JP4632569B2 - Stage equipment - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a stage apparatus, and more particularly to a stage apparatus suitable for precision equipment such as a charged beam drawing apparatus and a charged beam inspection apparatus that requires high speed movement and high positioning accuracy.
[0002]
[Prior art]
Conventionally, in an accurate positioning device, for example, an XY stage device used in a charged beam drawing device or a charged beam inspection device used in a vacuum, a ceramic having high rigidity and a non-magnetic material is used for highly accurate positioning. An ultrasonic motor is used as a stage constituent member to perform high-speed movement and high-resolution positioning of the stage (see Japanese Patent Laid-Open No. 2000-58629).
[0003]
In the above-described ultrasonic motor drive type stage apparatus, a small stage motor can be realized by using a small ultrasonic motor as compared with a stage apparatus using a screw feed mechanism having an external drive unit.
[0004]
FIG. 4 shows such a stage apparatus. Reference numeral 2 denotes a flat base. A first stage 3 and a second stage 4 are sequentially arranged on the substrate 2, and although not shown, a sample stage for placing a sample such as a semiconductor wafer on the second stage 4. Is installed.
[0005]
A pair of guide rails 20 having a V-groove as shown in FIG. 5 and facing each other below the first stage 3 and a plurality of rollers 21 interposed between the V-grooves of the guide rail in a cross shape. A pair of cross roller guides 5 are arranged in parallel at a predetermined interval, whereby the first stage 3 is movable in the x direction. Similarly, a cross roller guide 6 is disposed below the second stage 4 in parallel with the first stage 3 at a predetermined interval, so that the second stage 4 can move in the y direction. Has been.
[0006]
An ultrasonic motor is used as the driving means for the first stage 3 and the second stage 4. That is, as shown in FIG. 2A, the ultrasonic motor 7 that drives the first stage 3 is disposed on the base 2, and the first driven member 9 that is attached to the lower surface of the first stage 3. When the friction material 10 of the ultrasonic motor 7 is brought into contact with the pressure contact surface 9a and the ultrasonic motor 7 is driven in this state, the friction material 10 moves elliptically in a plane parallel to the first stage 3, The first stage 3 is moved along the cross roller guide 5 (in the x direction) by friction drive with the first driven member 9.
[0007]
As shown in FIG. 2B, the ultrasonic motor 8 that drives the second stage 4 is disposed on the first stage 3 and is attached to the lower surface of the second stage 4. When the friction material 12 of the ultrasonic motor 8 is brought into contact with the pressure contact surface 11 a of the member 11 and the ultrasonic motor 8 is driven in this state, the friction material 12 moves elliptically in a plane parallel to the second stage 4. The second stage 4 is moved along the cross roller guide 6 (in the y direction) by friction driving with the second driven member 11.
[0008]
[Problems to be solved by the invention]
However, in the ultrasonic motor drive type stage apparatus shown in FIG. 4, when the stage is decelerated and stopped in order to move to the next drawing process or inspection process after constant speed driving, the low frequency remaining in the stage apparatus. Since the vibration in the stage traveling direction cannot be attenuated in a short time, it is necessary to interrupt the drawing process and the inspection process until the residual vibration becomes sufficiently small.
[0009]
That is, there has been no problem because the pattern to be drawn has not been required to be so fine in the past. However, in recent years, the pattern to be drawn has been drastically miniaturized, and such a fine pattern can be drawn. When a fine pattern is inspected, the influence of residual vibration is large as long as the conventional stage apparatus is used. When such a conventional stage apparatus is used, the residual vibration is sufficiently reduced. The work had to be interrupted.
[0010]
More specifically, the ultrasonic motor has a structure having a certain elastic coefficient with respect to an external force acting on the friction material in order to stabilize the operation. In particular, a relatively small elastic coefficient is set for the direction perpendicular to the pressure contact direction of the friction material (the direction in which the stage is moved) in order to realize smooth driving. For this reason, the conventional stage apparatus shown in FIG. 4 has a structure in which a heavy stage is supported by a weak spring (ultrasonic motor) with respect to the moving direction of the stage. Residual vibration of low frequency occurred in the direction.
[0011]
2A, the equivalent spring constant in the x direction (perpendicular to the paper surface) of the first ultrasonic motor 7 is K [N / m], and the first stage 3 and the first stage 3 Assuming that the mass of the entire stage including the two stages 4 is M [kg], when the stage is stopped, a residual vibration having an angular frequency Ω = √ (M / K) [rad / sec] in the direction indicated by the white arrow in FIG. It was happening. Here, the natural frequency of the entire stage is given by Ω / 2π (Hz) obtained by dividing the angular frequency Ω by 2π.
[0012]
Further, as apparent from the vibration mode indicated by the white arrow in FIG. 4, the vibration having the angular frequency Ω appears even when the stage is driven at a constant speed in the x direction, and therefore, a scanning process in which drawing / inspection is performed while moving the stage. It was a factor that deteriorated the straightness accuracy.
[0013]
As a means for suppressing the residual vibration, for example, a method of forcibly suppressing the residual vibration by adding a brake mechanism to the stage can be considered. However, the entire stage apparatus is enlarged, and the control mechanism for the entire stage apparatus is further increased. There was a problem of becoming complicated.
[0014]
An object of this invention is to provide the stage apparatus which can attenuate | dampen the vibration to the advancing direction of the stage by an ultrasonic motor rapidly.
[0015]
[Means for Solving the Problems]
The stage apparatus of the present invention is a stage apparatus comprising a base, a stage provided on the base, and an ultrasonic motor that drives the stage, and the stage has a natural frequency that is the same as the natural frequency of the stage. It has a frequency, and the Rutotomoni provided vibration absorber in which the stage damping vibrations of the same direction driven by the ultrasonic motor, suction vibration device, a damping plate, mounted on該制oscillating plate And a weight that vibrates in the same direction as the stage is driven, and a housing to which the damping plate is fixed .
[0016]
A stage driven by an ultrasonic motor generates residual vibration that vibrates at the natural frequency of the stage in the moving direction of the stage when stopped or during driving. In the stage apparatus of the present invention, the natural vibration of the stage is present in the stage. A vibration absorber that attenuates vibrations in the same direction as the stage is driven by an ultrasonic motor is provided. This vibration absorber effectively attenuates residual vibrations of the stage. can do.
[0017]
That is, in view of the fact that the vibration by the ultrasonic motor of the stage is a minute vibration on the order of submicrometers, and that the vibration mode of the problematic vibration can be specified, the natural vibration that is the same as the natural frequency of the stage described above. For example, a small and lightweight vibration absorber (dynamic damper) using a material with high vibration absorption performance as a damping material is provided on the stage device, so that the above-mentioned residual vibration can be achieved without increasing the size of the stage device. Can be controlled.
[0018]
Therefore, the residual vibration when the stage is stopped can be attenuated in a short time, and at the same time, the vibration of the angular frequency Ω generated when the stage is driven at a constant speed can be suppressed, and the wafer processing performance of the drawing apparatus or inspection apparatus can be improved. Can do.
[0019]
In the stage apparatus of the present invention, it is desirable to provide a cavity in the stage and a vibration absorber in the cavity. By adopting such a structure, it is possible to improve the vibration damping effect of the vibration absorber by reducing the weight and weight of the stage.
[0020]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, the stage apparatus of the present invention will be described with reference to FIGS. 1A and 1B show a stage apparatus of the present invention, in which FIG. 1A is a perspective view, FIG. 1B is a perspective view showing a structure inside a vibration absorber, and FIGS. 2A and 2B are views in the x direction of FIG. It is a side view of a side view and ay direction.
[0021]
In the stage apparatus of FIG. 1A, reference numeral 2 denotes a flat plate-like base, and a first stage 3 and a second stage 4 are sequentially stacked on the base 2 and are not shown. A sample stage for placing a sample such as a semiconductor wafer is arranged on the second stage 4.
[0022]
Between the first stage 3 and the base 2, a pair of crosses having a pair of guide rails having a V groove and a plurality of rollers interposed between the V grooves of the guide rail in a cross shape. The roller guides 5 are arranged in parallel in the y direction at a predetermined interval, so that the first stage 3 can be moved in the x direction.
[0023]
Similarly, between the second stage 4 and the first stage 3, a pair of cross roller guides 6 are arranged in parallel at a predetermined interval in the x direction, whereby the second stage 4 is The first stage 3 is movable in the y direction.
[0024]
An ultrasonic motor 7 is disposed on the base 2 as shown in FIG. 2A, and this ultrasonic motor 7 is a friction that moves elliptically in a plane parallel to the first stage 3 (xy plane). When the friction material 10 protrudes the most in the positive y-axis direction, the first material 3 comes into contact with the pressure contact surface 9a of the first driven member 9 attached to the lower surface of the first stage 3. The stage 3 is pushed out in the x direction.
[0025]
Specifically, when the first stage 3 shown in FIG. 2A is moved in the x direction (perpendicular to the paper surface), the first stage 3 attached to the lower surface of the first stage 3 in parallel with the cross roller guide 5 is used. 1 The friction material 10 of the first ultrasonic motor 7 is brought into contact with the pressure contact surface 9a of the driven member 9, and in this state, the first ultrasonic motor 7 is driven to cause the friction material 10 to move elliptically. The first stage 3 is moved along the first cross roller guide 5 by friction drive with the first driven member 9.
[0026]
Further, an ultrasonic motor 8 is arranged on the first stage 3 as shown in FIG. 2B, and this ultrasonic motor 8 is in a plane parallel to the second stage 4 (xy plane). The friction material 12 has an elliptical motion. When the friction material 12 protrudes most in the negative x-axis direction, the friction material 12 abuts against the pressure contact surface 11a of the second driven member 11 attached to the lower surface of the second stage 4. Then, the second stage 4 is pushed out in the y direction.
[0027]
Specifically, when the second stage 4 is moved in the y direction, the second stage 4 is moved in the second direction with respect to the pressure contact surface 11 a of the second driven member 11 attached to the lower surface of the second stage 4 in parallel with the cross roller guide 6. The friction material 12 of the ultrasonic motor 8 is brought into contact, and in this state, the second ultrasonic motor 8 is driven to make the friction material 12 move elliptically, and the second stage 4 is driven by friction with the second driven member 11. Is moved along the second cross roller guide 6.
[0028]
In the stage apparatus of the present invention shown in FIG. 1, the second stage 4 has the same natural frequency as the natural frequency of the entire stage including the first stage 3 and the second stage 4 installed on the first stage 3. A vibration absorber 14 having a maximum vibration damping action in the x direction is provided so as to attenuate vibrations in the same direction as the x direction in which the first stage 3 is driven by the first ultrasonic motor 7. It has been. That is, the vibration absorber 14 shown in FIG. 1B is installed in the cavity 13 formed in the second stage 4 in the direction in which the vibration damping action is maximized.
[0029]
The vibration absorber 14 includes a damping plate 15 made of a damping material, a weight 16 attached to a central portion of the damping plate 15, and a bottomed housing that fixes a vibration absorbing portion made of the damping plate 15 and the weight 16. 17, the natural angular frequency ω = √ (k / m) where the equivalent spring constant in the x direction of the damping plate 15 is k [N / mm] and the mass of the weight 16 is m [kg]. [Rad / sec] is the same as the natural angular frequency Ω of the entire stage including the first stage 3 and the second stage 4 installed on the first stage 3.
[0030]
Since the weight 16 of the vibration absorber 14 vibrates in the x direction, that is, the vibration damping plate 15 vibrates as shown by a one-dot chain line in FIG. 1B, the natural angular frequency ω of the vibration absorber 14 is set to the stage. As shown in FIG. 1 (a), the vibration of the entire stage including the first stage 3 and the second stage 4 installed on the first stage 3 is not only made equal to the entire natural angular frequency Ω. By matching the direction (x direction) with the vibration direction of the weight 16 of the vibration absorber 14, the maximum vibration damping effect can be obtained.
[0031]
The casing 17 is desirably made of a lightweight and highly rigid material such as ceramics in order to compensate for a decrease in rigidity of the second stage 4 due to the provision of the hollow portion 13.
[0032]
The cavity 13 is provided to reduce the weight of the entire stage and bury the vibration absorber 14 at the same time, but by installing the small and light vibration absorber 14 of the present invention in an existing cavity such as the maintenance opening 19. The vibration characteristics of the stage can be easily improved.
[0033]
Further, in the stage apparatus shown in FIG. 1A, the vibration absorbing device 14 is embedded only in the second stage 4, but the first stage 3 is provided with a cavity similar to the cavity 13 of the second stage 4. By providing the vibration absorbers 14 in both the first stage 3 and the second stage 4, it is possible to reduce the weight of the entire stage and further improve the vibration damping effect.
[0034]
The stage apparatus configured as described above, for example, places a sample such as a semiconductor wafer on which a pattern is formed on the second stage 4 and drives the ultrasonic motor 7 to move the first stage 3. At the same time, the ultrasonic motor 8 is driven to move the second stage 4 so that the second stage 4 is moved at high speed and positioned with high resolution.
[0035]
The cavity 13 provided in the second stage 4 houses a vibration absorber 14 having a weight 16 that vibrates in the x direction, and the natural frequency of the vibration absorber 14 is the same as the natural frequency of the entire stage. Therefore, the residual vibration generated when the first stage 3 is stopped can be attenuated in a short time, and at the same time, the vibration of the angular frequency Ω generated when the stage is driven at a constant speed can be suppressed. Can be improved.
[0036]
Further, in the stage apparatus of the present invention, the cavity 13 is provided in the second stage 4 and the vibration absorber 14 is provided in the cavity 13, so that the vibration absorber 14 is controlled by reducing the weight and weight of the second stage 4. The vibration effect can be improved.
[0037]
The stage device shown in FIGS. 1 and 2 uses cross roller guides 5 and 6 installed by a method in which the V groove is opposed in the vertical direction (z direction) and preload is applied by the weight of the stage. Depending on the purpose, either a stage device using a cross roller guide installed by a method in which V grooves are opposed in the horizontal direction (x direction or y direction) and preloading is applied from the outside, either the first stage or the second stage It may be a stage apparatus having only these. In the case of a stage apparatus having only one of the first stage and the second stage, it is necessary to match the natural frequency of the vibration absorber 14 with the natural frequency of the first stage or the second stage.
[0038]
Further, in the stage apparatus having the first and second stages 3 and 4 as shown in FIG. 1, it is possible to provide a vibration absorber only in the first stage. In this case, the natural vibration of the vibration absorber is provided. The number needs to match the natural frequency of the entire stage including the first and second stages 3 and 4.
[0039]
In the above example, the example using the cross roller guides 5 and 6 has been described. However, in the present invention, it is a matter of course that a stage apparatus using another moving guide mechanism such as a static pressure bearing may be used. .
[0040]
Further, the shape of the vibration damping plate 15 shown in FIG. 1B is a simple leaf spring. However, in order to enhance the vibration damping effect or by adjusting the equivalent spring constant of the vibration damping plate 15, the vibration damping plate 14 has a unique shape. In order to adjust the angular frequency ω, a damping plate 18 having a perforated structure as shown in FIG. 3A may be used. Further, since the damping plates 15 and 18 have a thin plate-like structure, it is desirable to use ceramics or a damping alloy as a material that is excellent in workability and has a high vibration damping capability and does not generate unnecessary gas in a vacuum. .
[0041]
Further, as shown in FIG. 3B, the vibration damping effect can be further improved by providing a plurality of vibration absorbing portions including the vibration damping plate 15 and the weight 16 inside the bottomed housing 17 of the vibration absorbing device 14. Can do.
[0042]
【The invention's effect】
As described above, the stage driven by the ultrasonic motor generates residual vibration that vibrates at the natural frequency of the stage in the moving direction of the stage when stopped or during driving, but in the stage apparatus of the present invention, Since a vibration absorbing device having the same natural frequency as that of the stage and attenuating the vibration in the direction in which the stage is driven by the ultrasonic motor is provided, the vibration absorbing device can reduce the low-frequency residual vibration of the stage. Can be effectively attenuated.
[Brief description of the drawings]
1A and 1B show a stage apparatus of the present invention, in which FIG. 1A is a perspective view of the stage apparatus, and FIG. 1B is a perspective view showing the inside of a vibration absorber.
2 is a side view of the stage apparatus of FIG. 1, wherein (a) is a side view seen from the x direction, and (b) is a side view seen from the y direction.
FIG. 3 is a perspective view showing another example of a vibration absorber used in the stage device of the present invention.
FIG. 4 is a perspective view showing a conventional stage apparatus.
FIG. 5 is an exploded perspective view showing a cross roller guide.
[Explanation of symbols]
2 ... Base 3 ... First stage 4 ... Second stage 7, 8 ... Ultrasonic motor 13 ... Cavity 14 ... Vibration absorber

Claims (2)

In a stage apparatus comprising a base, a stage provided on the base, and an ultrasonic motor that drives the stage, the stage has a natural frequency that is the same as the natural frequency of the stage, and the Rutotomoni provided vibration absorber in which the stage damping vibrations of the same direction driven by the ultrasonic motor, suction vibration device, a damping plate, mounted on該制oscillating plate, the stage is driven A stage apparatus comprising: a weight that vibrates in the same direction as the direction to be moved; and a housing to which the damping plate is fixed . The stage apparatus according to claim 1, wherein a cavity is provided in the stage, and the vibration absorber is provided in the cavity.

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