JPH10275770A - Projection aligner - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a projection aligner for an accurate exposure even if a residual vibration exists in an aligner body. SOLUTION: Stages 27 and 20 are controlled by control means 48 and 50 based on a travel signal from a control device 42, the command value of a counter force for the fluctuation of an equipment body 40 is calculated based on the travel signal, and then the command value is subjected to feed forward input to a control circuit 11. Therefore a vibration being generated in the equipment body 40 due to the move of the stages 27 and 20 is largely controlled by a counter force generated by actuators 7 and 32. The residual vibration of the equipment body 40 that cannot be suppressed is detected by sensors 5X, 5Y, and 5Z, and an operation circuit 54 calculates a signal given to the actuator and a feedback signal given to the control means 48 so that a position where a pattern is transferred to a substrate W cannot fluctuate based on the detection result by the sensors.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a projection exposure apparatus, and more particularly, to a method of controlling the vibration of an exposure apparatus main body by driving an actuator based on the output of a vibration sensor as a vibration control method of the exposure apparatus main body. The present invention relates to a projection exposure apparatus that employs a so-called active vibration isolation method.

[0002]

2. Description of the Related Art Conventionally, in a step-and-repeat type reduction projection type exposure apparatus, that is, a precision device such as a so-called stepper, a vibration of an anti-vibration table is detected by a sensor, and an actuator is operated based on an output of the sensor. An active anti-vibration device that performs vibration control by driving is used.

In a stepper or the like, an XY stage (wafer stage) for performing large acceleration / deceleration is mounted on a surface plate held on a vibration isolation pad. A vibration force acts on the exposure apparatus main body due to the force. In the active anti-vibration device, a reverse force (counter force) having the same magnitude as the reaction force accompanying the stage acceleration / deceleration is input in a feedforward manner. An optical lithography apparatus (projection exposure apparatus) that performs such a counterforce feedforward is disclosed in, for example,
No. 121294. This Japanese Unexamined Patent Publication No.
In the optical lithography apparatus disclosed in Japanese Patent Application Laid-Open No. 121294, a force is applied to three actuators by feedforward to suppress the vibration of the main body of the optical lithography apparatus. Further, in this optical lithography apparatus, vibrations that cannot be suppressed even when a force is applied to the actuator by feed forward are obtained from three acceleration sensors arranged at positions facing the actuator and fed back to the three actuators.

[0004]

However, as disclosed in Japanese Patent Application Laid-Open No. 5-121294, vibration which cannot be suppressed even when a force is applied to the actuator by feedforward is obtained from the acceleration sensor and fed back to the actuator. However, it is actually difficult to effectively suppress the residual vibration. That is, if the value of the acceleration sensor is directly fed back to the actuator disposed at the position facing the sensor as in the above-described known example, the position of the vibration center of the apparatus main body is not taken into account, so that the residual vibration can still be suppressed. Is difficult. In addition, in the method of the above-mentioned known example, there is also a disadvantage that it takes time to reduce the residual vibration to a state that does not affect the exposure.

The present invention has been made under such circumstances, and an object of the present invention is to provide a projection exposure apparatus capable of performing high-precision exposure even when residual vibration is present in an exposure apparatus main body. It is to provide a device.

Another object of the present invention is to provide a projection exposure apparatus capable of suppressing residual vibration more quickly.

[0007]

According to the present invention, the pattern of the mask (R) mounted on the first stage (27) is transferred to the second stage (20) via a projection optical system (PL). A) a projection exposure apparatus for transferring onto a substrate (W) mounted on the first stage (27) and the second stage (27);
Stage movement signal output means (42) for outputting a movement signal to at least one of the stages (20); stage control means (48) for controlling the stage based on the movement signal; and the first stage (27). ) And an exposure apparatus main body (40) on which the second stage (20) is mounted.
Vibration sensor for detecting vibration of the (5Z _1, 5Z _2, 5
_{Y 1, 5Y 2, 5X 1} , 5X 2) and; the vibration of the exposure apparatus main body (40); at least one actuator provided in the exposure apparatus main body (40) (4A - 4D, 32A through 32D) and A drive control means (11) for controlling the drive of the actuator so as to suppress it; and a counterforce for a change in the exposure apparatus main body (40) is calculated based on the movement signal, and the drive control means (11).
Counter-force calculating means (52) for feed-forward input to the actuator; a feedback signal for actuator driving provided to the driving control means (11) based on a detection result of the vibration sensor; and the pattern transferred to the substrate (W). And a vibration control calculating means (54) for calculating a stage feedback signal to be given to the stage control means (48) so that the position to be moved does not fluctuate.

According to this, when a movement signal for at least one of the first stage and the second stage is output from the stage movement signal output means, the corresponding stage is controlled by the stage control means based on the movement signal. Is done. At this time, the counterforce calculation means calculates a counterforce command value with respect to the fluctuation of the exposure apparatus main body based on the movement signal, and feeds the command value to the drive control means. Therefore, when the stage moves under the control of the stage control means, most of the vibration generated in the exposure apparatus main body is caused by the actuator whose drive is controlled by the drive control means based on the counterforce command value. It is suppressed by the emitted counterforce. The vibration (residual vibration) of the exposure apparatus main body that cannot be completely suppressed by the counter force is detected by the vibration sensor. Then, the vibration control arithmetic means, based on the detection result of the vibration sensor, an actuator drive feedback signal to be provided to the drive control means and a stage provided to the stage control means so that the position at which the pattern is transferred to the substrate does not change. Is calculated with the feedback signal. Thus, the actuator is driven by the drive control means based on the actuator drive feedback signal, the residual vibration is removed, and the position at which the pattern is transferred to the substrate is changed by the stage control means based on the stage feedback signal. The stage is driven so as not to.

As described above, according to the present invention, the feedback signal for driving each actuator is provided based on the detection result of the vibration sensor, so that the residual vibration of the exposure apparatus main body can be suppressed. Since the stage feedback signal is provided so that the position where the pattern is transferred to the substrate does not change, the mask pattern is completely stationary on the substrate even if there is residual vibration that cannot be suppressed in the exposure apparatus body. The stage moves as if you were doing it. For this reason, high-precision exposure becomes possible, which leads to an improvement in throughput.

In this case, as in the second aspect of the present invention, the first reflecting mirror (27a) provided on the first stage (27) and the second reflecting mirror (27a) provided on the second stage (20). A reflecting mirror (20a) and the exposure apparatus main body (4
0) a third reflecting mirror (44, 46) fixed to a fixed portion outside the stage, the first reflecting mirror (27a) or the second reflecting mirror (20a), and the third reflecting mirror (44, 46). 4
6) irradiating light to measure the position of the first stage (27) or the second stage (20);
X, 30Y, 31X, 31Y), the vibration control calculating means (54) calculates the vibration state of the third reflecting mirror position (44, 46) in a two-dimensional direction in the horizontal plane. Preferably, the vibration state is fed back to the stage control means (48) for controlling at least one of the first stage (27) and the second stage (20). With this configuration, the vibration control calculation means allows the position of the third reflector in the horizontal plane to be 2
The vibration state in the dimensional direction is calculated, and the vibration state is fed back to the stage control means for controlling at least one of the first stage and the second stage.
Even if the position measurement value of the first stage or the second stage by the interferometer includes an error due to the vibration of the position of the third reflecting mirror, the stage control means corrects the error based on the feedback signal. Stage position control becomes possible. Therefore, the stage can be easily controlled so that the position where the pattern is transferred to the substrate does not change.

In the projection exposure apparatus according to the first or second aspect, as in the invention according to the third aspect, the vibration control arithmetic means (54) has three freedoms at a vibration center of the exposure apparatus main body (40). More desirably, a vibration state in a direction of a degree of freedom equal to or higher than the degree is calculated, and the vibration state is fed back to the drive control means (11). With this configuration, the vibration control arithmetic means uses the detection result of the vibration sensor to detect the vibration center at the vibration center of the exposure apparatus main body.
Since the vibration state in the direction of the degree of freedom equal to or more than the degree of freedom is calculated and the vibration state is fed back to the drive control means, each actuator is driven based on this feedback signal, whereby the residual vibration is suppressed more quickly. You.

The center of vibration typically includes the center of gravity of the main body of the exposure apparatus and the center of the principal axis of inertia.

[0013]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below with reference to FIGS.

FIG. 1 is a schematic perspective view of a step-and-scan type projection exposure apparatus 100 according to one embodiment. In FIG. 1, a rectangular plate-shaped pedestal 2 is installed on a floor as an installation surface, and vibration isolation pads 4A to 4D are provided on the pedestal 2 (however, the vibration isolation pad 4D on the back side of the paper surface in FIG. 1 is not shown). ) Is installed, and a rectangular surface plate 6 is installed on these vibration isolation pads 4A to 4D.
Here, as described later, in the present embodiment, the projection optical system P
Since L is used, the Z axis is taken in parallel with the optical axis of the projection optical system PL, the Y axis is set in the plane perpendicular to the Z axis in the longitudinal direction of the platen 6, and the X axis is set in the direction orthogonal to the Z axis. I take the. Also,
The rotation directions around the respective axes are defined as Zθ, Yθ, and Xθ directions. In the following description, FIG.
The directions indicated by the arrows indicating the X, Y, and Z axes are + X, +
The Y, + Z direction and the opposite direction are used to be distinguished from the -X, -Y, -Z directions.

Each of the vibration isolation pads 4A to 4D has a platen 6
Are located near the four corners of the rectangular bottom surface. In the present embodiment, pneumatic dampers are used as the vibration isolation pads 4A to 4D, and the vibration isolation pads 4A
Since the height of ~ 4D can be adjusted, the pneumatic damper also serves as a vertical movement mechanism. Of course, a mechanical damper or the like in which a compression coil spring is put in the damping liquid by providing a vertical movement mechanism separately may be used as the vibration isolation pad.

An actuator 7A is provided between the pedestal 2 and the surface plate 6 in parallel with the vibration isolation pad 4A. As the actuator 7A, a stator 9A made of a magnet and fixed on the pedestal 2 and a mover 8A fixed on the bottom surface of the base 6
Is used. The actuator 7A has an actuator control circuit 11 (not shown in FIG. 1; see FIGS. 2 and 3).
By controlling the current flowing through the coil in the mover 8 </ b> A, the urging force in the Z direction from the pedestal 2 to the bottom surface of the surface plate 6 or the attraction force from the bottom surface of the surface plate 6 toward the pedestal 2 is generated.

In the other vibration isolating pads 4B to 4D, actuators 7B to 7D having the same configuration as the actuator 7A are installed in parallel with the vibration isolating pad 4A, respectively (provided that the actuator on the back side of the paper in FIG. 1 is provided). 7
C and 7D are not shown), these actuators 7B to
The urging force or suction force of 7D is also set by an actuator control circuit 11 (not shown in FIG. 1; see FIGS. 2 and 3), which will be described later. The control method of the actuators 7A to 7D will be described later.

On the side surface on the + X direction side of the surface plate 6, acceleration sensors 5Z ₁ and 5Z ₂ as vibration sensors for detecting acceleration in the Z direction of the surface plate 6 are mounted. In addition, surface plate 6
The acceleration sensors 5Y ₁ and 5Y ₂ as vibration sensors for detecting the Y-direction acceleration of the surface plate 6 are attached to the + X direction end of the upper surface, and the + Y direction end and the −Y direction end of the surface Acceleration sensors 5X ₁ and 5X ₂ as vibration sensors for detecting the X-direction acceleration of the surface plate 6 are attached.
These acceleration sensors _{5Z 1, 5Z 2, 5Y 1} , 5
As Y ₂ , 5X ₁ , and 5X ₂ , for example, a semiconductor acceleration sensor is used. These acceleration sensors 5Z ₁ , 5
The outputs of Z ₂ , 5Y ₁ , 5Y ₂ , 5X ₁ , and 5X ₂ are supplied to a vibration control arithmetic circuit 54 (not shown in FIG. 1, see FIGS. 2 and 3) described later.

On the surface plate 6, a wafer stage 20 as a second stage is mounted. This wafer stage 2
0 is actually mounted on the X stage 20X driven by the linear motor (not shown) in the X direction along the upper surface of the platen 6 as shown in FIG. A Y stage 20Y driven by a linear motor (not shown) in the Y direction and a Z leveling stage 20Z mounted on the Y stage 20Y are shown in FIG. It is shown as A wafer W as a substrate is placed on this wafer stage 20, specifically a leveling stage 20Z, via a wafer holder 21 capable of minute rotation in the θ direction.
Is held by suction.

A first column 24 is implanted on the surface plate 6 so as to surround the wafer stage 20, and a projection optical system PL is fixed to the center of the upper plate of the first column 24. The second column 2 surrounds the projection optical system PL on the upper plate.
6, a reticle stage 27 as a first stage is mounted on an upper plate of the second column 26, and a reticle R as a mask is mounted on the reticle stage 27.

The side surfaces of the wafer stage 20 (actually the leveling stage 20Z) in the + Y direction and the + X direction are mirror-finished to form reflection surfaces 20a and 20b as second reflection mirrors. Wafer Y-axis interferometer 30Y, wafer X-axis interferometer 30X via these reflecting surfaces 20a and 20b.
(Hereinafter, these may be collectively referred to as “wafer interferometer 30”.) The movement position in the Y direction and the movement position in the X direction of the wafer stage 20 are respectively measured (this is described below). , Further described below). Z
The leveling stage 20Z is driven in the Z-axis direction and XY
The inclination with respect to the surface is configured to be adjustable. Therefore,
The wafer W can be three-dimensionally positioned by the X stage 20X, the Y stage 20Y, the Z / leveling stage 20Z, and the wafer holder 21.

The reticle stage 27 includes a reticle R
The fine adjustment in the X-axis direction and the adjustment of the rotation angle are possible. The reticle stage 27 is driven in the Y direction by a linear motor (not shown). + X direction of this reticle stage 27, + X
The side surfaces in the direction are mirror-finished to form reflection surfaces 27a and 27b as first reflection mirrors. These reflecting surfaces 2
The reticle stage 27 is moved in the Y direction by a reticle Y-axis interferometer 31Y and a reticle X-axis interferometer 31X (hereinafter sometimes collectively referred to as a “reticle interferometer 31”) via 7a and 27b. The movement positions in the X direction are respectively measured (this will be further described later).

Further, an illumination optical system (not shown) is disposed above the reticle R, and a control device 42 (not shown in FIG. 1, see FIGS. 2 and 3), which will be described later, adjusts the relative positions of the reticle R and the wafer W. While performing (alignment) and auto-focusing by a focus detection system (not shown), the pattern of the reticle R is projected onto each shot area on the wafer W via the projection optical system PL under the illumination light EL for exposure from the illumination optical system. Are sequentially exposed. In the present embodiment, when exposing each shot area, the wafer stage 20 and the reticle stage 27 are operated by respective stage control circuits (which will be described later) in accordance with an instruction from the control device 42, and linear circuits (not shown) are used. Scanning is performed relative to each other at a predetermined speed ratio in the Y-axis direction (scanning direction) via a motor in opposite directions.

The first column 24 has four legs 24a.
1 to 24d (however, the leg 24d on the back side of the paper surface in FIG. 1 is not shown) and is in contact with the surface plate 6. A movable shaft 35A is embedded in a side surface of the first column 24 in the −Y direction, and an actuator 32A is mounted between the movable shaft 35A and a column (not shown) fixed on the floor.

As the actuator 32A, similarly to the actuator 7A, a voice coil composed of a stator 34A made of a magnet and fixed to a support (not shown) and a mover 33A including a coil attached to a movable shaft 35A. Motor is used. This actuator 3
2A can apply a force in the ± X direction to the movable shaft 35A by adjusting the current flowing through the coil in the mover 33A by the actuator control circuit 11 described later. Similarly, a movable shaft 35B is embedded in a side surface of the first column 24 in the + Y direction, and an actuator 32 is provided between the movable shaft 35B and a support (not shown) fixed on the floor.
An actuator 32B having the same configuration as A is attached,
Controlled by an actuator control circuit 11 described later,
A force can be applied to the movable shaft 35B in the ± X directions.

An actuator 32C having the same configuration as the actuator 32A is installed between the central portion of the side surface of the first column 24 in the + Y direction and a column (not shown) on the floor, and is controlled by an actuator control circuit 11 described later. A force can be applied to the first column 24 in the ± Y direction via the actuator 32C. Similarly, the first
An actuator 32D having the same configuration as the actuator 32A is installed between the central portion of the side surface in the −Y direction of the column 24 and a support (not shown) on the floor, and is controlled by an actuator control circuit 11 described later.
, A force can be applied to the first column 24 in the ± Y direction. These actuators 32A to 32D
Is also described later.

FIG. 2 shows a configuration of a vibration control system for the exposure apparatus main body 40 constituting the projection exposure apparatus 100, together with the exposure apparatus main body 40 to be controlled.
Here, the exposure apparatus main body 40 is a body including the surface plate 6, the first column 24, and the second column 26 of FIG. 1 described above, the wafer stage 20, a projection optical system PL, and a reticle mounted on the body. Refers to a component configured by the stage 27 and the like.

As described above, this exposure apparatus main body 40
Although two vibration isolation pads 4A to 4D and four Z-direction actuators 7A to 7D are supported from below, in FIG.
These are typically shown as the vibration isolation pad 4 and the Z-direction actuator 7. Further, the exposure apparatus main body 40 includes:
Two Y-direction actuators 3 for Y-direction vibration control
2C and 32D, and are supported by two X-direction actuators 32A and 32B for X-direction vibration control. In FIG. 2, these four actuators are representatively shown as the actuator 32. .

Further, the exposure apparatus body 40 has two acceleration sensors 5X ₁ and 5X ₂ which are arranged at spatially separated positions on the surface plate 6 to measure acceleration in the X direction. , Two acceleration sensors 5Y ₁ and 5Y ₂ that measure the acceleration in the Y direction arranged at a spatially separated position, and the acceleration in the Z direction similarly arranged at a spatially separated position on the surface plate 6 Acceleration sensors 5Z ₁ , 5Z ₂
In FIG. 2, the acceleration sensors 5X ₁ and 5X ₂ are representatively shown as an acceleration sensor 5X, and the acceleration sensors 5Y ₁ and 5Y
₂ is representatively shown as an acceleration sensor 5Y, and the acceleration sensors 5Z ₁ and 5Z ₂ are typically shown as an acceleration sensor 5Z.

Here, measurement of the positions of the reticle stage 27 and the wafer stage 20 will be described with reference to FIG.

The reflecting surface 27a is formed on the side surface in the + Y direction of the reticle stage 27 as described above, and a fixed mirror 44 as a third reflecting mirror is fixed to the upper part of the outer periphery of the projection optical system PL. I have. Helium-neon laser light is emitted from the reticle Y-axis interferometer 31Y toward the reflection surface 20a and the fixed mirror 44, and is mounted on the reticle stage 27 with the reticle Y-axis interferometer 31Y based on the fixed mirror 44. The position of the reticle R in the Y direction is measured.

The reflecting surface 20a is formed on the side surface in the + Y direction of the leveling stage 20Z constituting the wafer stage 20 as described above, and a fixed mirror 46 as a third reflecting mirror is provided on the lower part of the outer periphery of the projection optical system PL. Has been fixed. Helium-neon laser light is emitted from the wafer Y-axis interferometer 30Y toward the reflection surface 20a and the fixed mirror 46, and the wafer Y-axis interferometer 30Y is mounted on the wafer stage 20 with the fixed mirror 46 as a reference. The position of the wafer W in the Y direction is measured.

Here, Y of reticle R and wafer W
Although only the position measurement in the direction has been described, the reticle X-axis interferometer 31X and the wafer X-axis interferometer 30X for measuring the X-direction position also measure the positions of the reticle R and the wafer W in the X direction in the same manner. .

Next, the configuration of a vibration control system for the exposure apparatus main body 40 will be described with reference to FIGS. 2 and 3 (a diagram showing the detailed configuration of each unit in FIG. 2). This control system
As shown in FIG. 2, a control device 42 for controlling the entire apparatus, a reticle stage control circuit 48, a wafer stage control circuit 50, and a counter force operation circuit 5
2, a vibration control arithmetic circuit 54 and an actuator control circuit 11 are provided. In the present embodiment, the control device 42
The reticle stage control circuit 48 forms a stage control means, the counter force calculation circuit 52 forms a counter force calculation means, and the vibration control calculation circuit 54 forms a vibration control calculation means. Is configured.

An arithmetic circuit 54 for vibration control includes an arithmetic circuit 54A based on a center of gravity for calculating a vibration based on a center of gravity G (indicated by ★ in FIG. 2) as a vibration center of the exposure apparatus main body 40, and a reticle. A fixed mirror reference for calculating vibration based on a fixed mirror for use (fixed mirror 44 shown in FIG. 2 and fixed mirror for X-axis not shown: hereinafter, these are collectively referred to as “fixed mirror 44”) And an arithmetic circuit 54B.

The arithmetic circuit 54A of the center of gravity criterion, six acceleration sensor _{5X 1, 5X 2, 5Y 1} , 5Y 2, 5Z 1, 5
By performing a predetermined matrix operation based on the output of Z ₂ , a function of obtaining vibrations in six degrees of freedom (X, Y, Z, Xθ, Yθ, Zθ) at the center of gravity G of the exposure apparatus main body 40 is provided. ing. The center of gravity G of the exposure apparatus main body 40
Is obtained in advance on the design, also six acceleration sensor _{5X 1, 5X 2, 5Y 1} , 5Y 2, 5Z 1, 5Z 2
Are also predetermined. Thus, six of the acceleration sensor _{5X 1, 5X 2, 5Y 1} , 5Y 2, 5Z 1, 5Z 2
By performing a predetermined matrix operation on the basis of the output of the exposure apparatus, it is easy to obtain the vibration in the direction of six degrees of freedom at the position G of the center of gravity of the exposure apparatus body 40. However, since the position G of the center of gravity of the exposure apparatus main body 40 fluctuates due to the movement of the reticle stage 27 and the wafer stage 20, in the present embodiment, the positions of the reticle stage 27 and the wafer stage 20 are determined by a simulation experiment or the like in consideration of this. Are calculated in advance, and the coefficients of these matrix operations are stored as map data in a memory in the arithmetic circuit 54A based on the center of gravity, and the measured values of the reticle interferometer 31 and the wafer interferometer 30 are used as the center of gravity. It is supplied to the reference arithmetic circuit 54A. Furthermore, in the present embodiment, the eight actuators 7A to 7D, 32A to
32D, the arithmetic circuit 54A performs a matrix operation for causing the eight actuators to further share the vibration in the six-degree-of-freedom direction at the center of gravity G of the exposure apparatus main body 40, and controls the actuator control circuit 11 for each actuator. The signal is provided as a feedback signal via

The arithmetic circuit 54B of the fixed lens criterion, six acceleration sensor _{5X 1, 5X 2, 5Y 1} , 5Y 2, 5Z 1,
By performing a predetermined matrix operation on the basis of the output of the 5Z _2, it has a function of determining the vibration of the two-degree-of-freedom directions of XY direction with fixed mirror 44 as a reference. The position of the fixed mirror 44 for the reticle is determined in advance in design, and
Since the positions of the two acceleration sensors are also predetermined,
The coefficients of a matrix for converting signals obtained by the two acceleration sensors into vibrations in the X and Y directions of the fixed mirror 44 for the reticle can be easily obtained. The fixed-mirror-reference arithmetic circuit 54B calculates the vibration in the XY directions of the fixed mirror 44 as the reference position of the reticle R by calculation, and gives the calculation result to the reticle stage control circuit 48.

The controller 42 includes a reticle interferometer 3
1 and the measurement values of the wafer interferometer 30 are supplied via a reticle stage control circuit 48 and a wafer stage control circuit 50 (see FIG. 2). The control device 42 manages and controls the position, speed, and acceleration of the X stage 20X, the Y stage 20Y, and the reticle stage 27. That is, in the control device 42, based on the measurement values of the reticle interferometer 31 and the wafer interferometer 30,
As shown in FIG. 3, the position, speed and acceleration command values for each stage are calculated and the stage control circuit 4 is operated.
A command value of the position of each stage is given as a target value to each of the stages 8 and 50, and command values of speed and acceleration are fed-forward input to a stage control system in the stage control circuits 48 and 50 as described later. It has become.

The reticle stage control circuit 48 is shown in FIG.
, A subtractor 48a that calculates a position deviation which is a difference between a command value of the reticle stage (R stage) position from the control device 42 and a measurement value of the reticle interferometer 30.
The control operation is performed by using this position deviation as an operation signal (proportional + integral) to calculate a control amount such that the position deviation becomes zero, and the reticle stage 2 is controlled via a linear motor (not shown).
And a stage control system 48b that applies thrust to the motor 7. Although not shown, a speed control loop is set in the stage control system 48b, and the entire system for controlling the reticle stage 27 is a multi-loop control system having a speed loop as an inner loop of the position loop. Has become.

Here, as described above, the speed command value is fed forward from the control device 42 to the speed control loop inside the stage control system 48b, and the speed of the PI controller constituting the speed control loop is controlled. At the output end, a command value of the acceleration from the control device 42 is converted into a thrust and input in a feedforward manner. As described above, in addition to the control by the position loop based on the position command value, the speed command value and the acceleration command value are fed from the control device 42 to the reticle stage control circuit 48 in a feed-forward manner. In the exposure apparatus, since the speed control of the stage is the most important, the purpose is to improve the position control response of the entire system in order to achieve both the position control and the speed control.

Further, in this embodiment, an acceleration signal (information of vibration) in the XY two-degree-of-freedom direction in the fixed mirror 44 is given as a feedback signal to the reticle stage control circuit 48 from the above-described fixed mirror reference arithmetic circuit 54. The acceleration signal is fed back to the speed control loop inside the stage control system 48b via the integrator 48c, and the output of the integrator 48c is
The signal is fed back to the adder 48a of the position control loop via 8d. The reason why the acceleration signal in the XY2 degrees of freedom direction in the fixed mirror 44 is provided as a feedback signal to the position control loop and the speed control loop constituting the control system of the reticle stage 27 is as follows.

As described above, since the position of the reticle R is measured by the reticle interferometer 31 with reference to the position of the fixed mirror 44, the XY vibration of the fixed mirror 44 is given to the reticle stage control circuit 48. By that
The reticle stage control circuit 48 controls the movement of the reticle stage 27 so as to eliminate the error even if there is a residual vibration to be described later in the exposure apparatus main body 40 and there is a measurement error caused by the vibration. Will do. Accordingly, even when the vibration is in the XY directions, the position where the pattern of the reticle R is transferred to the wafer W does not change.

Further, the wafer stage control circuit 50 includes:
Although not shown, a subtractor that calculates a position deviation, which is a difference between the position command value (XY2 degrees of freedom) from the control device 42 and the wafer interferometer 31, uses this position deviation as an operation signal (proportional + integral). A) a control unit that performs a control operation, calculates a control amount such that the positional deviation becomes zero, and applies a thrust to the wafer stage 20 via a linear motor (not shown). In the speed control loop in the stage control system, feed-forward of the speed command value to the X stage 20X and the Y stage 20Y is performed.
The acceleration command values for the stages 20X and Y stage 20Y are converted into thrust and fed to the output end of a PI controller constituting a speed control loop by feedforward input.

The counter force calculation circuit 52
In order to generate a force (counter force) in a direction opposite to the fluctuation of the exposure apparatus body 40 in the six degrees of freedom in each actuator, the actuator performs a calculation and feed-forward-inputs it to the actuator control circuit 11. As shown in FIG. 3, the counter force calculation circuit 52 adds the command values of the positions of the reticle stage 27 and the wafer stage 20 from the control device 42, adjusts the gain, and further adjusts the ratio of the force applied to each actuator. First to calculate
And a matrix operation circuit (hereinafter, referred to as a "first matrix operation circuit") 52A for the sum and gain of the reticle stage 27 and the wafer stage 20. A second sum and gain matrix operation circuit (hereinafter, referred to as a "second matrix operation circuit") 52B for calculating the ratio of force.

The first matrix operation circuit 52A obtains the influence of the change in the center of gravity due to the stage movement based on the position command value of the stage (R stage 27, X stage 20X, Y stage 20Y), and cancels this. Calculate the counterforce command value. Further, the second matrix operation circuit 52B calculates a reaction force due to the acceleration based on the instruction value of the acceleration of the stage and calculates a counterforce instruction value for canceling the reaction force. The counterforce command values calculated by the matrix calculation circuits 52A and 52B are fed forward to an adder 11h constituting the actuator control circuit 11.

As shown in FIG. 3, the actuator control circuit 11 outputs a signal from the target position output unit 11a.
The target position in the direction of freedom (here, the origin (0, 0, 0,
(0,0,0) is the target position) and the acceleration signal in the 6-degree-of-freedom direction at the center of gravity G of the exposure apparatus body 40 calculated by the calculation circuit 54A based on the center of gravity of the vibration control calculation circuit 54. , 11c for calculating a position deviation (a direction of six degrees of freedom) which is a difference from the position information integrated twice, and using the position deviation output from the subtractor 11d as an operation signal (proportional + integral + differential) A) a PID control circuit 11e for performing a control operation to calculate a speed command value (six degrees of freedom), and a speed command value from the PID control circuit 11e and the center of gravity of the exposure apparatus main body 40 calculated by the center-of-gravity-based calculation circuit 54A. A subtracter 11f for calculating a speed deviation (six degrees of freedom) which is a difference between the acceleration signal in the six degrees of freedom at the position G and the speed information (six degrees of freedom) integrated by the integration circuit 11b; A PID control circuit 11g that performs a control operation (proportional + integral + differential) using the speed deviation output from the subtracter 11f as an operation signal to calculate a force command value for each actuator, and a force ID from the PID control circuit 11g. And an adder 11h to which a command value is input. As described above, the command value of the counter force from the matrix operation circuits 52A and 52B is also fed-forward input to the adder 11h.

Next, the operation of the projection exposure apparatus 100 configured as described above during scanning exposure will be described.

In the projection exposure apparatus 100, when performing exposure, a predetermined slit-shaped illumination area on the reticle R (this illumination area is illuminated by exposure illumination light EL from an illumination optical system (not shown)). (Defined by blinds in the optical system) are illuminated with uniform illumination. In synchronization with the reticle R being scanned in the predetermined scanning direction with respect to the illumination area, the wafer W is scanned with respect to an exposure area conjugate with respect to the illumination area and the projection optical system PL. As a result, the illumination light EL transmitted through the pattern area of the reticle R is reduced to a predetermined magnification by the projection optical system PL and is irradiated onto the wafer W coated with the resist, and the pattern of the reticle R is exposed on the exposure area on the wafer W. Are sequentially transferred, and the entire surface of the pattern area on the reticle R is transferred to the shot area on the wafer W by one scan.

In the step-and-scan type projection exposure apparatus 100, the controller 42 scans the reticle stage 27 in the Y direction at a speed βV (1 / β: And a signal of a command value for synchronously scanning the wafer stage 20 in the −Y direction at a speed V is output to each stage control circuit 4.
8 and 50. Each stage control circuit 4
In steps 8 and 50, the reticle stage 27 and the wafer stage 20 are controlled to scan at a predetermined position and a predetermined speed while monitoring the measurement values of the interferometers 31 and 30.

In this case, reticle stage 27
And the wafer stage 20 are scanned by the linear motor as described above, so that the acceleration and deceleration of the movement of the reticle stage 27 and the wafer stage 20 produce a reaction force on the linear motor, and the reaction force Vibration occurs in the main body 40. Also, reticle stage 27
When the wafer stage 20 is scanned, the center of gravity of the exposure apparatus main body 40 fluctuates, so that the exposure apparatus main body 40 is slightly tilted, and the exposure apparatus main body 40 vibrates.

However, in this embodiment, as described above, the counterforce calculation circuit 52 controls the reticle stage 27 and the wafer stage 20 based on the command values of the position and acceleration from the control device 42, and the influence of the change in the center of gravity due to the stage movement. And a counterforce command value for canceling the reaction force due to acceleration are calculated, and are sent to the actuators (7A to 7D, 32A to 32D) via the actuator control circuit 11. Given in feed forward. Therefore, the reaction force generated by acceleration and deceleration of the reticle stage 27 and the wafer stage 20 is basically canceled out by the force generated by each actuator driven according to the counterforce command value, and the above-described scanning of the stage is performed. Most of the vibration of the exposure apparatus main body 40 caused by the vibration is removed. However, not all the reaction forces are exactly canceled out by the counterforce, so that the exposure apparatus main body 40 has minute vibrations (hereinafter, referred to as X, Y, Z, Xθ, Yθ, and Zθ directions) in the directions of six degrees of freedom. (Referred to as residual vibration).

The fluctuation of the exposure apparatus main body 40 due to the residual vibration is caused by the six acceleration sensors 5X ₁ , 5X ₂ , 5Y ₁ , 5Y ₂ , 5Z attached to the surface plate 6 of the exposure apparatus main body 40.
₁ and 5Z ₂ respectively. These six acceleration sensor _{5X 1, 5X 2, 5Y 1} , 5Y 2, 5Z 1, 5Z
Based on the output of ₂ , the arithmetic circuit 54A based on the center of gravity in the vibration control circuit 54 performs a predetermined matrix operation to obtain a value of 6 at the center of gravity G of the exposure apparatus body 40.
The vibration in the direction of freedom is determined, and the vibration in the direction of six degrees of freedom is
Further, a matrix operation to be shared among the eight actuators is performed, and each actuator is given a feedback signal via the actuator control circuit 11. Therefore, each actuator is controlled by the actuator control circuit 11 based on the feedback signal,
The above-mentioned residual vibration is promptly suppressed. In this case, in the present embodiment, vibrations in the directions of six degrees of freedom at the center of gravity G of the exposure apparatus main body are obtained based on the values of the acceleration sensor, and a feedback signal for suppressing the vibrations in the directions of six degrees of freedom is obtained. Since the value is given to the actuator, the residual vibration can be more effectively suppressed, unlike a method in which the value of the acceleration sensor is simply fed back to the actuator disposed at the opposite position.

However, in the present embodiment, high-precision exposure can be performed even before the residual vibration is completely suppressed. That is, as described above, the six acceleration sensors 5X ₁ , 5X ₂ , 5Y ₁ ,
A fixed mirror-based calculation circuit 54B is provided for performing a predetermined matrix calculation based on the outputs of 5Y ₂ , 5Z ₁ , and 5Z ₂ to obtain vibration in two degrees of freedom in the XY directions with respect to the fixed mirror 44. The operation circuit 54B
Since the vibration in the XY2 degrees of freedom direction at the position of the fixed mirror 44 calculated in the above is fed back to the reticle stage control circuit 48, the reticle stage control circuit 4
8 controls the reticle stage 27 in consideration of this vibration _. Therefore, even if the vibration is in the XY directions,
The position where the pattern of the reticle R is transferred to the wafer W does not change.

As described above, according to the projection exposure apparatus 100 of the present embodiment, the six acceleration sensors 5X ₁ , 5X
Based on the outputs of X ₂ , 5Y ₁ , 5Y ₂ , 5Z ₁ , and 5Z ₂ , the vibration in the 6-degree-of-freedom direction at the center of gravity G of the exposure apparatus main body calculated in the vibration control arithmetic circuit 54 and the fixing for the reticle By utilizing the vibration of the mirror 44 in the two-degree-of-freedom direction, the residual vibration of the exposure apparatus main body 40, which could not be suppressed even when the counterforce was fed forward to the actuator, can be suppressed quickly. There is an effect that highly accurate exposure can be performed even if there is vibration.

In the above embodiment, the case where six acceleration sensors are provided in the exposure apparatus main body as vibration sensors has been described. However, instead of or together with this, position sensors (capacitance displacement sensors, eddy current displacement sensors) are provided. Etc.) or a speed sensor or the like may be provided as a vibration sensor.

In the above embodiment, the case where the vibration control circuit 54 obtains the vibration in the direction of six degrees of freedom at the center of gravity G of the exposure apparatus main body 40 has been described. However, the present invention is not limited to this. Instead, based on the outputs of the six acceleration sensors, the vibration control circuit 54 may determine the vibration in the directions of three degrees of freedom or six degrees of freedom at the center of the inertia main axis as the center of vibration. Here, the inertia main axis is an axis of the exposure apparatus main body in three directions that is easy to rotate.

Furthermore, in the above-described embodiment, the case has been described where the vibration control circuit 54 obtains the vibration in the two-degree-of-freedom direction in the fixed mirror 44 for the reticle based on the output of the acceleration sensor. Alternatively, a feedback signal may be given to the wafer stage control circuit by obtaining the vibration in the two-degree-of-freedom direction in the wafer fixed mirror, or the two-degree-of-freedom vibration in both the reticle and wafer fixed mirrors may be obtained. And a feedback signal may be provided to both stage control circuits.

In the above embodiment, the fixed mirror 4 fixed to the outer peripheral surface of the projection optical system PL by the vibration control circuit 54 is used.
The case where the vibration in the direction of two degrees of freedom is obtained at the position 4 has been described. However, the installation location of the third reflecting mirror (fixed mirror) is
The present invention is not limited to this, and the present invention is fully effective regardless of where the vibration of the exposure apparatus main body affects the measurement value of the interferometer.

Although the above embodiment has been described with reference to the case where the present invention is applied to a step-and-scan type projection exposure apparatus, the scope of the present invention is not limited to this. The present invention is applicable as long as one moving stage is mounted on the exposure apparatus main body. For example, the present invention can be suitably applied to a step-and-repeat type reduction projection exposure apparatus (so-called stepper).

Further, in the above-described embodiment, a case has been described in which the side surfaces of the wafer stage and the reticle stage are mirror-finished to form a reflection surface. However, the present invention is not limited to this. Of course, it may be provided separately.

[0061]

As described above, according to the first and second aspects of the present invention, it is possible to perform high-precision exposure even when residual vibration is present in the exposure apparatus main body. effective.

According to the third aspect of the present invention, in addition to the above effects, there is an effect that the residual vibration can be suppressed more quickly.

[Brief description of the drawings]

FIG. 1 is a schematic perspective view showing a projection exposure apparatus according to one embodiment.

FIG. 2 is a diagram illustrating a configuration of a vibration control system for an exposure apparatus main body.

FIG. 3 is a diagram illustrating a detailed configuration of each unit in FIG. 2;

[Explanation of symbols]

_{5Z 1, 5Z 2, 5Y 1} , 5Y 2, 5X 1, 5X 2 acceleration sensor (vibration sensor) 7A-7D actuator 11 actuator control circuit (drive control means) 20 wafer stage (second stage) 20a, 20b reflecting surface ( 27) Reticle stage (first stage) 27a, 27b Reflecting surface (first reflecting mirror) 30X, 30Y Wafer interferometer (interferometer) 31X, 31Y Reticle interferometer (interferometer) 32A-32D Actuator 40 Exposure Apparatus body 42 Control device (stage movement signal output means) 44, 46 Fixed mirror (third reflecting mirror) 48 Reticle stage control circuit (stage control means) 52 Counter force calculation circuit (counter force calculation means) 54 Vibration control calculation Circuit (Calculation means for vibration control) 100 Projection exposure apparatus R Retic (Mask) PL projection optical system W wafer (substrate)

Claims (3)

[Claims] 1. A projection exposure apparatus for transferring a pattern of a mask mounted on a first stage onto a substrate mounted on a second stage via a projection optical system, wherein the first stage and the first Stage movement signal output means for outputting a movement signal for at least one of the two stages; stage control means for controlling the stage based on the movement signal; exposure apparatus having the first and second stages mounted thereon A vibration sensor for detecting vibration of the main body; and at least one vibration sensor provided on the exposure apparatus main body.
Two actuators; drive control means for controlling the drive of the actuator so as to suppress vibration of the exposure apparatus main body; and calculating a counterforce for fluctuation of the exposure apparatus main body based on the movement signal, Counter-force calculating means for feed-forward input to the control unit; based on the detection result of the vibration sensor,
An actuator drive feedback signal to be provided to the drive control means, and a vibration control calculation means for calculating a stage feedback signal to be provided to the stage control means so that the position at which the pattern is transferred to the substrate does not change. Projection exposure apparatus having 2. A first reflecting mirror provided on the first stage, a second reflecting mirror provided on the second stage, and a third mirror fixed to a fixed portion outside the stage of the exposure apparatus main body. A reflecting mirror, and an interferometer that irradiates the first reflecting mirror or the second reflecting mirror and the third reflecting mirror with light to measure a position of the first stage or the second stage, The vibration control calculation means calculates a vibration state of the third reflecting mirror position in a two-dimensional direction in a horizontal plane, and uses the vibration state for controlling at least one of the first stage and the second stage. 3. The projection exposure apparatus according to claim 1, wherein feedback is provided to a means. 3. The vibration control calculating means calculates a vibration state in a direction of three or more degrees of freedom at a vibration center of the exposure apparatus main body and feeds back the vibration state to the drive control means. The projection exposure apparatus according to claim 1 or 2, wherein