JP2016194599A - Vibration isolation device and control method thereof, and exposure method and device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve vibration isolation performance without increasing the number of measuring devices for measuring the absolute position of a vibration isolation object.SOLUTION: A vibration isolation device 20 for supporting a base member 24 on a floor FL comprises: an elastic member 48 for supporting the base member 24 with respect to the floor FL; an air damper 40 for suppressing the vibrations of the base member 24 with respect to the floor FL; a position sensor 52 for detecting a position signal corresponding to the position of the base member 24 relative to the floor FL; a motor unit 50 for adjusting the position of the base member 24 relative to the floor FL; and a control system 36 for driving the motor unit 50 in accordance with the position signal detected by the position sensor 52, the control system 36 including a characteristic change unit which electrically converts the stiffness of the elastic member 48 into a target value.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a vibration isolator for suppressing vibration when supporting a structure, a control method thereof, an exposure technique using the vibration isolator, and a device manufacturing technique using the exposure technique.

  For example, in a lithography process, which is one of the manufacturing processes of an electronic device (microdevice) such as a semiconductor device or a liquid crystal display element, a wafer (or glass plate) on which a pattern formed on a reticle (mask) is coated with a photoresist. For example, a batch exposure type (stationary exposure type) exposure apparatus such as a stepper or a scanning exposure type exposure apparatus such as a scanning stepper is used.

  Conventionally, in an exposure apparatus, in order to eliminate the influence of vibration and improve exposure accuracy such as reticle stage and wafer stage positioning accuracy and overlay accuracy, the base member (surface plate) and floor ( An anti-vibration table is arranged between the installation surface). As a conventional anti-vibration table, a passive type anti-vibration table that supports an object to be anti-vibrated using an air damper or the like that is controlled so that the internal pressure becomes almost constant by an open loop method is known. Recently, using a detection signal of a sensor that measures the relative position of the vibration-proof object with respect to the installation surface and a sensor that measures the acceleration of the vibration-proof object, the drive mechanism is driven in a closed loop manner to detect the vibration-proof object. An active vibration isolator that suppresses vibration has also been proposed (see, for example, Patent Document 1).

JP 2009-2509 A

  In the conventional active vibration isolator, since a plurality of sensors for measuring the relative position and acceleration are provided, the mechanism becomes complicated and the control circuit for the drive mechanism becomes complicated, resulting in an increase in manufacturing cost. It was.

  According to the first aspect of the present invention, in the vibration isolator that supports the structure on the installation surface, the elastic mechanism that supports the structure with respect to the installation surface, and the vibration of the structure with respect to the installation surface A damper mechanism that suppresses vibration, a detection unit that detects a position signal corresponding to the relative position of the structure with respect to the installation surface, an adjustment unit that adjusts the relative position of the structure with respect to the installation surface, and the detection unit A control unit that generates a drive signal for driving the adjusting unit according to the detected position signal, and the control unit includes a mass of the structure, a rigidity of the elastic mechanism, and a damper mechanism. A first signal generated using a first transfer function including at least one of the viscosity proportional coefficients of the damper and a position signal thereof; the mass of the structure; the rigidity of the elastic mechanism; and the damper mechanism Having damper Generating a drive signal using a second signal that includes at least one of the sex proportionality coefficients and that is generated using a second transfer function different from the first transfer function and the position signal A vibration isolator is provided.

According to the second aspect, there is provided an exposure apparatus that exposes a pattern onto an object to be exposed, the frame, a stage that supports the object to be exposed and is relatively movable with respect to the frame, An exposure apparatus for controlling the relative position of the frame with respect to the installation surface.
According to the third aspect, the vibration isolator that supports the structure on the installation surface is also a control method, and the vibration isolation device includes an elastic mechanism that supports the structure with respect to the installation surface, and A damper mechanism that suppresses vibration of the structure with respect to the installation surface, a detection unit that detects a position signal corresponding to the relative position of the structure with respect to the installation surface, and a relative position of the structure with respect to the installation surface An adjustment drive unit, and a control unit that generates a drive signal for driving the adjustment drive unit according to the position signal detected by the detection unit, the control unit comprising the mass of the structure, the The first signal generated from the position signal using the first transfer function including at least one of the rigidity of the elastic mechanism and the viscosity proportionality coefficient of the damper of the damper mechanism, the mass of the structure, The rigidity of the elastic mechanism and its A second signal generated from the position signal using a second transfer function that includes at least one of the viscosity proportional coefficients of the damper of the damper mechanism and that is different from the first transfer function. A control method for generating the drive signal is provided.

According to a fourth aspect, there is provided an exposure method for exposing a pattern to an object to be exposed, wherein the relative position with respect to the installation surface of a frame that supports the movable stage and supports the object to be exposed is controlled by a vibration isolator. And an anti-vibration device is controlled by the control method according to the third aspect.
According to a fifth aspect, there is provided a device manufacturing method including a lithography process, in which an object is exposed using the exposure apparatus or exposure method according to the aspect of the present invention.

1 is a diagram illustrating a schematic configuration of an exposure apparatus according to an example of an embodiment, partly in cross section. It is a figure which shows one vibration isolator in FIG. 1, and its control system. It is a figure which shows the dynamic model of the vibration isolator of FIG. (A) is a block diagram showing the vibration isolator of FIG. 3, (B) is a block diagram showing an example of the vibration isolator and the control system. (A) is a block diagram showing a part of the vibration isolator and the control system, and (B) is a block diagram equivalent to FIG. 5 (A) when a predetermined approximation is performed. It is a block diagram which shows a part of vibration isolator and a control system. (A) is a figure which shows a vibration isolation characteristic, (B) is a block diagram which shows a part of a vibration isolator and a control system. (A) is a block diagram showing a part of a vibration isolator and a control system for controlling rigidity, and (B) is a block diagram equivalent to FIG. 8 (A). (A) is a block diagram showing a control system that also performs PI control, and (B) is a block diagram equivalent to FIG. 9 (A). (A) is a figure which shows the amplitude of the transmission characteristic of a vibration isolator, (B) is a figure which shows the phase of the transmission characteristic. (A) is a diagram showing vibration applied to the installation surface, (B) is a diagram showing time response characteristics of the vibration of the structure when passive control is performed, and (C) uses the control system of the embodiment. The figure which shows the time response characteristic of the vibration of the structure in the case of having met, (D) is a figure which shows the time response characteristic of the thrust which an adjustment part produces | generates. (A) is a figure which shows an example of the response characteristic of an amplitude at the time of using the control system of embodiment, (B) is a figure which shows an example of the step time response characteristic in that case. It is a flowchart which shows an example of the usage method of a vibration isolator. It is a flowchart which shows an example of the manufacturing method of an electronic device.

Hereinafter, an exemplary embodiment of the present invention will be described with reference to the drawings.
FIG. 1 shows an exposure apparatus EX according to this embodiment. As an example, the exposure apparatus EX is a scanning exposure type projection exposure apparatus used for manufacturing a liquid crystal display element. In FIG. 1, exposure illumination light IL (exposure light) emitted from, for example, a mercury lamp (not shown) as an exposure light source enters an illumination optical system 10. The illumination optical system 10 includes an optical integrator such as a fly-eye lens, an aperture stop, a condenser lens, a variable blind mechanism (mask blind), a condenser lens system, and the like. The illumination light IL emitted from the illumination optical system 10 irradiates the illumination area of the pattern surface (lower surface) of the mask M with a uniform illuminance distribution.

  An image of the pattern in the illumination area of the pattern surface of the mask M by the projection optical system PL is projected onto a plate P (photosensitive substrate) made of a glass plate coated with a photoresist (photosensitive material). As an example, the projection optical system PL has the same magnification. Note that the magnification of the projection optical system PL may be enlarged or reduced. As the projection optical system PL, a so-called multi-lens projection optical system in which a plurality of partial projection optical systems are arranged in a predetermined arrangement may be used. In this case, the illumination light IL emitted from the illumination optical system 10 illuminates a plurality of illumination areas corresponding to the plurality of partial projection optical systems. Hereinafter, the Z-axis is taken in parallel to the optical axis AX of the projection optical system PL, the X-axis is parallel to the plane of FIG. 1 in the plane perpendicular to the Z-axis, and the Y-axis is perpendicular to the plane of FIG. Take and explain. In the present embodiment, the direction along the X axis (X direction) is the scanning direction of the mask M and the plate P during scanning exposure, and the illumination area on the mask M is along the Y axis, which is the non-scanning direction. The shape is elongated in the direction (Y direction).

  The mask M arranged on the object plane side of the projection optical system PL is held by a mask stage MST that moves at a constant speed in at least the X direction via an air bearing on the mask base 35B during scanning exposure. The movement coordinate position of the mask stage MST (X-direction, Y-direction position, and rotation angle about the Z-axis) is a movable mirror Mr fixed to the mask stage MST and a laser interferometer disposed opposite thereto. (Not shown) and is composed of a linear motor and a fine actuator based on control results from a main control device (not shown) consisting of a computer that comprehensively controls the measurement results and the overall operation of the device. The mask stage MST is driven by a driving system (not shown).

  On the other hand, the plate P disposed on the image plane side of the projection optical system PL is held on the substrate stage PST, and the substrate stage PST can move at a constant speed in at least the X direction during scanning exposure, and in the X direction and the Y direction. It is mounted on the substrate base PB via an air bearing so that it can be stepped. Further, the movement coordinate position of the substrate stage PST (X-direction, Y-direction position, and rotation angle around the Z-axis) is a moving mirror Pr fixed to the substrate stage PST and a laser disposed opposite thereto. A drive system (including a linear motor and a voice coil motor (VCM)) that is sequentially measured by an interferometer (not shown) and based on the measurement result and control information from a main controller (not shown). The substrate stage PST is driven by (not shown).

  The substrate stage PST is also provided with a Z leveling mechanism (not shown) for controlling the position of the plate P in the Z direction (focus position) and the tilt angles around the X and Y axes. An oblique incidence multi-point autofocus sensor (not shown) that measures focus positions (positions in the Z direction) at a plurality of positions on the surface of the plate P is disposed on the lower side surface of the projection optical system PL. . By driving the Z leveling mechanism based on the measurement result of the autofocus sensor, the surface of the plate P is focused on the image plane of the projection optical system PL during scanning exposure.

  Next, an example of a vibration isolation mechanism provided in the exposure apparatus EX will be described. In FIG. 1, for example, a thick flat base member 24 (fixed) as a base member for installing an exposure apparatus via vibration isolators 22 arranged at, for example, four locations on a floor FL of a liquid crystal display manufacturing factory. Board or pedestal). The vibration isolator 22 (mechanism part of the vibration isolator) and the control system 36 constitute an active vibration isolator 20 (see FIG. 2) (details will be described later). The system including the vibration isolator 22 and the control system 36 can also be referred to as an active vibration isolation system (AVIS). Further, a rectangular thin flat plate for installing the main body of the exposure apparatus EX (a portion including the illumination optical system 10 excluding the light source, the mask stage MST, the projection optical system PL, and the substrate stage PST) on the base member 24. A base plate 26 is fixed.

A first frame 35A is placed on the base plate 26 via three or four support members 28 and an anti-vibration table 30, and the projection optical system PL is held in the central opening of the first frame 35A. As the vibration isolation table 30, a vibration isolation table in which the vibration isolation table 22 is downsized can be used.
Further, a flat mask base 35B is fixed via a gate-shaped frame provided at both ends of the first frame 35A, a second frame 35C is fixed so as to cover the mask base 35B, and the second frame 35C The illumination optical system 10 is supported at the center. A mask stage MST for holding the mask M is placed on the mask base 35B. A frame mechanism 34 is constituted by the first frame 35A, the mask base 35B, and the second frame 35C. The frame mechanism 34 holds the projection optical system PL, the mask stage MST (first stage), and the illumination optical system 10 while being supported on the upper surface of the base plate 26 via a plurality of vibration isolation tables 30.

In addition, the substrate base PB is supported on the region surrounded by the plurality of support members 28 on the base plate 26 on the base member 24 via three or four vibration isolation tables 32. A substrate stage PST (second stage) that holds the plate P is placed on the substrate base PB. As the vibration isolation table 32, a vibration isolation table in which the vibration isolation table 22 is downsized can be used.
The vibration isolator 20 including each of the plurality of anti-vibration bases 22 suppresses vibration of almost the entire portion of the exposure apparatus EX including the base member 24 with respect to the floor FL. For this reason, even when vibration from another manufacturing apparatus or the like (not shown) is transmitted to the floor FL, the vibration of the exposure apparatus EX is suppressed, and the exposure apparatus EX can perform exposure with high accuracy. Further, the vibration of the projection optical system PL and the mask stage MST is suppressed by the vibration isolation device including the plurality of vibration isolation tables 30, and the vibration of the substrate stage PST is suppressed by the vibration isolation device including the plurality of vibration isolation tables 32. Is done. Note that at least one of the vibration isolation tables 30 and 32 may be different from the vibration isolation table 22. For example, at least one of the vibration isolation tables 30 and 32 may be a passive vibration isolation table.

  When exposing the plate P using the exposure apparatus EX, irradiation of the illumination light IL to the mask M is started, and a part of the pattern of the mask M is imaged on the plate P through the projection optical system PL. While exposing one shot region, the shot region is moved by a scanning exposure operation in which the mask stage MST and the substrate stage PST are moved synchronously in the X direction with the projection magnification β of the projection optical system PL as a speed ratio (synchronous scanning). The pattern image of the mask M is transferred to the surface. Thereafter, the irradiation of the illumination light IL is stopped, and the step-and-scan method is performed by repeating the operation of stepping the plate P in the X direction and the Y direction via the substrate stage PST and the above-described scanning exposure operation. Thus, the pattern image of the mask M is transferred to the entire shot area of the plate P.

  Next, the vibration isolator 20 including the vibration isolator 22 of this embodiment will be described in detail. In the following, a description will be given of a vibration isolator that suppresses vibration in the Z direction, which is a direction parallel to the optical axis AX of the projection optical system PL in a portion including the base member 24. This is the vibration in the X direction and the Y direction. The present invention can be similarly applied to a mechanism that suppresses vibration, and also to a vibration isolator that suppresses vibration in the rotational direction around the X, Y, and Z axes.

  FIG. 2 shows the vibration isolator 20 including the single vibration isolator 22 and the control system 36 in FIG. In FIG. 2, the base member 24 is supported on a highly rigid support base 38 installed on the floor FL via an air damper 40 and an elastic member 48 having a relatively rigid compression coil spring. The air damper 40 is stably held by the holding member 41 </ b> A on the support base 38 and the holding member 41 </ b> B on the bottom surface of the base member 24. As the elastic member 48, a leaf spring or the like can be used instead of the compression coil spring.

  The air damper 40 as a fluid damper is one in which air as a gas is sealed in a flexible hollow bag in a state where the pressure can be controlled. That is, for example, an air intake portion 42 and an air damper 40 which are ends of a utility pipe (not shown) connected to a compressor (not shown) as a common compressed air source in a factory are, for example, a flexible pipe 43. Connected with. In the middle of the pipe 43, a regulator 44 and a servo valve 45 capable of controlling the air flow rate are mounted. Further, a pressure sensor 46 that measures the pressure of the gas in the air damper 40 is provided, and a detection signal of the pressure sensor 46 is supplied to the control system 36. As an example, the control system 36 controls the flow rate of the servo valve 45 so that the pressure detected by the pressure sensor 46 falls within an allowable range with respect to the target value. A hydraulic damper may be used instead of the air damper 40.

Further, a scale member 52a fixed to the support table 38 and a detection unit 52b fixed to the base member 24 are provided between the support table 38 and the base member 24, and the base member with respect to the support table 38 (floor FL). A position sensor 52 is provided for determining the relative position of 24 in the Z direction (this is x _sns (t)). The position sensor 52 is a non-contact optical sensor that detects a signal corresponding to the relative position x _sns (t), but is not limited thereto. The detection signal of the position sensor 52 is supplied to the control system 36, and using the information such as the detection signal, the control system 36 uses the target position in which the relative position of the base member 24 (exposure apparatus EX) with respect to the floor FL is set in advance. Thus, the thrust of the motor unit 50 is controlled. As the position sensor 52, an electrostatic linear encoder or a linear encoder other than an optical linear encoder can be used. Further, instead of the position sensor 52, an eddy current type displacement sensor, a non-contact type gap sensor, or the like may be used.

Further, a scale member 52a fixed to the support table 38 and a detection unit 52b fixed to the base member 24 are provided between the support table 38 and the base member 24, and the base member with respect to the support table 38 (floor FL). A non-contact optical position sensor 52 is provided for detecting a signal corresponding to a relative position of 24 in the Z direction (this is x _sns (t)). The detection signal of the position sensor 52 is supplied to the control system 36, and using the information such as the detection signal, the control system 36 uses the target position in which the relative position of the base member 24 (exposure apparatus EX) with respect to the floor FL is set in advance. Thus, the thrust of the motor unit 50 is controlled. As the position sensor 52, an electrostatic linear encoder or a linear encoder other than an optical linear encoder can be used. Further, instead of the position sensor 52, an eddy current type displacement sensor, a non-contact type gap sensor, or the like may be used.

  Next, a part for controlling the operation of the motor unit 50 in the control system 36 of the vibration isolator shown in FIG. 2 will be described. FIG. 3 shows a dynamic model of the vibration isolator 22 shown in FIG. 3, the installation surface 16 corresponds to the surface of the floor FL in FIG. 2, and the structure 18 is the base member 24 in FIG. 1 and the mass of the constituent elements of the exposure apparatus EX supported by the base member 24 (this). Is a flat plate-like member having the same mass as M). In FIG. 1, when there are, for example, four vibration isolation tables 22 on the bottom surface of the base member 24, the mass M is the total mass of the components of the exposure apparatus EX supported by the base member 24 and the base member 24. It is almost 1/4.

In FIG. 3, the viscosity proportionality coefficient of the air damper 40 of FIG. 2 is C, and the rigidity of the elastic member 48 is K. At this time, the mass M is a coefficient of resistance (inertia) according to the acceleration of the structure 18, the viscosity proportional coefficient C is a coefficient of resistance according to the speed of the structure 18, and the stiffness (spring constant) K Can be regarded as a coefficient of resistance according to the position of the structure 18.
For example, the position in the Z direction of the installation surface 16 with respect to a predetermined reference surface is x ₀ (t), the position in the Z direction of the structure 18 with respect to the reference surface is x _v (t) (t is time), and the installation surface 16 The relative position in the Z direction of the structure 18 with respect to is set to x _sns (t), and the thrust in the Z direction from the installation surface 16 by the motor unit 50 to the structure 18 is set to f (t). The positions x ₀ (t) and x _v (t) can also be called absolute positions with respect to the relative positions.

FIG. 4A is a block diagram showing a vibration isolator 22 corresponding to the dynamic model of FIG. A block 22B in FIG. 4A corresponds to the dynamic model in FIG. Note that the variable s is a Laplace transform variable. If the frequency is f (Hz) and the angular frequency is ω, s = i2πf = iω (i is an imaginary unit) in a steady state. In the block unit 22B, the thrust f (t) is input to the addition side of the subtraction unit (addition point) 54A, and the output of the subtraction unit 54A is integrated by the integration unit 54D and the displacement unit 54B and the integration unit 54C by the mass M. The signal is supplied to the addition side of the subtraction unit 54E, and the output (position x _v (t)) of the integration unit 54D is supplied to the addition side of the subtraction unit 54F.

Also, supplied to the subtractor and integrator 54H of the subtraction section 54E through the integral portion 54G (2 derivative by time t of the position x ₀ (t)) the acceleration of the mounting surface 16 of Figure 3, the integrator 54H The output (position x ₀ (t)) is supplied to the subtraction side of the subtraction unit 54F, and the output (relative position x _sns (t)) of the subtraction unit 54F is supplied to the elastic unit _54J having rigidity K, and the subtraction unit 54E The output is supplied to a damper 54I having a viscosity proportional coefficient C. The outputs of the elastic portion 54J and the damper portion 54I are added by an adding portion (addition point) 54K, and the output of the adding portion 54K is supplied to the subtracting side of the subtracting portion 54A.

式（１１）において、第２式の２行×２列の行列（以下、行列Ｐ（ｓ）ともいう）中の要素Ｐ₂（ｓ）が防振装置２０の除振特性（後述）を表している。 Further, the following equation (11) is _{obtained by converting} the block portion 22B of FIG. 4A to two outputs (position x _v (t) and x _{sns with} two inputs (thrust f (t) and position x ₀ (t)). (T)) is expressed using a transfer function.

In Expression (11), an element P ₂ (s) in a matrix of 2 rows × 2 columns (hereinafter also referred to as matrix P (s)) of the _second expression represents the vibration isolation characteristics (described later) of the vibration isolator 20. ing.

Next, FIG. 4B is a block diagram showing an example of an active vibration isolator including the control system 36 of the present embodiment. In FIG. 4B, the block unit 22B is a block diagram of the vibration isolation table 22 in FIG. 4A expressed by using the matrix P (s) in the equation (11).
4B, a signal corresponding to the target value r of the relative position in the Z direction with respect to the installation surface 16 of the structure 18 is supplied to the addition side of the subtraction unit 56, and the structure 18 output from the block diagram 22B. A signal corresponding to the relative position x _sns (t) measured by the position sensor 52 is supplied to a subtraction side of the subtraction unit 56 and a feedback control unit (hereinafter referred to as FB control unit) 58. Further, the output e of the subtracting unit 56 is supplied to a control unit (hereinafter referred to as a PI control unit) 60 for performing proportional control and integral control, and the output u of the PI control unit 60 is supplied to the addition side of the subtracting unit 62. Then, the output of the FB control unit 58 is supplied to the subtraction side of the subtraction unit 62, and the output of the subtraction unit 62 (signal f ^ref for generating the thrust f (t)) is the drive circuit unit 50D (this The transfer function of the motor driver characteristic is _QMD (s)), and a thrust f (t) is generated from the motor unit 50. The PI controller 60 can be regarded as a second feedback controller provided separately from the FB controller 58.

The transfer function Q _MD (s) of the motor driver characteristic of the drive circuit unit 50D is a low-pass filter (LPF) characteristic, and the band varies depending on the motor. In the case of a voice coil motor suitable for a relatively small structure, the band is about several kHz. In the case of a pneumatic actuator (such as an air cylinder) suitable for a large structure, the band is up to about 20 Hz. is there.
4B is mainly provided to stably support the structure 18, and the FB control unit 58 is mainly used to improve the vibration isolation rate of the vibration isolator 20. Is provided. As an example, the vibration isolation rate is the ratio of the amount of variation of the position x _v (t) of the structure 18 to the amount of variation of the position x ₀ (t) of the installation surface 16 as follows.
Vibration isolation ratio = x _v (t) / x ₀ (t)
The smaller the vibration isolation ratio, the less the vibration of the structure 18 due to the vibration of the installation surface 16, and the better the vibration isolation performance (vibration isolation characteristics). Hereinafter, as an example, the vibration isolation characteristics or the vibration isolation characteristics of the vibration isolation device 20 are represented by the vibration isolation ratio.

Next, FIG. 5A shows the block unit 22B, the drive circuit unit 50D, the subtraction unit 62, and the FB control unit 58 in FIG. 4B. Further, in FIG. 5A, a block diagram when the transfer function Q _MD (s) of the drive circuit unit 50D is regarded as approximately 1 is shown in FIG. The transfer function C _IPFB (s) of the FB control unit 58 in FIG. 5B is expressed by the following equation (12).
Note that the function P ₁ (s) (function representing the actual mechanical characteristics of the vibration isolator 22) in the expression (12) is expressed by the expression (13), and the function P _n1 (s) is an ideal mechanical characteristic ( The function Q (s) is a function having a low-pass filter characteristic for equalizing the numerator and denominator orders of the transfer function.

Here, the following three cases (hereinafter referred to as case 1, case 2, and case 3) are assumed as functions P _n1 (s) representing ideal mechanical characteristics. In case 1, the function P _n1 (s) is set to ideal values M _n , C _n , and K _n for the mass M, the viscosity proportional coefficient C, and the stiffness K, respectively, as shown in the following equation (14A). Function. At this time, the transfer function C _IPFB (s) of the FB control unit 58 is expressed by Expression (14B), and the function Q (s) in Expression (14B) is expressed by using the cutoff angular frequency ω _LPF and the attenuation rate ζ. (14C).

In case 2, the function P _n1 (s) is a function in which the viscosity proportional coefficient C and the stiffness K are set to ideal values C _n and K _n , respectively, as shown in the following equation (15A). is there. At this time, the transfer function C _IPFB (s) of the FB control unit 58 is expressed by Expression (15B), and the function Q (s) in Expression (15B) is expressed by Expression (15C) using the cutoff angular frequency ω _LPF. expressed.

In case 3, the function P _n1 (s) is a function in which only the stiffness K is set to an ideal value K _n as shown by the following equation (16A). At this time, the transfer function C _IPFB (s) of the FB control unit 58 has a simple form as a difference between the constant K _n and the constant K, as shown in Expression (16B).

FIG. 6 is a block diagram of the vibration isolator 20 similar to FIG. However, the matrix P (s) is expressed by the above equation (11). In FIG. _6A , the change in the relative position x _sns (t) with respect to the change in the target input u to the subtractor 62 is Pn1 (s), and the vibration isolation characteristic (vibration isolation rate = x _v (t) / x ₀ (t)) is a function P _n2 (s). When this function P _n2 (s) is used, the vibration isolation characteristics (vibration isolation ratio) in the case 1, case 2, and case 3 described above are expressed by the following equations (17A), (17B), and (17C). expressed.

Next, FIG. 7A shows vibration isolation characteristics corresponding to the block diagram of FIG. 7B (same as the block diagram of FIG. 5B), and the horizontal axis of FIG. ), The vertical axis represents the vibration isolation rate (dB). Further, a straight line A1 in FIG. 7A represents the limit of vibration isolation characteristics (= C / (Ms)) determined by the viscosity proportional coefficient C and mass M, and a curve A2 represents the vibration isolation table 22 itself. 7 represents a vibration characteristic (= (Cs + K) / (Ms ² + Cs + K)), and a curve A3 represents the transfer function C _IPFB (s) of the FB control unit 58 in the block diagram of FIG. 3) as well as shows a vibration isolation characteristics when expressed in the difference between the just constant K _n and a constant K as follows.
C _IPFB (s) = K _n −K <0 (17D)

In this case, since the target stiffness K _n is set to a value smaller than the actual stiffness K, the transfer function C _IPFB (s) is a negative constant, and the control using the FB control unit 58 is a positive proportional control. Become. In FIG. 7A, in order to change the characteristics of the high frequency region A4 of the curve A3 with the thrust of the motor unit 50, the power of the motor unit 50 is increased and the response characteristic of the drive circuit unit 50D is increased. do it. Further, since it is better not to change the straight line A1, the rigidity K is changed in a smaller direction as in the case 3 described above so as to lower the resonance frequency of the vibration isolation characteristics.

When the transfer function C _IPFB (s) of the FB control unit 58 is set as shown in Expression (17D), the block diagram of FIG. 5B (FIG. 7B) is shown in FIG. It becomes like A). 8A, the part other than the elastic part 54J in the block part 22B in FIG. 4A is represented by a block part 22B1 having a transfer function (1 / (Ms ² + Cs)) and a subtracting part 54A. . The elastic part 54J and the block part 22B1 are in parallel.

In FIG. 8A, since the FB control unit 58 is connected in parallel with the elastic unit 54J via the subtraction unit 62, FIG. 8A is equivalent to the equivalent circuit 64 of FIG. 8B. FIG. 8B means that in the actual block portion 22B1 representing the vibration isolator 22, the elastic portion 54J having the rigidity K is replaced with the elastic portion 54J1 having the smaller rigidity K _n . As described above, the transfer function of the part including the block unit 22B (or 22B1) indicating the anti-vibration table 22 and the FB control unit 58 is substantially equal to the transfer function of the anti-vibration table 22 in which the stiffness K is changed to another value. This is referred to as electrically converting the rigidity K of the vibration isolator 22 into a target value. As a result, the vibration-proof characteristic is improved from the curve A2 (mechanical characteristic) to the curve A3 (ideal characteristic) in FIG.

  Similarly, at least one of the mass K, the viscosity proportional coefficient C, and the stiffness K can be changed to another value in the transfer function of the portion including the block unit 22B (or 22B1) indicating the vibration isolation table 22 and the FB control unit 58. The mechanical characteristics of the vibration isolator 20 represented by the mass K, the viscosity proportional coefficient C, and the stiffness K of the vibration isolator 22 are substantially the same (equivalent) as the transfer function of the vibration isolator 22. Is electrically converted to the target characteristics.

Next, the PI control unit 60 in FIG. 4B will be described.
FIG. 9A is the same block diagram as FIG. 4B. In FIG. 9A, the transfer function C _PI (s) of the PI control unit 60 is set to K _p + K _i / s (K _p And _Ki are gains of proportional control and integral control). At this time, FIG. 9A is equivalent to FIG. A block unit 22B2 in FIG. 9B corresponds to the block unit 22B, the subtracting unit 62, and the FB control unit 58 in FIG. 9A. In this case, the PI control unit 60 controls the thrust f (t) of the motor unit 50 so that the relative position x _sns (t) of the structure 18 with respect to the installation surface 16 is maintained at the target value r. Further, the gains (K _p and K _i ) of the PI control unit 60 are adjusted so that a desired target value response characteristic (for example, 1 Hz or less) is obtained.

FIGS. 10A (amplitude) and (B) (phase) show the transfer of the transfer function P ₁ (s) Q _MD (s) in FIG. 9B in the simulation using the control system 36 of this embodiment. Show properties. The horizontal axis of FIG. 10 (A) and (B) is a frequency (Hz). In this case, the mass M of the vibration isolator 22 is 500 kg, the viscosity proportionality coefficient C is 2ζωM (N / (m / s)), the stiffness K is ω ² M (N / m), the damping rate ζ is 0.2, and the angle The frequency ω was 2π5 (rad / s). Further, the attenuation rate ζ _MD of the transfer characteristic of the drive circuit unit 50D is 0.7, the angular frequency ω _MD is 2π2000 (rad / s), and the rigidity K _{n in} the case 3 of the FB control unit 58 is ω _n ² M ( N / m) and ω _n were 2π1.

At this time, the vibration isolation characteristic was as shown by a curve A3 in FIG. Further, the vibration at the position x ₀ of the installation surface 16 is shown in FIG. At this time, the position x _v (t) of the structure 18 when the FB control unit 58 is not provided is as shown in FIG. 11B, and the position x _v (t) of the structure 18 when the FB control unit 58 is provided is FIG. 11C shows that the vibration isolation rate is greatly improved. Further, the setting value f _{ref of the} thrust supplied to the drive circuit unit 50D is as shown in FIG. _11D , and it can be seen that the thrust f is accurately applied to the structure 18 from the motor unit 50.

FIG. 12A shows an example of a simulation result of target value response characteristics when the PI control unit 60 is provided. In FIG. 12A, the horizontal axis represents frequency (Hz) and the vertical axis represents amplitude. FIG. 12B shows an example of the simulation result of the step response time of the target value of 1 mm when the PI control unit 60 is provided. In FIG. 12B, the horizontal axis represents time (s), the vertical axis represents position (mm), the dotted line represents the target position r, and the solid line represents the actual relative position x _sns . 12 (A) and 12 (B), it can be seen that a desired (about 1 Hz) target value response characteristic can be obtained.

Next, an example of a control method (usage method) of the vibration isolator 20 of the present embodiment will be described with reference to the flowchart of FIG. First, in step 102 of FIG. 13, the transmission characteristic of the FB control unit 58 of FIG. 4B is converted so that the rigidity K of the block unit 22B corresponding to the vibration isolation table 22 is substantially reduced to a value K _n. Set. Then, the relative position x _sns of the structure 18 with respect to the installation surface 16 is measured by the position sensor 52 (step 104), and the motor unit 50 is applied to the installation surface 16 so that the difference between the measured value and the target value becomes small. Then, the structure 18 is driven (step 106). By repeating the operations of Steps 104 and 106 until vibration isolation is stopped (Step 108), even if the installation surface 16 vibrates, the vibration of the structure 18 is suppressed by the vibration.
According to this control method, the vibration isolation performance (vibration isolation rate and the like) can be improved without increasing the number of measuring devices for measuring the relative position of the structure 18 (vibration isolation object) and the structure. The target value response characteristic of the object 18 can be improved.

As described above, the exposure apparatus EX of the present embodiment includes the vibration isolator 20. And the vibration isolator 20 is the elastic member 48 (elasticity) which supports the structure 18 with respect to the installation surface 16 in the vibration isolator which supports the structure 18 (base member 24) on the installation surface 16 (floor FL). Mechanism), an air damper 40 (damper mechanism) that suppresses vibration of the structure 18 with respect to the installation surface 14, and a position sensor 52 (detection unit) that detects a position signal corresponding to the relative position x _sns of the structure 18 with respect to the installation surface 14. ), A motor unit 50 (adjustment unit) that adjusts the relative position of the structure 18 with respect to the installation surface 14, and a control system 36 that drives the motor unit 50 in accordance with a position signal detected by the position sensor 52. The control system 36 changes the rigidity K of the elastic member 48 that supports the structure 18 to a smaller (target characteristic) electrical value (as a transfer function) (see FIG. 8A). (Characteristic change Part).

According to the present embodiment, as an anti-vibration performance, for example, without increasing the number of measuring devices (for example, a gyro sensor or an acceleration sensor) for measuring the absolute position or the like of the structure 18 (anti-vibration target). The vibration isolation ratio (position x _v of the structure 18 / position x _{0 of the} installation surface 16) can be improved. Moreover, the manufacturing cost of the vibration isolator 20 can be suppressed.
Further, the control system 36 includes a target position signal corresponding to the target position r of the structure 18 and a subtraction unit 56 that drives the motor unit 50 according to the difference between the position signal and the FB control unit 58. This is a negative feedback unit that feeds back a signal obtained by converting the position signal in accordance with the target characteristic between the output unit of the control system 36 and the input unit of the motor unit 50. In this case, the target value response characteristic of the structure 18 (the relative position of the structure 18 with respect to the installation surface 16 is within an allowable range with respect to the target value by the first feedback system including the first feedback unit. (Response characteristics when maintaining) can be improved. Further, the anti-vibration performance (vibration isolation rate) can be improved by the second feedback system including the FB control unit.

Further, when the transfer function of the FB control unit 58 is a difference between the target rigidity K _n and the original rigidity K, the vibration isolator 22 is set to the target value of the rigidity K with a simple configuration. It can be electrically converted to a variable vibration isolation table, improving the vibration isolation performance.
Further, the control system 36 drives the motor unit 50 in accordance with a target position signal corresponding to the target position of the structure 18, a proportional signal proportional to the difference between the position signal, and an integral signal obtained by integrating the difference. When the PI control unit 60 (calculation unit) is included, the target value response characteristics of the structure 18 can be further improved.

  The exposure apparatus EX is an exposure apparatus that exposes the pattern of the mask M onto the plate P (object to be exposed), and supports the frame mechanism 34 (frame) and the plate P and moves relative to the frame mechanism 34. A possible substrate stage PST and a vibration isolator 20 are provided, and the vibration isolator 20 controls the relative position of the frame mechanism 34 (base member 24) with respect to the floor FL (installation surface) within an allowable range with respect to the target position. ing.

  Further, in the exposure method of exposing the plate P using the exposure apparatus EX, the above-described control method of the image stabilizer 20 is used during the exposure. According to the exposure apparatus EX or the exposure method, since the vibration isolation performance of the vibration isolator 20 is improved, the plate P can be exposed with high accuracy.

(Modification)
In the above-described embodiment, the following modifications are possible.
In the above-described embodiment, the PI control unit 60 is provided in the control system 36. However, the PI control unit 60 may perform only at least one of proportional control and integral control. Further, the PI control unit 60 may perform differential control (output a differential signal of the input signal to the subtracting unit 62) together with the proportional control and the integral control or instead of the proportional control and the integral control.
However, the PI control unit 60 can be omitted in the control system 36.

Further, the transfer function of the FB control unit 58 may be a linear function (equation (15)) with respect to the frequency of the denominator and the numerator. In this case, the anti-vibration table 22 can be electrically converted into an anti-vibration table in which the viscosity proportionality coefficient C and the stiffness K are respectively changed to target values, and the anti-vibration performance can be improved.
Furthermore, the transfer function of the FB control unit 58 includes a first function (P _n1 ⁻¹ (s)) in which the denominator and the numerator of the transfer function P _n1 (s) corresponding to the target characteristic are interchanged, and the image stabilization. A first transfer function comprising a difference between a denominator of the transfer function P ₁ (s) corresponding to the mechanical characteristics of the apparatus and a second function (P ₁ ^-1 (s)) in which the numerator is replaced; _May be a transfer function (function C _IPFB (s) in equation (14B)) represented by a product of the second transfer function Q (s) corresponding to the low-pass filter. In the case of having this transfer function, the vibration isolation table 22 can be electrically converted into a vibration isolation table in which at least one of the mass M, the viscosity proportional coefficient C, and the stiffness K is changed to a target value. Vibration performance can be improved.

  In the present embodiment, the case where the adjustment unit is the motor unit (VCM) 50 illustrated in FIG. 2 has been described as an example. However, the present invention is not limited to this. For example, the damper mechanism 40 may be used as the adjustment unit without using the VCM. In that case, an actuator for adjustment may be provided on the regulator of the damper mechanism and the servo valve capable of controlling the air flow rate, and the vibration isolator may be configured using the actuator as an adjustment unit.

(Device manufacturing method)
A liquid crystal display element or the like is formed by forming a predetermined pattern (circuit pattern, electrode pattern, etc.) on the substrate (plate P) using the exposure apparatus of each of the above-described embodiments or the exposure method using these exposure apparatuses. The liquid crystal device can be manufactured. Hereinafter, an example of this manufacturing method will be described with reference to steps S401 to S404 in FIG.

  In step S401 (pattern formation process) in FIG. 14, first, a liquid crystal display is applied using a coating process in which a photoresist is coated on a substrate to be exposed to prepare a photosensitive substrate (plate P), and the above exposure apparatus or exposure method. An exposure process for transferring and exposing the pattern of the mask for the element onto the photosensitive substrate and a developing process for developing the photosensitive substrate are performed. A predetermined resist pattern is formed on the substrate by a lithography process including the coating process, the exposure process, and the development process. Following this lithography process, a predetermined pattern including a large number of electrodes and the like is formed on the substrate through an etching process using the resist pattern as a processing mask, a resist stripping process, and the like. The lithography process or the like is executed a plurality of times according to the number of layers on the plate P.

  In the next step S402 (color filter forming step), a large number of three fine filter sets corresponding to red R, green G, and blue B are arranged in a matrix, or red R, green G, and blue B are arranged. A color filter is formed by arranging a set of three stripe-shaped filters in the horizontal scanning line direction. In the next step S403 (cell assembly process), for example, liquid crystal is injected between the substrate having the predetermined pattern obtained in step S401 and the color filter obtained in step S402, and a liquid crystal panel (liquid crystal cell) is obtained. ).

  In subsequent step S404 (module assembly process), the liquid crystal panel (liquid crystal cell) thus assembled is attached with an electric circuit for performing a display operation and components such as a backlight to complete a liquid crystal display element. Let According to the above-described method for manufacturing a liquid crystal display element, the vibration isolation performance of the vibration isolation device 20 is improved with a simple configuration, and the exposure accuracy in the exposure apparatus or the exposure method can be increased. And it can be manufactured at low cost.

  The present invention is not limited to application to a manufacturing process of a liquid crystal display element. For example, a manufacturing process of a display device such as a plasma display, an imaging element (CCD or the like), a micromachine, a MEMS (Microelectromechanical Systems: It can be widely applied to manufacturing processes of various devices such as micro electromechanical systems), thin film magnetic heads using ceramic wafers or the like as substrates, and semiconductor elements.

  The present invention can also be applied to the case where image stabilization is performed with an immersion type exposure apparatus disclosed in, for example, US Patent Application Publication No. 2007/242247. Further, the present invention provides vibration isolation with a projection exposure apparatus that uses extreme ultraviolet light (EUV light) having a wavelength of about several nm to 100 nm as an exposure beam, and a proximity type or contact type exposure apparatus that does not use a projection optical system. It can also be applied when performing.

Furthermore, the present invention can also be applied to the case of performing vibration isolation for equipment other than the exposure apparatus, such as a defect inspection apparatus, a photosensitive material coater / developer, and the like.
As described above, the present invention is not limited to the above-described embodiment, and various configurations can be taken without departing from the gist of the present invention.

EX ... exposure apparatus, FL ... floor, 20 ... vibration isolation device, 16 ... installation surface, 18 ... structure, 22 ... vibration isolation table, 24 ... base member, 36 ... control system, 40 ... air damper, 48 ... elastic member, 50 ... Motor unit, 52 ... Position sensor, 58 ... FB control unit (feedback control unit), 60 ... PI control unit

Claims (16)

In the vibration isolator that supports the structure on the installation surface,
An elastic mechanism for supporting the structure with respect to the installation surface;
A damper mechanism for suppressing vibration of the structure relative to the installation surface;
A detection unit for detecting a position signal corresponding to a relative position of the structure with respect to the installation surface;
An adjustment unit for adjusting the relative position of the structure with respect to the installation surface;
A control unit that generates a drive signal for driving the adjustment unit according to a position signal detected by the detection unit,
The control unit is generated using a first transfer function including at least one of the mass of the structure, the rigidity of the elastic mechanism, and the viscosity proportionality coefficient of the damper of the damper mechanism and the position signal. A second transfer function that includes at least one of the first signal, the mass of the structure, the rigidity of the elastic mechanism, and the viscosity proportionality coefficient of the damper of the damper mechanism, and is different from the first transfer function And a second signal generated using the position signal, and a vibration isolator that generates the drive signal.   2. The image stabilization device according to claim 1, wherein the control unit generates the first signal by using the first transfer function from a difference between a target position signal corresponding to a target position of the structure and the position signal. apparatus.   The second transfer function includes a first function obtained by replacing a denominator and a numerator of a transfer function corresponding to a target characteristic of the vibration isolator, and a denominator and a numerator of a transfer function representing the vibration isolator. The vibration isolator according to claim 1 or 2, represented by a product of a third transfer function consisting of a difference from the replaced second function and a fourth transfer function corresponding to a predetermined low-pass filter. The target characteristic is a characteristic having a rigidity smaller than the rigidity of the elastic mechanism,
The prevention according to claim 3, wherein the second signal is generated from a signal obtained by multiplying the position signal by a difference between a rigidity of the elastic mechanism and a target rigidity using the second transfer function. Shaker. The target characteristic is a characteristic having a different stiffness from the stiffness of the elastic mechanism and a viscosity proportionality coefficient different from the viscosity proportionality coefficient of the damper of the damper mechanism,
The anti-vibration device according to claim 3, wherein the second transfer function is such that the denominator and the numerator are linear functions with respect to time. The target characteristic is a characteristic having a mass different from the mass of the structure, a rigidity different from the rigidity of the elastic mechanism, and a viscosity proportional coefficient different from the viscosity proportional coefficient of the damper of the damper mechanism,
The vibration isolator according to claim 3, wherein the second transfer function is a quadratic function with respect to time in the denominator and the numerator.   The control unit uses the target position signal corresponding to the target position of the structure, the proportional signal proportional to the difference between the position signal, and the integral signal obtained by integrating the difference to use the first signal. The vibration isolator as described in any one of Claim 1 to 6 which has the calculating part to produce | generate.   The vibration isolator according to any one of claims 1 to 7, wherein the damper mechanism is a damper using a fluid.   The vibration isolator according to any one of claims 1 to 8, wherein the adjustment unit is an electromagnetic or fluid actuator. An exposure apparatus that exposes a pattern onto an object to be exposed,
Frame,
A stage that supports the object to be exposed and is movable relative to the frame;
A vibration isolator according to any one of claims 1 to 9,
An exposure apparatus that controls a relative position of the frame with respect to an installation surface by the vibration isolator. A vibration isolator that supports the structure on the installation surface is also a control method,
The vibration isolator is
An elastic mechanism for supporting the structure with respect to the installation surface;
A damper mechanism for suppressing vibration of the structure relative to the installation surface;
A detection unit for detecting a position signal corresponding to a relative position of the structure with respect to the installation surface;
An adjustment drive for adjusting the relative position of the structure with respect to the installation surface;
A control unit that generates a drive signal for driving the adjustment drive unit according to the position signal detected by the detection unit,
The control unit is generated from the position signal using a first transfer function including at least one of a mass of the structure, a rigidity of the elastic mechanism, and a viscosity proportionality coefficient of the damper of the damper mechanism. A second transfer function that includes at least one of the first signal, the mass of the structure, the rigidity of the elastic mechanism, and the viscosity proportionality coefficient of the damper of the damper mechanism, and is different from the first transfer function And a second signal generated from the position signal, and a control method for generating the drive signal.   The first function in which the denominator and numerator of the transfer function corresponding to the target characteristic of the vibration isolator are replaced, and the denominator and numerator of the transfer function corresponding to the mechanical characteristic of the vibration isolator are replaced. Generating the drive signal using a third transfer function that is a difference from the second function and a transfer function represented by a product of a fourth transfer function corresponding to a predetermined low-pass filter. The control method of Claim 11 containing. The target characteristic is a characteristic having a rigidity smaller than the rigidity of the elastic mechanism,
The relative position of the structure relative to the installation surface using a signal obtained by multiplying the position signal corresponding to the relative position of the structure relative to the installation surface by the difference between the rigidity of the elastic mechanism and the target rigidity. The control method according to claim 12, further comprising controlling An exposure method for exposing a pattern to an object to be exposed,
Controlling the relative position with respect to the installation surface of the frame that supports the movable stage by supporting the object to be exposed with a vibration isolator;
Controlling the vibration isolator by the control method according to any one of claims 11 to 13,
An exposure method comprising: A device manufacturing method including a lithography process,
A device manufacturing method for exposing an object using the exposure apparatus according to claim 10 in the lithography process. A device manufacturing method including a lithography process,
The device manufacturing method which exposes an object using the exposure method of Claim 14 in the said lithography process.

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