JP7619805B2 - ROBOT SYSTEM AND IMAGING METHOD - Google Patents

Description

The present invention relates to acquiring information using an imaging device installed in a robot.

Conventionally, a configuration in which an imaging device is provided on a robot for transporting substrates has been known. Patent Document 1 discloses this type of configuration.

The semiconductor wafer grinding device of Patent Document 1 includes a wafer transport robot and a reflecting mirror. A camera serving as an imaging means is mounted on the wafer transport robot. The reflecting mirror is positioned at a 45-degree incline. When a wafer is stored protruding from the opening of the wafer cassette, the reflecting mirror displays the wafer in a state that allows it to be imaged by the camera. The image displayed on the reflecting mirror is captured by the camera and analyzed by a discrimination means, making it possible to detect the presence or absence of a wafer protruding from the opening before it is removed. Patent Document 1 claims that this makes it possible to prevent damage to semiconductor wafers.

Patent No. 5295720

In the configuration of Patent Document 1, the reflecting mirror only reflects the wafers stored in the wafer cassette. Therefore, a configuration that allows the robot to handle substrates more efficiently was needed.

The present invention has been made in consideration of the above circumstances, and its purpose is to obtain useful information about a robot using an imaging device with a compact configuration.

The problem that the present invention aims to solve is as described above. Next, we will explain the means for solving this problem and its effects.

According to a first aspect of the present invention, there is provided a robot system having the following configuration. That is, the robot system includes a mirror, a robot, and an imaging device. The robot has a hand that holds a substrate. The imaging device is provided on the robot so that the imaging angle is horizontal. The robot is capable of changing the position of the hand relative to the mirror. The mirror is disposed at an incline with respect to a horizontal plane. With the robot inserting at least a part of the hand into a space below the mirror, the imaging device images the upper surface side of the hand through the mirror. The robot system includes an aligner device that adjusts the orientation of the set substrate. The imaging device images the substrate held on the upper surface side of the hand through the mirror. The operation of the aligner device for adjusting the orientation of the substrate changes based on the image captured by the imaging device.

According to a second aspect of the present invention, there is provided the following imaging method for a robot system including a robot, an imaging device, and an aligner device . The robot has a hand that holds a substrate. The imaging device is provided on the robot so that the imaging angle is horizontal. The aligner device adjusts the orientation of the set substrate. The imaging method includes an insertion step and an imaging step. In the insertion step, the robot inserts at least a part of the hand into a space below a mirror that is arranged at an angle with respect to a horizontal plane. In the imaging step, the imaging device images the upper surface side of the hand through the mirror. In the imaging step, the imaging device images the substrate held on the upper surface side of the hand through the mirror. The operation of the aligner device for adjusting the orientation of the substrate is changed based on the image captured by the imaging device.

This allows the imaging device, which is horizontally oriented, to capture a wide area above the hand. This makes it possible to easily obtain information about the hand and other parts while keeping the robot's vertical size small. In addition, by changing the operation of the aligner device according to the situation, the orientation of the substrate can be adjusted efficiently.

According to the present invention, it is possible to obtain useful information about a robot using an imaging device with a compact configuration.

1 is a perspective view showing a configuration of a robot system according to an embodiment of the present invention. FIG. FIG. 13 is a diagram showing a state in which the robot holds a substrate. FIG. FIG. 2 is a block diagram showing the electrical configuration of the robot system. 5A and 5B are schematic diagrams illustrating an operation of detecting a notch of a wafer by an aligner device. 11 is a flowchart showing control of photographing by a camera and adjustment of the orientation of a wafer.

Next, an embodiment of the present invention will be described with reference to the drawings. FIG. 1 is a perspective view showing the configuration of a robot system 100 according to one embodiment of the present invention. FIG. 2 is a perspective view showing the configuration of a robot 1. FIG. 3 is a block diagram showing the configuration of a portion of the robot system 100.

The robot system 100 shown in FIG. 1 is a system that causes a robot 1 to perform work in a work space such as a clean room.

The robot system 100 includes a robot 1, an aligner device 4, and a controller (control device) 5.

The robot 1 functions, for example, as a wafer transfer robot that transports a wafer (substrate) 2 stored in a storage container 8. In this embodiment, the robot 1 is realized by a SCARA type horizontal articulated robot. SCARA is an abbreviation for Selective Compliance Assembly Robot Arm.

The wafer 2 transported by the robot 1 is formed in the shape of a circular thin plate. A notch (concave) 2a is formed on the outer periphery of the wafer 2. The notch 2a indicates the crystal orientation of the semiconductor wafer. Instead of the notch 2a, an orientation flat (flat portion) may be formed on the wafer 2.

As shown in FIG. 2, the robot 1 includes a hand (holding unit) 10, a manipulator 11, and an attitude detection unit 12.

The hand 10 is a type of end effector, and is generally V- or U-shaped in plan view. The hand 10 is supported at the tip of the manipulator 11 (specifically, the second link 16 described below). The hand 10 rotates around a third axis c3 that extends in the vertical direction relative to the second link 16. In plan view, the hand 10 is formed to be linearly symmetrical with respect to an axis passing through the third axis c3. Figure 3 shows the axis of symmetry A1 of the hand.

The hand 10 is configured as an edge grip type hand. As shown in FIG. 3 etc., a plurality of edge guide parts 6 for holding the wafer 2 are provided on both the tip side and the base side of the hand 10. The edge guide parts 6 can come into contact with the outer peripheral surface of the disk-shaped wafer 2.

A pressing member 7 is provided at the base of the hand 10. The pressing member 7 can move along the symmetry axis A1 of the hand 10. An actuator (not shown) built into the hand 10 is connected to the pressing member 7. The actuator may be configured as an air pressure cylinder in this embodiment, although any configuration is possible. The air pressure cylinder is connected to a compressed air supply source through a pipe (not shown) that passes through the inside of the manipulator 11.

By supplying compressed air to the pneumatic cylinder, the pressing member 7 can be displaced toward the tip of the hand 10. The pressing member 7 comes into contact with the outer peripheral surface of the wafer 2 placed on the hand 10 and presses the wafer 2 toward the tip of the hand 10. As a result, the pressing member 7 can hold the wafer 2 between itself and the edge guide portion 6 on the tip side of the hand 10.

A camera 3 is provided at the base of the hand 10 as an imaging device. The camera 3 is fixed integrally to the hand 10 so that it can capture images of the surroundings at a horizontal angle along the axis of symmetry A1 of the hand 10. The lens of the camera 3 is located above the top surface of the hand 10. The camera 3 is electrically connected to the controller 5 of the robot 1.

As shown in FIG. 2, the manipulator 11 mainly comprises a base 13, a lifting shaft 14, a first link 15, and a second link 16.

The base 13 is fixed to the ground (e.g., the floor of a clean room). The base 13 functions as a base member that supports the lift shaft 14.

The lifting shaft 14 moves up and down relative to the base 13. This lifting and lowering allows the height of the first link 15, the second link 16, and the hand 10 to be changed.

The first link 15 is supported on the upper part of the lift shaft 14. The first link 15 rotates around a first axis c1 that extends in the vertical direction relative to the lift shaft 14. This allows the position of the first link 15 to be changed within the horizontal plane.

The second link 16 is supported at the tip of the first link 15. The second link 16 rotates around a second axis c2 that extends in the vertical direction relative to the first link 15. This allows the position of the second link 16 to be changed within the horizontal plane.

The manipulator 11 is provided with multiple drive motors (not shown). The drive motors can rotate the first link 15, the second link 16, and the hand 10 in a horizontal plane. The drive motors can also raise and lower the lift shaft 14. The drive motors can be configured as electric motors, for example.

The aligner device 4 is, for example, a pre-aligner (wafer aligner). As shown in FIG. 1, the aligner device 4 includes a rotating table (rotating unit) 41 and a line sensor (sensor) 42.

The turntable 41 can rotate the wafer 2 by an electric motor (not shown) or the like. The turntable 41 rotates with the wafer 2 placed on it. The direction of rotation of the turntable 41 can be changed as necessary by switching the direction of rotation of the electric motor or the like. The turntable 41 is formed, for example, in a cylindrical shape as shown in FIG. 1. However, the shape of the turntable 41 is not limited.

The line sensor 42 is composed of, for example, a transmission type sensor having a light-projecting section and a light-receiving section. The light-projecting section and the light-receiving section face each other and are arranged at a predetermined interval in the vertical direction. The line sensor 42 projects detection light through the light-projecting sections arranged in the radial direction of the rotating table 41, and receives the detection light through the light-receiving section provided below the light-projecting sections. The detection light can be, for example, laser light. When the wafer 2 is placed on the rotating table 41, its outer edge is positioned between the light-projecting section and the light-receiving section.

The line sensor 42 is electrically connected to the controller 5 of the robot 1. The line sensor 42 transmits the detection result of the light receiving part to the controller 5. Although details will be described later, the change in the detection result of the light receiving part when the turntable 41 is rotated corresponds to the shape of the outer edge of the wafer 2. From the shape of this outer edge, the orientation of the notch 2a of the wafer 2 can be detected. The line sensor 42 is not limited to a transmission type sensor, and may be composed of, for example, a reflection type sensor.

As shown in FIG. 1, the mirror 9 is provided at a position to the side of the aligner device 4. The hand 10 can be inserted into the space directly below the mirror 9. When the hand 10 is inserted downward, the mirror 9 is arranged at an angle that becomes lower toward the tip of the hand 10.

With the hand 10 inserted in a predetermined position below the mirror 9 as shown in Figure 4, the wafer 2 reflected on the mirror 9 can be photographed by the camera 3. It is preferable to position the hand 10 in a position that allows the entire wafer 2 reflected on the mirror 9 (in other words, the entire circumference) to be included in the field of view of the camera 3. In this way, no matter where the notch 2a is located on the wafer 2, the notch 2a can be reliably photographed by the camera 3.

In the example of Figure 4, the wafer 2 is inserted so that the entire wafer 2 overlaps the mirror 9 in a plan view. This makes it easy to include the entire circumference of the wafer 2 in the field of view of the camera 3. The degree of inclination of the mirror 9 is arbitrary, but it is preferable to make the inclination angle α with respect to the horizontal plane smaller than 45°, so that a wide area around the hand 10 can be reflected with a small mirror 9.

As shown in FIG. 3, the controller 5 includes a transport control unit 51, an image analysis unit 52, an aligner control unit 53, and an orientation acquisition unit 54. The controller 5 is configured as a known computer including a CPU, ROM, RAM, an auxiliary storage device, etc. The auxiliary storage device is configured as, for example, an HDD, SSD, etc. The auxiliary storage device stores a robot control program, etc. for implementing the imaging method of the present invention. Through cooperation of these hardware and software, the controller 5 can operate as the transport control unit 51, the image analysis unit 52, the aligner control unit 53, the orientation acquisition unit 54, etc.

The transport control unit 51 outputs command values to the respective drive motors that drive each part of the robot 1 described above in accordance with a predetermined operating program or movement commands input by the user, and controls the motors to move the hand 10 to a predetermined command position.

The image analysis unit 52 analyzes the image captured by the camera 3. The image analysis unit 52 can obtain the direction in which the notch 2a faces by detecting the position of the notch 2a of the wafer 2 that appears in the image data. The orientation of the notch 2a is precisely measured later by the aligner device 4. Therefore, it is sufficient for the image analysis unit 52 to be able to roughly obtain the orientation of the notch 2a. The image analysis can be performed, for example, using known pattern recognition.

The aligner control unit 53 controls the rotation/stop of the turntable 41 provided in the aligner device 4, detection/stop of detection of the line sensor 42, etc.

As described above, the orientation acquisition unit 54 obtains the direction in which the notch 2a formed on the wafer 2 faces based on the detection results from the line sensor 42.

In this embodiment, the transport control unit 51 controls the robot 1 so that the orientation of the wafer 2 when photographed by the camera 3 via the mirror 9 matches the orientation of the wafer 2 when it is set in the aligner device 4.

Figure 6 shows the mirror 9 and the aligner device 4 in a plan view. In the aligner device 4, the line sensor 42 is located at the 0 o'clock position in Figure 6.

As shown in FIG. 6(a), if the notch 2a is located near the 2 o'clock position in a plan view when photographed by the camera 3, the line sensor 42 can detect the notch 2a in a shorter time if the turntable 41 in the aligner device 4 is rotated counterclockwise than if it is rotated clockwise.

On the other hand, as shown in FIG. 6(b), if the notch 2a is located near the 9 o'clock position in a plan view when photographed by the camera 3, the line sensor 42 can detect the notch 2a in a shorter time if the turntable 41 in the aligner device 4 is rotated clockwise than if it is rotated counterclockwise.

In this way, the controller 5 controls the rotation direction of the turntable 41 in the aligner device 4 to vary based on the image captured by the camera 3. This effectively reduces the processing time required when the aligner device 4 precisely adjusts the orientation of the wafer 2.

In this embodiment, the orientation of the notch 2a can be roughly grasped based on the results of photographing the notch 2a by the camera 3. Therefore, in an angle region where it is known in advance that the notch 2a will not be detected by the line sensor 42, the aligner device 4 can control the rotation table 41 to rotate faster than usual. In this case, the processing time can be further shortened.

The controller 5 may cause the aligner device 4 to adjust the orientation of the wafer 2 based only on the orientation of the notch 2a acquired from the results of photographing the notch 2a by the camera 3. That is, precise detection of the notch 2a by the line sensor 42 may be omitted. In this case, the line sensor 42 can be omitted from the aligner device 4. In general, the detection accuracy of the orientation of the notch 2a by the camera 3 is not higher than that of the line sensor 42. However, depending on the application, such rough sensing may be sufficient.

While the camera 3 is attached to the hand 10, the mirror 9 is not attached to the hand 10. The mirror 9 is fixedly positioned at a location a short distance away from the robot 1, and the hand 10 can be moved close to the mirror 9 to photograph the wafer 2 only when necessary. This makes it possible to obtain a lightweight and compact hand 10.

The camera 3 is mounted on the hand 10 so that it can take pictures at a horizontal angle, making it easy to make the hand 10 compact in the thickness direction (vertical direction). In other words, even if the camera 3 is mounted, the overall height of the hand 10 can be kept small.

The camera 3 can not only photograph the wafer 2 through the mirror 9, but also photograph various locations. For example, the inside of the storage container 8 can be photographed with the camera 3. Therefore, the camera 3 can be used efficiently for monitoring the surroundings, etc. The camera 3 is attached in the same orientation as the tip of the hand 10, so the position and attitude of the camera 3 can be controlled in the same way as the position and attitude of the hand 10 are controlled. Therefore, control for photographing is easy.

The camera 3 can also perform constant monitoring. This allows, for example, early detection of abnormalities in the wafer 2 and/or the hand 10. As described above, the camera 3 is mounted on the hand 10, so vibrations occurring in members such as the wafer 2 held by the hand 10 are the same as those occurring in the camera 3. Therefore, in the image captured by the camera 3, members such as the wafer 2 held by the hand 10 are clearly visible.

Next, referring to FIG. 7, the control of photographing by the camera 3 and adjusting the orientation of the wafer 2 will be described.

First, the transport control unit 51 of the controller 5 appropriately controls the drive motor of the robot 1 to, for example, remove the wafer 2 from the storage container 8 using the hand 10. The transport control unit 51 controls the robot 1 to insert the wafer 2 held by the hand 10 together with the hand 10 below the mirror 9 (step S101). This state is shown in Figure 4.

Next, the camera 3 captures an image of the wafer 2 reflected in the mirror 9 (step S102). The image data acquired by the camera 3 is output to the image analysis unit 52 of the controller 5.

The image analysis unit 52 analyzes the input image data to obtain the phase of the notch 2a and stores it in a storage device provided in the controller 5 (step S103).

Then, the transport control unit 51 controls the robot 1 to move the hand 10, transport the wafer 2 to the aligner device 4, and place it on the rotating table 41 (step S104).

The controller 5 determines whether the phase of the notch 2a obtained by the image analysis in step S103 is greater than or equal to 0 o'clock and less than 6 o'clock in FIG. 6 (step S105).

As shown in FIG. 6(a), if the phase of notch 2a is between 0 o'clock and 6 o'clock, the aligner control unit 53 rotates the turntable 41 counterclockwise (step S106). As shown in FIG. 6(b), if the phase of notch 2a is not between 0 o'clock and 6 o'clock, the aligner control unit 53 rotates the turntable 41 clockwise (step S107). In either case, the rotation of the turntable 41 continues until the line sensor 42 detects the notch 2a.

When the notch 2a of the wafer 2 is detected, the orientation of the turntable 41 is adjusted appropriately based on the rotation phase of the turntable 41 at the time of detection (step S108). As a result, the orientation of the wafer 2 can be adjusted to the desired orientation.

Then, the transport control unit 51 controls the robot 1 so that the hand 10 removes the wafer 2 from the aligner device 4 and transports it to a specified destination (step S109).

As described above, the robot system 100 of this embodiment includes a mirror 9, a robot 1, and a camera 3. The robot 1 has a hand 10 that holds a wafer 2. The camera 3 is provided on the robot 1 so that the shooting angle is horizontal. The robot 1 can change the position of the hand 10 relative to the mirror 9. The mirror 9 is disposed at an angle relative to the horizontal plane. With the robot 1 inserting at least a portion of the hand 10 into the space below the mirror 9, the camera 3 shoots an image of the upper surface of the hand 10 through the mirror 9.

This allows the horizontally-oriented camera 3 to capture a wide range of images of the horizontal surface above the hand 10. This makes it easy to obtain information about the hand and other parts with a configuration that limits the robot's vertical size.

In the robot system 100 of this embodiment, the robot 1 is configured as a horizontal articulated robot.

The configuration in which the camera 3 is positioned so that the shooting angle is horizontal and captures the image of the wafer 2 through the tilted mirror 9 is particularly suitable for a horizontal articulated robot that transports the wafer 2 in a horizontal position.

The robot system 100 of this embodiment is equipped with an aligner device 4 that adjusts the orientation of the set wafer 2. The camera 3 captures an image of the wafer 2 held on the upper side of the hand 10 via a mirror 9. The operation of the aligner device 4 to adjust the orientation of the wafer 2 changes based on the image captured by the camera 3.

This allows the operation of the aligner device 4 to be changed according to the situation, making it possible to efficiently adjust the orientation of the wafer 2.

In the robot system 100 of this embodiment, the wafer 2 is disk-shaped with a notch 2a formed on its outer periphery. The aligner device 4 includes a rotating table 41 and a line sensor 42. The rotating table 41 rotates the substrate. The line sensor 42 detects the notch 2a at a constant phase relative to the center of rotation of the rotating table 41. The aligner device 4 changes the direction in which the rotating table 41 rotates the wafer 2 in order to detect the notch 2a with the line sensor 42, based on the position of the notch 2a photographed by the camera 3.

This allows the angle at which the turntable 41 is rotated in the aligner device 4 to search for the notch 2a of the wafer 2 to be reduced. Therefore, the orientation of the wafer 2 can be adjusted efficiently.

In addition, in the robot system 100 of this embodiment, the mirror 9 is positioned at a higher position than the position where the wafer 2 is set in the aligner device 4.

This allows the series of operations of photographing the wafer 2 and then setting it in the aligner device 4 to be carried out smoothly.

In this embodiment, the camera 3 captures images using a method that includes an insertion process and an image capture process. In the insertion process, the robot 1 inserts at least a portion of the hand 10 into the space below the mirror 9 that is tilted relative to the horizontal plane. In the image capture process, the camera 3 captures an image of the upper surface of the hand 10 through the mirror 9.

This allows the camera 3, which is positioned horizontally, to capture a wide range of images of the area above the hand 10. This makes it possible to easily obtain useful information about the robot 1 with a compact configuration.

The above describes a preferred embodiment of the present invention, but the above configuration can be modified, for example, as follows:

The image captured by the camera 3 through the mirror 9 can also be used for purposes other than detecting the rough orientation of the notch 2a. For example, the camera 3 can capture an image of the hand 10 without holding the wafer 2, and the image from the camera 3 can be used by the controller 5 to automatically determine the degree of wear of the edge guide portion 6. This result can be used, for example, to determine when maintenance of the hand 10 is required. The image captured by the camera 3 can also be used to determine whether the pressing member 7 is worn or not, or to determine whether there is an abnormality in the clamping operation by the pressing member 7.

The hand 10 can also be configured as a suction hand. In this case, the image captured by the camera 3 can be used to detect the amount of eccentricity of the wafer 2 with respect to the hand 10 when the wafer 2 is held by the hand 10, or to detect an abnormal state of the wafer 2 held by the hand 10 (e.g., cracks or chips in the wafer 2).

Mirror 9 can be configured as a plane mirror or as a curved mirror with a convex or concave surface.

The mirror 9 can also be placed on top of the aligner device 4 instead of to the side of the aligner device 4.

As long as there is a certain relationship between the orientation of the hand 10 when the wafer 2 is photographed by the mirror 9 (first orientation) and the orientation of the hand 10 when the wafer 2 is set in the aligner device 4 (second orientation), the first orientation and the second orientation do not have to be the same.

In the above embodiment, the controller 5 for controlling the robot 1 controls the aligner device 4. The controller 5 also analyzes the images input from the camera 3. However, at least one of the control of the aligner device 4 and the analysis of the images may be configured to be performed by a computer other than the controller 5.

The shooting angle of the camera 3 does not have to be strictly horizontal, as long as it is substantially horizontal. The camera 3 may be placed on a part other than the hand 10, for example, on the first link 15 or the second link 16.

The number of joints of the robot 1 is not limited to three, but can be one, two, or four or more. Instead of being a horizontal multi-joint type, the robot 1 can also be configured as a vertical multi-joint type or a linear motion type.

It is preferable that the camera 3 captures the image while the hand 10 is stationary, but it may also capture the image while the hand 10 is moving and passing under the mirror 9.

The aligner device 4 can be used not only to detect and adjust the orientation of the wafer 2, but also to detect positional misalignment of the wafer 2. Positional misalignment of the wafer 2 means the misalignment of the center position of the wafer 2 relative to the center of rotation of the rotating table 41.

It is apparent that the present invention is susceptible to many modifications and variations in light of the above teachings. It is therefore to be understood that within the scope of the appended claims, the invention may be practiced otherwise than as specifically described herein.

1 Robot 2 Wafer (substrate)
2a Notch (recess)
3. Camera (imaging device)
4 Aligner device 5 Controller (control device)
9 Mirror 10 Hand 41 Rotating table (rotating part)
42 Line sensor (sensor)
100 Robot System

Claims (8)

Miller and
a robot having a hand for holding a substrate;
an imaging device provided on the robot so that a photographing angle is horizontal;
Equipped with
the robot is capable of changing a position of the hand relative to the mirror;
The mirror is disposed at an angle with respect to a horizontal plane,
When the robot has inserted at least a part of the hand into a space below the mirror, the imaging device captures an image of an upper surface side of the hand through the mirror;
an aligner device for adjusting the orientation of the set substrate;
the imaging device captures an image of the substrate held on the upper surface side of the hand through the mirror;
A robot system, characterized in that the operation of the aligner device for adjusting the orientation of the substrate is changed based on an image captured by the imaging device . The robot system according to claim 1 ,
The robot system is characterized in that the robot is configured as a horizontal articulated robot. The robot system according to claim 1 or 2 ,
The substrate is a disk having a recess or a flat portion formed on an outer periphery thereof,
The aligner device comprises:
A rotating unit that rotates the substrate;
a sensor that detects the recess or the flat portion at a constant phase with respect to a rotation center of the rotating portion;
Equipped with
The aligner device is a robot system characterized in that the rotation unit changes the direction in which the substrate is rotated in order to detect the recessed portion or flat portion with the sensor, based on the position of the recessed portion or flat portion photographed by the imaging device. The robot system according to any one of claims 1 to 3 ,
A robot system, wherein the mirror is disposed at a position higher than a position at which the substrate is set in the aligner device. The robot system according to claim 1 ,
a guide portion for guiding the held substrate is disposed on an upper surface of the hand;
The robot system is characterized in that the imaging device detects an abnormality in the guide portion based on an image captured through the mirror. a robot having a hand for holding a substrate;
an imaging device provided on the robot so that a photographing angle is horizontal;
an aligner device for adjusting the orientation of the set substrate;
A method for photographing in a robot system comprising:
an insertion step in which the robot inserts at least a part of the hand into a space below a mirror that is inclined with respect to a horizontal plane;
an imaging step of the imaging device imaging an upper surface side of the hand through the mirror;
Including,
In the photographing step, the imaging device photographs the substrate held on the upper surface side of the hand through the mirror,
An imaging method , comprising changing an operation of the aligner device for adjusting an orientation of the substrate based on an image captured by the imaging device . The photographing method according to claim 6 ,
The photographing method according to the present invention, wherein the robot is configured as a horizontal articulated robot. The imaging method according to claim 6 or 7,
The imaging method according to claim 1, wherein the mirror is disposed at a position higher than a position at which the substrate is set in the aligner apparatus.

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