JP2009002509A - Vibration isolator - Google Patents

Abstract

When a gas damper is used, vibration isolation performance is improved when the pressure fluctuation or flow rate fluctuation of a gas supply source for the gas damper is large.
In a vibration isolator having an air intake portion and an air damper that supports a structure, a servo valve that controls the flow rate of air supplied from the air intake portion and supplies the air damper to the air damper is provided. A control unit 76 that controls the internal pressure of the air damper 43 via the servo valve 47 based on the position information of the structure and a position variation of the structure due to a pressure variation of the air supplied from the air intake unit 45 are suppressed. In addition, a feedforward unit 65 that applies thrust to the structure is provided.
[Selection] Figure 5

Description

  The present invention relates to an anti-vibration technique for suppressing vibration using a gas damper when supporting a structure, for example, to support an exposure apparatus used when manufacturing various devices such as semiconductor devices and liquid crystal displays. It is suitable for.

  For example, in a lithography process which is one of the manufacturing processes of a semiconductor device, a pattern formed on a reticle (or a photomask) is transferred and exposed on a wafer (or a glass plate) coated with a photoresist. An exposure apparatus such as a batch exposure type (stationary exposure type) projection exposure apparatus such as a stepper or a scanning exposure type projection 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 exposure apparatus is placed between the exposure apparatus and the floor (installation surface). Has a vibration isolator. As a conventional vibration isolator, a mechanism that supports a stage or the like with an air damper that is supplied with air in an open loop so that the internal pressure is maintained substantially constant is widely used. In addition, an active vibration isolator that uses an actuator that suppresses vibration detected by an acceleration sensor or the like disposed on a stage or the like in combination with an air damper has been used. Furthermore, an active vibration isolator that controls the pressure using a detection result of a motion sensor provided on a stage has also been proposed for an air damper (see, for example, Patent Document 1).
JP 2002-175122 A

  Also in an active vibration isolator having a conventional air damper, similarly to an open loop air damper, for example, compressed air supplied from a utility pipe in a factory is used as the gas supplied to the air damper. However, the compressed air supplied from the utility pipe of the factory has a large pressure fluctuation, and there has been a problem that the position fluctuation of the exposure apparatus supported via the vibration isolator arises due to the pressure fluctuation.

In addition, even when the flow rate of compressed air supplied from the utility piping varies, there is a possibility that the position of the exposure apparatus supported via the anti-vibration table may vary due to the variation of the flow rate.
In view of such a point, the present invention provides an active vibration isolation technique that can improve vibration isolation performance when there is a large variation in pressure or flow rate of a gas supply source for a gas damper when using a gas damper such as an air damper. The purpose is to provide.

  The vibration isolator according to the present invention is supplied from the gas supply source in the vibration isolator having a gas supply source for supplying gas and a gas damper for supplying the gas and supporting the structure on the installation surface. Control unit for controlling the flow rate of gas to be supplied to the gas damper, a position information sensor for measuring position information of the structure, and a gas state for measuring the state of gas supplied from the gas supply source A sensor, a first control unit that controls the pressure of the gas in the gas damper via the flow rate control unit based on the position information measured by the position information sensor, and the gas measured by the gas state sensor A second control unit that applies thrust to the structure with respect to the installation surface so as to suppress the position fluctuation of the structure due to the state fluctuation of the gas supplied from the gas supply source based on the state. Tama It is.

  According to the present invention, when active vibration isolation is performed using a gas damper, the second is applied so as to suppress position fluctuations caused by gas state fluctuations such as pressure fluctuations or flow fluctuations of the gas supply source. Thrust can be given to the structure by the control unit. Therefore, the vibration isolation performance when the fluctuation of the pressure or flow rate of the gas supply source is large can be improved.

[First Embodiment]
A preferred first embodiment of the present invention will be described below with reference to FIGS. In this example, the present invention is applied to the case of performing vibration isolation of a scanning exposure type projection exposure apparatus (scanning type exposure apparatus) composed of a scanning stepper (scanner).
FIG. 1 is a block diagram showing functional units constituting the projection exposure apparatus of this example. In FIG. 1, a chamber for housing the projection exposure apparatus is omitted. In FIG. 1, a laser light source 1 made of an ArF excimer laser (wavelength 193 nm) is used as a light source for exposure. As a light source for the exposure, an ultraviolet pulse laser light source such as a KrF excimer laser light source (wavelength 248 nm), an F ₂ laser light source (wavelength 157 nm), a harmonic generation light source of a YAG laser, a harmonic wave of a solid laser (semiconductor laser, etc.) A generator or a mercury lamp (i-line etc.) can also be used.

  Illumination light (exposure light) IL for exposure from the laser light source 1 is a homogenizing optical system 2 composed of a lens system and an optical integrator, a beam splitter 3, a variable dimmer 4 for adjusting light quantity, and a mirror 5. The reticle blind mechanism 7 is irradiated with a uniform illuminance distribution through the relay lens system 6. Illumination light IL limited to a slit shape or a rectangular shape by the reticle blind 7 is irradiated onto the reticle R (mask) through the imaging lens system 8, and an image of the opening of the reticle blind 7 is formed on the reticle R. Imaged. An illumination optical system 9 is configured including a homogenizing optical system 2, a beam splitter 3, a variable dimmer 4 for adjusting light quantity, a mirror 5, a relay lens system 6, a reticle blind mechanism 7, and an imaging lens system 8. Yes.

  Of the circuit pattern region formed on the reticle R, an image of a portion irradiated with illumination light is formed on a substrate (photosensitive) via a projection optical system PL having a bilateral telecentricity and a projection magnification β of a reduction magnification (for example, ¼). An image is projected onto the wafer W coated with a photoresist as a substrate. As an example, the field diameter of the projection optical system PL is about 27 to 30 mm. 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 this example, the direction along the Y axis (Y direction) is the scanning direction of the reticle R and the wafer W during scanning exposure, and the illumination area on the reticle R is the direction along the X axis, which is the non-scanning direction. The shape is elongated in the (X direction).

  First, the reticle R arranged on the object plane side of the projection optical system PL is held on a reticle stage RST that moves at a constant speed in at least the Y direction via an air bearing on a reticle base (not shown) during scanning exposure. . The movement coordinate position of the reticle stage RST (X-direction, Y-direction position, and rotation angle around the Z-axis) is a movable mirror Mr fixed to the reticle stage RST and a laser interferometer disposed opposite thereto. Measurement is sequentially performed with the system 10, and the movement is performed by a drive system 11 including a linear motor, a fine actuator, and the like. The movable mirror Mr and the laser interferometer system 10 actually constitute a triaxial laser interferometer having at least one axis in the X direction and two axes in the Y direction. The measurement information of the laser interferometer system 10 is supplied to a stage control unit 14, and the stage control unit 14 uses the measurement information and control information (input information) from a main control system 20 comprising a computer that controls the overall operation of the apparatus. Based on this, the operation of the drive system 11 is controlled.

  On the other hand, wafer W disposed on the image plane side of projection optical system PL is held on wafer stage WST via a wafer holder (not shown), and wafer stage WST can move at a constant speed in at least the Y direction during scanning exposure. , It is mounted on a wafer base (not shown) via an air bearing so that it can be moved stepwise in the X and Y directions. Further, the movement coordinate position (X direction, Y direction position, and rotation angle around the Z axis) of wafer stage WST is fixed to reference mirror Mf fixed to the lower part of projection optical system PL and wafer stage WST. The moving mirror Mw and the laser interferometer system 12 arranged opposite to the moving mirror Mw are sequentially measured, and the movement is performed by a drive system 13 including an actuator such as a linear motor and a voice coil motor (VCM). . The movable mirror Mw and the laser interferometer system 12 actually constitute a triaxial laser interferometer having at least one axis in the X direction and two axes in the Y direction. Measurement information of the laser interferometer system 12 is supplied to the stage control unit 14, and the stage control unit 14 controls the operation of the drive system 13 based on the measurement information and control information from the main control system 20.

  Wafer stage WST is also provided with a Z leveling mechanism that controls the position (focus position) of wafer W in the Z direction and the tilt angles around the X and Y axes. A projection optical system 23A that projects a slit image onto a plurality of measurement points on the surface of the wafer W and a light receiving optical system 23B that receives reflected light from the surface are formed on the lower side surface of the projection optical system PL. An oblique incidence type multi-point autofocus sensor 23 (projection optical system 23A, light receiving optical system 23B) for measuring defocus amounts at the plurality of measurement points is arranged. Based on the measurement information of the autofocus sensor 23, the stage control unit 14 uses the autofocus method to adjust the wafer stage WST so that the defocus amount and the tilt angle deviation amount of the wafer W are within predetermined control accuracy during scanning exposure. The Z leveling mechanism inside is driven.

  Further, when the laser light source 1 is an excimer laser light source, a laser control unit 25 under the control of the main control system 20 is provided, and this control unit 25 is used for a pulse oscillation mode (one pulse) of the laser light source 1. Mode, burst mode, standby mode, etc.) and the average amount of pulsed laser light emitted is adjusted. The light quantity control unit 27 is variably dimmed so as to obtain an appropriate exposure amount based on a signal from a photoelectric detector 26 (integrator sensor) that receives a part of the illumination light divided by the beam splitter 3. The apparatus 4 is controlled, and the intensity (light quantity) information of the pulse illumination light is sent to the laser control unit 25 and the main control system 20.

  In FIG. 1, irradiation of the reticle R with the illumination light IL is started, and an image of a part of the pattern of the reticle R through the projection optical system PL is projected onto one shot area on the wafer W. The pattern image of the reticle R is transferred to the shot area by the scanning exposure operation in which the reticle stage RST and the wafer stage WST are moved (synchronously scanned) in synchronization with the Y direction using the projection magnification β of the projection optical system PL as the speed ratio. Is done. Thereafter, the irradiation of the illumination light IL is stopped, and the step-and-scan method is performed by repeating the operation of moving the wafer W stepwise in the X and Y directions via the wafer stage WST and the above-described scanning exposure operation. Thus, the pattern image of the reticle R is transferred to all shot areas on the wafer W.

For this exposure, it is necessary to align the reticle R and the wafer W in advance. Therefore, the projection exposure apparatus of FIG. 1 includes a reticle alignment system (RA system) 21 for setting the reticle R at a predetermined position and an off-axis alignment system 22 for detecting marks on the wafer W. Is provided.
Next, an example of an installation state of the projection exposure apparatus of this example in a semiconductor device manufacturing factory will be described. FIG. 2 shows an example of the installation state of the projection exposure apparatus. In FIG. 2, a thick flat pedestal 32 as a base member for installing a projection exposure apparatus is provided on a floor FL of the manufacturing plant via a plurality of (for example, four or more) columns 31 made of, for example, H-shaped steel. A rectangular thin flat plate base plate 33 for installing a projection exposure apparatus is fixed on the pedestal 32.

  A first column 36 is placed on the base plate 33 via three or four support members 34 and an active vibration isolation table 35 (mechanism portion of the vibration isolation device), and an opening in the center of the first column 36. The projection optical system PL is held. The anti-vibration table 35 includes an air damper (gas damper) and an electromagnetic damper including a voice coil motor, as will be described later, and includes a set of acceleration sensors 40 and a set of position sensors installed in the first column 36. By controlling the air pressure (internal pressure) in the air damper and the thrust of the electromagnetic damper based on the detection information (not shown), vibration isolation of the first column 36 (and the member supported thereby) is achieved. Actively done. In this case, vibration isolation in a relatively low frequency region is performed by the air damper, and vibration isolation in a relatively high frequency region is performed by the electromagnetic damper.

  As the acceleration sensor 40, a piezoelectric acceleration sensor that detects a voltage generated by a piezoelectric element (piezo element or the like), or a semiconductor type that utilizes a change in the logical threshold voltage of a CMOS converter according to the magnitude of strain, for example. Can be used. As the position sensor (or displacement sensor), for example, an eddy current displacement sensor can be used. In this eddy current displacement sensor, for example, an alternating current is applied to a coil wound around an insulator, and when the coil is brought close to a measuring object made of a conductor, an eddy current is generated in the conductor by an alternating magnetic field generated by the coil. Take advantage of what happens. That is, the magnetic field due to the eddy current is in the opposite direction to the magnetic field due to the current of the coil, and the intensity and phase of the current flowing through the coil changes as these two magnetic fields overlap. Since this change becomes larger as the measurement object is closer to the coil, the position or displacement of the measurement object can be detected in a non-contact manner by detecting a signal corresponding to the current flowing through the coil. As other position sensors, a capacitance-type non-contact displacement sensor that detects the distance in a non-contact manner by utilizing that the capacitance is inversely proportional to the distance between the sensor electrode and the measurement target, An optical sensor or the like that detects the position of the light beam using a PSD (semiconductor position detector) can also be used.

  Further, a reticle base 37 is fixed to the upper part of the first column 36, a second column 38 is fixed so as to cover the reticle base 37, and the illumination optical system 9 of FIG. The illumination system subchamber 39 is fixed. In this case, the laser light source 1 of FIG. 1 is installed on the floor FL outside the pedestal 32 of FIG. 2 as an example, and the illumination light IL emitted from the laser light source 1 is illuminated via a beam transmission system (not shown). Guided to the optical system 9. A reticle stage RST that holds the reticle R is placed on the reticle base 37. In FIG. 2, a column structure CL is constituted by a first column 36, a reticle base 37, and a second column 38. The column structure CL is supported on the upper surface (installation surface) of the pedestal 32 via a plurality of active vibration isolation tables 35, the projection optical system PL, the reticle stage RST (first stage), and the illumination The optical system 9 is held.

The above-described set of acceleration sensors 40 includes, for example, three Z-axis acceleration sensors that measure acceleration in the Z direction at three locations that are not substantially on the same line in the XY plane, and two X-direction acceleration sensors that are separated in the Y direction. Are comprised of two X-axis acceleration sensors that measure the acceleration in the Y direction, and two Y-axis acceleration sensors that measure the acceleration in the Y direction at two locations separated in the X direction. The acceleration sensor 40 measures the acceleration in the X direction, Y direction, and Z direction of the column structure CL and the rotational acceleration [rad / s ² ] around the X axis, Y axis, and Z axis. . Similarly, the position of the column structure CL in the X direction, the Y direction, and the Z direction and the rotation angles around the X axis, the Y axis, and the Z axis are measured by the pair of position sensors (not shown). The Based on these measured values, the air dampers and the electromagnetic dampers in the plurality of vibration isolation tables 35 are configured so that the vibration of the column structure CL is kept small, the inclination angle of the column structure CL, and the height in the Z direction. Acts to maintain a constant value.

  Further, on the region surrounded by the plurality of support members 34 on the base plate 33 on the pedestal 32 and the active vibration isolation table 35, the wafer base WB is interposed via three or four active vibration isolation tables 41. Is supported. On wafer base WB, wafer stage WST holding wafer W is movably mounted. The anti-vibration table 41 includes an air damper and an electromagnetic damper similarly to the anti-vibration table 35, and the anti-vibration table 41 supports the wafer stage WST on the upper surface (installation surface) of the pedestal 32. The anti-vibration table 41 actively suppresses vibrations of the wafer base WB and the wafer stage WST based on measurement information from an acceleration sensor and a position sensor (not shown) on the wafer base WB.

  The anti-vibration tables 35 and 41 of this example and their control systems (described later) each constitute an anti-vibration device. The systems including the vibration isolation tables 35 and 41 and their control systems can also be called AVIS (Active Vibration Isolation System), which is an active vibration isolation system. The anti-vibration table 35 supports the reticle stage RST and the projection optical system PL via the column structure CL, and the scanning speed of the reticle stage RST during scanning exposure is higher than the scanning speed of the wafer stage WST. The reciprocal times (for example, 4 times) the projection magnification β is faster. On the other hand, since the anti-vibration table 41 supports only the wafer stage WST via the wafer base WB, the column structure CL is more susceptible to vibration than the wafer base WB. Therefore, the vibration isolation performance of the vibration isolation table 35 can be set higher than the vibration isolation performance of the vibration isolation table 41. In this case, as an example, in the anti-vibration table 41, the air damper may only control the pressure so that the position of the wafer base WB in the Z direction becomes substantially constant, for example.

  As described above, the active vibration isolation tables 35 and 41 of FIG. 2 can be configured in substantially the same manner. Below, the structure of the vibration isolator 35 and its control system, and its operation will be described as a representative example. Hereinafter, a mechanism for suppressing vibration in the Z direction, which is a direction parallel to the optical axis AX of the projection optical system PL, will be described. This is a mechanism for suppressing vibration in the X direction and the Y direction, and further the X axis. It can be similarly applied to a mechanism that suppresses vibration in the rotational direction around the Y axis and the Z axis.

  FIG. 3 shows one vibration isolator 35 in FIG. 2 and its control system. In FIG. 3, a support member 34 is installed on a base plate 33 on the pedestal 32, and the first column 36 is placed on the support member 34 via a bottom plate 42, an air damper 43, and an upper plate 44. The air damper 43 as a gas damper is obtained by enclosing air as a gas in a flexible hollow bag in a state in which the pressure can be controlled. That is, for example, a regulator 61 is connected to an air intake 45 that is an end of a utility pipe (not shown) connected to a compressor (not shown) as a common compressed air source in a factory via a pipe 46A. The air damper 43 is connected to the pipe 61B having flexibility by attaching a servo valve 47 capable of controlling the air flow rate to the air pipe 61. Further, a pressure sensor 62 for measuring information on the internal pressure (supply pressure SP) and a flow rate sensor 63 for measuring information on the flow rate of air passing through the inside are mounted on the pipe 46A. The measurement values of the pressure sensor 62 and the flow sensor 63 are supplied to the vibration isolator control system 48. However, in this example, the measured value of the flow sensor 63 is used only for monitoring the flow rate.

  The supply pressure SP, which is the air pressure supplied from the air intake 45 in this example to the pipe 46A, has an average value of about 700 kPa (approximately 7 atm) as shown in FIG. 6 and about 300 kPa with a period of several tens of seconds. The width fluctuates greatly in a sawtooth shape, and a pulsed pressure fluctuation (see FIG. 7) is also superimposed due to other usage conditions in the factory. In FIG. 6, the horizontal axis represents time (s) and the supply pressure SP on the vertical axis represents the deviation (measured value of the pressure sensor) from the average value of pressure in voltage (V). On the other hand, the regulator 61 in FIG. 3 has a function of smoothing and outputting pressure fluctuation (original pressure fluctuation) of the supplied gas, and smoothing that is air pressure supplied from the regulator 61 into the pipe 46B. As shown in FIG. 6, the pressure RP is considerably stabilized in the vicinity of approximately 320 kPa (approximately 3 atmospheres) as compared with the supply pressure SP. The smoothing pressure RP on the vertical axis in FIG. 6 represents pressure in voltage (V). However, when the supply pressure SP has a polygonal line or pulse-like pressure fluctuation, the influence cannot be completely removed by the regulator 61, so that a certain degree of fluctuation also appears in the smoothing pressure RP.

Returning to FIG. 3, a pressure sensor 28 for measuring information of the internal pressure of the air damper 43 is provided on the side surface of the air damper 43, and the measurement value of the pressure sensor 28 is supplied to the vibration isolation table control system 48. As the pressure sensors 28 and 62, a sensor in which a strain gauge is fixed to a diaphragm, a sensor using deformation of a silicon substrate, or the like can be used.
A voice coil motor 50 as an electromagnetic damper is installed between the support member 34 and the first column 36 in parallel with the air damper 43. The voice coil motor 50 includes a stator 50b fixed to the upper surface of the support member 34 and permanent magnets arranged at a predetermined pitch in the Z direction, and a mover 50a fixed to the bottom surface of the first column 36 and mounted with a coil. It consists of and. Further, the acceleration sensor 40 and the position sensor 49 are fixed to the first column 36. In the example of FIG. 3, the acceleration sensor 40 measures acceleration information in the Z direction of the first column 36, and the position sensor 49 supports the support member 34. The relative position in the Z direction of the first column 36 relative to (or the floor surface), or information on the relative displacement in the Z direction is measured. As an example, the acceleration sensor 40 is a piezoelectric acceleration sensor, and the position sensor 49 is an eddy current displacement sensor. A speed sensor may be used as a sensor for detecting acceleration information. In this case, the speed information detected by the speed sensor may be differentiated once to obtain acceleration information.

  The acceleration sensor 40 in FIG. 3 represents one sensor for measuring the acceleration of the first column 36 at a position where the air damper 43 and the voice coil motor 50 are installed. The measurement values (signals corresponding to the acceleration and position) of the acceleration sensor 40 and the position sensor 49 are supplied to the anti-vibration table control system 48. The anti-vibration table control system 48 controls the flow rate of the air passing through the servo valve 47 based on the measurement values of the position sensor 49, the pressure sensors 28 and 62, and the acceleration sensor 40. The internal pressure of the air damper 43 is controlled so that the position in the Z direction becomes a predetermined target position. The sampling rate of the position sensor 49, the pressure sensors 28 and 62, and the acceleration sensor 40 is set to be several times or more the upper limit (about several tens Hz in this example) of the response frequency of the internal pressure of the air damper 43.

In parallel with this, the anti-vibration table control system 48 controls the current flowing through the coil of the mover 50a of the voice coil motor 50 based on the measurement values of the acceleration sensor 40 and the position sensor 49. The thrust in the Z direction by the voice coil motor 50 is controlled so that the position in the Z direction becomes a predetermined target position.
Next, a control system for controlling the internal pressure of the air damper 43 in the vibration isolator control system 48 of FIG. 3 will be described. FIG. 4 is a dynamic model of the air damper 43 in the vibration isolator 35 of FIG. In FIG. 4, the installation surface 15 corresponds to the surface of the pedestal 32 of FIG. 3, and the structure 16 corresponds to the first column 36 of FIG. More precisely, the structure 16 includes the first column 36, the reticle base 37, the reticle stage RST, the second column 38, the illumination system subchamber 39, the illumination optical system 9, the projection optical system PL, and the like shown in FIG. include. The mass of the portion supported by the air damper 43 in the structure 16 is M, the viscosity proportionality coefficient of the air damper 43 is D, and the spring constant is K. At this time, the mass M is a coefficient of resistance (inertia) according to the acceleration of the structure 16, the viscosity proportional coefficient D is a coefficient of resistance according to the speed of the structure 16, and the spring constant K is the structure. It can be regarded as a coefficient of resistance according to the position of 16. If the position of the installation surface 15 in the Z direction is x _{0 and} the position of the structure 16 in the Z direction is x, in this example, the relative position (x−x ₀ ) of the structure 16 with respect to the installation surface 15 is an example. The anti-vibration table 35 in FIG. 3 is controlled so that the predetermined target position x _p is reached. The relative position (x−x ₀ ) is measured as position information of the structure 16 (first column 36) by the position sensor 49 in FIG.

  FIG. 5 shows a configuration of a vibration isolator control system 48 for controlling the internal pressure of the air damper 43 shown in FIG. In FIG. 5, the vibration isolator 35 is represented by a block diagram as an equivalent circuit of the dynamic model of FIG. 4, and a virtual flow / pressure conversion unit 43 a that determines the internal pressure of the air damper 43 is also represented by a block diagram. It is represented. The variable s is a variable for Laplace transform. When the frequency is f (Hz), s = i2πf in a steady state. The anti-vibration table control system 48 can basically be configured by any of computer software, digital circuit, or analog circuit.

In FIG. 5, the internal pressure of the air damper 43 in the vibration isolator 35 is determined according to the flow rate controlled by the servo valve 47 whose flow rate gain is G _q (m ³ / (s · V)). Set by The input signal w (V) to the servo valve 47 is generated by a control unit 76 that basically includes an amplifier 52, an acceleration PI compensator 54, and a pressure PI compensator 56. The control unit 76 further includes a position feedback unit that feeds back the detection result of the position sensor 49, an acceleration feedback unit that feeds back the detection result of the acceleration sensor 40, and a pressure feedback unit that feeds back the detection result of the pressure sensor 28. ing.

In this case, the block B12 the input side of the position sensor 49, the relative position (x-x ₀₎ by subtracting the position x ₀ of the Z direction of the surface on the position x of the Z-direction of the structure 16 and (= [Delta] x ) Shows a hypothetical calculation. When the position sensor 49 is an eddy current displacement sensor, a signal corresponding to the relative position Δx measured by the position sensor 49 is subtracted as a voltage signal vs via the amplifier 58 having a gain k _pos (V / m). This is fed back to the device 51. The amplifier 58 and the subtractor 51 constitute a position feedback unit.

A signal v _pos (usually a constant voltage (V)) corresponding to the target position x _p in the Z direction of the structure 16 is input to the subtractor 51 from a target position setting unit (not shown). The signal corresponding to the difference signal (v _pos −vs) is supplied to the subtractor 53 as the signal a 1 (target value of acceleration of the structure 16) through the amplifier 52 having the gain k _s .
A signal corresponding to the acceleration of the structure 16 measured by the acceleration sensor 40 is fed back to the subtractor 53 as a signal a2 through an amplifier 59 having a gain k _acc (V / (m / s ² )). . The amplifier 59 and the subtractor 53 constitute an acceleration feedback unit.

Then, the subtractor 53 supplies the difference (a1-a2) between the two signals to the acceleration PI compensator 54 as a signal a3 corresponding to the acceleration control error of the structure 16. The acceleration PI compensator 54 subtracts the signal b1 obtained by multiplying the input signal a3 by the transfer function k _ar (1 + sT _a ) / (sT _a ) using the gain k _ar and the time constant T _a (s). 55.
Also, the information of the internal pressure p (Pa) of the air damper 43 is measured by the pressure sensor 28, and the measurement signal is fed back to the subtractor 55 as the signal b2 through the amplifier 60 having the gain _kg (V / Pa). ing. The amplifier 60 and the subtractor 55 constitute a pressure feedback unit. The subtractor 55 supplies the difference (b1-b2) between the two signals to the pressure PI compensator 56 as a signal b3 corresponding to the control error of the internal pressure of the air damper 43. The pressure PI compensator 56 adds a signal w ′ obtained by multiplying the input signal b3 by the transfer function k _pr (1 + sT _p ) / (sT _p ) using the gain k _pr and the time constant T _p (s). Input to the instrument 57.

In a state where the disturbance is ignored, the adder 57 supplies the signal w ′ to the servo valve 47 having a flow rate gain G _q ((m ³ / s) / V) as a signal w for controlling the flow rate. As a result, the flow rate of the air supplied from the servo valve 47 to the air damper 43 is set to w · G _q . If the servo valve 47 is controlled by voltage, the signals w ′ and w are generated as voltage.
Further, in FIG. 5, the compression rate of the air damper 43 (flow rate / pressure conversion unit 43a) is β ₀ (1 / Pa), the capacity is V ₀ (m ³ ), and the flow conductance is c ((m ³ / s) / Pa. ), The time constant T _p of the pressure PI compensator 56 is set to be T _p = β ₀ V ₀ / c, and the time constant T _a of the acceleration PI compensator 54 is, for example, T _a = T _p / ( G _q k _pr k _g ). As a result, the internal pressure p of the air damper 43 in the vibration isolator 35 is controlled to a target value (a value corresponding to the signal b1 output from the acceleration PI compensator 54). As a result, the acceleration of the structure 16 is controlled to a target value (a value corresponding to the signal a1 output from the amplifier 52), and finally the signal vs corresponding to the relative position Δx of the structure 16 becomes the target position _xp . Control is performed so that the corresponding signal v _pos is obtained.

5 includes a position feedback unit, an acceleration feedback unit, and a pressure feedback unit in order to set the relative position Δx of the structure 16 as a target position. For example, the internal pressure of the air damper 43 is set to a predetermined target. If it is only necessary to control the value, the position feedback unit and the acceleration feedback unit can be omitted.
In FIG. 5, the flow rate feedback unit 75 is virtually formed by the mechanism of the servo valve 47 and the vibration isolation table 35. The flow rate feedback unit 75 subtracts the speed obtained by differentiating the position of the installation surface from the speed of the block B13 from the speed obtained by virtually integrating the acceleration of the structure 16, and the output of the block B14. a block B15 multiplying the effective pressure receiving area a ₀ of the air damper 43, and a virtual subtraction of the flow rate / pressure conversion section 43a. That is, since the output of the block B15 corresponds to the increasing speed of the volume of the air damper 43, the pressure of the air damper 43 is determined based on the flow rate obtained by subtracting the increasing speed of the volume of the air damper 43 from the flow rate of the servo valve 47. Is done.

Further, in this example, in FIG. 3, a circuit for compensating for the influence of the pressure fluctuation in the air damper 43 due to the fluctuation of the air pressure supplied from the air intake portion 45 (original pressure fluctuation) is provided. Therefore, in FIG. 5, the fluctuation d _pr (Pa) of the supply pressure SP from the air intake 45 measured by the pressure sensor 62 flows through the virtual disturbance part 64 of the transfer function G _d (s). It is assumed that the fluctuation d _fl (m ³ / s) is added to the output of the servo valve 47.

Then, the following expressions (1) to (1) are applied to the air pressure fluctuation d _pr so that the influence of the flow rate fluctuation d _fl does not affect the relative position (x−x ₀ ), that is, the output vs of the position sensor 49. (4) transfer function G _ff1 represented by _{(s), G ff2 (s} ), G ff3 (s) and G _FF4 (s) feedforward compensator with (hereinafter, referred to as FF compensator) 66, 67, A feedforward unit 65 comprising 68 and 69 is provided.

この場合、ＦＦ補償器６６，６７，６８及び６９の出力（以下、ＦＦ信号ともいう）は、それぞれ減算器５１（目標位置ｖ_pos）、減算器５３（加速度ＰＩ補償器５４の前段）、減算器５５（圧力ＰＩ補償器５６の前段）、及び加算器５７（圧力ＰＩ補償器５６の後段）に加算信号として供給される。なお、実際には、４つのＦＦ補償器６６〜６９のうちの１つのみが設けられる。つまり、ＦＦ信号の加算点から外乱入力点直前までの直達の伝達関数の逆関数と、外乱の伝達関数Ｇ_d（ｓ）とを掛けたものをＦＦ補償器６６〜６９の伝達関数とすればよい。

In this case, the outputs of the FF compensators 66, 67, 68, and 69 (hereinafter also referred to as FF signals) are a subtracter 51 (target position v _pos ), a subtractor 53 (previous stage of the acceleration PI compensator 54), and a subtractor, respectively. Is supplied as an addition signal to the device 55 (the front stage of the pressure PI compensator 56) and the adder 57 (the rear stage of the pressure PI compensator 56). Actually, only one of the four FF compensators 66 to 69 is provided. That is, if the inverse transfer function of the direct transfer function from the addition point of the FF signal to just before the disturbance input point is multiplied by the transfer function G _d (s) of the disturbance, the transfer function of the FF compensators 66 to 69 is used. Good.

Here, the time constant T (s) and the coefficient k (m ³ / (Pa · s)), the transfer function G _d (s) of the disturbance is set as follows.
G _d (s) = k · Ts / (1 + Ts) (5)
As an example, assuming that the FF compensator 67 is used in the feedforward unit 65, the transfer function G _ff2 (s) of Expression (2) is rewritten using Expression (5), and the following expression is obtained.

この式において、時定数Ｔ_a及びＴ_pにはフィードバック系の値をそのまま代入する。調整パラメータは時定数ＴとＦＦゲインｋ_ffの２個となる。後者は式（２）と式（５）より、ｋ_ff＝ｋ／（Ｇ_qｋ_prｋ_ar）であるが、個々のパラメータを同定する必要はなく、一括のゲインｋ_ffとおいて、時定数ＴもＦＦ制御の効果を観察して実験的に定めればよい。

In this equation, the values of the feedback system are substituted as they are for the time constants T _a and T _p . There are two adjustment parameters, a time constant T and an FF gain _kff . The latter equation (2) from equation (5), is a _{k ff = k / (G q} k pr k ar), there is no need to identify the individual parameters, at a gain k _ff batch, the time constant T may be determined experimentally by observing the effect of FF control.

When a reciprocating compressor is used as the air intake unit 45 of FIG. 5 and the FF compensator 67 having the transfer function G _ff2 (s) of Expression (6) is mounted, and when the FF compensators 66 to 69 are not mounted at all. FIG. 7 shows the experimental results when a transient pressure disturbance occurs in addition to the periodic source pressure fluctuation.
In FIG. 7, the horizontal axis represents time t (s), the vertical supply pressure SP represents the pressure deviating from the average value in voltage (V), and the vertical axis relative position Δx (= xx). ₀ ) represents the position in terms of voltage (V). Curves E1 to E4 show a case where the FF compensators 66 to 69 are not implemented at all, and curves F1 to F4 show a case where the FF compensator 67 having the transfer function G _ff2 (s) of Expression (6) is implemented. Is shown.

  In FIG. 7, the supply pressure SP indicated by the curves E1 and F1 has a polygonal pressure change in the regions E1a and F1a, respectively, and has a pulsed pressure change in the regions E1b and F1b. Corresponding to this, the relative position Δx indicated by the curve E2 in which the FF compensators 66 to 69 are not mounted has a position variation in the regions E2a and E2b. However, in the relative position Δx indicated by the curve F2 on which the FF compensator 67 is mounted, the position fluctuations of the regions F2a and F2b are small.

  Further, the supply pressure SP indicated by the curves E3 and F3 has a random pressure drop in the regions E3b and F3b, respectively. Correspondingly, the relative position Δx indicated by the curve E4 in which the FF compensators 66 to 69 are not mounted has a position variation in the region E4b. However, the relative position Δx indicated by the curve F4 on which the FF compensator 67 is mounted has a small position fluctuation in the region F4b.

The effect of the vibration isolator of this embodiment is as follows.
(1) As shown in FIGS. 3 and 5, a vibration isolator having an air intake 45 for supplying air and an air damper 43 for supplying the air to support the first column 36 on the base plate 33. In the anti-vibration device including the anti-vibration unit 35 and the anti-vibration table control system 48, the flow rate of the air supplied from the air intake 45 is controlled and the position information of the servo valve 47 supplied to the air damper 43 and the first column 36 is measured. A position sensor 49, a pressure sensor 62 for measuring information on the pressure of air supplied from the air intake 45 (air state), and an air damper via a servo valve 47 based on the position information measured by the position sensor 49. 43 is supplied from the air intake unit 45 based on pressure information measured by the control unit 76 (first control unit) that controls the pressure of the air in the air pressure sensor 62 and the pressure sensor 62. And a feedforward section 65 that gives a thrust to the first column 36 relative to the base plate 33 so as to suppress the position variation of the first column 36 caused by a change in the pressure of the air (second control unit).

Therefore, when a pressure fluctuation of the air supplied from the air intake portion 45 occurs, thrust is applied so as to suppress a position fluctuation caused by the fluctuation. As a result, in the active vibration isolator 35 using the air damper 43, the vibration isolation performance when the pressure fluctuation of the air supplied from the air intake 45 is large can be improved.
(2) Further, a regulator 61 for smoothing the pressure of the air supplied from the air intake 45 is provided, and the servo valve 47 controls the flow rate of the air supplied from the regulator 61 and supplies it to the air damper 43. Therefore, even if the pressure of the air supplied from the air intake 45 greatly fluctuates at a relatively long period, the pressure of the air in the air damper 43 can be easily maintained within the target range.

(3) The feedforward unit 65 controls the flow rate of air in the servo valve 47 so as to cancel the flow rate variation d _fl of the servo valve 47 due to the variation d _pr of the supply pressure SP from the air intake unit 45. Yes. Therefore, the flow rate fluctuation d _fl due to the fluctuation d _pr of the supply pressure SP can be compensated with high accuracy, and the stability of the position of the first column 36 is improved.
(4) Moreover, the pressure sensor 28 which measures the pressure information of the air in the air damper 43 is provided, and the control part 76 is based on the information measured by the pressure sensor 28 and the position sensor 49, and the air damper 43 via the servo valve 47. The air pressure inside is controlled. Therefore, the control accuracy of the air pressure in the air damper 43 is improved.

[Second Embodiment]
Next, a second embodiment of the present invention will be described with reference to FIGS. In this embodiment, the vibration control table 35 of FIG. 3 is used and the control system substantially the same as the vibration control table control system 48 of FIG. 5 is used, but instead of feeding forward the measurement value of the gas sensor 62 of FIG. The measured value of the flow sensor 63 is fed forward to suppress the relative displacement Δx caused by the air flow fluctuation (original flow fluctuation) of the air intake 45.

FIG. 8 shows a main part of the control system of the present example in which parts corresponding to those in FIG. In FIG. 8, the flow rate sensor 63 measures the fluctuation d _flo of the flow rate of the air supplied from the air intake 45 in FIG. 3. In this case, a flow rate variation d _fl obtained by multiplying the variation d _flo by the reduction rate k _fl in the virtual disturbance unit 70 is added to the output side of the servo valve 47.

Therefore, in this example, in order to cancel out the flow rate fluctuation d _fl , as an example, the fluctuation d _flo is _passed through the FF compensator 71 having a transfer function G _ff5 (s) of the following equation, and the subtractor 53 (acceleration PI compensator 54). Is supplied as an FF signal. Here, it is assumed that there is no time delay in measuring the fluctuation d _flo .

式（７）の実装にあたっては、時定数Ｔ_a及びＴ_pのいずれかを調整パラメータとして、他方をフィードバック系（制御部７６）での値をそのまま使用する。また、式（７）の右辺第１項のｋ_fl／（Ｇ_qｋ_prｋ_ar）を一括してＦＦゲインｋ_ff(fl)として調整すればよい。

In implementing the expression (7), one of the time constants T _a and T _p is used as an adjustment parameter, and the other is used as it is as the value in the feedback system (control unit 76). Further, k _fl / (G _q k _pr k _ar ) in the first term on the right side of the equation (7) may be adjusted as a FF gain k _{ff (fl)} at once.

Specifically, in the control system of FIG. 8 shows the state of vibration when adjusted for a constant T _a time FF gain k _ff and _(fl) of the formula (7) as an adjustment parameter to FIG.
In FIG. 9, the horizontal axis represents time t (s), the supply pressure SP (kPa) on the vertical axis is represented by a curve F5, and the flow rate SF (L / min) measured by the flow sensor 63 of FIG. It is represented by F6. In this case, the relative position Δx (represented by voltage (V)) when the FF compensator 71 of FIG. 8 is not provided is the curve E5 of FIG. 9, and the FF compensator 71 of FIG. and the time constant T _a the 10s, FF gain k _ff relative position Δx in the case of _(fl) was 0.13 is curved F7. From the curve F7, it can be seen that even if the measured value of the flow rate fluctuation of the air intake 45 by the flow rate sensor 63 is feedforward, the vibration of the vibration isolation table displacement is well suppressed.

Note that an FF compensator 71 having a transfer function G _ff5 ′ (s) of the following expression may be mounted instead of the transfer function G _ff5 (s) of Expression (7). In this case, the delay of the path through which the flow rate fluctuation d _fl is transmitted through the reduction rate k _fl is collectively replaced with the time constant T _{fl of the} primary delay.

この式（８）の伝達関数を用いる場合にも、除振台変位の揺動はよく抑制される。なお、本例の場合にも、図８のＦＦ補償器７１と同様に、図５の減算器５１，５５又は加算器５７にＦＦ信号（ただし、伝達関数は式（１）〜（４）と同様に変化する）を供給するＦＦ補償器を備えてもよい。

Even when the transfer function of this equation (8) is used, the vibration of the vibration isolation table displacement is well suppressed. Also in the case of this example, similarly to the FF compensator 71 of FIG. 8, the FF signal (however, the transfer function is expressed by the equations (1) to (4)) to the subtractors 51 and 55 or the adder 57 of FIG. There may also be provided an FF compensator that supplies the same).

[Third Embodiment]
A third embodiment of the present invention will be described with reference to FIG. Also in this embodiment, the vibration control table 35 of FIG. 3 is used and a control system substantially the same as the vibration control table control system 48 of FIG. 5 is used. However, in this example, instead of controlling the flow rate of air in the servo valve 47 so as to cancel out the flow rate variation d _fl of the servo valve 47 due to the variation d _pr of the supply pressure SP from the air intake 45, FIG. The thrust of the voice coil motor 50 is controlled.

FIG. 10 shows a main part of the vibration isolator control system 48A of this example in which the same reference numerals are assigned to the parts corresponding to FIG. In FIG. 10, the fluctuation d _pr of the supply pressure SP measured by the pressure sensor 62 from the air intake 45 is a factor of the flow fluctuation d _fl of the servo valve 47 via the transfer function G _d (s). . In this example, the pressure fluctuation d _pr is supplied to the subtraction side of the subtractor 73 as the FF signal via the FF compensator 72 of the transfer function G _ff6 (s). A drive signal b3v of the voice coil motor 50 generated based on the acceleration sensor 40 and the position sensor 49 in FIG. 3 is supplied to the addition side of the subtractor 73, and a signal obtained by subtracting the FF signal from the drive signal b3v. Is supplied to the voice coil motor 50 via a driver 74 having a gain G _VCO .

In this case, the transfer function G _ff6 (s) of the FF compensator 72 is set so that the flow rate fluctuation d _fl of the servo valve 47 does not affect the relative position Δx (= x−x ₀ ). Thereby, even if a pressure fluctuation occurs in the air intake portion 45, the vibration of the vibration isolation table is well suppressed.
Further, in this example, instead of detecting the pressure fluctuation of the air intake section 45, the flow quantity fluctuation may be detected, and the feedforward control may be performed based on this result.

[Modification of Embodiment]
FIG. 11 shows a vibration isolator control system 48B according to a modification of the embodiment of FIG. In FIG. 11 where the same or similar reference numerals are given to the parts corresponding to FIG. 5, the fluctuation d _pr of the supply pressure SP measured by the pressure sensor 62 is added by the control unit 76 via the FF compensator 69A and the switch unit 81. It is supplied to the device 57.

The FF compensator 69A has substantially the same transfer function G _ff4 (s) as the FF compensator 69 of FIG. However, the FF compensator 69A has a low-pass filter 69a (time constant T) to which a fluctuation d _pr (for example, a voltage signal) is supplied and a first compensator 69c of the transfer function G1 (s) in order to easily adjust the gain. And a second compensator 69b of the transfer function G2 (s) to which the output of the low-pass filter 69a is supplied, and a subtractor 69d that subtracts the output of the second compensator 69b from the output of the first compensator 69c. The transfer function G1 (s) is the same as equation (4), and the transfer function G2 (s) is obtained by adding a variable value α to equation (4).

  Further, the switch unit 81 includes, for example, a terminal 81a to which a switching signal CS1 for switching on / off of the FF compensator 69A is supplied from the main control system 20 in FIG. 1, and a low-pass filter to which the switching signal CS1 is supplied from the terminal 81a. 81b (or an integrator), and a multiplier 81c that multiplies the output of the subtractor 69d by the output of the low-pass filter 81b and supplies the result to the adder 57. As shown in FIGS. 14A and 14B, the switching signal CS1 becomes high level (predetermined unit level) during the period (ON period) in which the FF compensator 69A is used, and does not use the FF compensator 69A. It is a signal that becomes low level (almost 0) in the period (off period). 14A and 14B, the horizontal axis is time t (s). In the vertical axis, SP (kPa) is the supply pressure in the air intake 45, and Δx (μm) is measured by the position sensor 49. This is the relative position of the first column 36.

  In FIG. 11, when adjusting the FF compensator 69A, for example, the relative position Δx measured by the position sensor 49 is monitored in a state where the switching signal CS1 is set to a high level, and the relative position Δx is within a predetermined range. What is necessary is just to adjust the gain of the 2nd compensator 69b so that it may be settled. As a result, the transfer function of the FF compensator 69A can be easily optimized in accordance with the actual vibration isolator 35.

  In the switch unit 81, the low-frequency component (delayed component) CS2 that has passed through the low-pass filter 81b in the input switching signal CS1 is supplied to the multiplier 81c. Therefore, even when the switching signal CS1 changes between the high level and the low level at high speed, the FF signal from the FF compensator 69A gradually changes from the multiplier 81c to the adder 57 of the control unit 76. Supplied in. Therefore, it is possible to reduce hunting (variation) of the relative position Δx when the on / off of the FF compensator 69A is controlled by the switching signal CS1.

  As an example, as shown in FIGS. 14A and 14B, in the vibration isolator control system 48B of FIG. 11, when the FF compensator 69A is switched from off to on by the switching signal CS1, and from on to off. When switched, the relative position Δs hunting is relatively small as shown by the curves C2A and C2B, respectively. On the other hand, in the vibration isolator control system 48B of FIG. 11, when the low pass filter 81b is removed from the switch unit 81, the switching is performed as shown by the curves C3A and C3B of FIGS. A large hunting occurs at the relative position Δx.

Even when the FF signals I2 to I4 are supplied to any of the subtractors 51, 53, and 55 in FIG. 11, the same hunting as that of the switch unit 81 is provided between the FF signals I2 to I4 and the corresponding FF compensator. It is preferable to provide a switch part for reduction.
Also, as shown in FIG. 12, the same switch unit 81 as in FIG. 11 may be arranged between the FF compensator 71 and the subtractor 53 in the embodiment of FIG. Also in this modification, hunting of relative displacement when the FF compensator 71 is switched on / off can be reduced.

Next, FIG. 13 shows a vibration isolator control system 48C of another modification of the embodiment of FIG. In FIG. 13, in which parts corresponding to those in FIG. 5 are assigned the same reference numerals, the fluctuation d _pr of the supply pressure SP measured by the pressure sensor 62 is controlled by the control unit via the FF compensator 69, the difference circuit 82, and the switch unit 83. 76 pressure PI compensators 56.
The pressure PI compensator 56 includes an adder 56a to which the signal b3 from the subtractor 55 is supplied, an amplifier 56c with a gain k _p , and an integrator 56b with a transfer function k _i / s that integrates the signal from the adder 56a. And an adder 56d that adds the output of the amplifier 56c and the output of the integrator 56b and supplies the sum to the servo valve 47. The difference circuit 82 includes a delay circuit 82a and a subtractor 82b to which the signal b4 from the FF compensator 69 is supplied. The delay circuit 82a outputs a signal obtained by delaying the signal b4 by a predetermined unit time, and the subtractor 82b outputs a signal b5 obtained by subtracting the output of the delay circuit 82a from the signal b4.

Further, the switch unit 83 switches, for example, from the main control system 20 of FIG. 1 to a terminal 83a to which a switching signal CS1 for switching on / off of the FF compensator 69 is supplied and a signal b5 supplied from the difference circuit 82. A multiplier 83b for supplying a signal obtained by multiplying CS1 to the adder 56a of the pressure PI compensator 56; In the period in which the switching signal CS1 is at a high level, the pressure PI compensator 56 adds the signal b5 output from the difference circuit 83 by the integrator 56b to the signal w that is finally output. As a result, the influence of the flow rate fluctuation d _fl from the disturbance part 64 is offset. Note that the signal w (voltage (V)) shown in FIGS. 14A and 14B is a signal obtained by integrating the output signal of the difference circuit 83 in FIG. 13 by the integrator 56b.

  In the modification of FIG. 13, the differential signal output from the FF compensator 69 is an FF signal. When the FF compensator 69 is switched on / off by the switching signal CS1, the fluctuation component of the signal output from the FF compensator 69 is supplied from the multiplier 83b to the adder 55a of the control unit 76. Therefore, hunting of the relative position Δx when controlling the on / off of the FF compensator 69 can be reduced.

As an example, as shown in FIGS. 14A and 14B, in the vibration isolator control system 48C of FIG. 13, when the FF compensator 69 is switched from OFF to ON by the switching signal CS1, and from ON to OFF. In the case of switching, the hunting of the relative position Δs is the smallest as shown by the curves C1A and C1B, respectively.
In FIG. 13, the difference circuit 82 may be disposed at a position I1 preceding the FF compensator 69. In this case, the switch unit 83 is disposed between the FF compensator 69 and the control unit 76.

  In the above embodiment and its modifications, air is used as the gas for the gas damper. Instead, nitrogen gas or a rare gas (such as helium or neon) or a mixed gas of these gases is used. May be.

  The present invention can also be applied to a case where vibration isolation is actively performed with an immersion type exposure apparatus disclosed in, for example, International Publication No. 99/49504 pamphlet. 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.

It is a figure which shows schematic structure of the projection exposure apparatus of 1st Embodiment. FIG. 2 is a partially cutaway view showing a state where the projection exposure apparatus of FIG. 1 is installed on the floor. It is a figure which shows the one anti-vibration stand 35 in FIG. 2, and its control system. It is a figure which shows the dynamic model of the vibration isolator 35 of FIG. It is a block diagram which shows the structure of the vibration isolator control system 48 of 1st Embodiment. It is a figure which shows an example of supply pressure SP by the air intake part 45 of FIG. 3, and smoothing pressure RP by the regulator 61. FIG. In 1st Embodiment, it is a figure which shows the relationship between supply pressure SP and relative position (DELTA) x, dividing into the case where feedforward control is performed, and the case where it is not performed. It is a block diagram which shows the structure of the principal part of the vibration isolator control system of 2nd Embodiment. In 2nd Embodiment, it is a figure which shows the relationship between supply flow rate SF and relative position (DELTA) x, dividing into the case where feedforward control is performed, and the case where it is not performed. It is a block diagram which shows the structure of the vibration isolator control system of 3rd Embodiment. It is a block diagram which shows the modification of embodiment of FIG. It is a block diagram which shows the modification of embodiment of FIG. It is a block diagram which shows another modification of embodiment of FIG. It is a figure where it uses for operation | movement description of the modification shown in FIG.11 and FIG.13.

Explanation of symbols

  28 ... Pressure sensor, 33 ... Base plate, 35 ... Anti-vibration table, 36 ... First column, 40 ... Acceleration sensor, 43 ... Air damper, 45 ... Air intake, 47 ... Servo valve, 48 ... Anti-vibration table control system, 49 ... Position sensor, 50 ... Voice coil motor, 62 ... Pressure sensor, 63 ... Flow rate sensor, 65 ... Feed forward unit, 66-69 ... FF compensator, 71 ... FF compensator, 76 ... Control unit

Claims (11)

In a vibration isolator having a gas supply source for supplying gas, and a gas damper for supporting the structure on the installation surface by supplying the gas inside,
A flow rate control unit for controlling the flow rate of gas supplied from the gas supply source and supplying the gas damper;
A position information sensor for measuring position information of the structure;
A gas state sensor for measuring the state of the gas supplied from the gas supply source;
A first control unit for controlling the pressure of the gas in the gas damper via the flow rate control unit based on position information measured by the position information sensor;
Based on the gas state measured by the gas state sensor, thrust is applied to the structure with respect to the installation surface so as to suppress the position fluctuation of the structure due to the state fluctuation of the gas supplied from the gas supply source. And a second control unit that provides the vibration isolator. A gas smoothing unit that smoothes the pressure of the gas supplied from the gas supply source;
The vibration isolator according to claim 1, wherein the flow rate control unit controls the flow rate of the gas supplied from the gas smoothing unit and supplies the gas damper to the flow rate control unit. A low-pass filter unit to which a switching signal for controlling on / off of the second control unit is supplied;
The vibration isolator according to claim 1 or 2, further comprising a multiplication unit that multiplies the output of the low-pass filter unit by a control signal corresponding to the thrust by the second control unit.   The vibration isolation device according to claim 1, wherein the second control unit includes a fluctuation amount calculation unit that obtains a fluctuation amount of a gas state measured by the gas state sensor. The first control unit includes an integration unit that integrates difference information between the position information and target position information,
The anti-vibration device according to claim 4, wherein an output of the second control unit is added to an input of the integration unit.   6. The multiplier according to claim 4, further comprising a multiplier that multiplies a switching signal for controlling on / off of the second controller by a control signal corresponding to the thrust by the second controller. The vibration isolator as described.   The vibration isolator according to any one of claims 1 to 6, wherein the second control unit controls a flow rate of the gas in the flow rate control unit. An electromagnetic actuator that applies thrust to the structure with respect to the installation surface;
The vibration isolator according to any one of claims 1 to 6, wherein the second control unit controls a thrust force applied to the structure by the electromagnetic actuator.   The vibration isolator according to any one of claims 1 to 8, wherein the gas state sensor is a pressure sensor that measures pressure information of the gas.   The vibration isolator according to any one of claims 1 to 8, wherein the gas state sensor is a flow sensor that measures flow information of the gas. A pressure sensor for measuring pressure information of the gas in the gas damper;
The said 1st control part controls the pressure of the gas in the said gas damper via the said flow volume control part based on the information measured by the said pressure sensor and the said positional information sensor. The vibration isolator according to any one of 10.

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