Wafer transfer robot and wafer unloading method

Abstract

To provide a wafer transfer robot which properly takes out and transfers a wafer even based on actual three dimensional information of the wafer.SOLUTION: A robot 10 includes an arm 13, a hand 14, a camera 15, a calculation part, and an operation control part. The hand 14 is attached to the arm 13, and supports and transfers the wafer 21. The camera 15 is attached to the hand 14 and photographs the wafer 21 disposed at the take-out position from a plurality of viewpoints to acquire an image of the wafer 21. The calculation unit calculates three dimensional information of the wafer 21 based on the hand 14 acquired by the camera 15. The operation controller moves the hand 14 to take out the wafer 21 based on the three dimensional information of the wafer 21 calculated by the calculator.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention mainly relates to a wafer transport robot that transports wafers. [Background technology]

[0002] Wafer transport robots that transport wafers for manufacturing semiconductor devices have been known for some time. Wafer transport robots are generally horizontal articulated robots that have multiple arms and hands that rotate around a vertical axis.

[0003] Patent Document 1 discloses a vertically articulated arm robot. A work tool and a camera are attached to the tip of the arm. The work tool is a robot hand or a welding tool, and performs work on an object. The camera photographs the object. Patent Document 1 discloses calculating the three-dimensional position of the object based on multiple images taken by the camera. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Laid-Open No. 2010-117223 Summary of the Invention [Problem to be solved by the invention]

[0005] The wafer transport robot operates its arms and hands based on pre-programmed information to pick up and transport a wafer placed at a pick-up position. However, if the wafer is misaligned from its predetermined position or if there is a change in the wafer shape, such as due to wafer warpage, the wafer transport robot may not be able to pick up the wafer properly. In this regard, Patent Document 1 does not disclose the horizontal articulated robot or wafer pick-up.

[0006] The present invention has been made in view of the above circumstances, and its main object is to provide a wafer transport robot that can appropriately pick up and transport a wafer based on three-dimensional information about the wafer. [Means for solving the problem]

[0007] The problem to be solved by the present invention is as described above. Next, the means for solving this problem and the effects thereof will be explained.

[0008] According to a first aspect of the present invention, there is provided a wafer transport robot having the following configuration. Specifically, the wafer transport robot is a horizontal articulated type and transports wafers. The wafer transport robot includes an arm, a hand, a camera, a calculation unit, and an operation control unit. The hand is attached to the arm and supports and transports a wafer. The camera is attached to the hand and photographs the wafer placed at a removal position from multiple viewpoints to acquire images of the wafer. The calculation unit calculates three-dimensional information of the wafer based on the images acquired by the camera. The operation control unit moves the hand to remove the wafer based on the three-dimensional information of the wafer calculated by the calculation unit.

[0009] According to a second aspect of the present invention, there is provided the following wafer removal method. Specifically, in the wafer removal method, a wafer placed at a removal position is removed using a horizontal articulated robot. The wafer removal method includes a photographing step, a calculation step, and a removal step. In the photographing step, a camera attached to a hand of the robot is used to photograph the wafer placed at the removal position from multiple viewpoints to obtain images of the wafer. In the calculation step, three-dimensional information of the wafer is calculated based on the images obtained in the photographing step. In the removal step, the hand is moved to remove the wafer based on the three-dimensional information of the wafer calculated in the calculation step.

[0010] This allows the wafer to be removed by calculating three-dimensional information about the wafer and recognizing its actual position or shape. [Effects of the Invention]

[0011] According to the present invention, the wafer can be appropriately removed and transported based on the three-dimensional information of the wafer. [Brief explanation of the drawings]

[0012] [Figure 1] FIG. 1 is a perspective view of a robot according to a first embodiment. [Figure 2] Robot block diagram. [Figure 3] 10 is a flowchart showing a process performed by the control device when performing a wafer unloading operation. [Figure 4] 10A and 10B are diagrams showing how a camera provided on a hand photographs a wafer and the photographed image. [Figure 5] FIG. 10 is a side view showing how a camera provided on the hand photographs a wafer. [Figure 6] FIG. 10 is a plan view of a robot according to a second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0013] Next, an embodiment of the present invention will be described with reference to the drawings. Fig. 1 is a perspective view showing the overall configuration of a robot (wafer transport robot) 10 according to a first embodiment. Fig. 2 is a block diagram of the robot 10.

[0014] The robot 10 is a SCARA type horizontal articulated robot. SCARA is an abbreviation for Selective Compliance Assembly Robot Arm. The robot 10 is installed in a factory that manufactures or processes wafers, and performs the task of transporting wafers 21 between multiple positions. The environment in which the robot 10 is installed is a clean environment and a vacuum environment.

[0015] The robot 10 mainly includes a base 11, an elevator shaft 12, an arm 13, a hand 14, a camera 15, and a control device 18.

[0016] The base 11 is fixed to the floor or the like of a factory. However, without being limited to this, the base 11 may be fixed to, for example, an appropriate processing facility or the ceiling surface.

[0017] The lifting shaft 12 connects the base 11 and the arm 13. The lifting shaft 12 is movable in the vertical direction relative to the base 11. By raising and lowering the lifting shaft 12, the height of the arm 13 and the hand 14 can be changed.

[0018] The arm 13 includes a first arm 13a and a second arm 13b. The first arm 13a is a thin, elongated member extending linearly in the horizontal direction. One longitudinal end of the first arm 13a is attached to the upper end of the lifting shaft 12. The first arm 13a is supported rotatably about the axis (vertical axis) of the lifting shaft 12. The second arm 13b is attached to the other longitudinal end of the first arm 13a. The second arm 13b is a thin, elongated member extending linearly in the horizontal direction. One longitudinal end of the second arm 13b is attached to the tip of the first arm 13a. The second arm 13b is supported rotatably about an axis (vertical axis) parallel to the lifting shaft 12. The hand 14 is attached to the other longitudinal end of the second arm 13b. The configuration of the arm 13 is not limited to that of this embodiment.

[0019] The hand 14 is a so-called passive grip type, and carries the wafer 21. The hand 14 includes a base portion 14a and a tip portion 14b.

[0020] The base 14a is attached to the tip of the second arm 13b. The base 14a is rotatable about an axis (vertical axis) parallel to the lift shaft 12. The tip 14b is attached to the tip of the base 14a. The tip 14b is a thin, generally U-shaped member having a branched structure. The tip 14b rotates integrally with the base 14a. The wafer 21 is placed on the tip 14b. The base 14a and the tip 14b may be integrally formed.

[0021] The hand 14 is not limited to a passive grip type. The hand 14 may be an edge grip type or a suction type. In a passive grip type, the wafer 21 placed on the hand 14 is not fixed, but in an edge grip type, the edge of the wafer 21 placed on the hand 14 is clamped and fixed. In the suction type, the wafer 21 is transported by being sucked by negative pressure (for example, a Bernoulli chuck). In either configuration, the hand supports the wafer 21 and transports it. Two hands 14 may be provided on the arm 13.

[0022] The lifting shaft 12, the first arm 13a, the second arm 13b, and the base 14a are each driven by an actuator 16 shown in the block diagram of Fig. 2. Although only one actuator 16 is shown in Fig. 2, in reality, an actuator 16 is provided for each movable part.

[0023] Encoders 17 are attached to arm joints located between the lifting shaft 12 and the first arm 13a, between the first arm 13a and the second arm 13b, and between the second arm 13b and the base 14a to detect the rotational position of each member. In addition, encoders 17 are also provided at appropriate positions on the robot 10 to detect changes in the position of the first arm 13a in the height direction (i.e., the amount of elevation of the lifting shaft 12). Although only one encoder 17 is shown in Fig. 2, an encoder 17 is actually provided for each joint.

[0024] The camera 15 is provided on the upper surface of the hand 14, specifically on the upper surface of the base 14a. The camera 15 is fixed so as to rotate integrally with the hand 14 (so as not to rotate relative to the hand 14). The optical axis of the camera 15 points toward the tip of the hand 14. The optical axis of the camera 15 indicates the direction in which the camera 15 acquires an image, and more specifically, is a straight line passing through the imaging element of the camera 15 and parallel to the axial direction of the camera 15. The camera 15 is not a stereo camera but a monocular camera. Therefore, the camera 15 creates one image by capturing an image from one viewpoint using one imaging element. The viewpoint refers to the position and orientation of the camera 15 (imaging element) when capturing an image of a certain object.

[0025] The camera 15 photographs and acquires images of a plurality of wafers 21 housed in an openable container (housing body) 20. The container 20 is, for example, a FOUP (Front Opening Unified Pod). A plurality of wafers 21 are arranged in the container 20, arranged in the thickness direction. The number of wafers 21 that can be housed is not particularly limited, but is, for example, 10 to 40, and generally, a container 20 that can house 25 wafers 21 is often used. Note that instead of the container 20, another housing body, for example, an openable shelf for storing the wafers 21, may be used. Since the robot 10 of this embodiment takes out the wafers 21 housed in the container 20, the housing position of the container 20 corresponds to the take-out position.

[0026] In this embodiment, the base 14a is located higher than the tip 14b, so the tip 14b is unlikely to appear in the image. The heights of the base 14a and the tip 14b may be the same. The camera 15 may also be provided on the base 14a. In this embodiment, the camera 15 (image pickup element) is located on an extension of a line connecting the rotation center of the base 14a and the center of the tip 14b (the center position of the wafer 21 when the wafer 21 is placed) in a plan view. However, the camera 15 may also be located at a position away from this extension.

[0027] The control device 18 includes a storage unit 18a such as an HDD, SSD, or flash memory, and an arithmetic unit such as a CPU. The arithmetic unit functions as a calculation unit 18b and an operation control unit 18c by executing a program stored in the storage unit 18a. The calculation unit 18b performs a process of calculating the three-dimensional position and three-dimensional shape of the wafer 21 based on an image acquired by the camera 15 (details will be described later). The operation control unit 18c controls the operation of the lift shaft 12, the first arm 13a, the second arm 13b, and the hand 14 based on the height of the lift shaft 12, the rotational position of the first arm 13a, the rotational position of the second arm 13b, and the rotational position of the hand 14 detected by the encoder 17.

[0028] Next, a process (wafer removal method) in which the robot 10 removes and transfers the wafers 21 accommodated in the container 20 will be described with reference to FIGS.

[0029] In this embodiment, first, a camera 15 provided on the robot 10 is used to photograph the wafer 21 contained in the container 20. Then, the three-dimensional position and three-dimensional shape of the wafer 21 are calculated based on the image of the wafer 21, and the robot 10 is operated based on these to remove the wafer 21. This will be described in detail below.

[0030] First, the control device 18 (operation control unit 18c) moves the hand 14 to the first photographing position (S101). The horizontal position of the first photographing position is a position facing the opening surface of the container 20, as shown in FIG. 4. The height of the first photographing position is a height at which the camera 15 is located below the midpoint in the height direction of the container 20 (in other words, the midpoint of the line segment connecting the uppermost wafer 21 and the lowermost wafer 21), as shown in FIG. 5. By positioning the camera 15 at a relatively low position, the hand 14 is less likely to get in the way of photographing the wafers 21, so that many wafers 21 can be photographed in one image.

[0031] Next, the control device 18 uses the camera 15 to photograph the wafers 21 to obtain a first image 101 (S102, photographing step). The first image 101 is an image photographed and obtained by the camera 15 when the hand 14 is located at the first photographing position. As shown in FIG. 5, the first image 101 includes all of the wafers 21 contained in the container 20. Note that the first image 101 may include only some of the wafers 21 contained in the container 20.

[0032] Next, the control device 18 (operation control unit 18c) moves the hand 14 to the second photographing position (S103). The horizontal position of the second photographing position is a position facing the opening surface of the container 20, as shown in FIG. 4. In this embodiment, the distance from the container 20 to the first photographing position and the distance from the container 20 to the second photographing position are the same, but may be different. The height of the second photographing position is a height at which the camera 15 is located below the midpoint of the container 20 in the height direction, as shown in FIG. 5. In this embodiment, the height of the second photographing position is the same as that in the first embodiment, but may be different.

[0033] Next, the control device 18 uses the camera 15 to photograph the wafers 21 to acquire a second image 102 (S104, photographing step). The second image 102 is an image captured by the camera 15 when the hand 14 is positioned at the second photographing position. As shown in FIG. 5, the second image 102 includes all of the wafers 21 contained in the container 20. Note that the second image 102 may include only some of the wafers 21 contained in the container 20.

[0034] Next, the control device 18 (calculation unit 18b) calculates the three-dimensional position and three-dimensional shape of the wafer 21 based on the first image and the second image (S105, calculation step). Specifically, the control device 18 calculates the misalignment (parallax) between the corresponding positions of the first image and the second image by performing a known stereo matching process on the first image and the second image. The control device 18 calculates the three-dimensional position of the target pixel (object) based on the calculated parallax, the first photographing position (specifically, the position of the camera 15), and the second photographing position (specifically, the position of the camera 15). Note that the first photographing position and the second photographing position are predetermined and stored in the storage unit 18a, and therefore are known values. In particular, the horizontally articulated robot that transports the wafer 21 is capable of precise position control, and therefore can stop at the first photographing position and the second photographing position with high accuracy.

[0035] By performing the above processing, the three-dimensional position of each pixel constituting the wafer 21 can be calculated. This makes it possible to calculate three-dimensional information about the wafer 21. The three-dimensional information is information that includes at least one of the three-dimensional position and the three-dimensional shape. The three-dimensional position of the wafer 21 is the three-dimensional position (coordinate value) of a reference point (any position, for example, the center) of the wafer 21. The three-dimensional shape of the wafer 21 is the shape that is created by matching the three-dimensional positions of the surface of the corresponding wafer 21.

[0036] In this embodiment, the first image and the second image include all of the wafers 21 contained in the container 20. Therefore, in the process of step S105, the three-dimensional positions and three-dimensional shapes of all of the wafers 21 contained in the container 20 are calculated.

[0037] Next, the control device 18 corrects the teaching information based on the three-dimensional position and three-dimensional shape of the wafer 21 (S106). The teaching information is information that defines the position and order in which the robot 10 is to operate. The control device 18 operates the lifting shaft 12, the arm 13, and the hand 14 in accordance with the teaching information, thereby sequentially removing the wafers 21 contained in the container 20 and transporting them to a predetermined position. Here, the teaching information created in advance is based on the premise that the wafer 21 is in an ideal position. The wafer 21 being in an ideal position means, for example, that the center of the support position of the container 20 and the center of the wafer 21 are aligned. Furthermore, the teaching information is based on the premise that the wafer 21 has a standard shape. However, in reality, the wafer 21 may not have a standard shape (e.g., may be warped) due to heat treatment or other reasons.

[0038] Therefore, the control device 18 corrects the teaching information based on the three-dimensional position and three-dimensional shape of each wafer 21 calculated in step S105. For example, as shown in FIG. 4, if the actual position of a certain wafer 21 is shifted by n millimeters in a first direction (to the right in FIG. 4), the teaching information is also increased by n millimeters in the first direction. Furthermore, if a certain wafer 21 is warped, the teaching information is changed so that the hand 14 does not collide with the warped portion. From another perspective, the control device 18 corrects the teaching information so that the reference position of the hand 14 (e.g., the center) and the reference position of the wafer 21 (e.g., the center and the bottom surface) coincide with each other.

[0039] In this embodiment, the previously created teaching information is corrected. Alternatively, the teaching information may be newly created based on the three-dimensional position and three-dimensional shape of the wafer 21 created in step S105 without calculating the teaching information in advance.

[0040] Thereafter, the control device (operation control unit 18c) 18 controls the elevator shaft 12, the arm 13, and the hand 14 based on the teaching information corrected in step S106 to remove and transport the wafer 21 (removal step, S107).

[0041] By performing the above processing, the wafer 21 can be appropriately removed even if the three-dimensional position or three-dimensional shape of the wafer 21 differs from the taught position. Note that it is also possible to calculate only the three-dimensional position of the wafer 21 without calculating the three-dimensional shape, and correct or create the taught information based on only the three-dimensional position. Alternatively, it is also possible to calculate only the three-dimensional shape of the wafer 21 without calculating the three-dimensional position, and correct or create the taught information based on only the three-dimensional shape.

[0042] Next, a second embodiment will be described with reference to FIG.

[0043] In the above embodiment, the hand 14 is moved to photograph the wafer 21 at the first photographing position and the second photographing position, thereby acquiring two images for calculating three-dimensional position information. With this configuration, only one camera 15 is required, and there is no need to use a stereo camera, or there is no need to use two cameras 15, so this can be achieved at low cost.

[0044] In contrast, in the second embodiment, as shown in FIG. 6, two cameras 15 are arranged on the hand 14. In this case, two images for calculating three-dimensional information can be obtained by simply photographing the wafer 21 at one photographing position. In the second embodiment, since only one photographing position is required, the time required for processing to calculate the three-dimensional information of the wafer 21 can be reduced. Note that instead of a configuration in which two cameras 15 are provided, a stereo camera (a camera configured with two image pickup elements provided in one housing) may be used.

[0045] As described above, the robot 10 of this embodiment is a horizontal articulated robot that transports the wafer 21. The robot 10 includes the arm 13, the hand 14, the camera 15, the calculation unit 18b, and the operation control unit 18c. The hand 14 is attached to the arm 13 and supports and transports the wafer 21. The camera 15 is attached to the hand 14 and photographs the wafer 21, which is placed at a removal position, from multiple viewpoints to acquire images of the wafer 21 (photographing step). The calculation unit 18b calculates three-dimensional information of the wafer 21 based on the image of the hand 14 acquired by the camera 15 (calculation step). The operation control unit 18c moves the hand 14 to remove the wafer 21 based on the three-dimensional information of the wafer 21 calculated by the calculation unit 18b (removal step).

[0046] As a result, by calculating three-dimensional information of the wafer 21, the actual position or shape of the wafer 21 can be recognized, and the wafer 21 can be taken out.

[0047] In the robot 10 of this embodiment, a plurality of wafers 21 are placed at the take-out position. The camera 15 acquires images including the plurality of wafers 21 from a plurality of viewpoints. The calculation unit 18b calculates three-dimensional information of the plurality of wafers 21 based on the images captured by the camera 15.

[0048] This allows the calculation of three-dimensional information for a plurality of wafers 21 more efficiently than the process of calculating three-dimensional information for each wafer 21 one by one.

[0049] In the robot 10 of this embodiment, wafers 21 are stored in a container 20 that can store a plurality of wafers 21. The camera 15 acquires an image that includes all of the wafers 21 stored in one container 20. The calculation unit 18b calculates three-dimensional information of all of the wafers 21 stored in the container 20 based on the image captured by the camera 15.

[0050] This allows the wafers 21 housed in the container 20 to be removed efficiently.

[0051] In the robot 10 of this embodiment, the calculation unit 18b calculates three-dimensional information of all the wafers 21 contained in one container 20 based on two images captured by the camera 15.

[0052] This allows for more efficient calculation of three-dimensional information of a plurality of wafers 21 compared to a configuration in which three or more images are acquired and the same processing is performed.

[0053] In the robot 10 of this embodiment, a camera 15 is disposed on the upper surface of the hand 14, and the camera 15 photographs the wafer 21 from a position below the center of the container 20 in the height direction.

[0054] This makes it less likely that the hand 14 will get in the way when photographing the wafer 21.

[0055] In the robot 10 of this embodiment, the operation control unit 18c moves the hand 14 so that the reference position of the wafer 21 and the reference position of the hand 14 are aligned, and then the wafer 21 is taken out.

[0056] This allows the wafer 21 to be properly removed.

[0057] In the robot 10 of this embodiment, the calculation unit 18b calculates the three-dimensional position and three-dimensional shape of the wafer 21. The operation control unit 18c moves the hand 14 to remove the wafer 21 based on the three-dimensional position and three-dimensional shape of the wafer 21 calculated by the calculation unit 18b.

[0058] This allows the wafer 21 to be properly removed even if the wafer 21 does not have a standard shape.

[0059] In the robot 10 of this embodiment, the camera 15 is a monocular camera with one imaging element. One monocular camera is disposed in the hand 14. The operation control unit 18c positions the hand 14 at a first photographing position to photograph the wafer 21, and then positions the hand 14 at a second photographing position to photograph the wafer 21, thereby acquiring images of the wafer 21 from multiple viewpoints.

[0060] This makes it possible to acquire images of the wafer 21 from multiple viewpoints without arranging two cameras 15 or using a stereo camera.

[0061] The preferred embodiment of the present invention has been described above, but the above configuration can be modified, for example, as follows.

[0062] In the above embodiment, the three-dimensional position and three-dimensional shape are calculated by acquiring an image of the wafer 21 contained in the container 20. Alternatively, the three-dimensional position and three-dimensional shape may be calculated by acquiring an image of the wafer 21 not contained in the container 20 (for example, the wafer 21 placed on a work table).

[0063] In the above embodiment, the first image 101 and the second image 102 are used to calculate the three-dimensional positions and three-dimensional shapes of all of the wafers 21 contained in the container 20. Alternatively, three or more images may be used to calculate the three-dimensional positions and three-dimensional shapes of all of the wafers 21 contained in the container 20. This makes it possible to deal with cases where it is difficult to obtain an image that includes all of the wafers 21 contained in the container 20.

[0064] The flowcharts shown in the above embodiments are merely examples, and some processes may be omitted, some processes may be changed, or new processes may be added. For example, in the above embodiments, the teaching information of all wafers 21 stored in the wafer 21 is first corrected, and then removal of the wafers 21 begins. However, the teaching information of the wafers 21 may be corrected one by one. Specifically, an image of one wafer 21 to be removed is acquired, the teaching information is corrected, and the wafer 21 is removed, and the same process is performed on the next wafer 21. [Explanation of symbols]

[0065] 10 Robot (wafer transport robot) 11 Foundation 12 Elevating axis 13 Arm 14 hands 15 Camera 20 containers 21 wafers

Claims

1. In a horizontal articulated wafer transport robot that transports wafers, Arm and a hand attached to the arm for supporting and transporting a wafer; a camera attached to the hand for photographing a wafer placed at a removal position from multiple viewpoints to acquire images of the wafer; a calculation unit that calculates three-dimensional information of the wafer based on the image acquired by the camera; an operation control unit that moves the hand to remove the wafer based on the three-dimensional information of the wafer calculated by the calculation unit; A wafer transport robot comprising:

2. 2. The wafer transport robot according to claim 1, A plurality of the wafers are disposed at the removal position, the camera acquires images including a plurality of the wafers from a plurality of viewpoints; The wafer transport robot is characterized in that the calculation unit calculates three-dimensional information of the plurality of wafers based on images captured by the camera.

3. 3. The wafer transport robot according to claim 2, The wafers are accommodated in a container capable of accommodating a plurality of the wafers, the camera acquires an image including all of the wafers contained in one of the containers; The wafer transport robot is characterized in that the calculation unit calculates three-dimensional information of all of the wafers contained in the container based on the images captured by the camera.

4. 4. The wafer transport robot according to claim 3, The wafer transport robot is characterized in that the calculation unit calculates three-dimensional information of all the wafers contained in one of the containers based on two images captured by the camera.

5. 5. The wafer transport robot according to claim 3, The wafer transport robot is characterized in that the camera is disposed on an upper surface of the hand, and the camera photographs the wafer from a position below the center of the container in the height direction.

6. 5. The wafer transport robot according to claim 1, The wafer transport robot is characterized in that the operation control unit moves the hand so as to align a reference position of the wafer with a reference position of the hand, thereby removing the wafer.

7. 7. The wafer transport robot according to claim 1, The wafer transport robot is characterized in that the operation control unit moves the hand to remove the wafer based on the three-dimensional position and three-dimensional shape of the wafer calculated by the calculation unit.

8. The wafer transport robot according to any one of claims 1 to 7, the camera is a monocular camera with one image sensor, One of the monocular cameras is disposed on the hand, The operation control unit positions the hand at a first photographing position to photograph the wafer, and then positions the hand at a second photographing position to photograph the wafer, thereby obtaining images of the wafer from multiple viewpoints.

9. A wafer removal method for removing a wafer placed at a removal position using a horizontal articulated robot, comprising: an imaging step of capturing images of the wafer placed at the removal position from multiple viewpoints using a camera attached to a hand of the robot, and acquiring images of the wafer; a calculation step of calculating three-dimensional information of the wafer based on the image acquired in the photographing step; a removal step of removing the wafer by moving the hand based on the three-dimensional information of the wafer calculated in the calculation step; A wafer removal method comprising:

Images