JP2004100953A - Vibration damping device exposure device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve damping effect against floor vibration for an active type damping device and exposure device and an exposure device provided with the damper controlling the driving of a controlling object by an actuator to cancel vibration generated on the controlling object. <P>SOLUTION: A feedforward control system 200 compensates a vibration damping system of an exposure device main body based on an output of acceleration sensors 18 instantaneously detecting acceleration of a vibrational component transmitted from a floor face F. A disturbance observer 201 estimates a virtual command value from the vibrational component of the exposure device main body, regards the difference between a command value to voice coil motors 311, 12 and the virtual command value as an estimated disturbance, and corrects the command value based on the estimated disturbance. <P>COPYRIGHT: (C)2004,JPO

Description

The present invention relates to a vibration damping device and an exposure apparatus, and more particularly, to an active vibration damping device that drives and controls a control target by an actuator so as to cancel vibration generated in the control target, and includes the vibration damping device. The present invention relates to an exposure apparatus.

2. Description of the Related Art Conventionally, in a lithography process for manufacturing a semiconductor element, a liquid crystal display element, or the like, a pattern formed on a mask or a reticle (hereinafter, collectively referred to as a “reticle”) is coated with a resist or the like via a projection optical system. And repeat type reduction projection exposure apparatus (so-called stepper) for transferring onto a substrate such as a wafer or a glass plate (hereinafter collectively referred to as “wafer”), and a step and 2. Description of the Related Art A sequential movement type projection exposure apparatus such as a scanning type projection exposure apparatus (a so-called scanning stepper) is mainly used.

In this type of exposure apparatus, it is important that the positional relationship between the projection optical system, the wafer, and the reticle is appropriate, and these positional relationships are the main factors that determine the exposure performance. Therefore, in any of the stepper and the scanning stepper, the positional relationship between the projection optical system, the reticle stage on which the reticle is mounted, and the wafer stage on which the wafer is mounted is determined by an optical displacement sensor (for example, An interferometer, a synchronous detection optical system, or the like) is used, and based on the measurement result, the projection optical system is aligned with the reticle and the wafer with high accuracy.

振動 In order to realize the above-described highly accurate alignment, it is necessary to isolate the vibration component transmitted to the projection optical system, the wafer stage, and the reticle stage from the vibration source. Such vibration factors (vibration sources) include (a) dark vibration (fine vibration) on the floor of a clean room where the exposure apparatus is installed, and (b) reaction force generated by driving a stage in the exposure apparatus to the floor. In particular, when the floor rigidity is weak, the reaction force causes the floor surface to vibrate, and the vibration returns from the floor surface to the exposure apparatus and causes vibration of the exposure apparatus. The reaction force generated when the stages are driven is caused by vibrating the surface plate on which the guide surfaces of the stages are formed, and the vibration transmitted to the projection optical system via the body of the exposure apparatus and the cable connected to the stage And vibration from wiring and the like.

In the exposure apparatus, each part of the body is supported by an anti-vibration mechanism in order to prevent or suppress transmission of the various vibrations to the projection optical system, the wafer stage, and the reticle stage. Such an anti-vibration mechanism often supports the object to be supported at three or four points. For example, if it is an anti-vibration mechanism that supports the exposure apparatus itself, it is an anti-vibration mechanism that exerts an anti-vibration effect in six directions of freedom (X, Y, Z, θx, θy, θz). It is desirable. This is because when the floor or the device itself is considered as an elastic body rather than a rigid body, even if the vibration direction of the vibration transmitted to that part is fixed, the vibration varies depending on the vibration mode of the elastic body. This is because there is a possibility that the vibration is converted into a vibration in a different direction.

In recent years, such an anti-vibration mechanism includes an actuator such as an air mount or a voice coil motor capable of controlling the internal pressure, and performs feedback control based on measurement values of, for example, six accelerometers attached to each part of the body, An active vibration damping device that controls the vibration of each part of the body by controlling the thrust of a voice coil motor or the like has been adopted.

As described above, the main cause of the vibration generated in the projection optical system, the wafer stage, and the reticle stage is vibration transmitted from the floor on which the exposure apparatus is installed, that is, so-called floor vibration. The floor vibration is transmitted from the floor to a base member supporting the vibration isolating mechanism, and transmitted to each part of the body of the exposure apparatus via the vibration isolating mechanism. The active vibration damping device of the vibration isolation mechanism operates so as to actively cancel the vibration component only after the vibration component transmitted to each part of the body is detected by the above-described accelerometer or the like. That is, in the conventional active vibration damping device, the vibration transmitted from the floor is suppressed only by the feedback control that feeds back a measurement value of an accelerometer or the like provided in each part of the body. It is generally known that a feedback control system is a control system in which a certain degree of control delay occurs with respect to a disturbance component, and a feedback component that feeds back a vibration component generated in each part of the body, that is, an acceleration as a control amount. In a conventional active vibration suppression device that performs vibration suppression control only by a control system, there is a limit to suppression of vibration generated in a control target due to floor vibration.

Further, as described above, there are various sources of vibration components transmitted to the projection optical system, the wafer stage, and the reticle stage, and the disturbance components transmitted from all these vibration sources are attached to the body. It is very difficult to effectively remove or suppress only with a feedback control system based on the output of the accelerometer. Such a disturbance component that is difficult to remove or suppress becomes a factor that lowers the control level of the control system.

The present invention has been made under such circumstances, and a first object of the present invention is to provide a vibration damping device capable of improving a vibration damping effect of disturbance vibration.

Another object of the present invention is to provide an exposure apparatus capable of realizing highly accurate exposure.

According to the first aspect of the present invention, there is provided an actuator (for example, 311A or the like) that supports a control target and can be driven in a vertical direction; A vibration control system (50, 50 ') for calculating a command value to be given to the actuator based on a vibration component measured by the vibration measuring device in order to suppress vibration generated in the control object; The vibration control system is a vibration damping device that performs feedforward control based on a vibration component measured by the vibration measuring device.

According to this, the vibration control system performs the vibration suppression control of the control target based on the vibration component transmitted from the floor measured by the vibration measuring device. This makes it possible to quickly measure the vibration component generated on the floor surface and execute the vibration suppression control by the vibration control system based on the measured vibration component. The effect can be improved.

In this case, the vibration control system performs feedforward control based on the vibration component measured by the vibration measurement device. Note that the vibration measuring device may be any device that can detect a vibration component of floor vibration, such as an acceleration sensor or a displacement sensor.

In the vibration damping device according to the first aspect, like the vibration damping device according to the second aspect, it is possible to further include a member that supports the actuator and is provided with the vibration measuring device.

In this case, as in the vibration damping device according to claim 3, the vibration measuring device is provided within a range in which a portion of the member between the vibration measuring device and the actuator can be regarded as a rigid body. be able to.

According to this, since the space between the vibration measuring device and the actuator can be regarded as a rigid body, not an elastic body, the vibration component measured by the vibration measuring device is converted into a vibration component transmitted to each actuator. Becomes easier.

In the vibration damping device according to any one of claims 1 to 3, as in the vibration damping device according to claim 4, the vibration control system performs a secondary operation on a vibration system including the control target and the actuator. The command value can be calculated by approximating the model.

In this case, like the vibration damping device according to claim 5, the vibration control system converts a vibration component measured by the vibration measuring device into a vibration component at a position where the actuator is installed (91). Can be provided.

In this case, as in the vibration damping device according to claim 6, the vibration control system inputs a vibration component converted by the coordinate conversion system and calculates a vibration component transmitted to the control target. It may further include a secondary filter (92) for outputting.

In this case, the vibration control system converts the vibration component output from the secondary filter into a vibration component transmitted to the position of the center of gravity of the controlled object. A coordinate transformation system (93) may be further provided.

According to this, the vibration component measured by the vibration measuring device is converted into a vibration component immediately below the actuator by coordinate conversion, and the vibration component is input to a secondary filter that models a vibration system including the control target and the actuator. Thus, the magnitude of the vibration component generated in each actuator can be obtained. Then, the vibration component generated in each actuator is converted into the vibration component at the position of the center of gravity of the control target by the coordinate conversion. Therefore, in the vibration damping device according to the seventh aspect of the invention, the vibration component transmitted to the position of the center of gravity of the control target supported by the actuator can be extracted based on the vibration component measured by the vibration measuring device. Become like

Further, in the vibration damping device according to any one of claims 1 to 7, as in the vibration damping device according to claim 8, a control amount obtained from the control target by the control target model (101). And a disturbance observer (201) for estimating a difference between the virtual command value estimated based on the command value and the command value as a disturbance component.

Further, in the vibration damping device according to claim 8, as in the vibration damping device according to claim 9, the vibration control system includes a non-interference controller that makes the feedforward control and the disturbance observer non-interfering. 501).

The invention according to claim 10, wherein the actuator supports the control target and is drivable in a vertical direction; and the actuator is controlled based on a control amount obtained from the control target in order to suppress vibration generated in the control target. And a vibration control system (50, 50 ') for driving and controlling the actuator by feedforward control according to the command value; and a control target model (101) for estimating the actuator based on the control amount. A disturbance observer (201) for estimating a deviation between the virtual command value and the command value as a disturbance component; and a disturbance observer estimated by the disturbance observer before the vibration control system drives and controls the actuator based on the command value. A subtractor (104) for subtracting a disturbance component from the command value; and the feedforward control. A vibration damping device comprising; the non-interference controller for decoupling the disturbance observer and (501).

According to this, the disturbance observer estimates the disturbance component by calculating the difference between the command value to the actuator and the virtual command value estimated by the model of the control target, and the subtractor calculates the difference from the command value. Subtract. Therefore, in the vibration damping device of the present invention, the command value to the actuator can be a command value in which the disturbance component applied to the vibration control system is compensated, so that the vibration damping effect of the disturbance vibration can be improved. . In addition, by providing a non-interference controller (501) for decoupling the feedforward control by the vibration control system and the disturbance observer, the desired performance of the disturbance observer can be more reliably achieved. In the vibration damping device according to the tenth aspect, the disturbance observer may be included in the vibration control system.

The invention according to claim 11 is an exposure apparatus (100) for exposing a photosensitive object (W), wherein an exposure apparatus main body for performing the exposure and at least a part of the exposure apparatus main body are controlled. And a vibration damping device according to any one of (1) to (10).

According to this, at least a part of the exposure apparatus main body is held by the vibration damping device according to any one of claims 1 to 10, so that the vibration of the exposure apparatus main body is effectively suppressed. Exposure accuracy can be maintained at high accuracy.

In this case, as in the exposure apparatus according to the twelfth aspect, it is possible to further include a passive vibration isolator (for example, 312A) that supports at least a part of the exposure apparatus main body in the vertical direction.

The exposure apparatus according to claim 11 or 12, wherein, as in the exposure apparatus according to claim 13, the exposure apparatus main body includes a first stage system including a stage for holding a mask on which a predetermined pattern is formed; A second stage system including a stage on which a photosensitive object is mounted; and a projection optical system for projecting exposure light onto the photosensitive object; wherein the vibration damping device includes the second stage system and the projection optical system. At least one of them can be a control target.

Also, in the exposure apparatus according to claim 11 or 12, as in the exposure apparatus according to claim 14, the exposure apparatus main body includes a first stage system including a stage for holding a mask on which a predetermined pattern is formed. A second stage system including a stage on which the photosensitive object is mounted, and a projection optical system for projecting exposure light onto the photosensitive object, wherein the vibration damping device controls the second stage system. And the vibration damping device having the projection optical system as a control target.

Hereinafter, an embodiment of the present invention will be described with reference to FIGS.

FIG. 1 schematically shows the overall configuration of an exposure apparatus 100 according to an embodiment of the present invention. The exposure apparatus 100 transfers a circuit pattern (predetermined pattern) formed on the reticle R via the projection optical system PL while synchronously moving a reticle R as a mask and a wafer W as a photosensitive object in a one-dimensional direction. This is a step-and-scan type scanning exposure apparatus that transfers the image onto each shot area on the wafer W, that is, a so-called scanning stepper.

The exposure apparatus 100 includes an illumination unit ILU that illuminates a rectangular slit-shaped illumination area on the reticle R with uniform illumination by exposure illumination light (hereinafter simply referred to as “exposure light”) IL as an energy beam. , A reticle stage RST for holding a reticle R, a projection optical system PL for projecting exposure light IL emitted from the reticle R onto a wafer W, and a wafer stage for holding the wafer W and freely movable in an XY plane A WST, a main body column on which a reticle stage RST, a projection optical system PL, a wafer stage WST, and the like are mounted, a support 16A, and a support 16B are provided.

The illumination unit ILU is connected to a light source (not shown) via a light transmission optical system (not shown). As the light source, for example, ArF excimer laser (output wavelength 193 nm), far ultraviolet light source such as a KrF excimer laser (output wavelength 248 nm), or F, such as ₂ vacuum ultraviolet light source such as a laser (output wavelength 157 nm) is used.

The illumination unit ILU includes an illumination system housing 2, an illuminance uniforming optical system including, for example, an optical integrator arranged in a predetermined positional relationship inside the illumination system housing 2, a relay lens, a variable ND filter, and a variable field stop (reticle). An illumination optical system including a dichroic mirror and the like (both not shown). Here, a fly-eye lens, an internal reflection type integrator (such as a rod integrator), a diffractive optical element, or the like is used as the optical integrator.

The illumination unit ILU is a slit-shaped illumination area defined by a reticle blind on the reticle R on which a circuit pattern or the like is drawn (in the present embodiment, the illumination area falls within the field of view of the projection optical system PL. A rectangular illumination area elongated in the X-axis direction around the optical axis of the projection optical system PL is illuminated by the exposure light IL with substantially uniform illuminance.

The reticle stage RST is disposed above a rectangular reticle stage base 33 that constitutes a top plate of a second column described later. As shown in FIG. 1, this reticle stage RST has a predetermined scanning direction along the upper surface of reticle stage base 33 in a predetermined scanning direction (a stroke that allows at least the entire surface of reticle R to cross exposure light IL). A reticle scanning stage 24A that is movable in the Y-axis direction (here, the direction orthogonal to the paper surface of FIG. 1) and is disposed on the reticle scanning stage 24A, and can hold the reticle R and can be finely driven in the XY plane. A fine reticle fine movement stage 24B.

More specifically, the reticle scanning stage 24A is levitated and supported above the upper surface of the reticle stage base 33 by a non-contact bearing (not shown), for example, a gas static pressure bearing through a clearance of about several μm, for example. I have. The reticle scanning stage 24A is driven in the Y-axis direction by a linear motor (not shown).

In this case, the reticle fine movement stage 24B is minutely driven in the Y-axis direction and the X-axis direction on the reticle scanning stage 24A by a voice coil motor (not shown). Further, reticle fine movement stage 24B can be slightly rotated in the θz direction (the rotation direction around the Z axis orthogonal to the XY plane). Reticle R is held on reticle fine movement stage 24B by vacuum suction or the like. Although the reticle fine movement stage 24B is finely moved with three degrees of freedom (X, Y, θz), the degree of freedom may be arbitrary, for example, four or more degrees of freedom.

On the reticle fine movement stage 24B, a total of three movable mirrors are provided, one X-axis movable mirror having a reflecting surface perpendicular to the X-axis and a pair of Y-axis movable mirrors. A fixed mirror (reference mirror) serving as a reference for position measurement of the reticle fine movement stage 24B is provided on the side surface of the lens barrel of the projection optical system PL corresponding to the three movable mirrors. Alternatively, a reticle laser interferometer (hereinafter, collectively referred to as a “reticle interferometer”) is provided on the lens barrel base 25 or the like. In FIG. 1, a combination of the moving mirror, the fixed mirror, and the laser interferometer on each axis is typically shown as a moving mirror 30, a fixed mirror Mr, and a reticle interferometer RIF. The reticle interferometer RIF irradiates the movable mirror 30 and the fixed mirror Mr with an interferometer beam (measurement beam) having a length measurement axis parallel to the target axis (either the X axis or the Y axis). The reflected light is received, and the position of the movable mirror 30 in the direction of the target axis with respect to the fixed mirror Mr, that is, the position of the reticle R in the direction of the axis is constantly detected with a resolution of, for example, about 0.5 to 1 nm. Thus, the reticle interferometer RIF can detect the position of the reticle fine movement stage 24B in the X-axis direction and the Y-axis direction.

In the Y-axis direction, the pair of laser interferometers independently detect the coordinate position of the reticle fine movement stage 24B in the Y-axis direction via a pair of Y-axis moving mirrors formed of, for example, a hollow retro-reflector. By doing so, not only the position of the reticle fine movement stage 24B in the X-axis direction and the Y-axis direction, but also the rotation direction (θz direction) of the reticle fine movement stage 24B can be detected. The measurement values of the reticle interferometer RIF are transmitted to a main controller (not shown) that controls the entire exposure apparatus 100 via a stage controller (not shown). Further, the end surface of reticle fine movement stage 24B may be mirror-finished to form a reflection surface for a laser interferometer (corresponding to the reflection surface of movable mirror 30 described above). The main controller controls the position of the reticle R in the X-axis direction, the Y-axis direction, and the θz direction based on the measurement value of the reticle interferometer RIF so that appropriate scanning exposure is performed.

フ ラ ン ジ A flange portion FLG is provided in the lens barrel of the projection optical system PL. The projection optical system PL is inserted from above into an opening 25a formed at the center of a rectangular plate-shaped lens barrel base 25 constituting a first column, which will be described later, and is mounted via a flange FLG. Three points are supported on the board 25.

As the projection optical system PL, for example, a dioptric system composed of a plurality of lens elements having a common optical axis in the Z-axis direction, which is a telecentric reduction system on both sides, is used. The projection magnification of the projection optical system PL is, for example, 1/4, 1/5 or 1/6. Therefore, when the above-described illumination area on the reticle R is illuminated by the exposure light IL from the illumination unit ILU, a reduced image (partially inverted image) of the circuit pattern in the illumination area of the reticle R via the projection optical system PL. Are formed in a slit-shaped projection area conjugate to the illumination area, that is, an exposure area, which is an area on the wafer W having a surface coated with a photoresist.

The wafer stage WST is arranged on a rectangular plate-shaped wafer stage base 29 arranged below the lens barrel base 25, as shown in FIG. Wafer stage WST is movable in the XY plane while holding wafer W.

The wafer stage WST includes, for example, an XY stage 14 that is freely driven in an XY plane by a wafer stage driving unit (not shown) including a linear motor or a two-dimensional linear actuator of an air levitation type or a magnetic levitation type. A wafer table TB mounted on the XY stage 14. A wafer holder (not shown) is fixed on the wafer table TB by vacuum suction, and a wafer W is fixed on the wafer holder via a vacuum chuck, an electrostatic chuck, and the like (not shown). Further, the XY stage 14 (or wafer table TB) can be minutely rotated also in a rotation direction (θz direction) around the Z axis.

The wafer table TB can be finely driven in the Z-axis direction and in the tilt direction with respect to the XY plane (rotation direction around the X-axis (θx direction) and rotation direction around the Y-axis (θy direction)).

An X moving mirror extends in the Y-axis direction at the -X end of the upper surface of the wafer table TB, and a Y moving mirror extends in the X-axis direction at the -Y end of the upper surface of the wafer table TB. Have been. These movable mirrors are respectively irradiated with measurement beams from a wafer laser interferometer (hereinafter abbreviated as “wafer interferometer”) suspended from and supported by a barrel base 25 of the projection optical system PL. Actually, as the wafer interferometer, a wafer X interferometer for measuring the position in the X direction and a wafer Y interferometer for measuring the position in the Y direction are provided. Corresponding to this, a wafer X fixed mirror and a wafer Y fixed mirror are provided in the lens barrel of the projection optical system PL, respectively. In FIG. These are shown as a wafer interferometer WIF, a movable mirror 34, and a fixed mirror Mw, respectively.

The position information of the wafer table TB in the X-axis direction and the Y-axis direction is constantly detected by the wafer interferometer WIF with a resolution of, for example, about 0.5 to 1 nm with respect to the above-mentioned fixed mirror. The wafer X interferometer and the wafer Y interferometer are each constituted by a multi-axis interferometer having a plurality of measuring axes, and in addition to the position of the wafer table TB in the X-axis and Y-axis directions, the rotation (yaw (around the Z-axis)). Rotation (θz rotation), pitching (θx rotation around X axis), and rolling (θy rotation around Y axis) can also be measured. Note that the end surface of the wafer table TB may be mirror-finished to form a reflecting surface (corresponding to the reflecting surfaces of the X-moving mirror and the Y-moving mirror).

(4) Position information (or speed information) of wafer stage WST measured by wafer interferometer WIF is transmitted to a main controller (not shown) via a stage controller (not shown). The stage controller basically controls the wafer interferometer WIF so that the position information (or speed information) output from the wafer interferometer WIF matches the command value (target position, target speed) given from the main controller. The movement of the wafer stage WST in the XY plane is controlled via the above-described wafer stage driving unit (not shown) based on the output of the above. That is, the main controller controls the position of the wafer W in the X-axis direction, the Y-axis direction, and the θz direction based on the measurement values of the wafer interferometer WIF, and performs the reticle interferometer RIF and the wafer interferometer WIF during scanning exposure. The reticle stage RST (reticle scanning stage 24A) and the wafer stage WST are driven synchronously based on the measured values of the reticle stage RST and the reticle stage RST so that the synchronization error between the reticle R and the wafer W becomes zero or less than an allowable value. The position of at least one of RST (reticle fine movement stage 24B) and wafer stage WST is adjusted.

Further, although not shown, the exposure apparatus 100 detects the position in the Z-axis direction (the optical axis direction of the projection optical system AL) of the portion in the exposure region on the surface of the wafer W and a region in the vicinity thereof. For example, an oblique incidence type multi-point focus position detection system disclosed in Japanese Patent Application Laid-Open No. 6-283403 is provided. The main controller performs the focus / leveling control of the wafer W based on the output of the multipoint focus position detection system at the time of scanning exposure to be described later.

As shown in FIG. 1, the main body column includes a base plate 21 placed horizontally on the floor F, a first column placed on the base plate 21, a second column placed on the first column, The wafer stage surface plate 29 and the like, which are horizontally supported by four actuator portions 38A to 38D disposed on the base plate 21 (however, the actuator portions 38C and 38D on the back side of the drawing are not shown in FIG. 1). Have.

The first column includes four support columns 23 disposed on the base plate 21 (however, two support columns 23 on the back side of the drawing are not shown in FIG. 1) and an upper surface of each support column 23. The lens barrel base (main frame) 25 is supported substantially horizontally via the actuator sections 31A to 31D.

The second column is composed of four support columns 27 arranged on the upper surface of the lens barrel base 25 so as to surround the projection optical system PL (however, in FIG. (Not shown), and the above-mentioned reticle stage base 33 supported substantially horizontally on the upper surface of each support column 27 via actuator portions 39A to 39D.

In the present embodiment, the first column has four support columns 23 and the second column has four support columns 27. However, the support columns 23 and 27 are respectively The number may be three. Also in this case, the lens barrel base 25 and the reticle stage base 33 can be stably supported by the three-point support. Further, although the wafer stage base 29 is supported by the four actuators 38A to 38D, three actuators may support the wafer stage base 29 at three points. Further, in the present embodiment, three sets of actuator units 31A to 31D, 38A to 38D, and 39A to 39D that support the lens barrel base 25, the wafer stage base 29, and the reticle stage base 33 are each provided with an air mount or the like. It is assumed that the anti-vibration mechanism has a vibration pad and an actuator such as a voice coil motor (the detailed configuration thereof will be described later).

加速度 On the upper surface of the lens barrel base 25, three acceleration sensors 17A to 17C such as semiconductor acceleration sensors are installed. However, FIG. 1 does not show the actuator 17C on the far side of the drawing. In addition, acceleration sensors 18A to 18D as vibration measuring devices are provided on the upper surface of the base plate 21 and near the support columns 23, respectively. The acceleration sensors 18A to 18D are sensors that measure acceleration due to vibration transmitted from the floor F side, that is, a vibration component of floor vibration. The acceleration sensors 18A to 18D need to be provided within a range in which a portion (base plate 21 and support column 23) between any of the actuator sections 31A to 31D and each acceleration sensor can be regarded as a rigid body. Therefore, the acceleration sensors 18A to 18D may be provided on the support columns 23 as long as they can be mounted. The acceleration sensors 18A to 18D detect the acceleration in the Z-axis direction at each installation position as a vibration component.

支 The columns 16A and 16B are arranged on the base plate 21 so as to sandwich the main body column in the X-axis direction. A support 16D (not shown in FIG. 1, see FIG. 3) is arranged on the back side of the support 16A, and a support 16C (not shown in FIG. 1, see FIG. 3) on the back side of the support 16B. Is arranged.

可 動 Furthermore, a movable shaft 15A is attached to a side surface of the lens barrel base 25 in the −X direction. The voice coil motor 12A is attached to the support 16A, and can apply a force to the movable shaft 15A in the + Y direction or the −Y direction. On the support 16A, a pneumatic actuator 13A is installed in parallel with the voice coil motor 12A. The pneumatic actuator 13A can apply a force in the + Y direction or the −Y direction to the movable shaft 15A, similarly to the voice coil motor 12A.

A voice coil motor 12B and a pneumatic actuator 13B are attached to the support 16B in parallel, and the movable shaft 15B attached to the + X side of the lens barrel base 25 in the + Y direction or the −Y direction. A force can be applied in the direction.

In the exposure apparatus 100, the vibration system (second stage system) based on the wafer stage base 29 and the vibration system including the projection optical system PL are mechanically separated. The vibration generated by the movement of wafer stage WST is not directly transmitted to projection optical system PL. By adopting such a structure, it is possible to maintain the exposure accuracy with high accuracy.

露 光 In the exposure apparatus 100 of the present embodiment configured as described above, the exposure operation is performed as follows.

First, under control of a main controller (not shown), a reticle load and a wafer load are performed by a reticle loader and a wafer loader (not shown). Then, a reticle alignment system (not shown) for detecting an alignment mark of reticle R and a reference mark (not shown) of reticle stage RST, and an alignment mark on wafer W and a reference mark (not shown) of wafer stage WST are detected. Preparation work such as reticle alignment and baseline measurement using an off-axis type alignment detection system (not shown) is performed in a predetermined procedure.

After that, the main controller performs alignment measurement such as EGA (Enhanced Global Alignment) using an alignment detection system (not shown). In such an operation, when the movement of the wafer W is necessary, the main controller moves the wafer stage WST holding the wafer W in a predetermined direction via a stage controller (not shown). When the alignment measurement is completed, the exposure operation of the step-and-scan method is performed as follows.

In this exposure operation, first, wafer stage WST is moved so that the XY position of wafer W becomes the scanning start position (acceleration start position) for exposure of the first shot area (first shot) on wafer W. Is done. At the same time, the reticle stage RST is moved such that the XY position of the reticle R becomes the scanning start position (acceleration start position). Then, based on an instruction from the main control device, the stage control device controls the reticle R based on the XY position information of the reticle R measured by the reticle interferometer RIF and the XY position information of the wafer W measured by the wafer interferometer WIF. Scanning exposure is performed by synchronously moving the wafer W.

(5) When the transfer of the reticle pattern to one shot area is completed in this way, wafer stage WST is stepped by one shot area, and scanning exposure is performed for the next shot area. In this manner, the stepping and the scanning exposure are sequentially and repeatedly performed, and the required number of shot patterns are transferred onto the wafer W.

Next, as for the actuator units provided at various parts of the exposure apparatus 100, the actuator unit 31A, which is one of the four actuator units 31A to 31D supporting the lens barrel base 25, is representatively shown. 2 will be described in detail.

FIG. 2 schematically shows an example of the actuator section 31A. The actuator unit 31A shown in FIG. 2 has an air mount unit 312A supporting the lens barrel base 25 and the lens barrel base 25 in the direction of gravity (vertical direction: the vertical direction in the plane of the paper in FIG. 2 (Z direction shown in FIG. 1). (Axial direction)) and a voice coil motor 311A capable of minute driving with high response. The voice coil motor 311A is connected to a current supply source 375.

The air mount portion 312A is provided with a housing 361 having an opening at an upper portion, a holding member 362 provided to close the opening of the housing 361, and holding the lens barrel base 25, and connected to the housing 361 and the holding member 362. The housing 361 and the holding member 362 are provided with a diaphragm 363 that forms a gas chamber 369 in a substantially airtight state. The air mount 312A is connected to the electromagnetic regulator 355.

The electromagnetic regulator 355 is a regulator that can adjust the pressure of a gas, for example, air, which is charged into the gas chamber 369 from outside via a pipe (not shown). By adjusting the air pressure by the electromagnetic regulator 355, the air mount unit 312A is configured to be able to actively follow low-frequency vibrations up to about 20 Hz. Note that the electromagnetic regulator 355 adjusts the air pressure of the gas chamber 369 according to an instruction from a control device described later. The air mount unit 312A also operates as a passive vibration isolator (vibration isolating pad) that absorbs a high-frequency vibration component that cannot be followed by a voice coil motor 311A described later.

The voice coil motor 311A drives the lens barrel base 25 in the direction of gravity by electromagnetic interaction generated between the mover 374a directly attached to the lens barrel base 25 and the mover 374a. And a stator 374b for generating a force. The current supply source 375 is a power supply for supplying a drive current to the voice coil motor 311A, and adjusts a current supplied to the stator 374b of the voice coil motor 311A according to an instruction from a control device described later. With this adjustment, the voice coil motor 311A can actively follow the vibration having a frequency higher than about 20 Hz. In the present embodiment, the actuator 311A can also correct the inclination of the lens barrel base 25 due to the change in the center of gravity (eccentric load) caused by the movement of the reticle stage RST or the wafer stage WST. As the actuator 311A for slightly moving the lens barrel base 25 in the direction of gravity, an EI core or the like other than the voice coil motor may be used.

As described above, the actuator unit 31A is configured by a combination of the so-called voice coil motor 311A and the air mount unit 312A that is a pneumatic actuator, and the actuator units 31B to 31D are configured similarly to the actuator unit 31A. (These voice coil motors and air mounts are referred to as voice coil motors 311B to 311D and air mounts 312B to 312D, respectively). In the present embodiment, the actuator units 38A to 38D inserted between the wafer stage base 29 and the base plate 21 and the actuator units 39A to 39A inserted between the reticle stage base 33 and the support columns 27, respectively. 39D is configured similarly to the actuator section 31A. The above-described voice coil motors 12A and 12B have the same configuration as the voice coil motor 311A shown in FIG. 2, and can be driven by adjusting the driving current supplied from each current supply source. The pneumatic actuators 13A and 13B also have the same configuration as the air mount 312A shown in FIG. 2, and can be driven by adjusting their respective electromagnetic regulators.

FIG. 3 is a sectional view taken along line A-A ′ in FIG. 1. As shown in FIG. 3, the rectangular plate-shaped lens barrel base 25 supporting the projection optical system PL via the flange portion FLG has actuator portions 31A to 31D arranged at four corners on the lower surface side thereof. Supported by As described above, the four support columns 27 are disposed on the upper surface of the lens barrel base 25 so as to be located at the four corners of the lens barrel base 25, and the acceleration sensors 17 </ b> A to 17 </ b> A 17C is installed.

The acceleration sensor 17A detects the X-axis direction of the acceleration (the acceleration component and AX ₁₎ together with the Z-axis direction of the acceleration (the acceleration component and AZ _1). The acceleration sensors 17B and 17C detect acceleration in the Y-axis direction (the respective acceleration components are AY ₁ and AY ₂ ) and acceleration in the Z-axis direction (the respective acceleration components are AZ ₂ and AZ ₃ ). Therefore, these acceleration sensors 17A-17C, 6 single acceleration components generated in the lens barrel base _{25 (AX 1, AY 1,} AY 2, AZ 1, AZ 2, AZ 3) is detected. Figure as indicated by the dotted line in 3, acceleration components detected by the acceleration sensor _{17A~17C (AX 1, AY 1,} AY 2, AZ 1, AZ 2, AZ 3) , the control device 50 as a vibration control system Sent to.

A voice coil motor 12C having the same configuration as the voice coil motor 12A and a pneumatic actuator 13C having the same configuration as the pneumatic actuator 13A are arranged in parallel between the side surface in the + X direction of the lens barrel base 25 and the support 16C. Installed. These two actuators 12C and 13C can apply a force to the lens barrel base 25 in the + X direction or the −X direction. The voice coil motor 12C and the pneumatic actuator 13C can also be driven by adjusting a current supply source and an electromagnetic regulator, which are respective driving devices.

As shown by the solid line in FIG. 3, a control signal for controlling the electromagnetic regulator for the pneumatic actuator 13C that adjusts the pressure of the air to be pressurized is supplied from the control device 50 to the pneumatic actuator 13C. Have been. Further, between the side surfaces in the -X direction of the lens barrel base 25 and the column 16D, opposing surfaces are provided with magnetizing bodies 37A and 37B having the same polarity, and are pneumatically operated by the repulsive force of the magnetizing bodies 37A and 37B. The actuator 13C is pressed in the + X direction. Similarly, the actuator 13B is pressed in the −Y direction by the magnet units 35A and 35B having the same polarity disposed between the support 16C and the movable shaft 15B. Further, the pneumatic actuator 13A is pressed in the -Y direction by magnets 36A and 36B of the same polarity disposed between the support 16D and the movable shaft 15A.

Therefore, in the present embodiment, the vibration in the X-axis direction of the lens barrel base 25 is suppressed by the pneumatic actuator 13C and the voice coil motor 12C, and the first Y-axis of the pneumatic actuator 13A and the voice coil motor 12A is suppressed. The vibration of the lens barrel base 25 in the Y-axis direction is suppressed by the actuator. Further, the rotation direction of the lens barrel base 25 around the Z axis is performed by the cooperative operation of the second Y axis actuator including the pneumatic actuator 13B and the voice coil motor 12B and the first Y axis actuator. Is suppressed. That is, mirrors are formed by these three sets of actuators ((12A, 13A), (12B, 13B), (12C, 13C)) and four sets of actuator sections 31A to 31D arranged on the bottom surface of the barrel base 25. Six degrees of freedom vibration of the cylinder platen 25, which includes three degrees of freedom in the translational direction and three degrees of freedom in the rotational direction, is suppressed. In the present embodiment, three sets of actuators (12A, 13A), (12B, 13B), and (12C, 13C) suppress vibration of the lens barrel base 25 in the X-axis, Y-axis, and θz directions. However, for example, by incorporating an actuator (such as a voice coil motor) for finely moving the lens barrel base 25 in at least one of the X-axis direction and the Y-axis direction into at least a part of each of the actuator units 31A to 31D, the lens barrel is similarly formed. The vibration of the platen 25 may be suppressed, and in this case, the columns 16A to 16D (including the above-described three sets of actuators) are not required.

Although not shown in FIG. 3 to avoid complicating the drawing, the displacement of the lens barrel base 25 in the X-axis direction (this displacement is expressed by X1 ) And a displacement sensor for detecting a displacement in the Z-axis direction (this displacement is referred to as Z1), a displacement of the lens barrel base 25 in the Y-axis direction (this displacement is referred to as Y1), and a displacement in the Z-axis direction ( And a displacement sensor for detecting this displacement as Z2). On the side surface of the lens barrel base 25 in the + X direction, the displacement of the lens barrel base 25 in the Y-axis direction (this displacement is defined as Y2) and the displacement in the Z-axis direction (this displacement is defined as Z3) are detected. Displacement sensor is provided.

渦 As these displacement sensors, for example, eddy current displacement sensors are used. According to this eddy current displacement sensor, an AC voltage is applied to a coil wound in advance on an insulator, and when the sensor approaches an object to be measured made of a conductive material (conductor), the AC magnetic field generated by the coil causes the conductor to generate an AC voltage. An eddy current is generated at The direction of the magnetic field generated by this eddy current is opposite to the magnetic field created by the current in the coil, and these two magnetic fields overlap each other and affect the output of the coil. That is, the intensity and phase of the current flowing through the coil change due to the action of the two magnetic fields. This change becomes larger as the measurement object is closer to the coil, and becomes smaller as the measurement object is farther from the coil. Therefore, the displacement of the measurement object can be known by extracting an electric signal from the coil.

In addition, as a displacement sensor, a capacitance type that detects the distance between the sensor and the measurement object in a non-contact manner by utilizing that the capacitance is inversely proportional to the distance between the electrode of the sensor and the measurement object. A non-contact displacement sensor may be used. If the configuration is such that the influence of the background light can be prevented, a PSD (semiconductor light position detector) can be used as the displacement sensor. From the outputs (X1, Y1, Y2, Z1, Z2, Z3) of the displacement sensors described above, it is possible to detect displacements (X, Y, Z, θx, θy, θz) of the lens barrel base 25 with six degrees of freedom. Become. The outputs (X1, Y1, Y2, Z1, Z2, Z3) of the displacement sensors are also supplied to the control device 50, similarly to the acceleration sensors 17A to 17C.

Controller 50, the output of the acceleration sensor _{17A~17C (AX 1, AY 1,} AY 2, AZ 1, AZ 2, AZ 3) and the output of the displacement sensor and (X1, Y1, Y2, Z1 , Z2, Z3) To calculate the six-degree-of-freedom vibration components generated at the position of the center of gravity of the exposure apparatus main body including the lens barrel base 25, the projection optical system PL, and the like. A command value (control signal) to be given to 31D, the pneumatic actuators 13A to 13C, and the voice coil motors 12A to 12C is calculated and output, and drive control is performed. In the voice coil motors 311A to 311D and the voice coil motors 12A to 12C of the actuator sections 31A to 31D, the magnitude of the current supplied from the current supply source is proportional to the thrust generated in the motor by the current. Therefore, the above-described command value may be a value corresponding to the magnitude of the current to be supplied from the current supply source to the voice coil motor. The command value given to the air mount units 312A to 312D of the actuator units 31A to 31D is an adjustment value of the electromagnetic regulator 355. Note that, in FIG. 3, a driving device (the above-described electromagnetic regulator 355 and the current supply source 375) of each actuator is not illustrated to avoid complicating the drawing, but a command value output from the control device 50 is Is input to the drive device of each actuator.

FIG. 4 shows at least a part of an exposure apparatus main body as a control target (here, a part including a projection optical system PL based on a barrel base 25, and in the following description, this is referred to as " A control block diagram of a vibration damping device centered on a control device 50 for controlling the vibration of the “exposure device main body” is shown. In FIG. 4, for the sake of simplicity, the above-described acceleration sensors 17A to 17C are collectively shown as an acceleration sensor group 17, and the above-described displacement sensors (not shown) are collectively shown as a displacement sensor group. The acceleration sensors 18 </ b> A to 18 </ b> D are collectively illustrated as an acceleration sensor group 18. In FIG. 4, the voice coil motors 311A to 311D of the actuator units 31A to 31D are collectively illustrated as a voice coil motor group 311. The voice coil motors 12A to 12C are collectively illustrated as a voice coil motor group 12. ing. Further, the air mount units 312A to 312D of the actuator units 31A to 31D and the pneumatic actuators 13A to 13C are collectively shown as an air mount group 13.

As shown in FIG. 4, the control device 50 performs feedback control as a control system of the voice coil motor groups 12 and 311 based on an output of the acceleration sensor group 17 and an output of the displacement sensor group 19 as control amounts. It has a control system. Further, the control device 50 includes a feedforward control system 200 that performs feedforward control based on the output of the acceleration sensor group 18 and a disturbance that estimates a disturbance component added to the feedback control system, as a compensation system of the feedback control system. And an observer 201.

This will be described in more detail. First, as shown in FIG. 4, a feedback control system in the control device 50 includes a first coordinate conversion unit 61 for inputting an output of the displacement sensor group 19 and a target value output unit 51 in a main control device (not shown). A position control system including a subtractor 62 for obtaining and outputting a deviation between a target value input from the controller and an output of the first coordinate conversion unit 61 and a position controller 63 for inputting the output of the subtractor 62, as a main loop. Prepare.

Further, in this feedback control system, a high-pass filter (hereinafter abbreviated as “HPF”) 71 for inputting the output of the acceleration sensor group 17, a second coordinate conversion unit 72 for inputting the output of the HPF 71, and a second coordinate Speed control including an integrator 73 for inputting the output of the conversion unit 72, a subtractor 74 for subtracting the output of the integrator 73 from the output of the position controller 63, a speed controller 75 for inputting the output of the subtractor 74, and the like. A system is provided as a minor loop inside the position control system. Note that the output of the speed controller 75 is finally input to the decoupling operation unit 65, and the decoupling operation unit 65 sends the output to the voice coil motor group 311 and the voice coil motor group 12 of the actuator units 31A to 31D. The command value of is output.

The control device 50 includes a control system for the pneumatic actuator in addition to the control system for the voice coil motor described above. The output of the acceleration sensor group 17 is input to a HPF 71 and also to a low-pass filter (hereinafter abbreviated as “LPF”) 81. The LPF 81 extracts a low-frequency component of, for example, 20 Hz or less from the output signal of the acceleration sensor group 17 and outputs it. The output of the LPF 81 is input to the air mount drive system 82. The air mount drive system 82 is a feedback control system that drives and controls the air mount group 13 based on a low frequency in the output of the acceleration sensor group 17, for example, a low frequency component of 20 Hz or less, and is output from the air mount drive system 82. The command value is input to the air mount group 13.

Here, the control system of the voice coil motor of the control device 50 will be described in detail. First, the first coordinate conversion unit 61 converts the outputs (X1, Y1, Y2, Z1, Z2, Z3) of the displacement sensor group 19 into displacements (X, Y, Z) of the center of gravity of the exposure apparatus main body with six degrees of freedom. , Θx, θy, θz), and outputs the information. In FIG. 4, the outputs (X1, Y1, Y2, Z1, Z2, Z3) of the displacement sensor group 19 are indicated by a single dotted line in order to avoid complication of the drawing. As described above, in FIG. 4, the outputs of the sensors and the outputs of the filters that remove a predetermined frequency component from the outputs, that is, the components (X, Y, Z, θx, θy, θz) of the six-degree-of-freedom system. The plurality of outputs that have not been converted to are represented by a single dotted line, and the components of the six-degree-of-freedom system output from other devices are collectively illustrated by a single solid line.

The target value output unit 51 outputs target positions (X0, Y0, Z0, θx0, θy0, θz0) having six degrees of freedom, and the subtracter 62 outputs the target positions (X0, Y0, Z0, θx0, θy0, θz0) and respective deviations (X0−X, Y0−Y, Z0−Z, θx0−) between the positions (X, Y, Z, θx, θy, θz) output from the first coordinate converter 61. θx, θy0−θy, θz0−θz) are calculated and output to the position controller 63. Note that these deviations are (ΔX, ΔY, ΔZ, Δθx, Δθy, Δθz).

The position controller 63 performs, for example, proportional-integral control (PI control) based on the input deviations (ΔX, ΔY, ΔZ, Δθx, Δθy, Δθz), and executes speed commands (VX0, VY0, VZ0, Vθx0, Vθy0, Vθz0). The position controller 63 does not need to be a controller that performs PI control, and may be a controller that performs proportional-integral-differential control (PID control), or may only perform proportional control or integral control. It may be a controller. Instead of PI control in which proportional control is compensated by integral control, a controller that performs IP control or IPD control in which integral control is compensated by proportional control may be used.

On the other hand, the output (AX ₁ , AY ₁ , AY ₂ , AZ ₁ , AZ ₂ , AZ ₃ ) of the acceleration sensor group 17 has its low-frequency component (for example, a component of about 20 Hz or less) removed by the HPF 71 and the second coordinate. It is input to the converter 72. The second coordinate conversion unit 72 converts the outputs (AX ₁ , AY ₁ , AY ₂ , AZ ₁ , AZ ₂ , AZ ₃ ) of the acceleration sensor group 17 into an acceleration component (AX) having six degrees of freedom of the center of gravity of the exposure apparatus main body. , AY, AZ, Aθx, Aθy, Aθz). The acceleration components (AX, AY, AZ, Aθx, Aθy, Aθz) are first-order integrated by the integrator 73 and are converted into velocity components (VX, VY, VZ, Vθx, Vθy, Vθz).

The subtractor 74 calculates the speed commands (VX0, VY0, VZ0, Vθx0, Vθy0, Vθz0) output from the position controller 63 and the speed components (VX, VY, VZ, Vθx, Vθy, Vθz) of the integrator 73. (ΔVX, ΔVY, ΔVZ, ΔVθx, ΔVθy, ΔVθz) are output. The speed controller 75 receives the deviations (ΔVX, ΔVY, ΔVZ, ΔVθx, ΔVθy, ΔVθz), and commands the force values (Fx, Fy, Fz, Fθx, Fθy, Fθz) to be applied to the center of gravity of the exposure apparatus main body. ) Is calculated. Note that the speed controller 75 also calculates command values (Fx, Fy, Fz, Fθx, Fθy, Fθz) by PI control or the like, similarly to the position controller 63.

This command value is input to the decoupling operation unit 65 after compensation by the feedforward control system 200 and the disturbance observer 201 described later. The decoupling calculation unit 65 performs decoupling calculation, and outputs the six degrees of freedom command values (Fx, Fy, Fz, Fθx, Fθy, Fθz) to each of the voice coil motors 311A to 311D of the voice coil motor group 311. , Are converted into command values for the voice coil motors 12A to 12C of the voice coil motor group 12, and the command values for the respective voice coil motors 311A to 311D, 12A to 12C (actually, current supply sources for those motors). (Drive device)).

The present embodiment includes the feedforward control system 200 and the disturbance observer 201 for compensating the above-described position and speed feedback control system. First, the feedforward control system 200 will be described in detail.

As shown in FIG. 4, the feedforward control system 200 includes a third coordinate converter 91, a feedforward (hereinafter abbreviated as “FF”) controller 92, a fourth coordinate converter 93, Devices 94, 95, and 96. 4, the acceleration sensors 18A to 18D are collectively shown as an acceleration sensor group 18.

加速度 The acceleration in the Z-axis direction measured by the acceleration sensors 18A to 18D is input to the control device 50 and input to the third coordinate conversion unit 91. The third coordinate conversion unit 91 converts the acceleration components measured by the acceleration sensors 18A to 18D into acceleration components in the actuator units 31A to 31D.

加速度 The acceleration components in the actuator units 31A to 31D are input to the FF controller 92.

In the present embodiment, a vibration system including the exposure apparatus main body based on the barrel base 25 and the actuator units 31A to 31D is approximated as a secondary vibration system model. Therefore, in the present embodiment, a second-order filter represented by the following transfer function G (s) is applied as the FF controller 92.

This secondary filter converts the acceleration components in the actuator units 31A to 31D into vibration components transmitted from the actuator units 31A to 31D to the exposure apparatus main unit.

In this secondary filter, Mn is the mass in this vibration system, Cn is the viscous friction coefficient, Kn is the spring constant, s is the Laplace operator, and any of A to D is substituted for n.

That is, in the FF controller 92, a secondary filter having a different mass, viscous friction coefficient, and spring constant is prepared for each of the actuator units 31A to 31D. For example, the acceleration component corresponding to the actuator unit 31A is input to a secondary filter including a mass M _A , a viscous friction coefficient C _A , and a spring constant K _A, and the acceleration components corresponding to the actuator unit 31B are mass M _B , It is input to a secondary filter consisting of a viscous friction coefficient C _B and a spring constant K _B. That is, the acceleration component of each actuator section is input to a secondary filter having different coefficients. By doing so, it is possible to set a vibration model with different control parameters for each actuator unit, and realize fine vibration control according to the characteristics of each actuator. The output of each secondary filter is input to the fourth coordinate conversion unit 93.

The fourth coordinate conversion section 93 converts the output of the secondary filter, that is, the vibration component transmitted from each of the actuator sections 31A to 31D to the exposure apparatus main body, in the Z-axis direction, θx direction, and θy direction at the center of gravity of the exposure apparatus main body. Are converted into vibration components (Fz ′, Fθx ′, Fθz ′), and output as compensation values of command values in the Z-axis direction, θx direction, and θy direction.

The outputs of the fourth coordinate conversion unit 93, that is, the vibration components (Fz ′, Fθx ′, Fθz ′) at the center of gravity of the exposure apparatus main body transmitted from the floor vibration are output from the speed controllers by the adders 94, 95, and 96. Among the command values output from 75, they are added to the corresponding command values (Fz, Fθx, Fθy) in the Z-axis direction, θx direction, and θy direction.

The decoupling calculation unit 65 converts the command values of six degrees of freedom compensated by the feedforward control system 200 as described above into command values to the actuators 311A to 311D and 12A to 12C (current command values for the current supply source). ) And output.

Next, compensation by the disturbance observer 201 will be described. The disturbance observer 201 includes an exposure apparatus main body model 101, a subtractor 102, and an LPF 103.

The output of the first coordinate conversion unit 61, that is, the displacement of the exposure apparatus main body with six degrees of freedom at the center of gravity is also input to the exposure apparatus main body model 101. The exposure apparatus main body model 101 is a model of a vibration system including the exposure apparatus main body section including the projection optical system PL and the like and the actuator sections 12A to 12D based on the lens barrel base 25. The exposure apparatus main body model 101 is configured to output an output of the first coordinate conversion unit 61, that is, a virtual command value having six degrees of freedom corresponding to a displacement of the exposure apparatus main body having six degrees of freedom.

The virtual command value output from the exposure apparatus main body model 101 is subtracted in the subtractor 102 by the actual command value before being input to the decoupling operation unit 65. This subtraction value is the estimated disturbance estimated by the disturbance observer 201. The exposure apparatus main body model 101 is desirably a model that has a small deviation from the actual exposure apparatus main body. For example, the exposure apparatus main body and the actuator are approximated as a secondary model, and the viscous friction coefficient is further increased. The transfer function (F (s) = Mn · s ² ) obtained by simplifying the calculation can be applied as the transfer function of the exposure apparatus main body model 101, assuming that both the and the spring constant are 0. In this way, the deviation between the exposure apparatus main body model 101 and the actual model of the exposure apparatus 100, that is, the component generated by the viscous friction element or the spring element is included in the estimated disturbance component of the disturbance observer 201, By the effect, the vibration generated in the exposure apparatus main body is effectively suppressed.

出力 The output of the subtractor 102, that is, the estimated disturbance, has its high-frequency component removed by the LPF 103, and the subtractor 104 subtracts from the command value input to the decoupling operation unit 65. Therefore, a command value from which the disturbance component estimated by the disturbance observer 201 has been removed is input to the decoupling calculation unit 65.

Although FIG. 4 shows only the control system that suppresses the vibration of the exposure apparatus main body including the lens barrel base by the actuator sections 31A to 31D, the portion of the exposure apparatus main body based on the reticle stage base 33 is shown. (A first stage system) is controlled by a vibration control system that drives and controls the actuator units 39A to 39D, and a part (second stage system) of the exposure apparatus main body, which is based on the wafer stage base 29, is used as an actuator unit. Needless to say, a compensation control system similar to the feedforward control system 200 and the disturbance observer 201 as shown in FIG. 4 can be applied to a vibration control device of a vibration control system that is driven and controlled by 38A to 38D. In the exposure apparatus shown in FIG. 1, the reticle stage base 33 is supported via the actuators 39A to 39D. However, the actuators 39A to 39D do not necessarily need to be used together with the actuators 31A to 31D. The actuators 31A to 31D may be provided alone without the parts 39A to 39D. In this case, the reticle stage base 33 and the lens barrel base 25 are regarded as one body, and the portions based on the lens barrel base 25 including the reticle stage base 33 are controlled by the actuator units 31A to 31D. The compensation vibration system (feed-forward control system 200, disturbance observer 201) of FIG. 4 may be applied to the control device of the vibration control system to be controlled. Further, in the exposure apparatus of FIG. 1, the lens barrel base 25 and the wafer stage base 29 are supported by different actuators 31A to 31D and 38A to 38D, respectively. The actuator units 38A to 38D may not be provided by adopting a structure in which the actuator units 38A to 38D are supported by being suspended from the board 25. In this case, at least the lens barrel base 25 and the wafer stage base 29 are considered as a unit, and the vibration control for driving and controlling the part including the base 29 based on the barrel base 25 by the actuator units 31A to 31D. The compensation vibration system of FIG. 4 may be applied to the system control device.

Further, since exposure apparatus 100 is a scanning type exposure apparatus, reticle scanning stage 24A of reticle stage RST is stopped at the time of stepping of XY stage 14 of wafer stage WST. Is moved in a direction opposite to the XY stage 14 by a distance which is a reciprocal multiple of the projection magnification of the projection optical system PL. In this case, when the reticle scanning stage 24A is accelerated or decelerated, vibration occurs in a portion supported by the barrel base 25. Therefore, a command value of a reaction force in a direction opposite to the acceleration of the reticle scanning stage 24A may be fed forward to the feedback control system of the control device 50 to suppress the vibration generated when the reticle scanning stage 24A is accelerated or decelerated. .

Also, the position of the center of gravity of the portion of the exposure apparatus main body supported by the barrel base 25 may fluctuate due to the movement of the reticle stage RST during the scanning exposure, and the fluctuation may cause the barrel base 25 to tilt. There is. Therefore, in addition to the configuration shown in FIG. 4, a measured value corresponding to the tilt of the barrel base 25 is input to the control device 50, and the tilt of the barrel base 25 is corrected based on the measured value. May be calculated, and the correction value may be added to the command value to the actuator units 31A to 31D and the like.

FIG. 5 is a control block diagram showing a modified example of the vibration control system in the embodiment of FIGS. 5, components having the same functions as those in FIG. 4 are denoted by the same reference numerals, and descriptions of the functions will be omitted as appropriate. The control device 50 'of FIG. 5 differs from the control device 50 of FIG. 4 in that a disturbance observer non-interference controller 501 is inserted between the FF controller 92 and the fourth coordinate transformation unit 93. In the control device 50 shown in FIG. 4, the estimated disturbance estimated by the disturbance observer 201 is subtracted from the command value output from the speed controller 75 by the subtractor 104 after the high-frequency component is removed by the LPF 103 as described above. Is done. Therefore, it can be said that the performance of the disturbance observer 201 is determined by the LPF 103, and desired performance can be achieved in a frequency region lower than the frequency set by the LPF 103. In this case, if the command value compensated by the feedforward control system 200 includes an error in a frequency range lower than the frequency set by the LPF 103, this error component cannot be compensated by the disturbance observer 201, and the position control error It is possible that In order to solve such an effect caused by the interference relationship between the feedforward control and the disturbance observer, in the control device 50 ′ of FIG. 5, the disturbance observer non-interference controller 501 includes the FF controller 92 and the fourth coordinate conversion unit. By providing it between the first and second members 93, the interference relationship is prevented from occurring.

In this description, the separation of the frequency domain in which the desired performance can be achieved by the disturbance observer and the frequency domain of the error included in the command value compensated by the feedforward control system 200 is referred to as “feedforward control and disturbance”. The interference means is made non-interfering with the observer ", and the means for that is defined as a disturbance observer non-interference controller regardless of whether it is a single means or a combination of a plurality of elements. As a configuration of the disturbance observer non-interference controller 501, for example, an HPF complementary to the LPF 103 is used, and a set value (for example, a cutoff frequency) of the HPF becomes higher than the set value of the LPF 103 (for the filter). When the input is 1, the output of the HPF is the HPF, and the output of the LPF 103 is the LPF, the relationship of HPF = 1-LPF is satisfied. The disturbance observer non-interference controller 501 is configured to output a product of the output of the HPF and a mechanical transmission characteristic set between the actuators 31A to 31D and the acceleration sensor 18 that measures vibration. Is also good. Further, in FIG. 5, the disturbance observer non-interference controller 501 is provided between the FF controller 92 and the fourth coordinate conversion unit 93, but the present invention is not limited to this.

As described above in detail, in the present embodiment, among the command values output from the speed controller 75, the command values (Fz, Fθx, Fθy) in the Z-axis direction, the θx direction, and the θy direction are set on the base plate 21. Of the voice coil motor groups 311 and 12 by measuring the acceleration detected by the acceleration sensor group 18 disposed at the position, that is, the vibration component transmitted from the floor F, and performing feedforward control based on the measured value. The value is compensated. Therefore, in this embodiment, the vibration component generated on the floor surface F can be directly detected, and the vibration suppression control by the feedforward system based on the detected vibration component can be executed without delay. The effect of suppressing the disturbance vibration transmitted from the surface F can be improved.

The disturbance observer 201 obtains a difference between a command value input to the actuator groups 311 and 12 and a virtual command value estimated by the exposure apparatus main body model 101 based on the output of the displacement sensor group 19, thereby obtaining a disturbance component. And subtract the difference from the actual command value. Therefore, in the present embodiment, the command value to the voice coil motor groups 311 and 12 can be a command value in which the disturbance component is compensated, so that the vibration damping effect of the disturbance vibration can be improved.

Further, according to the exposure apparatus 100 of the above embodiment, at least a part of the exposure apparatus main body is configured by the vibration suppression device including the acceleration sensors 18A to 18D, the control device 50 (or 50 '), the actuator units 31A to 31D, and the like. (In the present embodiment, the portion based on the lens barrel base 25) is held, so that the vibration of the exposure apparatus main body is effectively suppressed, whereby it is possible to maintain the exposure accuracy with high accuracy. Become.

In the above embodiment, both the feedforward control system 200 and the disturbance observer 201 are provided as the compensation system of the vibration control system, but only one of them may be provided.

In the feedforward control system 200 in the above embodiment, the compensation by the feedforward control is performed on the command value output from the speed controller 75. However, the present invention is not limited to this. The compensation by the control system 200 may be performed on the speed command value output from the position controller 63, or may be performed on the position feedback or the position deviation input to the position controller 63.

In the above embodiment, the feedforward control system 200 and the disturbance observer 201 are introduced into the vibration control system by the drive control of the voice coil motor groups 311 and 12. A system or disturbance observer may be introduced. Further, the vibration control based on the vibration component of the floor vibration may not be the feedforward control but may be, for example, a feedback control. Further, the control device 50 (or 50 ') is a control device that performs vibration control with six degrees of freedom, but may be a control device with five degrees of freedom or less. Further, the control device 50 (or 50 ′) is a control device that performs both the position feedback control and the speed feedback control. However, only one of the controls may be performed. In addition to the control, acceleration feedback control may be performed.

The installation positions of the sensors such as the acceleration sensors 17A to 17C are not limited to the positions in the above-described embodiment, but may be any positions that can detect a vibration component generated in the exposure apparatus main body with a predetermined accuracy or more. Good.

In the above embodiment, the acceleration sensor is applied as a sensor for detecting floor vibration. However, the present invention is not limited to this, and another sensor such as a speed sensor or a displacement sensor may be used.

In the above-described embodiment, the feedforward control is performed based on only the vibration component (acceleration component) in the Z-axis direction detected by the acceleration sensor group 18. However, in addition to the vibration component in the Z-axis direction, the feedforward control is performed. , A component in the Y-axis direction or a rotation component, or the like, and the same feedforward control as in the present embodiment may be performed.

Also, in the above embodiment, the feedforward controller 92 is a second-order filter, but may be a controller represented by another transfer function such as a first-order filter. Note that the values of the control parameters such as Mn, Cs, and Kn of the feedforward controller 92 and the values of the parameters of the exposure apparatus main body model 101 of the disturbance observer 201 are determined in advance by a structural simulation or the like of the exposure apparatus 100. It may be a value and may be easily adjustable later by an operator.

In the above-described embodiment, the outputs of the acceleration sensor group 17 and the displacement sensor group 19 are used as the control amounts (observation amounts) of the exposure apparatus main body (projection optical system). May be. In this case, for example, a displacement component corresponding to the output of the displacement sensor group 19 may be obtained by second-order integration of the acceleration output from the acceleration sensor group 17, and the displacement component may be used for the position feedback control. A high-pass filter having a time constant equivalent to that of the HPF 71 may be provided between the displacement sensor group 19 and the first coordinate conversion unit 61.

The configuration of the actuator units 31A to 31D is not limited to the configuration as shown in FIG. 2, and various configurations can be considered for the positional relationship between the voice coil motors 311A to 311D and the pneumatic actuators 312A to 312D. In the present invention, it is desirable that these positional relationships be such that the control of the vibration of the high-frequency component by the voice coil motor and the control of the low-frequency component by the pneumatic actuator do not deteriorate the mutual control performance. . In the above embodiment, the voice coil motor or the pneumatic actuator is used as the actuator. However, the present invention is not limited to the type of the actuator. For example, a piezoelectric element or an EI core is used as the actuator. May be. In addition, a part of each actuator unit, for example, one of the four actuator units 31A to 31D may be replaced with a passive vibration isolating mechanism.

The control device 50 (or 50 ′) may be configured by hard wired, and a part thereof is a CPU (central processing unit), a ROM (read only memory), a RAM (random access memory). ), Etc., may be included. In general, it is more advantageous to use a microcomputer because maintenance such as a change in a control algorithm can be performed in a short time.

In the above-described embodiment, the portion including the projection optical system PL based on the lens barrel base 25 and the wafer stage base 29 in the exposure apparatus main body are controlled by the control device 50 and the like shown in FIG. Vibration of the portion (second stage system) is effectively suppressed.

Further, in the above embodiment, the wafer stage base 29 is of a type separated from the first column. However, the present invention is not limited to this. The present invention can also be applied to an exposure apparatus of a type not structurally separated from the surface plate 25. Further, the actuator units 39A to 39D may not be provided between the reticle stage base 33 and the support columns 27. That is, in the exposure apparatus of the above-described embodiment, only the actuator units 31A to 31D supporting the lens barrel base 25 or the actuator units 38A to 38D supporting the wafer stage base 29 may be provided.

Further, in the exposure apparatus of the above-described embodiment, only the vibration transmitted from the floor surface F, or in addition to this vibration, the lens barrel base due to the change in the center of gravity (unbalanced load) caused by the movement of the reticle stage RST or the wafer stage WST. 25, the inclination of the wafer stage base plate 29 is controlled or corrected by the actuator units 31A to 31D and 38A to 38D, and the reaction force (vibration) generated when the reticle stage RST or the wafer stage WST moves. May be suppressed by an anti-vibration mechanism provided separately from the actuator unit described above. The vibration damping mechanism may be, for example, a countermass method using the law of conservation of momentum, which cancels the reaction force by moving the countermass, or a frame provided separately from the supporting column 23 supporting the lens barrel base 25 ( A reaction frame system that allows the reaction force to escape to the floor or the like via a reaction bar) can be adopted.

Further, in the exposure apparatus of the above embodiment, the main body is installed on the base plate 21. However, for example, a caster frame may be used instead of the base plate 21, or the floor surface F may be provided without the base plate 21 or the like. May be provided with the above-described actuator section. Further, in the exposure apparatus of the above embodiment, at least a part of the illumination optical system constituting the illumination unit ILU may be installed on the lens barrel base 25 or the like. That is, the body structure and the like of the exposure apparatus (particularly, the main body) to which the present invention is applied are not limited to the above-described embodiment, and may have any structure.

Also, in the above-described embodiment, the case where the swing of the exposure apparatus main body in the direction of six degrees of freedom is suppressed using seven actuators has been described, but the present invention is not limited to this. For example, when it is sufficient to correct the inclination of the lens barrel base 25, at least three actuators in the Z direction may be used as the actuators. Further, the number of displacement sensors and acceleration sensors (vibration sensors) is not limited to six. In the above embodiment, the lens barrel base 25, the wafer stage base 29, and the reticle stage base 33 are supported by four support columns, respectively. Also, regarding the lighting unit ILU, an actuator unit similar to the actuator unit 31A or the like may be provided between the lighting unit ILU and the floor surface F, and vibration control may be performed using a control device similar to the control device 50 or the like. At this time, the entire lighting unit ILU may be supported by the actuator unit. For example, when a part of the lighting unit ILU is installed on the lens barrel base 25, only the remaining portion is supported by the actuator unit. Is also good.

In the above embodiment, the control device may analyze the vibration components measured by the acceleration sensors 18A to 18D and analyze the factors of the vibration components.

As described above, the factors of the vibration transmitted from the floor F include return vibration, earthquake, and vibration of other devices on the production line. In the control device, the natural frequency of the vibration component is obtained by vibration analysis processing such as FFT (Fast Fourier Transform), and the vibration is due to return vibration or vibration transmitted from another device. Can also be detected.

Also, when floor vibration with large amplitude occurs, such as in an earthquake with a large seismic intensity, it is necessary to immediately stop the process at that time to ensure the safety of workers and equipment and to prevent a decrease in yield. There is also. For this purpose, for example, in a control device that executes vibration control, when the amplitude of the vibration becomes equal to or greater than a predetermined value, exposure or the like may be immediately stopped. When performing such an operation, the amplitude of the vibration component detected by the acceleration sensors 18A to 18D or the like may be monitored as it is, but the amplitude of the estimated disturbance detected by the disturbance observer may be monitored. It may be. Further, when the occurrence of a vibration or an earthquake having a large amplitude is detected from the measurement result of the vibration, the wafer stage WST and the reticle stage RST which are levitated and supported on the wafer stage base 29 and the reticle stage base 33 are moved. It is preferable to fix the positional relationship so as not to collide with the lens barrel base 25 or the like.

Note that the analysis result of the above-described vibration analysis, the operation stop factor (vibration factor), and the like of the apparatus may be displayed on a display device (not shown) or may be stored as log data in a storage device (not shown). You may make it so. Further, even if the floor vibration is not the amplitude equal to or larger than the predetermined value, the floor vibration having a frequency close to the natural frequency of the exposure apparatus body or a frequency close to a multiple of the natural frequency of the exposure apparatus main body occurs. In this case as well, the vibration generated in the exposure apparatus main body is expected to increase, so that if the difference between the vibration frequency of the floor vibration and the natural frequency of the apparatus is within a predetermined value, the operation of the apparatus is stopped. It may be.

In the above embodiment, the case where the present invention is applied to a single wafer stage type step-and-scan type projection exposure apparatus has been described. However, the present invention is not limited to this. The present invention can be applied not only to a projection exposure apparatus of a system but also to other exposure apparatuses such as a projection exposure apparatus of a step-and-repeat type or an exposure apparatus of a proximity system. Further, similarly to reticle stage RST, wafer stage WST may be a coarse / fine movement stage. For example, using a voice coil motor or an EI core, the wafer table TB can be finely moved in the X-axis and Y-axis directions, and can be slightly rotated in the XY plane. Thereby, in wafer stage WST, XY stage 14 becomes a coarse movement stage, and wafer table TB becomes a fine movement stage capable of fine movement with respect to coarse movement stage 14 with six degrees of freedom.

In addition, the illumination unit and projection optical system composed of a plurality of lenses are incorporated into the main body of the exposure apparatus, and optical adjustment is performed. The exposure apparatus of the above-described embodiment can be manufactured by connecting and further performing overall adjustment (electrical adjustment, operation confirmation, and the like). It is desirable that the exposure apparatus be manufactured in a clean room in which the temperature, cleanliness, and the like are controlled.

In addition, the present invention is not limited to an exposure apparatus for manufacturing a semiconductor, but also an exposure apparatus for a liquid crystal for transferring a liquid crystal display element pattern onto a square glass plate, a display apparatus such as a plasma display and an organic EL, and a thin film magnetic head. It can also be applied to an exposure device for manufacturing an imaging device (such as a CCD), a micromachine, a DNA chip, and the like. Further, in the above embodiment, the case where the vibration damping device is applied to the exposure device has been described, but the present invention is not limited to this, and the transfer mask, that is, the reticle drawing device, the mask pattern position coordinate measuring device It is also applicable to precision measuring devices such as.

In addition to micro devices such as semiconductor elements, glass substrates or silicon wafers for manufacturing reticles or masks used in light exposure equipment, EUV exposure equipment, X-ray exposure equipment, electron beam exposure equipment, etc. The present invention can also be applied to an exposure apparatus that transfers a circuit pattern to a substrate. Here, in an exposure apparatus using DUV (far ultraviolet) light or VUV (vacuum ultraviolet) light, a transmission reticle is generally used, and as a reticle substrate, quartz glass, fluorine-doped quartz glass, fluorite, Magnesium fluoride, quartz, or the like is used. In a proximity type X-ray exposure apparatus, an electron beam exposure apparatus, or the like, a transmission type mask (stencil mask, membrane mask) is used, and a silicon substrate or the like is used as a mask substrate.

For a semiconductor device, a step of designing the function and performance of the device, a step of manufacturing a reticle based on this design step, a step of manufacturing a wafer from a silicon material, and transferring the reticle pattern to the wafer by the exposure apparatus of the above-described embodiment. This is manufactured through a step of performing, a step of assembling a device (including a dicing step, a bonding step, and a package step), an inspection step, and the like.

As described above, the vibration damping device according to the present invention is suitable for damping disturbance vibration such as floor vibration. The exposure apparatus of the present invention is suitable for transferring a pattern onto a photosensitive object.

FIG. 1 is a view schematically showing a structure of an exposure apparatus according to an embodiment of the present invention. It is a figure showing an example of the structure of an actuator part. FIG. 2 is a sectional view taken along line A-A ′ of FIG. 1. It is a control block diagram of a vibration control system. FIG. 9 is a block diagram illustrating a modification of the vibration control system of FIG. 4.

Explanation of reference numerals

31A to 31D: Actuator unit, 18A to 18D: Acceleration sensor (vibration measuring device), 50, 50 ': Control device (vibration control system), 91: Third coordinate conversion unit, 92: Feed forward (FF) controller ( 93: Fourth coordinate conversion unit, 100: exposure apparatus, 101: exposure apparatus body model, 104: subtractor, 200: feedforward control system, 201: disturbance observer, 311A to 311D: voice coil motor, 312A to 312D: air mount unit, 501: disturbance observer non-interference controller, PL: projection optical system, R: reticle, W: wafer.

Claims (14)

An actuator supporting the controlled object and capable of being driven vertically;
A vibration measuring device for measuring a vibration component transmitted from the floor side;
A vibration control system that calculates a command value to be given to the actuator based on a vibration component measured by the vibration measurement device, in order to suppress vibration generated in the control target. A vibration damping device that performs feedforward control based on a vibration component measured by a vibration measuring device. The vibration damping device according to claim 1, further comprising a member that supports the actuator and is provided with the vibration measuring device. The vibration measuring device,
The vibration damping device according to claim 2, wherein a portion of the member between the vibration measuring device and the actuator is provided within a range that can be regarded as a rigid body. The vibration control system,
The vibration suppression device according to any one of claims 1 to 3, wherein the command value is calculated by approximating a vibration system including the control target and the actuator to a secondary model. The vibration control system,
The vibration damping device according to claim 4, further comprising a coordinate conversion system that converts a vibration component measured by the vibration measuring device into a vibration component at a position where the actuator is installed. The vibration control system,
The vibration damping device according to claim 5, further comprising a secondary filter that inputs the vibration component converted by the coordinate conversion system, calculates and outputs a vibration component transmitted to the control target. The vibration control system,
The vibration damping device according to claim 6, further comprising a coordinate conversion system that converts a vibration component output from the secondary filter into a vibration component transmitted to a position of a center of gravity of the control target. A disturbance observer for estimating, as a disturbance component, a difference between a virtual command value estimated based on a control amount obtained from the control target by the model of the control target and the command value, further comprising a disturbance observer. The vibration damping device according to any one of Claims 7 to 7. The vibration damping device according to claim 8, wherein the vibration control system further includes a non-interference controller that makes the feed forward control and the disturbance observer non-interfering. An actuator supporting the controlled object and capable of being driven vertically;
Vibration control for creating a command value to the actuator based on a control amount obtained from the control object and controlling drive of the actuator by feedforward control based on the command value in order to suppress vibration generated in the control object System;
A disturbance observer for estimating, as a disturbance component, a deviation between a virtual command value estimated based on the control amount by the model of the control target and the command value;
A subtractor for subtracting a disturbance component estimated by the disturbance observer from the command value before the vibration control system drives and controls the actuator according to the command value;
A vibration control device, comprising: a non-interference controller for making the feed forward control and the disturbance observer non-interfering. An exposure apparatus for exposing a photosensitive object,
An exposure apparatus main body for performing the exposure;
An exposure apparatus comprising: the vibration suppression device according to any one of claims 1 to 10, wherein at least a part of the exposure apparatus body is a control target. The exposure apparatus according to claim 11, further comprising a passive vibration isolator that supports at least a part of the exposure apparatus body in a vertical direction. The exposure apparatus body includes:
A first stage system including a stage for holding a mask on which a predetermined pattern is formed;
A second stage system including a stage on which the photosensitive object is mounted;
A projection optical system for projecting exposure light onto the photosensitive object;
13. The exposure apparatus according to claim 11, wherein the vibration control device controls at least one of the second stage system and the projection optical system. The exposure apparatus body includes:
A first stage system including a stage that holds a mask on which a predetermined pattern is formed, a second stage system including a stage on which the photosensitive object is mounted, and a projection optical system that projects exposure light onto the photosensitive object; Has,
The vibration suppression device having the second stage system as a control target;
The exposure apparatus according to claim 11, further comprising: the vibration suppression device that controls the projection optical system.

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