Conveying device and substrate processing system

Abstract

This invention provides a transport device and substrate processing system that improve transport accuracy by accurately acquiring information such as wafer diameter and wafer misalignment using pre-operation data. [Solution] In the WPS substrate processing system, before transport begins, the robot 1 performs a preliminary operation by reciprocating the hand 13 to allow the sensor 4 to detect the wafer W. During one of the reciprocating movements, the robot 1 acquires the reference position (center position) of the hand in the robot coordinate system when the sensor detects two edges of the wafer as the first and second detection position coordinates. During the other reciprocating movement, the robot 1 acquires the reference position (center position) of the hand in the robot coordinate system when the sensor detects one edge of the wafer while the hand is moved with an offset relative to the direction of travel, as the third detection position coordinate. Based on the first, second, and third detection position coordinates, the robot 1 calculates the position coordinates of the sensor in the robot coordinate system and the diameter of the wafer.

Description

[Technical Field]

[0001] The present invention relates to a transport device and a substrate processing system that have functions that contribute to improving the accuracy of correction when correcting positional misalignment of wafers during transport. [Background technology]

[0002] For example, among the robots used for wafer handling in the semiconductor field, wafer handling robots used within an EFEM (Equipment Front End Module) are equipped with aligners and other devices that detect and correct wafer misalignment.

[0003] On the other hand, for example, a wafer transport robot used in a vacuum receives the wafer in a relay chamber (called a load lock) that moves the wafer from the atmospheric environment to the vacuum environment (called a GET operation), and then transports the wafer through the vacuum chamber to the processing chamber. At this time, it is required to place the wafer in a predetermined position within the processing chamber with high precision (called a PUT operation). Furthermore, there are many spatial constraints within this type of vacuum chamber, making it difficult to equip it with wafer misalignment correction mechanisms such as aligners in addition to the robot.

[0004] Therefore, it is customary to install a sensor in the vacuum chamber or processing room, acquire the coordinate position information of the hand at the moment the sensor detects the edge of the wafer, calculate the amount of wafer displacement, and then perform the PUT operation after correcting for the displacement.

[0005] In such cases, two sensors are typically installed spaced apart in a direction perpendicular to the wafer's direction of travel. Two points (a total of four points from the two sensors) are acquired as coordinate information for detecting the wafer's edge: the moment the wafer begins to cover the top of the sensors and the moment it is released (see, for example, Patent Document 1 (Figure 1)).

[0006] Furthermore, generally, before actual operation, the wafer is placed in the correct position on the hand to obtain coordinate information regarding the sensor position, and the amount of wafer position displacement is calculated by comparing it with the sensor position coordinates during actual operation. (For example, Patent Document 2 (Figure 2)) [Prior art documents] [Patent Documents]

[0007] [Patent Document 1] Japanese Patent Publication No. 2000-12657 [Patent Document 2] Patent No. 6463227 [Overview of the project] [Problems that the invention aims to solve]

[0008] However, if there are errors in the wafer diameter or wafer position when acquiring the sensor position coordinates beforehand (during calibration), it may not be possible to obtain an accurate position, and the accuracy of subsequent wafer position correction may also deteriorate.

[0009] For example, in the above-mentioned Patent Document 2, even if the position where the center of the wafer is aligned with the center of the hand is used as the reference position when placing the wafer, and the rated diameter of the wafer is used as the basis for calculations, if the wafer is not placed in the correct reference position in the first place, or if it shifts during operation, an error will occur between the wafer coordinate system and the robot coordinate system. In addition, if there are individual differences in the diameter of the wafer, the assumptions of the calculation will be incorrect. Conventional transport devices have the potential for errors in the acquired sensor position coordinates and, consequently, in the correction of wafer position shifts due to these factors.

[0010] The present invention was made to solve the above problems, and aims to realize a transport device and a substrate processing system that improve transport accuracy by accurately acquiring information such as wafer diameter and wafer misalignment using pre-operation. [Means for solving the problem]

[0011] To achieve this objective, the present invention employs the following means.

[0012] In other words, the transport device of the present invention is A transport means for transporting a wafer held in a hand from the transport source position to the transport destination position, The system includes a sensor provided between the source position and the destination position of the transport, The transport means performs a preliminary operation before transport begins, which involves reciprocating the hand to allow the sensor to detect the edge of the wafer. During one of the reciprocating movements, the reference position of the hand in the robot coordinate system at the time when the sensor detects two edges of the wafer is acquired as the first and second detection positions. Meanwhile, during the other of the reciprocating movements, when the hand is operated with an offset relative to the direction intersecting the direction of travel, the reference position of the hand in the robot coordinate system at the time when the sensor detects one edge of the wafer is acquired as the third detection position. The method is characterized by calculating the position coordinates of the sensor in the robot coordinate system and the diameter of the wafer based on the first, second, and third detection positions.

[0013] In this way, for example, by placing the center of the wafer on the reference position of the hand and performing only one back-and-forth motion as a preliminary step, the sensor position can be measured. At the same time, the wafer diameter is also acquired, so even if there is an error in the wafer diameter when the sensor position coordinates were acquired in advance, this can be calibrated.

[0014] In this case, during the other operation of the reciprocating motion, when the hand is operated with the hand tilted at a predetermined angle around its reference position, the reference position of the hand in the robot coordinate system at the time when the sensor detects one edge of the wafer is acquired as the fourth detection position. It is preferable to use the fourth detection position to detect the misalignment of the wafer's reference position with respect to the hand's reference position.

[0015] If the angle of the hand is constant, the relative positional relationship between the hand and the wafer as seen in the robot coordinate system does not change, making it impossible to isolate the effect of wafer displacement. However, by performing edge detection with the hand tilted, the relative positional relationship between the hand and the wafer is changed, making it possible to calculate the amount of wafer displacement. Moreover, by performing this only within a single back-and-forth motion, it is possible to avoid increasing the number of man-hours.

[0016] Furthermore, it is preferable to calculate the position coordinates of the sensor in the robot coordinate system by subtracting the amount of wafer displacement from the position coordinates of the sensor.

[0017] In this way, wafer misalignment can be corrected in the robot coordinate system. Therefore, it is not necessary to place the wafer in the precise position during the preliminary operation, which reduces the amount of work required.

[0018] Preferred applications of the present invention include: A conveying device that conveys an object along a conveying track from the starting point, which is the source of the conveying, to the ending point, which is the destination of the conveying, When performing transport control using a pre-set transport track, the system includes a track correction unit that corrects the transport track so that the starting point of the transport track becomes the target starting point when the target starting point is misaligned with the starting point of the transport track. The aforementioned trajectory correction unit is characterized by correcting the trajectory by expanding or contracting the pre-correction distance along the deviation direction with respect to the endpoint, where the direction connecting the starting point before correction and the target starting point after correction is defined as the deviation direction, the distance from a certain point on the pre-correction trajectory to the endpoint is defined as the deviation direction component of the distance, and a point on the post-correction trajectory located on an axis along the deviation direction passing through the certain point is defined as the corresponding point, and the distance from the corresponding point on the post-correction trajectory to the endpoint is defined as the deviation direction component of the distance, and the trajectory is corrected by expanding or contracting the pre-correction distance along the deviation direction with respect to the endpoint, such that the ratio of the pre-correction distance to the post-correction distance is the same regardless of which of the predetermined points on the trajectory the certain point is.

[0019] In this way, the pre-correction distance and the post-correction distance can be determined for any given point on the orbit. To make the ratio the same, the pre-correction distance is expanded along the direction of the displacement with respect to the endpoint. The orbit is corrected by scaling down, so the shape of the orbit before correction is almost maintained. The trajectory is gradually corrected from the starting point to the ending point, and correction operations are performed at the start and end of transport. This method allows for correction of starting point position deviations without compromising the characteristics of the pre-correction trajectory due to rapid trajectory changes. Furthermore, because the detected position deviation is accurate, it effectively improves the overall accuracy of the trajectory correction.

[0020] In these cases, it is preferable to provide the sensors in pairs at two locations on the left and right sides of the wafer, acquire the sensor position coordinates for each, and then use the average of the wafer diameters calculated from each.

[0021] In this way, the sensor on the left can be used to calculate the wafer diameter and, consequently, the wafer's positional displacement with greater accuracy.

[0022] Regarding the above-mentioned transport device, it is preferable to configure the substrate processing system by placing it inside a vacuum chamber and transporting substrates between the vacuum chamber and a processing chamber adjacent to the vacuum chamber.

[0023] This method allows for more precise transfer of materials from the vacuum chamber to the processing chamber. [Effects of the Invention]

[0024] As described above, the present invention makes it possible to provide a transport device and a substrate processing system that improve transport accuracy by accurately acquiring information such as wafer diameter and wafer misalignment using pre-operation. [Brief explanation of the drawing]

[0025] [Figure 1] A schematic diagram of a substrate transport system according to one embodiment of the present invention. [Figure 2] A flowchart illustrating the operation of a transport device relating to one embodiment of the present invention. [Figure 3] This diagram illustrates the trajectory correction that the transport device aims to improve. [Figure 4] A schematic diagram of a transport device according to one embodiment of the present invention. [Figure 5] An explanatory diagram of the trajectory correction performed by the transport device. [Figure 6] A diagram showing the trajectory correction process during operation. [Figure 7] A diagram showing the relationship between hand movements and acquired data. [Figure 8] A diagram showing the wafer position (wafer displacement) in the hand coordinate system. [Figure 9] A flowchart showing the procedure for acquiring position coordinate data. [Figure 10] A flowchart showing the procedure for calculating the sensor position. [Figure 11] A diagram showing the definition of a coordinate system, relating to a modified version of the present invention. [Figure 12] A flowchart showing the wafer position correction procedure. [Figure 13] A diagram showing the wafer edge detection status by the sensor. [Figure 14] A diagram showing the definition of sensor position in the hand coordinate system. [Modes for carrying out the invention]

[0026] Embodiments of the present invention will be described below with reference to the drawings.

[0027] (Overall configuration of the conveying device subject to amendment in this invention) Figure 1 is a schematic diagram of the WPS substrate transport system. The WPS substrate transport system has a transport device 100 as shown in Figure 4, and this transport device 100 is configured to drive a transport robot 1, which is the transport means, by a transport control means (controller) 10. The robot 1 used in this embodiment is a horizontal articulated type and is equipped with first and second arms 11 and 12 and a hand (end effector) 13. The robot 1 used in a vacuum is placed in a vacuum chamber 2, which is a relay chamber called a load lock that moves a wafer from an atmospheric environment to a vacuum environment, and receives a wafer W from, for example, the direction perpendicular to the plane of the paper (GET operation), moves within the vacuum chamber 2, and transports the wafer W to the processing chamber 3. Transport to the processing chamber 3 involves a reciprocating motion (forward and backward motion) of the hand. In this embodiment, the motion of entering the processing chamber 3 is called the Extend operation, and the motion of moving backward from the processing chamber 3 is called the Retruct operation. At this time, it is necessary to place the wafer W in the center of the processing chamber 3 at the time of transport to the processing chamber 3 (PUT operation).

[0028] To achieve this, sensors 4 (left sensor 4L, right sensor 4R) are installed in the vacuum chamber 1 or processing chamber 3 (in this embodiment, inside the vacuum chamber 1), the timing coordinate position where the wafer W obstructs the sensors 4 is recognized, the amount of positional displacement is calculated, and a correction operation is performed by the correction amount after transport to processing chamber 3 (Extend). Regarding the calculation of the positional displacement, generally, teaching and calibration at the true position of the wafer are performed at the start of actual operation, and the wafer positional displacement is calculated by comparing it with those coordinates.

[0029] Figure 2 shows the operation flow, and Figure 3 is an explanatory diagram of trajectory correction. When calibration is started, first an Extend operation is performed (step S1), and the amount of deviation (correction amount) from the true position of the wafer W is calculated using sensor 4 (step S2). Next, the wafer W is extended again from the starting point S to the ending point (completion position) E along the pre-entered trajectory data Pt, and once it reaches the completion position (step S3), the wafer W is moved by the correction amount from the completion position E (step S4), and the movement ends at the corrected completion position E'.

[0030] However, since this wafer correction operation is performed after the wafer has been extended from the starting point S to the ending point E, a decrease in transport efficiency (throughput) becomes a problem. Furthermore, when performing the correction operation from E to E', the wafer's central acceleration is not taken into account, which may cause further positional misalignment at the time of the correction operation.

[0031] (Use of trajectory correction from prior patents) Therefore, in this embodiment, the patented invention described in Japanese Patent No. 5439665 is applied. This patented invention corrects the positional deviation of the entire trajectory for known positional deviations of the starting or stopping position that occur during teaching, without impairing the original trajectory characteristics.

[0032] This patented invention will be explained based on Figures 4 and 5. A transport device 100 that transports a wafer W along a transport track Pt from a starting point S to an ending point E, When the transport control unit 10b performs transport control using the transport track Pt which has been set in memory as trajectory data 10a in advance, the system includes a trajectory correction unit 10c which corrects the transport track Pt so that the starting point S of the transport track Pt becomes the target starting point S' when the position deviation detection device SE detects that the target starting point S' is misaligned from the starting point S of the transport track Pt.

[0033] The trajectory correction unit 10c sets the direction of the deviation G to be the direction connecting the starting point S before correction and the target starting point S' after correction, and sets the distance d1k, which is the deviation direction (G direction) component of the distance from a certain point Pk on the trajectory Pt before correction to the endpoint E(PN), as the pre-correction distance, and sets the distance d2k, which is the deviation direction (G direction) component of the distance from the corresponding point Pk' on the post-correction trajectory Pt' to the endpoint E(PN), as the corresponding point Pk', and sets the trajectory correction unit 10c to be the same regardless of which of the predetermined points Pk is on the trajectory Pt, i.e., d21 / d11=d2 k / d1 k To achieve this, the pre-correction distance d1 is set with respect to the endpoint S. kThe trajectory Pt is corrected by expanding or contracting it along the displacement direction G, and the transport control unit 10b controls the robot 1, which is the transport means, based on this correction.

[0034] When viewed in terms of the joint drive system of a multi-joint robot, as shown in equation (A), the trajectory Pt is corrected to trajectory Pt' by arranging θ'k such that the ratio (percentage β) of the angle difference θk-θ1 between the pre-correction angle θk at a certain point and the endpoint angle θ1 is kept the same as the ratio of the angle difference θ'k-θ1 between the corrected angle θ'k at that point and the endpoint angle θ1. β=d2N / d1N=(θ´k-θ1) / (θk-θ1) …(A)

[0035] This approach allows for the detection of positional misalignment and correction to the stopping position to be completed during transport. This eliminates the need for correction operations (minor movements) that would normally be performed after the Extend operation is complete, thus preventing a decrease in transport efficiency.

[0036] However, the above-mentioned patent invention deals with correcting positional misalignment caused by teaching, and does not mention correction for positional misalignment (wafer misalignment) during operation.

[0037] (Replacement of the target of correction) Therefore, here we will focus on correcting positional deviations that occur during operation. Specifically, we will detect positional deviations that occur during operation, replace the teaching error on the transport source side detected by the positional deviation detection device SE in the patented invention with the positional deviation detected during operation, and employ a method to correct this error over the entire transport trajectory. In other words, after detecting the wafer deviation correction amount during Extend operation using, for example, the method described in Patent Documents 1 and 2, we will calculate the corrected trajectory from that point (or midway through the trajectory) to the corrected stop position, and prevent a decrease in transport efficiency by moving directly along that corrected trajectory. The trajectory correction method corrects the trajectory using a correction formula (Formula A) with respect to the corrected stop position calculated from the wafer deviation amount. Figure 6 shows the state of trajectory correction during operation. The trajectory heading towards the pre-correction stop position (pre-correction trajectory) is changed to a trajectory heading towards the corrected stop position (post-correction trajectory).

[0038] By doing so, the detection of positional deviation and the correction operation to the stopping position are completed during transport, thus eliminating the time required for the correction operation (minor movement) that previously occurred after the Extend operation was completed, and thus preventing a decrease in transport efficiency.

[0039] (Improved accuracy in detecting misalignment) For detecting the amount of wafer displacement during this extension, methods described in prior art documents 1 and 2 can be used. However, as mentioned in the background technology and challenges section, this method involves acquiring coordinate information regarding the sensor position at the correct wafer position before actual operation, and calculating the amount of wafer displacement by comparing it with those coordinates.

[0040] However, when acquiring reference data, if the PUT is not placed in the correct wafer position or if there is an error in the wafer diameter, it may not be possible to obtain accurate sensor position coordinates, which could lead to a deterioration in the accuracy of subsequent wafer position correction.

[0041] Therefore, in this embodiment, the transport means performs a preliminary operation before transport begins, by reciprocating the hand 13 together with the arms 11 and 12 to allow the sensor 4 to detect the edge of the wafer W. Figure 7 is a diagram showing the relationship between the operation of the hand 13 and the acquired data, and the reference position (center position) of the hand 13 when the sensor 4 detects the edge of the wafer W is defined as the detection position. Edge detection of the wafer W by the sensor 4 is performed by detecting the timing when the wafer W blocks and opens the optical path of the sensor 4. The center position of the hand 13 as seen in the robot coordinate system is the position corresponding to the center of the wafer W when the wafer W is properly placed on the hand 13, as shown in Figure 8, and (X H , Y H ) is defined as follows.

[0042] First, as shown in Figure 7(a), the sensor 4 performs an EXTEND operation (extend operation) when the hand 13 is extended together with the arms 11 and 12 and sent into the processing chamber, causing the sensor 4 to detect the two edges of the wafer W. Next, as shown in Figure 7(b), the hand 13 is folded together with the arms 11 and 12 with the wafer W offset by ΔX3, and retracted from the processing chamber (first RETRACT operation). The offset amount ΔX3 is defined based on the X coordinate when performing the original Extend trajectory along the Y axis. Then, the diameter Dw of the wafer W and the sensor position coordinates are obtained through these EXTEND and first RETRACT operations. Furthermore, following the first RETRACT operation, as shown in Figure 7(b), the hand 13 is tilted by a predetermined angle θ4 with the hand 13 not offset, and in that state, the hand 13 is folded and retracted from the processing chamber (second RETRACT operation). The tilt θ4 of the hand 13 is defined as the angle when the hand 13 is tilted from the Y-axis around its center, with 0° defined as the longitudinal direction of the hand 13 being oriented in the Y-axis direction. As shown in Figure 8, the center position of the wafer in the hand coordinate system of the sensor 4 corresponds to the wafer displacement xw and yw. The procedure is described below.

[0043] (Coordinate data acquisition) (i) Figure 9 is a flowchart showing the procedure for acquiring position coordinate data. In both the EXTEND operation (the operation of transporting the wafer W to the processing chamber 3) performed in step S11 and the RETRACT operation (the operation of retracting the hand 13 from the processing chamber 3) performed in step S13, the sensor 4 detects the wafer edge.

[0044] (ii) Specifically, in the EXTEND operation of step S11, the wafer W is transported straight along the normal trajectory as shown in Figure 7(a), and the four hand position coordinates in the robot coordinate system at the time when sensors L and R detect the wafer edge at two locations in step S12 are acquired as the first detection position coordinates and the second detection position coordinates of the present invention. First detection position coordinates = (X HL1 ,Y HL1 ),(XHR1 , Y HR1 ) Second detection position coordinates = (X HL2 , Y HL2 ), (X HR2 , Y HR2 )

[0045] (iii) In the RETRACT operation (the first RETRACT operation) of step S13, among the operations shown in FIG. 7(b), first, in step S14, the orbit is shifted by a predetermined amount (ΔX3) in the X direction from the normal orbit to operate the hand 13, and when the sensor 4 detects the edge at the lower part of the wafer in step S15, the two hand position coordinates in the robot coordinate system are obtained as the third detection position coordinates of the present invention. Third detection position coordinates = (X HL3 , Y HL3 ), (X HR3 , Y HR3 )

[0046] (iv) Then, in the subsequent RETRACT operation (the second RETRACT operation) shown in FIG. 7(b), the offset is released in step S16, the hand is tilted at a predetermined angle (θ4) in step S17, and when the sensor 4 detects the edge at the upper part of the wafer in step S18, the two hand position coordinates in the robot coordinate system are obtained as the fourth detection position coordinates of the present invention. Fourth detection position coordinates = (X HL4 , Y HL4 \), (X HR4 , Y HR4 )

[0047] (iii) and (iv)'s first and second RETRACT operations are carried out successively.

[0048] (Sensor position, wafer diameter calculation) (v) Then, in step S19 of FIGS. 9 and 10, the sensor position is calculated. The sensor position calculation is based on the three coordinate data points of the first to third position coordinates ((X<​​​​​​​​​The coordinates (X') of a point equidistant from (the center of a circle passing through the three points) L ,Y' L ) and the distance r to that point are calculated. Assuming there is no positional displacement of wafer W, sensor 4L is (X' L ,Y' L It is thought to be located in this (X' L ,Y' L ) will be the position coordinates of the (provisional) sensor 4L. However, the positional displacement (x) of wafer W will be considered. w, y If w) (Figure 8) is present, the calculated position coordinates of sensor 4L also have a shift. Since hand 13 is operated without tilting, there is no shift in the relative positional relationship of the three points, so r = Dw / 2 is the accurate wafer radius (step S20).

[0049] (vi) For sensor 4R, the position coordinates and wafer diameter of the provisional sensor 4R are calculated in the same manner as in (v) (step S21).

[0050] (vii) Calculate the average value of the wafer diameters obtained in (v) and (vi) to obtain the wafer diameter Dw (step S22).

[0051] (viii) Coordinate data obtained by tilting the hand (X HL4 ,Y HL4 ),(X HR4 ,Y HR4 ) and (X' obtained from (v)~(vii) L ,Y' L ), (X' R ,Y' R ), and from Dw, the wafer displacement amount is calculated (step S23).

[0052] (ix) The true sensor position in the robot coordinate system is obtained by subtracting the wafer displacement from the provisional sensor position (step S24).

[0053] The specific calculation details are shown in equations (1) to (18). The position coordinates of sensor 4L and sensor 4R are (X L,Y L ),(X R ,Y R ) is expressed as.

[0054] The coordinate data obtained by the flowchart in Figure 9 and the sensor position coordinates (X L ,Y L ),(X R ,Y R The relationship between ( ) and ( ) can be expressed by equations (1) to (8).

number

[0055] Equations (1) to (3) and (5) to (7) are based on the Pythagorean theorem, while equations (4) and (8) are based on linear transformation equations for coordinates due to rotation.

[0056] Subsequently, in the calculation of the sensor position calculation flowchart in Figure 10, the temporary sensor position is set to (X' L ,Y' L ),(X' R ,Y' R ) If so the original sensor position coordinates (X L ,Y L ),(X R ,Y R ) is shifted by the wafer displacement (xw, yw). From equations (1)~(3) and (5)~(7), the provisional sensor position (X' L ,Y' L ),(X' R ,Y' R The formulas for calculating ) are derived from equations (9) to (12).

number

[0057] The wafer diameter Dw can be calculated by substituting the values ​​obtained from equations (9) and (10) into any of equations (1) to (3). Similarly, the wafer diameter Dw can be calculated from any of equations (5) to (7) and equations (11) and (12). The wafer diameter Dw can be obtained by averaging these values.

[0058] The provisional sensor position (X') obtained in this way L ,Y' L ),(X' R ,Y' R From the wafer diameter Dw and equations (4) and (8), the wafer displacements Δxw and Δyw, expressed by equations (13) and (14), can be obtained.

number

[0059] This formula is the positional displacement of wafer W x w, y Solving for w yields equations (15) and (16).

number

[0060] The positional displacement x of the wafer W obtained in this way w, y By correcting the sensor position with w, the true sensor position coordinates (X) can be obtained as shown in equations (17) and (18). L ,Y L ),(X R ,Y R ) can be obtained.

number

[0061] In the above procedure, (ii), (iii), (v)-(vii) relate to the detection of sensor position coordinates and wafer diameter. Furthermore, (iv), (viii), and (ix) relate to the detection of wafer position displacement.

[0062] (Application to trajectory correction) Then, by applying the wafer misalignment xw,yw to the misalignment amount in the misalignment direction G in FIG. 5 of the above patent document (the misalignment amount detected by the position misalignment detection device SE), an accurate value can be assigned to S´(P´1). As a result, it becomes possible to accurately correct the trajectory from the starting point S´(P´1) including errors to the normal end point E(PN) among the trajectories from the starting point S(P1) to the end point E(PN).

[0063] (Effect) As described above, the transfer device 100 of the present embodiment includes a robot 1 as a transfer means for transferring the wafer W held by the hand 13 from the transfer source position S to the transfer destination position E, and a sensor 4 provided between the transfer source position S and the transfer destination position E, and the robot 1 performs a preliminary operation of reciprocating the hand 13 before the start of transfer to detect the edge of the wafer W by the sensor 4, At the time of one operation of the reciprocating motion, the reference positions (center positions) of the hand 13 when the sensor 4 detects two places of the edge of the wafer W are the first detection position coordinates (X HL1 ,Y HL1 ),(X HR1 ,Y HR1 ), and are obtained as the second detection position coordinates (X HL2 ,Y HL2 ),(X HR2 ,Y HR2 ). On the other hand, at the time of the other operation of the reciprocating motion, the reference position (center position) of the hand 13 when the sensor 4 detects one place of the edge of the wafer W when the hand 13 is operated in a state offset in a direction crossing the traveling direction is the third detection position coordinates (X HL3 ,Y HL3 ),(X HR3 ,Y HR3 ), and are obtained, and the first, second, and third detection position coordinates (X HL1 ,Y HL1 ),(X HR1 ,Y HR1 ), (X HL2 ,Y HL2 ),(X HR2 ,Y HR2 ), (X HL3 ,YHL3 ),(X HR3 ,Y HR3 Based on this, the position coordinates of the sensor in the robot coordinate system (X' L ,Y' L ), (X' R ,Y' R This method calculates the diameter Dw of the wafer W.

[0064] In this way, for example, by placing the center of the wafer W on the center of the hand 13 and performing a single back-and-forth motion as a preliminary step, the sensor position can be measured. At the same time, the wafer diameter Dw is also acquired, so even if there is an error in the wafer diameter Dw when the sensor position coordinates were acquired beforehand, it can be calibrated. Moreover, since the robot 1 acquires the data as part of a series of movements consisting of Extend and Retruct, the time required for data acquisition does not increase.

[0065] Furthermore, during the other reciprocating motion, when the hand 13 is operated with no offset and tilted at a predetermined angle θ4 around the center point of the hand 13, the center position of the hand 13 at the time when the sensor 4 detects one edge of the wafer is defined as the fourth detection position coordinate (X HL4 ,Y HL4 ),(X HR4 ,Y HR4 ) obtained as, Fourth detection position coordinate (X HL4 ,Y HL4 ),(X HR4 ,Y HR4 This detects the misalignment of the center position of the wafer W relative to the center position of the hand 13.

[0066] If the angle θ of the hand 13 is constant, the relative positional relationship between the hand 13 and the wafer W as seen in the robot coordinate system does not change, making it impossible to isolate the effect of wafer displacement. However, by performing edge detection with the hand 13 tilted, the relative positional relationship between the hand 13 and the wafer W is changed, making it possible to calculate the amount of wafer displacement. Furthermore, since this can be done in just one round trip, it is possible to avoid increasing the number of man-hours.

[0067] Then, by subtracting the amount of wafer W's displacement from the position coordinates of sensor 13, the position coordinates of sensor 13 in the robot coordinate system are calculated.

[0068] In this way, the wafer displacement can be corrected in the robot coordinate system. Therefore, it is not necessary to place the wafer W in the precise position during the preliminary operation, and the man-hours required for this can be reduced.

[0069] The transport device 100 of this embodiment, which is equipped with such a wafer misalignment correction function, transports the wafer W along the transport track Pt from the starting point S, which is the source of transport, to the ending point E, which is the destination of transport. When performing transport control using a pre-set transport trajectory Pt, the system includes a trajectory correction unit 10c that corrects the transport trajectory Pt so that the starting point S of the transport trajectory Pt becomes the target starting point S' if the target starting point S' is misaligned from the starting point S of the transport trajectory Pt. The trajectory correction unit 10c corrects the trajectory Pt by expanding or contracting the pre-correction distance d1k along the displacement direction with respect to the endpoint S, assuming that the direction connecting the starting point S before correction and the target starting point S' after correction is the displacement direction, the distance d1k of the distance from a certain point Pk on the pre-correction trajectory Pt to the endpoint E(PN) is the displacement direction component, and the distance from a corresponding point on the post-correction trajectory Pt' located on an axis along the displacement direction passing through a certain point Pk is the corresponding point, and the distance from the corresponding point on the post-correction trajectory Pt' to the endpoint is the displacement direction component, such that the ratio β of the pre-correction distance d1k and the post-correction distance d2k is the same regardless of which of the predetermined points on the trajectory Pt the certain point Pk is.

[0070] In this way, the trajectory is corrected by expanding or contracting the pre-correction distance along the direction of deviation, with the endpoint as the reference point, so that the ratio of the pre-correction distance to the post-correction distance is the same at any of the predetermined points on the trajectory Pt. As a result, the trajectory Pt is gradually corrected from the target starting point S' to the endpoint E while maintaining almost the shape of the pre-correction trajectory, and the characteristics of the pre-correction trajectory are not impaired by abrupt trajectory changes such as correction operations at the start or end of transport, and the positional deviation of the starting point (x w, y w) can be corrected. And the detected positional shift (x w, y Since w) also becomes accurate according to this embodiment, it becomes possible to effectively improve the overall accuracy of the trajectory correction.

[0071] Sensor 4 is provided with a pair of sensors, 4L and 4R, at two locations on the left and right sides of the wafer W. Sensor position coordinates are acquired for each sensor, and the average of the wafer diameter Dw calculated from each sensor is used.

[0072] This way, the wafer diameter Dw and, consequently, the positional deviation (x) of the wafer W can be determined with greater precision. w, y It becomes possible to calculate w).

[0073] Furthermore, by placing the robot 1, which is the transport means described above, inside the vacuum chamber 2 and calibrating the substrate processing system to transport the wafer W between the vacuum chamber 2 and the processing chamber 3 adjacent to the vacuum chamber 2, it becomes possible to transport the wafer W from the vacuum chamber 2 to the processing chamber 3 with higher precision.

[0074] Although one embodiment of the present invention has been described above, the specific configuration of each part is not limited to the embodiment described above.

[0075] (modified version) For example, the wafer misalignment detection methods described in prior art documents 1 and 2 had the problem that if there were errors in the wafer diameter or wafer position when acquiring the sensor position coordinates in advance (during calibration), the accurate position could not be obtained, and the accuracy of subsequent wafer position correction also deteriorated. Therefore, in the above embodiment of the present invention, the sensor position coordinates and wafer diameter are calculated by detecting four edges by the Extend operation and detecting two edges when the Retruct operation is performed in an offset state, and the hand coordinate system and robot coordinate system are separated and the wafer misalignment is corrected by detecting two edges when the offset is released and the hand is tilted at a predetermined angle.

[0076] On the other hand, the wafer displacement calculation methods described in prior art documents 1 and 2 do not take into account the inclination of the hand 13 when detecting the wafer edge (see Figure 11(b)), which inherently leads to errors in the calculation of the wafer displacement and a deterioration in the accuracy of position correction.

[0077] In the first place, the articulated robot 1 shown in Figure 1 operates by driving its joints, and the tilt of the hand 13 is known by the control device. Therefore, by calculating the wafer position considering the position information of the hand 1 when the sensor 4 detects the wafer edge and the angle θ of the hand 1 at that time, the wafer position correction accuracy can be improved.

[0078] To calculate the wafer center position coordinates in the robot hand coordinate system, the robot coordinate system and hand coordinate system are defined as shown in Figure 11. In Figure 11(a), the sensor position in the robot coordinate system is (X L , Y L ), (X R , Y R ) is defined as follows. In Figure 11(b), the hand position and angle in the robot coordinate system are shown as the center position X of the hand 13. H , Y H This is defined based on the following. In Figure 11(c), the wafer diameter Dw remains the same in both the robot coordinate system and the hand coordinate system, but the displacement amount (xw, yw) is defined when the wafer position is displaced relative to the hand coordinate system.

[0079] Here, the operation of extending the hand 13 together with the arms 11 and 12 and sending it to the processing chamber 3 shown in Figure 1 is called the EXTEND operation, and the operation of folding the hand 13 together with the arms 11 and 12 and retracting it from the processing chamber 13 is called the RETRACT operation.

[0080] The specific steps are shown in the flowchart in Figure 12.

[0081] (x) When the wafer position correction in step S31 starts, the wafer W is transported by the EXTEND operation in step S32, and in step S33, four sets of hand position coordinates and angles in the robot coordinate system are acquired when sensors 4L and 4R detect the upper edge and lower edge of the wafer, respectively. (Figure 13(a)~(d)) (Hand position coordinates, angle) = (X HL1 ,Y HL1 ,θ HL1 ),(X HR1 ,Y HR1 ,θ HR1 ),(X HL2 ,Y HL2 ,θ HL2 ),(X HR2 ,Y HR2 ,θ HR2 )

[0082] (xi) In step S34, the wafer center position is calculated. First, from the coordinates obtained in (x), the four sensor positions in the hand coordinate system when sensors 4L and 4R detect the wafer edge are calculated. These points are considered to be points on the wafer edge in the hand coordinate system. (See Figure 14) Sensor position = (x L1 ,y L1 ),(x L2 ,y L2 ),(x R1 ,y R1 ),(x R2 ,y R2 )

[0083] (xii) Select three of the four points obtained in (xi) and calculate the coordinates of the center of the circle passing through these three points in the hand coordinate system. These coordinates are the center position of the wafer (x w, y w)

[0084] (xiii) Since there are four ways to choose three points from four, four sets of position coordinates can be obtained by calculating in the same way.

[0085] (xiv) Once step S34 is completed, step S35 is performed to take the average value of the four sets of position coordinates and calculate the wafer displacement (xw, yw).

[0086] (xv) In step S36, the wafer transport path by robot 1 is modified based on the method shown in Figure 5 to correct the wafer displacement amount (xw, yw) obtained in (xiv).

[0087] The following is an example of the above calculation, and the formulas for deriving the wafer center position (xw, yw) and wafer diameter Dw in the hand coordinate system are shown in equations (19) to (29). The wafer center position (xw, yw) in the hand coordinate system corresponds to the wafer displacement.

number

[0088] When sensor 4 detects the wafer edge, the sensor position coordinates (x) in the hand coordinate system are as follows: L1 ,y L1 ),(x L2 ,y L2 ), (x R1 ,y R1 ), (x R2 ,y R2 The coordinates are expressed by equations (19) to (26) using the sensor position coordinates, hand position coordinates, and hand angle in the robot coordinate system. The four points represented by these coordinates are points on the wafer edge in the hand coordinate system.

[0089] The center of the circle passing through three points (x1, y1), (x2, y2), and (x3, y3) on the xy-plane is (x w,y w) and the diameter Dw can be calculated using equations (27) to (29). Therefore, by selecting three sets of coordinates from the four sets obtained by equations (19) to (26) and substituting them into equations (27) to (29), the wafer position coordinates for those sets can be calculated.

[0090] Since there are four ways to select three sets from four, calculating for each combination yields four sets of wafer position coordinates. The average of these coordinates is then calculated and adopted as the wafer position coordinates in the hand coordinate system.

[0091] In this way, by using the hand position coordinates and angle when the sensor detects the wafer edge, the amount of wafer position displacement can be calculated with high accuracy even if there is meandering or angular deviation in the robot's movement, thereby improving the accuracy of correction.

[0092] Furthermore, because high-precision wafer position correction is possible even if the robot's movement is meandering or angularly misaligned, the accuracy of the wafer supply position does not deteriorate even if the robot is operated at high speed at the expense of trajectory tracking. Therefore, it is also possible to increase throughput by speeding up the robot's movement.

[0093] Furthermore, various modifications and practical applications are possible without departing from the spirit of the present invention.

[0094] For example, the wafer can be calculated and calibration accuracy improved by using the data from steps S11 to S15 of the flowchart shown in Figure 9 to perform the calculations from steps S20 to S22 of the flowchart shown in Figure 10. In this case, there is no need to tilt the hand.

[0095] Furthermore, in the above embodiment, the steps of acquiring data by offsetting the trajectory and acquiring data by tilting the hand were performed by a Retruct operation, but these may also be performed by an Extend operation.

[0096] Furthermore, it can also be used to detect abnormalities by checking whether there are any particularly outlier values ​​in the four sets of data obtained in step S34 of Figure 12. [Explanation of Symbols]

[0097] 13…Hand 1…Robot (transportation means) 2… Vacuum chamber 3… Processing room 4, 4L, 4R… Sensors 10c...Trajectory correction section 100... Conveyor device Dw…wafer diameter E...Destination position, stopping position, completion position, end point Pt... Conveyor track Pt´…Corrected trajectory S... Source position, starting position, starting point W...wafer WPS… PCB Processing System (X HL1 ,Y HL1 ),(X HR1 ,Y HR1 )...First detection position coordinates (X HL2 ,Y HL2 ),(X HR2 ,Y HR2 )...Second detection position coordinates (X HL3 ,Y HL3 ),(X HR3 ,YHR3 )...Third detection position coordinates (X HL4 ,Y HL4 ),(X HR4 ,Y HR4 )...4th detection position coordinates θ4…Predetermined angle

Claims

1. A transport means for transporting a wafer held in a hand from the transport source position to the transport destination position, The system includes a sensor provided between the source position and the destination position of the transport, The transport means performs a preliminary operation before transport begins, which involves reciprocating the hand to allow the sensor to detect the edge of the wafer. During one of the reciprocating movements, the reference position of the hand in the robot coordinate system at the time when the sensor detects two edges of the wafer is acquired as the first and second detection positions. Meanwhile, during the other of the reciprocating movements, when the hand is operated with an offset relative to the direction intersecting the direction of travel, the reference position of the hand in the robot coordinate system at the time when the sensor detects one edge of the wafer is acquired as the third detection position. A transport device characterized by calculating the position coordinates of the sensor in the robot coordinate system and the diameter of the wafer based on the first, second, and third detection positions.

2. During the other operation of the aforementioned reciprocating motion, when the hand is operated with the hand tilted at a predetermined angle around its reference position, the reference position of the hand in the robot coordinate system at the time when the sensor detects one edge of the wafer is acquired as the fourth detection position. The transport device according to claim 1, wherein the fourth detection position is used to detect a misalignment of the reference position of the wafer with respect to the reference position of the hand.

3. The transport device according to claim 2, wherein the position coordinates of the sensor in the robot coordinate system are calculated by subtracting the amount of wafer displacement from the position coordinates of the sensor.

4. A conveying device that conveys an object along a conveying track from a starting point, which is the source of conveying, to an ending point, which is the destination of conveying, When performing transport control using a pre-set transport track, the system includes a track correction unit that corrects the transport track so that the starting point of the transport track becomes the target starting point when the target starting point is misaligned with the starting point of the transport track. The trajectory correction unit is characterized by correcting the trajectory by expanding or contracting the pre-correction distance along the deviation direction with respect to the endpoint, with respect to the endpoint, such that the ratio of the pre-correction distance to the post-correction distance is the same regardless of which predetermined point on the trajectory the aforementioned point is. The trajectory correction unit defines the direction connecting the starting point before correction and the target starting point after correction as the deviation direction, defines the distance of the deviation direction component of the distance from a certain point to the endpoint on the post-correction trajectory as the deviation direction component, and defines a point on the post-correction trajectory located on an axis along the deviation direction passing through the aforementioned point as the corresponding point, and defines the distance of the deviation direction component of the distance from the corresponding point to the endpoint on the post-correction trajectory.

5. The sensors are provided in pairs at two locations on the left and right sides of the wafer to detect each sensor. The sensor position coordinates are obtained from each sensor, and the average of the wafer diameters calculated from each sensor is adopted as the wafer diameter. A conveying device according to any one of claims 1 to 4.

6. A substrate processing system characterized in that the transport device described in claim 5 is placed inside a vacuum chamber and configured to transport substrates between the vacuum chamber and a processing chamber adjacent to the vacuum chamber.

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