JP2000220690A - Active vibration-absorbing device, exposure device and manufacture of device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To positively place a vibration-absorbing stand smoothly and in a short time from a sealing position to an equilibrium position. SOLUTION: In this active vibration-absorbing device equipped with a vibration-absorbing stand, active supporting legs including an air spring actuator driving and supporting the aforesaid removal stand so as to support the vibration-absorbing stand in such a way as to be vibrationproof, a vibration detecting means AC detecting the vibration of the vibration-absorbing stand, a position detecting means PO detecting the position of the vibration-absorbing stand, feed-back compensation units 19, 20, 22 through 25 for permitting the air spring actuator to generate driving force based on the output from the vibration detecting means and the position detecting means, a position target value outputting part designating the target position of the vibration removal stand, and with a pressure target value outputting part 26 designating a steady output to be generated by the air spring actuator, a function is provided for the pressure target value outputting part, capable of increasing its output in a ramp manner or stepwise, or decreasing the output in a ramp manner or stepwise until the output reaches the value corresponding to the steady output.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an active vibration isolator used in a semiconductor exposure apparatus for printing a circuit pattern of a reticle on a semiconductor wafer, a liquid crystal substrate manufacturing apparatus or an electron microscope. More specifically, an active anti-vibration device capable of suppressing external vibrations propagating to the anti-vibration table and actively canceling vibrations generated by precision equipment mounted on the anti-vibration table, And a device manufacturing method using the same.

[0002]

2. Description of the Related Art Generally, in a semiconductor exposure apparatus such as an electron microscope or a stepper using an electron beam, an XY stage is mounted on a vibration isolator. This anti-vibration device has a function of attenuating vibration by vibration absorbing means such as an air spring, a coil spring, and a vibration-proof rubber. However, in the passive vibration isolator having the vibration absorbing means as described above, even if the vibration propagating from the floor can be attenuated to some extent,
There is a problem that vibrations generated by the XY stage mounted on the apparatus cannot be effectively attenuated. That is, the reaction force generated by the high-speed movement of the XY stage itself shakes the vibration isolator, and this vibration significantly impairs the positioning and stabilization of the XY stage. Further, in the passive vibration isolator, there is a trade-off problem between insulation (vibration isolation) of the vibration propagating from the floor and suppression (vibration suppression) performance of the vibration generated by the high-speed movement of the XY stage itself. In recent years, there has been a tendency to use active vibration isolators to solve these problems. The active vibration damping device can eliminate the trade-off between vibration damping and vibration damping within the range of the adjustable mechanism,
Above all, by applying the feedforward control positively, it is possible to obtain a performance that cannot be achieved by the passive vibration isolation device.

In the above-described active vibration isolator, it is important to satisfy the anti-vibration and vibration-damping characteristics at the equilibrium position. The process of transitioning to a state is also important for ensuring device performance. Specifically, when starting up the vibration-isolation table in the seated state by the operation start command, it is necessary to shift the vibration-isolation table to the equilibrium position without causing the posture of the vibration-isolation table to ramp up. This is because, if the posture of the anti-vibration table is changed during the transition process to the equilibrium position, a situation such as mechanical contact or collision of a precision unit mounted on the anti-vibration table is caused. In addition, even if collisions do not occur, the posture of the anti-vibration table is rampant, which significantly impairs the convergence to the equilibrium position. This leads to a problem of increasing a time lag for shifting the apparatus to an actual operation state.

Here, as a cause of disturbing the attitude of the vibration isolation table, an active vibration isolation apparatus adjusted to minimize the change in the attitude of the vibration isolation table in the actual operation state of the semiconductor exposure apparatus generally has a high gain state. There is something. In such a case, in a large-amplitude operation in which the vibration isolation table is shifted from the seated position to the equilibrium state, the compensator or the drive circuit of the actuator or the like is easily saturated, and thus the attitude of the vibration isolation table is unsteady. It is. Such a situation is not limited to the active anti-vibration device but is a phenomenon that occurs in servo systems in general. In order to avoid this problem, the compensation parameter of the control system is changed between a large amplitude operation such as during driving and a small amplitude operation region near the equilibrium position. However, searching for the optimal parameters between the large-amplitude operation and the small-amplitude operation is complicated, and may cause a new problem of instability at the time of parameter switching. In addition, when the parameter switching is to be realized by discrete electronic components, it is inevitable that the circuit scale will increase.

Another means for avoiding the vibration of the anti-vibration table is to set a temporary target position before the final equilibrium position, first converge to the temporary equilibrium position, and then move to the final equilibrium position. And changing the target position to localize to the final equilibrium position. In other words, the target value of the position is switched in a stepwise manner so that the anti-vibration table is localized at the target position without vibrating. For example, JP
Japanese Patent Application Laid-Open No. 103403/103 discloses such a technique.

For a more detailed understanding, using the drawings,
An apparatus configuration for raising a seated anti-vibration table to an equilibrium position will be described. In FIG. 2, reference numeral 1 denotes a servo valve for supplying / exhausting air of a working fluid to / from an air spring 2, reference numeral 3 denotes a position sensor as position detecting means for measuring a vertical displacement of a vibration isolation table 4, and reference numeral 5 denotes a mechanical spring for preload. , 6 are viscous elements expressing the viscosities of the air spring 2, the preload mechanical spring 5, and the entire mechanism (not shown). The mechanism combined from these components is called the active support leg. Next, the feedback device 7 will be described.

[0007] Vibration detecting means 8 represented by an acceleration sensor
Is subjected to signal processing such as removal of high-frequency noise through a filter circuit 9 and is fed back to a stage preceding the voltage-current converter 10 that drives the servo valve 2. This loop causes damping in the mechanism. Works. Subsequently, the output of the position detection means 3 passes through the displacement amplifier 11 and becomes the input of the comparison circuit 12. The comparison circuit 12 compares the displacement amplifier 11 with the output of the target value generator 13 to calculate a position deviation signal. The position deviation signal is guided to the PI compensator 14, and the voltage-current converter 10 is driven by a signal obtained by adding this output and the output of the filter circuit 9 described above. The mechanism is stabilized by a damping pin group based on the output of the vibration detecting means 8, and is positioned without a steady deviation to the equilibrium position designated by the target value generating unit 13 by a feedback loop based on the output of the position detecting means 3. Here, P means proportional and I means integral operation.

[0008] Now, the target value generation unit 13 determines the vibration isolation table 4.
The equilibrium position to be shifted is specified. As shown in FIG.
_s1And r_s2Switch the target voltage using the switching command signal 15.
It is designed to be replaced. Where r_s2Is the anti-vibration table 4
The target voltage at the position to be localized finally, r_s1Is his hand
The target voltage that specifies the previous position. Seated vibration isolation
Target voltage r_s2Is finally localized to the position specified by
First, the target voltage r_s1The comparison circuit only for a certain time
12 and the anti-vibration table 4 is connected to the final equilibrium position to some extent.
And set the target voltage to r_s2By switching to
To the final equilibrium position. Such a switch
As a result, the anti-vibration table 4 can be finally moved without exhibiting an oscillatory response.
To the equilibrium position of. On the other hand, the eye indicating the final equilibrium position
Standard voltage r _s2Is given to the comparison circuit 12,
The platform 4 localizes with an oscillating response. In other words, the goal
Switching of the voltage does not cause the anti-vibration table 4 to move extra.
With an effective means
is there.

[0009]

As described above, according to the prior art, when the anti-vibration table supported by the active anti-vibration device is localized from the sitting position to the equilibrium position, the operation near the equilibrium position is performed. Unlike the above, a large amplitude operation is performed, so that a compensator or an actuator is saturated. This causes the posture of the anti-vibration table to change during the convergence process from the sitting position to the equilibrium position. Such a disturbance in the posture of the vibration isolation table causes a problem that mechanical contact of the main body structure supported by the active vibration isolation device causes damage and also places a significant burden on the actuator and its driving circuit. ing. Also,
As a result of increasing the convergence time during which the anti-vibration table is localized from the sitting position to the equilibrium position, there is a problem in that the standby time when shifting the device supported by the anti-vibration table to actual operation is increased. In addition, according to the above-described technique of switching the target voltage to localize at the equilibrium position, convergence still takes time.

In view of the above, the present invention provides an active vibration isolator, an exposure apparatus having the same, and a device manufacturing method using the same, wherein the vibration isolator is positioned from a sitting position to an equilibrium position. Smoothly without losing your posture,
It is an object to converge in a short time.

[0011]

In order to solve this problem, an active vibration isolator according to the present invention includes a vibration isolation table, and an air spring actuator for driving and supporting the vibration isolation table.
An active support leg for supporting the vibration isolation table in vibration isolation; vibration detection means for detecting vibration of the vibration isolation table; position detection means for detecting a position of the vibration isolation table; A feedback compensator for generating a driving force in the air spring actuator based on both outputs of the detection means, a position target value output unit for specifying a target position of the vibration isolation table, and the air spring actuator to generate A pressure target value output unit that specifies a steady output, wherein the pressure target value output unit increases the output in a ramp or step shape until the output reaches a value corresponding to the steady output. Alternatively, it has a function of decreasing the value corresponding to the steady-state output in a ramp or stepwise manner.

An exposure apparatus according to the present invention includes a stage device for holding a substrate and positioning the substrate at an exposure position, and an active vibration isolator supporting the stage device, and exposing the substrate positioned at the exposure position to an exposure position. The exposure apparatus according to the present invention is characterized in that the above-mentioned invention is provided as an active vibration isolator.

Further, in the device manufacturing method of the present invention, the substrate is held by the stage device and positioned at the exposure position.
While exposing the positioned substrate, at this time, the stage device is mounted on an active anti-vibration device, the vibration is removed, and in a method of manufacturing a device, the device of the present invention is used as an active anti-vibration device. And ramping or ramping down the output of the air spring actuator until it reaches a steady state output at which it should occur, or ramping down from the steady state output. .

According to this, the output of the air spring actuator corresponds to the equilibrium position at the time of the float operation for localizing the anti-vibration table from the sitting position to the equilibrium position or at the time of the down operation for localizing from the equilibrium position to the sitting position. The position of the anti-vibration table smoothly and quickly converges to the equilibrium position or the seating position by ramping up or stepping down from the steady output until reaching the steady output.

[0015]

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

[0016]

FIG. 1 shows an active vibration isolator according to an embodiment of the present invention. Prior to the description based on this drawing, the mechanical configuration of the active vibration isolation device will be described with reference to FIG. In the figure, reference numeral 16 denotes an XY stage mounted on a vibration isolation table 17;
Reference numerals -1, 18-2, and 18-3 denote active support legs for supporting the vibration isolation table 17. The active support leg 18 includes an acceleration sensor AC, a position sensor PO, a servo valve SV, and an air spring actuator AS necessary for controlling one axis in each of a vertical direction and a horizontal direction. . Here, the symbols attached to the hyphens such as AC and PO in the figure indicate the directions according to the coordinate system in the figure and the locations of the active support legs. For example, Y2 refers to the active support leg 18-2 arranged on the left side in the Y-axis direction.

Returning to FIG. 1, the operation of the active vibration isolator will be described. First, acceleration sensors AC-Z1, AC-Z2, AC-Z3, AC-X, which are representatives of vibration detecting means.
The outputs of AC-Y2, AC-Y2, and AC-Y3 are subjected to appropriate filtering processing such as removal of high-frequency noise, and are immediately input to the motion mode extraction / calculation means 19 relating to acceleration. Its output motion mode acceleration signals (a _x, a _{y,
a z, aθ x, aθ y} , the aθ _z). In order to set an optimum damping for each motion mode, motion mode acceleration signals _{(a x, a y, a} z, aθ x, aθ y, aθ z) is guided to the gain compensator 20 about the next stage of the acceleration signal I have. By adjusting this gain, an optimum damping characteristic can be obtained for each exercise mode. This loop is called an acceleration feedback loop.

Next, PO-Z1, PO-Z2, PO-Z
3, PO-X1, PO- Y2, PO-Y3 is a position sensor as a representative of the position detecting means, the output is the output of the position target value output section _{21 (Z 10, Z 20,} Z 30, X
₁₀ , Y ₂₀ , Y ₃₀ ) to obtain position error signals (e _z1 , e _z2 , e _z3 , e _x1 , e _y2 , e _y3 ) of each axis. These position deviation signal, the total of six degrees of freedom of motion mode position error signals (e _x translational and rotational movement about each axis of the anti-vibration table _{17, e y, e z,} eθ x, eθ y, eθ z ) Is guided to the motion mode extraction / calculation means 22 for the position signal for calculating and outputting. These output signals are guided to a PI compensator 23 that adjusts the position characteristics with almost no interference for each motion mode. This loop is called a position feedback loop.
The output signal of the gain compensator 20 in the acceleration feedback loop described above and the output signal of the PI compensator 23 in the position feedback loop are added, and the motion mode drive signals (d _x , d _y , d _z , dθ _x , dθ _y , d
θ _z ). Subsequently, this signal becomes an input to the motion mode distribution calculating means 24, and the drive signals (d _z1 , d _z2 , d _z2 , d _z2 ) for driving the servo valves SV in the respective active support legs.
_{d z3, d x1, d y2} , d y3) to generate. Directly, this drive signal is applied to the servo valve SV-Z in each active support leg.
1, SV-Z2, SV-Z3, SV-X1, SV-Y
2, a voltage / current converter 25 (abbreviated as VI conversion in the figure) for supplying a current for opening and closing the valve of the SV-Y3 is excited. And finally, the air spring actuator AS
To generate driving force. In this way, the device that generates a driving force in the air spring actuator AS by the acceleration feedback loop based on the output of the vibration detecting means and the position feedback based on the output of the position detecting means will be referred to as a feedback compensator.

Note that LA-X, LA-θ and LA-Y are
A laser interferometer for measuring the position of the XY stage 16 in the X direction, rotation around the vertical axis, and Y direction, respectively.
This is mounted on the exposure apparatus main body 28. In FIG. 1, the acceleration sensors AC-Z1, AC-Z2, AC-
Z3, AC-X1, AC-Y2, AC-Y3, position sensors PO-Z1, PO-Z2, PO-Z3, PO-X1,
PO-Y2, PO-Y3, and servo valve SV-Z
1, SV-Z2, SV-Z3, SV-X1, SV-Y
2 and SV-Y3, the expression of being mounted on the exposure apparatus main body 28 is adopted, but this is because the active anti-vibration apparatus shown in FIG. is there.

Here, the output of the pressure target value output unit 26 (d
_{z10, d z20, d z30,} d x10, d y20, d y30) is applied to the front stage of the voltage-current converter 25. Therefore, this output has a role of flowing a steady current to the servo valve SV.
When the seated anti-vibration table 17 is located at the equilibrium position, a steady current is supplied to the servo valve SV in advance by the output of the target pressure output unit 26, and the air spring actuator AS is rapidly filled with air. Is done. Since the air required by the air spring actuator AS is rapidly filled at the equilibrium position, the control for setting the output of the acceleration sensor to zero and the correction operation of the servo system for localizing the target position without a steady-state error are extremely slight. It will be. As a result, the vibration isolation table 17
Can be quickly located at the equilibrium position designated by the position target value output unit 21. However, since the internal pressure of the air spring actuator AS is rapidly increased, the correction operation of the closed loop system cannot be performed in time, and the vibration isolating table 17 may be excessively moved from the equilibrium position.

Therefore, according to the present invention, the current of the servo valve for filling the air spring actuator AS with the working fluid air is also ramped together with the ramp-up or stepwise switching of the position target value according to the prior art. Or switch in stages. That is, when the current to the servo valve SV rises in a ramp shape, the current is increased in a ramp shape to a steady current value of the servo valve SV necessary for positioning the vibration isolation table at the equilibrium position. When the current of the servo valve SV is switched in a stepwise manner, a current lower than the final steady-state current is applied within a certain initial period when the vibration isolating table 17 is started, and then the vibration isolating table 17 is moved to the equilibrium position. At a certain time, the current is switched to a bias current for the servo valve SV to flow a required flow rate.

FIG. 4 shows the output (d _z10 , d _z10) of the pressure target value output unit 26 when the anti-vibration table 17 is located at the equilibrium position.
d _z20, d z30, showing the _{d x10, d y20, d y30} ). FIG. 7A shows a signal applied to the floating seat command terminal 27.
At low level, it is a floating command. At this time,
The output of the pressure target value output section 26 shown in FIG. 4B gradually increases from zero, that is, increases in a ramp shape to set a final steady value. Also, FIG.
Is a waveform when the output of the target pressure value output unit 26 is increased stepwise to set a final steady value.

In the above description, the operation of positioning the anti-vibration table 4 from the sitting position to the equilibrium position has been described.
It is needless to say that the present invention can also be applied to the operation of sitting from the equilibrium position. That is, the target position value and the servo valve SV
May be seated by changing the current in a ramp shape or by switching the position target value and the current of the servo valve SV stepwise.
Also, it is the number of stages when performing stepwise switching,
In FIG. 4C, the final value is reached in the second stage,
There is no limitation on the number of stages.

Finally, FIG. 5 shows how the active vibration isolator according to the present embodiment floats and positions the vibration isolation table. FIG.
Is a state of the bias current flowing through the servo valve SV. In the figure, A is a waveform when a step-like bias current is supplied simultaneously with the positioning start command, and B is a waveform when a bias current is supplied to the servo valve in a ramp shape. In response to such a way of supplying the bias current to the servo valve SV, the anti-vibration table is localized at the target position through a transient phenomenon generally shown by the waveform in FIG. That is, when a current is applied to the servo valve SV in a step-like manner as in the related art, the anti-vibration table is localized at the equilibrium position while repeating overshoot and undershoot (waveform A). On the other hand, when the current is supplied to the servo valve in the form of a ramp, it can be seen that the anti-vibration table 17 is localized at the target position without making the ramp violate (waveform B). FIG.
The unit of the vertical axis in (b) is mm, which indicates the displacement of the vibration isolation table in the translation direction. Needless to say, the rotational attitude of the vibration isolation table is not oscillating.

FIG. 5A shows a target pressure output section 26.
Is a current waveform which is supplied to the servo valve SV by the output of the control signal SV. However, it can be used as an output waveform of the position target value output unit 21 as a matter of course. The output of the target pressure output unit 26 and the output of the target position output unit 21 may both have a function of increasing or decreasing in a ramp or stepwise manner to a predetermined value.

<Embodiment of Device Manufacturing Method> Next, an embodiment of a device manufacturing method using the exposure apparatus of the present invention will be described. FIG. 6 shows a flow of manufacturing micro devices (semiconductor chips such as ICs and LSIs, liquid crystal panels, CCDs, thin-film magnetic heads, micromachines, etc.). In step 1 (circuit design), a device pattern is designed. Step 2
In (mask production), a mask on which a designed pattern is formed is produced. On the other hand, in step 3 (wafer manufacture), a wafer is manufactured using a material such as silicon or glass. 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. Next Step 5
(Assembly) is called a post-process, and is a process of forming a semiconductor chip using the wafer produced in Step 4,
It 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. 7 shows the wafer process (step 4).
The detailed flow of is shown. 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. In step 15 (resist processing), a resist is applied to the wafer. Step 16 (exposure) uses the above-described exposure apparatus or exposure method to align and print the circuit pattern of the mask on a plurality of shot areas of 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 production method of this embodiment, it is possible to produce a large-sized device, which was conventionally difficult to produce, at low cost.

[0029]

The effects of the present invention are as follows. (1) The posture of the anti-vibration table does not change during a float operation for localizing the anti-vibration table from the sitting position to the equilibrium position or a down operation for localizing the anti-vibration table from the equilibrium position to the sitting position. Therefore, it is possible to avoid mechanical contact or collision between a precision device mounted on the vibration isolation table or a structural member integrated with the vibration isolation table. (2) Since the anti-vibration table is started up smoothly, the load on the actuator is reduced. (3) Since the convergence to the equilibrium position is fast, the device can be quickly shifted to the operating state. (4) There is an effect that it greatly contributes to the productivity of the exposure apparatus and device manufacturing.

[Brief description of the drawings]

FIG. 1 is a block diagram showing an active vibration isolator according to one embodiment of the present invention.

FIG. 2 is a diagram illustrating the principle of a conventional active vibration isolation device.

FIG. 3 is a diagram showing a mechanical configuration of the active vibration isolation device of FIG. 1;

FIG. 4 is a diagram showing an example of a generated waveform of a pressure target value in the apparatus of FIG. 1;

FIG. 5 is a graph showing a state of floating positioning of a vibration isolation table in the apparatus of FIG. 1 in comparison with a conventional example.

FIG. 6 is a flowchart illustrating a device manufacturing method that can use the exposure apparatus of the present invention.

FIG. 7 is a detailed flowchart of a wafer process in FIG. 6;

[Explanation of symbols]

1: servo valve, 2: air spring, 3: position detecting means,
4: Vibration isolation table, 5: mechanical spring for preload, 6: viscous element, 7:
Feedback device, 8: vibration detecting means, 9: filter circuit, 10: voltage-current converter, 11: displacement amplifier, 1
2: comparison circuit, 13: target value generator, 14: PI compensator, 15: switch command signal, 16: XY stage, 1
7: anti-vibration table, 18-1, 18-2, 18-3: active support legs, 19: motion mode extraction calculation means for acceleration,
20: gain compensator, 21: position target value output unit, 22:
Exercise mode extraction calculation means for position signal, 23: PI
Compensator, 24: Motion mode distribution calculation means, 25: Voltage / current converter, 26: Pressure target value output unit, 27: Levitation seat command terminal, AC: Acceleration sensor, AS: Air spring actuator, PO: Position sensor, SV : Servo valve.

Claims (4)

[Claims] 1. An anti-vibration table having an air spring actuator for driving and supporting the anti-vibration table, an active support leg for anti-vibration support of the anti-vibration table, and detecting vibration of the anti-vibration table. Vibration detecting means, position detecting means for detecting the position of the vibration isolation table, and a feedback compensator for generating a driving force in the air spring actuator based on both outputs of the vibration detecting means and the position detecting means. An active vibration isolator including a position target value output unit that specifies a target position of the vibration isolation table, and a pressure target value output unit that specifies a steady output to be generated by the air spring actuator; The value output unit has a function of increasing the output in a ramp or stepwise manner until reaching the value corresponding to the steady output, or decreasing the output in a ramp or stepwise manner from the value corresponding to the steady output. An active vibration isolator characterized by the following. 2. The position target value output section raises a target position of the vibration isolation table in a ramp shape or a step shape toward a final target equilibrium position, or in a ramp shape or a step shape from the position. The active vibration isolator according to claim 1, further comprising a function of designating descending. 3. An exposure apparatus, comprising: a stage device for holding a substrate and positioning the substrate at an exposure position; and an active anti-vibration device for supporting the stage device, wherein the exposure device exposes the substrate positioned at the exposure position. As a typical anti-vibration device,
An exposure apparatus comprising: the exposure apparatus according to claim 1. 4. A device for holding a substrate by a stage device and positioning the substrate at an exposure position, exposing the positioned substrate, and mounting the stage device on an active anti-vibration device, performing vibration isolation, Wherein the active vibration isolator is ramped or stepped until the output of the air spring actuator reaches a steady output at which it is to be generated. Or a step of ramping down or stepping down from the steady output.