JP5953177B2 - Sample stage and charged particle device - Google Patents

Description

  The present invention relates to a charged particle device such as an electron microscope, and more particularly to a sample stage provided in the charged particle device.

  With the recent miniaturization of semiconductor elements, not only manufacturing apparatuses but also inspection and evaluation apparatuses are required to have high precision corresponding thereto. For example, in order to evaluate whether or not the shape dimension of a pattern formed on a semiconductor wafer is correct, a scanning electron microscope having a length measuring function (hereinafter referred to as a length measuring SEM) is used.

  When a sample is evaluated using a length measuring SEM, the positioning accuracy of the sample stage greatly affects the measurement accuracy such as the resolution of the observation image and the pattern dimensions. In particular, even when the sample stage is stopped at a predetermined position for sample observation, if minute vibration is generated in the stage, the image quality of the observation image is deteriorated by the vibration.

  Therefore, it is effective to use a fine movement mechanism capable of positioning with higher accuracy than the positioning mechanism of the sample stage. For example, Patent Document 1 describes a fine movement mechanism that combines a piezoelectric actuator capable of controlling a minute displacement and an elastic support mechanism. This document proposes a method that enables driving in both the X direction and the Y direction by using a double structure of a fine movement mechanism that enables driving in one direction.

  Further, Patent Document 2 proposes a sample stage that achieves positioning in the X direction and the Y direction by using a piezoelectric actuator and an elastic support portion for the purpose of positioning a sample for a scanning probe microscope. ing. In this example, the elastic support portion is configured to be displaceable in both the X direction and the Y direction, and the piezo actuator and the elastic support portion are arranged in series to enable driving in the X direction and the Y direction.

JP 2010-123354 A JP 2010-190657 A

  In the fine movement mechanism of the sample stage device, the top table may vibrate in the pitching direction (rotation direction in the vertical plane). Accordingly, when a positioning error occurs, the observation image is deteriorated. In order to suppress minute vibrations in the pitching direction of the stage, it is necessary to review the shape and arrangement of the elastic support portion of the fine movement mechanism.

  The present invention has been made in view of the above circumstances, and is intended to realize a sample stage capable of suppressing the minute vibration of the top table on which the sample is mounted and improving the image quality of the observed image or the accuracy of the dimension measurement value. An object is to provide a minute vibration removing mechanism.

  The minute vibration removing mechanism includes a movable part attached to the top table, a fixed part attached to the intermediate table, an elastic support part for elastically supporting the movable part with respect to the fixed part, and movable relative to the fixed part. A piezoelectric actuator that drives the portion, and the elastic support portion is arranged to connect the four corners of the fixed portion and the four corners of the movable portion, and the piezoelectric actuator is collinear on both sides of the fixed portion in the X-axis direction. A pair of X-axis piezoelectric actuators that extend along opposite directions and extend in opposite directions to each other, and a pair of Y-axis that extend along the same straight line on both sides in the Y-axis direction of the fixed portion and extend in opposite directions And a piezoelectric actuator.

  According to the present invention, a minute stage for realizing a sample stage capable of improving the image quality of an observation image or the accuracy of a dimension measurement value by suppressing the minute vibration without reducing the moment rigidity of the top table on which the sample is mounted. A vibration removal mechanism is provided.

It is a figure which shows the example of the charged particle beam apparatus provided with the sample stage which has the micro vibration removal mechanism of this invention. It is a figure which shows the example of a structure of the sample stage apparatus which has the micro vibration removal mechanism of this invention. It is a figure which shows the plane structure of the 1st example of the micro vibration removal mechanism of this invention. It is a figure which shows the cross-sectional structure of the 1st example of the micro vibration removal mechanism of this invention. It is a figure which shows the planar structure of the 2nd example of the micro vibration removal mechanism of this invention. It is a figure which shows the cross-sectional structure of the 2nd example of the micro vibration removal mechanism of this invention. It is a figure which shows the planar structure of the 3rd example of the micro vibration removal mechanism of this invention. It is a figure which shows the cross-sectional structure of the 3rd example of the micro vibration removal mechanism of this invention. It is a figure explaining the moment rigidity in the minute vibration removal mechanism of this invention. It is a figure explaining the moment rigidity in the minute vibration removal mechanism of this invention. It is a figure explaining the moment rigidity in the minute vibration removal mechanism of this invention. It is a figure explaining the moment rigidity in the minute vibration removal mechanism of this invention. It is a figure explaining the moment rigidity in the minute vibration removal mechanism of this invention. It is a figure explaining the moment rigidity in the minute vibration removal mechanism of this invention. It is a figure explaining the example of the hysteresis characteristic of a piezoelectric actuator. It is a figure explaining the example of the voltage applied to a piezoelectric actuator. It is a figure explaining the example of the displacement of a piezoelectric actuator. It is a figure explaining the relationship between the applied voltage and displacement of the 1st piezoelectric actuator in the micro vibration removal mechanism of this invention. It is a figure explaining the relationship between the applied voltage and displacement of the 2nd piezoelectric actuator in the micro vibration removal mechanism of this invention. It is a figure which shows the example of the step voltage applied to the 1st piezoelectric actuator in the minute vibration removal mechanism of this invention. It is a figure which shows the example of the step voltage applied to the 2nd piezoelectric actuator in the minute vibration removal mechanism of this invention. It is a figure explaining the displacement of the movable part in the minute vibration removal mechanism of this invention. It is an example of the block diagram of the control system of the minute vibration removal mechanism of this invention. It is a figure which shows the relationship between the length measurement sequence in the side length SEM of this invention, and the vibration of the top table of a stage. It is an example of a structure of the minute vibration removal mechanism using a rod. It is an example of how to attach the piezoelectric actuator to the outer frame. It is a figure which shows the planar structure of the micro vibration removal mechanism using a rod. It is a figure which shows the cross-sectional structure of the micro vibration removal mechanism using a rod. It is a figure which shows the planar structure of the micro vibration removal mechanism which does not use a rod. It is a figure which shows the cross-sectional structure of the micro vibration removal mechanism which does not use a rod. It is a figure explaining the shear load concerning the piezoelectric actuator of the micro vibration removal mechanism using a rod. It is a figure explaining the shear load concerning the piezoelectric actuator of the micro vibration removal mechanism which does not use a rod. It is a figure explaining each parameter in calculation of the stroke of a rod length and a minute vibration removal mechanism. It is a figure which shows the calculation result of the stroke of a rod length and a minute vibration removal mechanism. It is a figure explaining the example which devises the shape of a rod. It is a figure explaining the design method for lengthening a rod. It is a figure explaining the Example which increases the rod and piezoelectric actuator of + X direction, and enables control of a rotation direction. It is a figure explaining the Example which adds a rod and a piezoelectric actuator also to a Z direction, and performs three-axis movement.

  With reference to FIG. 1, the example of the charged particle apparatus of this invention is demonstrated. Here, a length measurement SEM will be described as an example of a charged particle device. The side length SEM of this example includes a lens barrel 11 that houses an optical system of a scanning electron microscope, and a vacuum chamber 12 connected to the lens barrel 11. A sample stage device is provided in the vacuum chamber 12.

  The sample stage apparatus has a top table 101 and an intermediate table 103, and a minute vibration removing mechanism 102 is provided between them. A sample 110 such as a wafer to be observed is placed on the top table 101. The intermediate table 103 is driven with respect to the base in the vacuum chamber 12 by a stage mechanism 107 including a linear motor and a linear guide, as indicated by an arrow B.

  The minute vibration removing mechanism 102 includes a piezoelectric actuator 102a and a fixing member 102b. The fixing member 102b is mounted on the intermediate table 103. The piezoelectric actuator 102a is mounted between the top table 101 and the fixed member 102b.

  The sample stage device is provided with a position detection device that detects the position of the top table 101. The position detection apparatus of this example includes a flat mirror 111 provided on the top table 101 and a laser interferometer 112 provided on the vacuum chamber 12. The laser light from the laser interferometer 112 is reflected by the plane mirror 111 and returns to the laser interferometer 112 again. The laser interferometer 112 is configured to detect the displacement and position of the top table 101 from the transmitted laser light and the reflected laser light. Here, a configuration including a plane mirror and a laser interferometer has been described as an example of a position detection device, but other configurations may be used.

  When observing the sample 110 with the length measuring SEM, the stage mechanism 107 positions the sample. The current position of the top table 101 is accurately measured by the laser interferometer 112 and sent to the control unit 113. The control unit 113 drives the linear motor of the stage mechanism 107 based on the current position of the top table 101. In this way, the observation position on the sample 110 is arranged on the optical axis of the optical system of the scanning electron microscope by the feedback control system including the position detection device, the control unit 113, and the stage mechanism 107.

  An electron beam from the optical system of the scanning electron microscope is irradiated onto the sample 110. Secondary electrons generated from the sample 110 are detected by a detector, and a scanned image is obtained. In this way, information such as the line width of the circuit pattern on the sample 110 can be acquired.

  The intermediate table 103 is always driven by the linear motor of the stage mechanism 107. Therefore, minute vibrations are continuously transmitted from the linear motor to the intermediate table 103. When the intermediate table 103 vibrates, the top table 101 vibrates. This affects the positioning accuracy of the top table 101. Therefore, in this example, the minute vibration removing mechanism 102 is provided to remove the residual vibration generated by driving the intermediate table 103.

  In the length measurement SEM of this example, the displacement of the top table 101 is detected by the laser interferometer 112 and sent to the control unit 113. The control unit 113 controls the voltage applied to the piezoelectric actuator 102a so as to reduce the displacement of the top table 101. Thus, the applied voltage of the piezoelectric actuator 102a is controlled by the control signal from the control unit 113, and the displacement of the top table 101, that is, the vibration is suppressed.

  As shown by the arrow A, the top table 101 is driven in the same driving direction as the driving direction of the intermediate table 103 (arrow B) by the minute vibration removing mechanism 102. The intermediate table 103 is driven by a linear motor of the stage mechanism 107, and its stroke is on the order of several hundred millimeters. On the other hand, the top table 101 is driven by the piezoelectric actuator 102a of the minute vibration removing mechanism 102, and its stroke is about several tens of nanometers and is high speed.

  With reference to FIG. 2, the example of a structure of the sample stage apparatus by this invention is demonstrated. The sample stage apparatus has a top table 201 and an intermediate table 203, and the intermediate table 203 is driven by a stage mechanism provided therebelow. The sample stage device is mounted on the base 205. A minute vibration removing mechanism 202 is provided between the top table 201 and the intermediate table 203. A wafer 210 as a sample is mounted on the top table 201. As shown, the X axis and the Y axis are taken along the upper surface of the base 205, and the Z axis is taken vertically upward.

  On the top table 201, an X-axis plane mirror 211a and a Y-axis plane mirror 211b are mounted. An X-axis laser interferometer 212a and a Y-axis laser interferometer 212b are attached to the lens barrel. The position of the top table 201 is measured by an X-axis laser interferometer 212a and a Y-axis laser interferometer 212b.

  On the base 205, a pair of X-axis linear guides 208c and 208d which are guides in the X-axis direction are mounted. The X-axis linear guide includes a rail 208c and a movable portion 208d, and an X-axis intermediate slider 206 that is movable in the X-axis direction is fixed to the movable portion 208d. The X-axis intermediate slider 206 is driven in the X-axis direction by two X-axis linear motors 208e that generate thrust in the X-axis direction. A pair of Y-axis linear guides 206a and 206b, which are guides in the Y-axis direction, are mounted on the X-axis intermediate slider 206. The Y-axis linear guide includes a rail 206a and a movable portion 206b, and an intermediate table 203 is fixed to the movable portion 206b.

  On the base 205, a pair of Y-axis linear guides 209a and 209b, which are guides in the Y-axis direction, are mounted. The Y-axis linear guide includes a rail 209a and a movable portion 209b, and a Y-axis intermediate slider 208 that is movable in the Y-axis direction is fixed to the movable portion 209b. The Y-axis intermediate slider 208 is driven in the Y-axis direction by two Y-axis linear motors 209e that generate thrust in the Y-axis direction. On the Y-axis intermediate slider 208, a pair of X-axis linear guides 208a and 208b that are guides in the X-axis direction are mounted. The X-axis linear guide includes a rail 208a and a movable portion 208b, and an intermediate table 203 is fixed to the movable portion 208b.

  The intermediate table 203 is fixed to the movable portion 208b of the X-axis linear guide and the movable portion 206b of the Y-axis linear guide. Note that the X-axis intermediate slider 206 and the Y-axis intermediate slider 208 can move independently of each other. When the X-axis intermediate slider 206 moves in the X-axis direction, the intermediate table 203 moves along with the X-axis direction. When the Y-axis intermediate slider 208 moves in the Y-axis direction, the intermediate table 203 moves along with the Y-axis direction.

  The structure of the minute vibration removing mechanism according to the present invention will be described with reference to FIGS. 3A and 3B. FIG. 3A is a cross-sectional view showing a planar configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line AA of FIG. FIG. 3B is a diagram showing a cross-sectional configuration of the micro-vibration removing mechanism of this example viewed from the cutting line BB in FIG. 3A. As shown, the X axis and the Y axis are taken along the upper surface of the base 319, and the Z axis is taken vertically upward.

  The minute vibration removing mechanism of the present example includes a plate-like fixed portion 304 and an outer frame movable portion 306 arranged so as to surround it. A top plate 301 is mounted on the upper surface of the outer frame movable unit 306. The outer frame movable portion 306 and the top plate 301 are movable with respect to the fixed portion 304.

  The fixing unit 304 is fixed on the intermediate table 313. The intermediate table 313 is movable in the XY directions with respect to the base 319 by a linear motor and a stage mechanism 317 including the linear motor.

  In this example, the outer shape of the fixed portion 304, the top plate 301, and the outer frame movable portion 306 is a square. Four side portions of the fixed portion 304 and the outer frame movable portion 306 are arranged along the X-axis and Y-axis directions.

  The four corners of the outer periphery of the fixed portion 304 and the four corners of the inner periphery of the outer frame movable portion 306 are connected by elastic support portions 302a, 302b, 302c, and 302d, respectively. The elastic support portions 302a, 302b, 302c, and 302d may be formed of any structure or material as long as the outer frame movable portion 306 can be elastically supported with respect to the fixed portion 304. The elastic support portions 302a, 302b, 302c, and 302d may be made of the same material as the fixed portion 304 or the outer frame movable portion 306, but may be made of a material different from those materials.

  The elastic support portions 302 a, 302 b, 302 c, and 302 d are disposed along the diagonal line of the fixed portion 304. An angle formed by the elastic support portions 302a, 302b, 302c, and 302d with the X axis is defined as θ. This angle θ is 45 degrees.

  Piezoelectric actuators 303a, 303b, 303c, and 303d are provided between the four outer edges of the fixed portion 304 and the four inner edges of the outer frame movable portion 306, respectively. The pair of X-axis piezoelectric actuators 303a and 303b are arranged on both sides of the fixed portion 304 along the X-axis direction and on the same straight line. Similarly, the pair of Y-axis piezoelectric actuators 303c and 303d are arranged on both sides of the fixed portion 304 along the Y-axis direction and on the same straight line.

  By extending one of the X-axis piezoelectric actuators 303 a and 303 b and contracting the other, the outer frame movable portion 306 and the top plate 301 move relative to the fixed portion 304 in the X direction.

  By extending one of the Y-axis piezoelectric actuators 303 c and 303 d and contracting the other, the outer frame movable unit 306 and the top plate 301 move relative to the fixed unit 304 in the Y direction.

  When the outer frame movable portion 306 moves relative to the fixed portion 304, the elastic support portions 302a, 302b, 302c, and 302d are elastically deformed. In this example, since the guidance in the X direction and the Y direction can be performed by the same elastic support portion, it is not necessary to provide separate guide mechanisms in the X direction and the Y direction, respectively.

  The structure of another example of the minute vibration removing mechanism according to the present invention will be described with reference to FIGS. 4A and 4B. 4A is a cross-sectional view showing a planar configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line AA in FIG. 4B. FIG. 4B is a diagram showing a cross-sectional configuration of the micro-vibration removing mechanism of this example viewed from the cutting line BB of FIG. 4A. As shown, the X axis and the Y axis are taken along the upper surface of the base 319, and the Z axis is taken vertically upward.

  Compared with the example described with reference to FIG. 3A and FIG. 3B, the minute vibration removing mechanism of this example has a rectangular outer shape in the fixed part 304, the top plate 301, and the outer frame movable part 306 in this example. Is different. The elastic support portions 302 a, 302 b, 302 c, and 302 d are disposed along the diagonal line of the fixed portion 304. An angle formed by the elastic support portions 302a, 302b, 302c, and 302d with the X axis is defined as θ. This angle θ is less than 45 degrees. Therefore, in this example, the displacement amount in the Y direction is larger than the displacement amount in the X direction of the outer frame movable portion 306. Therefore, the minute vibration removal mechanism of this example is suitable for a sample stage having a larger residual vibration amplitude in the Y direction than in the X direction. In this case, a desired amount of displacement can be realized without reducing the resonance frequency of the movable part more than necessary.

  The structure of still another example of the minute vibration removing mechanism according to the present invention will be described with reference to FIGS. 5A and 5B. FIG. 5A is a cross-sectional view showing a planar configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line AA in FIG. 5B. FIG. 5B is a diagram showing a cross-sectional configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line BB in FIG. 5A. As shown, the X axis and the Y axis are taken along the upper surface of the base 319, and the Z axis is taken vertically upward.

  The minute vibration removing mechanism of the present example includes a plate-like movable portion 314 and an outer frame fixing portion 316 disposed so as to surround the movable portion 314. A top plate 301 is mounted on the upper surface of the movable portion 314. The movable part 314 and the top plate 301 are movable with respect to the outer frame fixing part 316.

  The outer frame fixing part 316 is fixed on the intermediate table 313. The intermediate table 313 is movable in the XY directions with respect to the base 319 by a linear motor and a stage mechanism 317 including the linear motor.

  In this example, the outer shape of the outer frame fixing portion 316, the top plate 301, and the movable portion 314 is a square. Four side portions of the outer frame fixing portion 316 and the movable portion 314 are arranged along the X-axis and Y-axis directions.

  The four corners on the inner periphery of the outer frame fixing portion 316 and the four corners on the outer periphery of the movable portion 314 are connected by elastic support portions 302a, 302b, 302c, and 302d, respectively. The elastic support portions 302a, 302b, 302c, and 302d may be configured by any structure or material as long as the movable portion 314 can be elastically supported by the outer frame fixing portion 316.

  The elastic support portions 302 a, 302 b, 302 c, and 302 d are disposed along the diagonal line of the outer frame fixing portion 316. An angle formed by the elastic support portions 302a, 302b, 302c, and 302d with the X axis is defined as θ. This angle θ is 45 degrees.

  Piezoelectric actuators 303a, 303b, 303c, and 303d are provided between the four inner edges of the outer frame fixing portion 316 and the four outer edges of the movable portion 314, respectively. The pair of X-axis piezoelectric actuators 303a and 303b are arranged on both sides of the movable portion 314 along the X-axis direction and on the same straight line. Similarly, the pair of Y-axis piezoelectric actuators 303c and 303d are arranged on both sides of the movable portion 314 along the Y-axis direction and on the same straight line.

  By extending one of the X-axis piezoelectric actuators 303 a and 303 b and contracting the other, the movable portion 314 and the top plate 301 move relative to the outer frame fixing portion 316 in the X direction.

  By extending one of the Y-axis piezoelectric actuators 303c and 303d and contracting the other, the movable portion 314 and the top plate 301 move relative to the outer frame fixing portion 316 in the Y direction.

  When the movable portion 314 moves relative to the outer frame fixing portion 316, the elastic support portions 302a, 302b, 302c, and 302d are elastically deformed. In this example, since the guidance in the X direction and the Y direction can be performed by the same elastic support portion, it is not necessary to provide separate guide mechanisms in the X direction and the Y direction, respectively.

  In the minute vibration removing mechanism of this example, the movable portion is positioned with respect to the fixed portion using the elastic support portion and the piezoelectric actuator. In this case, various forms can be considered for the arrangement of the elastic support portion and the piezoelectric actuator. Here, the elastic support portions are arranged symmetrically on both sides of the center line of the top table in the Y-axis direction. When a swing around the Y axis, that is, a force in the pitching direction is applied to the top table, the moment stiffness M around the Y axis is expressed by the following equation.

M = N × K × L Equation 1
Here, K is the rigidity of the elastic support portion in the Z direction, and N is the number of elastic support portions. L is the distance in the X direction between the center of rotation and the elastic support portion.

  Hereinafter, calculation examples of the moment stiffness M around the Y axis will be described with reference to some examples of the minute vibration removal mechanism. In these examples, a total of four piezoelectric actuators are provided, two on each side along the X-axis direction and two on both sides along the Y-axis direction.

  FIG. 6A shows an example of a minute vibration removing mechanism. The micro-vibration removing mechanism of this example includes a central square fixed portion 414, a surrounding inner frame movable portion 415, and a surrounding outer frame movable portion 416. Although the top table 411 (FIG. 6B) is attached to the outer frame movable portion 416, the top table 411 is not shown in FIG. 6A. The fixed portion 414 and the inner frame movable portion 415 are connected by Y-axis elastic support portions 412c and 412d at the four corners. By the Y-axis elastic support portions 412c and 412d, the inner frame movable portion 415 is allowed to move in the Y-axis direction with respect to the fixed portion 414.

  The inner frame movable portion 415 and the outer frame movable portion 416 are connected by X-axis elastic support portions 412a and 412b at the four corners. The X-axis elastic support portions 412a and 412b allow the outer frame movable portion 416 to move in the X-axis direction with respect to the inner frame movable portion 415.

  A pair of X-axis piezoelectric actuators 413a and 413b are mounted between the inner frame movable unit 415 and the outer frame movable unit 416 along the X-axis direction. The X-axis piezoelectric actuators 413a and 413b are arranged along the same straight line on both sides of the fixed portion 414. Similarly, a pair of Y-axis piezoelectric actuators are mounted between the fixed portion 414 and the inner frame movable portion 415 along the Y-axis direction.

  With reference to FIG. 6B, the moment stiffness of the minute vibration removal mechanism of FIG. 6A will be considered. FIG. 6B is a diagram schematically showing a cross-sectional structure of the example of the minute vibration removing mechanism shown in FIG. 6A. Inner frame movable portions 415 are disposed on both sides of the fixed portion 414, and outer frame movable portions 416 are disposed on both sides thereof. Two Y-axis elastic support portions 412c and 412d are provided between the fixed portion 414 and the inner frame movable portion 415, respectively. Two X-axis elastic support portions 412a and 412b and one piezoelectric actuator 413a and 413b are provided between the inner frame movable portion 415 and the outer frame movable portion 416, respectively.

  Here, the rigidity in the Z direction of each of the X-axis elastic support portions 412a and 412b and the Y-axis elastic support portions 412c and 412d is assumed to be K, and the rigidity in the Z direction of each of the piezoelectric actuators 413a and 413b is assumed to be Kp. Furthermore, the width of the inner frame movable portion 415 (the dimension in the X-axis direction in FIG. 6B) is sufficiently small. That is, the Y-axis elastic support portion 412c, the X-axis elastic support portion 412a, and the piezoelectric actuator 413a are considered to be arranged in a straight line along the Y-axis direction. When a force in the pitching direction around the Y axis is applied to the top table 411, the moment rigidity M1 of the minute vibration removing mechanism is obtained by the following equation.

M1 = {2K (2K + Kp) × L} / (4K + Kp) Equation 2
Here, K is the rigidity of the elastic support portion in the Z direction, and Kp is the rigidity of the piezoelectric actuator in the Z direction. L is a distance in the X direction between the elastic support portions 412a and 412b on both sides.

  Here, it is assumed that the width of the inner frame movable portion 415 (the dimension in the X-axis direction in FIG. 6B) is sufficiently small, but it is not actually zero. Accordingly, the length of the moment foot of the Y-axis elastic support portions 412c and 412d between the fixed portion 414 and the inner frame movable portion 415 is smaller than L / 2. Therefore, the actual value of the moment rigidity M1 is smaller than the value obtained by the above-described equation 2.

  FIG. 7A shows another example of the minute vibration removing mechanism. The micro-vibration removing mechanism of this example includes a center square fixed portion 424 and an outer frame movable portion 426 around the center fixed portion 424. Although the top table 421 (FIG. 7B) is attached to the outer frame movable portion 426, the top table 421 is not shown in FIG. 7A.

  An elastic support portion and a piezoelectric actuator are provided between the four outer portions of the fixed portion 424 and the four inner portions of the outer frame movable portion 426, respectively. The pair of X-axis elastic support portions 422a and 422b are disposed on both sides of the fixed portion 424 along the X-axis direction and on the same straight line. The pair of X-axis piezoelectric actuators 423a and 423b are arranged on both sides of the fixed portion 424 along the X-axis direction and on the same straight line.

  Similarly, the pair of Y-axis elastic support portions and the pair of Y-axis piezoelectric actuators are disposed on both sides of the fixed portion 424 along the Y-axis direction and on the same straight line.

  With reference to FIG. 7B, the moment stiffness of the minute vibration removal mechanism of FIG. 7A will be considered. FIG. 7B is a diagram schematically showing a cross-sectional structure of the example of the minute vibration removing mechanism shown in FIG. 7A. Outer frame movable portions 426 are disposed on both sides of the fixed portion 424. Between the fixed portion 424 and the outer frame movable portion 426, Y-axis elastic support portions 422a and 422b and piezoelectric actuators 423a and 423b are provided, respectively.

  Here, the rigidity in the Z direction of each of the Y-axis elastic support portions 422a and 422b is all K, and the rigidity in the Z direction of each of the piezoelectric actuators 423a and 423b is all Kp. Furthermore, the dimensions of the piezoelectric actuators 423a and 423b are sufficiently small. When a force in the pitching direction around the Y axis is applied to the top table 421, the moment rigidity M2 of the minute vibration removing mechanism is obtained by the following equation.

M2 = KL / (1 + K / Kp) Equation 3
Here, K is the rigidity of the elastic support portion in the Z direction, and Kp is the rigidity of the piezoelectric actuator in the Z direction. L is a distance in the X direction between the elastic support portions 422a and 422b on both sides.

  Here, it is assumed that the dimensions of the piezoelectric actuators 423a and 423b are sufficiently small, but they are not actually zero. Therefore, the actual value of the moment stiffness M2 is smaller than the value obtained by the above-described equation 3.

  FIG. 8A shows an outline of an example of the minute vibration removing mechanism shown in FIG. 3A. The minute vibration removing mechanism of the present example includes a central square fixed portion 434 and a surrounding outer frame movable portion 436. Although the top table 431 (FIG. 8B) is attached to the outer frame movable portion 436, the top table 431 is not shown in FIG. 8A. The fixed portion 434 and the outer frame movable portion 436 are connected by elastic support portions 432a, 432b, 432c, and 432d at four corners. The elastic support portions 432 a, 432 b, 432 c, and 432 d are disposed along the diagonal line of the fixed portion 434.

  The elastic support portions 432a, 432b, 432c, and 432d allow the outer frame movable portion 436 to move in the X-axis direction and the Y-axis direction with respect to the fixed portion 434.

  Between the fixed portion 434 and the outer frame movable portion 436, a pair of X-axis piezoelectric actuators 433a and 433b are mounted along the X-axis direction. The X-axis piezoelectric actuators 433a and 433b are arranged along the same straight line on both sides of the fixed portion 434. Similarly, a pair of Y-axis piezoelectric actuators are mounted between the fixed portion 434 and the outer frame movable portion 436 along the Y-axis direction.

  With reference to FIG. 8B, the moment stiffness of the minute vibration removal mechanism of FIG. 8A will be considered. FIG. 8B is a diagram schematically showing a cross-sectional structure of the example of the minute vibration removing mechanism shown in FIG. 8A. Outer frame movable parts 436 are arranged on both sides of the fixed part 434. Two elastic support portions 432a and 432b and one piezoelectric actuator 433a and 433b are provided between the fixed portion 434 and the outer frame movable portion 436, respectively.

  Here, the rigidity of each of the elastic support portions 432a, 432b, 432c, and 432d in the Z direction is all K, and the rigidity of each of the piezoelectric actuators 433a and 433b is all Kp. Furthermore, the dimensions of the piezoelectric actuators 423a and 423b are sufficiently small. When a force in the pitching direction around the Y axis is applied to the top table 431, the moment rigidity M2 of the minute vibration removing mechanism is obtained by the following equation.

M3 = (4K × L / 2) + (2Kp × L / 2) = (2K + Kp) L Equation 4
Here, K is the rigidity of the elastic support portion in the Z direction, and Kp is the rigidity of the piezoelectric actuator in the Z direction. L is a distance in the X direction between the elastic support portions 432a and 432b on both sides.

Therefore, the moment stiffnesses M1, M2, and M3 of the minute vibration eliminating mechanism shown in FIGS. 6A, 7A, and 8A are compared as follows.
M3>M1> M2

  Comparing the minute vibration removal mechanism of FIG. 8A and the example of FIG. 6A, in this example, since the inner frame movable part is not provided, the number of elastic support parts is small. Therefore, in the case of the minute vibration removing mechanism shown in FIG. 8A, the amount of elastic deformation can be reduced.

  Comparing the minute vibration removal mechanism of FIG. 8A and the example of FIG. 7A, in this example, even if the piezoelectric actuator is elastically deformed, the amount of deformation in the pitching direction of the outer frame movable portion does not increase. Furthermore, in this example, since the piezoelectric actuator and the elastic support portions 432a and 432b are arranged in parallel, the distance between the opposing elastic support portions can be increased with respect to the size of the top table. Thereby, in this example, it is possible to increase the moment rigidity in the pitching direction while driving and guiding the outer frame movable portion in the horizontal direction.

FIG. 9A shows the relationship between the applied voltage and displacement of the piezoelectric actuator. In FIG. 9A, the horizontal axis represents the voltage applied to the piezoelectric actuator, and the vertical axis represents the displacement. As shown in the figure, the piezoelectric actuator has a characteristic that the dimension expands as the applied voltage increases, but the relationship between the applied voltage and the displacement is not completely linear but nonlinear. That is, the curve when the applied voltage of the piezoelectric actuator is increased to increase the total length of the piezoelectric actuator is different from the curve when the applied voltage is decreased to shorten the total length, and has a hysteresis characteristic. When the displacement of the piezoelectric actuator increases, the sensitivity to changes in the applied voltage is higher than when the displacement of the piezoelectric actuator decreases. That is, the sensitivity to the applied voltage is higher when the piezoelectric actuator is extended than when the piezoelectric actuator is contracted.

  Generally, when a negative applied voltage is applied to the piezoelectric actuator, the piezoelectric actuator may be damaged. Therefore, in order to prevent a negative voltage from being applied to the piezoelectric actuator, for example, a bias voltage of about +10 V is applied. This bias voltage is set as a reference voltage V0. The reference position of the piezoelectric actuator at this time is L0. For example, if an applied voltage is added in a range of ± 10 V with respect to the reference voltage V0, the applied voltage range becomes a positive range of 0 to 20 V, and damage to the piezoelectric actuator can be prevented. In the following description, the applied voltage being positive or negative means positive or negative with respect to the reference voltage V0, and no negative voltage is applied to the piezoelectric actuator.

  FIG. 9B shows an example of a stepped voltage applied to the piezoelectric actuator. FIG. 9C shows the displacement of the piezoelectric actuator. In this example, from time 0 to Ta, the applied voltage is V = V1 (> 0), and the displacement of the piezoelectric actuator is L1 (where L1 <L0). From time Ta to Tb, the applied voltage is V = V2 (where V2> V1), and the displacement of the piezoelectric actuator is L2. When the time Tb is passed, the applied voltage becomes V = V1, and the displacement of the piezoelectric actuator becomes L1. As described above, since the sensitivity of the piezoelectric actuator when the applied voltage is increased is relatively high, an overshoot occurs at time Ta. On the other hand, since the sensitivity of the piezoelectric actuator when the applied voltage is decreased is relatively low, the displacement of the piezoelectric actuator does not instantaneously return to the original value at time Tb.

  In general, in a control system using a single piezoelectric actuator, since the piezoelectric actuator has a hysteresis characteristic, it is necessary to use parameters of the control system corresponding to both characteristics when the voltage is increased and when the voltage is decreased. In this case, it is necessary to reduce the frequency band of the control system as compared with the case where driving is performed using an optimum parameter for a single characteristic. As described above, in the control system using a single piezoelectric actuator, the hysteresis characteristic exists, so that the control characteristic is deteriorated.

  On the other hand, according to the present invention, a pair of piezoelectric actuators is used for each of the driving directions of the X direction and the Y direction. Further, the pair of piezoelectric actuators are arranged to face each other, and apply applied voltages having positive and negative signs opposite to each other. Accordingly, the pair of piezoelectric actuators are displaced in directions opposite to each other. Thereby, it is possible to avoid the deterioration of the control characteristics due to the hysteresis characteristics of the piezoelectric actuator.

  With reference to FIGS. 10A, 10B, 10C, 10D, and 10E, the operation of the piezoelectric actuator in the minute vibration removing mechanism of the present invention will be described. For example, consider a case in which the outer frame movable unit 306 is displaced in the positive direction of the X axis in the minute vibration removal mechanism of FIG. As shown in FIG. 10A, the applied voltage of the first X-axis piezoelectric actuator 303a is decreased to contract the entire length. At the same time, as shown in FIG. 10B, the applied voltage of the second X-axis piezoelectric actuator 303b is increased to extend the entire length. Accordingly, the outer frame movable unit 306 moves in the positive direction of the X axis. In this example, when the outer frame movable unit 306 moves, it is possible to avoid deterioration of the control characteristics due to the hysteresis characteristics of the piezoelectric actuator. Here, an example of displacement of the piezoelectric actuator when a stepped voltage is applied to the piezoelectric actuator will be described.

  FIG. 10C shows the time change of the applied voltage Va of the first X-axis piezoelectric actuator 303a. From time 0 to Ta, the applied voltage is Va = V2, but at time Ta, the applied voltage is decreased to Va = V1 (where V2> V1> 0). From time Ta to Tb, the applied voltage is Va = V1 (where V1> 0), but at time Tb, the applied voltage is increased to Va = V2. FIG. 10D shows the time change of the applied voltage Vb of the second X-axis piezoelectric actuator 303b. From time 0 to Ta, the applied voltage is Vb = V1, but at time Ta, the applied voltage is increased to Vb = V2 (where V2> V1> 0). From time Ta to Tb, the applied voltage is Vb = V2, but at time Tb, the applied voltage is decreased to Vb = V1.

  FIG. 10E shows the change over time of the displacement of the outer frame movable unit 306 in the X-axis direction. From time 0 to Ta, the first X-axis piezoelectric actuator 303a is in an expanded state, and the second X-axis piezoelectric actuator 303b is in a contracted state. Therefore, the outer frame movable unit 306 is disposed at the displacement L1 in the negative direction of the X axis from the reference position L0.

  At time Ta, the first X-axis piezoelectric actuator 303a contracts, and at the same time, the second X-axis piezoelectric actuator 303b expands. Even if the contraction operation of the first X-axis piezoelectric actuator 303a is slow, the extension operation of the second X-axis piezoelectric actuator 303b is rapid. Accordingly, the outer frame movable portion 306 quickly moves to the displacement L2 at time Ta.

  From time Ta to Tb, the first X-axis piezoelectric actuator 303a is in a contracted state, and the second X-axis piezoelectric actuator 303b is in an expanded state. Therefore, the outer frame movable unit 306 is disposed at a displacement L2 in the positive direction of the X axis from the reference position L0.

  At time Tb, the first X-axis piezoelectric actuator 303a expands, and at the same time, the second X-axis piezoelectric actuator 303b contracts. Even if the contraction operation of the second X-axis piezoelectric actuator 303b is slow, the extension operation of the first X-axis piezoelectric actuator 303a is rapid. Accordingly, the outer frame movable portion 306 quickly moves to the displacement L1 at time Tb.

  According to this example, since the pair of piezoelectric actuators are driven in opposite directions regardless of whether the outer frame movable unit 306 moves in the positive direction or the negative direction of the X axis, the influence of the hysteresis characteristics Cancel each other. Therefore, the outer frame movable unit 306 can be driven quickly.

  FIG. 11 shows a block diagram of a control system of the minute vibration removing mechanism of the present invention. The transfer function 704 of the control system of the minute vibration removal mechanism is Cp, the transfer function 703 of the mechanism system of the minute vibration removal mechanism is Pp, the transfer function 702 of the stage control system is Cs, the transfer function 701 of the stage mechanism system is Ps, The reverse characteristic 705 of the mechanism system of the minute vibration removing mechanism is defined as Pp ′. The difference between the position command value Xref and the measured value X of the top table position is input to the controller Cp, and the output of the controller Cp is input to the mechanism Pp, so that the minute vibration removing mechanism operates. Further, by subtracting the inverse characteristic Pp ′ of the minute vibration removal mechanism obtained from the output of the controller Cp from the input to the stage control system Cs, the control system of the stage and the minute vibration removal mechanism interfere with each other. To prevent.

  However, in order to prevent interference in this way, it is necessary that the minute vibration removing mechanism has a sufficiently high response to the stage. In this way, by coordinating the minute vibration removing mechanism with the stage control system, the tracking operation is performed with respect to the displacement of the top table so that the average applied voltage of the piezoelectric actuator becomes the value of the bias voltage. Therefore, it is possible to prevent the position of the top table from exceeding the movable stroke of the minute vibration removing mechanism due to low frequency and large amplitude vibration such as drift.

  FIG. 12 shows the relationship between the length measurement sequence and the vibration of the top table of the stage when the minute vibration removal mechanism is mounted on the positioning stage of the length measurement SEM. In the first step S101, the stage (intermediate table) is moved to the measuring point on the order of several tens of millimeters by the stage mechanism. In the second step S102, addressing to the measuring point is performed. In the third step 103, autofocus to high magnification is performed. In the fourth step 104, image acquisition at a high magnification is performed. The minute vibration removal mechanism of this example suppresses minute residual vibration 801 on the order of nanometers when image acquisition at a high magnification is performed. That is, the control of the minute vibration removing mechanism operates in the range of image acquisition at a high magnification of the length measurement sequence. However, even in other length measurement sequences, by removing minute vibrations using the control system of FIG. 11, if the stage deviation is within the movable stroke of the minute vibration removing mechanism, the vibration of the top table can be suppressed.

  FIG. 13 shows a schematic view of another embodiment of the minute vibration removing mechanism. FIG. 13 shows an example of a structure in which the inner side is a movable part and the outer side is a fixed frame, as in FIGS. 5A and 5B. In order to show the internal structure, a perspective view is shown, and hidden lines are shown by dotted lines. A rod 903 is disposed between the piezoelectric actuator 903 and the movable portion 901, and the pressing force of the piezoelectric actuator 903 is transmitted to the movable portion 901 via the rod 903. Further, the piezoelectric actuator 904 is fixed to the outer frame fixing portion 902 using a clasp 905.

  FIG. 14 shows an example of the structure of the piezoelectric actuator mounting portion. The piezoelectric actuator 911 is stored in a piezo storage hole 912 provided on the outer four surfaces of the outer frame fixing portion 913. With this attachment structure, the piezoelectric actuator and the rod can be disposed so as to surround the movable portion 915 in four directions in the X direction and the Y direction without dividing the outer frame fixing portion into four. Thereby, the rigidity fall of the outer frame fixing | fixed part by using a rod can be suppressed.

  With reference to FIGS. 15A and 15B, the structure of the minute vibration removing mechanism when the rod described in FIG. 13 is used will be described. FIG. 15A is a cross-sectional view showing a planar configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line AA in FIG. 15B. FIG. 15B is a diagram showing a cross-sectional configuration of the micro-vibration removing mechanism of this example viewed from the cutting line BB in FIG. 15A. As shown in the drawing, the X axis and the Y axis are taken along the upper surface of the base 929, and the Z axis is taken vertically upward.

  The minute vibration removing mechanism of this example includes a plate-like movable portion 926 and an outer frame fixing portion 925 arranged so as to surround it. A top plate 921 is mounted on the upper surface of the movable portion 926. The movable portion 926 and the top plate 921 are movable with respect to the outer frame fixing portion 925.

  The outer frame fixing portion 925 is fixed on the intermediate table 928. The intermediate table 928 is movable in the XY direction with respect to the base 929 by a stage mechanism 930 including a linear motor and a linear motor.

  In this example, the outer shape of the outer frame fixing portion 925, the top plate 921, and the movable portion 926 is a square. Four side portions of the outer frame fixing portion 925 and the movable portion 926 are arranged along the X-axis and Y-axis directions.

  The four inner corners of the outer frame fixing portion 925 and the four outer corners of the movable portion 926 are connected by elastic support portions 922a, 922b, 922c, and 922d, respectively. The elastic support portions 922a, 922b, 922c, and 922d may be formed of any structure or material as long as the movable portion 926 can be elastically supported with respect to the outer frame fixing portion 925.

  The elastic support portions 922 a, 922 b, 922 c, and 922 d are disposed along the diagonal line of the outer frame fixing portion 925. The angle formed by the elastic support portions 922a, 922b, 922c, 922d and the X axis is θ. This angle θ is 45 degrees.

  Piezoelectric actuators 923a, 923b, 923c, and 923d and rods 924a, 924b, 924c, and 924d are provided between the four inner edges of the outer frame fixing portion 925 and the four outer edges of the movable portion 926, respectively. The rod 924a is in contact with the piezoelectric actuator 923a, the rod 924b is in contact with the piezoelectric actuator 923b, the rod 924c is in contact with the piezoelectric actuator 923c, and the rod 924d is in contact with the piezoelectric actuator 923d. Each rod 924a, 924b, 924c, 924d is arranged so as to surround the movable portion 926.

  The pair of X-axis piezoelectric actuators 923a and 923b and the rods 924a and 924b are arranged on both sides of the movable portion 926 along the X-axis direction and on the same straight line. Similarly, the pair of Y-axis piezoelectric actuators 923c and 923d and the rods 924c and 924d are disposed on both sides of the movable portion 926 along the Y-axis direction and on the same straight line.

  By extending one of the X-axis piezoelectric actuators 923 a and 923 b and contracting the other, the movable portion 926 and the top plate 921 move in the X direction relative to the outer frame fixing portion 925.

  By extending one of the Y-axis piezoelectric actuators 923c and 923d and contracting the other, the movable portion 926 and the top plate 921 move relative to the outer frame fixing portion 925 in the Y direction.

  When the movable portion 926 moves relative to the outer frame fixing portion 925, the elastic support portions 922a, 922b, 922c, and 922d are elastically deformed. In this example, since the guidance in the X direction and the Y direction can be performed by the same elastic support portion, it is not necessary to provide separate guide mechanisms in the X direction and the Y direction, respectively.

  The arrangement of the piezoelectric actuators 923a, 923b, 923c, 923d and the rods 924a, 924b, 924c, 924d can be interchanged, and the rods can be arranged on both sides of the piezoelectric actuators 923a, 923b, 923c, 923d. . However, since it is necessary to connect wiring for applying a driving voltage to the piezoelectric actuators 923a, 923b, 923c, and 923d, the piezoelectric actuators 923a, 923b, 923c, and 923d are connected to the rods as shown in FIGS. 15A and 15B. It is desirable to dispose outside of 924a, 924b, 924c, and 924d.

  An example in which a rod is not used in the same shape as in FIGS. 15A and 15B will be described with reference to FIGS. 16A and 16B. FIG. 16A is a cross-sectional view showing a planar configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line AA in FIG. 16B. FIG. 16B is a diagram showing a cross-sectional configuration of the micro-vibration removing mechanism of this example as viewed from the cutting line BB in FIG. 16A. As shown in the drawing, the X axis and the Y axis are taken along the upper surface of the base 929, and the Z axis is taken vertically upward.

  Compared with the example described with reference to FIG. 15A and FIG. 15B, the minute vibration removal mechanism of this example has piezoelectric actuators 923 a, 923 b, 923 c between the outer frame fixing part 925 and the movable part 926 in this example. The only difference is that there is only 923d and no rod is arranged. However, the shapes of the upper surfaces of the outer frame fixing portion 925 and the movable portion 926 are the same as those in the example of FIGS. 15A and 15B.

  17A shows a state of deformation when the movable portion 926 of the minute vibration removing mechanism using the rod of FIGS. 17A, 15A, and 15B is displaced by the same amount. FIG. 17B shows a state of deformation when the movable portion 926 of the minute vibration removal mechanism that does not use the rod of FIGS. 16A and 16B is displaced. In FIG. 17A, the piezoelectric actuator 923a contracts and the piezoelectric actuator 923b expands, and a force is applied to the movable portion 926 via the rods 924a and 924b to apply displacement in the X direction. In FIG. 17B, the piezoelectric actuator 923a contracts and the piezoelectric actuator 923b expands, and a force is applied to the movable portion 926 to apply displacement in the X direction. In FIG. 17A, rods 924c and 924d parallel to the Y direction exist and undergo shear deformation, so that the shear deformation of the piezoelectric actuators 923a and 923b is suppressed to be smaller than that of the piezoelectric actuator 923c of FIG. 17B. That is, in FIG. 17B, shear stress is directly applied to the piezoelectric actuators 923c and 923d, but in FIG. 17A, shear stress applied to the piezoelectric actuators 923c and 923d is suppressed. As the piezoelectric actuator, an actuator in which piezoelectric ceramics are laminated is generally used, and since the piezoelectric ceramics are fixed by an adhesive, it is weak against a shear load. That is, by adopting a structure in which a shear load is released using a rod as shown in FIG. 17A, an effect of preventing breakage of the piezoelectric actuator can be expected. If a limit value is set for the shear stress applied to the piezoelectric actuator, the micro-vibration removing mechanism using the rod in FIG. 17A is more effective for expanding the stroke of the movable portion 926.

  Since the maximum stroke expansion of the movable part described above makes it possible to correct the stage drift to some extent even with only the minute vibration removal mechanism, when acquiring an image at a high magnification in the control sequence of FIG. The thrust of the moving actuator can be cut off, and the table can be positioned only by the minute vibration removing mechanism. As a result, it is possible to eliminate the minute vibration disturbance generated from the coarse movement actuator after positioning, and the stop accuracy can be further improved.

FIG. 18A shows the relationship between the length of the rod, the length of the piezoelectric actuator, and the displacement of the movable part. Here, since the displacement of the movable part is less than the stroke of the piezoelectric actuator, considering the fact that the displacement is sufficiently small, the deformation that occurs in the rod and piezo can only be considered as shear deformation, and bending deformation can be ignored. And If the displacement of the movable part is Δx, the strain of the piezoelectric actuator is γp, and the strain of the rod is γr, the displacement Δx of the movable part is obtained using the length Lp of the piezoelectric actuator and the length Lr of the rod.
Δx = γr × Lr + γp × Lp Equation 5
It is expressed. Also, assuming that the shear stress applied to the piezoelectric actuator is τp and the shear stress applied to the rod is τr, using the shear stiffness Gp of the piezoelectric actuator and the shear stiffness Gr of the rod, τp and τr are respectively
τp = Gp × γp Equation 6
τr = Gr × γr Equation 7
It is expressed. Furthermore, from the balance of the shearing force of the rod and the piezoelectric actuator,
τr × Ar = τp × Ap Equation 8
Therefore, substituting Equation 5, Equation 6, and Equation 7 into Equation 8 to eliminate τr, γp, γr, Δx = (between the displacement Δx of the movable part and the shear stress τp applied to the piezoelectric actuator) Lr / Gr × Ap / Ar + Lp / Gp) × τp Equation 9
Such a relationship is derived.

Here, the maximum stroke of the movable part of the minute vibration removing mechanism was calculated when the length Lp of the piezoelectric actuator was 20 mm and the shear rigidity of the piezoelectric actuator was 115 N / μm. The piezoelectric actuator was assumed to have a structure in which a piezoelectric ceramic having a diameter of about 5.5 mm was covered with a stainless steel case having a diameter of 20 mm and a thickness of 0.3 mm. The strength in the shearing direction of the piezoelectric actuator is 0.25 N / mm ^ 2 as a value obtained by dividing the peeling shear stress of the adhesive 5 N / mm ^ 2 by a safety factor 20 in consideration of the repeated load. Assumed. From the above conditions, when the shear stress that can be repeatedly applied to the piezoelectric actuator is τpc, the maximum value of the displacement Δx of the movable part, that is, the maximum stroke Δxc of the movable part is
Δxc = (Lr / Gr × Ap / Ar + Lp / Gp) × τpc Equation 10
It is expressed.

  FIG. 18B shows a change in the value of the maximum stroke Δxc of the movable part when the rod length Lr is changed. When the rod length Lr is 0 mm, that is, when the rod is not used, the maximum stroke of the movable part is 20 nm or less, whereas the maximum stroke of the movable part is about 70 nm by setting the rod length Lr to 80 mm, for example. It is possible to extend to the extent. Further, since the inclination of this graph increases by reducing the shear rigidity of the rod, the maximum stroke of the movable part can be further increased by using a rod having a small shear rigidity. However, if the longitudinal rigidity of the rod decreases, the displacement of the piezoelectric actuator is absorbed by the rod and cannot be transmitted to the movable part, or the natural frequency of the rod may decrease and resonance may occur. It is desirable not to reduce the stiffness.

  FIG. 19 shows an example of a structure that reduces the shear rigidity by devising the shape of the rod. An enlarged view of the enlarged view of the rod 931 is shown in FIG. The columnar rod 933 has, for example, a solid shape such as a columnar shape or a prismatic shape. By changing the shape of this columnar rod 933 into a shape like a rod 934 having a parallel spring structure in which plate-like structures parallel to the Y direction are stacked, shearing in the X direction is performed without reducing the rigidity in the Y direction. It is possible to reduce the directional stiffness. However, the columnar rod 933 and the parallel spring structure rod 934 have the same cross-sectional area in a plane perpendicular to the Y direction. Thereby, since the value of Gr in Expression 10 can be reduced, the slope of the graph in FIG. 18B can be increased. That is, by increasing the length of the rod, it is expected that the effect of increasing the maximum stroke of the movable part is increased.

  Similar to changing the shape of the rod, the same effect can be obtained by changing the material constituting the rod to reduce the shear rigidity Gr. That is, it is effective to use a material having an anisotropic Young's modulus for the rod material. Examples of the material include a rolled material such as stainless steel for springs, and FRP containing fibers inside. For these materials with anisotropic Young's modulus, the rod should be manufactured so that the direction in which the Young's modulus is large is the direction in which the compressive force from the piezoelectric actuator is applied, and the direction in which the Young's modulus is small is the direction in which the movable part is displaced. For example, it is possible to suppress the shear load of the piezoelectric actuator and improve the stroke of the movable part.

  FIG. 20 shows an example of a minute vibration removal mechanism in which a notch is provided in the movable portion 926 to increase the length of the rods 924a, 924b, 924c, and 924d. In the structure shown in FIGS. 15A and 15B, the length of the rods 924a, 924b, 924c, and 924d can be increased by reducing the area of the upper surface of the movable portion 926, but on the upper surface of the movable portion 926. If the area is reduced, the distances between the elastic support portions 922a, 922b, 923c, and 924d are reduced, and the moment rigidity may be reduced. Therefore, as shown in FIG. 20, by providing a notch or hole of a size that allows the rod to enter the movable part, the rods 924a, 924b, 924b, 924a, 924b, while maintaining the distance between the elastic support parts 922a, 922b, 923c, 924d It is possible to increase the length of 924c and 924d. That is, it is possible to suppress shear stress applied to the piezoelectric actuators 923a, 923b, 923c, and 923d when the movable portion 926 is displaced while maintaining the moment rigidity.

  FIG. 21 shows an example of a minute vibration removal mechanism that increases the number of piezoelectric actuators and rods in one direction and enables control in the rotational direction. In FIG. 21, a piezoelectric actuator 923e is added next to the piezoelectric actuator 923b that gives a pressing force in the + X direction, and a rod 924e parallel to the rod 924b is added. By extending the piezoelectric actuator 923e relative to the piezoelectric actuator 923b, a rotational force can be applied to the movable portion 926 in the clockwise direction around the Z axis, and the yawing direction can be controlled.

  FIG. 22 shows an example of the configuration of a minute vibration removing mechanism in which a piezoelectric actuator 944f, a clasp 945f, and a rod 943f are arranged below the movable portion 901 in a direction perpendicular to the Z direction. The movable portion 901 can be displaced in the Z direction by expanding and contracting the Z direction piezoelectric actuator 944f. The movable part 901 is supported by an elastic support part 946. When the movable part 901 is displaced in the X direction and the Y direction, the shear stress applied to the piezoelectric actuator 944f is suppressed by the rod 943f, and when the movable part 901 is displaced in the Z direction, the rod 943a applies the piezoelectric actuator 944a. Shear stress is suppressed.

  Although the examples of the present invention have been described above, the present invention is not limited to the above-described examples, and it is easy for those skilled in the art to make various modifications within the scope of the invention described in the claims. Will be understood.

11 Lens barrel 12 Vacuum chamber 101 Top table 102 Micro vibration removal mechanism 102a Piezoelectric actuator 102b Fixing member 103 Intermediate table (stage)
107 Stage mechanism 110 Sample 111 Flat mirror 112 Laser interferometer 113 Control unit 201 Top table 202 Micro vibration elimination mechanism 203 Intermediate table 205 Base 206 X-axis intermediate slider 206a Y-axis linear guide rail 206b Y-axis linear guide movable part 208 Y Intermediate axis slider 208a X-axis linear guide rail 208b X-axis linear guide movable part 208c X-axis linear guide rail 208d X-axis linear guide movable part 208e X-axis linear motor 209a Y-axis linear guide rail 209b Y-axis linear guide Movable portion 209e Y-axis linear motor 210 Wafer 211a X-axis plane mirror 211b Y-axis plane mirror 212a X-axis laser interferometer 212b Y-axis laser interferometer 301 Top tables 302a, 302b, 302c, 02d Elastic support parts 303a, 303b X-axis piezoelectric actuators 303c, 303d Y-axis piezoelectric actuators 304 Fixed part 306 Outer frame movable part 313 Intermediate table 314 Movable part 316 Outer frame fixed part 317 Stage mechanism 319 Base 411 Top table 412a, 412b X axis Elastic support portions 412c, 412d Y-axis elastic support portions 413a, 413b Piezoelectric actuator 414 Fixed portion 415 Inner frame movable portion 416 Outer frame movable portion 421 Top table 422a, 422b Elastic support portions 423a, 423b Piezoelectric actuator 424 Fixed portion 426 Outer frame movable Section 431 Top table 432a, 432b, 432c, 432d Elastic support section 433a, 433b Piezoelectric actuator 434 Fixed section 436 Outer frame movable section 701 Transfer function 702 of stage mechanism system Transfer function 703 of the control system of the stage Transfer function 704 of the mechanism system of the minute vibration elimination mechanism Control function transfer function 705 of the minute vibration elimination mechanism Inverse characteristics 801 of the minor vibration removal mechanism 901 Minute residual vibration 901 Inner movable part 902 Outside Frame movable portion 903 Rod 904 Piezoelectric actuator 905 Clasp 906 Elastic support portion 911 Piezoelectric actuator 912 Piezo storage hole portion 913 Outer frame fixing portion 914 Clasp 915 Movable portion 921 Top plates 922a, 922b, 923c, 924d Elastic support portions 923a, 923b , 923c, 923d Piezoelectric actuators 924a, 924b, 924c, 924d Rod 925 Outer frame fixing part 926 Movable parts 927a, 927b, 927c, 927d Clasp 928 Intermediate table 929 Base 930 Stage mechanism 923e Additional piezoelectric element Rod 934e additional rods 941 movable portion 942 outer frame fixing portion of Chueta 931 rod 932 enlarged view 933 columnar rod 934 parallel spring structure 943a, 943f rods 944a, 944f piezoelectric actuator 945a, 945f clasp 946 elastically supporting portion

Claims (25)

An X-axis and a Y-axis provided along a horizontal plane, a top table for holding a sample to be observed, an intermediate table disposed below the top table, and the intermediate table in the X-axis direction and the Y-axis In a sample stage device having a stage mechanism for positioning a sample by moving along a direction,
Between the top table and the intermediate table, a minute vibration removing mechanism for removing minute vibrations of the top table is provided,
The minute vibration removing mechanism includes a movable part attached to the top table, a fixed part attached to the intermediate table, an elastic support part for elastically supporting the movable part with respect to the fixed part, A piezoelectric actuator that drives the movable part with respect to the fixed part,
The elastic support portion is arranged to connect the four corners of the fixed portion and the four corners of the movable portion,
The piezoelectric actuators are arranged along the same straight line on both sides in the X-axis direction of the fixed part, and are identical on both sides in the Y-axis direction of the fixed part and a pair of X-axis piezoelectric actuators that expand and contract in opposite directions. A sample stage apparatus comprising: a pair of Y-axis piezoelectric actuators arranged along a straight line and extending and contracting in opposite directions. The sample stage apparatus according to claim 1, wherein
The sample stage apparatus, wherein the elastic support portion is disposed along a diagonal line of the fixed portion so as to connect the four corners of the fixed portion and the four corners of the movable portion. The sample stage apparatus according to claim 1, wherein
The sample stage device, wherein the fixed part is formed in a rectangular shape, and the movable part is formed as a frame member surrounding the fixed part. The sample stage apparatus according to claim 1, wherein
A sample stage apparatus, wherein a positive bias voltage is applied to the piezoelectric actuator in advance so that a negative voltage is not applied. The sample stage apparatus according to claim 1, wherein
The intermediate table is driven with a stroke of several hundred millimeters by the stage mechanism, and the top table is driven with a stroke of several tens of nanometers by a piezoelectric actuator of the minute vibration removing mechanism. Sample stage device. A charged particle beam optical system, a lens barrel that houses the charged particle beam optical system, a vacuum chamber connected to the lens barrel, a sample stage device provided on a base in the vacuum chamber, and the base A charged particle beam apparatus having an X axis and a Y axis provided along
The sample stage device includes a top table for holding a sample to be observed, an intermediate table disposed below the top table, and moving the intermediate table along the X-axis direction and the Y-axis direction. A stage mechanism for positioning the sample, and a minute vibration removal mechanism for removing minute vibrations of the top table provided between the top table and the intermediate table,
The minute vibration removing mechanism includes a movable part attached to the top table, a fixed part attached to the intermediate table, an elastic support part for elastically supporting the movable part with respect to the fixed part, A piezoelectric actuator that drives the movable part with respect to the fixed part; and a control part that drives the piezoelectric actuator;
The elastic support portion is arranged to connect the four corners of the fixed portion and the four corners of the movable portion,
The piezoelectric actuators are arranged along the same straight line on both sides in the X-axis direction of the fixed part, and are identical on both sides in the Y-axis direction of the fixed part and a pair of X-axis piezoelectric actuators that expand and contract in opposite directions. A charged particle beam apparatus comprising a pair of Y-axis piezoelectric actuators arranged along a straight line and extending and contracting in opposite directions. The charged particle beam apparatus according to claim 6.
The sample stage device includes a position detection device that detects the position of the top table, and the control unit applies an applied voltage to the piezoelectric actuator based on the position of the top table detected by the position detection device. A charged particle beam device characterized by controlling. The charged particle beam apparatus according to claim 6.
The charged particle beam apparatus according to claim 1, wherein the elastic support portion is disposed along a diagonal line of the fixed portion so as to connect the four corners of the fixed portion and the four corners of the movable portion. The charged particle beam apparatus according to claim 6.
The charged particle beam apparatus, wherein the fixed part is formed in a rectangular shape, and the movable part is formed as a frame member surrounding the fixed part. The charged particle beam apparatus according to claim 6.
A charged particle beam apparatus, wherein a positive bias voltage is applied in advance to the piezoelectric actuator so that a negative voltage is not applied. The charged particle beam apparatus according to claim 6.
The charged particle beam apparatus, wherein the top table and the fixed part are formed in a square shape, and the movable part is formed as a square frame member surrounding the fixed part. The charged particle beam apparatus according to claim 6.
The control unit drives the intermediate table of the sample stage device to first align a measurement point on the sample to be observed with the optical axis, and a second step performs addressing to the measurement point. And a third step of performing autofocus to a high magnification and a fourth step of acquiring an image at a high magnification. In the fourth step, the minute vibration removing mechanism performs a nanometer order A charged particle beam apparatus characterized by removing minute residual vibrations. The charged particle beam apparatus according to claim 6.
In the first step, the intermediate table is driven by the stage mechanism with a stroke of several hundred millimeters. In the fourth step, the top table is driven by the piezoelectric actuator of the minute vibration removing mechanism. A charged particle beam device driven by a stroke of 10 nanometers. In the minute vibration removing mechanism configured to be provided between the top table and the intermediate table of the sample stage device and removing the minute vibration of the top table,
A movable part attached to the top table, a fixed part attached to the intermediate table, an elastic support part for elastically supporting the movable part relative to the fixed part, and the movable part relative to the fixed part A piezoelectric actuator for driving the unit,
The elastic support portion is arranged to connect the four corners of the fixed portion and the four corners of the movable portion,
The piezoelectric actuators are arranged along the same straight line on both sides in the X-axis direction of the fixed part, and are identical on both sides in the Y-axis direction of the fixed part and a pair of X-axis piezoelectric actuators that expand and contract in opposite directions. A micro-vibration eliminating mechanism having a pair of Y-axis piezoelectric actuators arranged along a straight line and extending and contracting in opposite directions. The minute vibration removing mechanism according to claim 14,
The micro-vibration removing mechanism, wherein the elastic support part is disposed along a diagonal line of the fixed part so as to connect the four corners of the fixed part and the four corners of the movable part. In the micro oscillating removal mechanism according to claim 14 Symbol mounting,
The fixed portion is formed in a rectangular shape, and the movable portion is formed as a frame member surrounding the fixed portion. Oite the minute vibration removing Organization of claim 14,
A micro-vibration removing mechanism, wherein a positive bias voltage is applied to the piezoelectric actuator in advance so that a negative voltage is not applied. The minute vibration removing mechanism according to claim 14,
The top table, and the fixing portion is formed in a square, the movable portion, the minute vibration rejection Organization, characterized in that it is formed as a frame member of a square surrounding the fixed portion. The minute vibration removing mechanism according to claim 14,
The intermediate table is driven with a stroke of several hundred millimeters by the stage mechanism, and the top table is driven with a stroke of several tens of nanometers by a piezoelectric actuator of the minute vibration removing mechanism. Micro vibration removal mechanism. In sample stage apparatus according to claim 1, between the front Symbol movable part and the piezoelectric actuator, a sample stage, characterized in that a least four rods. The sample stage according to claim 20,
The sample stage, wherein the movable part is formed in a rectangular shape, and the fixed part is formed as a frame member surrounding the movable part. In sample stage according to claim 20 and claim 21, wherein the movable part and the piezoelectric actuator, characterized in that they are connected by the beam-like rod is a member located in all directions of the movable portion Sample stage.   A stage equipped with a minute vibration removing mechanism using the sample stage using the rod according to claim 20 as a fine movement mechanism.   A charged particle apparatus using a stage equipped with a minute vibration removing mechanism using the rod according to claim 23 as a positioning mechanism.   24. A controller mounted with a minute vibration removing mechanism using a rod according to claim 23, wherein the controller performs positioning only with the minute vibration removing mechanism by blocking the thrust of the coarse actuator after positioning.