JPH11204406A - Method and device for positioning, and aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To shorten a time required for positioning a moving stage, by reducing an effect of vibration when driving/controlling positioning of the moving stage. SOLUTION: A wafer stage positioning control part 80 drives a wafer stage driving motor 76 for positioning control of a wafer stage WS based on the output from a wafer stage interferometer 78 for detecting position of the wafer stage WS and the output from a tacho-generator 74 for detecting rotational speed of the wafer stage driving motor which drives the wafer stage. Based on the signal outputted from an acceleration sensor 92 which, provided near a fixing part of a fixed mirror 72, detects vibration of the fixed mirror 72, a signal related to a local vibration generated near the fixed mirror 72 is discriminated, and the wafer stage WS is positioning-controlled based on the signal.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a positioning apparatus and an exposure apparatus, and more particularly, to a positioning apparatus for driving a moving stage by an actuator, a positioning method, and an exposure apparatus having a positioning apparatus.

[0002]

2. Description of the Related Art With the increase in precision of step-and-repeat type exposure apparatuses, that is, precision instruments such as so-called steppers, micro-vibrations acting on a surface plate (anti-vibration table) from an installation floor are insulated at a micro G level. Need to be done. As a vibration isolation pad for supporting a vibration isolation table of a vibration isolation device, various types such as a mechanical damper in which a compression coil spring is put in a damping liquid and a pneumatic damper are used. In particular, an air spring anti-vibration device having a pneumatic damper can be set to a small spring constant and insulates vibrations of about 10 Hz or more, and is therefore widely used for supporting precision equipment. Recently, an active anti-vibration device has been proposed in order to overcome the limitations of the conventional passive anti-vibration device (for example, see Japanese Patent Application Laid-Open No. H8-166043, which is the same applicant as the present application). This is an anti-vibration device that detects the vibration of the anti-vibration table with a sensor and controls the vibration by driving the actuator based on the output of this sensor. Ideal vibration with no resonance peak in the low frequency control band It can have an insulating effect.

The above-mentioned vibration isolation table is controlled on the assumption that the vibration isolation table as a whole is in a rigid body mode, that is, the vibration isolation table and the objects mounted on the vibration isolation table vibrate together without being elastically deformed. . For this reason, structures such as a vibration isolation table and a column (wattle-shaped frame) mounted on the vibration isolation table are designed to increase rigidity.

[0004] A moving stage capable of precise positioning is provided on the vibration isolation table described above. The position of the moving stage is controlled based on the result measured by the interferometer. The interferometer emits coherent light toward a fixed mirror installed on a fixed member fixed to the vibration isolation table and a movable mirror installed on the movable stage, and is reflected by the fixed mirror and the movable mirror. The relative distance between the fixed member and the moving stage is measured by the interference light generated by the returned light.

[0005]

However, as the positioning accuracy of the moving stage is required to be higher, the vibration of the object mounted on the vibration isolation table in the local elastic mode cannot be ignored. Here, the vibration in the local elastic mode will be described. The vibration in the local elastic mode refers to local vibration generated by bending and vibrating devices and structures installed on the vibration isolation table.

[0006] In a conventional anti-vibration table, the equipment installed on the anti-vibration table is premised on vibrating as a single rigid body integrally with the anti-vibration table. In other words, it is assumed that the vibration isolation table and the devices installed on the vibration isolation table are integrally controlled by performing vibration isolation on the vibration isolation table by the above-described active vibration isolation device. However, due to the above-mentioned “bending”, the vibration isolation table and the device do not vibrate integrally, and a relative vibration may occur between the two. This is the vibration in the local elastic mode (hereinafter, the vibration in the local elastic mode is referred to as “local elastic vibration”).

When the above-mentioned local elastic vibration occurs,
The moving stage installed on the vibration isolation table may cause a positioning error as described below. Here, a positioning error caused by the above-described local elastic vibration will be described with reference to FIG.

FIG. 7 shows an example in which the anti-vibration table is applied to a projection exposure apparatus used in a process of manufacturing an IC, a liquid crystal glass substrate, or the like. 1 shows a schematic configuration of a stage positioning control system.

In FIG. 7, the table 100 is vibrated by an active vibration isolation system (not shown). A projection lens holding cylinder 104 is fixed to the surface plate 100 so as to penetrate therethrough. A motor 108 is mounted on the lower frame 102 fixed to the surface plate 100.
The substrate stage 106 driven by the substrate is installed, and a substrate 116 such as an IC wafer is placed on the substrate stage 106.
Is placed. The illumination system 12 is provided above the projection lens holding barrel 104 via a column 101 fixed to the base 100.
4 is fixed. Further, a mask stage 103 is provided above the projection lens holding barrel 104, and a mask 122 is provided above the mask stage 103. Then, the pattern of the mask 122 illuminated by the illumination system 124 is reduced and projected on the surface of the substrate 116 via a lens provided in the projection lens holding cylinder 104.

At this time, the substrate stage 106 repeatedly moves and stops, and the above-described reduced projection is performed while the substrate stage 106 is stopped. The stage control circuit 120 controls the motor 108 based on the stage position information output from the interferometer 110, thereby controlling the movement, positioning, and stopping of the stage.

A part of the laser light emitted from the light emitting / receiving section 110a of the interferometer 110 passes through the half mirror 118 and is a target surface provided on the side surface of the moving stage 106 (hereinafter, referred to as a moving mirror). The light is reflected by 106R, re-transmits through the half mirror 118, and re-enters the light emitting / receiving unit 110a as measurement light. On the other hand, of the laser light emitted from the light emitting and receiving unit 110a, the light reflected by the half mirror 118 is reflected by the mirror 112 and guided to a reference surface (hereinafter, referred to as a fixed mirror) 114. The light reflected by the fixed mirror 114 passes through the mirror 112 and the half mirror 118 to re-enter the light emitting / receiving unit 110a as reference light. The interferometer 110 measures the position of the moving stage 106 using the interference light generated by the reference light and the measurement light.

As explained above, the interferometer 110 is
The position of the substrate stage 106 is determined by the optical path length difference between the optical path length between the fixed mirror 114 fixed to the projection lens holding barrel 104 and the interferometer 110 and the optical path length between the movable mirror 106R and the interferometer 110. measure. Therefore, the lower frame 10
When the local elastic vibration described above occurs in the projection lens holder 2 or the projection lens holding tube 104, a relative displacement occurs between the fixed mirror 114 and the interferometer 110. Therefore, an error occurs in the measurement value of the substrate stage position by the interferometer 110. This is the error caused by local elastic vibration. Since this error is caused by local elastic vibration as described above, it is difficult to remove the error by the active vibration isolation system. Therefore, the positioning accuracy of the moving stage 106 is reduced until the vibration becomes sufficiently small. In order to perform precise positioning, it is necessary to wait for the local elastic vibration to subside, which has caused a decrease in the throughput of the projection exposure apparatus.

According to the present invention, even if a local elastic mode vibration is generated in a device or a structure installed on the vibration isolation table or the vibration isolation table itself, a decrease in the positioning performance due to the vibration is suppressed, and the positioning performance is excellent. A positioning device, a positioning method using the positioning device, and an exposure apparatus including the positioning device.

[0014]

FIG. 3 shows an embodiment of the present invention.
The present invention will be described with reference to FIG. (1) The invention according to claim 1 is a moving stage WS.
Driving means 76 for driving moving stage WS
And light generated by the light reflected by the reference surface 72 provided on the fixed member 46 fixed to the installation portion of the moving stage WS, and the light reflected by the target surface WSr provided on the moving stage WS. Interferometer position detecting means 78 for detecting the position of the moving stage WS by interference light; vibration detecting means 92 for detecting vibration locally occurring on the reference surface 72; signals output from the interferometer position detecting means 78; Vibration detection means 92
The above-described object is achieved by having the control unit 80 that controls the driving of the driving unit 76 based on the output signal. (2) The invention according to claim 2 further includes speed detecting means 74 for detecting the moving speed of the moving stage WS; the control means 80 controls the signal output from the speed detecting means 74 and the interferometer position detection. The signal output from the means 78 is used as a feedback signal and the vibration detecting means 9 is used.
2 is used as a feedforward signal to control the driving of the driving means 76. (3) The control means 80 according to the third aspect of the present invention.
Is to multiply the signal output from the vibration detecting means 92 by a predetermined gain to convert the signal into a thrust value generated from the driving means 76. (4) The invention according to claim 4 is a moving stage WS.
Driving means 76 for driving moving stage WS
And light generated by the light reflected by the reference surface 72 provided on the fixed member 46 fixed to the installation portion of the moving stage WS, and the light reflected by the target surface WSr provided on the moving stage WS. Interferometer position detecting means 78 for detecting the position of the moving stage WS by interference light; vibration detecting means 92 for detecting vibration locally occurring on the reference surface 72; speed detecting means 74 for detecting the moving speed of the moving stage; The present invention is applied to a positioning method of a positioning device having Then, a predetermined gain is given to the signal output from the vibration detecting means 92 while performing feedback control of the driving means 76 based on the signals output from the interferometer position detecting means 78 and the speed detecting means 74, and The driving means 76 is converted into a generated thrust value and output to perform feedforward control. (5) The invention according to claim 5 is a mask stage RS
An exposure apparatus for exposing a pattern formed on a mask substrate R installed on a substrate W installed on a substrate stage WS via a projection optical system 46, wherein the exposure apparatus comprises: It is provided with the positioning device described above.

In the section of the means for solving the above-mentioned problems, which explains the configuration of the present invention, the drawings of the embodiments of the present invention are used to make the present invention easy to understand. However, the present invention is not limited to this.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to FIGS. In the following description of the embodiments, the configuration of an exposure apparatus to which the present invention is applied Suppression of vibration in rigid mode (hereinafter referred to as rigid vibration) A positioning method for reducing the influence of local elastic vibration will be described. In the following description, a positioning method for reducing the influence of local elastic vibration is a feature of the present invention.

FIG. 1A shows a schematic configuration of an exposure apparatus 100 to which the present invention is applied. In FIG. 1A, a rectangular plate-shaped pedestal 10 is installed on the floor, and voice coil motors (hereinafter, VCM) 12A to 12D (here, FIG.
In (a), the VCM 12D on the far side of the drawing is not shown). On these VCMs 12A to 12D, air mounts 14A to 14D (however, the air mount 14D on the back side of the drawing is not shown in FIG. 1A) are installed, and a rectangular surface plate 20 is installed thereon. You. Here, as will be described later, in the present embodiment, the Z-axis is taken in parallel with the optical axis of the projection optical system, and the X-axis is set in the longitudinal direction of the platen 20 in a plane perpendicular to the Z-axis. Take the Y axis. The directions of rotation about the respective axes are defined as Zθ, Xθ, and Yθ directions. In the following description, the directions indicated by the arrows indicating the X, Y, and Z axes in FIG. 1 are changed to + X, + Y, +
The Z direction and the opposite direction are used separately from the -X, -Y, and -Z directions.

VCMs 12A to 12D and air mount 14
A to 14D are arranged near four corners of the rectangular bottom surface of the surface plate 20, respectively. Here, referring to FIG. 1B, these VCMs 12A to 12D and air mounts 14A to 14A
4D will be described. In addition, these VCM12A ~
12D or the air mounts 14A to 14D have the same configuration. Here, the VCM 12 and the air mount 14 will be described.

The VCM 12 includes a stator 12a and a movable element 12b. The stator 12a is a fixed frame 14
The movable element 12b is fixed to the lower portion inside the movable frame 14a.
c. The air mount 14 includes a stator 14e and a mover 14f. Air mount 14
Is fixed on the fixed frame 14a, while the mover 14f is connected to the movable frame 14c. With such a configuration, the VCM 12 and the air mount 14
Are transmitted to the movable frame 14c. The thrust of the VCM 12 is adjusted by the control unit 200 (FIG. 3; the control unit 200 will be described later). Compressed air is sent to the air mount 14 from an air pressure source (not shown) via an air supply hole 14b. The control unit 200 (FIG. 4)
The thrust generated from the air mount 14 is adjusted by adjusting the amount of air sent into the air mount 14. A dowel 14d protrudes from the top surface of the movable frame 14c,
This is for positioning by engaging with a hole (not shown) formed in the lower surface of the surface plate 20.

On the upper surface of the surface plate 20, the end on the + Y direction side,
The acceleration sensors 22 and 24 are fixed. An acceleration sensor 26 is fixedly mounted on the upper surface of the surface plate 20 at the end in the −Y direction, and these acceleration sensors 22, 24 and 26 are fixed.
Thus, the vibration of the surface plate 20 is detected. Furthermore, the surface plate 20
Displacement sensors 30 and 32 are fixed near both ends of the side surface on the + X direction side, and a displacement sensor 28 is fixed on the side surface on the −X direction side of the surface plate 20. On the pedestal 10, gate-shaped frames 16 and 18 are fixedly mounted, and displacement sensors 28, 3
0 and 32 detect the relative displacement between the frame 16 or 18 and the surface plate 20. These sensor acceleration sensor and displacement sensor are both control unit 200 (FIG. 4).
Connected to.

Referring now to FIG. 2, a description will be given of the vibration detecting direction or the displacement detecting direction of the acceleration sensors 22, 24 and 26 and the displacement sensors 28, 30 and 32. FIG. 2 shows a surface plate 20 of the exposure apparatus shown in FIG. 1 and a sensor fixed to the surface plate 20. The acceleration sensor 22 includes three acceleration sensors that detect accelerations in the ± X direction, the ± Y direction, and the ± Z direction, respectively. The acceleration sensor 24 includes two acceleration sensors for detecting accelerations in the ± Y direction and the ± Z direction, respectively. The acceleration sensor 26 is a sensor that detects acceleration in the ± Z direction. Similarly, the displacement sensor 30 includes three displacement sensors that detect displacements in the ± X direction, the ± Y direction, and the ± Z direction, respectively. The displacement sensor 28 includes two displacement sensors that detect displacement in the ± Y direction and ± Z direction, respectively. The displacement sensor 32 is configured by a sensor that detects displacement in the ± Z direction. In the following description, if necessary, for example, the ± Y direction,
The acceleration sensors for detecting acceleration in the Z direction are represented as acceleration sensors 24Y and 24Z, respectively. The displacement sensors are similarly expressed as displacement sensors 30X, 30Y, 30Z and the like. A method for detecting vibration and displacement of the surface plate 20 using these acceleration sensors and displacement sensors will be described later.

Referring again to FIG. 1, the configuration of exposure apparatus 100 will be described. Y fixed on the upper part of the frame 18
An actuator 34, and a Y actuator 38 and an X actuator 4 fixed on the upper part of the frame 16.
2 will be described. The Y actuators 34, 38
The X actuator 42 is for giving a thrust in the ± X direction to the surface plate 20, and the X actuator 42 is for giving a thrust in the ± X direction to the surface plate 20. Blocks 3 are provided on the upper surface of the surface plate 20 so as to face the respective actuators.
6, 40 and 44 are fixed. The thrust generated from each actuator is transmitted to the surface plate 20 via the blocks 36, 40, and 44 facing the respective actuators. These Y actuators 34, 3
As the 8 and X actuators 42, electromagnetic actuators including magnets and coils are used. Then, these Y actuators 34, 38
And the X actuator 42 are connected to the controller 200 (FIG. 4), and the thrust generated from each actuator is controlled by the controller 200.

The adjustment of the height and horizontal level of the surface plate 20 performed by the control unit 200 (FIG. 4) will be briefly described. The ± Z direction displacement (height) signal of the surface plate 20 detected by the displacement sensors 28, 30 and 32 is input to the control unit 200. Based on this signal, the control unit 200 calculates the thrust to be generated from the air mounts 14A to 14D in order to set the height of the surface plate 20 to a preset value and maintain the horizontal level. After that, the control unit 200 adjusts the amount of air sent from the air pressure source (not shown) to each air mount so that the calculated thrust is generated from each of the air mounts 14A to 14D. After that, the control unit 20
0 controls the thrust generated from the air mounts 14A to 14D so as to maintain the height and the level of the surface plate 20.
Thereby, the surface plate 20 does not generate distortion, and the positioning accuracy and the like of the reticle stage RS and the wafer stage WS are maintained with high accuracy.

A fixed object on the surface plate 20 will be described.
A projection lens holding cylinder 46 is fixed to the surface plate 20 so as to penetrate the surface plate 20. A mask stage is fixed above the projection lens holding cylinder 46. Hereinafter, in the present embodiment, the mask stage will be described as a reticle stage RS. The reticle stage RS is driven in the X and Y directions by a reticle stage drive motor 62 (FIG. 3) described later (details of the reticle stage RS will be described later).

A column 48 is planted on the surface plate 20 so as to surround the projection lens holding tube 46, and a mirror 52 is fixed on the column 48 via a mirror holding unit 54. An illumination optical system 50 is fixed on the upper part of the column 48. Light for exposure is transmitted from a light source (not shown) to the illumination optical system 50.

A lower base 25 is hung below the surface plate 20. The lower base 25 is provided with an XY motor by a motor described later.
A substrate stage driven in a two-dimensional direction is placed. Hereinafter, in the present embodiment, this substrate stage will be described as wafer stage WS. The wafer W is suction-held on the wafer stage WS via a Z leveling stage, a θ stage, and a wafer holder (all not shown).
The wafer W is configured to be three-dimensionally positionable by a Z-leveling stage capable of adjusting a drive in the Z-axis direction and an inclination with respect to the Z-axis, and a θ stage (both not shown) capable of minute rotation around the Z-axis. You.

Referring to FIG. 3, reticle stage RS, wafer stage WS, and reticle stage RS,
A control unit for performing wafer stage WS positioning control will be described.

-Reticle Stage, Reticle Stage Control System-In FIG. 3 schematically showing a main part of the exposure apparatus 100 shown in FIG. 1A, an upper base 64 is fixedly mounted on the upper part of the taking lens holding cylinder 46. You. The reticle stage RS is fixed on the upper base 64. The reticle stage RS is driven in the ± X direction by a reticle stage drive motor 62, and the amount of movement of the reticle stage is measured by a reticle stage interferometer 66. Reticle stage interferometer 6
The light emitted from 6 and transmitted through the half mirror 82 is reflected by the moving mirror RSr, transmitted again through the half mirror 82, and enters the reticle stage interferometer 66 as measurement light.
The light emitted from the reticle stage interferometer 66 and reflected by the half mirror 82 is reflected by the mirror 84, reflected by the fixed mirror 70 fixed on the upper part of the column 48, and then reflected by the mirror 84 and the half mirror 82. Then, the light enters the reticle stage interferometer 66 as measurement light.

The reticle stage interferometer 66 measures the position of the reticle stage RS in the ± X direction using the interference light generated by the measurement light and the reference light. An acceleration sensor 90 is fixed near the fixed mirror 70. This acceleration sensor 9
0 detects vibration in the X direction generated near the fixed mirror 70. The tachogenerator 60 is connected to the reticle stage drive motor 62. This tacho generator 60
It outputs a signal proportional to the rotation speed of the reticle stage drive motor 62, that is, the moving speed of the reticle stage RS. These tacho generator 60 and acceleration sensor 9
0, a signal output from the reticle stage interferometer 66 is input to the reticle stage positioning controller 68.

The reticle stage positioning control unit 68
The reticle stage drive motor 62 is driven based on these signals and a signal input from a wafer stage positioning control unit 80 described later to control the positioning of the reticle stage RS. The reticle stage RS is also driven in the ± Y direction by a drive motor (not shown), the reticle stage position in the ± Y direction is detected by an interferometer (not shown), and the reticle stage positioning control unit 68 controls the position. In the description of the present embodiment, only the positioning control in the ± X direction will be described, and the description of the positioning control in the ± Y direction will be omitted.

-Wafer Stage, Wafer Stage Control System- The wafer stage WS is fixed to the lower base 25. The wafer stage WS is driven in the ± X direction by a wafer stage drive motor 76, and the amount of movement of the wafer stage is measured by a wafer stage interferometer 78. Light emitted from the wafer stage interferometer 78 and transmitted through the half mirror 88 reaches the moving mirror WSr and is reflected. The light reflected by the moving mirror WSr again passes through the half mirror 88 and enters the wafer stage interferometer 78 as measurement light. The light emitted from the wafer stage interferometer 78 and reflected by the half mirror 88 is reflected by the mirror 86, and is reflected by the fixed mirror 72 fixed below the projection lens holding cylinder 46, and then the mirror 86 and the half mirror The light is reflected again at 88 and enters the wafer stage interferometer 78 as measurement light.

The wafer stage interferometer 78 causes the wafer stage WS to operate due to the interference light generated by the measurement light and the reference light.
Is measured in the ± X direction. An acceleration sensor 92 is fixed near the fixed mirror 72. This acceleration sensor 92
Detects vibration in the X direction near the fixed mirror 72.
The tacho generator 7 is mounted on the wafer stage drive motor 76.
4 are connected. The tacho generator 74 outputs a signal proportional to the rotation speed of the wafer stage drive motor 76, that is, the moving speed of the wafer stage WS. The signals output from the tacho generator 74, the acceleration sensor 92, and the wafer stage interferometer 78 are input to the wafer stage positioning controller 80.

The wafer stage positioning controller 80 drives the wafer stage drive motor 76 based on these signals to control the positioning of the wafer stage WS. The wafer stage WS is driven by a drive motor (not shown).
It is also driven in the Y direction, and ±
The wafer stage position in the Y direction is detected, and the position is controlled by the wafer stage positioning control unit 80.
In the description of the present embodiment, only the positioning control in the ± X direction will be described, and the description of the positioning control in the ± Y direction will be omitted.

In the exposure apparatus 100 configured as described above, the main controller sets the illuminating light to be sent from the light source (both not shown) to the illuminating optical system 50, and performs relative positioning (alignment) between the reticle R and the wafer W. ) And auto focus by a focus detection system (not shown). Light emitted from the illumination optical system 50 is reflected by a mirror 52 to illuminate the pattern of the reticle R, and is projected by a projection lens (not shown) fixed inside the projection lens holding cylinder 46.
Is formed on each shot area of the wafer W. The exposure operation and the movement of the wafer stage WS are repeatedly performed.

Suppression of Rigid Body Vibration Next, control of the rigid vibration of the exposure apparatus 100 by the control unit 200 will be described with reference to the circuit block diagram of FIG. The control unit 200 is configured by a computer, and includes the displacement sensors 28, 30, 32 and the acceleration sensor 2
VC such that rigid vibration of exposure apparatus 100 (FIG. 1) including surface plate 20 is suppressed based on outputs from 2, 24, and 26.
The thrust generated by M12A to 12D, Y actuators 34 and 38, and X actuator 42 is controlled.

As shown in FIG. 4, the control unit 200 includes a first coordinate conversion unit 80, six subtractors 82a to 82f, and position controllers XPI, YPI, ZPI, XθPI, and Y.
θPI, ZθPI, and six speed conversion gains 84a-8
4f, a second coordinate conversion unit 86, and six integrators 88a
To 88f, six subtractors 90a to 90f, speed controllers VXPI, VYPI, VZPI, VXθPI,
VYθPI, VZθPI, decoupling calculation unit 94, 7
And thrust gains 96a to 96g. Then, the first coordinate conversion unit 80 includes the displacement sensors 28Y, 28Z, 3
Output signals from 0X, 30Y, 30Z, and 32Z (hereinafter, FIG. 2) are input through A / D converters (not shown), respectively, and the exposure apparatus 100 has six degrees of freedom (X,
Y, Z, Xθ, Yθ, Zθ: Refer to FIG.
y, z, θx, θy, θz). Subtractor 82a
To 82f indicate the displacement amounts (x, y, z, θx, θy, θz) in the six degrees of freedom after conversion by the first coordinate conversion unit 80, as control target values (output from the target value output unit 210). x0, y
0, z0, θx0, θy0, θz0) and the positional deviation in each direction with six degrees of freedom (Δx = x0
−x, Δy = y0−y, Δz = z0−z, Δθx = θx
0−θx, Δθy = θy0−θy, Δθz = θz0−θ
z) is calculated respectively. Position controller XPI, Y
PI, ZPI, XθPI, YθPI, and ZθPI are composed of PI controllers that perform control operations using position deviations Δx, Δy, Δz, Δθx, Δθy, and Δθz in the inertial principal axis coordinate system in the respective directions of six degrees of freedom as operation signals.
The speed conversion gains 84a to 84f are
PI, YPI, ZPI, XθPI, YθPI, ZθPI
From the speed command values x0 ', y0', z0 ', θx
0 ′, θy0 ′, and θz0 ′.

The second coordinate conversion unit 86 includes the acceleration sensor 2
2X, 22Y, 22Z, 24Y, 24Z, and 26Z
2 are input through A / D converters (not shown), and accelerations (x ″, y ″, z ″, θx ″, θy ″, θ) in six directions of freedom.
z "). The six integrators 88a to 88f convert the acceleration components (x", y ", z", θ ") in the respective directions with six degrees of freedom after the conversion by the second coordinate converter 86. x, θ "
y, θ ″ z) are respectively integrated and converted into velocity components (x ′, y ′, z ′, θ′x, θ′y, θ′z) in the respective directions. Six subtractors 90a to 90f Is the speed command value (x) output from the speed command gains 84a to 84f.
0 ', y0', z0 ', θ'x0, θ'y0, θ'z
0) to the outputs of the integrators 88a to 88f (x ', y',
z ′, θ′x, θ′y, θ′z) to reduce the velocity deviation in each direction with six degrees of freedom (Δx ′ = x0′−).
x ′, Δy ′ = y0′−y ′, Δz ′ = z0′−z ′,
Δθ′x = θ′x0−θ′x, Δθ′y = θ′y0−
θ′y, Δθ′z = θ′z0−θ′z) are calculated. Speed controllers VXPI, VYPI, VZPI, VXθ
PI, VYθPI, and VZθPI are velocity deviations Δx ′, Δy ′, Δz ′, Δθ′x in the respective directions having six degrees of freedom.
It is composed of a PI controller that performs a control operation using Δθ′y and Δθ′z as operation signals, and performs speed control in each direction with six degrees of freedom. The decoupling calculation unit 94 includes speed controllers VXPI, VYPI, VZPI, VXθPI, and VXPI.
A decoupling operation for converting the speed control amounts output from YθPI and VZθPI into speed command values to be generated at the positions of the actuators is performed. Thrust gain 96a-9
6g converts the speed command value to be generated at the position of each actuator after conversion by the decoupling calculation unit 94 into a thrust value to be generated by each actuator.

As described above, the control system for suppressing rigid body vibration by the control unit 200 includes an acceleration sensor and an integrator as an inner loop inside a position control loop including a displacement sensor, a position controller, and the like. , A multi-loop control system having a speed control loop including a speed controller and the like. According to this control system, the drive force distribution of the plurality of actuators is determined and controlled so as to drive the surface plate 20 in the direction of six degrees of freedom, thereby increasing the gain of the position control loop and increasing the servo rigidity. Therefore, the vibration from the outside can be effectively cut off and rigid body vibration can be suppressed.

Positioning Method for Reducing the Effect of Local Elastic Vibration With reference to FIGS. 3, 5, and 6, a method for controlling the positioning of the reticle stage RS and the wafer stage WS while reducing the effect of local elastic vibration will be described. . FIG. 5 is a block diagram showing an internal configuration of reticle stage positioning control section 68 and wafer stage positioning control section 80 shown in FIG. Reticle stage positioning control section 68 and wafer stage positioning control section 80 are connected via determination section 167. The reticle stage positioning control unit 68, the wafer stage positioning control unit 80, and the determination unit 167 are all configured by a computer, and perform positioning control of the reticle stage RS and the wafer stage WS as described below.
Main controller 500 that controls the overall operation of exposure apparatus 100 is also connected to wafer stage positioning controller 80.

-Wafer Stage Positioning Control Unit- The wafer stage positioning control unit 80 will be described.
The wafer stage positioning control unit 80 includes an amplifier 152
, Bandpass filter 154, target value setting section 166
, Subtractors 164 and 160, a position amplifier 162, a speed amplifier 158, and an adder 156. The wafer stage positioning control unit 80 includes a signal relating to the vibration of the fixed mirror 72 detected by the acceleration sensor 92 and a wafer stage drive motor 76 output from the tacho generator 74.
Of the rotation speed of the wafer stage interferometer 78
The rotation direction and the rotation speed of the wafer stage drive motor 76 are controlled on the basis of the signal regarding the position of the wafer stage detected in step (1).

The components of the wafer stage positioning controller 80 will be described. A signal output from the acceleration sensor 92 is given a predetermined gain by the amplifier 152. The band-pass filter 154 is for discriminating only signals related to local elastic vibration generated near the fixed mirror 72 among signals output from the acceleration sensor 92. Target value setting section 166 receives information regarding the movement position of wafer stage WS output from main controller 500 and outputs a control target value to subtractor 164. The subtracter 164 obtains a position deviation of the wafer stage WS based on the wafer stage position control target value output from the target value setting unit 166 and the information on the wafer stage position output from the wafer stage interferometer 78. The position amplifier 162 gives a predetermined gain to the position deviation obtained by the subtractor 164. The subtractor 160 has a position amplifier 162
And the signal output from the tacho generator 74 are obtained. The speed amplifier 158 gives a predetermined gain to this signal and converts it into a speed command value. Adder 156 adds the signal output from bandpass filter 154 and the signal output from speed amplifier 158. Wafer stage drive motor 76 rotates in a rotation direction and a rotation speed according to the level of the signal output from adder 156, and drives wafer stage WS.

As described above, the wafer stage positioning controller 80 includes the wafer stage interferometer 78 and the position amplifier 1
A multi-loop system having a speed feedback loop including a tachogenerator 74, a speed amplifier 158, and the like in a position control feedback loop including 62 and the like is provided. Further, the acceleration sensor 92,
A signal relating to local elastic vibration detected, amplified, and discriminated by the amplifier 152 and the band-pass filter 154 is fed-forward input.

As described above, the wafer stage positioning control section 80 controls the reticle stage drive motor 62 in a feedforward manner based on the detection result of the local elastic vibration generated near the mounting portion of the fixed mirror 72. For this reason, it is possible to prevent the wafer stage settling time from deteriorating due to an error in the reticle stage position detected by the wafer stage interferometer 78 due to the influence of local elastic vibration. At this time, a signal output from the acceleration sensor 92 is output from the amplifier 152 to the wafer stage drive motor 7.
6 is converted into the thrust to be generated, so that the control delay can be minimized.

-Reticle Stage Positioning Control Unit-The reticle stage positioning control unit 68 will be described. The reticle stage positioning control unit 68 includes an amplifier 1
51, a band-pass filter 153, and an amplifier 165
, A subtractor 163, 159, a position amplifier 161, a speed amplifier 157, and an adder 155. Reticle stage positioning control section 68 detects a signal related to vibration of fixed mirror 70 detected by acceleration sensor 90, a signal related to rotation speed of reticle stage drive motor 62 output from tachogenerator 60, and a signal detected by reticle stage interferometer 66. The rotation direction and the rotation speed of the reticle stage drive motor 62 are controlled based on a signal regarding the position of the reticle stage.

The components of the reticle stage positioning controller 68 will be described. A signal output from the acceleration sensor 90 is given a predetermined gain by the amplifier 151. The bandpass filter 153 is for discriminating only a signal related to local elastic vibration generated near the fixed mirror 70. The amplifier 165 includes a determination unit 1 described later.
The control target value is output to the subtractor 163 by multiplying the positional deviation amount of the wafer stage WS output from the step 67 by the reduction projection magnification β of the projection lens. The subtracter 163 obtains the position deviation of the reticle stage RS based on the reticle stage position control target value output from the amplifier 165 and the information on the reticle stage position output from the reticle stage interferometer 66. The position amplifier 161 includes a subtractor 163
A predetermined gain is given to the position deviation obtained in the above. The subtractor 159 obtains the difference between the signal output from the position amplifier 161 and the signal output from the tach generator 60. The speed amplifier 157 gives a predetermined gain to this signal and converts it into a speed command value. The adder 155 adds the signal output from the band-pass filter 153 and the signal output from the speed amplifier 157. Reticle stage drive motor 62 rotates in a rotational direction and a rotational speed according to the level of the signal output from adder 155, and drives reticle stage RS.

As described above, the reticle stage positioning controller 68 includes the tachometer 60 and the speed amplifier 157 in a position control feedback loop including the reticle stage interferometer 66 and the position amplifier 161.
And a multi-loop system having a speed feedback loop configured to include Further, the acceleration sensor 9
0, an amplifier 151, and a signal related to local elastic vibration detected, amplified, and discriminated by the band-pass filter 153 are fed forward.

As described above, reticle stage positioning control section 68 drives reticle stage driving based on the detection result of local elastic vibration generated near the mounting portion of fixed mirror 70 in the same manner as wafer stage positioning control section 80. Feed forward control of the motor 60 is performed. For this reason, it is possible to prevent the reticle stage settling time from deteriorating due to an error in the reticle stage position detected by the reticle stage interferometer 66 due to the influence of local elastic vibration. At this time, the signal output from the acceleration sensor 90 is converted by the amplifier 151 into the thrust to be generated by the reticle stage drive motor 62, so that the control delay can be minimized.

-Judgment Unit- Before explaining the judgment unit 167, the wafer stage W
S, the relative positioning method of the reticle stage RS will be described. After one exposure, exposure apparatus 100 drives wafer stage WS to set the next exposure area to an exposure position. At this time, the wafer stage repeatedly moves and stops, but as the circuit pattern formed on the wafer W becomes finer, the required positioning accuracy of the wafer stage WS increases. On the other hand, in order to improve the throughput of the exposure apparatus, it is desired to reduce the time required for moving and positioning the wafer stage WS.
An exposure apparatus for solving this problem is disclosed in Japanese Patent Application Laid-Open No. 7-220998 by the present applicant. This focuses on the following points. 1) The amount of movement of the reticle stage may be originally small, so that the reticle stage can be reduced in size.
Therefore, the response speed at the time of moving and stopping can be higher than the response speed of the wafer stage. 2) In the reduction projection type exposure apparatus, the positioning error of the reticle stage is multiplied by the reduction projection magnification of, for example, 0.25 times. Not as small as an error.

Focusing on the above 1) and 2), the exposure apparatus first controls the movement of the wafer stage, drives the reticle stage when the position of the wafer stage falls within a predetermined error, and controls the projection optical system. The relative position between the reticle image to be formed and the exposure area on the wafer is adjusted.
In other words, the fine adjustment is performed such that the reticle stage having excellent operation responsiveness and having a large allowable value of the positioning resolution and the error comes to the wafer stage.

The determination section 167 of FIG.
When the positioning error of S is input from the subtractor 164 and it is determined that this error is within a predetermined value, the amplifier 165
Output this error. The reticle stage RS is multiplied by the reduced projection magnification β by the amplifier 165.
The positioning control target value on the side is input to the subtractor 163. The determination unit 167 also inputs the positioning error of the reticle stage from the subtractor 163,
S, it is determined that the relative positioning error amount of the wafer stage WS has settled within the allowable error for exposure, and the illumination optical system 5
An exposure operation start signal is issued to a control circuit (not shown) of 0 (FIG. 3).

FIG. 6 shows how the positioning control of wafer stage WS and reticle stage RS is performed by wafer stage positioning control unit 80, reticle stage positioning control unit 68, and determination unit 167 described above.
(A) and (b) show. FIG. 6A shows a wafer stage W
S shows how the reticle stage RS moves for positioning. FIG. 6B shows the positioning error of the wafer stage WS, that is, the time of the signal at point A in the block diagram of the reticle stage positioning control unit 68 in FIG. Indicates a change. FIG. 6C shows a positioning error when feedforward control based on local elastic vibration detected by the acceleration sensor 90 or 92 is not performed.
The graphs shown in FIGS. 6A to 6C all take time t on the horizontal axis.

Referring to FIG. 6, a description will be given of the positioning control of wafer stage WS and reticle stage RS by wafer stage positioning control section 80, reticle stage positioning control section 68 and determination section 167. Based on a stage movement command from main controller 500, wafer stage positioning controller 80 controls wafer stage drive motor 76
And the wafer stage WS approaches the positioning target position by a predetermined distance d (time t1). At this time t1, the determination section 167 outputs a wafer stage positioning error signal to the reticle stage positioning control section 68. Receiving this signal, reticle stage positioning control section 68 controls reticle stage drive motor 62 so as to reduce the relative positioning error between wafer stage WS and reticle stage RS. That is, the position of the reticle stage is controlled so as to follow the position of the wafer stage WS, and the relative positioning error is reduced. FIG.
In the graph of (a), the reticle stage position is obtained by plotting the actual position multiplied by the reduction projection magnification of the projection lens. That is, it corresponds to the position of the reticle image projected on the wafer.

As shown in FIG. 6B, the relative positioning error of the wafer stage WS converges to almost 0 at time t4, and the determination unit 167 sends a signal to the control circuit (not shown) of the illumination optical system 50. A projection exposure start signal is issued. In contrast,
When the feedforward control of the wafer stage WS and the reticle stage RS is not performed based on the vibrations detected by the acceleration sensors 90 and 92, the convergence time of the relative positioning error increases as shown in FIG. As described above, this is affected by local elastic vibration of a member to which the fixed mirrors 70 and 72 are fixed, such as the column 48 and the projection lens holding cylinder 46, and the wafer stage positioning control unit and the reticle stage positioning This is because the control unit vibrates the wafer stage WS and the reticle stage RS. The exposure operation cannot be started until the positioning error shown in FIG. 6C falls within a predetermined value, so that the throughput is reduced.

As described above, according to the exposure apparatus of the present embodiment, the signals output from reticle stage interferometer 66 and wafer stage interferometer 78 and the fixed signals output from acceleration sensors 90 and 92 are used. The positioning of the reticle stage RS and the wafer stage WS is controlled based on the vibration of the fixed parts of the mirrors 70 and 72 (FIG. 5). Thus, the positioning error of wafer stage WS can be quickly converged as shown in FIG. 6B, and the throughput of the exposure apparatus can be improved.
At this time, the signals output from the reticle stage interferometer 66 and the wafer stage interferometer 78 are used as feedback signals, and the signals output from the acceleration sensors 90 and 92 are used as feedforward signals.
The position control stability of the reticle stage RS and the wafer stage WS is excellent, and the adverse effect caused by the above-mentioned error caused by the vibration being superimposed on the stage position signals detected by the reticle stage interferometer 66 and the wafer stage interferometer 78 can be eliminated. Further, the signals output from the acceleration sensors 90 and 92 are multiplied by predetermined gains by the amplifiers 151 and 152 and converted into thrust values generated from the reticle stage drive motor 62 and the wafer stage drive motor 76, so that excellent control responsiveness is obtained. Obtainable. This allows
Quick positioning control of wafer stage WS is possible,
The throughput of the exposure apparatus can be improved.

In the above description of the embodiment, the acceleration sensors 90 and 92 are the columns 48 and the projection lens holding cylinder 46.
However, as long as local elastic vibration generated at the installation portion of the fixed mirrors 70 and 72 can be detected, it may be installed at another place such as the surface plate 20.
FIG. 3 shows only an example in which the acceleration sensors 90 and 92 for detecting vibration in the X direction are installed, but the vibration detection direction by the acceleration sensor is not limited to this direction. That is, when an interferometer that can be positioned in the Y direction or the Z direction in FIG. 3 and measures the stage position in these directions is installed, if an acceleration sensor capable of detecting vibration corresponding to the direction is provided. Good.

Also, an example has been described in which band-pass filters 153 and 154 are used to discriminate only signals related to local elastic vibration among vibrations detected by acceleration sensors 90 and 92. Another acceleration sensor capable of detecting rigid vibration is installed on the panel 20 or the like, and a signal output from the acceleration sensor for detecting rigid vibration is subtracted from signals output from the acceleration sensors 90 and 92 to reduce local elastic vibration. What is detected may be used.

In the above-described embodiment, the case where the positioning apparatus according to the present invention is applied to a step-and-repeat type scanning exposure type exposure apparatus has been described as an example. Even a projection exposure apparatus of the system can be suitably applied since the stage moves on the surface plate.

Further, the positioning apparatus according to the present embodiment is applicable not only to the optical exposure apparatus described in the above embodiment, but also to a charged particle beam exposure apparatus.

In the above embodiment, an example in which the positioning device is applied to an exposure device has been described. However, the present invention is also applicable to a positioning device such as a moving stage that requires precise positioning.

In the correspondence between the above-described embodiment and the claims, the reticle stage RS and the wafer stage WS use the moving stage and the reticle stage driving motor 6
2 and a wafer stage drive motor 76
The moving mirrors RSr and WSr cover the target surface, the surface plate 20 covers the installation section of the moving stage, the reticle stage interferometer 66 and the wafer stage interferometer 78 cover the interferometer position detecting means, and the column 48 and the projection lens holding cylinder 46 cover the target surface. The fixed members, the fixed mirrors 70 and 72 serve as reference planes, the acceleration sensors 90 and 92 serve as vibration detecting means, the reticle stage positioning control section and the wafer stage positioning control section and the determining section 167 serve as control means, and the tachogenerator 60, 74 constitutes a speed detecting means, the reticle stage RS constitutes a mask stage, and the wafer stage WS constitutes a substrate stage.

[0061]

As described above, (1) According to the first aspect of the present invention, the driving based on the signal output from the interferometer position detection and the signal output from the vibration detecting means. Since the driving control of the means is performed, it is possible to reduce the influence of an error generated in the position detection result of the moving stage by the interferometer position detecting means due to the influence of local elastic vibration. This makes it possible to quickly position the wafer stage and improve the throughput of the exposure apparatus. (2) According to the second or fourth aspect of the present invention, a signal output from the speed detecting means and a signal output from the interferometer position detecting means are used as feedback signals,
By using the signal output from the vibration detecting means as the feedforward signal, the position control stability of the moving stage is excellent, and an error due to local elastic vibration is superimposed on the signal output from the interferometer position detecting means. A decrease in the moving stage positioning performance can be suppressed. (3) According to the invention described in claim 3, excellent control responsiveness can be obtained by multiplying the signal output from the vibration detecting means by a predetermined gain and converting the signal into a thrust value generated from the driving means. it can. As a result, the influence of local elastic vibration can be reduced, and the time required for positioning the moving stage can be reduced. (4) According to the fifth aspect of the present invention, it is possible to reduce the influence of local elastic vibration generated in the exposure apparatus and shorten the time required for positioning the mask stage and the substrate stage. Thus, an exposure apparatus with high throughput can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing an example in which a positioning device according to the present invention is applied to an exposure device.

FIG. 2 is a view showing a part of the exposure apparatus shown in FIG. 1, illustrating a surface plate and sensors installed on the surface plate;

FIG. 3 is a diagram showing a part of the exposure apparatus shown in FIG. 1 and illustrating a schematic configuration of a reticle stage and a wafer stage.

FIG. 4 is a block diagram illustrating a control system for suppressing rigid body vibration.

FIG. 5 is a block diagram illustrating a positioning control unit for a reticle stage and a wafer stage.

FIGS. 6A and 6B are diagrams showing how the reticle stage and the wafer stage are positioned and controlled by the reticle stage positioning control unit and the wafer stage positioning control unit, and FIG. 6A shows how the wafer stage and the reticle stage are driven; FIG. 2B is a diagram illustrating how the positioning error of the wafer stage is reduced, and FIG. 2C is a diagram illustrating how the stage positioning control unit according to the related art is affected by local elastic vibration.

FIG. 7 is a diagram illustrating a main part of an exposure apparatus having a stage positioning device according to a conventional technique.

[Description of Signs] 20 Surface plate 46 Projection lens holding cylinder 48 Column 60, 74 Tach generator 62 Reticle stage drive motor 66 Reticle stage interferometer 68 Reticle stage positioning control unit 70, 72 Fixed mirror 76 Wafer stage drive motor 78 Wafer stage interference Total 80 Wafer stage positioning controller 90, 92 Acceleration sensor WS Wafer stage RS Reticle stage RSr, WSr Moving mirror

Claims (5)

[Claims] 1. A moving stage; a driving unit for driving the moving stage; a light reflected on a reference surface provided on a fixed member fixed to an installation portion of the moving stage; Interferometer position detecting means for detecting the position of the moving stage by interference light generated by light reflected on a target surface provided on the stage, and vibration detecting means for detecting vibration locally occurring on the reference surface. And a control unit for controlling the driving of the driving unit based on a signal output from the interferometer position detecting unit and a signal output from the vibration detecting unit. 2. The positioning device according to claim 1, further comprising a speed detecting means for detecting a moving speed of the moving stage, wherein the control means controls a signal output from the speed detecting means and the interference. A positioning device, wherein a signal output from the measured position detecting means is used as a feedback signal, and a signal output from the vibration detecting means is used as a feedforward signal to control the driving of the driving means. 3. The positioning device according to claim 2, wherein said control means multiplies a signal output from said vibration detecting means by a predetermined gain to convert the signal into a thrust value generated from said driving means. Positioning device. 4. A moving stage; driving means for driving the moving stage; light reflected on a reference surface provided on a fixed member fixed to an installation portion of the moving stage; Interferometer position detecting means for detecting the position of the moving stage by interference light generated by light reflected on a target surface provided on the stage, and vibration detecting means for detecting vibration locally occurring on the reference surface. A positioning method for a positioning device having a speed detecting means for detecting a moving speed of the moving stage, wherein feedback control of the driving means is performed based on signals output from the interferometer position detecting means and the speed detecting means. The signal output from the vibration detecting means is given a predetermined gain, converted into a thrust value generated from the driving means, output, and the driving means is turned on. Method for positioning a positioning device, characterized in that the feedforward control. 5. An exposure apparatus for exposing a pattern formed on a mask substrate mounted on a mask stage to a substrate mounted on a substrate stage via a projection optical system, wherein An exposure apparatus comprising the positioning device according to claim 1.