Substrate transport robot control device and joint motor control method

Abstract

To eliminate a positional misalignment in placing a substrate while inhibiting, e.g., speed variation of a hand.SOLUTION: A control device controls a substrate transport robot having a hand, a joint and a joint motor. The control device modifies, on the basis of positional misalignment information indicating a positional misalignment of a substrate being held by the hand, a target position for the hand when placing the substrate at a transport destination. In order to change the position where the hand places the substrate to the target position after the modification, the control device performs first speed control and second speed control. In the first speed control, the speed of the hand is made a constant speed by correction as the hand decelerates and approaches the target position before the modification. In the second speed control, the speed of the hand is decelerated with a gradient equal to the gradient of the speed of the hand immediately before the first speed control, and the hand is stopped at the target position after the modification. As the amount of change in the target position due to the modification increases, the time during which the first speed control is performed becomes longer.SELECTED DRAWING: Figure 9

Description

[Technical Field]

[0001] The present disclosure relates to controlling a substrate transfer robot. [Background technology]

[0002] 2. Description of the Related Art Conventionally, in a substrate transport system, when a positional deviation occurs in a substrate to be transported, a configuration is known in which the position of a hand used to place the substrate is changed to correct the positional deviation.

[0003] Patent Document 1 discloses a substrate transfer method in which a disk-shaped substrate is transferred to a substrate processing chamber by a transfer means. In Patent Document 1, a pair of sensors detects the passage of the outer edge of the wafer being transferred to the substrate processing chamber, thereby detecting the positional deviation of the wafer. The target position is corrected based on the acquired positional deviation, and as a result, the transfer path of the wafer is corrected. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Patent No. 6640321 Summary of the Invention [Problem to be solved by the invention]

[0005] In Patent Document 1, the wafer transfer path is corrected from the time the wafer positional deviation is acquired until the wafer reaches the correction target position. However, Patent Document 1 does not disclose how the correction is specifically performed.

[0006] The present disclosure has been made in consideration of the above circumstances, and its purpose is to eliminate positional misalignment of a substrate and accurately place it in a predetermined position in a substrate transport robot while suppressing fluctuations in hand speed, etc. [Means for solving the problem]

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

[0008] According to a first aspect of the present disclosure, there is provided a control device for a substrate transfer robot having the following configuration. Specifically, the control device for the substrate transfer robot controls a substrate transfer robot including a hand, a joint, and a joint motor. The hand is capable of holding a substrate. The axis of the joint faces up and down. The joint motor drives the joint. The control device corrects a target position of the hand when placing the substrate at a transfer destination based on positional deviation information indicating a positional deviation of the substrate held by the hand. To change the position at which the hand places the substrate to the corrected target position, the control device for the substrate transfer robot performs first speed control and second speed control. In the first speed control, the speed of the hand, which has been decelerating while approaching the target position before correction, is corrected to a constant speed. In the second speed control, the speed of the hand is decelerated at a slope equal to the slope of the hand speed immediately before the first speed control, and the hand is stopped at the corrected target position. As the amount of change in the target position due to the correction increases, the time for performing the first speed control becomes longer.

[0009] This makes it possible to suppress fluctuations in the hand speed while eliminating positional deviations and placing the substrate accurately at the destination.

[0010] According to a second aspect of the present disclosure, there is provided a control device for a substrate transfer robot having the following configuration. Specifically, the control device for the substrate transfer robot controls a substrate transfer robot including a hand, a joint, and a joint motor. The hand is capable of holding a substrate. The axis of the joint faces up and down. The joint motor drives the joint. The control device corrects a target position of the hand when placing the substrate at a destination based on positional deviation information indicating a positional deviation of the substrate held by the hand. To change the position at which the hand places the substrate to the corrected target position, the control device adds a speed correction function, which is a time function of a speed correction value, to the speed of the hand. The speed correction function consists of a first period and a second period. In the first period, the speed correction value is zero at the start of correction and increases linearly from zero over time. In the second period, the speed correction value decreases linearly over time from the value at the end of the first period, reaching zero at the end of correction. The end of correction occurs simultaneously with the time at which the speed of the hand before correction reaches zero. As the amount of change in the target position due to the correction increases, the gradient of the acceleration in the first period becomes steeper, and the gradient of the deceleration in the second period becomes steeper.

[0011] This makes it possible to prevent positional deviation and accurately position the substrate at the destination while suppressing a decrease in transport throughput. [Effects of the Invention]

[0012] According to the present disclosure, in a substrate transport robot, it is possible to eliminate positional deviation of a substrate and accurately place it in a predetermined position while suppressing fluctuations in the hand speed, etc. [Brief explanation of the drawings]

[0013] [Figure 1] FIG. 1 is a perspective view showing an overall configuration of a robot system according to an embodiment of the present disclosure. [Figure 2] FIG. 1 is a perspective view showing the configuration of a robot. [Figure 3] FIG. 2 is a block diagram showing the electrical configuration of a controller. [Figure 4]FIG. 10 is a plan view showing a state in which a first sensor of the positional deviation detection device detects the first passage of the outer edge of the wafer. [Figure 5] FIG. 10 is a plan view showing a state in which the first sensor of the positional deviation detection device detects the second passage of the outer edge of the wafer. [Figure 6] FIG. 10 is a conceptual diagram illustrating the correction of the hand position when placing a wafer. [Figure 7] 10 is a graph illustrating the velocity of the hand when the destination position of the hand is not corrected. [Figure 8] 6 is a graph showing a speed correction function when the position of the destination of the hand is corrected in the speed correction control of the first embodiment. [Figure 9] 10 is a graph conceptually illustrating hand speed correction. [Figure 10] FIG. 10 is a plan view illustrating a provisional target position that is set for convenience as a pre-correction position of the moving destination of the hand. [Figure 11] 10 is a graph showing a speed correction function in the speed correction control of the second embodiment. [Figure 12] 10 is a graph conceptually illustrating correction of the hand speed in the speed correction control of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0014] Next, the disclosed embodiments will be described with reference to the drawings. Fig. 1 is a perspective view showing the configuration of a robot system 100 according to an embodiment of the present disclosure. 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.

[0015] A robot system 100 shown in FIG. 1 is a system that causes a robot (substrate transport robot) 1 to perform work in a work space such as a clean room.

[0016] The robot system 100 includes a robot 1, a positional deviation detection device 4, and a controller (control device) 5.

[0017] The robot 1 functions as, for example, a wafer transfer robot that transports a wafer 2 stored in a storage container 6 to a substrate processing chamber 7. In this embodiment, the robot 1 is realized by a SCARA (Scara) type horizontal articulated robot. SCARA is an abbreviation for Selective Compliance Assembly Robot Arm.

[0018] The wafer 2 carried by the robot 1 is a type of substrate. The wafer 2 is formed in the shape of a circular thin plate.

[0019] As shown in FIG. 2, the robot 1 includes a hand (holding unit) 10, a manipulator 11, and joint motors 12a, 12b, and 12c.

[0020] The hand 10 is a type of end effector and is generally V-shaped or U-shaped in a plan view. The hand 10 is supported at the tip of a manipulator 11 (specifically, a second link 16 described below). The hand 10 rotates around a third axis c3 extending in the vertical direction relative to the second link 16.

[0021] The hand 10 can place a wafer 2. A reference position is set for the hand 10, and when the wafer 2 is placed at a predetermined position on the hand 10 without any positional deviation, the center 2c of the wafer 2 coincides with the reference position of the hand 10. Hereinafter, this reference position may be referred to as the center 10c of the hand 10.

[0022] The manipulator 11 mainly includes a base 13 , an elevation shaft 14 , a first link 15 , and a second link 16 .

[0023] The base 13 is fixed to the ground (for example, the floor of a clean room) and functions as a base member that supports the lift shaft 14.

[0024] The lifting shaft 14 moves up and down relative to the base 13. By this lifting and lowering, the heights of the first link 15, the second link 16, and the hand 10 can be changed.

[0025] The first link 15 is supported on the upper part of the lifting shaft 14. The first link 15 rotates about a first axis c1 that extends in the vertical direction relative to the lifting shaft 14. This allows the orientation of the first link 15 to be changed within a horizontal plane.

[0026] The second link 16 is supported at the tip of the first link 15. The second link 16 rotates about a second axis c2 extending in the vertical direction relative to the first link 15. This allows the orientation of the second link 16 to be changed within a horizontal plane.

[0027] In this way, the manipulator 11 is configured to include three joints whose axes face up and down. In the following, in order to identify each joint, they may be referred to by adding the symbols c1, c2, and c3 of their central axes.

[0028] The joint motors 12a, 12b, and 12c drive the joints c1, c2, and c3, respectively. This allows the position and posture of the hand 10 in a planar view to be changed in various ways. The joint motors 12a, 12b, and 12c are configured as servo motors, which are a type of electric motor.

[0029] The joint motor 12a that drives the joint c1 is disposed on the first link 15. The joint motor 12b that drives the joint c2 is disposed on the first link 15. The joint motor 12c that drives the joint c3 is disposed on the second link 16. However, the layout of each motor is not limited to the above.

[0030] The positional deviation detection device 4 includes a first sensor 41 and a second sensor 42. The first sensor 41 and the second sensor 42 are each disposed near the path along which the robot 1 transfers the wafer 2 to the substrate processing chamber 7. Just before the hand 10 reaches the substrate processing chamber 7, which is its destination, the hand 10 and the wafer 2 generally move in the direction D1 shown in FIG. 1 . The positional deviation detection device 4 is disposed near the substrate processing chamber 7, on the opposite side of the substrate processing chamber 7 from the direction D1. The first sensor 41 and the second sensor 42 can detect the passage of the outer edge of the wafer 2 while the wafer 2 is being transferred to the substrate processing chamber 7.

[0031] The first sensor 41 and the second sensor 42 are both configured as non-contact sensors. The sensor configuration is arbitrary, but they can be configured as reflective sensors, for example. Instead of reflective sensors, for example, transmission sensors may be used.

[0032] The configuration of the positional deviation detection device 4 is disclosed in Patent Document 1 and the like, so it will be briefly described below. The first sensor 41 and the second sensor 42 are disposed at an appropriate distance from each other in a plan view so as to form a gap smaller than the diameter of the wafer 2. The first sensor 41 and the second sensor 42 are both disposed with their detection axes facing in the vertical direction.

[0033] Each of the first sensor 41 and the second sensor 42 can detect the passage of the outer edge of the wafer 2. The detection results of the first sensor 41 and the second sensor 42 are input to the controller 5. The controller 5 can acquire the center position of the hand 10 at the timing when the first sensor 41 and the second sensor 42 detect the passage of the outer edge of the wafer 2, for example, by encoders (not shown) provided on the joint motors 12a, 12b, and 12c.

[0034] While the wafer 2 is being transported along the path, the first sensor 41 can detect the passage of the outer edge of the wafer 2 twice. The first detection is shown in Figure 4, and the second detection is shown in Figure 5. At the timing of each of the two passes, the controller 5 calculates the center position of the hand 10.

[0035] Here, we define a two-dimensional plane corresponding to a plan view of the transfer path of the wafer 2. Positions on the two-dimensional plane can be represented by a two-dimensional Cartesian coordinate system, as shown in FIGS. 4 and 5. On this two-dimensional plane, we consider imaginary circles with diameters equal to the diameter of the wafer 2, each centered at the center 10c of the two hands 10 obtained above. The diameter of the wafer 2 is known. Symbol C1 in FIG. 4 is an imaginary circle based on the first detection, and symbol C2 in FIG. 5 is an imaginary circle based on the second detection. In FIG. 5, imaginary circle C1 based on the first detection is drawn together with imaginary circle C2 based on the second detection.

[0036] As shown in FIG. 5, there are two intersections between the two imaginary circles C1 and C2, but of the two intersections, the intersection closest to the first sensor 41 will be focused on. The position of this intersection can be easily determined by known geometric calculations. The position of the first sensor 41 is known. The controller 5 acquires a plane vector that represents the deviation between the intersection of interest and the position of the first sensor 41. This plane vector is indicated by a white arrow in FIG. 5. This deviation can be considered to be equal to the positional deviation between the center 10c of the hand 10 and the center 2c of the wafer 2.

[0037] Detection of the positional deviation of the wafer 2 by the second sensor 42 is substantially the same as that by the first sensor 41, and will therefore be briefly described without showing it in the drawings. Like the first sensor 41, the second sensor 42 can detect the passage of the outer edge of the wafer 2 twice. At the timing of each of the two passages, the controller 5 calculates the position of the center 10c of the hand 10.

[0038] In the two-dimensional plane described above, consider imaginary circles with a diameter equal to the diameter of the wafer 2, each centered at the center 10c of the two hands 10 obtained above. There are two intersections between the two imaginary circles, and of the two intersections, focus is placed on the intersection closer to the second sensor 42. The position of the second sensor 42 is known. The controller 5 acquires a plane vector representing the deviation between the intersection of interest and the position of the second sensor 42. This deviation can be considered to be equal to the positional deviation between the center of the hand 10 and the center of the wafer 2.

[0039] The controller 5 calculates the average value of the two obtained plane vectors. This average value of the vectors corresponds to the plane vector (ox, oy) described below. By calculating the average, the positional deviation of the wafer 2 with respect to the hand 10 can be calculated with high accuracy.

[0040] It is also possible to omit one of the first sensor 41 and the second sensor 42. Instead of the first sensor 41 and the second sensor 42, a camera capable of photographing the wafer 2 being transported by the robot 1 from above may be provided, and the misalignment between the hand 10 and the wafer 2 may be obtained by performing image recognition processing on the image data captured by the camera.

[0041] As shown in Fig. 3, the controller 5 includes a deviation amount acquisition unit 51 and a control unit 52. The controller 5 is configured as a known computer including a CPU, ROM, RAM, 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 control method for the joint motors 12a, 12b, and 12c of the present disclosure. Cooperation of these hardware and software allows the controller 5 to operate as the deviation amount acquisition unit 51, the control unit 52, etc.

[0042] As described above, the misalignment amount acquisition unit 51 acquires the amount of misalignment of the wafer 2 based on the detection results of the first sensor 41 and the second sensor 42 that constitute the positional misalignment detection device 4. The amount of misalignment can be expressed, for example, by a plane vector (ox, oy).

[0043] The control unit 52 outputs command values ​​to the drive motors that drive the various parts of the robot 1, in accordance with a predetermined operation program or movement commands input by the user, to control the motors and move the hand 10 to a predetermined command position. The drive motors include an electric motor (not shown) for vertically displacing the lift shaft 14, as well as the joint motors 12a, 12b, and 12c described above.

[0044] The control unit 52 includes a destination position correction unit 53 and a speed correction unit 54.

[0045] The original position of the hand 10 when placing the wafer 2 is a position where its center 10c coincides with the reference position 7p of the substrate processing chamber 7. However, if the position of the wafer 2 relative to the hand 10 is misaligned for some reason, that misalignment will directly result in the position of the wafer 2 being misaligned with the reference position 7p of the substrate processing chamber 7. Therefore, the destination position correction unit 53 corrects the position where the hand 10 places the wafer 2 based on the misalignment amount input from the misalignment amount acquisition unit 51. The misalignment amount is information (position misalignment information) that indicates the position misalignment of the wafer 2.

[0046] The correction is performed to cancel the above-mentioned positional deviation. Specifically, the correction can be realized by inverting the plane vector (ox, oy) indicating the obtained deviation amount of the wafer 2 and adding the inverted plane vector (-ox, -oy) to the coordinates of the transfer destination of the hand 10.

[0047] Hereinafter, the plane vector after inversion may be referred to as the position correction vector. In Figure 6, the position correction vector (Δx1, Δy1) is indicated by an outline arrow. Δx1=-ox, and Δy1=-oy.

[0048] Hereinafter, the destination position of the hand 10 before correction may be referred to as the “pre-correction position,” and the destination position after correction may be referred to as the “post-correction position.” In Fig. 6, the coordinates of the pre-correction position are represented by (x1, y1), and the coordinates of the post-correction position are represented by (x1 + Δx1, y1 + Δy1).

[0049] 6, the coordinates (x1, y1) of the position before correction are the same as the coordinates of the reference position 7p of the substrate processing chamber 7 that was previously taught. However, this is for the sake of convenience to make the explanation of position correction easier to understand, and in this embodiment, the position before correction is set to a different position, which will be described later.

[0050] The control unit 52 moves the hand 10 to the corrected position, and when the movement is complete, the hand 10 places the wafer 2 in the substrate processing chamber 7. This allows the wafer 2 to be set in the substrate processing chamber 7 with the center 2c of the wafer 2 aligned with the reference position 7p of the substrate processing chamber 7.

[0051] Next, the speed control of the hand 10 performed by the speed correcting unit 54 when the positional deviation detecting device 4 detects a positional deviation will be described.

[0052] As described above, the positional deviation of the wafer 2 relative to the hand 10 is detected while the wafer 2 is being transported to the destination substrate processing chamber 7. The destination position correction unit 53 changes the destination position of the hand 10 from the pre-correction position to the corrected position while the hand 10 is transporting the wafer 2. This makes it possible to set the wafer 2 in the substrate processing chamber 7 at an accurate position while preventing a decrease in transport efficiency.

[0053] Now, consider the moment when the above-mentioned position correction vector is obtained and the destination of the hand 10 is corrected. The position correction vector is obtained at approximately the same time when the first sensor 41 and the second sensor 42 detect the passage of the outer edge of the wafer 2 a total of four times. In the example shown in FIGS. 4 and 5, the second sensor 42 completes the two detections of the outer edge of the wafer 2 between the timings shown in FIGS. 4 and 5. Therefore, the position correction vector is essentially obtained at the time shown in FIG. 5 when the first sensor 41 detects the passage of the outer edge of the wafer 2 for the second time.

[0054] The position of the center of the hand 10 at the time of Figure 5 is indicated by the symbol P0 in Figure 6. Before the destination of the hand 10 was corrected, it was supposed to move a distance (mx, my) from the position P0 at the time of Figure 5 to the reference position 7p of the destination, but after the correction, it will be necessary to move a distance (mx + Δx1, my + Δy1) from the current position P0 to the corrected position, where mx > 0, my > 0, Δx1 > 0, and Δy1 > 0.

[0055] Consider a case where, before the movement destination of the hand 10 is corrected, the speed of the hand 10 is to be controlled as shown in the graph of Fig. 7. The graph of Fig. 7 shows the transition of the speed of the hand 10 in the traveling direction.

[0056] Fig. 7 shows a situation in which the hand 10 is approaching the reference position 7p. Time t1 shown in Fig. 7 corresponds to the timing when the center of the hand 10 is at the position indicated by symbol P0 in Fig. 6. As shown in the graph in Fig. 7, the speed of the center of the hand 10 is controlled to decrease linearly continuously from before time t1.

[0057] If the movement destination is not corrected at time t1, the velocity of the center of the hand 10 continues to decrease and reaches zero at time t2. The center of the hand 10 at time t2 coincides with the reference position 7p, which is the movement destination before correction.

[0058] As will be described in detail later, the vertical axis in FIG. 7 represents the magnitude of the velocity vector. The value obtained by integrating the magnitude of this velocity vector from time t1 to time t2 is the distance from position P0 to reference position 7p, that is, √(mx 2 +my 2 )

[0059] Next, consider a case where the destination position is corrected at time t1. In response to the position correction, the speed correction unit 54 adds the time function of the speed of the center of the hand 10 before correction, shown in Fig. 7, to the time function of the speed of the center of the hand 10 before correction, shown in Fig. 8.

[0060] The time function of the velocity of the center of the hand 10 is actually a vector function. The vertical axis of the graph in Fig. 7 represents the magnitude of the vector. The direction of this velocity vector is constant and coincides with the arrow pointing from position P0 to reference position 7p in Fig. 6, and only the magnitude changes as shown in Fig. 7.

[0061] Similarly, the time function of the speed correction value is actually a vector function. The vertical axis of the graph in Figure 8 indicates the magnitude of the vector. The direction of this speed correction vector is constant and coincides with the position correction vector indicated by the white arrow in Figure 6; only the magnitude changes as shown in Figure 8.

[0062] As shown in FIG. 8, the magnitude of the velocity correction vector changes in a trapezoidal shape over time.

[0063] Specifically, between time t1 and time t2, the magnitude of the velocity correction vector increases linearly from zero to a velocity v1. Velocity v1 is the magnitude of the velocity of the center of the hand 10 at time t1. The slope at which the magnitude of the velocity correction vector increases between time t1 and time t2 is equal to the absolute value of the slope at which the magnitude of the velocity vector before correction decreases, as shown in FIG. 7.

[0064] Between time t2 and time t3, the magnitude of the velocity correction vector remains at v1.

[0065] Between time t3 and time t4, the magnitude of the velocity correction vector decreases linearly from v1 to zero. The slope of the decrease in the magnitude of the velocity correction vector between time t3 and time t4 is equal to the slope of the decrease in the magnitude of the velocity vector before correction, as shown in Figure 7.

[0066] The value obtained by integrating the magnitude of the velocity correction vector shown in FIG. 8 from time t1 to time t4 is equal to the magnitude of the position correction vector. Specifically, the magnitude of the position correction vector is expressed as follows: 2 +Δy1 28 so that the integrated value is equal to the magnitude of the position correction vector. The larger the magnitude of the position correction vector, the longer the time from time t3 to time t4.

[0067] FIG. 9 is a graph conceptually explaining the correction of the speed of the hand 10. In FIG.

[0068] The vertical axis of the graph in Figure 9 represents the sum of the magnitude of the vector shown in Figure 7 and the magnitude of the vector shown in Figure 8. Between time t1 and time t2, the magnitude of the vector shown in Figure 7 decreases linearly from v1 to zero, while the magnitude of the vector shown in Figure 8 increases linearly from zero to v1. Therefore, between time t1 and time t2, the sum of the magnitudes of the two vectors remains constant at v1.

[0069] The speed correction unit 54 corrects the speed of the hand 10 by adding the vector function for speed correction described in Fig. 8 to the speed vector function described in Fig. 7. The vector obtained by combining the two vectors indicates the speed of the center of the hand 10 after correction.

[0070] As mentioned above, the velocity vector described in FIG. 7 and the vector for velocity correction described in FIG. 8 have different directions. Therefore, the sum of the magnitudes of the two vectors does not match the magnitude of the resultant vector. However, because mx>0, my>0, Δx1>0, and Δy1>0, the directions of the two vectors are not very different. In other words, the magnitude of the resultant vector of the two vectors is similar to the sum of the magnitudes of the individual vectors.

[0071] Therefore, as shown for convenience in the graph of FIG. 9, the velocity of the center of the hand 10 after correction is roughly constant at a velocity near velocity v1 between time t1 and time t2. The velocity of the center of the hand 10 after correction is also constant at velocity v1 between time t2 and time t3. Between time t3 and time t4, the velocity of the center of the hand 10 after correction decreases toward zero at the same slope as before correction. The velocity of the hand 10 reaches zero at time t4.

[0072] This control makes it possible to correct the destination of the hand 10 while preventing excessive acceleration from occurring in the hand 10.

[0073] In the above control, the speed correction in the X-axis direction and the speed correction in the Y-axis direction are performed in conjunction with each other according to the function of FIG. 8. However, the speed correction in the X-axis direction based on the position correction amount Δx1 in the X-axis direction and the speed correction in the Y-axis direction based on the position correction amount Δy1 in the Y-axis direction may be performed separately. Typically, the position correction amount Δx1 in the X-axis direction and the position correction amount Δy1 in the Y-axis direction are different from each other. When the speed correction is performed separately for the X-axis and the Y-axis, the length of time for which the speed is corrected to be constant in the X-axis direction and the length of time for which the speed is corrected to be constant in the Y-axis direction are different from each other. Therefore, the timing at which the speed correction by the speed correction unit 54 is completed differs between the X-axis component and the Y-axis component.

[0074] Next, the setting of the destination of the hand 10 before correction will be described in detail.

[0075] Regarding the correction of the destination of the hand 10, the explanation using Figure 6 assumes that the destination (x1, y1) of the hand 10 before correction is set to coincide with the reference position 7p of the substrate processing chamber 7 that has been previously instructed.

[0076] However, positional deviation of the wafer 2 relative to the hand 10 can occur in various directions and magnitudes. Therefore, for the vector (mx+Δx1, my+Δy1) indicating the movement after the position is corrected, the difference Δx1 is not necessarily positive, and the difference Δy1 is not necessarily positive. The speed correction described in Figure 9 is based on the assumptions that mx>0, my>0, Δx1>0, and Δy1>0, and therefore cannot be performed when the difference Δx1 is negative, and cannot be performed when the difference Δy1 is negative.

[0077] To solve this problem, in this embodiment, the position before correction is set to a predetermined provisional target position P1 shown in Fig. 10, which is different from the reference position 7p of the substrate processing chamber 7 that has been taught in advance. When a range in which positional deviation of the wafer 2 can be corrected is drawn with the reference position 7p at the center, the provisional target position P1 is set to be located on the opposite side of the range from the direction D1 in which the hand 10 moves to transport the wafer 2 from the storage container 6 to the reference position 7p of the substrate processing chamber 7. Fig. 10 shows an example of the positional deviation correctable range A1 and the provisional target position P1.

[0078] The direction D1 in which the hand 10 transports the wafer 2 is positive in both the X-axis and Y-axis directions. Meanwhile, the X-coordinate of the provisional target position P1 is on the negative side of the minimum X-coordinate value within the positional deviation correctable range A1, and the Y-coordinate of the provisional target position P1 is on the negative side of the minimum Y-coordinate value within the positional deviation correctable range A1. By setting the destination position of the hand 10 before correction to the provisional target position P1, the two differences Δx1 and Δy1 can be prevented from becoming negative, regardless of the direction and magnitude of the positional deviation of the wafer 2 relative to the hand 10 within the positional deviation correctable range A1. Therefore, the speed correction described in FIG. 9 can be reliably applied.

[0079] The provisional target position P1 can be appropriately determined so as to satisfy the above conditions, provided that the first sensor 41 and the second sensor 42 are able to detect the passage of the outer edge of the wafer 2 a total of four times before the center 10c of the hand 10 reaches the provisional target position P1.

[0080] As described above, the controller 5 of the substrate transfer robot of this embodiment controls the robot 1, which includes the hand 10, joints c1, c2, and c3, and joint motors 12a, 12b, and 12c. The hand 10 can hold a wafer 2. The joints c1, c2, and c3 are arranged so that their axes face up and down. The joint motors 12a, 12b, and 12c drive the joints c1, c2, and c3. The controller 5 corrects the target position of the hand 10 when placing the wafer 2 at the transfer destination, based on positional deviation information indicating the positional deviation of the wafer 2 held by the hand 10. To change the position where the hand 10 places the wafer 2 to the corrected target position, the controller 5 performs first speed control and second speed control. In the first speed control performed from time t1 to time t3, the speed of the hand 10, which has been decelerating while approaching the target position before correction, is corrected to a constant speed. In the second speed control performed from time t3 to time t4, the speed of the hand 10 is decelerated at a gradient equal to the gradient of the speed of the hand 10 immediately before the first speed control, and the hand 10 is stopped at the corrected target position. As the amount of change in the target position due to the correction (i.e., the magnitude of the position correction vector) increases, the time during which the first speed control is performed becomes longer.

[0081] This makes it possible to eliminate positional deviations and place the wafer 2 at an accurate position in the substrate processing chamber 7 while suppressing fluctuations in the speed of the hand 10.

[0082] In the controller 5 of the robot 1 of this embodiment, the target position before correction is a provisional target position P1 that is different from a previously taught reference position 7p of the substrate processing chamber 7. The provisional target position P1 is determined to be located on the opposite side of the direction D1 in which the hand 10 moves to transport the wafer 2 from another position to the reference position 7p, within a position correctable range centered on the reference position 7p.

[0083] As a result, even if the wafer 2 is misaligned in any direction relative to the hand 10, the speed fluctuation of the hand 10 can be suppressed while the misalignment is eliminated, and the wafer 2 can be placed at an accurate position in the substrate processing chamber 7.

[0084] Next, a second embodiment will be described. In the description of this embodiment, the same or similar components as those in the previous embodiment are denoted by the same reference numerals in the drawings, and the description thereof may be omitted.

[0085] In this embodiment, the method of correction performed by the speed correction unit 54 differs from that in the first embodiment. In this embodiment, the speed correction unit 54 adds a speed correction function, which is a time function of the speed correction value, to the speed of the hand 10 before correction shown in the graph in Fig. 7. The speed correction function is shown in Fig. 11. As a result, the speed of the hand 10 is controlled as shown by the solid line in Fig. 12.

[0086] The velocity correction function resembles a triangular pulse, as shown in Figure 11. The pulse begins at time t1 and ends at time t2.

[0087] This speed correction function consists of a first period in which the speed correction value increases and a second period in which the speed correction value decreases. The first period switches to the second period at time t5. The lengths of the first and second periods are equal.

[0088] In the first period, the speed correction value is zero at time t1 and increases linearly from zero as time passes. At time t5, the speed correction value is Δv t becomes.

[0089] In the second period, the speed correction value is the value Δv t and decreases linearly with time. At time t2, the speed correction value becomes zero.

[0090] The speed of the hand 10 can be corrected by adding this speed correction function to the speed before correction.

[0091] The speed correction function shown in Fig. 11 is a vector function, similar to the speed correction function described in Fig. 8 in the first embodiment. As in the first embodiment, the speed vector described in Fig. 7 and the vector for speed correction described in Fig. 11 have different directions.

[0092] In this embodiment, even if the amount of position correction (i.e., the magnitude of the position correction vector) changes, the pulse width (length of time) of the triangular wave pulse of the speed correction function does not change. Instead, the height of the triangular wave pulse of the speed correction function, in other words, the speed correction value Δv at time t5 t changes according to the position correction amount Δx1.

[0093] Unlike the control of the first embodiment, the control of this embodiment does not change the transport time regardless of the amount of position correction, so it is possible to suppress a decrease in transport throughput and prevent variations in throughput.

[0094] In this embodiment, the provisional target position P1 described with reference to Fig. 10 is not used as the destination of the hand 10 before correction. The reference position 7p taught in advance is used as the destination of the hand 10 before correction.

[0095] As described above, the controller 5 of the robot 1 of this embodiment adds a speed correction function, which is a time function of the speed correction value, to the speed of the hand 10 in order to change the position where the hand 10 places the wafer 2 to the corrected target position. The speed correction function consists of a first period and a second period. The first period is the period from time t1 to time t5. The second period is the period from time t5 to time t2. In the first period, the speed correction value is zero at the start of correction (time t1) and increases linearly from zero as time passes. In the second period, the value Δv at the end of the first period is tThe speed correction value decreases linearly over time, reaching zero at the end of the correction. The end of the correction occurs at the same time as the speed of the hand 10 before the correction reaches zero (time t2). As the magnitude of the position correction vector increases, the slope of the acceleration in the first period becomes steeper, and the slope of the deceleration in the second period becomes steeper.

[0096] This makes it possible to prevent the wafer 2 from being displaced and transport it to an accurate position while suppressing a decrease in transport throughput.

[0097] In the controller 5 of the robot 1 of this embodiment, the target position before correction is a taught position that has been taught in advance, that is, the reference position 7p.

[0098] This allows the position where the wafer 2 is placed to be corrected from the taught position.

[0099] Although the preferred embodiment of the present disclosure has been described above, the above configuration can be modified, for example, as follows. A single modification may be made, or multiple modifications may be made in any combination.

[0100] When the speed correction of the first embodiment is performed, the destination before correction can be set to the reference position 7p, which is the original destination, instead of setting it to the provisional target position P1. If the difference Δx1 or the difference Δy1 is negative, speed correction can be performed appropriately using a method other than the above.

[0101] For example, the speed correction of the first embodiment and the speed correction of the second embodiment may be selectable by user settings.

[0102] The destination of the wafer 2 transferred by the robot 1 is not limited to the substrate processing chamber 7, but may be another location such as a load lock chamber.

[0103] The number of joints of the manipulator 11, whose axes are oriented in the up and down directions, is not limited to three, but may be one, two, four or more.

[0104] The directions of the X-axis and Y-axis in the coordinate system are arbitrary. For example, the X-axis may be defined so that the left side in Fig. 10 is the positive direction, and the Y-axis may be defined so that the bottom side is the positive direction.

[0105] The control described in the above embodiment can also be applied to the case where the robot 1 transports a substrate other than the wafer 2.

[0106] The functions of each element, including the controller 5, disclosed in this disclosure can be performed using circuits or processing circuits, including general-purpose processors, special-purpose processors, integrated circuits, ASICs (Application Specific Integrated Circuits), conventional circuits, and / or combinations thereof, configured or programmed to perform the disclosed functions. A processor is considered a processing circuit or circuit because it includes transistors and other circuitry. In this disclosure, a circuit, unit, or means is hardware that performs the recited functions or hardware that is programmed to perform the recited functions. The hardware may be hardware disclosed herein or other known hardware that is programmed or configured to perform the recited functions. Where the hardware is a processor, which is considered a type of circuit, the circuit, means, or unit is a combination of hardware and software, and the software is used to configure the hardware and / or processor. [Explanation of symbols]

[0107] 1. Robot (substrate transport robot) 2. Wafer (substrate) 5 Controller 10 hands 12a, 12b, 12c Joint motors D1 direction P1 Temporary target position c1, c2, c3 joints

Claims

1. a hand capable of holding a substrate; A joint whose axis faces up and down, a joint motor that drives the joint; A control device for controlling a substrate transport robot comprising: correcting a target position of the hand when placing the substrate at a transfer destination based on positional deviation information indicating a positional deviation of the substrate held by the hand; In order to change the position where the hand places the substrate to the corrected target position, a first speed control for correcting the speed of the hand, which has been approaching the target position before correction while decelerating, to a constant speed; a second speed control that slows down the speed of the hand at a gradient equal to the gradient of the speed of the hand immediately before the first speed control and stops the hand at the corrected target position; and 10. A control device for a substrate transport robot, wherein the time during which the first speed control is performed becomes longer as the amount of change in the target position due to the correction becomes larger.

2. a hand capable of holding a substrate; A joint whose axis faces up and down, a joint motor that drives the joint; A control device for controlling a substrate transport robot comprising: correcting a target position of the hand when placing the substrate at a transfer destination based on positional deviation information indicating a positional deviation of the substrate held by the hand; adding a speed correction function, which is a time function of a speed correction value, to the speed of the hand in order to change the position where the hand places the substrate to a corrected target position; The speed correction function is a first period in which the speed correction value is zero at the start of correction and increases linearly from zero as time passes; a second period in which the speed correction value linearly decreases over time from the value at the end of the first period to zero at the end of the correction; It consists of The correction end point is the same as the point at which the hand speed before correction reaches zero, A control device for a substrate transport robot, characterized in that as the amount of change in the target position due to the correction increases, the gradient of the acceleration in the first period becomes steeper and the gradient of the deceleration in the second period becomes steeper.

3. 2. The control device for a substrate transport robot according to claim 1, The target position before correction is a provisional target position different from a previously taught position, A control device for a substrate transport robot, characterized in that the temporary target position is determined to be located on the opposite side of the direction in which the hand moves to transport the substrate from another position to the taught position, relative to the taught position.

4. 3. The control device for a substrate transport robot according to claim 2, 10. A control device for a substrate transport robot, wherein the target position before correction is a taught position that has been taught in advance.

5. a hand capable of holding a substrate; A joint whose axis faces up and down, a joint motor that drives the joint; A method for controlling a joint motor in a substrate transport robot comprising: correcting a target position of the hand when placing the substrate at a transfer destination based on positional deviation information indicating a positional deviation of the substrate held by the hand; In order to change the position where the hand places the substrate to the corrected target position, a first speed control for correcting the speed of the hand, which has been approaching the target position before correction while decelerating, to a constant speed; a second speed control that slows down the speed of the hand at a gradient equal to the gradient of the speed of the hand immediately before the first speed control and stops the hand at the corrected target position; and a control method for a joint motor, wherein the time period during which the first speed control is performed becomes longer as the amount of change in the target position due to the correction becomes larger.

6. a hand capable of holding a substrate; A joint whose axis faces up and down, a joint motor that drives the joint; A method for controlling a joint motor in a substrate transport robot comprising: correcting a target position of the hand when placing the substrate at a transfer destination based on positional deviation information indicating a positional deviation of the substrate held by the hand; adding a speed correction function, which is a time function of a speed correction value, to the speed of the hand in order to change the position where the hand places the substrate to a corrected target position; The speed correction function is a first period in which the speed correction value is zero at the start of correction and increases linearly from zero as time passes; a second period in which the speed correction value linearly decreases over time from the value at the end of the first period to zero at the end of the correction; It consists of The correction end point is the same as the point at which the hand speed before correction reaches zero, A control device for a substrate transport robot, characterized in that as the amount of change in the target position due to the correction increases, the gradient of the acceleration in the first period becomes steeper and the gradient of the deceleration in the second period becomes steeper.

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