JP2024020815A - Wafer transfer device - Google Patents

Abstract

An object of the present invention is to improve the accuracy of conveying a wafer to a polishing stage. A wafer transfer device includes a first slider driven in a first direction by a first actuator, and a second slider driven in a second direction intersecting the first direction by a second actuator. . The wafer transport device includes a transport hand that is attached to the second slider and grips the wafer to be transported to the polishing stage. The wafer transfer device includes a control system that controls the first actuator to move the transfer hand in the first direction by a target distance to transfer the wafer to the polishing stage. The wafer transfer device includes a measurement device that is communicatively connected to the control system and measures outer edge data of the wafer transferred to the polishing stage. [Selection diagram] Figure 10

Description

The present invention relates to a wafer transport device that transports a wafer to a polishing stage.

In the manufacturing process of semiconductor devices, electronic circuits are formed on wafers such as silicon wafers. The wafer, which is a semiconductor material, is not only subjected to a polishing process to polish the surface of the wafer, but also a polishing process to polish the outer edge of the wafer to prevent chipping during handling (patented). (See Reference 1).

JP2009-297842A

By the way, when polishing the outer edge of a wafer, the wafer is transported to a polishing stage by a transport device, and then the wafer is suctioned and fixed onto the polishing stage. Then, the wafer on the polishing stage is pressed against the rotating polishing drum, and the outer edge of the wafer is polished by the polishing drum. If there is a misalignment between the center of the polishing stage and the center of the wafer, it will be difficult to apply the polishing drum evenly to the outer edge of the wafer, which may reduce the polishing quality of the wafer. There is. Therefore, there is a need to improve the accuracy in transporting the wafer to the polishing stage so that the center of the polishing stage and the center of the wafer are brought closer to each other.

An object of the present invention is to improve the accuracy of wafer transfer to a polishing stage.

A wafer transport device according to one embodiment is a wafer transport device that transports the wafer to a polishing stage that polishes the outer edge of the wafer, the wafer transport device is attached to a first guide rail extending in a first direction, and the first actuator drives the first a second slider attached to a second guide rail provided on the first slider and driven in a second direction intersecting the first direction by a second actuator; A transport hand that is attached to a second slider and grips the wafer to be transported to the polishing stage, and the first actuator is controlled to move the transport hand in the first direction by a target distance, and the wafer is a control system that transports the wafer to the polishing stage; and a measuring device that is communicatively connected to the control system and measures outer edge data of the wafer that has been transported to the polishing stage. The control system calculates the wafer center, which is the center position of the wafer, based on the outer edge data, and calculates the amount of eccentricity of the wafer center with respect to the stage center, which is the center position of the polishing stage. , the second actuator is controlled based on the amount of eccentricity to move the transfer hand in the second direction, and the target distance during wafer transfer is corrected based on the amount of eccentricity.

According to one aspect of the present invention, the control system controls the second actuator to move the transfer hand in the second direction based on the amount of eccentricity when the amount of eccentricity exceeds a threshold value, and transfers the wafer based on the amount of eccentricity. Correct the target distance at the time. Thereby, the accuracy of wafer transport can be improved.

FIG. 2 is a diagram showing part of a wafer manufacturing line. It is a figure showing a conveyance device and a polishing device of a 1st polishing process. It is a figure showing a part of a conveyance device and a polishing device of a 1st polishing process. FIG. 3 is a diagram showing the internal structure of a stage unit that constitutes the polishing apparatus. (A) is a diagram showing the transport unit from the direction of arrow 5A in FIG. 2, and (B) is a diagram showing the transport unit from the direction of arrow 5B in FIG. 2. (A) to (C) are diagrams showing the state of wafer transport. (A) and (B) are diagrams showing a measurement unit. FIG. 1 is a diagram showing an example of a control system. FIG. 3 is a diagram showing a polishing stage and a wafer. 7 is a flowchart illustrating an example of an execution procedure of conveyance position correction control. It is a figure showing a conveyance device and a polishing device during conveyance position correction control. (A) and (B) are diagrams showing a polishing stage unit and a measurement unit during conveyance position correction control. It is a figure showing an example of the displacement of the outer edge measured by a laser displacement meter. (A) and (B) are diagrams showing the position of the wafer center with respect to the stage center.

Hereinafter, embodiments of the present invention will be described in detail based on the drawings. In the following description, the same or substantially the same configurations and elements will be designated by the same reference numerals and repeated description will be omitted.

[Wafer production line]
FIG. 1 is a diagram showing a part of a wafer manufacturing line 10 for processing wafers such as silicon wafers. By using the illustrated wafer manufacturing line 10, polishing processing and the like are performed on wafers that are materials for semiconductor devices. As shown in FIG. 1, the wafer manufacturing line 10 is provided with a first notch process Pn1 and a second notch process Pn2 for forming a notch in the wafer, and a first polishing process Pp1 and a second notch process Pn2 for polishing the outer edge of the wafer. 2 polishing process Pp2 is provided.

The first notch process Pn1 is provided with a polishing device 13 that includes a polishing stage unit 11 that fixes the wafer, and a polishing machine 12 that polishes a notch on the wafer. Further, the first notch process Pn1 is provided with a transport device 15 that transports the wafer from the cassette 14 to the polishing stage unit 11, as shown by arrow a1. Similarly, the second notch process Pn2 is provided with a polishing device 18 that includes a polishing stage unit 16 that fixes the wafer and a polishing machine 17 that polishes a notch on the wafer. Further, the second notch process Pn2 is provided with a transport device 19 that transports the wafer from the polishing stage unit 11 of the previous process to the polishing stage unit 16, as shown by arrow a2.

The first polishing step Pp1 is provided with a polishing device 22 that includes a polishing stage unit 20 that fixes the wafer and a polishing machine 21 that polishes the outer edge of the wafer. Further, in the first polishing step Pp1, as shown by arrow a3, a transport device 23 is provided that transports the wafer from the polishing stage unit 16 of the previous step to the polishing stage unit 20. Similarly, the second polishing step Pp2 is provided with a polishing device 26 that includes a polishing stage unit 24 that fixes the wafer and a polishing machine 25 that polishes the outer edge of the wafer. Further, the second polishing step Pp2 is provided with a transport device 27 that transports the wafer from the polishing stage unit 20 of the previous step to the polishing stage unit 24, as shown by arrow a4.

Note that the transport hand 28 provided in the transport device 27 of the second polishing step Pp2 has a function of turning the wafer upside down. That is, in the first polishing process Pp1, the outer edge of the wafer is polished from the front side, whereas in the second polishing process Pp2, the outer edge of the wafer is polished from the back side. Furthermore, in the first and second polishing steps Pp1 and Pp2, the outer edge of the wafer may be simultaneously polished from both the front side and the back side. In this case, the wafer reversing mechanism is omitted from the transfer hand 28 of the transfer device 27. Furthermore, the process of polishing the outer edge of the wafer is not limited to the two polishing processes Pp1 and Pp2, and the outer edge of the wafer may be polished by one polishing process, or the outer edge of the wafer can be polished by three or more polishing processes. The outer edge may be polished.

As described above, the illustrated wafer manufacturing line 10 is provided with four transport devices 15, 19, 23, and 27. Among these transport devices 15, 19, 23, and 27, transport devices 23 and 27 provided in polishing steps Pp1 and Pp2 are wafer transport devices that are an embodiment of the present invention. Note that the transport devices 23 and 27 have similar configurations, so in the following explanation, the transport device 23 of the first polishing step Pp1 will be described, and the transport device 27 of the second polishing step Pp2 will be explained. Omitted.

[First polishing step]
FIG. 2 is a diagram showing the transport device 23 and polishing device 22 in the first polishing step Pp1, and FIG. 3 is a diagram showing a part of the transport device 23 and polishing device 22 in the first polishing step Pp1. Note that the X direction indicated by an arrow X in each drawing is a direction along a guide rail 72, which will be described later. Further, the Z direction indicated by arrow Z is a direction orthogonal to the X direction, and the Y direction indicated by arrow Y is a direction orthogonal to both the X direction and the Z direction.

As shown in FIGS. 2 and 3, a polishing device 22 including a polishing stage unit 20 (hereinafter referred to as stage unit 20) and a polishing machine 21 is provided in the first polishing step Pp1. The stage unit 20 is provided with a polishing stage 30 for fixing the wafer W, and the polishing machine 21 is provided with a polishing drum 31 for polishing the outer edge E of the wafer W. Further, the first polishing step Pp1 is provided with a transport device 23 including a transport unit 33 and a measuring unit 35. The transport unit 33 is provided with a transport hand 32 that grips the wafer W, and the measurement unit 35 is provided with a laser displacement meter 34 that measures the outer edge data of the wafer W.

[Polishing equipment]
FIG. 4 is a diagram showing the internal structure of the stage unit 20 that constitutes the polishing device 22. As shown in FIG. As shown in FIG. 4, the stage unit 20 includes a base frame 40 equipped with a stage lift motor 39, a lift section 42 equipped with a stage rotation motor 41, and a polishing stage 30 rotatably attached to the lift section 42. It has . Further, a hollow shaft 44 provided with a driven gear 43 is connected to the polishing stage 30 . Furthermore, a speed reduction mechanism 45 is connected to the stage rotation motor 41, and this speed reduction mechanism 45 is provided with a drive gear 46 that meshes with a driven gear 43. That is, the polishing stage 30 and the stage rotation motor 41 are connected to each other, and the polishing stage 30 can be rotated by the stage rotation motor 41. Further, the elevating section 42 is provided with a support plate 48 that includes a sleeve 47 that rotatably supports the hollow shaft 44 . This support plate 48 is provided with a bearing portion 50 via a connecting rod 49, and the bearing portion 50 is provided with a hollow threaded shaft 51 extending in the Z direction.

A nut 52 that engages with a screw shaft 51 is rotatably provided on the base frame 40 of the stage unit 20. Note that a steel ball (not shown) is inserted between the screw shaft 51 and the nut 52, and the screw shaft 51 and the nut 52 form a ball screw. A driven gear 53 is fixed to a nut 52 that is rotatably provided with respect to the base frame 40, and a drive gear 54 that meshes with the driven gear 53 is provided on the stage elevation motor 39. By rotating the stage elevating motor 39, the nut 52 of the base frame 40 can be rotated, and the screw shaft 51 of the elevating section 42 can be moved up and down in the Z direction. That is, by rotating the stage elevating motor 39, the elevating section 42 and the polishing stage 30 supported thereby can be moved up and down in the Z direction.

Further, a through passage 55 is formed in the polishing stage 30 and the hollow shaft 44, and a negative pressure pipe 56 is connected to this through passage 55. A negative pressure chamber 58 is connected to the negative pressure pipe 56 via an electromagnetic valve 57, and a negative pressure pump 59 is connected to the negative pressure chamber 58. The electromagnetic valve 57 is operable in an adsorption state in which the through passage 55 and the negative pressure chamber 58 are connected to each other, and in an open state in which the through passage 55 is connected to the atmosphere release port 60. By controlling the electromagnetic valve 57 to be in the suction state, the through flow path 55 and the negative pressure chamber 58 can be connected, and the pressure inside the through flow path 55 is reduced to attract the wafer W onto the polishing stage 30. be able to. On the other hand, by controlling the electromagnetic valve 57 to the open state, the through flow path 55 and the atmosphere release port 60 can be connected, and the pressure inside the through flow path 55 can be increased to release the adsorption of the wafer W. Can be done.

As shown in FIG. 2, the polishing apparatus 22 includes a polishing machine 21 that polishes the outer edge E of the circular wafer W. The polishing machine 21 is provided with a polishing drum 31 disposed above a polishing stage 30, and is also provided with a drum rotation motor 62 connected to the polishing drum 31 via a belt mechanism 61. When polishing the outer edge E of the wafer W placed on the polishing stage 30, the polishing drum 31 is rotated by the drum rotation motor 62, and the polishing stage 30 is raised in the Z direction to a predetermined position. Thereby, the outer edge E of the wafer W can be brought into contact with the polishing pad 31a provided on the polishing drum 31, and the outer edge E of the wafer W can be polished by the polishing drum 31. Note that when polishing the wafer W using the polishing drum 31, in order to uniformly polish the outer edge E of the wafer W, the stage rotation motor 41 is driven to rotate the polishing stage 30, that is, the wafer W. Further, the rotation center of the polishing stage 30 and the rotation center of the polishing drum 31 coincide with each other.

[Transport device]
5A is a diagram showing the transport unit 33 from the direction of arrow 5A in FIG. 2, and FIG. 5B is a diagram showing the transport unit 33 from the direction of arrow 5B in FIG. Note that FIGS. 5A and 5B show partial cross-sectional views of the transport unit 33 in order to show the internal structure of the transport unit 33.

As shown in FIGS. 2 and 5, the pedestal 70 is provided with a guide rail (first guide rail) 72 extending in the X direction (first direction), and a first slider 71 is movable on the guide rail 72. is attached to. Further, the pedestal 70 is provided with a screw shaft 73 extending in the X direction, and the first slider 71 is provided with a nut 74 that engages with the screw shaft 73. Note that a steel ball (not shown) is inserted between the screw shaft 73 and the nut 74, and the screw shaft 73 and the nut 74 form a ball screw. Further, the first slider 71 is provided with a conveyance motor (first actuator) 75 that is an electric motor for driving a nut. The nut 74 and the conveyance motor 75 are connected to each other via a belt mechanism 76. By driving the transport motor 75 and rotating the nut 74, the first slider 71 can be moved along the screw shaft 73 and the guide rail 72. That is, the transport unit 33 is provided with the first slider 71 that is driven in the X direction by the transport motor 75.

Further, the first slider 71 is provided with a guide rail (second guide rail) 81 extending in the Y direction (second direction), and a second slider 82 is movably attached to the guide rail 81. Furthermore, as shown in FIG. 5(A), the first slider 71 is provided with an adjustment actuator (second actuator) 83 equipped with a telescoping rod. A second slider 82 is connected thereto. The illustrated adjustment actuator 83 is an electric actuator that extends and contracts the telescopic rod 83a using an electric motor (not illustrated). By expanding and contracting the telescopic rod 83a of the adjustment actuator 83, the second slider 82 can be moved along the guide rail 81. That is, the transport unit 33 is provided with the second slider 82 that is driven in the Y direction by the adjustment actuator 83.

Further, the second slider 82 is provided with a lifting rod 85 extending in the Z direction. A lifting actuator 86 including a telescopic rod 86a is connected to the upper end of the lifting rod 85 via an adapter 87. The illustrated lifting actuator 86 is an electric actuator that extends and contracts a telescoping rod 86a using an electric motor 88. Further, a transport hand 32 that grips the wafer W is connected to the lower end of the lifting rod 85. The transfer hand 32 has a first arm section 89 and a second arm section 90 that grip the wafer W. Note that it is possible to move the first arm section 89 in the Y direction, and it is possible to move the second arm section 90 in the Y direction using an actuator (not shown). In this way, the transport unit 33 is provided with the transport hand 32 attached to the second slider 82.

By using such a transport unit 33, it is possible to transport the wafer W to the polishing stage 30. Here, FIGS. 6A to 6C are diagrams showing the transportation status of the wafer W. 6(A), FIG. 6(B), and FIG. 6(C) show a situation in which the wafer W is transported toward the polishing stage 30 in this order.

As shown in FIG. 6A, when the wafer W on the polishing stage unit 16 (not shown) is held by the transport hand 32, the transport motor 75 and the lifting actuator 86 are controlled, and the transport hand moves as shown by arrow b1. 32 moves toward the polishing stage 30. That is, as shown by arrow D1 in FIG. 1, by controlling the transport motor 75 at a predetermined target rotation angle, the transport hand 32 is moved in the X direction by a predetermined target movement distance (target distance) D1.

Subsequently, as shown by the arrow b2 in FIG. 6(B), when the wafer W is transported to the polishing stage 30, the first arm part 89 and the second arm part 90 move as shown by the arrow b3, The wafer W is released from the transfer hand 32. Note that in FIG. 6B, since negative pressure is supplied to the through flow path 55 of the polishing stage 30, the wafer W is suctioned and fixed onto the polishing stage 30. Then, when the first arm section 89 and the second arm section 90 separate from the wafer W on the polishing stage 30, the transport motor 75 and the lifting actuator 86 are controlled as shown by the arrow b4 in FIG. The hand 32 moves toward a predetermined standby position.

As described above, the transfer device 23 is provided with the measurement unit 35 that measures the outer edge data of the wafer W. Here, FIGS. 7A and 7B are diagrams showing the measurement unit 35. Note that FIGS. 7A and 7B show partial cross-sectional views of the measurement unit 35 in order to show the internal structure of the measurement unit 35.

As shown in FIG. 7(A), the measurement unit 35 includes a base plate 95 to which a storage case 93 and an air cylinder 94 are attached, and a lift table 96 connected to a telescopic rod 94a of the air cylinder 94. have. The lifting table 96 is provided with an installation base 97 on which the laser displacement meter (measuring device) 34 is installed, and a waterproof cover 98 that covers the laser displacement meter 34. Further, in order to drive the air cylinder 94 connected to the lifting table 96, two supply/discharge pipes 99 and 100 are connected to the air cylinder 94. An air chamber 102 is connected to these supply/discharge pipes 99, 100 via a solenoid valve 101, and an air pump 103 is connected to the air chamber 102.

The electromagnetic valve 101 is operable in a lowering state in which the elevating table 96 is lowered and in an ascending state in which the elevating table 96 is raised. By controlling the electromagnetic valve 101 to the lowered state, the supply/discharge pipe 99 and the air chamber 102 are connected to each other, and the supply/discharge pipe 100 and the exhaust port 104 are connected to each other. Thereby, as shown in FIG. 7A, the telescopic rod 94a of the air cylinder 94 can be retracted, and the lifting table 96 can be lowered so that the laser displacement meter 34 is accommodated in the accommodation case 93. On the other hand, by controlling the electromagnetic valve 101 to rise, the supply/discharge pipe 99 and the exhaust port 105 are connected to each other, and the supply/discharge pipe 100 and the air chamber 102 are connected to each other. As a result, as shown in FIG. 7B, the telescopic rod 94a of the air cylinder 94 can be extended, and the lifting table 96 can be raised so that the laser displacement meter 34 comes out from the storage case 93.

In this way, the laser displacement meter 34 provided in the measurement unit 35 is movable between the storage position where it is stored in the storage case 93 and the measurement position where it is taken out from the storage case 93. As shown in FIG. 7B, by moving the laser displacement meter 34 to the measurement position, the laser displacement meter 34 is placed radially outward of the wafer W on the polishing stage 30. Thereby, it is possible to irradiate laser light toward the outer edge E of the wafer W from the laser displacement meter 34, and it is possible to measure the position of the outer edge E of the wafer W by the laser displacement meter 34. Further, the laser displacement meter 34 is communicably connected to a control unit 116 that constitutes a control system 120, which will be described later.

[Control system]
As shown in FIG. 1, the wafer manufacturing line 10 is provided with a plurality of control units 110 to 118 to control polishing devices 13, 18, 22, 26, transport devices 15, 19, 23, 27, etc. There is. As control units for the wafer manufacturing line 10, there are control units 110 to 113 that control each polishing device 13, 18, 22, and 26, and control units 114 to 117 that control each transfer device 15, 19, 23, and 27. . Further, as a control unit of the wafer manufacturing line 10, a main control unit 118 is provided which integrally controls these control units. Note that the control units 110 to 118 are communicably connected to each other via a wired or wireless communication network 119. Furthermore, each of the control units 110 to 118 provided in the wafer manufacturing line 10 has a microcontroller incorporating a processor, main memory, and the like. A predetermined program is stored in the main memory, and the instruction set of the program is executed by the processor. Furthermore, the control units 110 to 118 are provided with an input circuit, a drive circuit, an external memory, and the like.

Further, in order to control the wafer transfer device 23, which is an embodiment of the present invention, a control system 120 is configured by two control units 112 and 116. Here, FIG. 8 is a diagram showing an example of the control system 120. As shown in FIG. 8, the control system 120 includes a control unit 112 that controls the polishing device 22 and a control unit 116 that controls the transport device 23. The control unit 112 can control the stage rotation motor 41, the stage elevation motor 39, the electromagnetic valve 57, the drum rotation motor 62, and the like. Further, the control unit 116 can control the transport motor 75, the adjustment actuator 83, the elevation actuator 86, the first arm section 89, the second arm section 90, the laser displacement meter 34, the electromagnetic valve, and the like.

[Transportation position correction control]
FIG. 9 is a diagram showing the polishing stage 30 and the wafer W. As described above, in the first polishing step Pp1, the wafer W is transported onto the polishing stage 30, and the outer edge E of the wafer W is polished by the polishing drum 31. Here, as shown in the enlarged part of FIG. 9, if the wafer center Cw, which is the center position of the wafer W, is deviated from the stage center Cs, which is the center position of the polishing stage 30, the outer edge E of the wafer W is Difficult to polish uniformly. Therefore, the control system 120 executes transport position correction control to correct the transport position of the wafer W by the transport unit 33 when the wafer center Cw is deviated from the stage center Cs.

FIG. 10 is a flowchart illustrating an example of the procedure for carrying out the conveyance position correction control. FIG. 11 is a diagram showing the transport device 23 and polishing device 22 under transport position correction control, and FIGS. 12(A) and 12(B) are diagrams showing the stage unit 20 and measurement unit 35 under transport position correction control. It is. Note that FIG. 12A shows a plan view of the stage unit 20 as well as a plan view of the measurement unit 35 with the waterproof cover 98 removed. Further, FIG. 12(B) shows a side view of the stage unit 20 as well as a side view of the measurement unit 35 to which the waterproof cover 98 is attached.

As shown in FIG. 10, in step S10, it is determined whether the wafer W has been transported to the polishing stage 30 by the transport unit 33. When it is determined in step S10 that the wafer W has been transferred to the polishing stage 30, the process proceeds to step S11, where a process of counting the number of transfers C1 is executed, and the process proceeds to step S12, where it is determined whether or not the number of transfers C1 exceeds a predetermined number of times X1. is determined. In step S12, if it is determined that the number of times of conveyance C1 exceeds the predetermined number of times let That is, as shown in FIGS. 11 and 12, by raising the elevating table 96 of the measurement unit 35, the laser displacement meter 34 moves out of the storage case 93 and moves to the measurement position located radially outward of the wafer W. do. Note that the arrow r1 shown in FIG. 12 indicates the radial direction of the wafer W.

When the laser displacement meter 34 is moved to the measurement position in this way, the process proceeds to step S15, and while the polishing stage 30 is rotated 360 degrees, the position of the outer edge E of the wafer W (outer edge data) is measured by the laser displacement meter 34. Ru. That is, as shown in FIG. 12(A), the polishing stage 30, that is, the wafer W, is rotated in the direction of arrow r2 using the stage rotation motor 41. Further, as shown by a dashed line L in FIG. 12A, a laser beam is irradiated from the laser displacement meter 34 toward the outer edge E, and the laser beam reflected from the outer edge E is taken into the laser displacement meter 34. Thereby, as shown in the enlarged part of FIG. 12(A), the positions of the plurality of measurement points Pm set on the outer edge E of the wafer are measured by the laser displacement meter 34.

Here, FIG. 13 is a diagram showing an example of the displacement of the outer edge E measured by the laser displacement meter 34. When the wafer center Cw deviates from the stage center Cs, the laser displacement meter 34 detects the position, that is, the displacement, of the outer edge E, which changes depending on the rotation angle of the polishing stage 30, as shown in FIG. Note that the laser displacement meter 34 may measure the position of the outer edge E at every predetermined rotation angle, or may measure the position of the outer edge E continuously. That is, the measurement points Pm set on the wafer outer edge E may be set at predetermined intervals in the circumferential direction, or may be set continuously in the circumferential direction. As shown in FIG. 10, when the position of the outer edge E of the wafer is measured by the laser displacement meter 34 in step S15, the process proceeds to step S16, and the laser displacement meter 34 is moved by lowering the lifting table 96 of the measurement unit 35. It is moved to the storage position within the storage case 93.

Next, in step S17, based on the position of the wafer outer edge E measured by the laser displacement meter 34, the center coordinates (Xa, Ya) of the wafer W are calculated when the center coordinates of the polishing stage 30 are set as the origin. That is, the contour data of the wafer W is generated from the position data of the wafer outer edge E, and the center coordinates (Xa, Ya) of the wafer W are calculated from the contour data of the wafer W. Further, in step S17, as shown in FIG. 9, the distance α between the stage center Cs and the wafer center Cw, that is, the eccentricity α of the wafer center Cw with respect to the stage center Cs is calculated. In other words, the eccentricity α of the wafer center Cw with respect to the stage center Cs is the distance in the XY plane between the center axis passing through the stage center Cs and the center axis passing through the wafer center Cw. Moreover, the XY plane is a plane orthogonal to the Z direction.

In the following step S18, it is determined whether the eccentricity amount α exceeds a predetermined threshold value X2. If it is determined in step S18 that the amount of eccentricity α exceeds the threshold value X2, the process proceeds to step S19, and the adjustment actuator 83 of the transport unit 33 is controlled so that the wafer center Cw approaches the stage center Cs. That is, the adjustment actuator 83 moves the second slider 82 by a predetermined distance in the Y direction so that the Y coordinate of the wafer center Cw becomes "0". Subsequently, in step S20, the target moving distance D1 of the first slider 71 used during wafer transport is corrected so that the wafer center Cw coincides with the stage center Cs. That is, the target moving distance D1 of the first slider 71 by the transport motor 75 is corrected so that the X coordinate of the wafer center Cw becomes "0".

Note that if it is determined in step S10 that the wafer W has not been transferred to the polishing stage 30, or if it is determined in step S12 that the number of transfers C1 is less than or equal to the predetermined number of times X1, the adjustment actuator 83 is The routine exits without performing any control or correction of the target moving distance D1. If it is determined in step S18 that the amount of eccentricity α is less than or equal to the threshold value X2, the routine exits without controlling the adjustment actuator 83 or correcting the target movement distance D1.

Here, FIGS. 14A and 14B are diagrams showing the position of the wafer center Cw with respect to the stage center Cs. FIG. 14(A) shows the situation before the transport position is corrected, and FIG. 14(B) shows the situation after the transport position is corrected. As shown in FIG. 14A, when the eccentricity α of the wafer center Cw with respect to the stage center Cs exceeds the threshold value X2, the coordinates (Xa, Ya) of the wafer center Cw with respect to the stage center Cs are calculated. Then, the adjustment actuator 83 moves the second slider 82 by a predetermined distance in the Y direction so that the Y coordinate of the wafer center Cw becomes "0". Further, the target moving distance D1 of the first slider 71 by the transport motor 75 is corrected so that the X coordinate of the wafer center Cw becomes "0".

Thereby, as shown in FIG. 14B, the wafer W can be transported using the transport unit 33 so that the wafer center Cw is aligned with the stage center Cs during the next transport. That is, the accuracy of transporting the wafer W to the polishing stage 30 can be improved, and the centers of the polishing stage 30 and the wafer W can be made to coincide with each other, so that the polishing accuracy of the outer edge E of the wafer W can be improved. Furthermore, since the eccentricity α of the wafer center Cw with respect to the stage center Cs is periodically determined in the wafer manufacturing line 10, polishing defects due to misalignment of the wafer W can be significantly reduced.

Further, by measuring the outer edge data of the wafer W with the laser displacement meter 34, the outer edge data can be measured without touching the wafer W. Thereby, outer edge data can be acquired without impairing the quality of the wafer W. Furthermore, the laser displacement meter 34, which is a measuring device, is movable between a storage position where it is housed in the housing case 93 and a measurement position where it is taken out from the housing case 93. As a result, when the wafer W is polished by the polishing drum 31, the laser displacement meter 34 can be moved to the storage position, so the laser displacement meter 34 can be appropriately protected from the polishing liquid that is scattered during the polishing process. .

It goes without saying that the present invention is not limited to the embodiments described above, and can be modified in various ways without departing from the spirit thereof. For example, in the above description, the control system 120 is configured by two control units 112 and 116, but the control system 120 is not limited to this, and the control system 120 may be configured by one control unit, or three control units. The control system 120 may be configured by the above control units. Further, in the illustrated example, the X direction in which the first slider 71 moves and the Y direction in which the second slider 82 moves are orthogonal to each other, but the invention is not limited to this, and the X direction and the Y direction are It is fine as long as they intersect with each other. For example, the angle between the X direction and the Y direction may be less than 90°, or the angle between the X direction and the Y direction may be greater than 90°. Further, a servo motor can be used as the transport motor 75 that drives the first slider 71, and a servo motor can be used as the electric motor incorporated in the adjustment actuator 83 that drives the second slider 82.

In the above description, the laser displacement meter 34 using a laser beam is used as the measurement device, but the measurement device is not limited to this, and any device can be used as long as it can acquire data on the outer edge of the wafer W without contact. Also good. For example, as the measuring device, an ultrasonic displacement meter, a capacitance displacement meter, or an eddy current displacement meter may be used. Furthermore, for example, an imaging camera that captures an image of the outline of the outer edge E of the wafer may be used as the measuring device. Even when an imaging camera is used as the measuring device, the contour data of the wafer W can be detected as the outer edge data of the wafer W, and the wafer center Cw can be calculated from the contour data of the wafer W. Furthermore, in the above description, the wafer W has a notch formed therein, but the present invention is not limited to this, and the wafer W may also have an orientation flat formed therein.

23 Transport device (wafer transport device)
27 Transfer device (wafer transfer device)
28 Transfer hand 30 Polishing stage 32 Transfer hand 34 Laser displacement meter (measuring device)
71 First slider 72 Guide rail (first guide rail)
75 Transport motor (first actuator)
81 Guide rail (second guide rail)
82 Second slider 83 Adjustment actuator (second actuator)
93 Containment case (case)
120 Control system W Wafer E Outer edge X X direction (first direction)
Y Y direction (second direction)
D1 Target movement distance (target distance)
Cw Wafer center Cs Stage center α Eccentricity X2 Threshold

Claims (4)

A wafer transport device that transports the wafer to a polishing stage that polishes the outer edge of the wafer,
a first slider attached to a first guide rail extending in a first direction and driven in the first direction by a first actuator;
a second slider attached to a second guide rail provided on the first slider and driven by a second actuator in a second direction intersecting the first direction;
a transport hand attached to the second slider and gripping the wafer being transported to the polishing stage;
a control system that controls the first actuator to move the transfer hand in the first direction by a target distance to transfer the wafer to the polishing stage;
a measurement device communicatively connected to the control system and measuring outer edge data of the wafer transferred to the polishing stage;
has
The control system calculates a wafer center, which is a center position of the wafer, based on the outer edge data, and calculates an eccentricity of the wafer center with respect to a stage center, which is a center position of the polishing stage.
The control system controls the second actuator based on the eccentricity to move the transfer hand in the second direction when the eccentricity exceeds a threshold, and controls the transfer hand during wafer transfer based on the eccentricity. correcting the target distance;
Wafer transport equipment. The wafer transport device according to claim 1,
The measuring device measures the positions of a plurality of measurement points set on the outer edge of the wafer as the outer edge data.
Wafer transport equipment. The wafer transport device according to claim 2,
The measurement device measures the position of the measurement point while the polishing stage is rotated.
Wafer transport equipment. The wafer transport device according to any one of claims 1 to 3,
The measurement device is movable between a storage position where it is housed in a case and a measurement position where it comes out of the case and measures the outer edge data.
Wafer transport equipment.

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