JP2001196021A - Target moving unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To conduct reliable braking and braking release. SOLUTION: A rail 22 for braking is mounted on a following member 20, and a parallel spring 24 is disposed so that its brake pads 29A and 29B sandwich a braking coil 22. Based on deformation of a piezo element, the braking pads 29A and 29B are moved in the direction of clamping the braking rail 22 when braking, while in the direction of parting from the braking rail 22 when releasing. The braking rail 22 and braking pads 29A and 29B are made to play roles as the electrode in addition so as to exert attraction force by giving potentials of mutually opposite polarities and repulsion force by giving potentials of different polarities.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a target moving device used for a radiation beam device such as a scanning electron microscope.

[0002]

2. Description of the Related Art A charged particle beam observation, inspection, analysis, and length measuring device is, for example, based on charged particles detected by irradiating a charged particle beam to a sample (target) on which an IC pattern is drawn. It performs pattern observation, inspection for pattern defects, etc., analysis of dust adhering to the material, and pattern length measurement. A charged particle beam drawing apparatus is for drawing an IC pattern by irradiating a charged particle beam onto a material (target) in which a resist is applied on a glass plate, for example. In recent years, it has become indispensable in the semiconductor manufacturing industry and the like. There is also a light beam device that performs observation, inspection, drawing, and the like of an IC pattern using a light beam such as a laser beam instead of charged particles.

As a target moving device in such a radiation beam device such as a charged particle beam device or a light beam device, a device capable of moving a target in a two-dimensional direction with high accuracy is usually used.

FIG. 1 shows an example of a target moving device. In the drawing, reference numeral 1 denotes a target chamber, which is not particularly shown. On the target chamber 1, for example, an electron beam device is used, for example, an electron gun and an electron beam from the electron gun for focusing on a material. An electron optical system column including a focusing lens and a deflection lens for causing the electron beam to be shot at a predetermined position on a target is provided.

[0005] In the figure, reference numeral 2 denotes a first stage for moving the target 3 in the X direction, on which the target 2 is placed via a holder 4. The first stage 2 includes a guide rail 6 provided on a second stage 5 for moving in the Y direction.
The guide rails 6A, 6B are movable by a drive source (for example, a servomotor) 8 provided outside the target chamber. 6B. Actually, the feed screw 7 is mounted on the first stage 2.
The first stage 2 can be moved in the X direction via the guide 9 without being screwed into the guide 9 approximately at the center of the guide 9 slid on the first stage 2. It is made. Since the guide 9 is provided in parallel with the Y direction, the first stage 2 is slidable with respect to the guide 9 in the Y direction. The guide 9 is provided on the bottom surface (base) of the target chamber 1 with guide rails 10A and 10B (guide rail 10B) placed in parallel in the X direction.
Are provided on the opposite side of the guide rail 10A with the stages 2 and 5 interposed therebetween, and are not shown).

The second stage 5 is slidably fitted on guide rails 11A and 11B placed on the bottom surface (base) of the target chamber 1 in parallel with the Y direction. A feed screw 12 is screwed into the second stage 5.
The drive source 13 provided outside the target chamber (for example,
(Servo motor).

In the target moving device having such a configuration, when the servo motor 8 is driven, the feed screw 7 rotates, and the guide 9 moves on the guide rails 10A and 10B. The movement of the guide causes the first stage 2 to move on the rails 6A and 6B, so that the target 3 moves by a predetermined amount in the X direction.

On the other hand, when the servo motor 13 is driven,
The feed screw 12 rotates, and the second stage 5
Since the first stage 2 mounted on the second stage 5 moves along the A and 11B, the first stage 2 mounted on the second stage 5 also moves integrally, and the target 3 moves a predetermined amount in the Y direction. During the movement in the Y direction, the guide 9 is stationary, and the first stage 2 is guided by the guide 9.

[0009]

As described above, the stage is moved by a predetermined amount by driving the feed screw by the motor.
When positioning the target, the following situation occurs.

For example, an electron beam apparatus that scans a pattern on a wafer on which an IC pattern is formed with an electron beam and displays a pattern image on a display screen based on image data based on secondary electrons detected by the scanning. Etc.
The stage is moved by driving the motor so that the region to be observed on the wafer is located at the center of the electron beam optical axis (the center of the electron beam scanning). After the motor is stopped, a predetermined region on the wafer is scanned with the electron beam. When the pattern image is displayed on the display device screen, a phenomenon in which the pattern image continues to flow, that is, a drift is observed. In particular, when a pattern image is displayed at a high magnification, the drift is large.

This drift appears remarkably immediately after stopping the first stage 2 after moving it by a predetermined amount in the X direction, or immediately after stopping the second stage 5 after moving it by a predetermined amount in the Y direction, After stopping, it gradually decreases over time.

This drift is considered to be due to the following process.

(A) When the stages 2 and 5 are moved, the feed screws 7 and 12 generate heat.

(B) Even if the servo motors 8 and 13 are stopped, the stage moves due to the thermal expansion of the feed screws 7 and 12 due to the heat generation.

(C) After the servomotors 8 and 13 are stopped, thermal equilibrium is reached with the passage of time, and the thermal expansion gradually stops and the drift stops.

However, such a drift causes the following problem.

If the pattern length measurement or the like is performed immediately after the servomotor is stopped or immediately after the stage is stopped, the measurement may be performed with extremely low accuracy due to the drift. In addition, if the image observation and length measurement are performed until the drift stops, that is, after a certain period of time after the motor is stopped, it takes a considerable amount of time to perform image observation and the like, and throughput is reduced. Getting worse.

The present invention solves such a problem and provides a novel target moving device.

[0019]

Means for Solving the Problems A target moving device according to the present invention is a target moving device configured to move a stage on which a target is mounted by rotating a feed screw connected to a shaft of a driving motor. A braking rail extending in the stage movement direction is attached, and at least one pair of braking pads opposed to sandwich the braking rail, and a direction in which the braking pad sandwiches the braking rail or A pad driving mechanism for driving in the opposite direction is attached to the base.

Further, the target moving device of the present invention is a target moving device configured to move a stage on which a target is mounted by rotating a feed screw connected to a shaft of a driving motor. At least one pair of braking rails, which are provided with an extended braking rail, and which face the braking rail in one groove opened at a portion facing each other with an internal deformation fulcrum as a boundary. A pad is mounted, an electrostrictive or magnetostrictive element is mounted in the other groove, and the braking pad is displaced in a direction sandwiching the braking rail or in the opposite direction based on the deformation of the electrostrictive or magnetostrictive element. And a spring member attached to the base.

[0021]

Embodiments of the present invention will be described below in detail with reference to the drawings.

FIGS. 2 and 3 show an example of a braking mechanism which is a main part of the target moving device of the present invention. FIG. 3 is a sectional view taken along line AA of FIG.

In FIG. 3, reference numeral 20 denotes a driven member, and reference numeral 21 denotes a fixed member. The driven member 20 is a stage itself or integrated with the stage, and corresponds to, for example, the first stage 2 or the second stage 5 in FIG.
The fixed member 21 corresponds to the second stage 5 when the driven member is the former first stage 2, and corresponds to the bottom surface (base) of the target chamber 1 when the driven member is the second stage 5.

A braking mechanism is provided between the driven member 20 and the fixed member 21. This braking mechanism is configured as follows.

Reference numeral 22 denotes a braking rail fixed to the driven member 20 via an insulating member 23, and is provided so as to be parallel to a guide rail for guiding the movement of the driven body 20. Reference numeral 24 denotes a parallel spring member having a rectangular parallelepiped shape as a whole, in which a U-shaped groove 25 is formed so as to be parallel to the braking rail 22. Grooves 27 and 28 are formed in the upper and lower portions of the central portion of the inner portion 26 of the U-shaped groove so as to be parallel to the braking rail 22, respectively. The inner diameter of the coil 22 is slightly larger than the outer diameter of the coil 22. The parallel spring member 24 is arranged so that the braking rail 22 is located at the center of the upper groove. Further, braking pads 29A and 29B are attached to both inner side portions of the upper groove 27 facing the braking rail 22 so that a gap is formed between the groove 27 and the braking rail 22. These braking pads 29A, 2
9B is a high dielectric member 30 around the electrodes 30A and 30B.
C, 30D. On the other hand, a piezo element 31 that is displaced in a direction perpendicular to the braking rail 22 is attached to an opening in the lower groove 28 in parallel with the braking rail. A tension spring 32 is mounted immediately above the piezo element (the tension spring 32 is not shown in FIG. 3). The facing portion between the upper groove 27 and the lower groove 28 is formed in a semi-cylindrical shape so that the boundary 33 between the upper groove 27 and the lower groove 28 becomes thinner toward the center. The boundary forms a hinge of a brake fulcrum.

On the other hand, two upper and lower portions 34A, 34B of both columnar portions 34, 35 outside the U-shaped groove 25,
35A and 35B are shaved from both sides in a semi-cylindrical shape in parallel with the braking rail 22, and form a spring-operated hinge so as to be displaceable in a direction perpendicular to the braking rail. ing.

In the drawing, reference numeral 36 denotes the braking rail 22.
And 37, a DC power supply for applying a DC voltage to the electrodes 30A, 30B of the brake pads 29A, 29B.

The operation in the case where the braking mechanism having such a structure is used in an apparatus as shown in FIG. 1 will be described. As described above, the driven member 20 corresponds to the first stage 2 and the second stage 5, and the fixed member 21 is the second stage 5 when the driven member is the first stage 2.
The second stage 5 corresponds to the bottom surface (base) of the target chamber 1.
Operations such as movement and stop of the stage 5 will be described, and description of the operation of the first stage 2 that performs the same operation will be omitted.

FIG. 4 is a timing chart. FIG. 4A shows the state of the stage synchronized with the movement and stop of the servomotor 8, that is, the timing of the movement and stop of the stage. FIG. 4B shows the state of the brake pads 29A and 29B. State, ie, timing of non-contact / contact with the braking rail 22, (c)
Is the timing of applying a voltage from the DC power supply 36 to the braking rail 22, (d) is the timing of applying a voltage from the DC power supply 37 to the brake pads 29A and 29B,
(E) shows a timing chart of the application of the voltage to the piezo element 31, and the following description of the operation follows this timing chart.

First, the voltage applied to the piezo element 31 from a piezo element power supply (not shown) is set to zero. Therefore,
The piezo element 31 is not deformed at all, and a gap is maintained between the braking rail 22 and the braking pads 29A and 29B. During the operation of the stage, the DC power supply 37 supplies the brake pads 29A and 2A.
A positive voltage is continuously applied to the 9B electrodes 30A and 30B. In this state, a positive voltage is applied from the DC power supply 36 to the braking rail 22. Then, the servo motor 13 is in a servo-on state, that is, feedback control (control for rotating the motor shaft by a predetermined amount, the rotation of the shaft is constantly monitored, and the difference between the predetermined rotation amount and the detected rotation amount is determined. Is performed, and an electric signal corresponding to a shaft rotation amount corresponding to the second stage movement amount is transmitted from the motor control device (not shown) to the servomotor 13 from the motor control device (not shown). . Then, the feed screw 12 connected to the shaft of the motor 13 rotates in synchronization with the rotation of the shaft of the motor 13, and the second stage 5 moves on the rails 11A and 11B, so that the target 3 moves by a predetermined amount in the Y direction. become.

Next, the servo motor 13 stops, and the second stage 5 also stops. At almost the same time as this stop (or immediately after the stop), a positive voltage is supplied from a piezo element power supply (not shown) to the piezo element 31. Apply voltage. Then, the piezo element 31 is deformed so that the right side extends in the + X direction and the left side expands in the −X direction from the center portion, and both pillar portions 34 below the boundary portion 33 in the inner portion 26 of the U-shaped groove 25. , 35 are displaced so as to spread in a direction perpendicular to the braking rail 22 with the boundary 33 as a fulcrum against the tensile force of the tension spring 32. That is, the right column 34 is displaced in the + X direction and the left column 35 is displaced in the −X direction, and the deformation causes the braking pads 29A and 29B to move with the boundary 33 as a fulcrum. Is displaced in the direction sandwiching. Therefore, there is no gap between the braking rail 22 and the braking pads 29A and 29B.
The braking pads 29A and 29B are in contact with the braking rail 22. At this time, the positive voltage applied from the piezo element power supply (not shown) to the piezo element 31 is further increased to increase the deformation of the piezo element 31, and the braking pads 29A,
Increase the compression force of 29B and complete the braking for stopping the stage. Then, in this state, a negative voltage is applied from the DC power supply 36 to the braking rail 22. In this manner, the state in which the braking pads 29A, 29B and the braking rail 22 are in contact (in this state, the braking pads 29A, 29B and the braking rail 22 sandwiching the high dielectric members 30C, 30D respectively) When a negative voltage is applied to the braking rail 22 in a state in which a capacitor is formed, a positive voltage is applied to the electrodes 30A and 30B of the braking pads 29A and 29B. The surface of the high dielectric portions 30C, 30D of the braking pads 29A, 29B covering the periphery of the brake pads 29A, 29B is charged, and the braking rail 22 and the braking pads 29A, 29B are coulombic (attractive).
Thereby, braking becomes stronger. Then, the servo motor 13 is set in a servo-off state so that the shaft of the servo motor 13 can be freely rotated by an external force. Then, while the second stage 5 having the braking effect is stopped, observation of an IC pattern in a certain area, length measurement, and the like based on electron beam scanning are performed.

Next, the servo motor 13 is set in a servo-on state, so that the shaft of the servo motor 13 cannot be freely rotated by an external force. Then, the voltage applied from the piezo element power supply (not shown) to the piezo element 31 is set to 0, and the piezo element 31 is returned to a state where it is not deformed. Then, in synchronization with the movement of the piezo element 31, the right column 34 is displaced in the -X direction and the left column 35 is displaced in the + X direction, and returns to the original state without displacement. As a result, the braking pads 29A and 29B are displaced in a direction away from the braking rail 22 with the boundary 33 as a fulcrum,
Braking rail 22 and braking pad 29
A gap is formed between A and 29B. In this state,
When a positive voltage is applied to the braking rail 22 from the DC power supply 36, a positive voltage is applied to the electrodes 30A and 30B of the braking pads 29A and 29B.
Braking rail 22 and braking pad 29
A and 29B repel each other due to Coulomb force (repulsive force), and the non-contact between the braking rail 22 and the braking pads 29A and 29 becomes more complete. In this state, an electric signal corresponding to the shaft rotation amount corresponding to the second stage movement amount is sent from the motor control device (not shown) to the servomotor 13. Then, the feed screw 12 connected to the shaft of the motor 13 rotates in synchronization with the rotation of the shaft of the motor 13, and the second stage 5 moves the rails 11 </ b> A, 11 </ b> A.
Since the target 3 moves on B, the target 3 moves by a predetermined amount in the Y direction.

Thereafter, a similar series of operations is repeated.

The above-mentioned playing pads 29A, 29
High dielectric member 3 covering each electrode 30A, 30B of B
As 0C and 30D, for example, a dielectric material having a strong dielectric constant of 9 l such as PZT (lead zirconate titanate) may be used. By using such a dielectric, the amount of charge of the high dielectric members 30C and 30D when the stage is stopped is further increased, whereby the braking rail 22 and the brake pads 29A and 29A when the stage is moved.
The repulsive force between the brake rails 9B and 9B can be increased, and as a result, non-contact between the braking rail 22 and the brake pads 29A and 29B during the movement of the stage can be ensured.

In the above example, a piezo element is used, but a magnetostrictive element may be used.

The present invention is not limited to a target moving device of a device for measuring or observing an IC pattern using an electron beam, but also a similar device using an ion beam,
The present invention can be used for a target moving device of a drawing device using an electron beam or an ion beam or a target moving device of a radiation beam device such as a similar device using a laser beam or the like.

As described above, according to the present invention, the stage is prevented from moving by using the braking mechanism when the motor or the stage is stopped. Movement does not occur. Therefore, even if pattern length measurement or the like is performed immediately after the motor or the stage is stopped, accurate length measurement or the like is performed. In addition, since highly accurate length measurement can be performed immediately after the motor or the stage is stopped, the throughput is improved.

Further, the braking mechanism of the present invention releases a plurality of braking pads in the direction sandwiching the braking rail attached to the stage when applying a brake, based on the deformation of the piezo element. At the time, since it is made to move in the direction away from the braking rail, soft braking and braking release can be performed. Therefore, no reaction force is generated during braking.
Even if the reaction force is generated, it is extremely small. Accordingly, the stage does not shake due to the reaction force, and the observation of the sample image, the length measurement, and the like are performed with high accuracy.

Further, the braking mechanism of the present invention further comprises:
The braking rail and the braking pad also serve as electrodes, and during braking, potentials of opposite polarities are applied to each other to exert an attractive force between each other to strengthen the contact between the braking rail and the braking pad. When the braking is released, potentials of different polarities are applied to each other and a repulsive force is applied between them to ensure that the braking rail and the braking pad do not contact each other. Release is surely performed. In addition, since the braking rail and the braking pad can be reliably brought into a non-contact state when the braking is released, the contact between the braking rail and the braking pad during the stage movement performed after the braking is released. There is no generation of dust based on

In the above example, the upper and lower portions of the two columnar portions 34, 35 outside the U-shaped groove 25 can be flexibly displaced in the direction perpendicular to the braking rail 22. As described above, the spring action hinge portions 34A, 34B, 35
Since the rails A and 35B are formed, when the braking rail 22 and the braking pads 29A and 29B repel each other, the braking rail 22 and the braking pads 29A and 29B when the stage is moved.
Is more reliably maintained.

[Brief description of the drawings]

FIG. 1 shows a schematic example of a target moving device.

FIG. 2 shows an example of a braking mechanism that is a main part of the target moving device of the present invention.

FIG. 3 is a sectional view taken along line AA of FIG. 2;

FIG. 4 is a timing chart related to the target moving device shown in FIGS. 2 and 3;

[Description of Signs] 1 Target chamber 2 First stage 3 Target 4 Holder 5 Second stage 6A, 6B, 10A, 10B, 11A, 11B Guide rails 7, 12 Feed screws 8, 13 Servo Motor 9 Guide 20 Guide member 21 Fixing member 22 Rail for shaking 23 Insulating member 24 Parallel spring member 25 U-shaped groove 27, 28 Groove 29A, 29B Breaking pad 30A, 30B ... Electrode 30C, 30D ... High dielectric member 31 ... Piezo element 32 ... Tension spring 33 ... Boundary part 34,35 ... Column part 36,37 ... DC power supply

Claims (7)

[Claims] In a target moving device configured to move a stage on which a target is mounted by rotating a feed screw connected to a shaft of a driving motor, a braking rail extending in a stage moving direction is attached to the stage. At least one pair of braking pads facing each other so as to sandwich the braking rail, and a pad driving mechanism for driving the braking pad in a direction to sandwich the braking rail or in the opposite direction are attached to the base. A target moving device characterized by being carried out. 2. A target moving device in which a stage on which a target is mounted is moved by rotation of a feed screw connected to a shaft of a driving motor, a braking rail extending in a stage moving direction is attached to the stage. At least one pair of opposing braking pads is mounted in one of the grooves opened at portions opposing each other with an internal deformation fulcrum as a boundary, and the other groove is provided. An electrostrictive or magnetostrictive element is mounted in the base, and based on a spring member formed so that the braking pad is displaced in the direction sandwiching the braking rail or in the opposite direction based on the deformation of the electrostrictive or magnetostrictive element. A target moving device characterized by being attached. 3. The braking rail is formed of a conductive member, and the braking pad is formed of a conductive member covered with a dielectric member. A voltage capable of applying a DC voltage to each conductive member. A source is provided.
3. The target moving device according to any one of claims 1 to 2. 4. The spring member has a rectangular parallelepiped shape, and has a U-shaped groove formed inside thereof so as to be parallel to the braking rail. At least one pair of braking pads which are opened at portions facing each other with the fulcrum portion as a boundary and which sandwich the braking rail in one groove are attached, and an electrostrictive or magnetostrictive element is provided in the other groove. The braking pad is attached so as to be displaced in a direction sandwiching the braking rail or in the opposite direction based on the deformation of the electrostrictive or magnetostrictive element. The hinge part having a spring action capable of being displaced in a direction perpendicular to the braking rail is formed at at least one position of the columnar part.
The target moving device according to claim 3. 5. The electrostrictive element or the magnetostrictive element is driven so as to be deformed so that the braking pad is displaced in a direction sandwiching the braking rail when the stage is stopped, and in an opposite direction when the stage is moved. The target moving device according to any one of claims 1 to 4, wherein 6. A voltage applied from the voltage source to the braking rail and the braking pad is such that voltages having the same polarity are applied when the stage is moved, and voltages having opposite polarities are applied when the stage is stopped. The target moving device according to any one of claims 3 to 5, wherein: 7. The target moving device according to claim 1, wherein the spring member is a parallel spring.