JP2005311165A - Active mount and exposure apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an active mount and exposure apparatus with the vibration of the level block efficiently reduced, without dimensional enlargement. <P>SOLUTION: The active mount comprises a vibration-insulating support for supporting the level block, an actuator for driving the level block, a vibration sensor for sensing the rigid body vibration mode of the level block, a first vibration control loop for correcting the vibration sensor output and for causing the actuator to generate a driving force, and a vibration sensor for detecting the elastic vibration of the level block due to structural resonance (flexures, bends, twists, etc.). <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an exposure apparatus and an active mount for sequentially transferring and exposing a reticle pattern onto a wafer when a semiconductor element or a liquid crystal display element is manufactured in a lithography process.

  In a photolithography process for manufacturing a semiconductor element, an optical exposure apparatus that transfers a fine pattern of a reticle onto a silicon wafer coated with a photosensitive agent is used. The conventional exposure method is a step-and-repeat method in which an area of a wafer is sequentially moved into the exposure field of the projection optical system and the exposure of the reticle pattern is repeated. Recently, there is an increasing demand for a larger field of exposure due to the increase in the size of semiconductor elements. As a method for satisfying this demand, a reticle stage and wafer that hold a reticle by irradiating the reticle with slit-shaped illumination light. A step-and-scan type exposure apparatus that scans and exposes a pattern of the entire reticle onto a wafer while synchronously moving the wafer stage holding the lens at the reduction magnification ratio of the projection optical system is used.

  FIG. 3 shows an example of a step-and-scan exposure apparatus.

  The reticle 101 is held on a reticle stage 102 that can be driven in the X, Y, and θz (rotation around the Z axis) directions, and the wafer 103 is mounted on a wafer stage 104 that can be driven in the X, Y, and Z directions and the θx, θy, and θz directions. Is retained. The projection optical system 105, the laser interferometer 106 for measuring the stage position, and the focus sensor 107 for measuring the wafer image plane are all installed on the lens barrel surface plate 108. The lens barrel surface plate is an active mount at three or four points. 109 (shown only on the front two points in the figure), vibration isolation of the installation floor 110, and vibration suppression of the rigid body vibration mode (about 1 to 15Hz) of the surface plate. In other words, the active mount includes a support means 109a for supporting vibration isolation of the lens barrel surface plate, an actuator 109b for driving the lens barrel surface plate, a vibration sensor 111 for detecting a rigid body vibration mode of the lens barrel surface plate, and the vibration sensor. The vibration control loop (the filter circuit 112, the compensation circuit 113, and the drive circuit 114) that drives the actuator by compensating the output of the above.

The slit light emitted from the illumination system 115 is applied to the reticle 101 on which a fine pattern is formed, and the pattern is transferred onto the wafer 103 by driving the reticle stage 102 and the wafer stage 104. The driving direction of the reticle stage 102 and the wafer stage 104 during exposure is generally opposite, and the wafer stage 104 is mastered to maintain the speed ratio between the stages at 1/4 of the reduction magnification of the projection optical system 105. A master-slave synchronization control system having the reticle stage 102 as a slave is provided. In addition, a reaction force receiving structure 116 that is vibrationally insulated is provided for both the lens barrel base plate 108 and the installation floor 110, and the driving reaction acting on the stator of the first linear motor 117 when the stage is driven. A force equivalent to the force is applied to be canceled by the second linear motor 118 supported by the reaction force receiving structure to reduce the vibration remaining on the lens barrel surface plate.
JP 06-181158

  In an exposure apparatus, it is important to suppress vibrations on the lens barrel surface where a projection optical system that largely controls transfer quality and a laser interferometer that measures the stage position are arranged. Also in the apparatus, the structure of the lens barrel surface plate generated by the reaction force component that cannot be canceled due to the deviation of the force action lines of the first and second linear motors and the unevenness of the motor thrust, and the vibration transmission from the apparatus installation floor There has been a problem that the residual vibration due to resonance and structural resonance of a mounted device such as an illumination system deteriorates the transfer quality. In order to reduce this, the method of increasing the rigidity of the lens barrel surface plate and the mounted device to decrease the absolute value of deformation and vibration causes an increase in the surface plate weight and an increase in the size of the apparatus. In addition, the active mount built into the exposure system detects vibrations at low frequencies and controls vibrations, so it was unable to exert vibration damping effects on structural resonances on the lens barrel surface plate that exists in the high frequency band. .

  The present invention has been made to solve the above problems, and provides an active mount and an exposure apparatus that can effectively reduce vibration on a surface plate without increasing the size.

  Support means for supporting vibration isolation of the surface plate, an actuator for driving the surface plate, a vibration sensor for detecting the rigid body vibration mode of the surface plate, and compensating the output of the vibration sensor to generate a driving force for the actuator An active mount having a vibration control loop is provided with a vibration sensor for detecting elastic vibration due to structural resonance (bending, bending, twisting, etc.) of the surface plate. Furthermore, a vibration sensor for detecting elastic vibration due to structural resonance (bending, bending, twisting, etc.) of a structural member or device mounted on the surface plate is provided. A second vibration control loop that compensates for an output of a vibration sensor for detecting the elastic vibration and generates a driving force for the actuator is provided. In a preferred embodiment of the present invention, the vibration sensor for detecting the elastic vibration is an accelerometer or a speedometer, and the drive generated in the actuator is compensated for the output of the vibration sensor for detecting the elastic vibration. The force is a viscous force. Further, the exposure apparatus supports a surface plate on which a projection optical system and a measurement system are mounted by an active mount having the second vibration control loop.

(Function)
In the present invention, a vibration sensor for detecting elastic vibration due to structural resonance (flexion, bending, twisting, etc.) of the surface plate is further used, and structural resonance (flexure, bending, twisting) of a structural member or device mounted on the surface plate. Etc.) is provided to compensate for the output of the vibration sensor, and the driving force is applied to the actuator that drives the surface plate as a viscous force. As a result, damping of structural resonance on the surface plate is improved and vibration on the surface plate is reduced, so that the transfer accuracy of an exposure apparatus having a projection optical system and a measurement system mounted on the surface plate can be improved.

  As described above, in the active mount and exposure apparatus of the present invention, the vibration sensor for detecting elastic vibration due to the structural resonance (deflection, bending, twisting, etc.) of the surface plate supported by vibration isolation and the surface plate By providing a vibration sensor for detecting elastic vibration due to structural resonance (flexure, bending, torsion, etc.) of structural members and equipment mounted on the plate, and compensating the output of the vibration sensor, the viscous force is applied to the surface plate. Drive the actuator to act. This improves the damping of structural resonance on the surface plate on which the projection optical system and the measurement system are mounted, so that the transfer accuracy of the exposure apparatus can be improved without increasing the size of the surface plate.

  Examples of the present invention will be described below. FIG. 1 shows the arrangement of an exposure apparatus according to the first embodiment of the present invention.

  In the figure, the lens barrel surface plate 8 is supported at three points by an active mount 9 (only two points are shown). The active mount includes a support means 9a, an actuator 9b for driving the lens barrel base plate, a vibration sensor 11 for detecting a rigid body vibration mode of the lens barrel base plate, and an output of the vibration sensor to compensate the actuator. A vibration control loop (filter circuit 12, compensation circuit 13, drive circuit 14) for driving is provided.

  Furthermore, a vibration sensor 21 for detecting elastic vibration due to structural resonance (bending, bending, twisting, etc.) of the lens barrel surface plate, and a mounted object on the lens barrel surface plate such as the illumination system 15 and the reticle surface plate 22 Vibration sensors 23 and 24 for detecting vibrations due to structural resonance (bending, bending, twisting, etc.) are provided.

  A filter circuit 25 for extracting respective structural resonance structural resonance (bending, bending, twisting, etc.) components from the vibration sensor (21, 23, 24); a compensation circuit 27 for compensating for vibration from the filter circuit; The second vibration control loop is configured by the drive circuit 14 that generates a drive force for the actuator based on the signal of the compensation circuit. The vibration sensors (21, 23, 24) are accelerometers or speedometers, and can be arranged in any number of vibration parts on the surface plate, not limited to the lens barrel surface plate, illumination system, and reticle surface plate. The actuator may be a force generating actuator such as a linear motor, or a displacement generating actuator such as a piezoelectric element or a giant magnetostrictive element.

  The operation of the exposure apparatus configured as described above will be described.

  The slit light emitted from the illumination system 15 is applied to the reticle 1 on which a fine pattern is formed, and the pattern is transferred onto the wafer 3 by driving the reticle stage 2 and the wafer stage 4. The driving direction of the reticle stage and the wafer stage during exposure is opposite, and the master with the wafer stage as the master and the reticle stage as the slave to maintain the speed ratio at 1/4, which is the reduction magnification of the projection optical system 5. Slave-type synchronous control is performed.

  In addition, a reaction force receiving structure 16 that is vibrationally insulated is provided for both the lens barrel base plate 8 and the installation floor 10 so as to act on the stator of the first linear motor 17 when the stage is driven. The force equivalent to the force is applied to be canceled by the second linear motor 18 supported from the reaction force receiving structure to reduce the vibration remaining on the lens barrel surface plate.

  At this time, reaction force components that cannot be canceled due to deviations in the force action lines of the first and second linear motors and unevenness of the motor thrust, and structural resonance of the lens barrel surface plate that is generated by vibration transmission from the installation floor In addition, residual vibration occurs due to structural resonance of the mounted object such as the illumination system 15 and the reticle surface plate 22, but the vibration sensors 21, 23 and 24 and the filter circuit 25 cause structural resonance (flexion, bending, Elastic vibration due to torsion etc.) and vibration due to structural resonance (flexure, bending, torsion etc.) of the mounted object on the lens barrel surface plate are detected and extracted, and these signals are converted to speed by the compensation circuit 26, and the drive circuit A driving force is generated in the actuator 9 via 14. As a result, viscous force acts on the lens barrel surface plate, damping of structural resonance on the surface plate is improved, and vibration on the surface plate is reduced. Therefore, the exposure with the projection optical system and measurement system mounted on the surface plate. The transfer accuracy of the apparatus is improved.

  FIG. 2 is an example of experimental results confirming the effects of the present invention. In the figure, the structure resonance (bending, bending, twisting, etc.) of the lens barrel surface plate and the resonance of the mounting equipment such as the illumination system 15, reticle surface plate 22 (bending, bending, twisting, etc.) exist between 150 Hz and 300 Hz. ) Vibration peak (broken line). It can be seen that due to the action of the second vibration control loop according to the present invention, these vibration peaks are damped and the peaks are reduced (solid line). The compensation circuit of the second vibration control loop is controlled by using not only a plurality of bandpass filters that extract only these vibration peaks, but also a low-pass filter and a notch filter for excluding vibration peaks that exist on the high frequency side of 300 Hz or higher. The system stability is improved.

1 shows a configuration of an exposure apparatus according to an embodiment of the present invention. The experimental result which shows the effect of the 2nd vibration loop of this invention. Conventional exposure apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Reticle 2 Reticle stage 3 Wafer 4 Wafer stage 5 Projection optical system 6 Laser interferometer 8 Lens platen 9 Active mount 10 Installation floor 11 Vibration sensor 12 Filter circuit 13 Compensation circuit 14 Drive circuit 15 Illumination system 16 Reaction force receiving structure 17, 19 First linear motor 18, 20 Second linear motor 21, 23, 24 Vibration sensor 22 Reticle surface plate 25 Filter circuit 26 Compensation circuit 101 Reticle 102 Reticle stage 103 Wafer 104 Wafer stage 105 Projection optical system 106 Laser interference Total 107 Focus sensor 108 Lens platen 109 Active mount 110 Installation floor 111 Vibration sensor 112 Filter circuit 113 Compensation circuit 114 Drive circuit 115 Illumination system 116 Reaction force receiving structure 117, 119 Amota 118, 120 second linear motor

Claims (8)

  Support means for supporting vibration isolation of the surface plate, an actuator for driving the surface plate, a vibration sensor for detecting the rigid body vibration mode of the surface plate, and compensating the output of the vibration sensor to generate a driving force for the actuator An active mount comprising: a first vibration control loop; and a vibration sensor for detecting elastic vibration due to structural resonance (bending, bending, twisting, etc.) of the surface plate.   2. The active mount according to claim 1, further comprising a vibration sensor for detecting elastic vibration caused by structural resonance (bending, bending, twisting, etc.) of a structural member or device mounted on the surface plate.   The active mount according to claim 1, wherein the vibration sensor is an accelerometer or a speedometer.   The active mount according to claim 1, further comprising a second vibration control loop that compensates for an output of the vibration sensor and generates a driving force for the actuator.   The active mount according to claim 1, wherein the actuator is a force generating actuator such as a linear motor.   The active mount according to claim 1, wherein the actuator is a displacement-generating actuator such as a piezoelectric element or a giant magnetostrictive element.   The active mount according to claim 1, wherein the driving force generated by the actuator is a viscous force.   An exposure apparatus comprising the active mount according to claim 1.

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