JP2004140290A - Stage device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a stage device in which position control can be continuously performed with high precision. <P>SOLUTION: The stage device moving a stage 2 comprises first and second position measuring instruments 4 and 5 which measure the position of the stage 2 in a Z-direction orthogonal to the surface of the stage 2, and a switch 10 switching the position measuring instrument to the other one when measuring condition of one of the first and the second position measuring instruments 4 and 5 gets out of a specified condition. Based on the output of the position measuring instrument selected by the switch 10, the position of the stage 2 in the Z-direction is moved. <P>COPYRIGHT: (C)2004,JPO

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention generally relates to a stage apparatus, and more particularly, to exposing a workpiece using the same.
[0002]
[Prior art]
2. Description of the Related Art In various measuring instruments and projection exposure apparatuses used in a semiconductor lithography process, a stage device which mounts an object to be measured or a workpiece such as a wafer and moves and positions an object with high speed and high accuracy is used.
[0003]
FIG. 1 is a schematic view of a conventional stage device. The conventional stage apparatus includes an XY stage 1 that is driven with high accuracy in the X and Y directions to sequentially expose a pattern on a wafer surface, and Z, ωX, And a stage 2 that can be driven in the tilt directions .omega. These are configured to be driven on the stage base 3.
[0004]
The stage 2 needs to perform high-precision position control in order to print an accurate image on a mounted wafer. Therefore, it is necessary to drive and control the position of the stage based on data obtained by measuring the position with high precision. A laser interferometer is used for position measurement in the X, Y, ωX, and ωY directions. Conventionally, a linear encoder or the like has been used for position measurement in the Z direction. However, a method using the laser interferometer 4 has been proposed in order to achieve higher accuracy. By using the laser interferometer 4, a highly accurate measurement system can be constructed even in the position measurement in the Z direction.
[0005]
[Problems to be solved by the invention]
However, in a length measuring means using a laser interferometer, it is necessary to irradiate a laser beam to a measurement target to reflect the laser beam, and thus it is necessary to mount a mirror on the measurement target. Since the mirror must always be able to reflect the laser within the drive range of the stage, it can reflect the laser even when driven outside the exposure area, such as a wafer supply / recovery position, where high control accuracy is not required. Requires a large-sized mirror. When a large-sized mirror is mounted on the stage, the balance of the stage is deteriorated, which causes the control accuracy to deteriorate. Further, when a highly accurate mirror is produced, there is a disadvantage that the cost increases in proportion to the size of the mirror.
[0006]
Also, in a measurement system using a laser interferometer, measurement with laser light cannot be performed because the laser path of the interferometer is blocked, or the stage is greatly tilted in the tilt direction, and the laser optical axis is out of the measurement range. In such a case, the servo of the stage is turned off immediately and the control becomes impossible. Therefore, after that, unless the initial position drive including the reset of the laser interferometer is performed, the state where the stage can be driven is not restored. Therefore, if a wafer is present on the stage immediately before the control becomes impossible, the wafer cannot be collected by an exposure sequence or the like, and an excessive amount of time is required to recover the apparatus.
[0007]
The present invention has been made in view of the above problems, and has as its object to provide a stage device that can continuously perform high-accuracy position control.
[0008]
[Means for Solving the Problems]
In order to achieve the above object, the present invention relates to a stage device for moving a stage, comprising: first and second position measuring devices for measuring a position in a Z direction orthogonal to a surface of the stage; When a measurement state of any one of the two position measuring devices deviates from a predetermined condition, a switching device that switches to the other position measuring device, based on an output of the position measuring device selected by the switching device, The position of the stage in the Z direction is moved.
[0009]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.
[0010]
(1st Embodiment)
FIG. 2 is a conceptual diagram showing the configuration of the stage device according to the first preferred embodiment of the present invention.
[0011]
In the first embodiment, the stage device includes a stage 2, a laser interferometer 4 as a first position measuring device for detecting the position of the stage 2, and a counter 12 for detecting the position thereof. It has a linear encoder 5 as a two-position measuring device and a counter 16 thereof, and an actuator 8 for generating a driving force in the Z direction.
[0012]
The measurement mirror 6 of the laser interferometer 4 is mounted on the stage 2. The measurement laser 7 of the laser interferometer 4 irradiates the measurement mirror 6 to measure a displacement or the like when the stage 2 is driven in the Z direction. The measuring mirror 6 is large enough to reflect the laser during a predetermined process (for example, when the stage device is applied to the exposure apparatus, while driving inside the exposure area, etc.). Further, the counter 16 of the linear encoder 5 is reset at the same time as the laser interferometer 4 at the time of the initialization operation, so that the position can be measured. The linear encoder 5 may be configured so that a part of the measurement range overlaps with the measurement range of the laser interferometer 4.
[0013]
The controller 9 includes a measurement value capturing unit 10 as a switching unit therein. The measurement value capturing unit 10 can switch between the laser interferometer 4 and the linear encoder 5. In the normal Z-direction position control, the control is switched so that the control is performed based on the measurement value from the counter 12 of the laser interferometer 4. The controller 9 fetches the measurement value from the laser interferometer 4 into the calculation unit 11 and instructs the actuator 8 based on the measurement value and the drive target value to drive the stage 2 to the target value. With such a control loop, servo control in the Z direction is performed on the stage 2.
[0014]
Here, as shown in FIG. 3, when the stage 2 is driven to a position where the supply and recovery of the wafer is performed, the measurement laser 7 from the laser interferometer 4 is moved from the mirror 6 mounted on the stage 2. It will come off. Here, the position of the stage 2 in the X direction and / or the Y direction is controlled by the laser interferometer 13. According to the information from the laser interferometer 13, the controller 9 uses the measured value reading unit 10 to read the linear encoder 5 from the counter 12 of the laser interferometer 4 before the measurement laser 7 for Z-direction measurement comes off the mirror 6. Switching to the counter 16 is possible. Thus, the controller 9 can continuously obtain the position signal for performing the drive control in the Z direction, and can continuously perform the drive control in the Z direction. Thus, for example, the laser interferometer 4 and the linear encoder 5 are connected inside and outside a drive area (for example, when a stage device is applied to an exposure apparatus, this means an exposure area; the same applies hereinafter). It can be used by switching.
[0015]
The controller 9 changes the position measuring device in the Z direction from the laser interferometer 4 to the linear encoder in accordance with any one of the XY coordinates, the Z direction position, the tilt position, and the inclination of the stage 2. 5, the position of the stage 2 in the Z direction may be controlled based on the measurement result of the linear encoder 5. Further, the controller 9 may be configured to switch from the counter 12 of the laser interferometer 4 to the counter 16 of the linear encoder 5 while driving the stage 2 outside the driving area.
[0016]
As described above, according to the present embodiment, when one measurement state of the position measuring device that measures the position of the stage in the Z direction deviates from the predetermined condition, it is possible to switch to the other position measuring device. As a result, even when one of the position measuring devices cannot be measured, for example, the other position measuring device can continue to drive the stage. In addition, since the laser interferometer 4 can be switched to the linear encoder 5 in driving outside the driving area, the size of the mirror can be reduced. Furthermore, since the laser interferometer 4 and the linear encoder 5 can be switched between the inside and outside of the drive area, an appropriate position measuring device can be selected according to the processing. Thus, according to the present embodiment, it is possible to realize simplification of the configuration of the position measuring device, reduction in sensor cost, improvement in control accuracy, prevention of reduction in productivity due to device stoppage, and the like.
[0017]
(Second embodiment)
FIG. 4 is a conceptual diagram showing a configuration of a stage device according to a preferred second embodiment of the present invention, and the same parts as those in the first embodiment are denoted by the same reference numerals.
[0018]
In the second embodiment, the laser interferometer 4 as the first position measuring device and the linear encoder 5 as the second position measuring device have a preset mechanism 15 that can preset measurement values from the respective counters 12 and 16 to each other. . When the position measuring device is switched from the laser interferometer 4 to the linear encoder 5, as shown in FIG. The position data (position data) is preset from the counter 12 of the linear encoder 5 to the counter 16 of the linear encoder 5. When the position measuring device is switched from the linear encoder 5 to the laser interferometer 4, as shown in FIG. 4, the linear encoder 5 is moved by the preset mechanism 15 at a position where the laser interferometer 4 and the linear encoder 5 can simultaneously measure. The position data (position data) is preset from the counter 16 of the laser interferometer 4 to the counter 12 of the laser interferometer 4.
[0019]
As described above, according to the present embodiment, control can be smoothly continued even when the position measuring device is switched.
[0020]
(Third embodiment)
FIG. 5 is a conceptual diagram showing a configuration of a stage device according to a preferred third embodiment of the present invention, and the same parts as those in the first embodiment are denoted by the same reference numerals.
[0021]
If the measurement laser beam 7 of the laser interferometer 4 as the first position measuring device described above is interrupted by some obstacle 14 or the like and measurement is not performed normally, thereafter, the laser interferometer 4, the drive control cannot be performed based on the measurement value. Therefore, in the third embodiment, when the correct measurement by the laser interferometer 4 becomes impossible, as shown in FIG. 4, the control unit 9 changes the state to an error output from the laser interferometer counter 12. Detection is performed based on the signal, and the measurement value reading unit 10 is used to immediately switch from the counter 12 of the laser interferometer 4 to the counter 16 of the linear encoder 5. Thereby, the calculation unit 11 of the control unit 9 can continuously obtain correct position information (measurement signal). Therefore, thereafter, the controller 9 can perform drive control in the Z direction based on the measurement signal of the linear encoder 5.
[0022]
As described above, according to the present embodiment, even when the measurement cannot be performed by the laser interferometer, the position control in the Z direction can be performed without stopping the apparatus.
[0023]
If the laser interferometer 4 can perform correct measurement after switching to control by the linear encoder 5, as shown in FIG. 6, the controller 9 controls the counter 16 of the linear encoder 5 at that time. May be provided in the counter 12 of the laser interferometer 4. As a result, the position measuring device is switched from the linear encoder 5 to the laser interferometer 4 by the measurement value reading unit 10, and the position measurement by the laser interferometer 4 becomes possible again. By performing the above control, the stage control can be continuously performed.
[0024]
After switching to the control by the linear encoder 5, in the control in the Z direction, if the accuracy required for processing such as exposure cannot be satisfied, the processing can be stopped. In this case, after the wafer is collected, the reset operation of the laser interferometer 4 is performed, and the control by the laser interferometer 4 can be returned again. Also in this case, since the control is performed by the linear encoder 5, the reset sequence can be automatically executed. Further, when a difference between the measured values of the laser interferometer 4 and the linear encoder 5 is held as an offset parameter, and one of the position measuring devices of the laser interferometer 4 and the linear encoder 5 is switched to the other position measuring device, May reflect the offset parameter in position measurement data.
[0025]
(Fourth embodiment)
In the present embodiment, the stage device roughly replaces part of the configuration of the stage device according to the first, second, and third embodiments with another configuration. That is, in the first, second, and third embodiments described above, the linear encoder 5 is shown as the second measuring means 5, but the present invention is not limited to this. The same effect can be obtained by replacing the means 5 with a laser interferometer, a laser displacement meter, an ultrasonic sensor, a magnetostrictive sensor, a capacitance sensor, an eddy current sensor, or the like.
[0026]
(Other embodiments)
FIG. 7 is a schematic diagram showing a configuration of an exposure apparatus when the positioning apparatus of the present invention is applied to an exposure apparatus used in a semiconductor device manufacturing process. In FIG. 7, light emitted from an illumination optical system 3001 is irradiated on a reticle 3002 as an original. The reticle 3002 is held on a reticle stage 3003, and the pattern of the reticle 3002 is reduced and projected at the magnification of the reduction projection lens 3004, and the image plane of the reduction projection lens 3004 that forms a reticle pattern image on the image plane is in the Z direction. Is perpendicular to A resist is applied to the surface of the substrate 3005 which is a sample to be exposed, and shots formed in the exposure step are arranged. The substrate 3005 to be controlled is placed on the stage 2. The stage 2 includes a chuck for fixing the substrate 3005, an XY stage as a driver that can move horizontally in the X-axis direction and the Y-axis direction, and the like.
[0027]
(Embodiment)
Examples of embodiments according to the present invention are listed below.
[0028]
[Embodiment 1] A stage device for moving a stage,
First and second position measuring devices for measuring a position in a Z direction orthogonal to a surface of the stage;
A switch that switches to the other position measuring device when the measurement state of any one of the first and second position measuring devices deviates from a predetermined condition;
With
A stage apparatus for moving a position in the Z direction of the stage based on an output of a position measuring device selected by the switching device.
[0029]
[Embodiment 2] The switch according to Embodiment 1, wherein the switching device switches between the first position measuring device and the second position measuring device inside and outside a predetermined driving area. Stage equipment.
[0030]
[Embodiment 3] When switching any one of the first and second position measuring devices to the other position measuring device, the measurement data of one position measuring device is preset to the other position measuring device. The stage device according to the first embodiment, further comprising a mechanism for performing the operation.
[0031]
[Embodiment 4] The difference between the measured values of the first and second position measuring devices is held as an offset parameter, and one of the first and second position measuring devices is used for measuring the other position. The stage apparatus according to embodiment 3, wherein the offset parameter is reflected in position measurement data when switching to a stage.
[0032]
[Embodiment 5] The switching device switches the Z-direction position measuring device to the second position measuring device when the first position measuring device cannot measure. Stage equipment.
[0033]
[Embodiment 6] The switching device performs a first position measurement of a Z-direction position measuring device in accordance with at least one of XY coordinates, a Z-direction position, a tilt-direction position, and a tilt of the stage. The stage device according to the first embodiment, wherein the stage device is switched to the second position measuring device.
[0034]
[Embodiment 7] An optical system for projecting exposure light applied to a pattern-formed original onto a substrate,
A stage device that holds the substrate or the original plate and moves a stage,
With
The stage device,
First and second position measuring devices for measuring a position in a Z direction orthogonal to a surface of the stage;
A switch that switches to the other position measuring device when the measurement state of any one of the first and second position measuring devices deviates from a predetermined condition;
With
An exposure apparatus, wherein a position in the Z direction of the stage is moved based on an output of a position measuring device selected by the switching device.
[0035]
【The invention's effect】
As described above, according to the present invention, it is possible to provide a stage device capable of continuously performing high-accuracy position control.
[Brief description of the drawings]
FIG. 1 is a diagram showing a schematic view of a conventional stage device.
FIG. 2 is a conceptual diagram showing a configuration of a stage device according to a preferred first embodiment of the present invention.
FIG. 3 is a conceptual diagram showing a configuration of a stage device according to a preferred first embodiment of the present invention.
FIG. 4 is a conceptual diagram showing a configuration of a stage device according to a preferred second embodiment of the present invention.
FIG. 5 is a conceptual diagram showing a configuration of a stage device according to a preferred third embodiment of the present invention.
FIG. 6 is a conceptual diagram showing a configuration of a stage device according to a preferred third embodiment of the present invention.
FIG. 7 is a conceptual diagram when a stage device according to a preferred embodiment of the present invention is applied to an exposure apparatus.
[Explanation of symbols]
1 XY stage 2 Z, ωX, ωY tilt stage 3 Stage base 4 First position measuring device in Z direction (laser interferometer)
5 Second position measuring instrument in Z direction (linear encoder)
6 Interferometer mirror for Z direction measurement 7 Interferometer measurement laser for Z direction measurement 8 Z direction drive actuator 9 Controller 10 Measurement value reading unit (switch)
DESCRIPTION OF SYMBOLS 11 Operation part 12 Laser interferometer counter 13 Laser interferometer counter 14 Obstacle to laser light 15 First and second measurement value preset mechanism 16 Counter of second position measuring instrument

Claims (1)

A stage device for moving a stage,
First and second position measuring devices for measuring a position in a Z direction orthogonal to a surface of the stage;
A switch that switches to the other position measuring device when the measurement state of any one of the first and second position measuring devices deviates from a predetermined condition;
With
A stage apparatus for moving a position of the stage in the Z direction based on an output of a position measuring device selected by the switching device.

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