JP2003263227A - Design method for stage control apparatus, aligner and device-manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a design method for stage control apparatus capable of designing a stage easily from measured data, without modeling the stage mathematically and capable of accurately controlling an actual stage. <P>SOLUTION: A device manufacturing method comprises a step of acquiring measured data indicating frequency characteristics of the stage (S10), a step of setting a proportional gain of a targeted value at a predetermined frequency based on the measured data (S14), steps of setting an amount of a leading phase to be compensated at the predetermined frequency and of designing a leading phase compensator for compensating the amount of the leading phase of the stage by acquiring a transfer function from the amount and the predetermined frequency (S16 and S18), a step of setting an integral gain, in response to the set amount and predetermined frequency and designing PI (phase and integral gain) compensator for compensating a gain to be given to the targeted value by acquiring the transfer function (S20) and steps of forming a closed loop including the leading phase compensator and the PI compensator (S22, S24 and S26). <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 an exposure apparatus and a stage control for controlling the operation of a stage configured to be movable while a moving object such as a mask (reticle) and a wafer used in the exposure apparatus is placed. The present invention relates to an apparatus design method and a device manufacturing method.

[0002]

2. Description of the Related Art In the photolithography process in the manufacturing process of microdevices such as liquid crystal displays, semiconductor devices, image pickup devices (CCD, etc.), thin film magnetic heads, etc.
An exposure apparatus is used that projects an image of a circuit pattern formed on a reticle onto a photosensitive substrate such as a wafer or a glass plate whose surface is coated with a photoresist, via a projection optical system.

As one of the exposure apparatuses, there is known a step-and-repeat type exposure apparatus (stepper) in which a pattern of a reticle is collectively reduced and projected onto each shot area of a wafer. When the exposure of one shot area is completed in the stepper, the wafer is moved to perform the exposure of the next shot area, which is sequentially repeated.

Further, in order to expand the exposure range of the reticle pattern, the exposure light from the illumination optical system is limited to a slit shape, and a part of the reticle pattern is reduced and projected onto the wafer using this slit light. An exposure apparatus of a step-and-scan system in which a reticle and a wafer are synchronously scanned with respect to a projection optical system is also used.

The above stepper is provided with a wafer stage configured to be movable while a wafer is placed thereon, and a stage controller for controlling the wafer stage at high speed and with high accuracy. Further, the step-and-scan type exposure apparatus described above includes a wafer stage, a reticle stage that is configured to be movable while the reticle is placed, and a wafer stage that is positioned at high speed and with high accuracy. And a stage control device for synchronously scanning the wafer stage at a constant speed.

Since the wafer stage and the reticle stage provided in the exposure apparatus must be moved at high speed with high accuracy of several nanometers to several tens of nanometers, when designing the stage controller, the wafer stage and the reticle stage are respectively It is necessary to optimally design according to the dynamic characteristics of. Hereinafter, a conventional design method of the stage control device will be described.

FIG. 10 is a flowchart showing an example of a conventional design method for a stage control device. When designing a stage control device, first, a reference signal indicating a target position of the stage is given to a wafer stage or a reticle stage (hereinafter collectively referred to as a stage), and an accurate response characteristic of the stage is given. (Frequency characteristic)
Is obtained (step S50). The data indicating the frequency characteristic of the stage is acquired from the measurement result of the laser interferometer provided corresponding to the stage.

Next, the stage is mathematically modeled based on the data obtained in step S50 (step S52). Here, the mathematical model of the stage is, for example, a transfer function of the stage showing the relationship between the thrust applied to the stage and the speed of the stage with respect to the applied thrust. This transfer function is obtained by fitting a predetermined function (for example, a function represented by a polynomial) to the data obtained in step S50.

After the stage is represented by a mathematical model,
If necessary, the mathematical model is simplified (step S54).
This is mainly to facilitate the handling of mathematical models. Specifically, when the mathematical model of the stage is expressed by a polynomial, the higher-order terms are truncated to reduce the number of terms.

When the above steps are completed, a controller for controlling the modeled stage is designed based on the mathematical model obtained in step S52 or step S54 (step S56). Specifically, a PID control system for controlling the stage and a phase compensation control system for compensating the phase lead (phase lag) of the stage are designed so as to stably and satisfy the desired performance. It should be noted that the controller designed here is a theoretical one that controls a mathematically modeled stage, and specifically, the transfer function of the controller is obtained.

When the controller is designed, next, the designed controller is simulated (step S5).
8). Specifically, when controlling the mathematically modeled stage using the controller designed in step S56, whether or not the mathematically modeled stage can be controlled so as to satisfy the required specifications of the controller. To simulate. As a result of the simulation in step S58, when the controller designed in step S56 does not meet the required specifications (the determination result in step S60 is “N
(In the case of "O"), the process returns to step S50, the data showing the response characteristics of the stage is acquired again, and the step of designing the controller by mathematically modeling the stage is performed.

On the other hand, as a result of the simulation in step S58, if the controller designed in step S56 meets the required specifications (the determination result in step S60 is "YE").
In the case of “S”), the designed controller is realized by software, and a ROM (Read only Memo)
ry) and the like and store it in a storage device such as ry) and mount it on an actual stage controller (step S62). Through the above steps, the stage control device for controlling the actual stage was obtained, but finally, the step of adjusting the stage control device so that the actual device satisfies the required specifications It is performed (step S64). Specifically, since the above-described controller is mounted on the stage control device by software, work for finely adjusting various parameters of the controller is performed.

[0013]

By the way, in the above-described conventional method for designing a stage controller, the step of mathematically modeling the stage based on the data showing the response characteristics of the stage (S52) and, if necessary, the mathematical model. The step of simplifying (S54) is indispensable, and the controller and eventually the stage control device are designed based on the mathematical model of this stage.

In general, it is difficult to obtain an accurate mathematical model based on the actually obtained data showing the response characteristic of the stage. Further, since it is difficult to handle an accurate mathematical model when it is to be obtained, usually, the mathematical model is simplified (approximate) by providing step S54 shown in FIG.
is doing. The stage control device needs to be designed so as to satisfy the specifications (operation characteristics) required by the actual physical system, that is, the actual wafer stage or reticle stage provided in the exposure apparatus. Therefore, if a controller is designed for a model that approximates the stage, it takes a long time to adjust the stage controller so that the stage meets the required specifications when the controller is mounted on an actual stage controller. In addition to this, a great deal of labor is required, resulting in a problem that the cost of the exposure apparatus increases.

The present invention has been made in view of the above problems of the prior art, and it is possible to easily design from the actual measurement data of the stage without modeling the stage, and to actually design the actual stage. An object of the present invention is to provide a design method of a stage control device capable of designing a stage control device that can be accurately controlled, and an exposure apparatus including the stage control device designed using the method.

[0016]

In the following, in the example shown in this section, each constituent element of the present invention is described by attaching a typical reference numeral shown in the drawings of the embodiments for easy understanding. The configuration or each constituent element of the present invention is not limited to those constrained by these reference signs.

1. According to a first aspect of the present invention, in a design method of a stage control device (33) for controlling a stage (RCS, RFS, WS) movably supported,
An actual measurement data acquisition step (S) in which target values are given to the stages (RCS, RFS, WS) to obtain actual measurement data indicating frequency characteristics of the stages (RCS, RFS, WS).
10), on the basis of the measured data, the proportional gain setting step of setting a proportional gain of the target value in a predetermined frequency _{(f m) (K p)} and (S12, S14), the predetermined frequency _{(f m} ), The phase lead amount (φ _m ) to be compensated is set, and a transfer function is obtained from the phase lead amount (φ _m ) and the predetermined frequency (f _m ) of the stage (RCS, RFS, WS). First to compensate the amount of phase lead
First design step (S16, S1) of designing the compensator (56)
8), sets the amount of phase lead set by the first design step (S16, S18) (phi _m) and the integral gain in accordance with said predetermined frequency _{(f m) (K i),} the integral gain ( A second design step (S20) of designing a second compensator (53) for obtaining a transfer function from K _i ) and the proportional gain (K _p ) and compensating the gain given to the target value; and the first compensator. (56) and a closed loop forming step (S22, S24,) for forming a closed loop including the second compensator (53).
S26) is provided.

According to the present invention, the first compensator and the stage for giving the target value to the stage to obtain the actual measurement data indicating the frequency characteristic of the stage and compensating the phase advance amount of the stage based on the actual measurement data. The second compensator for compensating the gain given to the target value to be supplied to is designed, and a closed loop including these first compensator and second compensator is formed. As described above, the present invention provides a stage control device suitable for controlling the stage based on the data showing the response characteristics of the stage actually obtained without mathematically modeling the stage as in the prior art. Because it is designed,
Adjustment of the stage control device so that the stage meets the required specifications does not require much time and labor, and highly accurate adjustment can be performed. Further, since the stage control device is designed based on the data indicating the actual response characteristics of the stage, the controllability of the stage can be improved.

[0019] In stage controller of the present invention, the predetermined frequency (f _m) may be so set in accordance with the bandwidth of the closed loop.

In the stage control device of the present invention, in the proportional gain setting step (S12, S14),
The stage (RCS, RFS, WS) when indicated by the Bode diagram of the frequency characteristic of the proportional gain (K _p of the target value so that the gain curve becomes the predetermined frequency (f _m) at the gain crossover ) Can be set.

Further, in the stage control device of the present invention, the actual measurement data indicating the frequency characteristics of the stages (RCS, RFS, WS) is converted into the stages (RCS, RF).
S, WS) provided for the stage (RCS,
A position measuring device (32,
35, 37) can be obtained from the measurement result.

In addition, in the stage control apparatus of the present invention, the first compensator (56) has a transfer function shown in a Bode diagram to show the frequency characteristic of the first compensator (56).
A first data acquisition step of obtaining data and a second data acquisition of obtaining the second data showing the frequency characteristic of the second compensator (53) by showing the transfer function of the second compensator (53) in a Bode diagram. And an open loop including the first compensator (56) and the second compensator (53) using the measured data, the first data, the second data, and the proportional gain ( _Kp ). An open loop transfer function calculating step (S22) for obtaining a transfer function, and a closed loop characteristic calculating step (S24) for obtaining the gain and phase of the closed loop and the gain and phase of the sensitivity function using the open loop transfer function are further provided. In the closed loop forming step, the closed loop gain and phase calculated in the closed loop characteristic calculating step and the gain and phase of the sensitivity function can be taken into consideration.

2. According to a second aspect of the present invention, in an exposure apparatus that transfers a pattern formed on a mask (R) onto a photosensitive substrate (W), a mask stage (RCS, RFS that holds and moves the mask (R). ) And a substrate stage (WS) that holds and moves the photosensitive substrate (W)
And the mask stage (RCS, RFS) and the substrate stage (W
Stage control device (3) for controlling at least one of
3) is provided.

3. According to a third aspect of the present invention, there is provided a device manufacturing method including an exposure step of transferring a pattern onto a photosensitive object (W) using the exposure apparatus according to the second aspect of the present invention.

[0025]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a stage control apparatus and an exposure apparatus according to embodiments of the present invention will be described in detail with reference to the drawings.

FIG. 1 is a front view showing an exposure apparatus according to the embodiment of the present invention. In the present embodiment, a step-and-scan type reduction projection type exposure apparatus will be described as an example. In the following description, the XYZ orthogonal coordinate system is set as shown in FIG. 1, and the positional relationship of each member will be described with reference to this XYZ orthogonal coordinate system. The XYZ orthogonal coordinate system is set so that the Y axis and the Z axis are parallel to the paper surface and the X axis is set in a direction perpendicular to the paper surface. In the XYZ coordinate system in the figure, the XY plane is actually set to a plane parallel to the horizontal plane, and the Z axis is set to the vertically upward direction.

In FIG. 1, a base member (base or surface plate) 13 is provided on an installation surface 11 via four (only two are shown in FIG. 1) vibration isolation devices (vibration isolation mechanisms) 12. ing. The vibration-damping device 12 is arranged near each of the four corners of the base member 13, and is not particularly limited, but is of a passive type including, for example, a pneumatic damper or a mechanical damper in which a compression coil spring is put in damping liquid. , An active type having an actuator that is displaced so as to suppress the vibration based on a detection signal from a vibration detector (not shown) provided on the base member, or a type having both of these is used. . The base member 13 is a stone,
It is composed of a highly rigid member such as ceramics or iron. The vibration isolator 12 may support the base member 13 at three locations.

A first column 15 holding a projection optical system 14 is provided on the base member 13 and a second column (base or surface plate) 16 is provided on the first column 15. It is provided. A reticle coarse movement stage unit RCS and a reticle fine movement stage unit RFS are provided on the second column 16 as a driving device for moving the reticle R on which a circuit pattern is formed. A wafer stage unit WS is provided on the base member 13 as a drive device for moving the wafer W as a photosensitive substrate. As a result, the reticle R and the wafer W are surfaces having mutually different positions in the direction along the optical axis of the projection optical system 14 (Z direction in FIG. 1).
It is possible to move in a two-dimensional direction (X direction and Y direction) within a plane orthogonal to this optical axis.

In the present embodiment, the scanning direction of the exposure apparatus is set to the Y direction, so drive control of the reticle R and the wafer W in the Y direction will be mainly described. Positioning control of the reticle R and the wafer W in the X direction, a rotation direction around the Z axis (θz direction), and an inclination angle with respect to the XY plane (that is, a rotation amount (pitching amount) around the X axis rotation direction (θx direction), and The adjustment of the rotation amount (rolling amount) in the rotation direction (θy direction) about the Y-axis can be easily performed as usual, and thus the description thereof will be omitted.

The wafer stage WS comprises a stator 17, a mover 18 movable in the Y direction with respect to the stator 17, and a stage 19 mounted on the mover 18. The stator 17 and the mover 18 associated therewith can be provided by a linear motor. In particular, in this embodiment,
The stator 17 is a slide mechanism 20 such as an air bearing.
Is provided so as to be movable in the Y direction on the base member 13. The stator 17 may be fixed on the base member 13. The wafer W having the upper surface coated with the photosensitizer is held on the stage 19 by suctioning and sucking the entire back surface of the wafer W through, for example, a pin chuck holder (not shown). Incidentally, in FIG. 1, the mover 18 and the stage 1
Although 9 is shown as a separate member, they may be provided by a common member. Although not shown, the stage 19 has a table holding the above-mentioned pin chuck holder and three actuators (for example, a voice coil motor or an EI core) for driving the table in the Z-axis direction. The wafer W can be moved not only in the X and Y directions but also in the Z direction and can be rotated in the θx and θy directions (inclinable with respect to the XY plane), that is, can be moved in five degrees of freedom. Here, a fine movement mechanism (not shown) including the above-mentioned three actuators may be used to rotate the table in the θz direction so that the wafer W can be moved in six degrees of freedom, or, similarly to the reticle stage described later, the wafer W can be moved. The stage WS may be a coarse / fine movement stage, for example, the above-mentioned table may be configured to be finely movable in the X and Y directions with respect to the stage 19.

The reticle coarse movement stage unit RCS is
The stator 21, a mover 22 movable in the Y direction with respect to the stator 21, and a stage 23 mounted on the mover 22 are provided. The stator 21 and the mover 22 associated therewith can be provided by a linear motor. In particular, in this embodiment, the stator 21 is provided so as to be movable in the Y direction on the second column 16 by the slide mechanism 24 having an air bearing or the like. The stator 21 may be fixed on the second column 16. In FIG. 1, the mover 22 and the stage 23 are shown as separate members, but they may be provided by a common member.

The reticle fine movement stage unit RFS is
It is provided on the stage 23 of the reticle coarse movement stage unit RCS. Reticle fine movement stage unit RF
The S includes a stator 25, a mover 26 movably provided in the Y direction with respect to the stator 25, and a stage 27 mounted on the mover 26. The stator 25 and the mover 26 associated therewith may be provided by a linear motor. In this embodiment, the stator 25 is the stage 2
It is fixed on 3. Further, in FIG. 1, the mover 26 and the stage 27 are shown as separate members, but they may be provided by a common member. The stage 27 has a function of adsorbing and holding the reticle R having a pattern to be transferred on its surface in the vicinity of its peripheral portion with the pattern forming surface facing downward. In this example, the stage 2 of the reticle fine movement stage unit RFS is different from the stage 23 of the reticle coarse movement stage unit RCS (hereinafter also referred to as coarse movement stage 23).
Although a linear motor (25, 26) is used as a drive mechanism for relatively moving 7 (hereinafter also referred to as a fine movement stage 27), for example, a voice coil motor, an EI core, or a piezo element may be used. Further, in this example, the fine movement stage 23 is movable in the X, Y and θz directions, but in addition to this, in the Z direction, θx and θy.
It may be movable in at least one of the directions.

A third column 29 is provided on the second column 16, and the third column 29 converts the light emitted from a light source such as an excimer laser (not shown) into a predetermined illuminating light, and the reticle. An illumination optical system 30 for guiding to R is attached.

A movable mirror 31 is mounted on the stage 19 for the wafer W, and a laser interferometer 32 (position measuring device) which is a position detecting device corresponding to the movable mirror 31 is attached to the first column 15. Is provided. The position of the stage 19 in the Y direction is measured with a predetermined resolution by the laser interferometer 32 and the movable mirror 31. The measurement value is supplied to a control device 33 that can be provided by computer hardware and software, and the wafer stage unit WS is controlled based on the measurement value to accelerate, decelerate, and scan the stage 19. Movement and positioning are performed. Although not shown, the position detecting apparatus of this example also has a laser interferometer for detecting the position of the stage 19 in the X direction and a movable mirror having a reflecting surface extending in the Y direction, and further θx, θy, and θz. The amount of rotation of the stage 19 in the direction (that is, the amount of pitching, the amount of rolling, and the amount of yawing) can be measured. Instead of the two moving mirrors described above, for example, the end surface of the stage 19 (or the table) may be mirror-finished to form a reflecting surface. Further, as the position detection device of this example, for example, a laser interferometer that detects a positional relationship (interval or the like) in the Z axis direction between the first column 15 holding the projection optical system 14 and the stage 19 may be provided.

A movable mirror 34 is mounted on the stage 23 for the reticle fine movement stage unit RFS, and a laser interferometer 35 as a position detecting device is mounted on the third column 29 so as to correspond to the movable mirror 34. Has been. The position of the stage 23 in the Y direction is measured with a predetermined resolution by the laser interferometer 35 and the movable mirror 34. The measured value is supplied to the control device 33, and the reticle coarse movement stage unit RCS is controlled based on the measured value, whereby the stage 23 is accelerated, decelerated, and moved and positioned during scanning.

A moving mirror 36 is mounted on the stage 27 for the reticle R, and a laser interferometer 37 as a position detecting device is provided on the third column 29 so as to correspond to the moving mirror 36. There is. The position of the stage 27 in the Y direction is measured with a predetermined resolution by the laser interferometer 37 and the movable mirror 36. The measured value is supplied to the control device 33, and the reticle fine movement stage unit RFS is controlled based on the measured value to accelerate the stage 27,
Deceleration and movement and positioning during scanning are performed. Although not shown, the position detecting apparatus of this example also has a laser interferometer for detecting the position of the fine movement stage 27 in the X direction and a movable mirror having a reflecting surface extending in the Y direction, and further θx, θy, and It is possible to measure the rotation amount (yaw amount) of the fine movement stage 27 in at least the θz direction in the θz direction. Instead of the two movable mirrors provided on the fine movement stage 27, for example, the end face of the fine movement stage 27 may be mirror-finished to form a reflection surface, or instead of the movable mirror 36, at least one corner cube type. A mirror may be used.

The illumination optical system 30 is an illumination light that extends a rectangular pattern area of the reticle R into a slit shape (rectangular shape) in a direction (X direction) orthogonal to the scanning direction (Y direction) during scanning exposure. Irradiate from above. The illumination area on the reticle R of the slit-shaped illumination light linear in the X direction is located at the center of the circular visual field on the object plane side perpendicular to the optical axis of the projection optical system 14, and has a predetermined reduction magnification β ( An image of a part of the pattern of the reticle R in the illumination area is projected on the wafer W at a predetermined resolution through the projection optical system 14 of 1/4 in the embodiment. As the projection optical system 14, a reduced inverted image of the pattern formed on the pattern surface of the reticle R is formed on the wafer W.
What is projected on is used.

At the time of scanning exposure, the control unit 33 controls the wafer stage unit WS, the reticle coarse movement stage unit RCS, and the reticle fine movement stage unit RF.
An exposure start command is sent to S, and in response to this, the reticle R is scanned and moved in the + Y direction at the speed Vm, and in synchronization with this, the wafer W is moved in the -Y direction at the speed Vw.
The scanning is moved at (= β · Vm). The reticle R is moved in the -Y direction at the same speed ratio and the wafer W
May be moved in the + Y direction.

At this time, paying attention to the reticle coarse movement stage unit RCS, the reaction force acts on the stator 21 as the mover 22 and the stage 23 accelerate or decelerate, and the stator 21 slides in this embodiment. Since it is movable with respect to the second column 16 by 24, the stator 21 tends to move in the direction opposite to the moving direction of the mover 22. A reaction frame mechanism is used to prevent the influence of the reaction force generated thereby.

The reaction frame mechanism acts on the stator 21 by the reaction frame 38 provided independently of the second column 16 (therefore, the base member 13) and the movement of the stage 23 arranged on the reaction frame 38. And a reaction force device that generates a force that cancels the reaction force. Particularly, in this embodiment, a passive reaction frame mechanism is adopted, and the reaction force device is the stator 21.
It is provided by a reaction bar 39 which is made of an elastic body or a rigid body and connects the reaction frame 28 with the reaction frame 28.

As a result, the reaction force due to the acceleration or deceleration of the stage 23 is released to the installation surface 11 via the reaction bar 39 and the reaction frame 38, and a certain exposure accuracy is ensured. An active reaction frame mechanism may be configured by providing an actuator that can electrically control expansion and contraction in the middle of the reaction bar 39. Further, similarly, the reaction frame mechanism may be applied to the wafer stage unit WS.

FIG. 2 is a sectional view of a linear motor applicable to the exposure apparatus shown in FIG. This linear motor has a stator S and a mover M that moves relative to the stator S. When this linear motor is applied to the reticle coarse movement stage unit RCS (see FIG. 1), the stator S
1 constitutes a part of the stator 21 shown in FIG. 1, and the mover M constitutes a part of the mover 22 shown in FIG. Stator S
Includes a frame 40, a coil 41 fixed to the frame 40, and a cover 42 made of a metal plate fixed to the frame 40 and covering the coil 41. Mobile M
Includes a permanent magnet for cooperating with the coil 41 to obtain thrust. The driving force of wafer stage unit WS and the driving force of reticle coarse movement stage unit RCS are provided by a linear motor having substantially the same configuration shown in FIG.

Next, a configuration example of the stage control device provided in the exposure apparatus according to the embodiment of the present invention will be described. FIG. 3 is a block diagram showing a configuration example of a stage control device included in the exposure apparatus according to the embodiment of the present invention. still,
Although FIG. 3 illustrates only the configuration of the portion that controls wafer stage unit WS, similar configurations are provided for reticle coarse movement stage unit RCS and reticle fine movement stage unit RFS. Further, in the following description, a stage control device that PI-controls the wafer stage unit WS will be described as an example.

In FIG. 3, reference numeral 50 denotes an input end to which a reference signal RS1 for giving a target position of the wafer W or the stage 19 (see FIG. 1) of the wafer stage unit WS is inputted. Reference numeral 51 is a calculation unit that outputs a deviation signal ES1 corresponding to the difference between the reference signal RS1 input from the input end 50 and the feedback signal FS2 output from the laser interferometer 32 and passed through the amplifier 59 described later. The position of the stage 19 of the wafer stage unit WS is determined by the laser interferometer 3
2 (see FIG. 1), which results in the generation of the feedback signal FS1. Reference numeral 52 is an output terminal for taking out the deviation signal ES1 output from the arithmetic unit 51.

Reference numeral 53 is a PI compensator, which forms a part of a control device for controlling the wafer stage unit WS which is a control target. This PI compensator 53 is a linear amplifier 5
4 and an integrating amplifier 55. The linear amplifier 54 gives a proportional gain K _p to the input deviation signal ES1, and the integral amplifier 55 gives an integral gain K _i by integrating the output of the linear amplifier 54. In other words, the deviation signal ES1 is linearly amplified by the linear amplifier 54 and further integrated by the integrating amplifier 55.

A phase lead compensator 56, which is a part of a controller for controlling the wafer stage unit WS to be controlled, is provided at the subsequent stage of the PI compensator 53. still,
In the present embodiment, the output response of the wafer stage unit WS which is the control target is slow, and in order to give advance compensation and accelerate the response, the phase advance compensator 56 is provided as a part of the control device.
However, if the output response of the wafer stage unit WS is fast, it is possible to provide a phase delay compensator that provides delay compensation and suppresses the response. The control device including the PI compensator 53 and the phase advance compensator 56 is provided in series with the wafer stage unit WS to be controlled, and the wafer stage unit WS is serially compensated.

The controller composed of the PI compensator 53 and the phase lead compensator 56 described above uses the wafer stage unit W based on the deviation signal ES1 input to the PI compensator 53.
A control signal CS1 relating to the thrust of S is generated. Adder 5
Reference numeral 7 denotes a control signal CS1 output from a phase advance compensator 56 forming a part of the control device and a control signal C related to the thrust of the wafer stage unit WS input from an input end 58.
S2 and S2 are added. This adder 57 has a PI
At the stage of designing the compensator 53 and the phase lead compensator 56,
The control signal CS2 is provided to supply the control signal CS2 to the wafer stage unit WS when obtaining data indicating the response characteristic (dynamic characteristic) of the wafer stage unit WS.

Reference numeral 59 is a feedback signal F for adjusting the feedback amount when the feedback signal FS1 output from the laser interferometer 32 is fed back to the arithmetic unit 51.
This is an amplifier that gives a predetermined gain to S1 to generate a feedback signal FS2. As shown in the figure, the laser interferometer 3
The feedback signal FS1 output from the output terminal 2 can be extracted from the output end 60, and the feedback signal FS2 indicating the amount of feedback to the calculation unit 51 can be extracted from the output terminal 61.

According to the above configuration, the control signal CS2 is input from the input end 58 without inputting the reference signal RS1 from the input end 50.
, The feedback signal FS1 output from the output end 60 is obtained, and the relationship between the control signal CS2 and the feedback signal FS1 is obtained, the data indicating the response characteristic of the wafer stage unit WS can be obtained.

Further, the reference signal RS1 is input from the input end 50 without inputting the control signal CS2 from the input end 58, the feedback signal FS1 output from the output end 60 is obtained, and the reference signal RS1 and the feedback signal FS1 are obtained. If the relationship of
An open loop gain and phase angle between 0 and the output 60 can be obtained. Further, from the input terminal 58, the control signal CS
The reference signal RS1 is input from the input end 50 without inputting 2 and the feedback signal FS2 output from the output end 61 is obtained,
If the relationship between the reference signal RS1 and the feedback signal FS2 is calculated,
From the input end 50 to the PI compensator 53 and the phase lead compensator 56
Also, the gain and phase angle of the closed loop up to the output end 61 can be obtained via the amplifier 59.

Next, a method of designing the control device 33 which is a part of the stage control device shown in FIG. 3 will be described. FIG. 4 is a flowchart showing a design method of the stage control device according to the embodiment of the present invention.

The conventional method of designing a stage controller shown in FIG. 10 approximates a mathematical model of the stage based on the data obtained from the actual response characteristics of the stage.
I was designing a controller to control this mathematical model. Since the actual response characteristics of the wafer stage unit WS and the response characteristics of the mathematical model of the wafer stage unit WS are not exactly the same, when the conventionally designed controller is mounted on the stage controller, the operation specifications of the wafer stage unit WS As described above, the stage controller had to be adjusted over a long period of time to satisfy the required specifications.

In this embodiment, the wafer stage unit W
A method for designing a stage controller suitable for controlling the wafer stage unit WS based on data obtained by actually obtaining response characteristics of the wafer stage unit WS without modeling S as a mathematical model is proposed. It is a thing. Hereinafter, the design method of the stage control device according to the present embodiment will be described in detail. In the following description, a method of designing a stage control device for PI-controlling the wafer stage unit WS will be described as an example.

The stage control device first gives a control signal (target value) indicating the target position of the stage to the wafer stage unit WS, and acquires actual measurement data indicating the accurate response characteristic (frequency characteristic) of the stage (process). S10).
Specifically, when the control signal CS2 is input from the input end 58 in FIG. 3, the measurement result of the laser interferometer 32 as the position measuring device provided for the wafer stage unit WS, that is, the feedback signal FS1 is measured. Obtain data (step S10). Now, when the control signal CS2 is input to the input end 58, the feedback signal FS1 output from the laser interferometer 32 in time series is sampled and quantized in a predetermined sampling period to be digitized. The measured data is defined as follows. The following n is the size of the actual measurement data.

I (n × 1): Element number of actual measurement data w (n × 1): Frequency [Hz] g _data (n × 1): Gain [dB] p _data (n × 1): Phase [degree]

FIG. 5 is a Bode diagram showing an example of the frequency characteristic of the actual measurement data of the wafer stage unit WS obtained in step S10. FIG. 5A is a gain curve,
(B) is a phase curve. This Bode diagram is obtained, for example, by Fourier-transforming the above-mentioned actual measurement data.
In this embodiment, when the measured data is obtained, first, according to the desired band of the closed loop from the input end 50 to the output end 61 via the PI compensator 53, the phase advance compensator 56, and the amplifier 59 shown in FIG. , sets the frequency f _m of the gain crossover Bode (that gain curve of Bode hangs 0 [dB]) _(a predetermined frequency) (step S12).
For example, to set the frequency _{f m} as 1.5 times the frequency _{f m} is the bandwidth of the closed loop.

[0057] When the actually measured data shown were obtained in FIG. 5, band of the closed loop to be determined is if it is 95 [Hz], sets the frequency _{f m} to 63 [Hz]. Referring to FIG. 5, the gain intersection is the frequency f set in step S12.
It is set to a frequency different from _m = 63 [Hz].
Then, when illustrating the frequency characteristics of the wafer stage unit WS in Bode, setting a proportional gain K _p of the linear amplifier 54 such that the frequency of the gain crossover gain curve is a frequency f _m which is set in second process S12 Yes (Step S1
4).

When the measured data shown in FIG. 5 is obtained, for example, when the proportional gain K _p is set to 300,000, the frequency of the gain intersection becomes the frequency f _m = 63 [Hz] set in step S12. Suppose 6A and 6B are Bode diagrams showing an example of frequency characteristics of actually measured data after setting the proportional gain of the linear amplifier 54. FIG. 6A is a gain curve and FIG. 6B is a phase curve. As shown in FIG. 6 (a), it can be seen that the gain at the frequency _{f m} is 63 [Hz] is set to 0 [dB]. Also, FIG.
As can be seen by comparing (b) and FIG. 6 (b), the phase curve hardly changes even if the value of the proportional gain K _p of the linear amplifier 54 is changed.

Next, based on the phase curve shown in FIG.
Compensation for controlling the wafer stage unit WS.
The amount of phase lead should be set (step S16). Frequency now
Number f _mIf the phase is φ, then the wafer stage unit
Phase lead amount φ to be compensated for_mHas a phase margin of 30
It is set to be about 45 degrees. That is,

The phase advance amount φ _m is set so that 30 ≦ phase margin = 180 + (φ + φ _m ) ≦ 45.

[0061] In the example shown in FIG. 6 (b), when the frequency _{f m} is 63 degrees, the phase φ is -228 degrees. Therefore,
The phase lead amount φ _{m is set} to, for example, 8 so that the above equation is satisfied.
Set to 8.6 degrees.

After the above steps are completed, the frequency f _m
And a phase lead compensator 56 for compensating the phase lead amount of the wafer stage unit WS by obtaining a transfer function from the phase lead amount φ _m set in step S16 (step S1
8). The transfer function G _lp (s) of the phase lead compensator 56 is obtained from the following equation (1).

[0063]

[Equation 1]

Here, the variables α and f in the above equation (1) are obtained from the following equations (2) and (3), respectively.

[0065]

[Equation 2]

[0066]

[Equation 3]

In the example shown in FIG. 6, the frequency f _m is 63 [H
z], and the phase lead amount φ _m set in step S16 is 8
Since it was 8.6 degrees, α = 161.476 and f = 645.4752 from the above equations (2) and (3). By substituting the numerical values of the variables α and f into the equation (1), the transfer function G _lp (s) of the phase lead compensator 56 is obtained, and as a result, the phase lead compensator 56 can be designed.

FIG. 7 is a Bode diagram showing an example of the frequency characteristic of the designed phase lead compensator 56, where (a) is a gain curve and (b) is a phase curve. When the phase lead compensator 56 is designed, finally, from the Bode diagram showing the transfer function of the phase lead compensator 56, the gain frequency characteristic g _lp (w) of the phase lead compensator 56 and the phase frequency characteristic p are shown.
_{and l p} (w) are generated (first data acquisition step). The frequency characteristic g of the gain of the loop including the linear amplifier 54, the phase lead compensator 56, and the wafer stage unit WS
_{The temp} (w) and the phase frequency characteristic p _temp (w) are expressed by the following equation (4).

[0069]

[Equation 4]

When the design of the phase lead compensator 56 is completed,
Next, the frequency f _m and the phase advance amount φ _m set in step S16
And the integration gain K _i of the integration amplifier 55 is set from the above, and the integration gain K _i and the linear amplifier 54 set in step S14 are set.
A PI compensator 53 for PI compensating the wafer stage unit WS is designed by obtaining a transfer function from the proportional gain K _{p of the} above (step S20). First, the integral gain K _i of the integrating amplifier 55 is obtained from the following equation (5).

[0071]

[Equation 5]

Referring to the equation (5), the integral gain K _i is set to be equal to or less than the value obtained by dividing the variable f of the equation (3) by the variable α of the equation (2), but the variable α is set in step S16. Is determined by using the phase advance amount φ _m set in step S1 and the variable f is obtained from the frequency f _m and the variable α, so that the integral gain K _i is finally obtained from the frequency f _m and the phase advance amount φ _m. . When the integral gain K _i is set based on the equation (5), the transfer function G _pi (s) of the PI compensator 53 is obtained from the following equation (6) to design the PI compensator 53.

[0073]

[Equation 6]

When the PI compensator 53 is designed, finally, like the phase lead compensator 56, the frequency characteristic g _pi (w) of the gain of the PI compensator 53 is determined from the Bode diagram showing the transfer function of the PI compensator 53. And frequency characteristics p _pi (w) of the phase are generated (second data acquisition step).

When the design of the PI compensator 53 and the phase lead compensator 56 is completed through the above steps, next, the open loop gain frequency characteristic g between the input end 50 and the output end 60 in FIG. _open (w) and phase frequency characteristic p
_open (w) is _calculated from the following equation (7) (step S2
2).

[0076]

[Equation 7]

For the open loop gain frequency characteristic represented by the equation (7), the gain frequency characteristic g _pi (w) of the PI compensator 53 and the phase frequency characteristic p _pi (w) are expressed by the above ( It is added to the frequency characteristic g _temp (w) and the phase frequency characteristic p _temp (w) shown in equation (4). Figure 8
[Fig. 4] is a Bode diagram showing an example of open-loop frequency characteristics, where (a) is a gain curve and (b) is a phase curve.

When the open loop frequency characteristic is calculated, the closed loop frequency characteristic and the sensitivity function from the input end 50 to the output end 61 via the PI compensator 53, the phase advance compensator 56 and the amplifier 59 are calculated. Yes (Step S2
4). The frequency characteristic of the closed loop is calculated using the following equation (8), and the sensitivity function of the closed loop is calculated using the following equation (9).

[0079]

[Equation 8]

[0080]

[Equation 9]

Here, x (w) and y (w) are the real and imaginary parts of the open-loop transfer function, respectively, and should be calculated from the above equation (7) using the following equation (10). You can still,
J in the equation (10) is an imaginary unit (j ² = −1).

[0082]

[Equation 10]

When the closed loop frequency characteristic is calculated from the above equation (8) and the sensitivity function is obtained from the equation (9), the amplifier 59
To form a closed loop (step S26). Through the steps described above, a stage control device for PI controlling the wafer stage unit WS is designed. FIG. 9 is a Bode diagram showing an example of the frequency characteristic of the closed loop.
Is a gain curve, and (b) is a phase curve. Referring to FIG. 9, the gain curve shown in (a) has a gain of almost 0 up to about 100 Hz, and referring to the phase curve shown in (b), the stage control device designed in this embodiment It can be seen that it is stable up to about 100 Hz.

According to the embodiment of the present invention described above,
The stage is designed to control the stage based on the data showing the response characteristics of the stay obtained without actually modeling the stage mathematically. When adjusting the stage control device so as to meet the required specifications, it does not require much time and labor, and highly accurate adjustment can be performed. Further, since the stage control device is designed based on the data indicating the actual response characteristics of the stage, the controllability of the stage can be improved.

In FIG. 3, the phase lead compensator 56 is
In the latter stage, a loop shaping filter (G _ls (s))
Can be installed. As the loop shaping filter, a notch filter usually used for suppressing the first-order mode of mechanical resonance can be adopted,
Since the phase may become too small and the control band may be impaired, it is desirable to adopt a filter in which a normal notch filter is improved so that its zero point and damping amount can be adjusted.

The embodiments described above are described for facilitating the understanding of the present invention, and are not described for limiting the present invention. Therefore, each element disclosed in the above-described embodiments is intended to include all design changes and equivalents within the technical scope of the present invention.

For example, in the above-described embodiment, the case where the stage controller for controlling the PI of the wafer stage unit WS is designed has been described as an example. However, the stage controller and the P controller for PID control of the wafer stage unit WS. It is also applicable when designing a stage control device that operates. Further, in FIG. 3, the controller 33 for controlling the wafer stage unit WS has been described as an example, but the reticle coarse movement stage unit RCS and the reticle fine movement stage unit RFS can be designed in the same procedure. it can. Further, in the above-described embodiment, the step-and-scan type reduction projection type exposure apparatus has been described as an example, but the present invention can be similarly applied to a step-and-repeat type exposure apparatus.

Further, in the above-described embodiment, the control device 3
Although 3 is composed of hardware and software, it may be composed of only software. Further, in the above-described embodiment, in order for the stage controller to control the synchronous movement of the reticle stage and the wafer stage, the laser interferometer 35 (position information of the coarse movement stage 23) for detecting the position of the coarse movement stage 23 and the fine movement are used. Although both the laser interferometer 37 (position information of the fine movement stage 27) for detecting the position of the stage 27 is used, the position information of the fine movement stage 27 (laser interferometer 37 without using the position information of the coarse movement stage 23) is used. Output) may be used. In this case, the laser interferometer used for detecting the position of the coarse movement stage 23 may not be provided as the position detecting device described above, and only the laser interferometer used for detecting the position of the fine movement stage 27 may be provided.

In the above-described embodiment, the reaction frame mechanism is adopted as the reaction force processing device for reducing the vibration generated by the reaction force when the reticle stage or the wafer stage is moved. At least one of them, for example, Japanese Patent Laid-Open No. 8-
As disclosed in Japanese Patent No. 63231 or the like, a countermass mechanism that moves a countermass (for example, a stator of a linear motor) so as to cancel the reaction force by using the law of conservation of momentum may be adopted. Or a stator of a linear motor for driving the reticle stage or wafer stage is arranged on the installation surface 11, or provided on the installation surface 11 separately from the base member (column, frame, etc.) on which each stage is arranged. You may employ | adopt the structure arrange | positioned at a member. Further, in the above-described embodiment, the first column 15 is installed on the base member 13 to fix the projection optical system 14, but a vibration isolation device different from the vibration isolation device 12 supporting the base member 13 may be used. The first column 15 may be configured to be supported, or a cable such as electric wiring or piping connected to the reticle stage or the wafer stage may be held, and the stage may be moved (following). A movable cable carrier may be provided, and the point is that the configuration of the exposure apparatus to which the present invention is applied is not limited to that shown in FIG. 1 and may be arbitrary. At this time, for example, a twin stage configuration in which two independently movable wafer stages are arranged on the base member 13 may be adopted, or similarly, the reticle stage may be a twin stage configuration, or a single reticle stage may be provided. A plurality of reticles may be held along the scanning direction.

Further, the exposure apparatus of the present invention comprises a semiconductor element,
Circuit patterns on glass substrates, silicon wafers, etc. to manufacture reticles or masks as well as exposure devices used to manufacture liquid crystal displays, plasma displays, thin film magnetic heads, image pickup devices (CCD etc.), and micromachines. It can also be applied to an exposure device that transfers

The light source of the exposure apparatus to which the present invention is applied is not particularly limited, and a KrF excimer laser (wavelength 248 nm), an ArF excimer laser (wavelength 193n).
m), F ₂ laser (wavelength 157 nm), Kr ₂ laser (wavelength 146 nm), KrAr laser (wavelength 134 n)
m), Ar ₂ laser (wavelength 126 nm), etc. can be used.

Further, for example, a single-wavelength laser in the infrared range or visible range emitted from a DFB semiconductor laser or a fiber laser is amplified by a fiber amplifier doped with erbium (or both erbium and ytterbium), and further, You may use the harmonic wave which carried out wavelength conversion into the ultraviolet light using the nonlinear optical crystal.

By the way, in the microdevice, the step of designing the function / performance of the circuit, the step of producing the reticle (mask), the step of producing the substrate (semiconductor wafer, glass plate), and the step of exposing the substrate A step of applying a resist as a material, a step of transferring the pattern of the reticle onto the substrate by using the exposure apparatus described in the above embodiment, an assembly step,
And it is manufactured through inspection steps and the like.

The exposure apparatus of the above-described embodiment assembles a stage device including a large number of components such as the reticle fine movement stage unit RFS, the reticle coarse movement stage unit RCS, and the wafer stage unit WS, and also includes the illumination optical system 30, the alignment system, After the elements such as the projection optical system 14 are assembled electrically, mechanically, or optically connected to each other, optical adjustment is performed and further comprehensive adjustment (electrical adjustment,
It is manufactured by checking the operation). It is desirable to manufacture such an exposure apparatus in a clean room where the temperature and cleanliness are controlled.

[0095]

As described above, according to the present invention,
A target value is given to the stage to obtain actual measurement data indicating the frequency characteristic of the stage, and based on the actual measurement data, the first compensator for compensating the phase advance amount of the stage and the gain to be given to the target value supplied to the stage are set. The compensating second compensator is designed to form a closed loop including the first compensator and the second compensator. As described above, in the present invention, based on the data showing the response characteristics of the stay actually obtained without mathematically modeling the stage as in the conventional case,
Since we have designed a stage controller suitable for controlling the stage, it does not require much time and effort when adjusting the stage controller so that the stage meets the required specifications, and it is highly accurate. The effect is that adjustments can be made.

Since the stage controller is designed based on the data showing the actual response characteristics of the stage,
There is an effect that the stage can be accurately controlled.

[Brief description of drawings]

FIG. 1 is a front view showing an exposure apparatus according to an embodiment of the present invention.

FIG. 2 is a sectional view of a linear motor applicable to the exposure apparatus shown in FIG.

FIG. 3 is a block diagram showing a configuration example of a stage control device included in the exposure apparatus according to the embodiment of the present invention.

FIG. 4 is a flowchart showing a design method of the stage control device according to the embodiment of the present invention.

5A and 5B are Bode diagrams showing an example of frequency characteristics of measured data of the wafer stage unit WS obtained in step S10, in which FIG. 5A is a gain curve and FIG. 5B is a phase curve.

FIG. 6 is a Bode diagram showing an example of frequency characteristics of measured data after setting a proportional gain of a linear amplifier,
(A) is a gain curve, (b) is a phase curve.

FIG. 7 is a Bode diagram showing an example of frequency characteristics of the designed phase lead compensator, where (a) is a gain curve and (b) is a phase curve.

FIG. 8 is a Bode diagram showing an example of open-loop frequency characteristics, where (a) is a gain curve and (b) is a phase curve.

FIG. 9 is a Bode diagram showing an example of frequency characteristics of a closed loop, where (a) is a gain curve and (b) is a phase curve.

FIG. 10 is a flowchart showing an example of a conventional design method for a stage control device.

[Explanation of symbols]

32 ... Laser interferometer (position measuring device) 33 ... Control device (stage control device) 35 ... Laser interferometer (position measuring device) 37 ... Laser interferometer (position measuring device) 53 ... PI compensator (second compensator) 56 ... phase lead compensator (first compensator) f m _... frequency (predetermined frequency) K i _... integral gain _{K p} ... proportional gain R ... reticle (mask) RCS ... reticle coarse movement stage unit (stage, the mask stage) RFs ... Reticle fine movement stage unit (stage, mask stage) W ... Wafer (photosensitive substrate) WS ... Wafer stage unit (stage, substrate stage) φ _m ... Phase advance amount

Claims (7)

[Claims] 1. A method of designing a stage control device for controlling a movably supported stage, comprising: a step of giving a target value to the stage to obtain actual measurement data indicating frequency characteristics of the stage; Based on the measured data, a proportional gain setting step of setting a proportional gain of the target value at a predetermined frequency, and setting a phase lead amount to be compensated at the predetermined frequency,
A first design step of designing a first compensator for obtaining a transfer function from the phase lead amount and the predetermined frequency and compensating for the phase lead amount of the stage; and the phase lead amount and the phase lead amount set in the first design step. A second design step of designing a second compensator which sets an integral gain according to a predetermined frequency, obtains a transfer function from the integral gain and the proportional gain, and compensates the gain given to the target value; A closed loop forming step of forming a closed loop including a compensator and the second compensator. 2. The method of designing a stage controller according to claim 1, wherein the predetermined frequency is set according to a band of the closed loop. 3. In the proportional gain setting step, when the frequency characteristic of the stage is shown in a Bode diagram, the proportional gain of the target value is set so that the gain curve becomes a gain intersection at the predetermined frequency. The method for designing a stage control device according to claim 1 or 2, characterized in that: 4. The actual measurement data indicating the frequency characteristic of the stage is obtained from a measurement result of a position measuring device provided on the stage for measuring the position of the stage. A method for designing a stage control device according to any one of 1. 5. A first data acquisition step of obtaining first data indicating a frequency characteristic of the first compensator by showing a Bode diagram of the transfer function of the first compensator, and a transfer function of the second compensator. A second data acquisition step of obtaining the second data indicating the frequency characteristic of the second compensator by using a Bode diagram, and using the measured data, the first data, the second data, and the proportional gain. The first compensator and the second
An open loop transfer function calculating step of obtaining an open loop transfer function including a compensator, and a closed loop characteristic calculating step of obtaining the gain and phase of the closed loop and the gain and phase of the sensitivity function using the open loop transfer function are further included. 5. The method according to claim 1, wherein the closed loop forming step is formed in consideration of the gain and phase of the closed loop and the gain and phase of the sensitivity function calculated in the closed loop characteristic calculating step. A method of designing a stage control device according to item. 6. An exposure apparatus that transfers a pattern formed on a mask onto a photosensitive substrate, a mask stage that holds and moves the mask, and a substrate stage that holds and moves the photosensitive substrate. An exposure apparatus, which is designed by using the method described in any one of 1 to 5 and includes a stage control device that controls at least one of the mask stage and the substrate stage. 7. A device manufacturing method comprising an exposure step of transferring a pattern onto a photosensitive object by using the exposure apparatus according to claim 6.