JP2013225588A - Positioning device, exposing device and device manufacturing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve measurement accuracy by reducing deformation of a scale in a plate thickness direction in a positioning device provided with the scale and an encoder.SOLUTION: A positioning device comprises: a structure; a supporting unit that is provided on the structure and supports a scale; an encoder for measuring a position of a moving body with respect to the scale; a measuring instrument for measuring a position of the scale with respect to the structure associated with a plate thickness direction of the scale or a member supported by the structure; and a driving section for driving the moving body on the basis of output of the encoder. The supporting unit is configured so as to reduce vibration transmission from the structure in association with the plate thickness direction and is provided with a driving section for moving the scale in the plate thickness direction on the basis of output of the measuring instrument.

Description

  The present invention relates to a positioning device including an encoder and a scale. The present invention also relates to an exposure apparatus using such a positioning apparatus. Furthermore, the present invention relates to a device manufacturing method using such an exposure apparatus.

  A projection exposure apparatus that transfers a circuit pattern formed on an original to a substrate via a projection optical system has been used in the past. In recent years, an exposure apparatus that has higher resolution and is more economical is increasingly required. ing. One of the important performances of such an exposure apparatus is the overlay accuracy when a circuit pattern is transferred to a substrate. Normally, a plurality of circuit patterns are formed in multiple layers on a substrate, but an electronic circuit cannot be established unless the plurality of circuit patterns are aligned with a predetermined accuracy.

  Therefore, a technique for accurately aligning the substrate during exposure is important. As one of techniques for aligning substrates, a positioning device using a scale and an encoder has been proposed.

  Patent Document 1 describes a positioning device including a scale fixed to a lens barrel surface plate and an encoder fixed on a stage. In addition, this document describes that a scale is coupled to a lens barrel surface plate through a flexible element.

  In this positioning device, a plurality of flexure elements are arranged on a virtual circle centered on the central axis of the lens barrel. Since each flexible element has flexibility in the radial direction, the scale is prevented from being displaced even if the lens barrel surface plate is deformed by temperature fluctuation.

JP 2009-004737 A

  In the conventional exposure apparatus, the lens barrel surface plate is supported on the floor surface via a vibration isolator such as an air mount, and the vibration transmitted from the floor to the lens barrel surface plate is treated as negligible. However, in recent years, the accuracy required for the exposure apparatus has increased, and there is a concern about vibrations that cannot be completely removed by the air mount and are transmitted to the lens barrel surface plate.

  In particular, in a positioning device including a scale and an encoder, the scale is often mounted on a structure such as a lens barrel surface plate, and there is a concern that this vibration is transmitted to the scale. In particular, since the scale has a structure that is easily deformed in the thickness direction, the amount of deformation increases when vibration is transmitted in this direction. At this time, even when the frequency of vibration is sufficiently smaller than the natural frequency of the scale, there is a risk that deformation of the scale may increase due to the inertial force corresponding to the acceleration generated in the scale acting on the scale.

  In the positioning device of Patent Document 1, the deflection element is flexible in the radial direction, but the plate thickness direction of the scale is not taken into consideration, and the lens platen from the lens barrel surface plate to the scale in the plate thickness direction via the deflection element. The structure is easy to transmit vibration.

  The present invention has been made in view of the above points, and an object of the present invention is to improve measurement accuracy by reducing deformation of the scale in the plate thickness direction in a positioning device including a scale and an encoder.

  The present invention includes a structure, a support unit that supports the scale provided in the structure, an encoder that measures the position of the moving body with respect to the scale, and the structure or the structure related to the thickness direction of the scale. A positioning device comprising: a measuring instrument that measures a position of the scale relative to a member supported by the motor; and a drive unit that drives the moving body based on an output of the encoder, wherein the support unit is in the plate thickness direction And a drive unit configured to reduce vibration transmission from the structure and moving the scale in the plate thickness direction based on the output of the measuring instrument.

  According to the present invention, in a positioning device including a scale and an encoder, measurement accuracy can be improved by reducing deformation in the plate thickness direction of the scale.

Schematic of an immersion exposure apparatus to which the present invention is applied (A) is a bottom view of the scale in the present invention, (b) is a top view of the scale in the present invention. (A), (b) is the schematic of the support apparatus in this invention Example of scale deformation Scale top view in the present invention Schematic of the support device in the present invention Schematic of the support device in the present invention (A), (b) is a figure which shows the other example of the support apparatus in this invention, respectively. The figure which shows the vibration transmitted to the scale from the lens barrel surface plate via the support device for each frequency. The figure which shows the positive spring characteristic and negative spring characteristic of the support device

[Example 1]
An exposure apparatus according to the first embodiment will be described with reference to the drawings. In the drawings, constituent elements indicated by reference numerals with alphabets are part of constituent elements indicated by the same reference numerals without alphabets. Further, the optical axis direction of the exposure light of the exposure apparatus is defined as the Z direction, the directions orthogonal to the Z direction and the directions orthogonal to each other are defined as the X direction and the Y direction.

  FIG. 1 is a diagram illustrating an immersion exposure apparatus 80 according to the first embodiment. The pattern formed on the original (not shown) is imaged (exposed) on the substrate 30 via the projection optical system 10 (member supported by the structure). In the immersion exposure apparatus, exposure is performed in a state where the space between the projection optical system 10 and the substrate 30 is filled with the liquid 31.

  An original plate is a general term for members on which a pattern is formed, and is, for example, a mask or a reticle. The substrate is a general term for members to be exposed, and is, for example, a wafer or a glass substrate. The substrate 30 is mounted on a substrate stage (moving body), and the substrate stage is positioned by using a drive device and a position measurement system described later. The projection optical system 10 includes a plurality of optical elements and a lens barrel that surrounds the optical elements, and is supported by the lens barrel surface plate 9 (structure) via the vibration isolation device 22. The lens barrel surface plate is sometimes referred to as a support that supports the projection optical system. As the plurality of optical elements, for example, a lens, a mirror, or a combination of both can be applied. The lens barrel surface plate 9 is supported on the columnar member 44 fixed to the floor 43 via the vibration isolation device 20. The vibration isolation devices 20 and 22 are provided so as to suppress transmission of vibration or deformation. For example, a mount using air pressure, a mechanism for generating force using electricity or magnetism, an elastic member, or the like is applied. sell. Further, the vibration isolator may be a passive type or an active type.

  In the present embodiment, the substrate stage includes a coarse movement stage 41 that can move with a long stroke in the XY directions with respect to the base surface plate 42. Further, a fine movement stage that is movable in the X, Y, Z directions and rotational directions ωx, ωy, ωz directions (hereinafter referred to as six-axis directions) around an axis parallel to each direction in a short stroke with respect to the coarse movement stage 41. 40 is also provided. However, the substrate stage is not limited to this, and the substrate stage may be configured by one stage that serves both as the coarse movement stage and the fine movement stage. Further, the driving device 45 (driving unit) is provided for driving the substrate stage (in the figure, for coarse movement stage and for fine movement stage, respectively), for example, a linear motor is preferably used. The driving device 45 is controlled by the control unit 100. The control unit 100 can be configured from a CPU or MPU, ROM, RAM, recording unit, driver, and the like, and the configuration is not particularly limited.

  The position of the substrate stage in the six axis directions is measured by a position measurement system.

  The position measurement system includes an encoder 7 mounted on a substrate stage and a scale 1 supported by a lens barrel base plate 9. As the scale 1, various scales in a known position measurement system can be applied. In this embodiment, the scale 1 includes a plate-like diffraction grating 2. The diffraction grating 2 may be directly formed on a plate-like member, or the member on which the diffraction grating is formed may be attached to the plate-like member. Using the encoder 7 and the scale 1, the relative position of the substrate stage with respect to the scale 1 can be measured. Then, the driving device 45 is controlled to drive the substrate stage based on the output of the encoder 7. For example, feedback control using known PID compensation can be applied.

  Further, the position measurement system includes a support device (support unit) 3 that supports the scale 1 in a non-contact manner with respect to the lens barrel base plate 9 and a drive that drives the scale 1 with respect to the lens barrel base plate 9 in six axial directions. A device 4 (drive unit) is provided. Further, a position sensor 5 (measuring instrument) that measures the relative position of the scale 1 in the six-axis direction with respect to the projection optical system 10 is provided. In the figure, a part of the position sensor 5 and the encoder 7 and the measurement optical axis 6 and the measurement optical axis 8 are shown as an example.

  The support device 3 includes a rotation direction (θx,) having a plate thickness direction (Z) of the scale 1, two directions (X, Y) parallel to the plate surface of the scale 1 and orthogonal to each other, and an axis parallel to each direction as a rotation axis. (θy, θz), vibration transmission from the surface plate 9 to the scale 1 can be reduced.

  FIG. 2A is a bottom view of the scale 1 (viewed from the −Z direction). In this embodiment, the scale 1 includes four plates 2a, 2b, 2c, and 2d (indicated by reference numeral 2 in FIG. 1) on which diffraction gratings are formed, and a plate-like member to which these plates are attached, including. The light from the encoder 7 is applied to the diffraction grating, and the position of the substrate stage corresponding to the diffracted light is measured by a light receiving element (not shown).

  FIG. 2B is a top view of the scale 1 (viewed from the + Z direction). On the scale 1, position sensors 5a to 5d (indicated by reference numeral 5 in FIG. 1) are mounted. For example, a capacitance sensor, an interferometer, or a linear encoder can be used as the position sensors 5a to 5d. Each of the position sensors 5a and 5b can measure the position of the scale 1 in the X direction and the Z direction with respect to the projection optical system 10, and each of the position sensors 5c and 5d can measure the Y direction of the scale 1 with respect to the projection optical system 10 and The position in the Z direction can be measured. The rotation direction (θx, θy, θz directions) can be obtained from the difference between the two outputs of the position sensor. Further, an average value of outputs of redundant position sensors may be used as a measurement value. The number and the arrangement of the position sensors are not limited to this, and it is sufficient that the position of the scale 1 with respect to the projection optical system 10 in the six-axis directions can be measured. Note that the position measurement of the scale 1 is described in Japanese Patent Laid-Open No. 2009-27141.

  Further, the scale 1 and the lens barrel surface plate 9 are provided with drive devices 4a to 4h (indicated by reference numeral 4 in FIG. 1) and support devices 3a to 3d (indicated by reference numeral 3 in FIG. 1). As the driving devices 4a to 4h, non-contact type devices having a vibration isolation effect are suitably applied. Examples of such a driving device include a Lorentz type linear motor and an electromagnet actuator. The driving devices 4a to 4h are controlled by the control unit 100. Control of the driving devices 4a to 4h will be described later. Furthermore, you may provide the cooling part which cools a drive device.

  Fig.3 (a) is a figure which shows the detail of the support apparatus 3a, FIG.3 (b) is the perspective view. Since the configuration of the support devices 3b, 3c, and 3d is the same as that of the support device 3a, description thereof is omitted.

  The support device 3 a includes a pair of magnets 32 fixed to the lens barrel surface plate 9 via a support member 31 and a magnet 34 fixed to the scale 1 via a support member 33. The pair of magnets 32 are disposed so as to face each other with a gap therebetween, and the magnet 34 is disposed between the pair of magnets 32 in a non-contact manner. That is, the magnets are arranged on the lens barrel base plate 9 side (structure side) and the scale 1 side. Each magnet is a permanent magnet and is magnetized in the magnet thickness direction, that is, in the X direction, and the magnet 32 and the magnet 34 are arranged so that the same poles face each other.

  The support device 3 a preferably includes yokes 35 and 36 for strengthening the magnetic flux of the magnetic circuit formed by the magnet 32. As a material of the yoke, for example, a soft magnetic material such as iron is used.

  Due to the magnetic repulsion between the pair of magnets 32 and 34, a levitation force in the + Z direction acts on the magnet 34. The repulsive force in the X direction that acts between one magnet of the magnet 32 and the magnet 34 is offset by the repulsive force that acts between the other magnet and the magnet 34.

  The number and arrangement of the support device and the drive device are not limited to the illustrated form. In this embodiment, linear motors (4e, 4f) that can be driven in the X direction are arranged symmetrically with respect to the Y axis passing through the center of gravity of the scale 1. Further, linear motors (4g, 4h) that can be driven in the Y direction are arranged symmetrically with respect to the X axis passing through the center of gravity of the scale 1. Linear motors (4 a to 4 d) that can be driven in the Z direction are arranged at the four corners of the scale 1. In order to apply a symmetrical force to the scale 1, it is preferable that both the support device and the drive device have symmetry with respect to the scale 1. By providing symmetry, deformation can be suppressed, or deformation can be predicted and corrected easily.

  Hereinafter, the characteristics of the support device of the present embodiment will be described. The support device of the present embodiment has the following two features.

  The first feature is that the scale 1 is supported in a non-contact manner with respect to the lens barrel surface plate. Since the support device described in Japanese Patent Application Laid-Open No. 2009-004737 is supported through the deflection element, the temperature fluctuation of the lens barrel surface plate 9 is transmitted to the scale 1 through the deflection element. When the measurement error of the position measurement system is set to 0.1 nm or less, it is necessary to suppress the temperature change of the scale 1 to the order of 1 to 10 mK. Since the lens barrel surface plate used in the exposure apparatus has a very large surface area compared to the scale, a temperature change of the order of 100 mK occurs due to a temperature fluctuation in the surrounding environment. In addition, since the lens barrel surface plate itself is large, it is difficult to precisely adjust the temperature.

  In this embodiment, since the scale 1 is supported in a non-contact manner with respect to the lens barrel base plate 9, the temperature fluctuation of the lens barrel base plate 9 is not easily transmitted to the scale 1, and the deformation due to the temperature fluctuation of the scale 1 is reduced. be able to.

  The second feature is that the absolute value of the spring constant in the plate thickness direction (Z direction) of the scale is very small. Preferably, the absolute value of the spring constant in the 6-axis direction is very small. In other words, the scale 1 is supported in a vibrationally insulated state.

  Since the scale 1 is plate-shaped, deformation is most likely to occur due to inertial force acting in the thickness direction of the scale 1 in terms of material mechanics. FIG. 4 shows the shape of the scale 1 when vibration is transmitted from the lens barrel surface plate in the support device that rigidly supports (fixes) the scale 1 in the thickness direction. Forces F1 to F4 are applied to the scale 1 at the support portions 108a to 108d, and the acceleration is generated in the entire scale 1 by the force, and the inertial force F5 is applied. As a result, deformation as shown in FIG. 4 occurs.

  The inertial force F5 generated in the scale 1 is represented by [scale mass] × [vibration amplitude] × [angular frequency of vibration] ^ 2. That is, while the inertial force is proportional to the vibration amplitude, the inertial force is also proportional to the square of the vibration frequency [rad / s] or the square of the vibration frequency [Hz] that is proportional to the angular frequency. Therefore, reducing high-frequency vibration transmitted to the scale 1 is effective for reducing the deformation amount of the scale 1.

  In recent exposure apparatuses, since the accuracy of about 0.1 nm is required for measuring the position of the substrate stage, the deformation amount of the scale 1 needs to be 0.1 nm or less. According to the analysis result, when the thickness of the scale 1 is several tens of millimeters, the thickness of the support device 3 is controlled in order to suppress the amount of deformation of the scale 1 due to vibration in the thickness direction to 0.1 nm or less. The natural frequency in the direction may be 10 Hz or less. Here, when the scale 1 is rigidly supported in the thickness direction, the natural frequency is 100 Hz or more, which is not preferable. In this embodiment, the natural frequency is set to 10 Hz or less by supporting the scale 1 with the support device 3 using the repulsive force of the magnet.

  As a result, it is possible to significantly reduce deformation of the scale 1 due to vibration transmission from the lens barrel surface plate to the scale 1.

  Subsequently, positioning control of the scale 1 using the driving device 4 in the present embodiment will be described. The support device 3 of the present embodiment has a small absolute value of the spring constant and is difficult to generate acceleration in the scale 1, but on the other hand, the position stability of the scale 1 is deteriorated. For example, the scale 1 may be displaced due to the influence of the wind pressure accompanying the movement of the substrate stage. Therefore, in the driving device 4 of this embodiment, both the position stability of the scale 1 and the suppression of the acceleration generated in the scale 1 are made compatible.

  In order to describe the positioning control of the present embodiment in detail, first, the relationship between the support device 3 and the positioning control will be described.

  In this embodiment, the position of the scale 1 relative to the projection optical system 10 in the 6-axis direction is measured by the position sensor 5, and the drive device 4 is moved in the 6-axis direction so that the relative position has a predetermined relationship based on the measurement result. To control. Specifically, feedback control using PID compensation is applied.

  However, there is a concern that the positioning control of the scale 1 amplifies vibration when the positioning control of the scale 1 is performed and the scale 1 is caused to follow the projection optical system 10.

  FIG. 9 is a diagram showing a transmission rate of vibration transmitted from the lens barrel surface plate 9 to the scale 1. The horizontal axis indicates the frequency, the vertical axis indicates the amplitude of the scale 1 due to vibration, and both axes are expressed logarithmically. In the figure, the natural frequency of the support device 3 is fc.

  The natural frequency of the support device 3 is a frequency [Hz] determined by the spring constant of the support device 3 and the mass of the scale 1 and is set to 2 Hz in this embodiment.

  In a region where the vibration frequency of the lens barrel base plate 9 is sufficiently lower than the natural frequency fc (for example, 0.5 Hz or less), the lens barrel base plate 9 and the scale 1 vibrate as if they were an integral structure. The vibrations of are substantially the same in both amplitude and phase. When the projection optical system 10 is supported by a spring element having a natural frequency (for example, 10 Hz) sufficiently higher than the support device 3 with respect to the lens barrel base plate 9, the projection optical system 10 and the lens barrel base plate 9 vibrates like an integral structure. That is, the projection optical system 10, the lens barrel surface plate 9, and the scale 1 all vibrate as an integrated structure.

  In the region where the vibration frequency of the lens barrel surface plate 9 is close to the natural frequency fc (for example, 0.5 Hz to 3 Hz), the vibration of the lens barrel surface plate 9 is amplified by an amount corresponding to the attenuation ratio of the support device 3 and scaled. It is transmitted to 1.

  In a region where the vibration frequency of the lens barrel surface plate 9 is sufficiently higher than the natural frequency fc (for example, 3 Hz or more), the vibration of the lens barrel surface plate 9 is difficult to be transmitted to the scale 1.

  As described above, since the vibration is easily amplified (that is, easily resonated) in the region near the natural frequency fc, it is necessary to set the servo control frequency sufficiently lower than the natural frequency fc in the positioning control of the scale 1. is there. Therefore, in this embodiment, as an example, the natural frequency fc of the support device 3 is set to about 2 Hz in all six axis directions, and the servo control frequency is set to ½ or less of the natural frequency fc to avoid resonance. ing. Preferably, the servo control frequency is set to ¼ or less (for example, 0.5 Hz) of the natural frequency fc.

  The “servo control frequency” (also referred to as a servo control band) is defined by the zero cross frequency in the open characteristic, and serves as an index indicating the boundary of whether or not the follow-up control functions sufficiently. That is, when the servo control frequency is set to 0.5 Hz, the control does not function for the movement of the frequency of 0.5 Hz or more, but the control functions for the movement of the lens tube of the frequency of 0.5 Hz or less, and the scale 1 Can be prevented from drifting in the low frequency band.

  By setting the servo control frequency lower than the natural frequency 2 Hz of the support device 3 (0.5 Hz), only the frequency region where the projection optical system 10, the lens barrel surface plate 9 and the scale 1 vibrate together is positioned. Control is functioning. For this reason, even if positioning control is not performed, the scale 1 originally follows the movement of the projection optical system 10, so that positioning control is meaningless. In the ideal case where the force acting on the scale 1 is only due to the support device 3, such positioning control is meaningless. However, in reality, force is applied to the scale 1 due to the force transmitted from the cables of the sensors mounted on the scale 1 and the uneven pressure change around the scale 1 due to the movement of the stage 40 below the scale 1. With this force, the positional relationship between the scale 1 and the projection optical system 10 gradually shifts. That is, a drift phenomenon occurs in which the scale 1 is displaced at a very low frequency (for example, 0.1 Hz or less). For example, when the gap between the position sensor 5 and the projection optical system 10 is set to about 0.3 to 0.5 mm, the gap variation needs to be suppressed to 0.1 mm or less in order to keep the measurement accuracy of the position sensor 5 high. Yes, the above-described control is effective to reduce the gap fluctuation.

  As described above, the support device of the present embodiment is configured to reduce vibration transmission from the lens barrel surface plate 9 in the thickness direction of the scale 1. As a preferred example, when the natural frequency of the support device 3 in the plate thickness direction of the scale 1 is fc, the servo control frequency for positioning control of the scale 1 is ½ or less of the natural frequency fc. It is set. Thereby, the inertial force generated in the scale 1 by the positioning control of the scale 1 can be suppressed, and the deformation of the scale 1 in the plate thickness direction due to vibration can be greatly reduced.

  In this embodiment, position measurement in the 6-axis direction and driving in the 6-axis direction are described as preferred examples, but position measurement only in the plate thickness direction of the scale and drive only in the plate thickness direction may be used. Further, in this embodiment, the position sensor 5 measures the position of the scale 1 with respect to the projection optical system 10 (member supported by the structure). The position of the scale 1 with respect to) may be measured.

  In this embodiment, the scale 1 is supported by the lens barrel base plate 9, but may be supported by a structure other than the lens barrel base plate 9. Also in that case, the structure is supported via the vibration isolation device.

  The configuration of the exposure apparatus 80 in the present embodiment is an example, and the configuration may be different without departing from the spirit of the invention. For example, it is not limited to any of the step-and-scan method, the step-and-repeat method, and other methods, and is not limited to the wavelength of a predetermined light source, and is not limited to either the liquid immersion method or the non-liquid immersion method. Further, the present invention is not limited to an exposure apparatus, and can be applied to, for example, a charged particle beam drawing apparatus that does not use an original plate, an imprint apparatus, a digital microscope, and a positioning apparatus used in a machine tool.

  When the above-described position measurement system is applied to a charged particle beam drawing apparatus, an electron optical system for deflecting or shaping a charged particle beam can be applied instead of the projection optical system.

  When the above-described position measurement system is applied to the imprint apparatus, a pattern on which a pattern is formed or a support that supports the mold can be applied instead of the projection optical system.

  When the above-described position measurement system is applied to a digital microscope, an optical system constituting the microscope can be applied instead of the projection optical system.

[Example 2]
A position measurement system according to the second embodiment will be described. An acceleration sensor 60 (acceleration measuring means) is added on the scale 1 with respect to the configuration of the first embodiment, and the output of the acceleration sensor 60 is used for controlling the driving device 4. In the following description, portions different from those in the first embodiment will be described, and description of portions having functions similar to those in the first embodiment will be omitted.

  FIG. 5 is a top view of the scale 1 of the second embodiment. In the figure, portions having the same functions as those in the first embodiment are denoted by the same reference numerals.

  In the scale 1, acceleration sensors 60a to 60d that detect acceleration in the thickness direction of the scale 1 are arranged. The control unit controls the driving devices 4a to 4h so as to cancel the acceleration generated in the scale 1 based on the acceleration detected by the acceleration sensors 60a to 60d. That is, the drive device is controlled so that the outputs of the acceleration sensors 60a to 60d become zero.

  In this embodiment, the acceleration sensor detects the acceleration in the plate thickness direction of the scale 1, but may detect the acceleration in other directions (for example, the 6-axis direction), and in that case, the plate generated in the scale 1 The acceleration other than the thickness direction can be canceled out.

  The above-described acceleration control in the second embodiment is performed together with the position control for preventing the drift in the first embodiment. Since the servo control frequency of the acceleration control is not limited as in the position control, the deformation of the scale 1 can be further reduced by setting it as high as possible.

  The driving devices 4a to 4d are preferably arranged in the vicinity of the supporting devices 3a to 3d. Furthermore, the acceleration sensors 60a to 60d are preferably arranged in the vicinity of the supporting devices 3a to 3d and the driving devices 4a to 4d that drive in the plate thickness direction. With such an arrangement, when the force transmitted from the support devices 3a to 3d to the scale 1 is canceled by the force generated by the drive devices 4a to 4d, local deformation of the scale 1 caused by the difference in the point of action of each force is prevented. Can be reduced.

  When the natural frequency fc of the support device 3 is 2 Hz, vibrations of about 3 Hz (2 Hz × √2) or more are attenuated among the vibrations of the lens barrel surface plate 9 and transmitted to the scale 1. According to the present embodiment, vibration with a frequency transmitted to the scale 1 of 3 Hz or less can also be reduced. Therefore, the deformation of the scale 1 can be further reduced as compared with the configuration of the first embodiment.

[Example 3]
A position measurement system according to the third embodiment will be described. The support device of the first embodiment sets the servo control frequency to ½ or less of the natural frequency fc, whereas in this embodiment, the servo control frequency is √2 times or more and 10 times or less of the natural frequency fc. Is set. In the following description, portions different from those in the first embodiment will be described, and description of portions having functions similar to those in the first embodiment will be omitted.

  If the servo control frequency is set to a frequency higher than the natural frequency fc, the vibration is transmitted in the frequency region where the support device 3 is difficult to transmit the vibration (region of √2 times fc or more in FIG. 9). However, for example, by setting the servo control frequency to 5 to 10 Hz that avoids the vicinity of the natural frequency fc (for example, 1 to 3 Hz), vibration of the scale 1 due to resonance is reduced, and deformation of the scale 1 is suppressed. It becomes possible.

  For example, when the servo control frequency is set to 10 Hz, vibration of the lens barrel 19 up to 10 Hz is transmitted. However, since the resonance of the scale 1 of about 1 to 3 Hz can be suppressed, it occurs in the scale 1. It is possible to suppress the inertial force.

  The servo control frequency may be at least √2 times the natural frequency fc of the support device 3, more preferably at least twice the natural frequency fc. This is because if the servo control frequency is too close to the natural frequency fc, the control becomes unstable. In addition, when the damping ratio of the support device 3 is small, the vibration amplification ratio near the natural frequency fc is large, so that the vibration suppression effect when the present embodiment is implemented becomes more remarkable. If the servo control frequency of the scale 1 is 10 times or less the natural frequency fc of the support device 3, a sufficient vibration suppressing effect can be obtained.

[Example 4]
A position measurement system according to the fourth embodiment will be described. The configuration of the support device is different from the configuration of the first embodiment. Specifically, the support device of Example 1 is a non-contact type, whereas the support device of this example is a contact type. Similar to the first embodiment, the support device is configured such that the support rigidity (spring constant) of the scale 1 in the plate thickness direction is small. In the following description, portions different from those in the first embodiment will be described, and description of portions having functions similar to those in the first embodiment will be omitted.

The support device of FIG. 6 supports the scale 1 by a coil spring 71. One end of the coil spring 71 is attached to the scale 1 side, and the other end is attached to the barrel base plate 9 side. Such a coil spring 71 has not only low support rigidity in the plate thickness direction (Z direction) of the scale 1 (that is, soft support), but also low rigidity in the XY directions. When the support rigidity of the coil spring is lowered, adjustment is necessary so that the extension amount of the coil spring does not become too large due to the mass of the scale 1 in the initial state.

As shown in FIG. 7, the scale 1 may be supported by a leaf spring 73 instead of the coil spring 71 of FIG. 6.

[Example 5]
A position measurement system according to the fifth embodiment will be described. The support device of Example 1 is non-contact type, but the support device of Example 5 is different in that it is contact type. Since the first feature in the first embodiment is not provided, the temperature fluctuation of the scale 1 is likely to occur as compared with the configuration of the first embodiment. However, by providing the second feature, the deformation of the scale 1 can be reduced. it can. In the following description, portions different from those in the first embodiment will be described, and description of portions having functions similar to those in the first embodiment will be omitted.

  FIG. 8A shows a support device in the fifth embodiment. Although one supporting device is shown in the figure, the position measurement system includes a plurality of supporting devices as in the first embodiment, and other supporting devices not shown in the figure have the same configuration.

  The support device includes a magnet 72 a fixed to the lens barrel base plate 9, a magnet 72 b fixed to the scale 1 so as to face the magnet 72 a, and a coil spring 71 that connects the lens barrel base plate 9 and the scale 1. With. The magnets 72a and 72b are permanent magnets. The coil spring 71 may have other configurations as long as it acts as a spring element.

  The scale 1 is supported by a supporting force determined by a magnetic repulsive force acting between the magnet 72 a and the magnet 72 b and a restoring force of the coil spring 71. The magnets 72a and 72b generate a non-linear spring force with respect to the displacement of the scale 1, and the coil spring 71 is configured to generate a linear spring force.

  Further, by adjusting the spring force and the support position of the scale 1, a support force for supporting the scale 1 can be obtained, and the extension amount of the coil spring 71 with respect to the displacement in the vicinity of the balanced position can be suppressed. This reduces the distance between the scale 1 and the lens barrel surface plate 9 and saves space. Furthermore, the absolute value of the spring constant at the balanced position can be reduced by adjustment.

  FIG. 8B is a modification of FIG. The support device illustrated in FIG. 8B uses an air spring (Bellofram) 73 instead of the coil spring 71. Further, magnets 72c to 72f are used in place of the magnets 72a and 72b. The magnets 72c to 72f are different from the support device of FIG. 8A in that magnetic attraction is used.

[Example 6]
This embodiment is different from the first embodiment in the characteristics of the support device. FIG. 10 shows the position of the scale 1 in the plate thickness direction (Z direction) when the scale 1 is supported using the support device 3a shown in FIGS. 3A and 3B (the same applies to 3b to 3d); It is a figure which shows the relationship with the force of the plate | board thickness direction which the support apparatus 3a gives to the scale 1. FIG. F _G is the gravitational force exerted on the scale 1 and the like, which is supported by the supporting device 3a.

  The support device 3a has negative spring characteristics and positive spring characteristics according to the position of the scale 1 in the plate thickness direction. Here, the “negative spring characteristic” is a characteristic that generates a force in a direction away from the balance position when it deviates from the balance position when the object is supported. In contrast, the “positive spring characteristic” is a characteristic that generates a force to return to the balance position when it deviates from the balance position when the object is supported.

  In the first embodiment, the positional relationship between the magnet 32 and the magnet 34 is adjusted so that the support device has a positive spring characteristic, whereas in the present embodiment, the support device has a negative spring characteristic. The positional relationship between the magnet 32 and the magnet 34 is adjusted. In other words, in the first embodiment, the scale 1 is supported at a position where the spring constant of the support device becomes positive, whereas in this embodiment, the scale 1 is moved at a position where the spring constant of the support device becomes negative. I support it.

  The support device described in Japanese Patent Application Laid-Open No. 2009-004737 uses a flexure element, and resonance due to the mass of the flexure element (spring element) itself and the spring constant becomes a problem. In the conventional example, even if the spring constant of the flexure element is made as small as possible, a plurality of natural frequencies (resonance frequencies) exist from several tens of Hz due to the mass of the flexure element itself, and vibration in the thickness direction transmitted from the lens barrel base plate 9 Will be amplified. Such vibration causes deformation of the scale 1.

  Also in the first embodiment, as described with reference to FIG. 9, in the region where the vibration frequency of the lens barrel surface plate 9 is in the vicinity of the natural frequency fc (for example, 0.5 Hz to 3 Hz), the vibration of the lens barrel surface plate 9 Then, the signal is amplified by an amount corresponding to the damping ratio of the support device 3 and transmitted to the scale 1. Such amplification occurs in the positive spring characteristic, and since the support device has the negative spring characteristic in this embodiment, there is no problem of resonance due to amplification. Therefore, the deformation of the scale 1 can be reduced as compared with the first embodiment.

  A support device having a negative spring characteristic does not have a general natural frequency because the spring constant is defined as negative. Accordingly, the following frequency fc is defined as the frequency corresponding to the natural frequency.

  (Expression 1) is a modification of an expression representing a general natural frequency, and the spring constant k in the expression representing the natural frequency is an absolute value. m is the mass of the scale 1 or the total mass of the objects mounted on the scale 1 and the scale 1. Since the resonance phenomenon does not occur in the case of the negative spring characteristic, the frequency fc does not mean the frequency that causes resonance. However, (Equation 1) can be a guideline for knowing how much vibration is difficult to be transmitted due to the effect of the inertial force acting on the supported object or how much spring force acts on the supported object.

  Here, even if the spring constant is negative, the characteristic that the vibration of the lens barrel surface plate 9 is difficult to be transmitted to the scale 1 due to its small absolute amount is the same as when the spring constant is positive.

  Similarly, in Examples 2 to 4, the spring constant may be negative instead of positive.

(Device manufacturing method)
Next, a method for manufacturing a device (semiconductor device, liquid crystal display device, etc.) according to an embodiment of the present invention will be described. A semiconductor device is manufactured through a pre-process for producing an integrated circuit on a wafer and a post-process for completing an integrated circuit chip on the wafer produced in the pre-process as a product. The pre-process includes a step of exposing a wafer coated with a photosensitive agent using the above-described exposure apparatus, and a step of developing the wafer. The post-process includes an assembly process (dicing and bonding) and a packaging process (encapsulation). A liquid crystal display device is manufactured through a process of forming a transparent electrode. The step of forming the transparent electrode includes a step of applying a photosensitive agent to a glass substrate on which a transparent conductive film is deposited, a step of exposing the glass substrate on which the photosensitive agent is applied using the above-described exposure apparatus, and a glass substrate. The process of developing is included. According to the device manufacturing method of the present embodiment, it is possible to manufacture a higher quality device than before.

  As mentioned above, although preferable embodiment of this invention was described, this invention is not limited to these embodiment, A various deformation | transformation and change are possible within the range of the summary.

1 Scale 2, 2a, 2b, 2c, 2d Diffraction grating 3, 3a, 3b, 3c, 3d Support device 4, 4a, 4b, 4c, 4d, 4e, 4f, 4g, 4h Drive device 5, 5a, 5b, 5c 5d Position sensor 7 Encoder 9 Lens barrel plate 10 Projection optical system 30 Substrate 32, 34 Permanent magnet 40 Fine movement stage 41 Coarse movement stage 45 Drive device 60, 60a, 60b, 60c, 60d Acceleration sensor 80 Immersion exposure apparatus

Claims (9)

A structure,
A support unit for supporting the scale provided in the structure;
An encoder for measuring the position of the moving body with respect to the scale;
A measuring instrument for measuring the position of the scale relative to the structure or a member supported by the structure in the thickness direction of the scale;
A driving unit that drives the movable body based on the output of the encoder, and a positioning device comprising:
The support unit is configured to reduce vibration transmission from the structure in the plate thickness direction;
A positioning device comprising: a drive unit that moves the scale in the plate thickness direction based on an output of the measuring instrument.   The servo control frequency of the drive unit for moving the scale is ½ or less, or 2 to 10 times the natural frequency of the support unit in the plate thickness direction. The positioning device described in 1.   The positioning device according to claim 1, wherein the support unit has a natural frequency of 10 Hz or less in the plate thickness direction.   The positioning device according to claim 1, wherein the support unit supports the scale in a non-contact manner.   The support unit transmits vibrations from the structure in the plate thickness direction, two directions parallel to the plate surface of the scale and orthogonal to each other, and a rotation direction having an axis parallel to each direction as a rotation axis. The positioning device according to any one of claims 1 to 4, wherein the positioning device is configured to reduce the amount of the positioning device. The support unit has a pair of first permanent magnets attached to one of the scale and the structure, and a second permanent magnet attached to the other,
At least one of the first and second permanent magnets is magnetized in a direction orthogonal to the plate thickness direction, and a force acting between the first permanent magnet and the second permanent magnet is used. The positioning device according to claim 1, wherein the scale is supported. An acceleration sensor for detecting the acceleration of the scale;
The positioning device according to claim 1, wherein the driving unit that moves the scale moves the scale based on an output of the acceleration sensor.   An exposure apparatus for positioning a substrate using the positioning apparatus according to claim 1.   A device manufacturing method comprising: exposing a substrate using the exposure apparatus according to claim 8; and developing the exposed substrate.

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