Wafer Aligner

Abstract

To provide an excellent wafer aligner.SOLUTION: A wafer aligner 1 comprises: a first chuck 10 configured to open / close along a reference plane in parallel with the principal surface of a delivered wafer and, when closed, grasp a peripheral part of the wafer to swivel around a central axis vertical to the reference plane; a second chuck 20 configured to open / close along the reference plane and, when closed, hold the peripheral part of the wafer; a detection sensor 60 configured to detect markings on the wafer; and a controller 70 configured to make the first chuck 10 close and grasp the wafer when the wafer is delivered, swivel the first chuck 10 on the basis of output of the detection sensor 60 so that the wafer is in a predetermined circumferential position, make the second chuck 20 close and hold the wafer, make the first chuck 10 open and release the wafer, and swivel the first chuck 10 up to a first prescribed position.SELECTED DRAWING: Figure 2

Description

[Technical field]

[0001] The present invention relates to a wafer aligner. [Background technology]

[0002] Generally, when handling semiconductor wafers in substrate inspection equipment, semiconductor manufacturing equipment, etc., a wafer aligner is used to align the orientation of the wafer based on a notch, orientation flat, etc. For example, Patent Document 1 discloses technology relating to such a wafer aligner. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2003-243294 A Summary of the Invention [Problem to be solved by the invention]

[0004] An object of the present invention is to provide an excellent wafer aligner. [Means for solving the problem]

[0005] According to one aspect of the present invention, a wafer aligner includes a first chuck configured to open and close along a reference plane parallel to a main surface of a wafer to be loaded, to grip a peripheral portion of the wafer when closed, and to rotate about a central axis perpendicular to the reference plane; a second chuck configured to open and close along the reference plane and to hold the peripheral portion of the wafer when closed; a detection sensor configured to detect marks on the wafer; and a control device configured to, when the wafer is loaded, close the first chuck to grip the wafer, then rotate the first chuck based on an output of the detection sensor so that the wafer is at a predetermined circumferential position, then close the second chuck to hold the wafer and open the first chuck to release the wafer, and then rotate the first chuck to a first predetermined position. Effect of the Invention

[0006] According to the present invention, an excellent wafer aligner can be provided. [Brief description of the drawings]

[0007] [Figure 1] FIG. 1 is an external view showing a schematic configuration example of a wafer aligner according to an embodiment. [Diagram 2] FIG. 2 is a diagram illustrating an outline of a configuration example of a wafer aligner according to an embodiment. [Figure 3A] FIG. 3A is a schematic diagram showing the first chuck and the second chuck in a standby position waiting to receive a wafer. [Figure 3B] FIG. 3B is a diagram illustrating a state in which the first chuck is closed and the second chuck is open. [Figure 3C] FIG. 3C is a diagram illustrating a state in which the second chuck is closed and the first chuck is open. [Figure 4] FIG. 4 is a flow chart outlining an example of the operation of the wafer aligner controlled by the control device. [Figure 5A]FIG. 5A is a diagram showing an overview when a wafer is being carried in by a transfer robot. [Figure 5B] FIG. 5B is an enlarged view of the boxed area shown in FIG. 5A. [Figure 6A] FIG. 6A is a schematic diagram of the wafer aligner when the first chuck is closed and the second chuck is open. [Figure 6B] FIG. 6B is an enlarged view of the boxed area shown in FIG. 6A. [Figure 7A] FIG. 7A is a schematic diagram of the wafer aligner when the notch is detected. [Figure 7B] FIG. 7B is an enlarged view of the boxed area shown in FIG. 7A. [Figure 7C] FIG. 7C is an enlarged view of the boxed area shown in FIG. 7A. [Figure 8A] FIG. 8A is a diagram showing an overview when the second chuck is closed and the first chuck is opened. [Figure 8B] FIG. 8B is an enlarged view of the boxed area shown in FIG. 8A. [Figure 8C] FIG. 8C is an enlarged view of the boxed area shown in FIG. 8A. [Figure 9A] FIG. 9A is a schematic diagram of the wafer aligner with the first chuck returned to its initial position. [Figure 9B] FIG. 9B is an enlarged view of the boxed area shown in FIG. 9A. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0008] An embodiment will be described with reference to the drawings. The embodiment relates to a wafer aligner for aligning the circumferential position of a wafer based on a mark such as a notch or an orientation flat. The diameter of the wafer may be, but is not limited to, 200 mm or 300 mm. The wafer aligner of the embodiment achieves reduced damage to the wafer, high operational reliability, and fast throughput, compared to conventional wafer aligners.

[0009] [Wafer aligner configuration] FIG. 1 is an external view showing an outline of a configuration example of a wafer aligner 1 according to this embodiment. The wafer aligner 1 includes a plurality of first chucks 10 and second chucks 20 each supporting a wafer 90. The first chucks 10 and second chucks 20 are configured to support the peripheral portion of a disk-shaped wafer 90, and are provided around the position where the wafer 90 is placed. In the example shown in FIG. 1, three first chucks 10 and three second chucks 20 are provided, and the first chucks 10 and the second chucks 20 are each evenly arranged around the position where the wafer 90 is placed. The first chucks 10 or the second chucks 20 may be arranged in any manner, and four or more chucks may be provided.

[0010] Known marks for indicating the circumferential position of the wafer 90 include a notch and an orientation flat. In this embodiment, a notch is used as an example of such a mark. In this embodiment, the wafer aligner 1 includes a detection sensor 60 for detecting the notch 91 of the wafer 90. The detection sensor 60 is, for example, an optical sensor.

[0011] 5A, the wafer 90 is carried into the wafer aligner 1 by the transfer robot 81 and placed on the first chuck 10 so that its main surface is horizontal. The wafer aligner 1 grips the wafer 90 with the first chuck 10 and rotates it in the circumferential direction while searching for the notch 91 using the detection sensor 60 and aligns the wafer 90 based on the position of the notch 91. The aligned wafer 90 is carried out of the wafer aligner 1 by the transfer robot 81.

[0012] In the following explanation, the reference plane is horizontal, the wafer 90 is positioned so that its main surface is horizontal, and the direction equivalent to the circumferential direction of the wafer 90 when positioned is described as the circumferential direction of the wafer aligner 1, and the direction equivalent to the radial direction of the wafer 90 is described as the radial direction of the wafer aligner 1.

[0013] Fig. 2 is a diagram showing a schematic overview of an example of the configuration of the wafer aligner 1. In Fig. 2, only two first chucks 10 and two second chucks 20 are shown.

[0014] The first chuck 10 is supported by a first arm 41 extending horizontally in the radial direction. The first arm 41 can be displaced outward or inward horizontally in the radial direction by a first opening / closing mechanism 51. That is, the first chuck 10 can be displaced outward to open or inward to close horizontally in the radial direction. Although the configurations of the first arm 41 and the first opening / closing mechanism 51 are not limited to those described above, the first chuck 10 is configured to open and close horizontally in the radial direction.

[0015] The first opening and closing mechanism 51 is configured to be able to rotate horizontally around a central axis 31 that is provided vertically by the rotating mechanism 32. That is, the first chuck 10 is configured to be able to rotate horizontally around the central axis 31. Although the configurations of the rotating mechanism 32, the first arm 41, and the first opening and closing mechanism 51 are not limited to those described above, the first chuck 10 is configured to rotate around a vertical central axis.

[0016] The second chuck 20 is supported by a second arm 42 extending horizontally in the radial direction. The second arm 42 can be displaced outward or inward horizontally in the radial direction by a fixed second opening / closing mechanism 52. That is, the second chuck 20 can be displaced outward to open or inward to close horizontally in the radial direction. Although the configurations of the second arm 42 and the second opening / closing mechanism 52 are not limited to those described above, the second chuck 20 is configured to open and close horizontally in the radial direction.

[0017] All the first opening / closing mechanisms 51 and the second opening / closing mechanisms 52 are interlocked by the interlocking mechanism 53. As a result, as described below, all the first chucks 10 and the second chucks 20 are interlocked. For example, when the first chucks 10 grip the wafer 90, all the first chucks 10 are displaced inward to close, and at this time, all the second chucks 20 are displaced outward to open. When the second chucks 20 hold the wafer 90, all the second chucks 20 are displaced inward to close, and when the second chucks 20 hold the wafer 90, then all the first chucks 10 are displaced outward to open. Such mechanisms relating to the first opening / closing mechanisms 51, the second opening / closing mechanisms 52, and the interlocking mechanism 53 can be appropriately configured using links, gears, cams, springs, and the like.

[0018] The interlocking mechanism 53 is driven by an opening / closing motor 54 serving as a drive unit. The opening / closing motor 54 may be, for example, a geared motor. The operation of the opening / closing motor 54 is controlled by a control device 70. An encoder (not shown) or the like may be provided, and the opening / closing motor 54 may be a servo motor. In this embodiment, all of the first chucks 10 and the second chucks 20 are operated by one drive unit that operates the interlocking mechanism 53.

[0019] The turning mechanism 32 is driven by a turning motor 33. The turning motor 33 may be, for example, a pulse motor. The operation of the turning motor 33 is controlled by a control device 70. An encoder (not shown) or the like may be provided, and the turning motor 33 may be a servo motor.

[0020] The control device 70 includes an integrated circuit such as a central processing unit (CPU) or a field programmable gate array (FPGA). As described above, the control device 70 controls the operation of the opening / closing motor 54 and the turning motor 33 to control the operation of the first chuck 10 and the second chuck 20. The control device 70 acquires information on the detection result such as the presence or absence of detection of the notch 91 from the detection sensor 60. The control device 70 controls the operation of the first chuck 10 and the second chuck 20 based on the information from the detection sensor 60. The control device 70 cooperates with a transfer robot control unit 82 that controls a transfer robot 81 to operate the wafer aligner 1.

[0021] The opening and closing operations of the first chuck 10 and the second chuck 20 will be further described with reference to Figs. 3A to 3C. Fig. 3A is a schematic diagram showing the first chuck 10 and the second chuck 20 in a standby position when waiting to receive a wafer 90. The first chuck 10 has a wafer mounting surface 11 that is gently inclined upward with respect to a horizontal plane so that the outer side is vertically upward. A gripping surface 12 that forms a vertical wall surface is provided at the outer end of the wafer mounting surface 11. When the wafer 90 is carried in by the transfer robot 81, the wafer 90 is mounted on the wafer mounting surface 11. The first chuck 10 supports the peripheral portion of the wafer 90 from below on the wafer mounting surface 11.

[0022] FIG. 3B is a schematic diagram showing a state in which the first chuck 10 is closed and the second chuck 20 is opened by the interlocking mechanism 53, the first opening / closing mechanism 51, and the second opening / closing mechanism 52. When the first chuck 10 is closed, the first arm 41 is moved radially inward by the first opening / closing mechanism 51 from the state shown in FIG. 3A, and the first chuck 10 supported by the first arm 41 also moves horizontally radially inward. Since the wafer mounting surface 11 of the first chuck 10 is gently inclined, when the first chuck 10 is closed, the peripheral portion of the wafer 90 moves smoothly on the wafer mounting surface 11. When the peripheral portion of the wafer 90 reaches the outer periphery of the wafer mounting surface 11, the peripheral portion of the wafer 90 hits the vertical gripping surface 12 of the first chuck 10. For example, a force is applied to the first chuck 10 in the radially inward direction by a tension spring or the like provided in the first opening / closing mechanism 51. As a result, a force is applied to the peripheral portion of the wafer 90 from the vertical gripping surface 12 of the first chuck 10. This force is applied horizontally to the wafer 90. In this manner, the wafer 90 is gripped at its peripheral portion by the vertical gripping surface 12 of the first chuck 10.

[0023] 3C is a schematic diagram showing a state in which the second chuck 20 is closed and the first chuck 10 is open. The second chuck 20 has a wafer holding surface 21 that is inclined upward with respect to the horizontal plane so that the outer side is vertically upward. The wafer holding surface 21 is provided with holding positions 22 where the inclination changes. The wafer holding surface 21 is inclined upward with respect to the horizontal plane more significantly outside the holding position 22 than inside the holding position 22.

[0024] First, the second arm 42 moves radially inward by the interlocking mechanism 53, the second opening / closing mechanism 52, and the first opening / closing mechanism 51, and the second chuck 20 supported by the second arm 42 also moves radially inward. Eventually, the holding position 22 of the second chuck 20 reaches the peripheral portion of the wafer 90, and the wafer 90 is placed on the wafer holding surface 21 of the second chuck 20 at the holding position 22 and is held by the second chuck 20. Thereafter, the first arm 41 moves radially outward, and the first chuck 10 supported by the first arm 41 also moves radially outward. When the wafer 90 is held by the second chuck 20 at the holding position 22, no inward force is applied from the second opening / closing mechanism 52 to the second chuck 20. Therefore, no horizontal force acts on the wafer 90, and the wafer 90 is only supported by the second chuck 20 against gravity.

[0025] Since the wafer holding surface 21 is inclined so as to be vertically upward toward the outside even outside the holding position 22, when the wafer 90 is lifted by the transfer robot 81, the peripheral portion of the wafer 90 does not rub against the wafer holding surface 21.

[0026] [Wafer aligner operation] Fig. 4 is a flow chart outlining an example of the operation of the wafer aligner 1 controlled by the control device 70. The operation of the wafer aligner 1 will be described with reference to Fig. 4 and other drawings.

[0027] In step S1, the control device 70 moves the first chuck 10 and the second chuck 20 to a standby position. The standby positions of the first chuck 10 and the second chuck 20 are positions where the first chuck 10 and the second chuck 20 wait for the transfer robot 81 to carry in the wafer 90. The circumferential position of the first chuck 10 is a position beside the second chuck 20 as shown in FIG. 1 so as not to collide with the transfer robot 81. The radial positions of the first chuck 10 and the second chuck 20 are positions where the wafer 90 is mounted on the wafer mounting surface 11 of the first chuck 10 as shown in FIGS. 1 and 3A.

[0028] In step S2, the control device 70 determines whether the wafer 90 has been carried in. The control device 70 can determine whether the wafer 90 has been carried in by, for example, acquiring information from the transfer robot control unit 82. The wafer aligner 1 may also be provided with a sensor for detecting that the wafer 90 has been carried in, and it may be determined whether the wafer 90 has been carried in based on the output of this sensor. The process waits until the wafer 90 has been carried in.

[0029] FIG. 5A is a diagram showing an overview when the wafer 90 is carried in by the transport robot 81. FIG. 5B is an enlarged view of the enclosed portion shown in FIG. 5A. The transport robot 81 carries in the wafer 90 horizontally, for example, so that the wafer 90 passes slightly above the first chuck 10 and the second chuck 20, and lowers the wafer 90 directly below the wafer 90 at a position where the center of the wafer 90 is almost aligned directly above the central axis 31 of the wafer aligner 1. As a result, the wafer 90 is mounted on the wafer mounting surface 11 of the first chuck 10. At this time, as shown in FIG. 5B and FIG. 3A, the first chuck 10 supports the wafer 90 from below on the wafer mounting surface 11 but does not grip it, and the second chuck 20 does not contact the wafer 90. When the wafer 90 is mounted on the first chuck 10, the transport robot 81 retreats. Since the first chuck 10 is in the standby position in the circumferential direction, the transfer robot 81 can carry in the wafer 90 without coming into contact with the first chuck 10.

[0030] When it is determined in step S2 that the wafer 90 has been loaded, the process proceeds to step S3. In step S3, the control device 70 operates the opening / closing motor 54 to close the first chuck 10 via the interlocking mechanism 53 and the first opening / closing mechanism 51, and to open the second chuck 20 in conjunction with the interlocking mechanism 53 and the second opening / closing mechanism 52.

[0031] Fig. 6A is a diagram showing an overview when the first chuck 10 is closed and the second chuck 20 is open. Fig. 6B is an enlarged view of the enclosed portion shown in Fig. 6A. As shown in Fig. 6B and Fig. 3B, the first chuck 10 grips the peripheral portion of the wafer 90 with the gripping surface 12. At this time, the second chuck 20 is not in contact with the wafer 90 because it is open.

[0032] In step S4, the control device 70 operates the rotation motor 33 to rotate the first chuck 10 in the circumferential direction. That is, the wafer 90 is rotated in the circumferential direction. In step S5, the control device 70 determines, based on the output of the detection sensor 60, whether or not the notch 91 has reached the position of the detection sensor 60 and been detected. Until the notch 91 is detected, the processes of steps S4 and S5 are repeated, and the wafer 90 is rotated in the circumferential direction.

[0033] When it is determined in step S5 that the notch 91 has been detected, in step S6, the control device 70 stops the rotation of the first chuck 10 in the circumferential direction. FIG. 7A is a diagram showing an outline of the wafer aligner 1 when the notch 91 has been detected. FIGS. 7B and 7C are enlarged views of the enclosed portion shown in FIG. 7A. At this time, the first chuck 10 gripping the wafer 90 has moved to a position separated in the circumferential direction from the second chuck 20 not touching the wafer 90. At this time, the circumferential position of the wafer 90 is a position where the notch 91 coincides with the position of the detection sensor 60. If the target circumferential position of the wafer 90 is this position, this position may be left as it is, or if the target circumferential position of the wafer 90 is different, the control device 70 further rotates the first chuck 10 in the circumferential direction by a predetermined amount to that position.

[0034] Thereafter, in step S7, the control device 70 operates the opening / closing motor 54. At this time, the second chuck 20 is closed via the interlocking mechanism 53 and the second opening / closing mechanism 52 operated by the opening / closing motor 54, and the second chuck 20 receives the wafer 90. Subsequently, the first chuck 10 is opened in interlocking with the interlocking mechanism 53 and the first opening / closing mechanism 51, and the first chuck 10 releases the wafer 90.

[0035] Fig. 8A is a diagram showing an overview when the second chuck 20 is closed and the first chuck 10 is open. Fig. 8B and Fig. 8C are enlarged views of the enclosed portion shown in Fig. 8A, respectively. As shown in Fig. 8B, Fig. 8C and Fig. 3C, the second chuck 20 supports the peripheral portion of the wafer 90 at the holding position 22. At this time, the first chuck 10 is not in contact with the wafer 90 because it is open.

[0036] In step S8, the control device 70 operates the rotation motor 33 to rotate the first chuck 10, which is not gripping the wafer 90, in the circumferential direction and return it to the initial position, which is the same as the standby position. FIG. 9A is a diagram showing an outline of the wafer aligner 1 in a state in which the first chuck 10 has returned to the initial position. FIG. 9B is an enlarged view of the enclosed portion shown in FIG. 9A. The circumferential position of the first chuck 10 is a position beside the second chuck 20, which is the same as the standby position, and is a position where it will not collide with the transfer robot 81 that carries out the wafer 90. When the first chuck 10 reaches the initial position, the control device 70 transmits information to that effect to the transfer robot control unit 82. The wafer aligner 1 waits in this position for the transfer robot 81 to carry out the wafer 90.

[0037] Conversely, when the transfer robot 81 carries in the wafer 90, it enters under the wafer 90 and scoops up the wafer 90 from below straight up. At this time, the wafer 90 is placed on the holding position 22 of the second chuck 20, and since the wafer holding surface 21 outside the holding position 22 has a shape that opens upward and outward, the wafer 90 is lifted up without hitting other parts of the second chuck 20. The transfer robot 81 carries out the wafer 90 from the wafer aligner 1 and stores the wafer 90 in a predetermined position.

[0038] In step S9, the control device 70 judges whether the wafer 90 has been carried out. When it is judged that the wafer 90 has not been carried out, the control device 70 waits until the wafer 90 has been carried out. When it is judged that the wafer 90 has been carried out, the control device 70 judges in step S10 whether the process is to be ended. That is, it judges whether the process for the next wafer 90 is to be performed. When it is judged that the process is not to be ended and that the process for the next wafer 90 is to be performed, the process returns to step S1. That is, the first chuck 10 and the second chuck 20 are displaced in the radial direction to the standby position, and the process of steps S1 to S9 described above is repeated. When it is judged that the process is to be ended in step S10, the series of processes is ended.

[0039] [About the wafer aligner] Conventionally known wafer aligners, including the wafer aligner disclosed in Patent Document 1 (JP Patent Publication 2003-243294A), generally have a configuration in which at least one of an alignment chuck (corresponding to the first chuck 10 in this embodiment) that grips the wafer when rotating and a support (corresponding to the second chuck 20 in this embodiment) that supports the wafer when the chuck releases the wafer, is displaced up and down. In contrast, in the wafer aligner 1 of this embodiment, both the first chuck 10 and the second chuck 20 are displaced only in the horizontal direction, and are not displaced up and down. This provides various advantages.

[0040] For example, in a conventional aligner, a transfer operation is performed in which the alignment chuck opens to release the wafer, and the alignment chuck or the support moves up and down to support the wafer. During this transfer operation, there is a possibility that the wafer may become eccentric. Furthermore, if the wafer is largely eccentric, this may cause the wafer to tilt during the transfer operation. Furthermore, the vertical movement during the transfer operation causes the peripheral portion of the wafer to slide against the support, resulting in rubbing.

[0041] In contrast, in the wafer aligner 1 of this embodiment, neither the first chuck 10 nor the second chuck 20 moves up and down during the transfer operation, and the second chuck 20 first supports the wafer 90, and then the first chuck 10 opens. As a result, no decentering of the wafer occurs during the transfer operation. Also, no rubbing occurs at the peripheral edge of the wafer 90 during the transfer. For these reasons, there is no risk of damage to the wafer 90 during the transfer operation.

[0042] In addition, in the wafer aligner 1 of this embodiment, the first chuck 10 and the second chuck 20 do not move up and down, and the opening and closing of the first chuck 10 and the second chuck 20 are linked by the linkage mechanism 53, so one axis is less than that of a conventional aligner involving up and down movement. As a result, compared to a conventional aligner, the wafer aligner 1 of this embodiment has a simplified mechanism, can reduce costs, is less likely to malfunction, has high operational reliability, and consumes less power during operation. In addition, in the wafer aligner 1 of this embodiment, the operation sequence can be simplified because it operates on only two axes, the opening and closing operation of the first chuck 10 and the second chuck 20 and the rotation operation of the first chuck 10.

[0043] Furthermore, in conventional aligners, the above-mentioned up and down movement is performed at least twice per processing of one wafer, but in the wafer aligner 1 of this embodiment, this up and down movement is not required, and there is no acceleration or deceleration related to the up and down movement, resulting in faster throughput.

[0044] In the above embodiment, the wafer 90 is carried into and out of the wafer aligner 1 by the transport robot 81, but this is not limiting. According to the wafer aligner 1 of this embodiment, a large space can be provided around the wafer 90 when the wafer 90 is placed on the first chuck 10, so that the wafer can be carried in manually by an operator. That is, the operator may manually place the wafer 90 on the first chuck 10 of the wafer aligner 1 using wafer tweezers.

[0045] According to the wafer aligner 1 of this embodiment, the chuck area can be increased to make the chuck position easier to see. In addition, there is no vertical movement of the wafer 90 during operation, and only the opening and closing of the first chuck 10 and the second chuck 20 and the rotation of the first chuck 10 are performed, so the operation is gentle and operator-friendly.

[0046] Although the present invention has been described above by showing preferred embodiments, it goes without saying that the present invention is not limited to the above-described embodiments, and various modifications can be made within the scope of the present invention. [Explanation of symbols]

[0047] 1: Wafer aligner 10: first chuck, 11: wafer mounting surface, 12: gripping surface 20: second chuck, 21: wafer holding surface, 22: holding position 31: central axis, 32: rotation mechanism, 33: rotation motor 41: 1st arm, 42: 2nd arm 51: first opening / closing mechanism, 52: second opening / closing mechanism, 53: interlocking mechanism, 54: opening / closing motor 60: Detection sensor 70: Control device 81: Transport robot, 82: Transport robot control unit 90: wafer, 91: notch

Claims

1. a first chuck configured to open and close along a reference plane parallel to a main surface of a wafer to be loaded, to grip a peripheral portion of the wafer when closed, and to rotate about a central axis perpendicular to the reference plane; a second chuck configured to open and close along the reference surface and to hold a peripheral edge of the wafer when closed; a detection sensor configured to detect indicia provided on the wafer; a control device configured to, when the wafer is carried in, close the first chuck to grip the wafer, then rotate the first chuck based on the output of the detection sensor so that the wafer is at a predetermined circumferential position, then close the second chuck to hold the wafer, then open the first chuck to release the wafer, and then rotate the first chuck to a first predetermined position; an interlocking mechanism that mechanically interlocks the opening and closing of the first chuck with the opening and closing of the second chuck; A drive unit that operates the interlocking mechanism; A wafer aligner comprising:

2. a first chuck configured to open and close along a reference plane parallel to a main surface of a wafer to be loaded, to grip a peripheral portion of the wafer when closed, and to rotate about a central axis perpendicular to the reference plane; a second chuck configured to open and close along the reference surface and to hold a peripheral edge of the wafer when closed; a detection sensor configured to detect indicia provided on the wafer; a control device configured to, when the wafer is carried in, close the first chuck to grip the wafer, then rotate the first chuck based on the output of the detection sensor so that the wafer is at a predetermined circumferential position, then close the second chuck to hold the wafer, then open the first chuck to release the wafer, and then rotate the first chuck to a first predetermined position; a transfer robot configured to remove the wafer held by the second chuck; Equipped with the first predetermined position is a position where the first chuck does not collide with the transfer robot, The control device is configured to rotate the first chuck to the first predetermined position and then cause the transfer robot to unload the wafer. Wafer aligner.

3. The reference plane is a horizontal plane, the first chuck having a vertical gripping surface configured to grip a peripheral edge of the wafer; the second chuck has a wafer holding surface inclined with respect to the horizontal plane so that the outer side is vertically upward so that the wafer held by the second chuck can be moved vertically upward.

3. The wafer aligner according to claim 1 or 2.

4. 4. The wafer aligner according to claim 3, wherein the first chuck has a wafer mounting surface connected to an inner side of the gripping surface and inclined with respect to the horizontal plane so that the outer side is vertically upward.

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