JP5090392B2 - Stage equipment - Google Patents

Description

  The present invention relates to a stage apparatus suitable as a sample stage of an electron microscope apparatus used for semiconductor inspection and evaluation in the field of semiconductor manufacturing.

  In the inspection of a pattern formed on a semiconductor wafer, a scanning electron microscope having a length measuring function (hereinafter referred to as a length measuring SEM) is used. In recent years, there is a tendency to shorten the time required for one measurement. Therefore, it is necessary to move the sample stage on which the wafer is mounted at high speed and high acceleration.

  When the sample stage is moved at a high speed and with a high acceleration, vibration is generated in the entire apparatus due to the reaction force. Such vibration not only adversely affects the secondary electron image of the length measurement SEM, but also causes an increase in settling time when positioning the sample stage. Therefore, it is necessary to suppress the vibration of the apparatus caused by the movement of the sample stage. For example, in a length measurement SEM, the vibration is limited to vibrations on the order of nanometers or less.

  Conventionally, several countermeasures against the apparatus vibration accompanying the movement of the sample stage are known. Among such techniques, there is a technique in which a moving body called a counter mass is provided to counteract reaction forces generated by a stage and suppress vibrations of the apparatus.

  In this technique, the reaction force accompanying the movement of the stage is completely canceled by operating the stage and the countermass so that the center of gravity of the counter mass coincides.

JP 2005-268268 A JP 2006-303131 A

  In the technique disclosed in Patent Document 1, it is necessary to arrange the counter mass at the same height as the stage, and the counter mass is installed near the stage. That is, it is necessary to arrange the counter mass in the sample chamber. However, it is difficult to install the conventional counter mass mechanism near the stage in the sample chamber.

  In the technique disclosed in Patent Document 2, the counter mass is arranged so as to surround the periphery of the stage. In this case, two counter masses are required for each of the first axis (referred to as the X axis) and the second axis (referred to as the Y axis) perpendicular thereto, and the entire apparatus drives four counter masses. Must have a motor. This complicates the apparatus configuration, increases the apparatus mass, and leads to the problem of increased cost of the stage apparatus.

  The objective of this invention is providing the stage apparatus which can suppress the vibration at the time of the movement of a stage, without complicating a structure.

  The stage device according to the present invention includes a stage mechanism, a counter mass mechanism, and a control device, and the control device includes a stage control unit that controls the stage mechanism and a counter mass control unit that controls the counter mass mechanism.

  In the stage apparatus according to the present invention, the movable plane of the counter mass and the movable plane of the stage are parallel to each other and spaced apart from each other.

  ADVANTAGE OF THE INVENTION According to this invention, the stage apparatus which can suppress the vibration at the time of the movement of a stage can be provided, without complicating a structure.

It is a figure which shows the whole structure of the example of the stage apparatus of this invention. It is a figure which shows schematic structure of the counter mass mechanism provided in the stage apparatus of this invention. It is a figure which shows schematic structure of the counter mass mechanism of the stage apparatus of this invention. It is a figure which shows schematic structure of the control apparatus of the stage apparatus of this invention. In the stage apparatus of this invention, it is a figure which shows an example of the time response waveform of the thrust command input into a counter mass at the time of stage movement. In the stage apparatus of this invention, it is a figure which shows an example of the time response waveform of the counter mass position at the time of a stage continuous movement.

  Hereinafter, a stage apparatus according to an embodiment of the present invention will be described in detail with reference to the drawings (FIGS. 1 to 6).

  FIG. 1 shows an example of a stage apparatus mounted on a scanning electron microscope (hereinafter referred to as a length measurement SEM) having a length measurement function according to the present invention. Here, the left-right direction in FIG. 1 is the X-axis direction, the direction perpendicular to the paper surface is the Y-axis direction, and the up-down direction in FIG. 1 is the Z-axis direction. The length measuring SEM of this example includes a sample chamber 11 and a cylindrical column 12 provided at a substantially center above the sample chamber 11. The column 12 is provided with an electron beam source, an electron beam optical system, and a secondary electron detection system. The length measuring SEM further includes a control device 4.

  The sample chamber 11 is installed on the base 10 via four vibration isolation members 14 and support legs 13. A stage mechanism 2 is provided inside the sample chamber 11. The stage mechanism 2 includes a stage base 21, a stage 22, a guide mechanism 23, and a stage drive mechanism 24. The stage 22 is driven by a stage drive mechanism 24. The stage 22 is moved along the X-axis direction or the Y-axis direction by the guide mechanism 23. The stage drive mechanism 24 may be configured by a linear motor or the like. The position of the stage 22 is measured by a stage position detection unit (not shown) and fed back to the control device 4. The stage position detection unit (not shown) may be configured by a laser interferometer, a linear scale, or the like.

  A counter mass mechanism 3 is provided on the lower surface of the sample chamber 11. The counter mass mechanism 3 includes a counter mass base 31, a counter mass guide mechanism 32, a counter mass drive mechanism 33, and a counter mass 34. The counter mass mechanism 3 further includes a counter mass position detection unit (not shown) that detects the position of the counter mass. The counter mass position detection unit may be configured by a laser interferometer, a linear scale, or the like. An evacuation unit (not shown) for evacuating the sample chamber 11 is provided on the lower surface of the sample chamber 11. Details of the counter mass mechanism 3 will be described later with reference to FIGS.

  An acceleration sensor 35 for detecting the acceleration of the sample chamber 11 is attached to the lower surface of the sample chamber 11. The acceleration sensor 35 is preferably capable of measuring three-axis acceleration of the XYZ axes. In this case, it is desirable to arrange the acceleration sensor 35 so that any two axes of the input axes of acceleration coincide with the X-axis direction and the Y-axis direction of the stage. In this example, the acceleration sensor 35 is mounted on the lower surface of the sample chamber 11. However, the acceleration sensor 35 is located at any position where vibration of the sample chamber can be detected, such as the side surface, upper surface of the sample chamber 11, or the inside of the sample chamber. May be installed. In this example, one acceleration sensor is used, but it is also effective to use two or more acceleration sensors.

  Further, the acceleration sensor 35 may be provided in the stage mechanism 2. That is, the acceleration sensor 35 can be provided at any position of the stage mechanism 2 unless it is mounted on the stage 22. In this case, the acceleration sensor 35 detects the acceleration of the stage mechanism 2, but the acceleration of the stage mechanism 2 and the acceleration of the sample chamber are substantially the same.

  The control device 4 includes a positioning control unit 41, a stage control unit 42, a counter mass control unit 44, and stage drive amplifiers 43 and 45. The positioning control unit 41 outputs a target position command for moving the stage 22 to the stage control unit 42. The stage control unit 42 calculates a thrust command for driving the stage 22 based on the position information of the stage 22 and a target position command fed back from a stage position detection unit (not shown). This thrust command is supplied to the stage drive mechanism 24 via the stage drive amplifier 43 to drive the stage 22. The thrust command calculated by the stage control unit 42 is also output to the counter mass control unit 44. The counter mass control unit 44 is measured by the position information of the counter mass 34 fed back from the counter mass position detection unit (not shown), the stage thrust command input from the stage control unit 42, and the acceleration sensor 35. A thrust command for driving the counter mass 34 is calculated using the acceleration information of the sample chamber 11. This thrust is supplied to the counter mass drive mechanism 33 via the counter mass drive amplifier 45 to drive the counter mass 34.

  For the sake of simplicity, FIG. 1 illustrates the case where the stage mechanism 2 and the counter mass mechanism 3 are driven along the X-axis direction, but the same applies to the case where they are driven along the Y-axis direction.

  The outline of the vibration preventing mechanism by the counter mass mechanism 3 of this example will be described. As illustrated, the stage 22 and the counter mass 34 both move along the XY plane. In other words, the movable surface of the stage 22 and the movable surface of the counter mass 34 are parallel to each other and are arranged apart from each other along the Z-axis direction. When the stage 22 accelerates or decelerates, a force F1 resulting from acceleration or deceleration acts as illustrated. This force F1 acts along the XY plane. A reaction force against the force F1 acts on the sample chamber 11 via the stage mechanism 2. Due to this reaction force, the sample chamber 11 vibrates. The vibration of the sample chamber 11 is basically one-dimensional or two-dimensional linear vibration along the XY plane. However, when the sample chamber 11 is regarded as a rigid body, the sample chamber 11 swings or oscillates R <b> 1 around the rotation axis passing through the vibration isolation member 14 or the support leg 13.

  In this example, the counter mass 34 is driven so that the thrust F 2 is generated in the counter mass 34. The vibration of the sample chamber 11 is canceled by the reaction force against the thrust F2.

  The force F1 applied to the stage 22 and the thrust F2 of the counter mass 34 have the same magnitude but act in opposite directions. The force F1 applied to the stage 22 and the thrust F2 of the counter mass 34 generate a couple. By this couple, not only the one-dimensional or two-dimensional linear vibration of the sample chamber 11 is canceled, but also the swinging motion or the rotational vibration of the sample chamber 11 is suppressed. Thus, according to the present invention, the linear vibration and the swinging motion or the rotational vibration of the sample chamber 11 are replaced by the couple acting on the stage 22 and the counter mass 34.

  When the stage 22 and the counter mass 34 are both at the origin, the counter mass 34 can be disposed vertically below the stage 22. At this time, the center of gravity of the counter mass 34 can be arranged on a vertical line passing through the center of gravity of the stage 22. This will be described in detail later.

  FIG. 2 shows the lower structure of the sample chamber 11. FIG. 2 is a perspective view of the sample chamber 11 as viewed obliquely from below. In FIG. 2, the base 10 is not shown for explanation. As shown in FIG. 2, the sample chamber 11 is installed on a base 10 (not shown) via four vibration isolation members 14 and support legs 13. A column 12 is provided on the sample chamber 11, and a counter mass mechanism 3 and a vacuum exhaust unit 6 are provided on the lower surface of the sample chamber 11. The vacuum exhaust unit 6 is attached near the center of the lower surface of the sample chamber 11. According to the present invention, the counter mass mechanism 3 has a substantially L shape. Therefore, the counter mass mechanism 3 can be disposed on the lower surface of the sample chamber 11 without disturbing the installation of the vacuum exhaust unit 6. That is, even if the vacuum exhaust unit 6 is installed near the center of the lower surface of the sample chamber 11, the counter mass mechanism 3 can be provided on the lower surface of the sample chamber 11.

  Here, an example in which the counter mass mechanism 3 is arranged on the lower surface of the sample chamber 11 has been shown, but the counter mass mechanism 3 may be installed on the upper surface of the sample chamber 11. A column 12 is provided on the sample chamber 11. However, the counter mass mechanism 3 has a substantially L shape. Therefore, the counter mass mechanism 3 can be provided on the upper surface of the sample chamber 11. Further, the counter mass mechanism 3 may be provided inside the sample chamber 11.

  The details of the counter mass mechanism 3 will be described with reference to FIG. FIG. 3 is a perspective view of the counter mass mechanism 3 provided on the lower surface of the sample chamber 11 as viewed obliquely from below. In FIG. 3, the lower surface of the sample chamber 11 is not shown for the sake of explanation. As shown, the X axis and the Y axis are taken along the lower surface of the sample chamber 11, and the Z axis is taken vertically upward.

  The counter mass mechanism 3 includes a counter mass base 311x, 311y (31 in FIG. 1) fixed to the lower surface of the sample chamber 11, and counter mass guide mechanisms 32x, 32y (mounted on the lower surface of the counter mass base 311x, 311y). 32), counter mass drive mechanisms 33x and 33y (33 in FIG. 1) mounted below them, and counter masses 341X, 341Y and 342 (34 in FIG. 1) mounted below them. Have.

  The counter mass base (31 in FIG. 1) is formed of a substantially L-shaped plate material, and has an X base 311x extending along the X-axis direction and a Y base 311y extending along the Y-axis direction.

  The counter mass guide mechanism (32 in FIG. 1) includes an X guide mechanism 32x and a Y guide mechanism 32y. The X guide mechanism 32x has a pair of parallel X rails 321x fixed to the Y base 311y, and an X sub-table 322x. The Y guide mechanism 32y has a pair of parallel Y rails 321y fixed to the X base 311x, and a Y subtable 322y. The X sub-table 322x is restrained by an X rail 321x extending along the X-axis direction, and is movable only along the X-axis direction. The Y sub-table 322y is restrained by a Y rail 321y that extends along the Y-axis direction, and is movable only along the Y-axis direction.

  The counter mass drive mechanism (33 in FIG. 1) includes an X drive mechanism 33x and a Y drive mechanism 33y. The X drive mechanism 33x has an X-axis motor movable element 332x and an X-axis motor stator 331x mounted on the Y sub-table 322y. The Y drive mechanism 33y includes a Y-axis motor movable element 332y and a Y-axis motor stator 331y mounted on the X sub-table 322x.

  The counter mass (34 in FIG. 1) includes an X counter mass member 341x, a Y counter mass member 341y, and a connecting member 342. The X counter mass member 341x and the connecting member 342 are connected via an X-axis motor stator 331x. The Y counter mass member 341y and the connecting member 342 are connected via a Y-axis motor stator 331y. The X-axis motor stator 331x and the Y-axis motor stator 331y function as a counter mass auxiliary member and are constituent elements of the counter mass. Like the counter mass base 31, the counter mass of this example is formed in a substantially L shape.

  The X drive mechanism 33x and the Y drive mechanism 33y may be configured by, for example, a linear motor. The linear motor basically includes a magnet and a coil, and generates a driving force by a magnetic attraction between them. In a normal linear motor, the mass of the stator is larger than the mass of the mover. Therefore, in this example, the motor stators 331x and 331y are used as counter mass auxiliary bodies. On the other hand, the motor movable elements 332x and 332y were mounted on the sub-tables 322x and 322y.

  Thus, in this example, motor stators 331x and 331y having a relatively large mass are used as counter mass auxiliary members. Accordingly, the masses of the counter mass members 341X and 341Y and the connecting member 342 can be reduced. For example, the motor stators 331x and 331y may be formed of an iron material having a relatively large mass such as cast iron. The motor stators 331x and 331y may be mounted on the sub tables 322x and 322y, and the motor movable elements 332x and 332y may be used as counter mass auxiliary members.

  When the counter masses 341X, 341Y, 342, 331x, and 331y are moved along the X-axis direction, the X drive mechanism 33x (331x and 332x) is driven. Thereby, a thrust Fx in the X direction is generated so that the X-axis motor movable element 332x moves in the X direction relative to the X-axis motor stator 331x. The thrust Fx moves the counter mass in the X-axis direction. When the counter mass moves in the X-axis direction, the Y-axis motor movable element 332y and the X sub-table 322x also move in the X-axis direction along the X rail 321x.

  When the counter masses 341X, 341Y, 342, 331x, and 331y are moved along the Y-axis direction, the Y drive mechanism 33y (331y and 332y) is driven. Thereby, a thrust Fy in the Y direction is generated so that the Y axis motor movable element 332y moves in the Y direction relative to the Y axis motor stator 331y. The thrust Fy moves the counter mass in the Y-axis direction. When the counter mass moves in the Y axis direction, the X axis motor movable element 332x and the Y sub table 322y also move in the Y axis direction along the Y rail 321y.

  According to this example, the counter masses 341X, 341Y, 342, 331x, and 331y are movable in the X-axis direction and the Y-axis direction. The mass of the counter mass mechanism can be reduced compared to

  Next, the position of the center of gravity of the counter mass of this example will be described. The counter mass of this example includes counter mass members 341X and 341Y, a connecting member 342, an X-axis motor stator 331x that functions as a counter mass auxiliary member, and a Y-axis motor stator 331y. The counter mass of this example is composed of an L-shaped structure formed by these components. Therefore, a triangle is drawn by connecting the centers of the components of the counter mass. The center of gravity of the counter mass is inside this triangle.

  In the counter mass of this example, the relative positions between the components of the counter mass are changed by changing the lengths of the X-axis motor stator 331x and the Y-axis motor stator 331y that function as counter mass auxiliary members. Changes. Thus, by changing the relative positions between the components of the counter mass, the position of the center of gravity of the counter mass can be selected to a desired position.

  Furthermore, the position of the center of gravity of the counter mass can be selected as a desired position by selecting the mass of the component of the counter mass to an appropriate value. In this example, the X-axis motor stator 331x and the Y-axis motor stator 331y are made of an iron-based material such as cast iron. Therefore, the masses of the X-axis motor stator 331x and the Y-axis motor stator 331y can be increased.

  According to this example, when the stage 22 (see FIG. 1) is at the origin and the counter mass is at the origin, the counter mass can be arranged below the stage 22 in the vertical direction. That is, the position of the center of gravity of the counter mass is selected so that the position of the center of gravity of the counter mass exists below the position of the center of gravity of the stage 22 in the vertical direction. That is, the position of the center of gravity of the counter mass is arranged on the vertical axis passing through the position of the center of gravity of the stage 22 (see FIG. 1).

  As described with reference to FIG. 2, according to this example, the counter mass mechanism 3 may be provided on either the lower surface or the lower surface of the sample chamber 11. A vacuum exhaust unit 6 is provided on the lower surface of the sample chamber 11, and a column 12 is provided on the upper surface of the sample chamber 11. However, the counter mass mechanism 3 is formed in an L shape. Therefore, even if the vacuum exhaust unit 6 or the column 12 is present, the barycentric position of the counter mass can be arranged vertically below the barycentric position of the stage 22 (see FIG. 1). Further, the counter mass mechanism 3 may be provided inside the sample chamber 11. Various components are also present inside the sample chamber 11. However, the counter mass mechanism 3 is formed in an L shape. Therefore, the barycentric position of the counter mass can be arranged vertically below the barycentric position of the stage 22 (see FIG. 1).

  FIG. 4 is a diagram showing a schematic configuration of an example of the control device of the stage apparatus of the present invention. The control device 4 includes a positioning control unit 41, a stage control unit 42, and a counter mass control unit 44. The stage mechanism 2 includes a stage 22, a stage drive mechanism 24, and a stage position detection unit 25. The counter mass mechanism 3 includes a counter mass 34, a counter mass drive mechanism 33, and a counter mass position detection unit 36.

  The positioning control unit 41 generates a target position command for moving the stage 22 to a preset target position according to a preset drive profile, and outputs it to the stage control unit 42.

  The stage control unit 42 includes a position control unit 421, a speed control unit 422, and a differentiator 423. The position control unit 421 inputs the position information of the stage 22 fed back from the stage position detection unit 25 and the target position command supplied from the positioning control unit 41, and calculates a position deviation which is the difference between the two. Further, a speed command is generated from the position deviation by PID control calculation or the like, and is output to the speed control unit 422. The differentiator 423 calculates the current speed of the stage 22 from the difference for each sample time of the position information of the stage 22 fed back from the stage position detection unit 25 and outputs it to the speed control unit 422. The speed control unit 422 inputs the speed command of the stage 22 and the current speed, and calculates a speed deviation that is the difference between the two. Further, a thrust command is generated from the speed deviation by PID control calculation or the like, and is output to the stage drive amplifier 43. The stage drive amplifier 43 generates a stage drive command from the thrust command and outputs it to the stage drive mechanism 24.

  The counter mass control unit 44 includes a position control unit 441, a speed control unit 442, a differentiator 443, an acceleration feedback calculation unit 444, a thrust feedforward coefficient unit 445, and an adder 446. Three thrust commands are supplied to the adder 446. The adder 446 calculates the sum of the three input thrust commands and outputs the sum to the counter mass drive amplifier 45 as the final thrust command. The counter mass drive amplifier 45 generates a counter mass drive command from the thrust command from the adder 446 and outputs it to the counter mass drive mechanism 33.

  Three thrust commands input to the adder 446 will be described. First, thrust commands used for thrust feedforward control will be described. A thrust command for the stage 22 is supplied from the speed control unit 422 of the stage control unit 42 to the counter mass control unit 44. The thrust feedforward coefficient unit 445 generates a thrust command for the counter mass 34 by multiplying the thrust command for the stage 22 by a coefficient. The coefficient multiplied by the thrust feedforward coefficient unit 445 is determined by the ratio of the mass of the stage 22 and the mass of the counter mass 34. Thus, a thrust command for the counter mass 34 proportional to the thrust command for the stage 22 is generated. In the thrust feedforward control, the counter mass 34 is driven so as to cancel the reaction force of the sample chamber 11 in the X-axis direction and the Y-axis direction caused by the movement of the stage 22.

  Next, thrust commands used for counter mass position control will be described. The position control unit 441 generates a speed command for the counter mass 34 by PID control calculation or the like from the position information of the counter mass 34 fed back from the counter mass position detection unit 36, and outputs it to the speed control unit 442. The differentiator 443 calculates the current speed of the counter mass 34 from the difference for each sample time of the position of the counter mass 34 fed back from the counter mass position detection unit 36, and outputs it to the speed control unit 442. The speed control unit 442 inputs a speed command for the counter mass 34 and a current speed, and calculates a speed deviation that is a difference between the two. Further, a thrust command for the counter mass 34 is generated from the speed deviation by PID control calculation or the like. Thus, in the counter mass position control, the counter mass 34 is driven so that the position of the counter mass 34 converges to the origin (stroke center). Thereby, the movable range (stroke) of the counter mass 34 can be greatly reduced. An example of position feedback control of the counter mass 34 is shown in FIG.

  A thrust command used for acceleration feedback control will be described. The acceleration feedback calculation unit 444 generates a thrust command that suppresses the vibration of the sample chamber 11 from the acceleration of the sample chamber 11 fed back from the acceleration sensor 35. The acceleration feedback calculation unit 444 may generate a thrust command by simply multiplying the fed back acceleration by a coefficient, but estimates the motion state (translation / rotation displacement / velocity) of the sample chamber 11 from the acceleration, and calculates it. A thrust command to be canceled may be calculated. Thus, in the acceleration feedback control, the counter mass 34 is driven so as to suppress the rotational vibration of the sample chamber 11 around the rotation axis in the X-axis and Y-axis directions that cannot be canceled by the thrust feedforward control.

  The adder 446 receives a negative input of a thrust command used for thrust feedforward control, a negative input of a thrust command used for counter mass position control, and a positive input of a thrust command used for acceleration feedback control. In this example, the counter mass 34 is controlled using the sum of the above three thrust commands as a final thrust command, but it is not always necessary to apply all three controls, and two or less control methods are applied. The counter mass 34 may be controlled.

  FIG. 5 is a diagram showing an example of a time response waveform of a thrust command supplied to the counter mass when the stage is moved in the stage apparatus of the present invention. The horizontal axis in FIG. 5 is time, and the vertical axis is thrust command. A dotted line graph 701 represents a time change of the thrust command when only the thrust feedforward control is applied, and a solid line graph 702 is applied with three controls of thrust feedforward control, acceleration feedback control, and counter mass position control. This represents the time change of the thrust command. A period A represents a period during which the counter mass 34 is moving, and a period B represents a period during which the counter mass 34 is stopped. That is, after the stop period B, the movement period A is reached, and then the stop period B is set. The movement period A of the counter mass 34 further includes an acceleration period a, a constant speed period b, and a deceleration period c.

  As shown by a dotted line graph 701, when only the thrust feedforward control is applied, a thrust command having a constant magnitude F is generated in the acceleration period a and the deceleration period c, but the stop period B and the constant speed period are generated. In b, the thrust command is zero. The thrust command for the acceleration period a and the thrust command for the deceleration period c are in opposite directions. The thrust generated by the counter mass 34 can cancel reaction forces in the X-axis direction and the Y-axis direction of the sample chamber 11 due to the movement of the stage.

  As shown in the graph of the solid line 702, when three controls are applied, a thrust command is generated in the acceleration period a and the deceleration period c, but this thrust command decreases slightly with time. ing. On the other hand, in the constant speed period b immediately after the acceleration period a, a small thrust in the direction opposite to the thrust command F applied in the acceleration period a is generated. Similarly, in the stop period B immediately after the deceleration period c, a small thrust in the direction opposite to the thrust command F applied in the deceleration period c is generated. These thrusts in the opposite directions converge to zero over time while fluctuating. This is due to acceleration feedback control and counter mass position control.

  FIG. 6 is a diagram showing an example of a time response waveform of the position of the counter mass when the stage is continuously moved in the stage apparatus according to the present invention. The horizontal axis of FIG. 6 is time, and the vertical axis is the position of the counter mass. FIG. 6 shows the response of the counter mass position when the stage 22 is continuously operated three times in the positive direction and three times in the negative direction with a constant movement amount L from the origin. A dotted line graph 801 indicates the position of the counter mass when a thrust command is generated by applying only the thrust feed forward control, and a solid line graph 802 indicates three controls: thrust feed forward control, acceleration feedback control, and counter mass position control. Represents the position of the counter mass when the thrust command is generated by applying. A period A represents a period during which the counter mass 34 is moving, and a period B represents a period during which the counter mass 34 is stopped. That is, the movement period A and the stop period B are alternately changed. The movement period A and the stop period B correspond to the movement period A and the stop period B in FIG. The movement period A of the counter mass 34 includes an acceleration period a, a constant speed period b, and a deceleration period c.

  As shown by the dotted line graph 801, when only the thrust feedforward control is applied, the position of the counter mass 34 changes by the distance L every time a thrust command is generated. The distance L is determined by the thrust feedforward coefficient 445. If the mass of the counter mass 34 is smaller than the mass of the stage 22, the moving distance L of the counter mass 34 becomes larger. Conversely, if the mass of the counter mass 34 is larger than the mass of the stage 22, The moving distance L becomes smaller. When the moving distance L of the counter mass 34 increases, the movable range (stroke) of the counter mass 34 needs to be increased.

  On the other hand, as shown by a solid line graph 802, when three controls of thrust feedforward control, acceleration feedback control, and counter mass position control are applied, the position of the counter mass 34 is the initial position, that is, near the origin. Is in the range. Therefore, the movable range of the counter mass 34 is small. In this case, an increase in the mass of the counter mass mechanism can be suppressed, and the size of the counter mass mechanism can be reduced. Therefore, the degree of freedom of installation of the counter mass mechanism can be increased.

  In this example, the position control of the counter mass 34 is always set to the target position, but if the movement amount and the movement direction of the stage 22 at the next movement are determined in advance, the position control unit of the counter mass control unit 44 is determined. Position control 441 may be performed at a position where a stroke can be secured in a specific direction in preparation for the next movement. As described above, in the present invention, when the stage 22 (see FIG. 1) is at the origin and the counter mass is at the origin, the counter mass is below the stage 22 in the vertical direction. Therefore, even if the stage 22 moves, the counter mass can always be arranged below the stage 22 in the vertical direction.

  As described above, the stage apparatus of the present invention can improve the degree of freedom of arrangement of the counter mass mechanism while suppressing the complexity of the counter mass mechanism and the increase in the mass of the counter mass mechanism, as well as the vibration suppressing effect. Can be achieved.

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

DESCRIPTION OF SYMBOLS 2 ... Stage mechanism, 3 ... Counter mass mechanism, 4 ... Control apparatus, 6 ... Vacuum exhaust unit, 10 ... Base, 11 ... Sample chamber, 12 ... Column, 13 ... Support leg, 14 ... Anti-vibration member, 21 ... Stage base , 22 ... stage, 23 ... stage guide mechanism, 24 ... stage drive mechanism, 32 ... counter mass guide mechanism, 33 ... counter mass drive mechanism, 34 ... counter mass, 35 ... acceleration sensor, 41 ... positioning control unit, 42 ... stage Control unit 43... Stage drive amplifier 44. Counter mass control unit 45. Counter mass drive amplifier

Claims (20)

A stage mechanism including a stage movable along at least one axial direction, a stage drive mechanism that drives the stage, and a stage position detection unit that detects the position of the stage, and a counter movable along at least one axial direction A counter mass mechanism including a mass, a counter mass drive mechanism that drives the counter mass, and a counter mass position detection unit that detects the position of the counter mass; a stage control unit that controls the stage mechanism; and a control of the counter mass mechanism A control device having a counter mass control unit to
The counter mass is an L-shaped structure, and the movable plane of the counter mass and the movable plane of the stage are parallel to each other and are spaced apart from each other. The stage apparatus according to claim 1, wherein
The counter mass includes a first counter mass member, a second counter mass member, a connecting member, a first counter mass auxiliary member connecting the first counter mass member and the connecting member, and the first counter mass member. 2 counter mass members and a second counter mass auxiliary member connecting the connecting member, wherein the first counter mass member, the first counter mass auxiliary member and the connecting member are in one axial direction. The second counter mass member, the second counter mass auxiliary member, and the connecting member are arranged along the other axial direction, thereby being configured in an L shape. Stage device. The stage apparatus according to claim 2, wherein
4. The stage apparatus according to claim 3, wherein the first and second counter mass auxiliary members are made of a material having a larger specific gravity than materials of the front first and second counter mass members. The stage apparatus according to claim 1, wherein
The counter mass drive mechanism is constituted by a linear motor having a stator and a mover, and a stage device having a larger mass among the stator and the mover is used as a component of the counter mass. The stage apparatus according to claim 1, wherein
A stage apparatus, wherein the center of gravity of the counter mass is arranged on a vertical line passing through the center of gravity of the stage when the stage and the counter mass are arranged at the origin. The stage apparatus according to claim 1, wherein
The stage device, wherein the counter mass control unit performs thrust feedforward control for generating a thrust command for the counter mass proportional to a thrust command for the stage calculated by the stage control unit.   7. The stage apparatus according to claim 6, wherein the thrust command for the counter mass is obtained by multiplying the thrust command for the stage by a ratio of the mass of the stage and the mass of the counter mass. The stage apparatus according to claim 1, wherein
The stage apparatus, wherein the counter mass control unit performs counter mass position control for driving the counter mass so that the position of the counter mass converges to an origin. The stage apparatus according to claim 8, wherein
In the counter mass position control, a speed command for the counter mass is generated by PID control calculation from the position information of the counter mass fed back from the counter mass position detection unit, and the current value of the counter mass is determined from the position information of the counter mass. A stage device that calculates a position and generates a thrust command for the counter mass based on a deviation between the speed command and the current speed. The stage apparatus according to claim 1, wherein
The stage mechanism has an acceleration sensor for measuring acceleration,
The stage device is characterized in that the counter mass control unit performs acceleration feedback control for generating a thrust command for the counter mass so as to suppress vibration of the stage mechanism from the acceleration fed back from the acceleration sensor. A sample chamber configured to be evacuated, a column provided on the sample chamber, an electron beam source and an electron beam optical system provided in the column, and an X axis and a Y axis orthogonal to each other In an electron microscope apparatus having an axis and a Z axis,
A stage mechanism including a stage movable along the X axis and the Y axis, a stage drive mechanism for driving the stage, and a stage position detection unit for detecting the position of the stage, and movable along the X axis and the Y axis A counter mass mechanism including a counter mass, a counter mass drive mechanism for driving the counter mass, and a counter mass position detection unit for detecting the position of the counter mass; a stage control unit for controlling the stage mechanism; and the counter mass mechanism A control device having a counter mass control unit for controlling
The electron microscope apparatus, wherein the counter mass is an L-shaped structure, and the movable plane of the counter mass and the movable plane of the stage are parallel to each other and spaced apart from each other. The electron microscope apparatus according to claim 11,
The counter mass includes a first counter mass member, a second counter mass member, a connecting member, a first counter mass auxiliary member connecting the first counter mass member and the connecting member, and the first counter mass member. 2 counter mass members and a second counter mass auxiliary member for connecting the connecting member, wherein the first counter mass member, the first counter mass auxiliary member and the connecting member are along the X-axis direction. The second counter mass member, the second counter mass auxiliary member, and the connecting member are arranged along the Y-axis direction, and are thus configured in an L shape. Microscope device. The electron microscope apparatus according to claim 11,
The electron microscope apparatus, wherein the counter mass mechanism is installed on a lower surface or an upper surface of the sample chamber. The electron microscope apparatus according to claim 11, further comprising an evacuation unit that evacuates the sample chamber.
The electron microscope apparatus, wherein the vacuum exhaust unit and the counter mass mechanism are provided on a lower surface of the sample chamber. The electron microscope apparatus according to claim 11,
The sample chamber is provided with an acceleration sensor for measuring acceleration,
The counter mass control unit is configured to generate a thrust feedforward control for generating a thrust command for the counter mass proportional to a thrust command for the stage calculated by the stage control unit, so that the position of the counter mass converges to the origin. , At least one of counter mass position control for driving the counter mass and acceleration feedback control for generating a thrust command for the counter mass so as to suppress vibration of the stage mechanism from the acceleration fed back from the acceleration sensor. An electron microscope apparatus characterized by being performed. The electron microscope apparatus according to claim 15, wherein
In the thrust feedforward control, the thrust command for the counter mass is obtained by multiplying the thrust command for the stage by a ratio of the mass of the stage and the mass of the counter mass. The electron microscope apparatus according to claim 15, wherein
In the counter mass position control, a speed command for the counter mass is generated by PID control calculation from the position information of the counter mass fed back from the counter mass position detection unit, and the current value of the counter mass is determined from the position information of the counter mass. An electron microscope apparatus that calculates a position and generates a thrust command for the counter mass based on a deviation between the speed command and the current speed. The electron microscope apparatus according to claim 15, wherein
The acceleration feedback control suppresses rotational vibrations about rotation axes in the X-axis and Y-axis directions that cannot be canceled out by the thrust feedforward control. A stage mechanism including a stage movable along at least one axial direction, a stage drive mechanism that drives the stage, and a stage position detection unit that detects the position of the stage, and a counter movable along at least one axial direction A counter mass mechanism including a mass, a counter mass drive mechanism that drives the counter mass, and a counter mass position detection unit that detects the position of the counter mass; a stage control unit that controls the stage mechanism; and a control of the counter mass mechanism A control device having a counter mass control unit for measuring, and an acceleration sensor for measuring acceleration,
The counter mass is an L-shaped structure, and the movable plane of the counter mass and the movable plane of the stage are parallel to each other and spaced apart from each other.
The counter mass control unit is configured to generate a thrust feedforward control for generating a thrust command for the counter mass proportional to a thrust command for the stage calculated by the stage control unit, so that the position of the counter mass converges to the origin. , At least one of counter mass position control for driving the counter mass and acceleration feedback control for generating a thrust command for the counter mass so as to suppress vibration of the stage mechanism from the acceleration fed back from the acceleration sensor. The stage apparatus characterized by performing. The stage device according to claim 19,
A stage apparatus, wherein the center of gravity of the counter mass is arranged on a vertical line passing through the center of gravity of the stage when the stage and the counter mass are arranged at the origin.

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