Stage device and charged particle beam device provided with the stage device

Abstract

The present application provides a kind of stage device and the charged particle beam device with the stage device, sufficient position accuracy of sample can be ensured in suspended type stage.The stage device (100) includes: lower stage (20) moving in Y axis direction;Upper stage (10) is floated from lower stage (20), at least in X axis direction orthogonal to Y axis direction moves;Heat exchanger for cooling Y workbench (2) of lower stage (20) using cooling medium;And control device for controlling the inclination of lower stage (20) with Y workbench (2) cooled by heat exchanger as reference.

Description

TECHNICAL FIELD

[0001] The present application relates to a stage device and a charged particle beam device provided with the stage device. BACKGROUND

[0002] In the field of semiconductors, a stage device for moving and positioning a sample such as a semiconductor wafer is known. In addition, in a device using a charged particle beam such as an electron beam, it is necessary to handle a sample such as a semiconductor wafer in a high vacuum environment, and the stage device also operates in a high vacuum environment.

[0003] The structure of the stage device is classified into a guide rail type stage in which movement is limited to the direction of the guide rail, and a levitation type stage in which the stage is floated from a base portion and moves in a non-contact state with the base portion according to control. In the guide rail type stage, in order to achieve planar movement, a two-layer stage structure can be adopted in which the upper stage moves in a direction orthogonal to the moving direction of the lower stage. On the other hand, in the levitation type stage, there is a single-axis type stage in which the movable range is large in one direction and narrow in the other direction, and a planar type stage in which planar movement over a large range is possible. In addition, a stage that moves in a plane can also be configured by combining a single-axis type levitation type stage with a guide rail type stage. Furthermore, as a levitation mechanism of the levitation type stage, there are a magnetic levitation type in which the levitation amount is controlled using electromagnetic force, and an air bearing type in which the levitation amount is controlled using the pressure of gas.

[0004] In addition, the magnetic levitation type stage is classified into a type having an electromagnet that applies levitation force to the stage and a linear motor that applies thrust force in the single-axis direction, and a type having a shaft motor that can have both functions of levitation and propulsion. In both types, the stage can move while maintaining a non-contact state. Although a stabilization mechanism is not obtained in the non-contact state, high position accuracy of the stage can be achieved by advanced control of the levitation type stage.

[0005] When the levitation type stage is placed in a vacuum environment, heat generated by a motor that drives the stage cannot be dissipated by solid heat conduction, so a heat dissipation unit using a cooling medium needs to be provided. For example, Patent Literature 1 discloses a technology in which a driving portion inside a fine movement stage that moves a wafer is cooled with a cooling medium. In addition, Patent Literature 2 discloses a technology in which a coil of a motor is cooled with a cooling medium in a stage device in which a substrate stage that holds a wafer is moved using a shaft motor. Furthermore, Patent Literature 3 discloses a technology regarding a cooling device that cools a linear motor that moves a wafer stage that holds a wafer.

[0006] Prior Art Documents

[0007] Patent Documents

[0008] Patent Document 1: Japanese Patent Application Laid-Open (JP-A) No. 2005-32817

[0009] Patent Document 2: Japanese Patent Application Laid-Open (JP-A) No. 2001-61269

[0010] Patent Document 3: Japanese Patent Application Laid-Open (JP-A) No. 2005-64229 SUMMARY

[0011] PROBLEMS TO BE SOLVED BY THE INVENTION

[0012] In processes of manufacturing, measuring, inspecting, and the like of a semiconductor wafer, it is necessary to position the wafer correctly. In order to position the semiconductor wafer correctly, it is necessary to know the position of a stage that moves the wafer correctly. As a technique of measuring the position of the stage correctly, there is a technique of using a distance measuring device of a laser interferometer type in which a strip-shaped mirror is provided on the stage and laser light is irradiated to the reflecting surface thereof, and distance measurement is performed using interference of incident light and reflected light. The distance measuring device of the laser interferometer type in recent years is capable of distance measurement with an accuracy of the order of picometer. If distance measurement can be performed with an accuracy of the order, it is considered that wafer position accuracy sufficient for practical use can be obtained. However, in reality, since various error factors that can cause deterioration of wafer position accuracy in a levitation type stage are combined, it is difficult to secure sufficient wafer position accuracy.

[0013] Therefore, the present application provides a technique of securing sufficient position accuracy of a sample in a levitation type stage.

[0014] MEANS OF SOLVING THE PROBLEM

[0015] The stage device of the present application includes: a first stage capable of moving in a first direction; a second stage levitated from the first stage and capable of moving at least in a second direction orthogonal to the first direction; a first cooling portion that cools a table of the first stage with a cooling medium; and a control device that controls inclination of the second stage with the table of the first stage cooled by the first cooling portion as a reference.

[0016] EFFECT OF THE INVENTION

[0017] According to the present application, it is possible to secure sufficient position accuracy of a sample in a levitation type stage. BRIEF DESCRIPTION OF DRAWINGS

[0018] Figure 1 is a view showing the overall structure of the stage device of Example 1.

[0019] Figure 2 is a sectional view of the stage device of Example 1.

[0020] Figure 3 is a diagram showing a control device of the stage device of Example 1.

[0021] Figure 4 is a diagram showing the overall structure of the stage device of Example 2.

[0022] Figure 5 is a diagram showing the overall structure of the charged particle beam device of Example 3. DETAILED DESCRIPTION

[0023] Embodiments of the present application are described in detail based on the drawings. In the following embodiments, constituent elements (including element steps, etc.) are not essential unless otherwise specified, and are not necessarily essential in principle, etc.

[0024] <Example 1>

[0025] Figure 1 is a diagram showing the overall structure of the stage device of Example 1. Figure 2 is a sectional view of the stage device of Example 1. The stage device 100 of Example 1 is a device that moves a placed sample (for example, a semiconductor wafer) in the X-axis direction and the Y-axis direction. The stage device 100 is provided with an upper stage 10 that moves in the X-axis direction, a lower stage 20 that moves in the Y-axis direction, a cooling water pipe 30 that supplies cooling water for cooling the upper stage 10 and the lower stage 20, and a control device 50 (refer to Figure 3 ) that controls the upper stage 10 and the lower stage 20. The upper stage 10 is floated from the lower stage 20 by the action of a magnetic force between the upper stage 10 and the lower stage 20, and moves at least in the X-axis direction orthogonal to the Y-axis direction.

[0026] (Upper stage 10)

[0027] The upper stage 10 is constituted with an X table 1 as a center. The upper stage 10 is floated from a Y table 2 of the lower stage 20, and moves in the X-axis direction with respect to the lower stage 20. The upper stage 10 mainly moves in the X-axis direction, but the moving direction thereof includes a deviation of an error degree with respect to the X-axis direction. In addition, the upper stage 10 can not move only in the X-axis direction but move in a plane. On the upper stage 10, various mechanisms are installed, such as a mechanism that floats the upper stage 10 from the Y table 2, a mechanism that moves the upper stage 10 in the X-axis direction, and a mechanism that moves the upper stage 10 in the Y-axis direction. The various mechanisms are provided inside the X table 1. The various mechanisms become heat sources, and heat is conducted to the X table 1.

[0028] On the X stage 1, a strip-shaped mirror for measuring the X coordinate, i.e., an X mirror 3, and a strip-shaped mirror for measuring the Y coordinate, i.e., a Y mirror 4, are fixed. The X mirror 3 has a reflecting surface perpendicular to the X axis, and reflects laser light irradiated from a distance measuring device of a laser interferometer type not shown. In addition, the Y mirror 4 has a reflecting surface perpendicular to the Y axis, and reflects laser light irradiated from a distance measuring device of a laser interferometer type not shown. Thereby, the X coordinate of the reflecting surface of the X mirror 3 and the Y coordinate of the reflecting surface of the Y mirror 4 can be measured. By measuring the X coordinate and the Y coordinate of the reflecting surfaces, the XY coordinates of the X stage 1 on which the X mirror 3 and the Y mirror 4 are fixed and the XY coordinates of a sample placed on the X stage 1 can be calculated.

[0029] (lower stage 20)

[0030] The lower stage 20 is configured with the Y stage 2 as a center. The lower stage 20 moves in the Y axis direction. The lower stage 20 mainly moves in the Y axis direction, but the moving direction thereof includes a deviation of an error degree with respect to the Y axis direction. In addition, the lower stage 20 can not move only in the Y axis direction but move in a plane. The lower stage 20 moves in the Y axis direction on two guide rails 5 arranged in the Y axis direction. The lower stage 20 is restricted by the two guide rails 5 so as not to move in a direction other than the Y axis direction. The lower stage 20 of Embodiment 1 is of a guide rail type, but can be a levitation type stage. The lower stage 20 has various mechanisms such as a mechanism for levitating the upper stage 10 from the Y stage 2, a mechanism for moving the lower stage 20 in the Y axis direction, and the like. The various mechanisms are provided inside the Y stage 2. The various mechanisms become heat sources, and heat is conducted to the Y stage 2.

[0031] (cooling water piping 30)

[0032] The stage device 100 is sometimes used in a sample chamber in which manufacturing, measurement, or inspection of a sample such as a semiconductor wafer is performed. In addition, in a device using a charged particle beam such as an electron beam, it is necessary to process a sample such as a semiconductor wafer in a high vacuum environment, and the stage device 100 also operates in a high vacuum environment. In order to suppress malfunction and thermal expansion and the like due to heat generated by mechanisms for moving the upper stage 10 and the lower stage 20, it is necessary to cool the upper stage 10 and the lower stage 20. In Embodiment 1, the stage device 100 has the cooling water piping 30 for supplying a cooling medium to the upper stage 10 and the lower stage 20 in order to cool the upper stage 10 and the lower stage 20. In Embodiment 1, cooling water is used as the cooling medium. As a cooling method of the stage device 100, water cooling, air cooling, and gas cooling and the like can be adopted.

[0033] Cooling water, supplied from a constant-temperature water tank (not shown), is supplied to both the upper platform 10 and the lower platform 20 via cooling water piping 30. Cooling water piping 30 includes a connector 31, a destination pipe 32, a connecting pipe 33, a return pipe 34, and a connector 35. The constant-temperature water tank supplies cooling water to the destination pipe 32, which is connected to connector 31. The destination pipe 32 connects to a heat exchanger 17 (see reference 17) located inside the X-stage workbench 1 of the upper platform 10. Figure 2 Connection. The outgoing piping 32 is arranged along the Y-axis direction from the connector 31, and is arranged along the Y-axis direction again after a U-turn. The outgoing piping 32 arranged along the Y-axis direction is supported by the support member 21 provided on the lower mounting platform 20. By making a U-turn on the outgoing piping 32 in this way, the part of the U-turn will be displaced as the lower mounting platform 20 moves in the Y-axis direction. For this purpose, a flexible material such as resin pipe is used as the cooling water piping 30.

[0034] The outgoing piping 32, after passing through support member 21, is arranged along the X-axis direction and then continues along the X-axis direction after a U-turn. The outgoing piping 32, arranged along the X-axis direction, is supported by support member 11 provided on the upper platform 10. By making a U-turn in this manner, the U-shaped bend is displaced as the upper platform 10 moves along the X-axis. The outgoing piping 32, after passing through support member 11, connects to connector 12 fixed to the X-stage 1. Thus, cooling water supplied from the constant temperature water tank is supplied to the heat exchanger 17 of the X-stage 1 via connector 31, outgoing piping 32, and connector 12. As a result, the X-stage 1, which is in contact with the surface of the heat exchanger 17 through which the cooling water flows, is cooled.

[0035] Cooling water, after cooling the X worktable 1, is supplied from connector 13 fixed to the X worktable 1 to the heat exchanger 27 of the Y worktable 2 via connecting pipe 33. Connecting pipe 33 is supported by support member 11. The connecting pipe 33, supported by support member 11, is arranged along the X-axis direction and then along the X-axis direction after a U-turn. Then, connecting pipe 33 connects to connector 22 fixed to the Y worktable 2. Thus, cooling water, after cooling the X worktable 1, is supplied to the heat exchanger 27 of the Y worktable 2 via connector 13, connecting pipe 33, and connector 22. As a result, the Y worktable 2, which is in contact with the surface of the heat exchanger 27 through which the cooling water flows, is cooled.

[0036] Cooling water, after cooling the Y-stage 2, returns to the constant-temperature water tank via a return pipe 34 from the connector 23 fixed to the Y-stage 2. The return pipe 34 is supported by a support member 21. Supported by the support member 21, the return pipe 34 is arranged along the Y-axis direction, and after a U-turn, it continues along the Y-axis direction. Then, the return pipe 34 connects to the connector 35 of the constant-temperature water tank. The cooling water, after being cooled by the constant-temperature water tank, is then supplied back to the connector 31.

[0037] The outgoing conduit 32 and the connecting conduit 33 are connected to the surface 16 of the upper platform 10, which is perpendicular to the Y-axis. Additionally, the connecting conduit 33 and the returning conduit 34 are connected to the surface 28 of the lower platform 20, which is perpendicular to the Y-axis. The perpendicular surface 16 of the upper platform 10, connected to the outgoing conduit 32 and the connecting conduit 33, and the perpendicular surface 28 of the lower platform 20, connected to the connecting conduit 33 and the returning conduit 34, are on the same side. Alternatively, the perpendicular surface 16 of the upper platform 10, connected to the outgoing conduit 32 and the connecting conduit 33, and the perpendicular surface 28 of the lower platform 20, connected to the connecting conduit 33 and the returning conduit 34, may be on different sides. For example, the outgoing piping 32 and the connecting piping 33 may be configured such that the surface 18 of the upper platform 10 is perpendicular to the X-axis direction, and the connecting piping 33 and the returning piping 34 are connected to the surface 28 of the lower platform 20 is perpendicular to the Y-axis direction.

[0038] (Inclination angle of the upper platform 10)

[0039] The control device 50 measures the tilt angle of the upper platform 10 and controls it to make the upper platform 10 horizontal. The Y-stage 2 has a vertical surface 24 perpendicular to the Y-axis direction, on which a linear scale 25 (see reference) is mounted. Figure 3 Additionally, the X-stage 1 has a vertical surface 14 perpendicular to the Y-axis direction, on which a sensor 15 for reading a linear scale 25 is mounted (see reference). Figure 3Vertical plane 24 is opposite vertical plane 14. By reading the linear scale 25 with sensor 15, the height of the X-stage 1 relative to the Y-stage 2 (Z displacement measurement) can be measured. The linear scale 25 is, for example, a plate-shaped scale with a pattern formed by a fine grating that reflects laser light, used in conjunction with sensor 15 that emits laser light and reads the reflected light. If the reflection pattern formed on the linear scale 25 is two-dimensional, it is possible to measure not only the displacement of the relative position of the linear scale 25 and sensor 15 in the Z-axis direction, but also the displacement in the X-axis direction. Furthermore, by measuring the height of one linear scale with two sensors, the tilt angle of the X-stage 1 can be determined from the difference between the two heights. That is, the pitch angle of the X-stage 1 moving in the X-axis direction can be measured. Using this principle, by adding two more sets of linear scales 25 and sensors 15, the yaw angle and roll angle can be measured. Thus, high-precision tilt angle measurement can be performed with a simple structure.

[0040] (Heat exchanger)

[0041] Figure 2 It is along Figure 1 The cross-sectional view of line S1-S2. (Refer to...) Figure 2 The structure for cooling the X worktable 1 and Y worktable 2 is described in detail. The X worktable 1 is made of aluminum alloy. Inside the X worktable 1 is a heat exchanger 17 formed of stainless steel piping. This heat exchanger 17 is a cooling unit that uses a cooling medium to cool the X worktable 1. In the heat exchanger 17 built into the X worktable 1, the surface of the piping through which the cooling medium (e.g., cooling water) passes contacts the X worktable 1, thereby cooling the X worktable 1. Furthermore, the piping constituting the heat exchanger 17 is formed by bending a single pipe, and this single pipe has an inlet and outlet for cooling water. Mechanisms are installed on the X worktable 1 such as those for levying the upper platform 10 from the Y worktable 2, for moving the upper platform 10 in the X-axis direction, and for moving the upper platform 10 in the Y-axis direction. These mechanisms act as heat sources, and heat is conducted to the X worktable 1. Because the X worktable 1 is made of aluminum alloy, the temperature gradient caused by heat conduction is small, which reduces temperature rise and temperature unevenness.

[0042] Similarly, the Y-stage 2 is also made of aluminum alloy. The Y-stage 2 also has a heat exchanger 27 made of stainless steel piping inside. This heat exchanger 27 is a cooling unit that uses a cooling medium to cool the Y-stage 2. In the heat exchanger 27 built into the Y-stage 2, the surface of the piping through which the cooling medium passes contacts the Y-stage 2, thereby cooling the Y-stage 2. The piping constituting the heat exchanger 27 is also formed by bending a single pipe, and each single pipe has an inlet and outlet for cooling water. Mechanisms are installed on the Y-stage 2 to levitate the upper platform 10 from the Y-stage 2 and to move the lower platform 20 in the Y-axis direction. These mechanisms act as a heat source, and heat is conducted to the Y-stage 2. Because the Y-stage 2 is also made of aluminum alloy, the temperature gradient caused by heat conduction is small, which reduces temperature rise and temperature unevenness.

[0043] (Guide rail 5 and sliding unit 26)

[0044] The lower stage 20, centered on the Y-stage 2, is restricted by two guide rails 5 and cannot move in directions other than the Y-axis. Furthermore, the guide rails 5 are fixed within the sample chamber 40. The lower stage 20 has sliding units 26 disposed at its four corners, which contact the guide rails 5. A rotating body is disposed inside the sliding unit 26, causing the contact with the guide rails 5 to become a rolling contact. As a result, the sliding unit 26 and the guide rails 5 form a low-friction, backlash-free contact structure.

[0045] When the temperature of the Y-stage 2 rises, because the movement of the Y-stage 2 along the Y-axis is unrestricted, the Y-stage 2 expands freely in the Y-axis direction. On the other hand, because the guide rail 5 restricts movement in directions other than the Y-axis, the Y-stage 2 cannot expand in directions other than the Y-axis. Therefore, the expansion caused by the temperature rise is absorbed by the bend of the Y-stage 2 in a wedge shape. That is, when the Y-stage 2 bends in a wedge shape, in Figure 2 On the right side, the Y-stage 2 becomes higher on the left and lower on the right. Figure 2 On the left side, the Y-stage 2 becomes lower on the left and higher on the right. On the other hand, the X-stage 1 moves towards the positive or negative side of the X coordinate. Then, as the X-stage 1 moves, the tilt angle of the X-stage 1 is measured with the Y-stage 2 as a reference at the location of the moving target.

[0046] (Control device 50)

[0047] The control device 50 controls the stage drive mechanism 60 to move the lower stage 20 in the Y-axis direction, or to move the upper stage 10 in both the Y-axis and X-axis directions, or to change the tilt of the upper stage 10. The stage drive mechanism 60 includes a mechanism for leviting the upper stage 10 from the Y-stage 2, a mechanism for moving the upper stage 10 in the X-axis direction, a mechanism for moving the upper stage 10 in the Y-axis direction, and a mechanism for moving the lower stage 20 in the Y-axis direction. In Embodiment 1, the control device 50 measures the tilt angle of the X-stage 1 and controls the tilt of the X-stage 1 based on the measured tilt angle to make the X-stage 1 horizontal.

[0048] The control device 50 uses the Y-stage 2 of the lower platform 20, which is cooled by the heat exchanger 27, as a reference to control the tilt of the upper platform 10. Specifically, the control device 50 uses the vertical plane 24 provided on the Y-stage 2 as a reference, measures the position of the upper platform 10 at multiple locations, and controls the tilt of the upper platform 10 based on the measurement results.

[0049] Furthermore, the control device 50 measures the XY coordinates of the X stage 1 of the upper stage 10 based on the laser light reflected from the X mirror 3 and Y mirror 4. And, based on the XY coordinates of the X stage 1, the control device 50 controls the movement of the upper stage 10 and the lower stage 20, so that the sample placed on the upper stage 10 is moved to the required position.

[0050] Next, refer to Figure 3 The hardware structure of the control device 50 is described below. The control device 50 includes a processor 51, a communication interface 52 (hereinafter referred to as I / F), a main storage device 53, an auxiliary storage device 54, an input / output I / F 55, and a bus 56 that communicatively connects the above modules.

[0051] The processor 51 is a central processing unit that controls the operation of various parts of the stage device 100. The processor 51 may be, for example, a CPU (Central Processing Unit), a DSP (Digital Signal Processor), or an ASIC (Application Specific Integrated Circuit). The processor 51 executablely loads programs stored in the auxiliary storage device 54 into the working area of ​​the main storage device 53. The main storage device 53 stores programs to be executed by the processor 51, data processed by the processor, etc. The main storage device 53 may be flash memory, RAM (Random Access Memory), ROM (Read Only Memory), etc. The auxiliary storage device 54 stores various programs and various data. The auxiliary storage device 54 may store, for example, an operating system (OS), various programs, various tables, etc. The auxiliary storage device 54 may include non-volatile semiconductor memory (flash memory, EPROM (Erasable Programmable ROM)), silicon disk drives, solid-state drives, hard disk drives (HDDs), etc.

[0052] Communication I / F 52 is an interface for enabling the stage assembly 100 to be communicatively connected to an external device via a network. Input / output I / F 55 is used to input the measurement results of the sensor 15 and the distance measuring device 70 connected to the input / output I / F 55. The distance measuring device 70 is a laser interferometer-type distance measuring device that illuminates the reflecting surfaces of the X-mirror 3 and the Y-mirror 4 with laser light. The processor 51 calculates the tilt angle of the X-stage 1 based on the measurement results of the sensor 15, and controls the stage drive mechanism 60 to level the X-stage 1 based on the calculated tilt angle of the X-stage 1. In addition, the processor 51 measures the XY coordinates of the X-stage 1 and the XY coordinates of the sample placed on the X-stage 1 based on the measurement results of the distance measuring device 70. Furthermore, the input / output I / F 55 outputs a drive instruction to the stage drive mechanism 60 connected to the input / output I / F 55. The stage drive mechanism 60 moves the lower stage 20 in the Y-axis direction, or moves the upper stage 10 in the Y-axis and X-axis directions, or changes the tilt angle of the upper stage 10 according to the drive instruction from the control device 50.

[0053] (Effect of Example 1)

[0054] The control device 50 uses the Y-stage 2, cooled by the heat exchanger 27, as a reference to control the tilt of the upper stage 10, thereby ensuring the upper stage 10 is level with good precision. In Embodiment 1, because the movement of the Y-stage 2 in directions other than the Y-axis is restricted by the guide rail 5, the Y-stage 2 would thermally expand and bend into a V-shape if it were not cooled. Since the Y-stage 2, which serves as the calculation reference for the tilt angle of the X-stage 1, is bending, even if the X-stage 1 is controlled to be level with the Y-stage 2 as a reference, the X-stage 1 will actually be level. Therefore, in Embodiment 1, by cooling the Y-stage 2, the bending of the Y-stage 2, which serves as the reference, can be suppressed, and the X-stage 1 can be leveled with good precision. As a result, the XY plane of the XY coordinates of the sample can be kept parallel to the plane of the upper stage 10 with good precision. When the plane measuring the position coordinates of the upper stage 10 is at the same height as the plane measuring the position coordinates of the sample, even if there is some angular deviation between them, the coordinate error is small. However, if there is a deviation in height between the two, a coordinate error proportional to the product of the height deviation and the angular deviation will occur. In Example 1, by ensuring that the upper stage 10 is accurately level, the angular deviation is reduced, the aforementioned coordinate error is reduced, and the positioning accuracy of the sample is improved.

[0055] In addition, in Embodiment 1, by using the cooling water from cooling the X worktable 1 of the upper platform 10 to cool the Y worktable 2 of the lower platform 20, the two worktables can be cooled with common cooling water.

[0056] In addition, in Embodiment 1, by using magnetic force to make the upper platform 10 float from the lower platform 20, it is possible to prevent the effects of thermal expansion of the lower platform 20 from being directly transmitted to the upper platform 10.

[0057] Furthermore, in Embodiment 1, by using the vertical plane 24 provided on the Y-stage 2 of the lower stage 20 as a reference, the position of the upper stage 10 can be measured at multiple points, allowing for the calculation of the tilt of the upper stage 10 using a simple structure. Additionally, in Embodiment 1, by installing a linear scale 25 on the vertical plane 24 and a sensor 15 for reading the linear scale 25 on the vertical plane 14, the tilt of the upper stage 10 can be calculated using a simple structure.

[0058] Furthermore, in Embodiment 1, the outgoing piping 32 is arranged along the Y-axis direction and then along the Y-axis direction again after a U-turn. The U-turn portion is displaced as the Y-stage 2 moves along the Y-axis direction, thus ensuring that cooling medium can be supplied to the Y-stage 2 even if the lower platform 20 moves. Similarly, the outgoing piping 32 is arranged along the X-axis direction and then along the X-axis direction again after a U-turn, with the U-turn portion displaced as the X-stage 1 moves along the X-axis direction, thus ensuring that cooling medium can be supplied to the X-stage 1 even if the upper platform 10 moves.

[0059] Furthermore, in Embodiment 1, the outgoing piping 32 and the connecting piping 33 are connected to the surface 16 of the X worktable 1, which is perpendicular to the Y-axis direction, and the connecting piping 33 and the returning piping 34 are connected to the surface 28 of the Y worktable 2, which is perpendicular to the Y-axis direction. This allows the piping to be connected to the vertical surfaces on the same side of both the X worktable 1 and the Y worktable 2, thus simplifying the piping connection. Additionally, the connection surfaces of the piping can be appropriately selected to prevent vibrations caused by the circulation of cooling water.

[0060] In addition, in Embodiment 1, by installing a heat exchanger 17, which is made by bending a single pipe, inside the X workbench 1, and a heat exchanger 27, which is made by bending a single pipe, inside the Y workbench 2, the X workbench 1 and the Y workbench 2 can be cooled efficiently.

[0061] In Embodiment 1, the lower stage 20 is a guide rail type, but it can also be a suspended stage. When the lower stage 20 is a suspended stage, since there is no restriction on movement by the guide rail 5, thermal deformation will not occur. However, from the viewpoint of the stage assembly 100, there is a possibility of thermal deformation due to the mixing of components made of various materials. When materials with different coefficients of linear expansion are connected, bending occurs where the component with greater expansion due to temperature rise is on the outside of the radius of curvature, while the component with less expansion is on the inside of the radius of curvature. Therefore, even if the lower stage 20 is a suspended stage, the X stage 1 can be leveled with good accuracy by suppressing the thermal expansion of the Y stage 2, which serves as a reference.

[0062] In Embodiment 1, a single-line (one-stroke shape) cooling water piping 30 is constructed when cooling both workbench X 1 and workbench Y 2. However, the cooling water piping 30 can also branch to cool workbench X 1 and workbench Y 2 separately. The cooling water that has branched and cooled each workbench returns to the main piping. Vibration of the water flow is prone to occur at the point where the piping converges. The one-stroke shape cooling water piping 30 structure of Embodiment 1 has the effect of preventing vibration caused by the cooling water flow. In the event of piping vibration, the vibration will be transmitted to the upper platform 10 and the lower platform 20. By eliminating the main piping to prevent vibration, it helps to prevent vibration of workbench X 1 and workbench Y 2.

[0063] Alternatively, independent cooling water pipes 30 can be installed in the upper platform 10 and the lower platform 20 respectively. However, the upper platform 10 moves in the X-axis direction and also moves with the lower platform 20 in the Y-axis direction. Therefore, the cooling water pipes 30 of the upper platform 10 need to have U-shaped bends for following the movement of the lower platform 20, and also U-shaped bends for following the movement of the upper platform 10. Furthermore, since the lower platform 20 moves in the Y-axis direction, the cooling water pipes 30 of the lower platform 20 need to have U-shaped bends for following the movement of the lower platform 20. That is, when independent cooling water pipes 30 are installed in the upper platform 10 and the lower platform 20 respectively, there is redundant cooling water pipe 30. Therefore, a single-stroke cooling water pipe 30 has the effect of reducing the amount of piping.

[0064] When the one-stroke-shaped cooling water piping 30 cools either the X worktable 1 or the Y worktable 2, the cooling water temperature rises accordingly with the heat received at that location, resulting in a decrease in the cooling effect on the other worktable. Therefore, in the one-stroke-shaped cooling water piping 30, the worktable supplied with cooling water first has a greater cooling effect. In Embodiment 1, by supplying cooling water to the upper platform 10 first, the X worktable 1 can be effectively cooled.

[0065] <Example 2>

[0066] Figure 4 This is a cross-sectional view of the mounting platform device in Embodiment 2. Figure 4This is a cross-sectional view obtained by cutting the stage device 100 of Embodiment 2 with a plane perpendicular to the X-axis. For structures the same as in Embodiment 1, the same reference numerals as in Embodiment 1 are used, and their descriptions are omitted. In Embodiment 2, as a structure for cooling the Y-stage 2, instead of embedding the heat exchanger 27 inside the Y-stage 2, an external heat sink 128 is installed on the lower stage 20. The heat sink 128 has a flow path 129 for the flow of cooling medium inside. Alternatively, the heat sink 128 of Embodiment 2 can also be a heat sink without cooling medium flow, and can have multiple fins to increase the surface area.

[0067] Stainless steel pipes can be embedded inside the radiator 128 to serve as flow path 129, or grooves can be machined into the base material of the radiator 128 and a cover can be added to form flow path 129.

[0068] exist Figure 4 The structure of the upper stage 10 is described in more detail than in Example 1. The upper stage 10 includes an X-stage 1 and an X-reflector 3 as described in Example 1 (see Figure 1). Figure 1 4) and Y-reflector, 6) top worktable, 7) chuck and 8) coil.

[0069] A coil 8 of a Z motor is mounted on the X worktable 1. A yoke 9, paired with the Z motor, is mounted on the Y worktable 2. The Z motor applies a force (i.e., levitation force) in the Z direction to the upper mounting platform 10, comprising the coil 8 through which current flows and the yoke 9, which is made of a magnetic material. Because the Z motor has a relatively small range of motion, the yoke 9 is made of a permanent magnet or a magnetic material such as iron that is not magnetic. When a permanent magnet is used, attractive and repulsive forces are generated between the coil 8 and the magnetic yoke 9. However, when a non-magnetic yoke 9 is used, only an attractive force is generated. Therefore, when a non-magnetic yoke 9 is used, it is configured such that the yoke 9 is on the upper side and the coil 8 is on the lower side. Thus, by controlling the balance between the downward force formed by gravity and the upward force formed by the attractive force of magnetism applied to the coil 8, the coil 8 is made to float to the required height.

[0070] Coils 8 are positioned at the four corners of the X-stage 1. Each of the four coils 8 is independently controlled by a control device 50. The control device 50 controls the levitation amount, pitch angle, and roll angle of the upper stage 10. Because the upper stage 10 moves significantly in the X-axis direction, it needs to generate the same electromagnetic force regardless of the position of the stationary yoke 9 relative to the moving coils 8. If the yoke 9 is composed solely of magnetic material, and it is... Figure 4The shape extends in the depth direction of the paper surface, so even if the upper stage 10 moves in the X-axis direction, the relationship between the coil 8 and the yoke 9 remains the same. Therefore, there are 4 coils 8 and 2 yokes 9. That is, 2 coils 8 correspond to 1 yoke 9. The X-stage 1 is equipped with a linear motor that applies thrust in the X-axis direction and a mechanism for following the movement of the lower stage 20 in the Y-axis direction, but... Figure 4 This structure has been omitted.

[0071] In Example 2, an X-mirror 3, a Y-mirror 4, and a chuck 7 are mounted on the top stage 6. The chuck 7 is a component used to mount a sample 80, such as a semiconductor wafer. When positioning the sample 80, directly measuring its position is difficult; therefore, the XY coordinates of the sample 80 are measured by measuring the positions of the reflecting surfaces of the X-mirror 3 and Y-mirror 4. Therefore, it is important to ensure that the positional relationship between the X-mirror 3 and Y-mirror 4 and the sample 80 remains unchanged. For this purpose, either the chuck 7 is constructed from a material that is resistant to thermal deformation, or the X-mirror 3 and Y-mirror 4 are mounted on the top stage 6. The top stage 6 and the X-stage 1 are an integral structure, but by using a structure that connects them with a column in the middle, the influence of deformation generated in the X-stage 1 on the position and angle of the X-mirror 3 and Y-mirror 4 can be reduced. Furthermore, the structure of the upper stage 10 in Example 2 can also be applied to the upper stage 10 in Example 1.

[0072] (Effect of Example 2)

[0073] Because the Y-stage 2 is equipped with various components, such as a mechanism that moves the lower stage 20 in the Y-axis direction, the lower stage 20 has a complex shape. By preparing a heat sink 128 that is separate from the lower stage 20 with its complex shape, it is possible to prevent the lower stage 20 from becoming complex. In addition, the manufacturing of the lower stage 20 becomes easier, and the manufacturing precision of the lower stage 20 is improved.

[0074] Other effects are the same as in Example 1, so their description is omitted.

[0075] <Example 3>

[0076] Figure 5 This is a structural diagram of the charged particle beam device in Embodiment 3. The charged particle beam device 200 includes a stage device 100 inside. The stage device 100 inside the charged particle beam device 200 is the stage device 100 described in Embodiments 1 and 2. The charged particle beam device 200 includes an electron microscope that irradiates a sample 80, such as a semiconductor wafer, to be observed with an electron beam and magnifies the image. The electron microscope includes an electron optics system tube 90, a stage device 100, a sample chamber 40, and a distance measuring device 70.

[0077] The electron optics system's lens barrel 90 has a charged particle source from which a particle beam irradiates the sample 80. To avoid scattering caused by gas molecules when irradiating the sample 80 with the particle beam (electron beam), the sample 80 is placed in a vacuum environment. Therefore, the sample chamber 40 functions as a vacuum cavity. Figure 5 Although the cooling water piping 30 is not shown, it is installed in the sample chamber 40. Figure 1 The cooling water piping 30 is shown. The stage device 100 moves the chuck 7 carrying the sample 80 in the X-axis and Y-axis directions. Figure 5 The diagram shows a cross-sectional view of the Y-reflector 4, obtained by cutting with a plane perpendicular to the X-axis. The vertical plane on the right side of the diagram is the reflecting surface of the Y-reflector 4. The distance measuring device 70 illuminates this reflecting surface with laser 71 to measure the Y-coordinate of the Y-reflector 4. This distance measuring device 70 is a laser interferometer-type distance measuring device. The distance measuring device 70 is fixed to the sample chamber 40. Figure 5 Although not illustrated, an X-ray reflector 3 and a distance measuring device 70 for measuring the X-coordinate of the X-ray reflector 3 by irradiating the reflective surface of the X-ray reflector 3 with a laser at a position rotated 90° are set. Based on the Y-coordinate of the Y-ray reflector 4 and the X-coordinate of the X-ray reflector 3, the XY coordinates of the sample 80 placed on the stage device 100 are calculated.

[0078] The electron optical system tube 90 is fixed to the sample chamber 40. Electron microscopy observation of the sample is at high magnification, so the distance between the electron microscope and the sample 80 cannot be too great. Therefore, the distance between the electron optical system tube 90 and the sample 80 is small. On the other hand, the X-mirror 3 and Y-mirror 4 on the upper stage 10 may move to directly below the electron optical system tube 90 as the upper stage 10 moves. To prevent the electron optical system tube 90 from contacting the X-mirror 3 and Y-mirror 4, the uppermost part of the X-mirror 3 and Y-mirror 4 needs to be lower than the lowermost part of the electron optical system tube 90. Therefore, the uppermost part of the X-mirror 3 and Y-mirror 4 cannot be significantly higher than the top surface of the sample 80. The reflecting surfaces of the X-mirror 3 and Y-mirror 4 are not used up to the very top of the vertical surface; the portion ensuring verticality extends only slightly away from the corner edge. Therefore, the laser 71 emitted by the laser interferometer-type distance measuring device 70 must be positioned lower than the top surface of the sample 80. Therefore, the height of the plane (height of laser 71) on which the position measurement of the XY coordinates of the upper stage 10 is performed is lower than the top surface of the sample 80. The stage device 100 is to locate the position of the electron beam irradiation on the top surface of the sample 80, which is the XY coordinate of the top surface of the sample 80.

[0079] One of the principles of distance measurement is Abbe's principle: distance measurement on parallel lines results in greater error compared to measuring distance along the extensions of two points on the object being measured. For the top surface of sample 80, measuring the XY coordinates of the upper stage 10 on a plane with misaligned heights follows a similar pattern to the increased error described by Abbe's principle. The increased error, as indicated by Abbe's principle, can be explained by the fact that the axes of the object being measured and the actual measured part are not perfectly parallel. Therefore, the measurement error decreases when the two are nearly perfectly parallel. Using this principle, it can be assumed that if the upper stage 10 can be made nearly perfectly horizontal, the positioning accuracy of the sample can be improved.

[0080] To keep the suspended upper stage 10 horizontal, it is necessary to determine the tilt angle of the upper stage 10, and control the upper stage 10 to be horizontal based on this tilt angle. Z-motors (coils 8) located at the four corners of the upper stage 10 can be used as actuators for control. The tilt angle of the upper stage 10 can be measured simply and with good accuracy using the method described in Example 1. Therefore, when the measurement accuracy of the tilt angle of the upper stage 10 is improved, the accuracy of the control used to keep the upper stage 10 horizontal is improved, and the positioning accuracy of the sample is improved.

[0081] (Effect of Example 3)

[0082] The charged particle beam device 200 of Example 3 has the same effect as that of Example 1, and its description is omitted.

[0083] Furthermore, the present invention is not limited to the above embodiments, and includes various modifications. The above embodiments have been described in detail for ease of understanding, but are not limited to having all the described structures. Additionally, a portion of the structure of one embodiment can be replaced with the structure of another embodiment, and structures of other embodiments can be added to the structure of one embodiment. Furthermore, for a portion of the structure of each embodiment, other structures can be added, deleted, or replaced.

[0084] In Example 1, both worktable X 1 and worktable Y 2 were cooled, but worktable Y 2 could also be cooled only. Furthermore, in Example 1, worktable X 1 and worktable Y 2 were cooled in that order, but worktable Y 2 and worktable X 1 could also be cooled in that order.

[0085] The suspended upper platform 10 in Examples 1 to 3 can be of the type having an electromagnet that applies buoyancy to the upper platform 10 and a linear motor that applies thrust in a single axis direction, or it can be of the type having an axis motor that can perform both levitation and propulsion functions.

[0086] The upper platform 10 in Examples 1 to 3 is a magnetic levitation type that uses electromagnetic force to achieve levitation, but it can also be an air bearing type that uses gas pressure to achieve levitation.

[0087] Explanation of reference numerals in the attached figures

[0088] 1: X-stage 2: Y-stage 3: X-reflector 4: Y-reflector 5: Guide rail 6: Top stage 7: Chuck 8: Coil 9: Yoke 10: Upper stage 11: Support 12: Connector 13: Connector 14: Vertical plane 15: Sensor 17: Heat exchanger 20: Lower stage 21: Support 22: Connector 23: Connector 24: Vertical plane 25: Linear scale 26: Sliding unit 27: Heat exchanger 30: Cooling water piping 31: Connector 32: Outgoing piping 33: Connecting piping 34: Return piping 35: Connector 40: Sample chamber 50: Control device 51: Processor 52: Communication I / F 53: Main storage device 54: Auxiliary storage device 55: Input / output I / F 56: Bus 60: Stage drive mechanism 70: Distance measuring device 80: Sample 90: Electro-optical system lens barrel 100: Stage device 128: Heat sink 129: Flow path 200: Charged particle beam device

Claims

1. A platform device, characterized in that, include: A first platform, which is movable in a first direction; A second platform, which floats from the first platform, is capable of moving at least in a second direction orthogonal to the first direction; The first cooling unit uses a cooling medium to cool the worktable of the first mounting platform; and A control device that controls the tilting of the second mounting platform based on the worktable of the first mounting platform cooled by the first cooling unit.

2. The platform device as described in claim 1, characterized in that: It also includes a second cooling unit, which uses a cooling medium to cool the worktable of the second mounting platform. The cooling medium used to cool one of the worktables of the first and second mounting platforms is also used to cool the other of the worktables of the first and second mounting platforms.

3. The platform device as described in claim 2, characterized in that: The cooling medium is used to cool the worktable of the second mounting stage after it has been used to cool the worktable of the first mounting stage.

4. The platform device as described in claim 3, characterized in that, Also includes: A first cooling medium piping supplyes the cooling medium to the second cooling section; and The second cooling medium piping supplies the cooling medium supplied to the second cooling section from the second cooling section to the first cooling section.

5. The platform device as described in claim 1, characterized in that: The second stage is levitated by the magnetic force between it and the first stage.

6. The mounting platform device as claimed in claim 1, characterized in that: The first mounting platform is capable of moving in the first direction on a guide rail arranged along the first direction.

7. The platform device as claimed in claim 1, characterized in that: The control device uses a vertical plane set on the worktable of the first mounting platform as a reference to measure the position of the second mounting platform at multiple points, and controls the tilt of the second mounting platform based on the measurement results.

8. The platform device as claimed in claim 7, characterized in that, Also includes: A linear scale is mounted on one of the vertical surface of the first mounting platform and the opposing surface of the second mounting platform that is opposite to the vertical surface. and A sensor, mounted on one of the vertical planes and the opposing plane, is used to read the linear scale. The control device controls the tilt of the second stage based on the measurement results of the sensor.

9. The platform device as claimed in claim 1, characterized in that: It also includes a strip-shaped reflector, which is set on the worktable of the second mounting stage. The position coordinates of the second stage are measured based on the laser light reflected from the strip-shaped mirror. The control device controls the position of the first or second platform based on the position coordinates.

10. The platform device as claimed in claim 1, characterized in that: It also includes cooling medium piping that supplies the cooling medium to the first cooling unit. The cooling medium piping is configured along the first direction and after the U-shaped bend, it is configured along the first direction, so that the part of the U-shaped bend is displaced as the first platform moves in the first direction.

11. The platform device as claimed in claim 1, characterized in that: It also includes cooling medium piping that supplies the cooling medium to the first cooling unit. The cooling medium piping is connected to the surface of the first mounting platform that is perpendicular to the first direction.

12. The platform device as claimed in claim 1, characterized in that: The first cooling unit is built into the workbench of the first mounting platform and includes a pipe having an inlet and outlet for the cooling medium.

13. The platform device as claimed in claim 1, characterized in that: The first cooling unit is mounted on the worktable of the first mounting platform and includes a radiator having a flow path for the cooling medium.

14. A charged particle beam device, characterized in that, include: Charged particle source; A chuck for carrying a sample irradiated by a particle beam emitted from the charged particle source; The stage device as described in any one of claims 1 to 13, is used to move the chuck; and A vacuum chamber, wherein the stage device is disposed in the vacuum chamber.

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