation table, and vibration of the vibration isolation table. A first acceleration sensor, a feedback loop that controls the pressure of the air spring according to a detection signal of the first acceleration sensor, and a second acceleration sensor that detects vibration of the floor on which the air spring is installed. A feed-forward loop that controls the pressure of the air spring in accordance with a detection signal of the second acceleration sensor.
The method further comprises a first step of setting the gain of the feedback loop and a second step of setting the gain of the feedforward loop according to the setting of the gain of the feedback loop.

A vibration isolator to which the present invention is applied includes a vibration isolation table, an air spring supporting the vibration isolation table, a first acceleration sensor for detecting vibration of the vibration isolation table, and a first acceleration sensor. A feedback loop that controls the pressure of the air spring according to the detection signal, and a second loop that detects the vibration of the floor on which the air spring is installed.
And the feedforward loop that controls the pressure of the air spring according to the detection signal of the second acceleration sensor.

According to the vibration isolator, the vibration isolation table on which precision equipment such as an exposure XY stage is mounted is supported by an air spring. The first acceleration sensor is attached to the vibration isolation table and detects the vibration of the vibration isolation table as an acceleration signal.
The feedback loop is configured to control the pressure of the air spring in response to the detection signal of the first acceleration sensor.
The feedback loop acts to suppress the vibration of the vibration isolation table. The second acceleration sensor is attached to the floor on which the air spring is installed, and detects the vibration of the floor as an acceleration signal. The feedforward loop is configured to control the pressure of the air spring in response to the detection signal of the second acceleration sensor. The feedforward loop acts to cancel the vibration transmitted from the floor to the vibration isolation table by using the air spring as a transmission path.

According to the adjusting method of the present invention, the gain of the feedback loop can be set in the first step by a known method. The feature of the present invention resides in the second step. That is, in the second step of the present invention, the setting of the gain of the feedforward loop is performed according to the setting of the gain of the feedback loop in the first step. Therefore, the feedforward loop operates safely and reliably.

The gain of the feedforward loop obtained as the optimum adjustment point by the conventional theory has a problem such as equipment damage due to excessive input when the vibration isolator is operated by suddenly setting it. Therefore, the adjustment of the feedforward loop is usually performed by trial and error, such as setting the loop gain to a very small initial value and gradually increasing the gain while checking the control effect. It was However, in the present invention, the feedforward loop can be adjusted according to the setting of the feedback loop. No trial and error adjustments are necessary. Therefore,
It is possible to significantly improve the production efficiency of the vibration isolation device.
In addition, F for vibration measurement that was used for adjustment
No expensive equipment such as an FT analyzer is required.

Further, in a preferred embodiment of the present invention, the feedback loop is a feedback loop which imparts rigidity to the vibration isolation table, and in the second step,
The feed-forward loop loop transfer function is used to set the gain of the feed-forward loop.

The feedback loop acts to add rigidity to the vibration isolation table. At this time, the open loop transfer function of the feedback loop is a transfer function from an external force acting on the vibration isolation table to the displacement of the vibration isolation table, and coincides with a response generally called compliance. In the compliance response, the gain in the lower range than the resonance frequency determined by the inertia of the vibration isolation table and the rigidity of the air spring is equal to the reciprocal of the rigidity of the air spring.
On the other hand, the transmission of the floor vibration to the vibration isolation table is due to the rigidity of the air spring that is the supporting leg. The gain of the feedforward loop is set using the low-frequency gain of the open loop transfer function.
Therefore, the feedforward loop operates properly without any trial and error adjustment.

In another preferred embodiment of the present invention, the feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and in the second step, the rigidity of the vibration isolation device is doubled. The gain setting of the feedback loop and the gain setting of the feedforward loop are matched.

When the vibration isolator is analyzed dynamically, the setting of the gain of the feedback loop that doubles the rigidity of the vibration isolator matches the setting of the gain of the feedforward loop that cancels the floor vibration. Therefore, in the vibration isolation device adjusted by the adjustment method of the present invention, the feedforward loop operates properly.

A first vibration isolation device according to the present invention is a vibration isolation table, an air spring supporting the vibration isolation table, a first acceleration sensor for detecting vibration of the vibration isolation table, and the first vibration isolation device. A feedback loop for controlling the pressure of the air spring according to the detection signal of the acceleration sensor, a second acceleration sensor for detecting the vibration of the floor on which the air spring is installed, and a detection signal of the second acceleration sensor. A vibration isolation device having a feedforward loop for controlling the pressure of the air spring according to the above, wherein the feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and the gain of the feedback loop is the vibration isolation. It is characterized in that the rigidity imparted to the table is equivalently set to be twice the original rigidity of the air spring.

As described above, the setting of the gain of the feedback loop that doubles the rigidity of the vibration isolator dynamically matches the setting of the gain of the feedforward loop that cancels floor vibration. Therefore, in the first vibration isolator according to the present invention, the feedforward loop can be properly operated only by matching the gain setting of the feedforward loop with the gain setting of the feedback loop.

A second vibration isolation device according to the present invention includes a vibration isolation table, an air spring supporting the vibration isolation table, a first acceleration sensor for detecting vibration of the vibration isolation table, and the first vibration sensor. A feedback loop for controlling the pressure of the air spring according to the detection signal of the acceleration sensor, a second acceleration sensor for detecting the vibration of the floor on which the air spring is installed, and a detection signal of the second acceleration sensor. A vibration isolation device having a feedforward loop that controls the pressure of the air spring in accordance with the feedback loop, wherein the feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and the stiffness applied to the vibration isolation table. Is equivalently set to twice the original stiffness of the air spring, and the gain setting of the feedback loop and the gain setting of the feedforward loop are matched. This vibration isolator can properly operate the feedforward loop for the above reason. After installation or when actually operating,
If the gain setting of the feedforward loop remains unchanged, the gain setting of the feedback loop may be changed.

The anti-vibration device adjusted by the adjusting method of the present invention or the anti-vibration device of the present invention is preferably used as an anti-vibration device provided in an exposure apparatus. In an exposure apparatus used for manufacturing a device having a fine pattern such as a semiconductor chip, a liquid crystal panel, and a thin film magnetic head, precision instruments such as an XY stage for exposure and a projection lens for exposure are mounted on a vibration isolation table. In the vibration isolation table, the floor vibration feedforward loop operates properly without trial and error adjustment. Therefore, it is possible to provide the semiconductor exposure apparatus in which the vibration transmission from the floor is blocked and the production efficiency is improved.

[0025]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of a vibration isolator according to the present invention will be described in detail with reference to the drawings. FIG. 1 shows a vibration isolation device according to an embodiment of the present invention. In the figure, a vibration isolation table 1 on which precision equipment such as an XY stage and an exposure projection lens is mounted has a triangular shape. Air springs 3a, 3b are provided near each vertex.
It is supported by 3c. The constituent elements with the subscript a on the left front of the drawing will be described below. The components having the subscripts b and c have the same configuration and operation as the components having the subscript a. In addition, in the component of the subscript c,
Air spring 3c, power amplifier 11c and air valve 12c
Are not shown.

The air spring 3a supports the vibration isolation table 1 from the floor 2. The air spring 3a is a supporting leg that supports the vibration isolation table 1, and at the same time, plays a role of an actuator that applies a damping force to the vibration isolation table 1. Damping force is generated by actively controlling the pressure. For this purpose, the air spring 3a is connected to the air valve 1
2a. The air valve 12a is a pressure control type air valve. The power amplifier 11a drives the air valve 12a. The pressure of the air spring 3a is controlled according to the input signal to the power amplifier 11a. Generally, air spring 3a, air valve 12
The pneumatic actuator that combines a and the power amplifier 11a generates a damping force by integrating with respect to the input signal to the power amplifier 11a. That is, the air spring 3a generates a thrust force according to the integrated value of the input signal to the power amplifier 11a.

The air spring 3a generates a thrust sufficient to support a large weight such as the vibration isolation table 1, and is therefore widely used as a support leg of the vibration isolation device. Further, the actuator for actively controlling the vibration is characterized by having integral characteristics.

The vibration isolation table 1 has a first acceleration sensor 4a near the portion supported by the air spring 3a. The first acceleration sensor 4a outputs the vibration generated in the vibration isolation table 1 as an acceleration signal. The second acceleration sensor 5a is attached near the air spring 3a on the floor 2 on which the air spring 3a is installed. The second acceleration sensor 5a outputs the vibration of the floor 2 as an acceleration signal. First
As the acceleration sensor 4a and the second acceleration sensor 5a, it is desirable to adopt a servo type acceleration sensor in terms of accuracy and resolution.

The controller 6a is the first acceleration sensor 4
An input signal to be supplied to the power amplifier 11a is generated according to the output of a and the second acceleration sensor 5a. Controller 6
The air spring 3a imparts an appropriate damping force to the vibration isolation table 1 by the action of a.

The operation of the controllers 6a, 6b and 6c will be described in more detail. FIG. 2 is an embodiment in which, in the vibration isolation device shown in FIG. 1, only the components near one apex of the vibration isolation table 1 are taken out and the configuration of the controller 6 is illustrated in detail. In FIG. 1, each constituent element distinguished by the subscripts a, b, and c corresponds to the embodiment of FIG. In FIG. 2, subscripts a, b, and c are omitted to simplify the notation.

The vibration isolation table 1 is supported from the floor 2 by an air spring 3. The air spring 3 is a support leg that supports the vibration isolation table 1, and at the same time, plays a role of an actuator that applies a damping force to the vibration isolation table 1. The air valve 12 controls the pressure of the air spring 3. The power amplifier 11 drives the air valve 12 according to the input signal. The first acceleration sensor 4 is installed on the vibration isolation table 1 and detects the vibration of the vibration isolation table 1 as an acceleration signal. The second acceleration sensor 5 is installed on the floor 2 and detects the vibration of the floor 2 as an acceleration signal. The controller 6 generates an input signal to be given to the power amplifier 11 according to the detection signal of the first acceleration sensor 4 and the detection signal of the second acceleration sensor 5. The air spring 3 applies an appropriate vibration damping force to the vibration isolation table 1 by the action of the controller 6. The controller 6 includes an integrator 7, a floor vibration gain 8, a rigidity gain 9, and a viscosity gain 10.

The pneumatic actuator consisting of the power amplifier 11, the air valve 12, and the air spring 3 is
A damping force is applied to the vibration isolation table 1 by integration with respect to an input signal to the vibration isolation table 1. The loop including the viscosity gain 10 is a feedback loop in which the viscosity gain 10 is applied to the detection signal of the first acceleration sensor 4 and is given to the power amplifier 11 as an input signal. By the action of the feedback loop,
A vibration damping force proportional to the speed is applied to the vibration isolation table 1. This is equivalent to giving viscosity to the vibration isolation table 1. The vibration generated on the vibration isolation table 1 by viscous application is quickly attenuated.

The feedback loop in this case means that the signal path including the vibration isolation table 1 to be controlled constitutes a closed loop. Since the vibration of the vibration isolation table 1 is detected by the first acceleration sensor 4 and the damping force according to the detection signal is applied to the vibration isolation table 1, a closed loop is formed. The viscous feedback loop is an essential component in an active vibration isolation system.

The loop including the rigidity gain 9 is a loop for imparting rigidity to the vibration isolation table 1. The acceleration of the vibration isolation table 1 detected by the first acceleration sensor 4 is introduced into the integrator 71 and converted into a velocity signal. The speed signal of the vibration isolation table 1 is input to the power amplifier 11 after being subjected to appropriate gain compensation by the rigidity gain 9. Since the actuator has the integral characteristic as described above, the vibration damping force proportional to the displacement of the vibration isolation table 1 is applied to the vibration isolation table 1 by the action of the feedback loop including the rigidity gain 9. This is a vibration isolation table 1
It is equivalent to giving rigidity to. By imparting rigidity, the vibration suppressing performance of the vibration isolator is improved especially in the low frequency band.

The loop including the floor vibration gain 8 is the air spring 3
Is a feed-forward loop for canceling the vibration transmitted from the floor 2 to the vibration isolation table 1 by using the transmission path as the transmission path. The acceleration signal of the floor 2 detected by the second acceleration sensor 5 is introduced into the integrator 72 and converted into a velocity signal. The velocity signal of the floor 2 is input to the power amplifier 11 after being appropriately gain-compensated by the floor vibration gain 8. Since the actuator has the integral characteristic, the vibration damping force proportional to the displacement of the floor 2 is applied to the vibration isolation table 1 by the action of the feedforward loop including the floor vibration gain 8. This cancels out the floor vibration transmission using the air spring 3 as a transmission path. This is because the floor vibration is transmitted mainly due to the rigidity of the air spring 3. That is, the disturbance force proportional to the displacement of the floor 2 is applied to the vibration isolation table 1
Act on. The feedforward loop including the floor vibration gain 8 acts to cancel this disturbance force. Therefore, the vibration isolation table 1 is completely vibration-insulated with respect to the floor 2.

The feed-forward loop in this case means that the signal path including the vibration isolation table 1 to be controlled is one-way and does not form a closed loop. The vibration of the floor 2 is detected by the second acceleration sensor 5,
Since the damping force according to the detection signal is applied to the vibration isolation table 1,
The signal path is one-way from the floor 2 to the vibration isolation table 1.

The value of the floor vibration gain 8 is uniquely determined. However, conventionally, it was not easy to search for the optimum value at the industrial site. According to the conventional method, the value of the floor vibration gain 8 is initially set to be sufficiently small. Next, the value of the floor vibration gain 8 is gradually increased while confirming the vibration transfer characteristic from the floor 2 to the vibration isolation table 1. Then, the floor vibration gain 8 is determined in a state where the vibration transfer characteristic is minimized. The adjustment of the floor vibration gain 8 was complicated and trial and error.

The essence of the present embodiment is that the loop transfer function of the stiffness-providing feedback loop is used for adjusting the floor vibration feedforward loop. The open loop transfer function of the feedback loop can be easily measured before closing the loop. This greatly simplifies the adjustment of the floor vibration feedforward loop.

The essence of this embodiment will be described with reference to mathematical expressions and block diagrams of signal transmission paths. FIG. 3 is a drawing in which the vibration isolation table 1, the floor 2 and the air spring 3 are dynamically modeled. The vibration isolation table 1 is a rigid body having a mass M. The air spring 3 is a stiffness element of stiffness K and a viscous element of viscosity D. The damping force actively generated by the air spring 13 by the air valve 12 is
Expressed as force F. Then, the transfer function from the force F and the displacement X _{0 of the} floor to the displacement X of the vibration isolation table is shown by the following equation. (Ms ² + Ds + K) X = (Ds + K) X ₀ + F (1)

In the equation (1), the symbol s is a Laplace operation.
Is a child. X on the right side of the equation (1) ₀Related to (Ds +
K) shows the vibration transmission path from the floor 2 to the vibration isolation table 1.
And is equal to the sum of the stiffness K and the viscosity D of the air spring.

Here, the magnitude relationship between Ds and K, which are vibration transmission paths, will be considered. Ds is a function of frequency,
The magnitude is infinitesimal at low frequencies and the magnitude is infinite at high frequencies. On the other hand, K is constant regardless of frequency. Usually, the frequency of concern in the vibration isolator is a relatively low frequency, and Ds is negligibly smaller than K in this frequency band. Therefore, Ds can be deleted from (Ds + K) on the right side of Expression (1). At this time, the equation (1) is simplified as the following equation. (Ms ² + Ds + K) X = KX ₀ + F (2)

FIG. 4 is a block diagram of signal transfer in which the transfer function represented by the equation (2) and the feedback loop and feedforward loop shown in FIG. 2 are combined. The block G _a / s shows the integral characteristic from the input signal to the power amplifier 11 to the damping force generated by the air spring 3. Since the vibrations of the vibration isolation table 1 and the floor 2 are detected as acceleration signals, blocks s ² (acceleration sensors 4, 5) act on the displacement X of the vibration isolation table 1 and the displacement X _{0 of the} floor 2, respectively. s ² X indicates the acceleration of the vibration isolation table 1, and s ² X ₀ indicates the acceleration of the floor 2.

The block G _d shows the gain of the viscous gain 10. A feedback loop is configured in which the viscous gain G _d is applied to the acceleration s ² X of the vibration isolation table 1 and then negatively fed back to the air spring 3. Viscosity is applied to the vibration isolation table 1 by the action of the feedback. The vibration generated on the vibration isolation table 1 is quickly attenuated by viscous application.

Block 1 / s shows integrators 71 and 72. The block G _k indicates the gain of the rigidity gain 9. A feedback loop is configured in which the integrator 1 / s and the rigidity gain G _k are applied to the acceleration s ² X of the vibration isolation table 1 in a cascade manner, and then negatively fed back to the air spring 3. The effect of the feedback gives rigidity to the vibration isolation table 1. By imparting rigidity, vibration of the vibration isolation table 1 is mainly suppressed in the low frequency band.

In floor vibration transmission using the air spring 3 as a transmission path, the displacement X _{0 of the} floor 2 is a dynamic characteristic of the vibration isolation table 1 via the rigidity K of the air spring 3 and is a block 1 / (Ms ² + Ds + K).
It is shown with the path to enter into. It is the floor vibration feedforward loop that acts to cancel this transmission path. The same loop is shown by the loop including the block G _f . The block G _f is the gain of the floor vibration gain 8.
A forward loop is formed in which the integrator 72 is acted on the acceleration s ² X ₀ of the floor 2 to convert it into a velocity signal, and then the floor vibration gain G _f is acted on and input to the air spring 3. In order to cancel the floor vibration transmission, the floor vibration feedforward loop is compared with the floor vibration transmission path in FIG.
The following formula must hold. K−s ² (1 / s) G _f (G _a / s) = 0 (3)

At this time, the floor vibration gain G _f is uniquely determined by the following equation. G _f = K / G _a (4) If the floor vibration gain G _f satisfies the equation (4), the floor vibration feedforward loop properly operates to isolate the vibration isolation table 1 from the floor 2 by vibration.

However, it is not easy to actually set the floor vibration gain G _f so as to satisfy the equation (4). Momentum and adjustment will be trial and error. First, the floor vibration gain G _f is set to be sufficiently small as an initial value. Next, the value of the floor vibration gain G _{f is} gradually increased while confirming the vibration transfer characteristic from the floor 2 to the vibration isolation table 1. Then, when the vibration transfer characteristic becomes the minimum, the floor vibration gain G _f is determined. To measure the vibration transfer characteristic, it is necessary to measure the vibration for a long time using a measuring device such as an FFT analyzer. As described above, conventionally, the adjustment of the floor vibration gain G _f has been complicated and trial and error.

On the other hand, the feedback loop is adjusted by measuring the loop transfer function of the loop, as is known. The open loop transfer function can be easily measured before closing the loop. There is no adjustment criterion corresponding to the open loop transfer function in the feedforward loop. Therefore, in the present embodiment, the loop transfer function of the stiffness-imparting feedback loop is used to adjust the floor vibration feedforward loop. The adjustment of the feedforward loop is greatly simplified by this.

In FIG. 4, focusing on the stiffness-providing feedback loop including the stiffness gain G _k , the _open loop transfer function G _open of the feedback loop is given by the following equation. G _open = G _k G _a / (Ms ² + Ds + K) (5)

The closed loop transfer function G _close of the feedback loop is given by the following equation. G _close = G _k G _a / (Ms ² + Ds + K + G _k G _a ) (6)

The gain diagram of the _open loop transfer function G _open is roughly as shown in FIG. 5 in the frequency domain. It is similar to the compliance response (displacement / force response) of the secondary resonance system.
At frequencies lower than the resonance frequency (K / M) ^1/2 determined by the mass M of the vibration isolation table 1 and the rigidity K of the air spring 3, the gain G _k G _a /
It is a flat characteristic of K. Further, it has a high frequency attenuation characteristic of -40 dB / decade in a frequency range higher than the resonance frequency. Now, assuming that the rigidity gain G _k is adjusted so that the gain of the flat portion of the low frequency becomes 0 dB, the following equation holds from FIG. G _k G _a / K = 1 (7)

At this time, the rigidity gain G _k is given by the following equation. G _k = K / G _a (8) Then, when the stiffness gain G _k defined by the equation (8) is substituted into the equation (6), the closed loop transfer function G _close is as shown by the following equation. G _close = K / (Ms ² + Ds + 2K) (9)

Comparing the _open loop transfer function G _open expressed by the equation (5) and the closed loop transfer function G _close expressed by the equation (8), the term indicating the rigidity acting on the vibration isolation table 1 is from K to 2K.
You can see that it has doubled. Due to the action of the feedback loop for imparting rigidity, the rigidity of the vibration isolator is doubled. As a result, the vibration suppression performance of the vibration isolation device is improved by a factor of 2 mainly in the low frequency band.

The floor vibration gain G _f is uniquely determined by the equation (4). On the other hand, the rigidity gain G _k was adjusted so as to double the rigidity of the vibration isolator as shown in equation (8). At this time, the floor vibration gain G _f coincides with the rigidity gain G _k , as is clear by comparing the equations (4) and (8). That is, the floor vibration gain G _f may be set to the same value as the rigidity gain G _k .

The gain adjustment of the floor vibration feedforward loop according to this embodiment will be summarized. First, the open loop transfer function of the stiffness-imparting feedback loop is measured. Next, in the open loop transfer function, the rigidity gain G _k is determined so that the gain at a frequency lower than the resonance frequency becomes 0 dB. Then, the floor vibration gain G _f is determined to be the same value as the rigidity gain G _k thus obtained. With the above, the floor vibration feedforward loop operates properly.

Of course, the floor vibration gain G _f
After determining, the stiffness gain G _k does not necessarily have to match the floor vibration gain G _f . The essence of this embodiment is to utilize the loop transfer function of the stiffness-providing feedback loop to adjust the floor vibration feedforward loop.
The rigidity gain G _k may be set higher than the floor vibration gain G _f to further improve the rigidity of the vibration isolation device. Further, the value of the rigidity gain G _k may be set to zero and the feedback loop may not be operated.

In the above embodiment, as disclosed in FIG. 1, an example in which the present invention is applied to a vibration isolator having a structure in which the air springs 3a, 3b and 3c support the triangular vibration isolator 1. However, the scope of the present invention is not limited to such cases. The essence of the present invention that the gain of the floor vibration feedforward loop is determined by a feedback loop, for example, a loop transfer function of the feedback loop for imparting rigidity can be implemented regardless of the shape of the vibration isolation table. Further, the semiconductor exposure apparatus having the vibration isolation device according to the present invention can be implemented regardless of whether the exposure method is the sequential exposure method or the scanning exposure method.

<Example of Semiconductor Production System> Next, an example of a production system of semiconductor devices (semiconductor chips such as IC and LSI, liquid crystal panels, CCDs, thin film magnetic heads, and micromachines) will be described. This is for maintenance services such as troubleshooting and regular maintenance of manufacturing equipment installed in semiconductor manufacturing plants, or software provision.
This is done using a computer network outside the manufacturing plant.

FIG. 6 shows the entire system cut out from a certain angle. In the figure, 101 is a business office of a vendor (apparatus supplier) that provides a semiconductor device manufacturing apparatus. As an example of the manufacturing apparatus, a semiconductor manufacturing apparatus for various processes used in a semiconductor manufacturing factory, for example, pre-process equipment (exposure apparatus, resist processing apparatus, lithography apparatus such as etching apparatus, heat treatment apparatus, film forming apparatus, planarization apparatus) Equipment) and post-process equipment (assembling equipment, inspection equipment, etc.). In the business office 101, a host management system 10 that provides a maintenance database for manufacturing equipment is provided.
8. A plurality of operation terminal computers 110, and a local area network (LAN) 109 that connects these to construct an intranet. Host management system 10
Reference numeral 8 has a gateway for connecting the LAN 109 to the Internet 105, which is an external network of the office, and a security function for limiting access from the outside.

On the other hand, 102 to 104 are manufacturing factories of semiconductor device makers as users of manufacturing equipment. The manufacturing factories 102 to 104 may be factories belonging to different manufacturers or may be factories belonging to the same manufacturer (for example, a factory for pre-process, a factory for post-process, etc.). In each of the factories 102 to 104, a plurality of manufacturing apparatuses 106 and a local area network (LAN) 111 that connects them and constructs an intranet.
And a host management system 107 as a monitoring device for monitoring the operating status of each manufacturing device 106. Host management system 1 provided in each factory 102-104
07 includes a gateway for connecting the LAN 111 in each factory to the Internet 105, which is an external network of the factory. As a result, the host management system 108 on the vendor 101 side can be accessed from the LAN 111 of each factory via the Internet 105, and only the limited user is permitted to access by the security function of the host management system 108. Specifically, each manufacturing device 106 is connected via the Internet 105.
In addition to notifying the vendor of the status information indicating the operating status of the device (for example, the symptom of the manufacturing device in which the trouble has occurred) from the factory side, the response information corresponding to the notification (for example, the information for instructing the troubleshooting method, the countermeasure Software and data), the latest software, and maintenance information such as help information can be received from the vendor side. A communication protocol (TCP / IP) generally used on the Internet is used for data communication between the factories 102 to 104 and the vendor 101 and data communication on the LAN 111 in each factory. In addition, instead of using the Internet as an external network outside the factory,
It is also possible to use a high-security leased line network (such as ISDN) without access from a third party. Further, the host management system is not limited to one provided by a vendor, and a user may construct a database and place it on an external network to permit access from a plurality of factories of the user to the database.

Now, FIG. 7 is a conceptual diagram showing the whole system of this embodiment cut out from an angle different from that shown in FIG.
In the above example, a plurality of user factories each equipped with a manufacturing apparatus and a management system of a vendor of the manufacturing apparatus are connected by an external network, and production management of each factory or at least one unit is performed via the external network. The information of the manufacturing apparatus was data-communicated. On the other hand, in this example, a factory equipped with manufacturing equipment of a plurality of vendors and a management system of each vendor of the plurality of manufacturing equipments are connected by an external network outside the factory, and maintenance information of each manufacturing equipment is displayed. It is for data communication. In the figure, reference numeral 201 denotes a manufacturing factory of a manufacturing apparatus user (semiconductor device maker), and a manufacturing apparatus for performing various processes is installed on the manufacturing line of the factory. Has been introduced. In addition, in FIG.
Only 01 is drawn, but in reality, multiple factories are similarly networked. Each device in the factory is a LAN
The host management system 205 manages the operation of the manufacturing line by connecting them at 206 to form an intranet. On the other hand, each business office of a vendor (apparatus supply manufacturer) such as an exposure apparatus maker 210, a resist processing apparatus maker 220, a film forming apparatus maker 230, etc., has host management systems 211 and 22 for performing remote maintenance of the supplied apparatus.
1, 231 which, as mentioned above, comprise the maintenance database and the gateway of the external network. A host management system 205 that manages each device in the user's manufacturing plant, and a vendor management system 211, 2 for each device
21 and 231 are connected to each other via the external network 200 such as the Internet or a leased line network. In this system, if a trouble occurs in any of the series of manufacturing equipment on the manufacturing line, the operation of the manufacturing line is suspended, but the vendor of the equipment in trouble receives remote maintenance via the Internet 200. This enables quick response and minimizes production line downtime.

Each manufacturing apparatus installed in the semiconductor manufacturing factory is provided with a display, a network interface, and a computer for executing the network access software and the apparatus operating software stored in the storage device. The storage device is a built-in memory, a hard disk, or a network file server. The network access software includes a dedicated or general-purpose web browser,
For example, a user interface having a screen as shown in FIG. 8 is provided on the display. The operator who manages the manufacturing apparatus at each factory refers to the screen, and the manufacturing apparatus model (401), serial number (402), trouble subject (403), date of occurrence (404), urgency (4)
05), symptom (406), coping method (407), progress (4)
08) etc. is input to the input items on the screen. The input information is transmitted to the maintenance database via the Internet, and the appropriate maintenance information as a result is returned from the maintenance database and presented on the display. Further, the user interface provided by the web browser further realizes a hyperlink function (410 to 412) as shown in the figure, and the operator can access more detailed information of each item or use the software library provided by the vendor for the manufacturing apparatus. You can pull out the latest version of the software, or pull out the operation guide (help information) for reference by the factory operator.

Next, a semiconductor device manufacturing process using the above-described production system will be described. FIG. 9 shows a flow of the whole manufacturing process of the semiconductor device. In step 1 (circuit design), a semiconductor device circuit is designed. In step 2 (mask manufacturing), a mask having the designed circuit pattern is manufactured. On the other hand, step 3
In (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 the lithography technique using the mask and the wafer prepared above. The next step 5 (assembly) is called a post-process, and step 4
This is a step of forming a semiconductor chip using the wafer manufactured by, and includes an assembly step such as an assembly step (dicing, bonding) and a packaging step (chip encapsulation). In step 6 (inspection), the semiconductor device manufactured in step 5 undergoes inspections such as an operation confirmation test and a durability test. A semiconductor device is completed through these processes and shipped (step 7). The front-end process and the back-end process are performed in separate dedicated factories, and maintenance is performed for each of these factories by the remote maintenance system described above. Information for production management and device maintenance is also data-communicated between the front-end factory and the back-end factory via the Internet or the leased line network.

FIG. 10 shows a detailed flow of the wafer process. In step 11 (oxidation), the surface of the wafer is oxidized. In step 12 (CVD), an insulating film is formed on the wafer surface. In step 13 (electrode formation), electrodes are formed on the wafer by vapor deposition. In step 14 (ion implantation), ions are implanted in the wafer. Step 1
In 5 (resist processing), a photosensitive agent is applied to the wafer. In step 16 (exposure), the circuit pattern of the mask is printed and exposed on the wafer by the exposure apparatus described above. In step 17 (development), the exposed wafer is developed. In step 18 (etching), parts other than the developed resist image are removed. In step 19 (resist stripping), the resist that is no longer needed after etching is removed. By repeating these steps, multiple circuit patterns are formed on the wafer. Since the manufacturing equipment used in each process is maintained by the remote maintenance system described above, troubles can be prevented in advance, and even if troubles occur, quick recovery is possible, and Productivity can be improved.

[0065]

As described above, according to the present invention,
Feed the floor vibration into the air spring to cancel the vibration transmission from the floor to the vibration isolation table. The gain of the feedforward loop is determined according to the gain loop gain setting. For example, it is determined by a loop transfer function of a feedback loop that gives rigidity to the vibration isolation table.
Therefore, the gain adjustment can be easily performed in a short time. The step of adjusting the gain of the same feedforward loop by trial and error, as seen in the conventional vibration isolator, is completely unnecessary. As described above, it is possible to provide a vibration isolation device that is easily adjusted and is capable of suitable vibration control, and a high-precision semiconductor exposure apparatus including the vibration isolation device.

[Brief description of drawings]

FIG. 1 is a diagram showing a configuration of a vibration isolation device according to an embodiment of the present invention.

FIG. 2 is an explanatory diagram showing a configuration of one leg of the vibration isolation device of FIG.

3 is a diagram showing a dynamic model of the vibration isolation device of FIG. 2. FIG.

4 is a block diagram showing a signal transmission path of the vibration isolation device of FIG.

5 is a diagram showing a loop transfer function of a feedback loop for imparting rigidity in FIG.

FIG. 6 is a conceptual view of the semiconductor device production system viewed from a certain angle.

FIG. 7 is a conceptual view of the semiconductor device production system viewed from another angle.

FIG. 8 is a specific example of a user interface.

FIG. 9 is a diagram illustrating a flow of a device manufacturing process.

FIG. 10 is a diagram illustrating a wafer process.

[Explanation of symbols]

1: Vibration isolation table, 2: Floor, 3, 3a, 3b, 3c: Air spring, 4, 4a, 4b, 4c: First acceleration sensor, 5,
5a, 5b, 5c: second acceleration sensor, 6, 6a, 6
b, 6c: controller, 71, 72: integrator, 8: floor vibration gain, 9: rigidity gain, 10: viscosity gain, 1
1, 11a, 11b, 11c: power amplifier, 12, 1
2a, 12b, 12c: Air valves.

Claims (14)

[Claims] 1. A vibration isolation table, an air spring that supports the vibration isolation table, a first acceleration sensor that detects vibration of the vibration isolation table, and the first acceleration sensor that detects the vibration of the vibration isolation table according to a detection signal of the first acceleration sensor. A feedback loop that controls the pressure of the air spring, a second acceleration sensor that detects vibration of the floor on which the air spring is installed, and a pressure of the air spring that is controlled according to a detection signal of the second acceleration sensor. A method of adjusting an anti-vibration device having a feedforward loop, wherein the first step of setting the gain of the feedback loop and the setting of the gain of the feedforward loop are performed according to the setting of the gain of the feedback loop. A method of adjusting a vibration isolation device, comprising: a second step. 2. The feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and the second step is based on a loop transfer function of the feedback loop after the first step. The adjusting method according to claim 1, which is a step of setting a gain of the forward loop. 3. The feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and in the first step, the stiffness imparted to the vibration isolation table is equivalent to the original stiffness of the air spring. Is a step of setting the gain of the feedback loop to be doubled, and the second step is a step of matching the gain setting of the feedforward loop with the gain setting of the feedback loop in the first step. The adjusting method according to claim 1, wherein the adjusting method is provided. 4. An anti-vibration table, an air spring that supports the anti-vibration table, a first acceleration sensor that detects vibration of the anti-vibration table, and the first acceleration sensor that detects the vibration of the anti-vibration table. A feedback loop that controls the pressure of the air spring, a second acceleration sensor that detects vibration of the floor on which the air spring is installed, and a pressure of the air spring that is controlled according to a detection signal of the second acceleration sensor. A vibration isolation device having a feedforward loop, wherein the feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and the gain of the feedback loop equivalently determines the rigidity imparted to the vibration isolation table. An anti-vibration device, which is set to have twice the original rigidity of the air spring. 5. The vibration isolation device according to claim 4, wherein the gain setting of the feedback loop and the gain setting of the feedforward loop are matched. 6. An anti-vibration table, an air spring that supports the anti-vibration table, a first acceleration sensor that detects vibration of the anti-vibration table, and the first acceleration sensor that detects the vibration of the anti-vibration table. A feedback loop that controls the pressure of the air spring, a second acceleration sensor that detects vibration of the floor on which the air spring is installed, and a pressure of the air spring that is controlled according to a detection signal of the second acceleration sensor. A vibration isolation device having a feedforward loop, wherein the feedback loop is a feedback loop that imparts rigidity to the vibration isolation table, and the rigidity imparted to the vibration isolation table is equivalent to the original rigidity of the air spring. The vibration isolation device is characterized in that the setting of the gain of the feedback loop and the setting of the gain of the feedforward loop are made equal to each other. 7. An anti-vibration device adjusted by the adjusting method according to any one of claims 1 to 3 or an anti-vibration device according to any one of claims 4 to 6. Exposure equipment. 8. The exposure apparatus according to claim 7, further comprising a display, a network interface, and a computer that executes network software, and data communication of exposure information of the exposure apparatus through a computer network. Exposure equipment that enables 9. The network software provides a user interface on the display for connecting to an external network of a factory in which the exposure apparatus is installed and accessing a maintenance database provided by a vendor or a user of the exposure apparatus. 9. The device according to claim 8, which makes it possible to obtain information from the database via the external network. 10. A step of installing a group of manufacturing apparatuses for various processes including the exposure apparatus according to claim 7 in a semiconductor manufacturing factory, and a plurality of processes using the group of manufacturing apparatuses. And a step of manufacturing a semiconductor device. 11. A step of connecting the manufacturing apparatus group with a local area network, and data communication of information relating to at least one of the manufacturing apparatus group between the local area network and an external network outside the semiconductor manufacturing factory. The method according to claim 10, further comprising: 12. A semiconductor manufacturing factory, which is different from the semiconductor manufacturing factory, accessing a database provided by a vendor or a user of the exposure apparatus via the external network to obtain maintenance information of the manufacturing apparatus by data communication. 12. The method according to claim 11, wherein data is communicated with the device via the external network for production control. 13. A manufacturing apparatus group for various processes including the exposure apparatus according to claim 7, a local area network connecting the manufacturing apparatus group, and a local area network to outside the factory. A semiconductor manufacturing factory having a gateway that enables access to the external network, and capable of performing data communication of information regarding at least one of the manufacturing apparatus groups. 14. The method according to claim 7, which is installed in a semiconductor manufacturing factory.
10. The exposure apparatus maintenance method according to any one of claims 1 to 9, wherein a vendor or a user of the exposure apparatus provides a maintenance database connected to an external network of the semiconductor manufacturing factory, and the semiconductor manufacturing factory. A step of permitting access to the maintenance database from the inside via the external network; and a step of transmitting the maintenance information accumulated in the maintenance database to the semiconductor manufacturing factory side via the external network. Maintenance method for exposure equipment.