Stage equipment, charged particle beam equipment, and optical inspection equipment

Abstract

To provide a stage device capable of reducing a residual vibration of a floating stage (an upper table) in accordance with a rotational vibration of a lower table and improving a through-put.SOLUTION: A stage device comprises: a first table 104 that can be moved on a base 106; a second table 102 that can be moved on the first table 104 while floating, and includes a first part and a second part lower than the first part; a first position measurement device 600 that measures a position of the first part of the second table 102; a second position measurement device 300 that measures a position of the second part of the second table 102; and a computer 601 that controls a motor 200 driving the second table 102. The computer 601 drives the second table 102 on the basis of information on the position of the first part measured by the first position measurement device 600 and information on the position of the second part measured by the second position measurement device 300.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] The present invention relates to a stage device, a charged particle beam device including the stage device, and an optical inspection device.

Background Art

[0002] In processes such as semiconductor manufacturing, measurement, and inspection, an XY stage is used in a stage device to accurately determine the position of a semiconductor device such as a wafer. As the stage device, a stacked stage device in which two-stage tables (an X table and a Y table) are stacked in the vertical direction may be used.

[0003] As a drive mechanism for the XY stage, for example, there are a mechanism driven by a rotary motor and a ball screw using a linear guide, and a mechanism driven using a linear motor. In addition, a stage that performs not only movement in the XY plane but also movement parallel to the Z axis and rotational movement around the Z axis may be used for positioning a semiconductor device. In particular, in recent years, in order to achieve ultra-precise positioning, a non-contact type floating stage using a hydrostatic bearing or electromagnetic force is often used.

[0004] In a stacked stage device, a configuration in which only the upper table is constituted by a floating stage and the lower table is guided by a linear guide, or a configuration in which both the upper and lower tables are floating stages may be used. In this case, in order to achieve high-precision positioning, the upper table (floating stage) is driven by a drive mechanism in six-axis directions (the translational directions of X, Y, Z and the rotational directions of θx, θy, θz) with excellent controllability, and a configuration for controlling the center of gravity of the upper table in six-axis directions is adopted.

[0005] There are two methods for detecting the position of the levitation stage: one using an optical sensor and the other using a laser interferometer. In the method using an optical sensor (e.g., a linear scale), for example, the scale part of the linear scale is placed on the lower table and the light-receiving part is placed on the upper table, and the position of the levitation stage is detected by detecting the relative position of these two tables. In the method using a laser interferometer, the position of the levitation stage is detected by the interference of laser light and reflected waves using a laser interferometer and a reflective mirror. By using the position detected by these methods for feedback control, the position of the levitation stage can be controlled with high precision.

[0006] An example of a stack-type stage device equipped with a levitation stage is described in Patent Document 1. The stage device described in Patent Document 1 is equipped with a linear motor that generates thrust in the driving direction (Y direction) of the stage and a yoke that covers the linear motor, and the levitation part has a permanent magnet and an electromagnet, and is configured to obtain levitation force in the Z direction using the linear motor for the driving direction. [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2019-179879 [Overview of the Initiative] [Problems that the invention aims to solve]

[0008] In a stack-type stage system equipped with a levitation stage, the height positions of the centers of gravity are inherently different between the upper table (levitation stage) and the lower table. Generally, the drive mechanism of the levitation stage controls the height position of the center of gravity of the levitation stage to improve positional accuracy. As a result, the drive reaction force when the levitation stage (upper table) is driven is applied at a height different from the height position of the center of gravity of the lower table, generating a rotational moment in the lower table.

[0009] Here, let's consider the effect of rotational vibration of the lower table, using the example of measuring the position of the levitation stage using a linear scale. The signal measured by the linear scale (the signal indicating the position of the levitation stage) is superimposed with a component (a minute component on the order of nanometers) caused by the rotational vibration of the lower table. If the levitation stage is controlled to follow the position signal superimposed with this minute component (rotational vibration of the lower table), the levitation stage will be controlled to follow the rotational vibration of the lower table, increasing the rotational vibration of the levitation stage. In addition, the driving reaction force when controlling the levitation stage to follow the position acts on the lower table, leading to a further increase in the rotational vibration of the lower table.

[0010] Thus, while conventional technologies such as the one disclosed in Patent Document 1 can control the levitation stage with a simple configuration, they have the problem that residual vibration of the levitation stage (vibration remaining in the levitation stage after it has moved) increases due to rotational vibration of the table below. When the residual vibration of the levitation stage increases, the time required to wait for this residual vibration to dampen becomes longer, making it difficult to improve the throughput of the stage device.

[0011] The object of the present invention is to provide a stage device that can reduce residual vibration of the levitation stage (upper table) due to rotational vibration of the lower table, thereby improving throughput, and a charged particle beam device and an optical inspection device equipped with this stage device. [Means for solving the problem]

[0012] The stage apparatus according to the present invention comprises a base, a first table movable on the base, a second table that is movable above the first table and has a first portion and a second portion lower than the first portion, a first position measuring device for measuring the position of the first portion of the second table, a second position measuring device for measuring the position of the second portion of the second table, a motor for driving the second table, and a computer for controlling the motor. The computer drives the second table based on information about the position of the first portion measured by the first position measuring device and information about the position of the second portion measured by the second position measuring device.

[0013] The stage apparatus according to the present invention may include a base, a first table movable on the base, a second table that floats and moves on the first table, a position measuring device for measuring the relative position of the second table with respect to the first table, a motor for driving the second table, and a computer for controlling the motor. The frequency of rotational vibration of the first table is known in advance, the computer stores information about the frequency, the computer performs a filtering process to remove the frequency component from the measured value of the position measuring device, and drives the second table using the filtered measured value of the position measuring device.

[0014] The charged particle beam apparatus according to the present invention comprises a stage device, a chamber housing the stage device, and a microscope tube installed in the chamber and equipped with a charged particle source. The stage device is the stage device described above.

[0015] The optical inspection apparatus according to the present invention comprises a stage device, a chamber housing the stage device, and a microscope tube installed in the chamber and equipped with a light source. The stage device is the stage device described above. [Effects of the Invention]

[0016] According to the present invention, it is possible to provide a stage device capable of reducing residual vibration of a floating stage (upper table) associated with rotational vibration of a lower table and improving throughput, a charged particle beam device including this stage device, and an optical inspection device. BRIEF DESCRIPTION OF THE DRAWINGS

[0017] [Figure 1] It is a figure which shows the example of a structure of the conventional stack type stage apparatus. [Figure 2] It is a figure which shows the example of a structure of the conventional stack type stage apparatus provided with a floating stage. [Figure 3] It is a figure which shows the example of the method of measuring the relative position of the X table which is a floating stage. [Figure 4A] It is a figure which shows the example of the influence which rotational vibration of a Y table gives to an X table in the conventional stack type stage apparatus provided with a floating stage. [Figure 4B] It is a figure which shows the example of the attitude | position of the X table when rotational vibration arises in the Y table in the stage apparatus by an Example of this invention. [Figure 5A] It is a figure which shows the example of the waveform of the vibration of the X table when only the X table is driven. [Figure 5B] It is a figure which shows the example of the waveform of the vibration of the X table when the X table and the Y table are driven simultaneously. [Figure 6] It is a figure which shows the structure of the stage apparatus by Example 1 of this invention. [Figure 7] It is a figure which shows the difference in frequency characteristics between the measured value of the linear scale and the measured value of laser interference with respect to the rotational vibration of the Y table. [Figure 8] It is a figure which shows the flowchart of the process which moves the X table which is a floating stage in the stage apparatus by Example 1. [Figure 9A] It is a figure which shows the example of the measured value of the linear scale before a computer system performs a filtering process. [Figure 9B]This is a diagram showing an example of the filter frequency characteristics of the filter processing performed by a computer system. [Figure 9C] This is a diagram showing an example of the measured values on a linear scale after the computer system performs filter processing. [Figure 10] This is a diagram showing the configuration of the stage device according to Example 2 of the present invention. [Figure 11] This is a diagram showing an example of a vibration frequency map that records information about the frequency of the rotational vibration of the Y table. [Figure 12] This is a diagram showing a flowchart of the process of moving the X table, which is a floating stage, by the stage device according to Example 2. [Figure 13] This is a diagram showing the configuration of the stage device according to Example 3 of the present invention. [Figure 14] This is a diagram showing the configuration of the stage device according to Example 4 of the present invention. [Figure 15] This is a diagram showing a configuration example of a charged particle beam device or an optical inspection device according to Example 5 of the present invention.

Mode for Carrying Out the Invention

[0018] The stage device according to the present invention is a stack-type stage device in which two tables are arranged in the vertical direction, at least the upper table is constituted by a floating stage, and it is possible to reduce the vibration (for example, residual vibration) of the upper table (floating stage) accompanying the rotational vibration of the lower table, and it is possible to improve the throughput.

[0019] First, the stack-type stage device will be described with reference to the drawings. Hereinafter, the directions orthogonal to each other in the horizontal plane are defined as the X direction and the Y direction, and the direction perpendicular to the horizontal plane is defined as the Z direction or the height direction. The X direction, the Y direction, and the Z direction may also be referred to as the direction of the X axis, the direction of the Y axis, and the direction of the Z axis, respectively. In the drawings used in this specification, the same or corresponding components are denoted by the same reference numerals, and repeated descriptions of these components may be omitted.

[0020] Figure 1 shows an example of the configuration of a conventional stack-type stage device. The stage device shown in Figure 1 is also called an XY stage and comprises a base 106, a lower table Y table 104, and an upper table X table 102. The X table 102 has a top table 101 on top.

[0021] The base 106 is a component that supports the Y table 104 and the X table 102.

[0022] The Y-table 104 is located on top of the base 106 via a linear guide 105y and a guide carriage 103y. The Y-table 104 is driven by a Y-linear motor (not shown) and is movable on the base 106 in the Y direction (parallel to the plane of the paper). The Y-linear motor is positioned between the base 106 and the Y-table 104 and generates thrust to move the Y-table 104 in the Y direction.

[0023] A linear scale (not shown) is placed on the base 106 and the Y-table 104 for measuring the relative position between the base 106 and the Y-table 104. This linear scale measures the relative displacement of the Y-table 104 in the Y-direction relative to the base 106.

[0024] The X-table 102 is located above the Y-table 104 via linear guides 105x and guide carriages 103x. The X-table 102 is driven by an X-linear motor (not shown) and is movable on the Y-table 104 in the X direction (perpendicular to the plane of the paper). The X-linear motor is positioned between the Y-table 104 and the X-table 102 and generates thrust to move the X-table 102 in the X direction.

[0025] Linear scales (not shown) are placed on the Y-table 104 and the X-table 102 to measure the relative position between the Y-table 104 and the X-table 102. These linear scales measure the relative displacement of the X-table 102 in the X-direction relative to the Y-table 104.

[0026] An object such as a semiconductor wafer is placed on the top surface of the top table 101. The position of the object, such as a semiconductor wafer, can be determined by moving the X table 102 and the Y table 104 along the XY plane.

[0027] Next, we will describe the rotational vibration of the stack-type stage device equipped with a levitation stage and the Y-table 104, which is the table below it.

[0028] Figure 2 shows an example of the configuration of a conventional stack-type stage device equipped with a levitation stage. In the stage device shown in Figure 2, the Y-table 104 is movable in the Y direction via a linear guide 105y and a guide carriage 103y, similar to the conventional stage device (XY stage) shown in Figure 1. Below, we will mainly describe the differences in configuration between the stage device shown in Figure 2 and the stage device shown in Figure 1.

[0029] The X-table 102 is a levitation stage that obtains lift and thrust through electromagnetic thrust. The X-table 102 is driven by a motor 200 that provides thrust in the Y direction. The motor 200 consists of a Y-motor yoke 201 located on the Y-table 104 and a Y-motor coil 202 located on the X-table 102, and moves the X-table 102. The X-table 102 is driven not only by the motor 200 but also by multiple motors (not shown) that generate thrust in six axial directions, and its attitude is controlled with six degrees of freedom. The six axial directions are the X-axis, Y-axis, Z-axis, θx-axis, θy-axis, and θz-axis. The θx-axis, θy-axis, and θz-axis are directions around the X-axis, Y-axis, and Z-axis, respectively.

[0030] The multiple motors that drive the X-table 102, which is the levitation stage, are generally arranged to provide thrust to the drive center of gravity of the levitation stage so that the position of the top table 101 can be determined with high precision.

[0031] In the stage apparatus shown in Figure 2, rotational vibration occurs in the Y-table 104 when the X-table 102 is driven and when the Y-table 104 is driven, as described below.

[0032] In the stage device shown in Figure 2, unlike the conventional XY stage (Figure 1), the X table 102 is driven by thrust generated in the Y direction. When the X table 102 is driven, the driving reaction force 203 of this thrust acts on the Y table 104 via the Y motor yoke 201. Since the driving reaction force 203 acts at a height position different from the height position (height direction position) of the center of gravity of the Y table 104, rotational vibration (particularly rotational vibration around the X axis) occurs in the Y table 104.

[0033] Furthermore, when the Y-table 104 is driven to position it, the driving force 204 of the Y-table 104 acts in opposite directions to the driving reaction force 203, so the Y-table 104 experiences rotational vibration around the X-axis due to the rotational moment 205 around the X-axis.

[0034] Figure 2 shows an example in which the Y-table 104 moves via the linear guide 105y and the guide carriage 103y. Even when the Y-table 104 is a levitation stage, in a stacked stage device, the height positions of the centers of gravity are essentially different between the upper table (X-table 102) and the lower table (Y-table 104), so the Y-table 104 experiences rotational vibrations similar to those shown in Figure 2.

[0035] Furthermore, the Y-table 104 may experience rotational vibrations around the Y-axis due to rotational moments around the Y-axis, or rotational vibrations around the Z-axis due to rotational moments around the Z-axis. In the following explanation, as a representative example, we will describe the case in which the Y-table 104 experiences rotational vibrations around the X-axis due to rotational moments 205 around the X-axis.

[0036] Figure 3 shows an example of a method for measuring the relative position of the X-table 102, which is a levitation stage. As an example, Figure 3 shows a method for measuring the position of the X-table 102 using a linear scale 300, which is an optical sensor. Note that other optical sensors or position sensors using capacitance may be used to measure the position of the X-table 102 besides the linear scale 300.

[0037] The linear scale 300 comprises a light source that emits light, a scale section 302 that reflects light from the light source, and a light receiving section 301 that reads the light reflected by the scale section 302. In the linear scale 300 shown in Figure 3, as an example, the light receiving section 301 is equipped with a light source.

[0038] The scale unit 302 is installed on the upper (top surface) of the Y table 104. The light receiving unit 301 is installed on the lower (bottom surface) of the X table 102. With this arrangement, the linear scale 300 can measure the relative position of the X table 102 with respect to the Y table 104. The X table 102 may also be equipped with six or more linear scales (not shown) to detect the orientation of the X table 102 in the six axes. The measured values ​​of the linear scale 300 are used for feedback control calculations to drive the X table 102.

[0039] Figure 4A shows an example of the effect of rotational vibration of the Y-table 104 on the X-table 102 in a conventional stack-type stage device equipped with a levitation stage.

[0040] When rotational vibration occurs in the Y-table 104, the component of the rotational vibration of the Y-table 104 is superimposed on the measurement value of the linear scale 300. When the X-table 102, which is a levitation stage, is controlled to follow this measurement value, the X-table 102 is feedback-controlled so that the relative displacement amount with respect to the Y-table 104 becomes zero. As a result, rotational vibration occurs in the X-table 102 in accordance with the rotational vibration of the Y-table 104. As shown in Figure 4A, this rotational vibration tilts the X-table 102 with respect to the horizontal plane 400, reducing the positioning accuracy of the X-table 102. Therefore, the time it takes for the vibration (residual vibration) to decay becomes a waiting time, which reduces the throughput of the stage device.

[0041] Figure 4B shows an example of the posture of the X-table 102 when rotational vibration occurs in the Y-table 104 in a stage apparatus according to an embodiment of the present invention. In the stage apparatus according to an embodiment of the present invention, as described below, even when rotational vibration occurs in the Y-table 104, the effect of this rotational vibration can be reduced, so that the X-table 102 can maintain an ideal posture (for example, a posture in which the X-table 102 is parallel to the horizontal plane 400 as shown in Figure 4B), and the throughput of the stage apparatus can be improved.

[0042] Figures 5A and 5B show examples of vibration waveforms of the X-table 102, which is a levitation stage.

[0043] Figure 5A shows an example of the vibration waveform of the X-table 102 when only the X-table 102 is driven. Since only the X-table 102 is driven, only the drive reaction force 203 (Figure 2) acts on the Y-table 104. The X-table 102 experiences vibrations as shown in Figure 5A due to the rotational vibration of the Y-table 104 caused only by the drive reaction force 203.

[0044] Figure 5B shows an example of the vibration waveform of the X-table 102 when the X-table 102 and Y-table 104 are driven simultaneously. In this case, a driving force 204 (Figure 2) acts on the Y-table 104, generating a rotational moment 205 around the X-axis, so the rotational vibration of the Y-table 104 increases compared to when only the X-table 102 is driven. Therefore, as shown in Figure 5B, the X-table 102 experiences larger vibrations than those shown in Figure 5A.

[0045] In other words, when the X table 102 and Y table 104 are driven simultaneously, the vibration of the X table 102 due to the rotational vibration of the Y table 104 increases compared to when only the X table 102 is driven.

[0046] In the following, a stage apparatus, a charged particle beam apparatus, and an optical inspection apparatus according to embodiments of the present invention will be described with reference to the drawings. [Examples]

[0047] Figure 6 shows the configuration of a stage device according to Embodiment 1 of the present invention. The stage device according to this embodiment is a stack-type stage device equipped with a levitation stage. In the following, the configuration of the stage device according to this embodiment will be mainly described in terms of how it differs from the conventional stage device shown in Figure 2.

[0048] The stage apparatus according to this embodiment includes a first position measuring device for measuring the position of a first part of the X table 102, a second position measuring device for measuring the position of a second part of the X table 102, and a computer system 601. The first part of the X table 102 is the upper surface of the top table 101. That is, the position of the first part of the X table 102 is close to the position of the object placed on the top table 101 (for example, a semiconductor wafer), and is above the rotation center 604 of the X table 102. The second part of the X table 102 is the part of the X table 102 that is below the first part and below the rotation center 604 of the X table 102. The rotation center 604 of the X table 102 is the rotation center when the X table 102 is floating.

[0049] The first position measuring device is, for example, a laser interferometer 600. The laser interferometer 600 comprises a light source 605 that emits laser light 603 and a reflective mirror 602 installed on the upper surface of the top table 101. The laser interferometer 600 measures the position of the X table 102 in the Y and Z directions based on the interference between the laser light 603 emitted from the light source 605 and the reflected light of the laser light 603 by the reflective mirror 602. Although Figure 6 shows the configuration of the laser interferometer 600 for measuring the position of the X table 102 in the Y direction, the laser interferometer 600 can measure the position of the X table 102 in the X and Z directions by providing a configuration for measuring the position of the X table 102 in the X direction (for example, a reflective mirror not shown).

[0050] By using the laser interferometer 600, measurements can be taken at a position close to the location of the object (e.g., a semiconductor wafer) placed on the top table 101, and the position of the X table 102 on which the object is placed can be measured with high accuracy and with little Abbe error. Alternatively, a planar scale placed on the top table 101 can be used as the first position measurement device instead of the laser interferometer 600.

[0051] A second position measuring device is, for example, a linear scale 300. The linear scale 300 measures the relative position of the X table 102 with respect to the Y table 104.

[0052] The computer system 601 is a computer-based device that performs calculations and control related to the stage equipment. For example, the computer system 601 moves the X-table 102 by controlling the motor 200. The computer system 601 performs feedback control calculations using information about the position of the X-table 102 measured by the laser interferometer 600 and information about the position of the X-table 102 measured by the linear scale 300, and drives the motor 200 to generate levitation and thrust forces for the X-table 102, thereby controlling the X-table 102.

[0053] The X-table 102 is a levitation stage that is controlled by the computer system 601 to move and change its attitude. When levitating, the X-table 102 is controlled to follow the rotational vibration of the Y-table 104, and may cause rotational vibrations. The center of this rotational vibration is the rotation center 604 of the X-table 102.

[0054] The first position measuring device, the laser interferometer 600, measures the position of the first part of the X-table 102. The second position measuring device, the linear scale 300, measures the position of the second part of the X-table 102. That is, the laser interferometer 600 is positioned to measure the position of the part of the X-table 102 above the rotation center 604, and the linear scale 300 is positioned to measure the position of the part of the X-table 102 below the rotation center 604.

[0055] In this embodiment, the stage apparatus is configured such that the laser interferometer 600 and the linear scale 300 are positioned opposite to each other in the height direction with respect to the rotation center 604 of the X-table 102. This configuration allows the vibration of the X-table 102 to be measured in opposite phases by the laser interferometer 600 and the linear scale 300 when rotational vibration occurs in the Y-table 104. In other words, in this embodiment, the sign of the measurement value from the laser interferometer 600 and the sign of the measurement value from the linear scale 300 change in opposite directions.

[0056] The computer system 601 calculates the rotational vibration frequency of the Y-table 104 using the method described later with reference to Figure 7. In this embodiment, the stage apparatus may calculate the rotational vibration frequency of the Y-table 104 in real time at high speed using an FPGA (field-programmable gate array), or it may be calculated offline using a computer system other than the computer system 601.

[0057] One method to prevent vibration of the X-table 102 due to rotational vibration of the Y-table 104 is to perform a filtering process to remove the frequency component of the rotational vibration of the Y-table 104 from the measured value of the linear scale 300 (the signal of the relative position of the X-table 102 with respect to the Y-table 104). This filtering calculation may be performed by the computer system 601 using digital processing, or it may be performed using an FPGA.

[0058] The computer system 601 can reduce the influence of rotational vibration of the Y-table 104 on the X-table 102 by controlling the X-table 102 using a position signal (measured value on the linear scale 300) from which the frequency components of rotational vibration of the Y-table 104 have been removed. In other words, the computer system 601 can reduce the residual vibration of the X-table 102 (levitation stage) caused by the rotational vibration of the Y-table 104.

[0059] Another method to reduce the impact of rotational vibration of the Y-table 104 on the X-table 102 is as follows: The computer system 601 may calculate a drive signal for the motor 200 of the X-table 102 that cancels out the frequency components of the rotational vibration of the Y-table 104, and then drive the X-table 102 by providing this drive signal to the motor 200. By providing this drive signal to the motor 200, the computer system 601 can control the X-table 102 with a signal from which the frequency components of the rotational vibration of the Y-table 104 have been removed.

[0060] Figure 7 shows the difference in frequency characteristics between the measurements of the linear scale 300 and the laser interferometer 600 for the rotational vibration of the Y-table 104. Using Figure 7, the method by which the computer system 601 calculates the frequency of the rotational vibration of the Y-table 104 will be explained.

[0061] The scale vibration characteristic 701 is the frequency characteristic of the vibration of the X-table 102 measured using the linear scale 300. The scale vibration characteristic 701 can be obtained by converting the measurement signal of the linear scale 300, that is, the time change (amplitude) of the position of the X-table 102 measured by the linear scale 300, into the frequency domain.

[0062] The laser vibration characteristic 702 is the frequency characteristic of the vibration of the X-table 102 measured using the laser interferometer 600. The laser vibration characteristic 702 can be obtained by converting the measurement signal from the laser interferometer 600, that is, the time change (amplitude) of the position of the X-table 102 measured by the laser interferometer 600, into the frequency domain.

[0063] The linear scale 300 measures the position of the X table 102 using the Y table 104 as a reference. Therefore, the measured value of the linear scale 300, i.e., the scale vibration characteristics 701, contains a wealth of information about the rotational vibration of the Y table 104. On the other hand, the laser interferometer 600 directly measures the position of the X table 102 without using the Y table 104 as a reference. Therefore, the measured value of the laser interferometer 600, i.e., the laser vibration characteristics 702, does not contain much information about the rotational vibration of the Y table 104.

[0064] Therefore, the amplitude of the vibration in the scale vibration characteristic 701 is larger than that of the laser vibration characteristic 702. The amplitude of the scale vibration characteristic 701 is thought to be largest at the frequency of rotational vibration of the Y-table 104.

[0065] Furthermore, as described above, in the stage apparatus according to this embodiment, when rotational vibration occurs in the Y table 104, the laser interferometer 600 and the linear scale 300 detect vibrations of the X table 102 in opposite phases to each other. That is, the sign of the measured value of the laser interferometer 600 and the sign of the measured value of the linear scale 300 change in opposite directions to each other, and the scale vibration characteristic 701 and the laser vibration characteristic 702 are in an opposite phase relationship to each other, as shown in Figure 7.

[0066] From the above, the computer system 601 can determine that the scale vibration characteristic 701 and the laser vibration characteristic 702 are in opposite phase to each other (the measurement signal of the laser interferometer 600 and the measurement signal of the linear scale 300 are in opposite phase to each other), and that the frequency at which the amplitude of the scale vibration characteristic 701 is largest is the rotational vibration frequency 703 of the Y table 104.

[0067] The computer system 601 can determine the phase of the vibration of the X table 102 and the frequency 703 of the rotational vibration of the Y table 104 when rotational vibration occurs in the Y table 104, for example, by using Fourier transform. Specifically, the computer system 601 performs a Fourier transform on the signal of the measurement value of the linear scale 300 and the signal of the measurement value of the laser interferometer 600 to obtain the frequency characteristics of the vibration of the X table 102 (scale vibration characteristics 701 and laser vibration characteristics 702) as shown in Figure 7, and by calculating the phase and amplitude of the scale vibration characteristics 701 and laser vibration characteristics 702, it can calculate the frequency 703 of the rotational vibration of the Y table 104.

[0068] In the above explanation, we described the case where rotational vibration occurs around the X-axis of the Y-table 104 (Figure 2). However, the rotational vibration frequency 703 of the Y-table 104 can be calculated in the same way when rotational vibration occurs around the Y-axis or the Z-axis of the Y-table 104.

[0069] To calculate the rotational vibration frequency 703 of the Y-table 104, methods other than using the Fourier transform may be used, such as measuring the frequency characteristics of the X-table 102 which is the object of control, identifying the frequency by matching the model output with the position detection signal using a vibration transfer function model, or calculating it mechanically using artificial intelligence (AI).

[0070] Figure 8 is a flowchart showing the process by which the stage device according to this embodiment moves the X-table 102, which is a floating stage.

[0071] In process S801, the computer system 601 determines the coordinates (target coordinates) of the position where the X table 102 will be moved, based on the specified coordinates on the object (e.g., a semiconductor wafer) placed on the top table 101. The specified coordinates on the object are, for example, coordinates specified by the user of the stage device or a device connected to the stage device, and can be one of the coordinates of a position on the object that the user wants to observe.

[0072] In process S802, the computer system 601 creates a drive command for the motor 200 based on the current coordinates and target coordinates of the X table 102, and drives the motor 200 to start moving the X table 102.

[0073] In process S803, the computer system 601 measures the position of the moving X-table 102 using the linear scale 300. Once the linear scale 300 measures the position of the X-table 102 in six axes (translational directions of the X, Y, and Z axes, and rotational directions of the θx, θy, and θz axes), the computer system 601 can calculate the position and orientation of the X-table 102 in these six axes.

[0074] In process S804, the computer system 601 derives the rotational vibration frequency 703 of the Y-table 104 using the measured values ​​of the laser interferometer 600 and the linear scale 300, in accordance with the method described with reference to Figure 7.

[0075] In process S805, the computer system 601 performs filtering on the measured values ​​of the linear scale 300 to remove the component of rotational vibration of the Y table 104 with a frequency of 703 from the measured values ​​of the linear scale 300 (signals indicating the position of the X table 102). This filtering process will be described later with reference to Figure 9. Note that the computer system 601 may perform filtering on the measured values ​​of the linear scale 300 in only one of the six axis directions (for example, the Y axis), or on the measured values ​​of the linear scale 300 in all six axis directions.

[0076] In process S806, the computer system 601 generates a drive command for the motor 200 that drives the X-table 102. Using a feedback control method, the computer system 601 calculates a drive command for the motor 200 that drives the X-table 102 in at least one of the six axes (translational directions of the X, Y, and Z axes, and rotational directions of the θx, θy, and θz axes) from the measured values ​​of the filtered linear scale 300. Existing control laws, such as PID control, can be used for the feedback control calculation. In this way, the computer system 601 can determine at least one of the translational distance and rotation angle of the X-table 102 when it is moved.

[0077] In process S807, the computer system 601 drives the motor 200 based on the generated drive command to control the position and orientation of the X table 102 and move the X table 102.

[0078] Processes S803 through S807 are performed periodically while X table 102 is being moved.

[0079] In process S808, the computer system 601 completes the movement of the X-table 102 when the X-table 102 has reached the target coordinates. Once the movement of the X-table 102 is complete, processing on the object (e.g., observation of the object, such as a semiconductor wafer) is performed.

[0080] In process S809, the computer system 601 determines whether processing for the object has been completed. The computer system 601 can determine whether processing for the object has been completed based on information provided, for example, through the user of the stage device or a device connected to the stage device. If processing for the object has not been completed, the process returns to S801.

[0081] The following describes the filtering process performed in step S805 of the flowchart shown in Figure 8, with reference to Figures 9A to 9C. As mentioned above, the computer system 601 performs filtering to remove the component with a frequency of 703 of rotational vibration of the Y table 104 from the measured value of the linear scale 300 (the signal indicating the position of the X table 102).

[0082] Figure 9A shows an example of the measurement values ​​of the linear scale 300 before the computer system 601 performs filtering. The position of the X table 102 measured by the linear scale 300 is represented by a waveform in which minute vibration components caused by the rotational vibration of the Y table 104 are superimposed on the rotational vibration of the X table 102.

[0083] Figure 9B shows an example of the filter frequency characteristics 902 of the filtering process performed by the computer system 601. The filter frequency characteristics 902 can be determined using the rotational vibration frequency 703 of the Y-table 104 and the width 901 of the rotational vibration frequency 703. The width 901 of the rotational vibration frequency 703 can be determined arbitrarily. The filter frequency characteristics 902 have the characteristic of reducing frequency components (frequency components determined by the width 901) in the vicinity of the rotational vibration frequency 703 of the Y-table 104. Any existing filter, such as a notch filter, can be used as a digital filter having such filter frequency characteristics 902.

[0084] Figure 9C shows an example of the measured values ​​of the linear scale 300 after filtering by the computer system 601. The computer system 601 removes the component with frequency 703 of the rotational vibration of the Y table 104 from the measured values ​​of the linear scale 300 by applying a filter with the filter frequency characteristics 902 shown in Figure 9B to the measured values ​​of the linear scale 300 shown in Figure 9A. In the measured values ​​of the linear scale 300 shown in Figure 9C, the minute vibration components caused by the rotational vibration of the Y table 104, as seen in Figure 9A, have been removed, and only the vibration components caused by the rotational vibration of the X table 102 remain.

[0085] The computer system 601 moves the X-table 102 based on the measured values ​​of the linear scale 300, which have been filtered as shown in Figure 9C (processes S806 and S807 in Figure 8). As a result, the stage device according to this embodiment can reduce the effects of rotational vibration of the Y-table 104, enable precise control of the position and orientation of the X-table 102, reduce residual vibration of the X-table 102, and improve throughput. [Examples]

[0086] The stage apparatus according to Embodiment 2 of the present invention will be described below. In the following, the differences between the stage apparatus according to Embodiment 1 and the stage apparatus according to Embodiment 2 will be mainly described.

[0087] In this embodiment, the rotational vibration frequency 703 of the Y-table 104 is known from prior measurements and structural analysis. The rotational vibration frequency 703 of the Y-table 104 can be determined in advance by methods such as actual measurement through impact tests and vibration mode measurements, or by calculation using a 3D analysis tool.

[0088] In this embodiment, since the rotational vibration frequency 703 of the Y-table 104 is known in advance, the measurement of the position of the first part of the X-table 102 using the laser interferometer 600 can be omitted. Information about the rotational vibration frequency 703 of the Y-table 104 is stored in the computer system 601. The computer system 601 can also store a vibration frequency map in which the rotational vibration frequency 703 of the Y-table 104 is recorded.

[0089] Figure 10 shows the configuration of the stage apparatus according to this embodiment. The stage apparatus according to this embodiment has the same configuration as the stage apparatus according to Embodiment 1 (Figure 6), but differs from the stage apparatus according to Embodiment 1 in that it does not have a laser interferometer 600 (reflection mirror 602, light source 605).

[0090] Figure 11 shows an example of a vibration frequency map 1101 that records information about the rotational vibration frequency 703 of the Y-table 104. In a stage device, the load and orientation of the stage (Y-table 104) change according to the stage coordinates (coordinates on the Y-table 104), and it is conceivable that the rotational vibration frequency 703 will change as a result. Therefore, the rotational vibration frequency 703 may be recorded in the vibration frequency map 1101 for each stage coordinate, and the component of rotational vibration frequency 703 that is removed by filtering may be changed according to the stage coordinate.

[0091] Figure 11 shows an example of a vibration frequency map 1101 in which the rotational vibration frequency 703 of the Y-table 104 is recorded for each stage coordinate. In the example shown in Figure 11, the vibration frequency map 1101 is circular, reflecting the shape of the semiconductor wafer, which is the object being studied. Although Figure 11 shows the vibration frequency map 1101 in two dimensions using the X and Y axes, the vibration frequency map 1101 can also be represented multidimensionally using directions such as the Z axis, θx axis, θy axis, and θz axis.

[0092] Figure 12 is a flowchart showing the process by which the stage device according to this embodiment moves the X-table 102, which is a floating stage.

[0093] Processes S1201 to S1203 are the same as processes S801 to S803 shown in Figure 8.

[0094] In process S1204, the computer system 601 performs filtering on the measured value of the linear scale 300, similar to process S805 shown in Figure 8 in Example 1, to remove the component of rotational vibration frequency 703 of the Y table 104 from the measured value of the linear scale 300 (signal indicating the position of the X table 102). However, since the computer system 601 has previously stored the rotational vibration frequency 703 of the Y table 104, it uses the stored rotational vibration frequency 703 of the Y table 104 to perform filtering in the same way as in Example 1. If the component of rotational vibration frequency 703 to be removed by filtering is to be changed according to the stage coordinates, the computer system 601 uses the information recorded in the vibration frequency map 1101.

[0095] Processes S1205 through S1208 are the same as processes S806 through S809 shown in Figure 8.

[0096] Similar to the stage apparatus of Embodiment 1, the stage apparatus according to this embodiment can reduce the effects of rotational vibration of the Y table 104, enable precise control of the position and orientation of the X table 102, reduce residual vibration of the X table 102, and improve throughput. [Examples]

[0097] The stage apparatus according to Examples 1 and 2 reduces the effect of vibration of the Y table 104 on the X table 102 through passive control. The stage apparatus according to Example 3 of the present invention reduces the effect of vibration of the Y table 104 on the X table 102 through active control.

[0098] Figure 13 shows the configuration of the stage device according to this embodiment. The stage device according to this embodiment is further equipped with a vibration sensor 1301 and an actuator 1302 for damping minute vibrations of the Y table 104, in addition to the stage device according to Embodiment 1 (Figure 6).

[0099] The vibration sensor 1301 detects vibrations of the Y-table 104. Any vibration detection device can be used for the vibration sensor 1301, such as an acceleration sensor, strain sensor, laser displacement sensor, and capacitance sensor. The vibration of the Y-table 104 can be detected by detecting at least one of the position, velocity, and acceleration of the Y-table 104.

[0100] The actuator 1302 can drive the Y-table 104. Any actuator can be used for the actuator 1302, such as an actuator using a piezoelectric element. Alternatively, the actuator 1302 can be configured as a planar motor consisting of a permanent magnet and a coil.

[0101] The computer system 601 actively controls the vibration of the Y-table 104 by performing feedback control. Specifically, the computer system 601 uses the information about the vibration of the Y-table 104 detected by the vibration sensor 1301 to generate a drive signal to drive the actuator 1302 to dampen the vibration of the Y-table 104, and drives the actuator 1302 with this drive signal to control the vibration of the Y-table 104.

[0102] The number of vibration sensors 1301 and actuators 1302 can be arbitrarily determined, and there may be one or more so that at least one axis direction can be controlled from the six axes (X axis, Y axis, Z axis, θx axis, θy axis, and θz axis).

[0103] The stage apparatus according to this embodiment can reduce the effects of rotational vibration of the Y-table 104 through feedback control using a vibration sensor 1301 and an actuator 1302, enabling precise control of the position and orientation of the X-table 102, reducing residual vibration of the X-table 102, and improving throughput. [Examples]

[0104] The stage apparatus according to Embodiment 4 of the present invention reduces the effect of vibration of the Y table 104 on the X table 102 by active control, similar to the stage apparatus according to Embodiment 3.

[0105] Figure 14 shows the configuration of the stage device according to this embodiment. In this embodiment, the stage device is a floating stage, with the Y-table 104 being the same as in the stage device according to Embodiment 1 (Figure 6). That is, in this embodiment, the stage device does not have the guide carriage 103y and linear guide 105y as in the stage device according to Embodiment 1, but it does have a motor movable element 1401, a motor stator 1402, and a position detection sensor 1403.

[0106] The motor movable element 1401 and the motor stator 1402 impart levitation and thrust forces to the Y-table 104 in six axes (X-axis, Y-axis, Z-axis, θx-axis, θy-axis, and θz-axis) by electromagnetic force, making the Y-table 104 a levitation stage. Alternatively, the motor movable element 1401 and the motor stator 1402 may be configured as a planar levitation type, with one equipped with a permanent magnet and the other with a coil.

[0107] The position detection sensor 1403 measures the position of the Y-table 104. Any device can be used for the position detection sensor 1403; for example, a position measurement sensor such as a linear scale or a laser interferometer, or a current sensor such as a Hall element may be used.

[0108] In the stage device according to this embodiment shown in Figure 14, a drive mechanism (motor movable element 1401 and motor stator 1402) is provided that allows the Y-table 104 to be controlled in six axial directions. Therefore, rotational vibration of the Y-table 104 can be actively reduced without using vibration sensors or actuators (Embodiment 3). As a result, the stage device according to this embodiment can more effectively reduce the influence of vibration of the Y-table 104 on the X-table 102 through active control.

[0109] Furthermore, by combining the active vibration damping configurations described in Examples 3 and 4 with the passive vibration damping configurations described in Examples 1 and 2, it is possible to realize a stage device that further effectively reduces the vibration of the X-table 102. [Examples]

[0110] Example 5 describes a charged particle beam apparatus and an optical inspection apparatus according to an embodiment of the present invention. The charged particle beam apparatus and optical inspection apparatus according to this embodiment include a stage apparatus described in any one of Examples 1 to 4.

[0111] First, we will describe the charged particle beam apparatus according to this embodiment.

[0112] Figure 15 shows an example of the configuration of a charged particle beam apparatus according to this embodiment. Below, as an example, a semiconductor measuring device 1504 will be described as a charged particle beam apparatus. Figure 15 is a schematic cross-sectional view of the semiconductor measuring device 1504.

[0113] The semiconductor measuring device 1504, which is a charged particle beam apparatus according to this embodiment, is, for example, a scanning electron microscope such as a length measuring SEM, and can inspect an object 1503 such as a semiconductor wafer using a charged particle beam (electron beam). The semiconductor measuring device 1504 includes a stage device 1505 for positioning the object 1503, a vacuum chamber 1501 housing the stage device 1505, and a microscope tube 1502.

[0114] The stage device 1505 is a stack-type stage device equipped with a levitation stage, as described in Examples 1 to 4.

[0115] The vacuum chamber 1501 is depressurized by a vacuum pump (not shown) to create a vacuum inside at a pressure lower than atmospheric pressure. The vacuum chamber 1501 is supported by vibration damping mounts 1506 to prevent vibrations from being transmitted from the floor.

[0116] The microscope tube 1502 is installed in the vacuum chamber 1501 and is equipped with a charged particle beam source 1510 as the beam source, and is a charged particle beam microscope tube that irradiates the object 1503 with a charged particle beam. In this embodiment, the beam source 1510 is an electron source, and the microscope tube 1502 is an electron optical system microscope tube that irradiates the object 1503 with an electron beam.

[0117] The semiconductor measuring device 1504 positions the object 1503 using the stage device 1505, irradiates the object 1503 with an electron beam from the microscope tube 1502, and images the pattern formed on the object 1503 to measure the line width of a minute pattern on the order of nanometers and evaluate its shape accuracy. The stage device 1505 measures the position of the stage using at least one of the laser interferometer 600 and the linear scale 300, and performs feedback control calculations using the computer system 601.

[0118] Next, an optical inspection apparatus according to this embodiment will be described. The optical inspection apparatus according to this embodiment can inspect an object 1503 using light. The optical inspection apparatus according to this embodiment has a configuration similar to the charged particle beam apparatus shown in Figure 15, but the lens barrel 1502 differs from that of the charged particle beam apparatus. The lens barrel 1502 of the optical inspection apparatus according to this embodiment is an optical lens barrel equipped with a light source as a beam source 1510, which irradiates the object 1503 with a beam.

[0119] In this embodiment, the stage apparatus, charged particle beam apparatus, and optical inspection apparatus can reduce the residual vibration of the X table 102 (levitation stage) caused by minute rotational vibrations of the Y table 104, thereby improving the accuracy of measurements on the nanometer order, such as semiconductor measurement. Furthermore, since the time required to wait for the damping of residual vibrations after movement of the levitation stage can be shortened, it also contributes to improved throughput.

[0120] It should be noted that the present invention is not limited to the embodiments described above, and various modifications are possible. For example, the embodiments described above are explained in detail to make the present invention easier to understand, and the present invention is not necessarily limited to embodiments having all the configurations described. Furthermore, it is possible to replace parts of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add configurations from other embodiments to the configuration of one embodiment. Furthermore, it is possible to delete parts of the configuration of each embodiment, or to add or replace other configurations. [Explanation of symbols]

[0121] 101…Top table, 102…X table, 103x…Guide carriage, 103y…Guide carriage, 104…Y table, 105x…Linear guide, 105y…Linear guide, 106…Base, 200…Motor, 201…Y motor yoke, 202…Y motor coil, 203…Drive reaction force, 204…Drive force of Y table, 205…Rotational moment, 300…Linear scale, 301…Light receiving unit, 302…Scale unit, 400…Horizontal plane, 600…Laser interferometer, 601…Computer system, 602…Reflective mirror, 603…Laser light, 60 4... Rotation center of the X table, 605... Light source, 701... Scale vibration characteristics, 702... Laser vibration characteristics, 703... Rotational vibration frequency of the Y table, 901... Frequency range of rotational vibration, 902... Filter frequency characteristics, 1101... Vibration frequency map, 1301... Vibration sensor, 1302... Actuator, 1401... Motor movable element, 1402... Motor stator, 1403... Position detection sensor, 1501... Vacuum chamber, 1502... Lens tube, 1503... Object, 1504... Semiconductor measuring device, 1505... Stage device, 1506... Vibration damping mount, 1510... Beam source.

Claims

1. A base and, A first table that is movable on the base, A second table is capable of floating and moving above the first table, and has a first portion and a second portion that is lower than the first portion. A first position measuring device for measuring the position of the first portion of the second table, A second position measuring device for measuring the position of the second portion of the second table, A motor that drives the second table, A computer that controls the motor, Equipped with, The computer derives the frequency of rotational vibration of the first table based on the measurement values ​​of the first position measuring device and the measurement values ​​of the second position measuring device, and drives the second table using the frequency. A stage apparatus characterized by the following features.

2. A base and, A first table that is movable on the base, A second table is capable of floating and moving above the first table, and has a first portion and a second portion that is lower than the first portion. A first position measuring device for measuring the position of the first portion of the second table, A second position measuring device for measuring the position of the second portion of the second table, A motor that drives the second table, A computer that controls the motor, Equipped with, The first portion of the second table is the part above the center of rotation when the second table is floating. The second portion of the second table is the portion below the center of rotation, The computer derives the frequency of rotational vibration of the first table based on the frequency characteristics of the measured values ​​of the first position measuring device and the frequency characteristics of the measured values ​​of the second position measuring device, and drives the second table using the said frequency. A stage apparatus characterized by the following features.

3. A base and, A first table that is movable on the base, A second table is capable of floating and moving above the first table, and has a first portion and a second portion that is lower than the first portion. A first position measuring device for measuring the position of the first portion of the second table, A second position measuring device for measuring the position of the second portion of the second table, A motor that drives the second table, A computer that controls the motor, Equipped with, The computer drives the second table based on the information about the position of the first part measured by the first position measuring device and the information about the position of the second part measured by the second position measuring device. The frequency of the rotational vibration of the first table is known in advance. The computer stores a map in which the frequency is recorded for each coordinate on the first table. A stage apparatus characterized by the following features.

4. The computer performs a filtering process to remove the frequency component from the measured value of the second position measuring device, and drives the second table using the filtered measured value of the second position measuring device. The stage apparatus according to claim 1.

5. The computer calculates a drive signal for the motor that cancels out the frequency component, and provides the drive signal to the motor to drive the second table. The stage apparatus according to claim 1.

6. The computer determines at least one of the translational distance and rotation angle of the second table based on the measurement value of the first position measuring device and the measurement value of the second position measuring device. The stage apparatus according to any one of claims 1 to 3.

7. The first portion of the second table is the part above the center of rotation when the second table is floating. The second portion of the second table is the portion below the center of rotation. The stage apparatus according to claim 1 or 3.

8. The first position measuring device is a laser interferometer equipped with a mirror installed on the top of the second table, The second position measuring device is an optical sensor that measures the relative position of the second table with respect to the first table. The stage apparatus according to any one of claims 1 to 3.

9. A sensor for detecting vibrations of the first table, The actuator that drives the first table, Equipped with, The computer uses the information detected by the sensor to drive the actuator to dampen the vibration of the first table. The stage apparatus according to any one of claims 1 to 3.

10. Stage equipment and, A chamber housing the aforementioned stage device, A microscope tube, installed in the aforementioned chamber and equipped with a charged particle source, Equipped with, The stage device is the stage device described in any one of claims 1 to 3. A charged particle beam apparatus characterized by the following features.

11. Stage equipment and, A chamber housing the aforementioned stage device, A microscope tube, which is installed in the chamber and has a light source, Equipped with, The stage device is the stage device described in any one of claims 1 to 3. An optical inspection device characterized by the following features.

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