Workpiece conveying device and mapping method

Abstract

The present application provides a workpiece conveying device and a mapping method, which can correctly determine the inventory state of a workpiece while using a reflective sensor when performing mapping to determine the inventory state of a workpiece in a storage unit provided with a plurality of slots arranged along a first direction. One wafer as a workpiece is stored in each slot of a cassette placement table as a storage unit (step 101), and a reflective sensor is moved together with a hand to the position of the cassette placement table in this state (step 102). The sensor is moved along a second direction (horizontal direction) orthogonal to the first direction, and the operation of moving the sensor along the first direction (vertical direction) and detecting reflected light from the wafer is repeatedly performed to obtain detection distribution data (step 105). According to the detection distribution data, a mapping position used during actual work is determined (step 106).

Description

Technical Field

[0001] This invention relates to the conveying of workpieces using conveying devices such as conveying robots, and in particular to a conveying device and mapping method that improves the mapping accuracy of the inventory status of workpieces in storage units such as discrimination boxes or box-mounted platforms. Background Technology

[0002] When conveying plate-shaped workpieces such as semiconductor wafers or glass substrates using a conveying device such as a conveying robot, the workpiece is stored in a storage section, such as a box or box mounting stage. The conveying device extends its hand, located at its front end, into the storage section of the conveying source to retrieve the workpiece. The workpiece is then conveyed while resting on the hand and stored in the storage section at the conveying destination. Patent Document 1 discloses an example of a conveying robot for conveying workpieces such as semiconductor wafers. Generally, since the storage section can hold multiple workpieces, it is necessary to investigate the inventory status of workpieces in the storage section before actual conveying; this is called mapping. Multiple slots in the storage section are arranged in a vertically overlapping manner. By performing mapping, it is possible to determine which slot contains the workpiece and how many slots contain it, allowing for the assembly of an optimal conveying sequence. In the conveying sequence, a workpiece is retrieved from a specific slot in the storage section of the conveying source, and then stored in a specific slot in the storage section at the conveying destination that is currently empty.

[0003] Mapping is performed by non-contactly detecting a workpiece within a receiving compartment using a sensor and determining its position. Among the sensors used in mapping are transmissive sensors that detect the workpiece by blocking the light path, and reflective sensors that irradiate the workpiece with detection light and detect the light reflected from the workpiece's edge (or end face), detecting the workpiece based on the amount or position of reflection. The workpiece is, for example, a semiconductor wafer with a thickness of, for example, 1 mm or less. Furthermore, the spacing between the slots in the receiving compartment where each workpiece is placed is approximately 5 mm to 10 mm. For these reasons, when using either transmissive or reflective sensors, the detection light is preferably a laser with a narrow beam diameter and sharp directionality. Using a transmissive sensor has the advantage of obtaining stable detection results regardless of the workpiece's material, but it requires the sensor to be close to the receiving compartment or the workpiece, potentially causing interference or contact. Additionally, when mounting the sensor on a hand, the hardware structure, such as the hand, needs to be able to transmissively detect the shape of the workpiece. Examples of mapping using transmissive sensors are described in Patent Documents 2 and 3.

[0004] When using reflective sensors, the inventory status of the workpiece can be determined from a position far from the workpiece, thus preventing interference between the sensor and the workpiece and imposing no restrictions on the hardware structure. For example, in the case of a conveying robot, if the sensor can be mounted on the robot's arm or hand, there is no need to design a special shape around the sensor for mapping, thus the use of reflective sensors for mapping has significant advantages in terms of introduction and application. However, in mapping using reflective sensors, the detection accuracy may deteriorate depending on the material, size, and surface condition of the workpiece. Since the absorption of light by the workpiece can be ignored, and if the workpiece surface is rough, light will diffusely reflect, thus enabling reliable workpiece detection. In contrast, for example, in the case of a silicon wafer with a mirror-finished surface, depending on the mapping position where the detection light from the sensor is shone, the detection light may sometimes undergo total internal reflection, in which case the workpiece cannot be properly detected. More specifically, the mapping position refers to the position on the front of the receiving part where the light from the sensor in the workpiece is shone along a direction orthogonal to the first direction (denoted as the second direction) when the sensor is moved in the direction of the slot arrangement (denoted as the first direction) for mapping. The mapping position can be changed by actually moving the sensor in the second direction, or by changing the direction of light from the sensor without changing the sensor's position in the second direction. When using a reflective sensor for mapping, in order to achieve stable detection, the mapping position needs to be adjusted manually while referring to the detection results when the workpiece position is known.

[0005] When storing workpieces in a box-mounted stage, one workpiece needs to be stored in each slot. However, for various reasons, sometimes more than two workpieces are stacked in one slot, or workpieces are placed across two slots. When workpieces are stored in the box-mounted stage in such an incorrect manner (a defective state), removing the workpiece from the stage may result in breakage. Therefore, it is desirable to identify these defective states during mapping and issue alarms to prevent breakage accidents. Such defective states can be determined based on the thickness of the workpiece or its position in the slot detected during mapping. Errors in the determination of the inventory status based on mapping can lead to defects such as the robot picking up a workpiece from a slot where no workpiece is present and stopping due to the error, or repeatedly placing a workpiece in a slot where a workpiece already exists, causing breakage. Since workpiece transport is continuous, accurate mapping over a long period is required.

[0006] [Existing Technical Documents]

[0007] [Patent Literature]

[0008] [Patent Document 1] Japanese Patent Application Publication No. 2019-84651

[0009] [Patent Document 2] Japanese Patent Application Publication No. 2004-327501

[0010] [Patent Document 3] Japanese Patent Application Publication No. 2000-36528 Summary of the Invention

[0011] Mapping using reflective sensors has the advantage of being able to perform mapping without approaching the workpiece or storage area, but depending on the material or surface condition of the workpiece, it is sometimes impossible to accurately determine the inventory status of the workpiece.

[0012] The object of the present invention is to provide a conveying device that can accurately determine the inventory status of workpieces while using a reflective sensor, and a mapping method that can perform mapping accurately in this way.

[0013] When transporting workpieces to a storage unit having multiple slots arranged along a first direction and capable of holding one workpiece in each slot, a mapping process is performed before actual workpiece transport to determine the inventory status of the workpieces in the storage unit. During mapping, a sensor is moved along the first direction to determine whether a workpiece is present in each slot. When using a reflective sensor to prevent interference between the sensor and the workpiece or storage unit during mapping, workpiece detection can sometimes become unstable depending on the shape or material of the workpiece, thus requiring the optimal mapping position to be determined beforehand. This invention automates the determination of the mapping position as a pre-processing step before workpiece transport. Once a mapping position is determined, the same mapping position can be used as long as the shape or material of the workpiece remains unchanged.

[0014] Therefore, the conveying device of the present invention is a conveying device for conveying workpieces to a receiving section having multiple slots arranged in a first direction and capable of receiving one workpiece in each slot. It includes: a hand for holding the workpiece during conveying; a reflective sensor for irradiating the workpiece with light and detecting the reflected light; a moving mechanism for moving the hand and the sensor relative to the receiving section; and a control unit for driving and controlling the moving mechanism. After moving the sensor to a position in the receiving section where one workpiece is received in each slot, the control unit moves the irradiation position of the light from the sensor along a second direction orthogonal to the first direction on the front of the receiving section, repeatedly performing the action of moving the sensor along the first direction and detecting reflected light from the workpiece to acquire detection distribution data, and determining a mapping position based on the detection distribution data. The mapping position is the position of the irradiation position in the workpiece along the second direction when the sensor is moved along the first direction to determine the inventory status of the workpieces in the receiving section.

[0015] The sensor is moved along a second direction orthogonal to the first direction on the front of the receiving section to repeatedly perform the action of moving the sensor along the first direction relative to the receiving section, in which one workpiece is received in each of the slots, and detecting reflected light from the workpiece. This can be described as repeatedly mapping relative to the receiving section at different mapping positions. In this case, data representing the detection intensity of the workpiece at each mapping position and in each slot is obtained from the sensor. This data can be represented as detection distribution data with the mapping position and the slot position as coordinates, respectively. Since it is known that one workpiece is received in each of the slots, based on this, the mapping position in each slot where the workpiece is detected with an appropriate detection intensity can be extracted from the detection distribution data. In the conveying device of the present invention, by determining the mapping position based on the detection distribution data in this way, the inventory status of the workpiece can be accurately determined during the actual conveying of workpieces in actual operation.

[0016] In the conveying device of the present invention, preferably, the control unit moves the sensor along a first direction on the front of the receiving section before acquiring the detection distribution data, and determines the movement range of the sensor along the first direction when acquiring the detection distribution data and when performing mapping. By pre-determining the movement range of the sensor along the first direction, the amount of movement of the sensor along the first direction can be minimized, thereby improving work efficiency. In addition, by pre-determining the movement range along the first direction, it is easy to determine which slot contains the workpiece based on the position of the sensor within that movement range.

[0017] In the conveying device of the present invention, it is preferable that the sensor is mounted on the hand. While mapping requires movement of the sensor, mounting the sensor on the hand, which moves relative to the receiving portion, simplifies the structure of the moving mechanism in the conveying device.

[0018] In the conveying device of the present invention, for example, the workpiece is a plate-shaped object and is horizontally stored in the trough, with the first direction being the vertical direction. Detection by a reflective sensor tends to become unstable when the workpiece is plate-shaped, but according to the conveying method of the present invention, even in this case, a mapping that can reliably determine the inventory status of the workpiece can be performed.

[0019] In the conveying device of the present invention, the control unit can control the mapping of the receiving section using a determined mapping position when controlling the moving mechanism to convey the workpiece. In such a conveying device, when the workpiece is actually conveyed after the mapping position is determined as described above, the inventory status of the workpiece in the receiving section can be accurately determined because mapping is performed at the determined mapping position. In this case, the control unit can also determine the first mapping position and the second mapping position based on the detection distribution data. When mapping, the sensor is moved along the positive direction of the first direction at the first mapping position, and then the sensor is moved along the opposite direction of the first direction at the second mapping position. Since mapping is performed at different mapping positions while the sensor is moved back and forth along the first direction, the increase in the amount of sensor movement can be minimized, and the accuracy of mapping can be improved.

[0020] The mapping method of the present invention is a mapping method for determining the inventory status of workpieces in a storage section. The storage section has multiple slots arranged in a first direction, each capable of storing one workpiece. The mapping method includes: a moving step, in which a reflective sensor is moved to a position in which a workpiece is stored in each of the slots; an acquiring step, after the moving step, in which, on the front side of the storage section, the illumination position of light from the sensor is moved along a second direction orthogonal to the first direction, and the action of moving the sensor along the first direction and detecting reflected light from the workpiece is repeatedly performed to acquire detection distribution data; and a determining step, in which a mapping position is determined based on the detection distribution data. The mapping position is the position along the second direction of the illumination position when the sensor is moved along the first direction for mapping.

[0021] In the mapping method of this invention, in order to determine the optimal mapping position, for a storage unit that holds one workpiece in each of all slots, mapping is repeatedly performed while changing the mapping position, and detection distribution data is obtained based on the data from the sensor at this time. Since it is known that one workpiece is held in each of all slots, the mapping position of the workpiece detected in each slot with an appropriate detection intensity can be extracted from the detection distribution data. In the mapping method of this invention, by determining the mapping position based on the detection distribution data, the inventory status of the workpiece can be accurately determined during the actual workpiece conveying mapping in actual operation.

[0022] In the mapping method of the present invention, preferably, after the moving process and before the determining process, the sensor is moved along a first direction on the front of the receiving part to determine the movement range of the sensor along the first direction during the acquisition process and mapping. By pre-determining the movement range of the sensor along the first direction, the amount of movement of the sensor along the first direction can be minimized, improving work efficiency. Furthermore, by pre-determining the movement range along the first direction, the position of the sensor within that movement range can easily determine which slot contains the workpiece.

[0023] In the mapping method of the present invention, for example, the workpiece is a plate-shaped object and is horizontally stored in a slot, with the first direction being the vertical direction. Detection by a reflective sensor tends to become unstable when the workpiece is plate-shaped, but according to the mapping method of the present invention, even in such cases, mapping can reliably determine the inventory status of the workpiece.

[0024] In the mapping method of the present invention, when transporting the workpiece after the process is determined, the mapping position can be used to map the storage section. In this method, when the workpiece is actually transported after the mapping position is determined, the inventory status of the workpiece in the storage section can be accurately determined because mapping is performed at the determined mapping position. In this case, the first mapping position and the second mapping position can also be determined during the process. During mapping, the sensor is moved along the positive direction of the first direction at the first mapping position, and then the sensor is moved along the opposite direction of the first direction at the second mapping position. Since mapping is performed at different mapping positions while the sensor is moved back and forth along the first direction, the increase in the amount of sensor movement can be minimized, and the mapping accuracy can be improved.

[0025] According to the present invention, it is possible to obtain a conveying device that serves as a conveying device for conveying workpieces and is able to accurately determine the inventory status of workpieces while using a reflective sensor, as well as a mapping method that is able to perform mapping accurately in this way. Attached Figure Description

[0026] Figure 1 This is a diagram showing a conveying robot as an embodiment of the present invention.

[0027] Figure 2 (a) and (b) are top views showing the relationship between the hand, sensor, and workpiece.

[0028] Figure 3 It is a flowchart representing the process of determining the mapping position.

[0029] Figure 4 This is a side view illustrating the lowest point LL and the highest point UL of the mapping.

[0030] Figure 5 These are diagrams illustrating the method for obtaining detection distribution data. (a) is a side view, and (b) is a top view.

[0031] Figure 6 This is a graph representing an example of the distribution data for detection.

[0032] Figure 7 This is the main view representing an example of a mapping path. Detailed Implementation

[0033] The embodiments of the present invention will now be described with reference to the accompanying drawings. Figure 1 A conveying robot is shown as one embodiment of the conveying device of the present invention. Figure 1 The conveying robot 20 shown is used to convey workpieces that are in the form of plates. Hereinafter, the workpiece is a silicon wafer or other wafer 50, which is housed in a cassette stage 40, which serves as a storage unit. The cassette stage 40 has multiple slots arranged along a first direction, specifically in the vertical direction. In this cassette stage 40, one wafer 50 is horizontally housed in each slot. Before conveying the wafer 50, the conveying robot 20 performs a mapping to determine the inventory status of the wafers 50 in the cassette stage 40.

[0034] Figure 1 The conveying robot 20 shown is similar to the horizontal multi-joint robot described in Patent Document 1, and has three arms 22 to 24 mounted in series with respect to the base 21 and a hand 25 mounted at the front end of the arm 24 on the front end side. Figure 1 The image depicts arms 22-24 in a folded state, but they can also be shown unfolded. Specifically, arms 22 and 23 form a linkage mechanism with the front end of arm 23 moving radially in a horizontal plane, centered on the mounting position of arm 22 relative to base 21. Arm 24 can rotate in a horizontal plane relative to arm 23, and hand 25 can rotate relative to arm 24. A lifting mechanism (not shown) for raising and lowering the root-side arm 22 and a rotating mechanism (not shown) for rotating arm 22 about a vertical axis are provided on base 21. A reflective sensor 29 for mapping is mounted on hand 25. A robot controller 30 for driving and controlling the transport robot 20 is also connected to the transport robot 20. The robot controller 30 controls the lifting or rotating mechanism on base 21, the linkage mechanism formed by arms 22 and 23, the mechanism for rotating arm 24 relative to arm 23, and the mechanism for rotating hand 25 relative to arm 24, and processes detection signals from the sensor 29 (described later). Specifically, the robot controller 30 performs controls related to the actions used to determine the mapping position, the mapping actions, and the workpiece transfer actions.

[0035] Figure 2(a) and (b) show the relationship between the hand 25, sensor 29, and wafer 50 during mapping. The hand 25 is an elongated component with a fork 26 at one end, and a reflective sensor 29 is mounted at the other end. The fork 20 has a shape with two branches at its front end and is the part that holds the workpiece, such as the wafer 50, during transport. During transport, the workpiece, which is a plate-like object, is horizontally placed on the surface of the fork 26. The sensor 29 is an integrated unit that emits a laser 60 generated and emitted by a laser diode (LD) or the like, and a light-receiving unit that detects the reflected light when the laser 60 is reflected by the workpiece, such as the wafer 50.

[0036] When the workpiece is wafer 50, the mapping of wafer 50 is performed by moving sensor 29 in the thickness direction of wafer 50 while irradiating laser 60 from sensor 29 onto the end face (wafer edge) of wafer 50, and detecting the reflected light from the end face of wafer 50. The thickness of wafer 50 can also be detected based on the amount of movement of sensor 29 during the detection of reflected light. However, the direction or intensity of the reflected light varies significantly depending on the surface condition of the end face of wafer 50. When the end face of wafer 50 is rough, the irradiated laser 60... Figure 2 As shown in (a), diffuse reflection occurs at the end face of the wafer 50, and a portion of the reflected light from this diffuse reflection reaches the light-receiving portion of the sensor 29. As a result, the sensor 29 can detect the wafer 50 independently of the mapped position. In contrast, if the end face of the wafer 50 is, for example, a mirror surface, ... Figure 2 As shown in (b), the irradiated laser 60 is mirror-reflected in one direction at the end face of the wafer 50. In this case, even if the laser 60 is irradiated onto the wafer 50 with an inappropriate mapping position, the reflected light will not return to the sensor 29, and the sensor 29 may sometimes fail to detect the wafer 50. In this embodiment, the transport robot 20 automatically determines an appropriate mapping position based on the material and shape of the wafer 50 before mapping for transporting the wafer 50.

[0037] The transport robot 20 performs the following processes: taking a wafer 50 from the cassette stage 40 of the transport source and transporting the wafer 50 to the device or cassette stage 40 at the transport destination; and storing the wafer 50 transported from the device or cassette stage 40 of the transport source into an empty slot of the cassette stage 40 at the transport destination. The cassette stage 40, which serves as the storage unit, is a front-opening cassette stage such as the front-opening cassette integrated transport specified by SEMI (Semiconductor Equipment and Materials International) standard E47.1, or a FOUP (Front-Opening Unified Pod) storage box. Therefore, when the transport robot 20 removes the wafer 50 from the slot in the cassette stage 40, and when it stores the wafer 50 relative to the empty slot in the cassette stage 40, the hand 25 of the transport robot 20, with its fork 26 side as the front end, enters the cassette stage 40 through the opening on the front of the cassette stage 40 with the specified slot as the target.

[0038] The determination of the mapping position in this embodiment will be explained. Figure 3 The process of determining the mapping location is shown. Figure 3 Steps 102 to 106 in the process shown are executed by the robot controller 30 controlling the transport robot 20. Since the mapping position needs to be determined according to the shape and material of the wafer 50, in step 101, wafers 50 of the same shape and material as the wafer to be transported are first collected one by one into all the slots of the cassette stage 40, which is the mapping target. Next, in step 102, the cassette stage position for normal wafer transport is taught. In this case, the hand 25 is taught to move to the front of the cassette stage 40, which is the target cassette stage, and is in a standby position, i.e., a position where the hand 25 is ready to enter the cassette stage 40.

[0039] Next, in step 103, the hand 25 is rotated relative to the arm 24 so that the reflective sensor 29 mounted on the hand 25 faces the stage 40. The laser 60 from the sensor 29 illuminates approximately the center of the wafer 50, and the lower end of the lowest slot of the stage 40 is used as the mapping lowest point LL, when the stage 40 is viewed from the front of the opening side. This teaching is for mapping, and the teaching position is registered in the robot controller 30 as the mapping teaching position. Next, the hand 25 is moved vertically upwards, and similarly, the upper end of the uppermost slot of the stage 40 is used as the mapping highest point UL for teaching. Figure 4This is a diagram illustrating the teaching here. The interval between the lowest mapping point LL and the highest mapping point UL, and the interval with a certain margin set at both ends of the interval, are determined as the mapping range. This mapping range is the range of movement of the sensor 29 in the vertical direction, i.e., the range of movement of the hand 25, when the mapping position is determined in step 104 or when the actual mapping is performed after the mapping position is determined.

[0040] Based on the teaching height TL when the hand 25 is taught to the standby position in step 102 and the lowest mapping point LL, the offset between the actual trough height observed from the transport robot 20, or in other words, represented by the coordinate system of the transport robot 20, and the height detected by the illumination of the laser 60 is obtained. This offset is called the mapping offset, and the mapping offset is determined by...

[0041] Mapping offset = LL - TL

[0042] This is represented by the mapping offset. When detecting the wafer 50, the mapping offset can be used to determine which slot the wafer 50 is in below the cassette stage 40. Here, the vertical direction is defined as the Z direction, the direction from the hand 25 in the standby position towards the cassette stage 40 is defined as the Y direction, and the direction orthogonal to the Z direction on the front side of the cassette stage 40 is defined as the X direction. The X and Y directions are in the horizontal plane and are orthogonal to each other.

[0043] By executing steps 101 to 104, the preliminary steps for determining the optimal mapping position are completed. Then, in step 105, the detection distribution data used to determine the mapping position is obtained. Figure 5 Figures (a) and (b) illustrate the acquisition of the detection distribution data. When acquiring the detection distribution data, such as... Figure 5 As shown in (a), for the cassette stage 40 containing wafers 50 in all slots, the sensor 29 is moved along the vertical direction (Z direction) within the mapping range while emitting the laser 60, similar to the mapping performed when transporting the wafers 40, to attempt to detect each wafer 50 within the cassette stage 40. This is referred to as the detection operation. Then, this detection operation is repeatedly performed while moving the sensor 29 along the X direction. Figure 5 (b) The laser 60 from sensor 29 indicates the location in the X-direction where the detection action should be performed. Specifically, a range of, for example, ±10 mm is set in the positive and negative directions of the X-direction, centered on the position in the X-direction where the lowest mapping point LL is determined. Within this range, the detection action is performed while moving sensor 29 in the X-direction at intervals of 0.5 mm to 1 mm. As described later, the optimal mapping position is searched from the positions where the detection action has been performed. Figure 5 In the example shown in (b), the detection action is performed at 11 points A to K in the X direction, where position F is the position when the lowest point LL of the mapping is found.

[0044] In the above description, the detection action is repeatedly performed by moving the sensor 29 in the X direction. However, since the mapping position is the X-direction illumination position of the laser 60 on the chip 50, the detection action can also be repeatedly performed by changing the emission direction of the laser 60 in intervals of 0.2° to 0.4° within a range of ±5° in the horizontal plane while keeping the X-direction position of the sensor 29 (or hand 25) fixed. For example, the emission direction of the laser 60 can be easily changed by changing the angle of the hand 25 relative to the arm 24. Furthermore, in order to improve the determination accuracy of the optimal mapping position, the detection action can also be performed while shifting the position of the sensor 29 in the Y direction within a range of ±5mm.

[0045] While repeatedly performing the detection action by changing the position of the sensor 29 in the X direction, for each slot of the cartridge stage 40 and for each position in the X direction where the detection action was performed, the sensor 29 obtains the detection result as the thickness of the wafer 50 housed in the corresponding slot. The series of detection results obtained in this way can be represented as two-dimensional detection distribution data with the position in the X direction as one dimension and the position of the slot in the Z direction as the other dimension. Figure 6 The diagram shows an example of detection distribution data obtained when the number of slots in the substrate stage 40 is 10, numbered sequentially from 1 to 10 from bottom to top, and the detection positions in the X direction are the 11 locations A to K mentioned above. Each slot contains a silicon wafer 50 with a thickness of 0.9 mm. The areas indicated in black in the diagram are the areas where the sensor 29 detects the wafer 50. The larger the dimension of the area in the Z direction (vertical direction in the diagram), the thicker the detected wafer 50. Dashed lines indicate wafers 50 that were present but not detected. The actual thickness of the wafer 50 detected at each position in the X direction and at each position in the slot is shown in Table 1. The units of the values ​​in Table 1 are in mm.

[0046] Table 1

[0047]

[0048] After obtaining the detection distribution data, in step 106, the mapping position in the X direction used during actual transportation is determined based on the detection distribution data. The following explains how the mapping position is determined based on the detection distribution data.

[0049] exist Figure 6In the example shown in Table 1, since the 0.9mm thick wafers 50 are housed in the slots of the cassette stage 40, the X-direction position where the thickness is 0.9mm is detected in all slots is the most suitable as the mapping position. If we examine the results in Table 1 from this perspective, at positions A, B, and K, although there are actually 10 wafers 50 on the cassette stage 40, some wafers 50 cannot be detected. This can be attributed to the fact that, because the laser 60's irradiation position is far from the center of the wafer 50 along the X-direction, the laser 60 cannot be correctly reflected from the end face of the wafer 60, thus preventing accurate detection of the wafer 50. Since the mapping result is unreliable, mapping should not be performed at these positions A, B, and K.

[0050] At positions F, G, and H, although the actual thickness of wafer 50 is approximately 1 mm, grooves with a thickness of 2 mm to 4 mm were detected. Furthermore, even when wafers 50 of the same thickness were being detected, a deviation of more than twice was observed in the detected thickness. This can be attributed to overreflection due to the reflection angle of the laser 60 within wafer 50. In this state, since detecting wafer overlap within the groove based on the detected wafer thickness is unreliable, mapping at these positions F, G, and H should not be performed.

[0051] Since positions A, B, F, G, H, and K are not suitable as mapping positions, a suitable position in the X direction for mapping is selected from the remaining positions C, D, E, I, and J as the mapping position. Here, position D or position I is determined as the mapping position. After the mapping position is determined in this way, the teaching position previously registered as the position for mapping in step 103 is automatically corrected to the mapping position determined this time. As conditions for determining the mapping position, the following (1) to (3) can be cited.

[0052] (1) The average thickness of the detected thickness is closest to the specified thickness (e.g., the thickness of wafer 50);

[0053] (2) Minimal deviation in all thickness values ​​detected;

[0054] (3) The difference between the maximum and minimum values ​​of the detected thickness is the smallest.

[0055] When determining the mapping position, any one of conditions (1) to (3) can be used, or two of these conditions can be used, or all of conditions (1) to (3) can be used. In addition, in the above, the detection action is performed while shifting the position in the X direction, but the detection action can also be performed while shifting the axial angle of the hand 25 relative to the arm 24 or the Y direction position of the sensor 29, to find the axial angle or Y direction position that can obtain a stable detection result, and at least one of the axial angle and Y direction position of the hand 25 is combined with the X direction position to obtain the mapping position.

[0056] The optimal mapping position for mapping the inventory status of the wafer 50 in the discrimination cassette stage 40 is determined by performing steps 101 to 106. Once the mapping position is determined in this way, the mapping is then performed at that determined mapping position when the transport robot 20 is actually used to transport the wafer 50. In order to move the hand 25 to the center position of the wafer 50 in the X direction so that the laser 60 irradiates the wafer 50, the teaching position registered as the mapping position in step 103 is corrected in step 106 to the mapping position determined as described above, so that the actual mapping during transport can be performed by moving the hand 25 to the teaching position registered for mapping.

[0057] To complete the mapping in the shortest possible time, the sensor 29 is moved up or down once within the mapping range at a predetermined mapping position to perform a detection action. However, to further improve the mapping accuracy, the sensor 29 can be moved using a combination of upward and downward reciprocating movements to perform the detection action, and the detection values ​​for the forward and return paths can be averaged. In the case of reciprocating motion-based mapping, it is preferable to perform detection actions at different mapping positions on the forward and return paths after determining two different mapping positions in step 106. Figure 6 In the example shown in Table 1, where positions D and J are determined as mapping positions, such as Figure 7 As shown, a detection action is performed at mapping position D when sensor 29 rises and at mapping position J when it falls. Then, the detection results are averaged across each slot to obtain the final mapping result. Figure 7 In the diagram, the thick line 70 represents the trajectory of the irradiation position of laser 60.

[0058] In the transport robot 20 of this embodiment described above, by changing its position in the X direction while performing a detection operation on the cassette stage 40 containing wafers 50 in all slots, detection distribution data is acquired, and the optimal mapping position is automatically determined based on this detection distribution data. Furthermore, the determined mapping position is used during the subsequent actual transport of the wafers 50. As a result, without the need for manual adjustment of the mapping position, the mapping to accurately determine the inventory status of the wafers 50 in the cassette stage 40 can be performed using a reflective sensor.

[0059] Figure Labels

[0060] 20…Transportation robot; 21…Base; 22-24…Arm; 25…Hand; 26…Fork; 29…Sensor; 30…Robot controller; 40…Box placement stage; 50…Chip; 60…Laser; 70…Mapping path.

Claims

1. A conveying device that conveys workpieces by means of a receiving portion having a plurality of slots arranged along a first direction and capable of receiving workpieces, one by one, of the same shape and material as the workpiece to be conveyed into each of the slots, characterized in that, have: Hold the hand holding the workpiece while conveying it; A reflective sensor that detects reflected light by illuminating the workpiece; A moving mechanism that moves the hand and the sensor relative to the storage portion; and The control unit that drives and controls the moving mechanism. After the control unit moves the sensor to a position where a workpiece is housed in each of the slots, it moves the position of the light irradiated by the sensor in the workpiece along a second direction orthogonal to the first direction on the front of the housing part. This is repeated to move the sensor along the first direction and detect the reflected light from the workpiece, thereby acquiring two-dimensional detection distribution data that represents the thickness detection result of the workpiece housed in the slots. This data uses the position of the detection action in the second direction as one dimension and the position of the slot in the first direction as the other. The mapping position is then determined based on this detection distribution data. The mapping position is the position of the irradiation position along the second direction when the sensor moves along the first direction to map the inventory status of the workpiece in the storage section.

2. The conveying device according to claim 1, characterized in that, Before acquiring the detection distribution data, the control unit moves the sensor along the first direction on the front of the receiving part to determine the range of movement of the sensor along the first direction when acquiring the detection distribution data and when performing the mapping.

3. The conveying device according to claim 1 or 2, characterized in that, The sensor is mounted on the hand.

4. The conveying device according to claim 1 or 2, characterized in that, The workpiece is a plate-shaped object and is horizontally housed in the groove, with the first direction being the vertical direction.

5. The conveying device according to claim 1 or 2, characterized in that, When the control unit controls the moving mechanism to transport the workpiece, it performs control over the mapping of the receiving part using the determined mapping position.

6. The conveying device according to claim 5, characterized in that, The control unit determines a first mapping position and a second mapping position based on the detection distribution data. During the mapping process, the sensor is moved at the first mapping position along the positive direction of the first direction, and then the sensor is moved at the second mapping position along the opposite direction of the first direction.

7. A mapping method for determining the inventory status of workpieces in a receiving section, the receiving section having a plurality of slots arranged in a first direction and capable of receiving workpieces, one by one, of the same shape and material as the workpiece to be transported, into each of the slots, characterized in that... have: The moving process moves the reflective sensor toward the position of the receiving part, in which one of the workpieces is received in each of the slots; In the acquisition process, after the moving process, the position of the light irradiated by the sensor in the workpiece is moved along a second direction orthogonal to the first direction on the front of the receiving part. The action of moving the sensor along the first direction and detecting the reflected light from the workpiece is repeatedly performed to acquire two-dimensional detection distribution data, which is the thickness detection result of the workpiece received in the groove, with the position of the detection action in the second direction as one dimension and the position of the groove in the first direction as the other dimension. and The process is determined by specifying the mapping position based on the detection distribution data. The mapping position is the position of the illumination position along the second direction when the sensor is moved along the first direction to perform the mapping.

8. The mapping method according to claim 7, characterized in that, After the moving step and before the deciding step, the sensor is moved along the first direction from the front of the receiving part to determine the range of movement of the sensor along the first direction during the acquiring step and the mapping.

9. The mapping method according to claim 7 or 8, characterized in that, The workpiece is a plate-shaped object and is horizontally housed in the groove, with the first direction being the vertical direction.

10. The mapping method according to claim 7 or 8, characterized in that, When the workpiece is transported after the decision-making process, the mapping position is used to map the receiving part.

11. The mapping method according to claim 10, characterized in that, In the decision-making process, a first mapping position and a second mapping position are determined. During the mapping, the sensor is moved at the first mapping position along the positive direction of the first direction, and then the sensor is moved at the second mapping position along the opposite direction of the first direction.

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