Wafer transport equipment

Abstract

To improve the accuracy of wafer transfer to a polishing stage.SOLUTION: 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 transfer device has a transfer hand that is attached to the second slider and grips a wafer to be transferred to a polishing stage. The wafer transfer device includes a control system that moves the transfer hand by a target distance in the first direction by controlling the first actuator, and transfers the wafer to the polishing stage. The wafer transfer device includes a measuring instrument that is communicatively connected to the control system and measures outer edge data of the wafer transferred to the polishing stage.SELECTED DRAWING: Figure 10

Description

Technical Field

[0001] The present invention relates to a wafer transfer device for transferring a wafer to a polishing stage.

Background Art

[0002] In the manufacturing process of semiconductor devices, electronic circuits are formed on wafers such as silicon wafers. The wafers made of this semiconductor material are not only subjected to a polishing process for polishing the surface of the wafer, but also subjected to a polishing process for polishing the outer edge of the wafer from the viewpoint of preventing chipping associated with handling (see Patent Document 1).

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] By the way, when polishing the outer edge of a wafer, after the wafer is transferred to the polishing stage by a transfer device, the wafer is adsorbed and fixed on the polishing stage. Then, the wafer on the polishing stage is pressed against a rotating polishing drum, and the outer edge of the wafer is polished by the polishing drum. Here, if there is a deviation between the center of the polishing stage and the center of the wafer, it becomes difficult to uniformly apply the polishing drum to the outer edge of the wafer, and there is a risk of deteriorating the polishing quality of the wafer. Therefore, it is required to improve the accuracy when transferring the wafer to the polishing stage so that the centers of the polishing stage and the wafer approach each other.

[0005] An object of the present invention is to improve the transfer accuracy of a wafer to a polishing stage.

Means for Solving the Problems

[0006] A wafer transfer apparatus according to one embodiment is a wafer transfer apparatus for transferring a wafer to a polishing stage for polishing the outer edge of the wafer, comprising: 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 in a second direction intersecting the first direction by a second actuator; a transfer hand attached to the second slider for gripping the wafer being transferred to the polishing stage; a control system that controls the first actuator to move the transfer hand by a target distance in the first direction and transfer the wafer to the polishing stage; and a device that is communicably connected to the control system and measures the outer edge data of the wafer transferred to the polishing stage. Laser displacement sensor and, have The laser displacement meter, positioned radially outward from the wafer, measures the outer edge data, which is the positions of multiple measurement points on the outer edge of the wafer, while the polishing stage is rotating. The control system calculates the wafer center, which is the central position of the wafer, based on the outer edge data, and calculates the eccentricity of the wafer center with respect to the stage center, which is the central position of the polishing stage. do. The control system, when the eccentricity exceeds a threshold, controls the second actuator based on the eccentricity to move the transport hand in the second direction, and corrects the target distance during wafer transport based on the eccentricity. Another embodiment of the wafer transport apparatus is a wafer transport apparatus for transporting a wafer to a polishing stage for polishing the outer edge of the wafer, and includes: 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 in a second direction intersecting the first direction by a second actuator; a transport hand attached to the second slider for gripping the wafer to be transported to the polishing stage; a control system that controls the first actuator to move the transport hand by a target distance in the first direction and transport the wafer to the polishing stage; and a measuring instrument that is communicatively connected to the control system and measures the outer edge data of the wafer transported to the polishing stage. The measuring instrument is movable between a storage position where it is housed in a case and a measuring position where it is outside the case and measures the outer edge data. The control system calculates the wafer center, which is the center position of the wafer, based on the outer edge data, and calculates the eccentricity of the wafer center with respect to the stage center, which is the center position of the polishing stage. The control system, when the eccentricity exceeds a threshold, controls the second actuator based on the eccentricity to move the transport hand in the second direction, and corrects the target distance during wafer transport based on the eccentricity. [Effects of the Invention]

[0007] According to one aspect of the present invention, when the eccentricity exceeds a threshold, the control system controls the second actuator based on the eccentricity to move the transport hand in a second direction, and corrects the target distance during wafer transport based on the eccentricity. This improves the accuracy of wafer transport. [Brief explanation of the drawing]

[0008] [Figure 1] This diagram shows a portion of the wafer manufacturing line. [Figure 2] This diagram shows the conveying device and polishing device for the first polishing process. [Figure 3]This diagram shows a portion of the conveying and polishing equipment used in the first polishing process. [Figure 4] This diagram shows the internal structure of the stage unit that makes up the polishing apparatus. [Figure 5] (A) is a diagram showing the transport unit from the direction of arrow 5A in Figure 2, and (B) is a diagram showing the transport unit from the direction of arrow 5B in Figure 2. [Figure 6] Figures (A) to (C) show the wafer transport process. [Figure 7] (A) and (B) are diagrams showing the measurement unit. [Figure 8] This diagram shows an example of a control system. [Figure 9] This diagram shows the polishing stage and wafer. [Figure 10] This flowchart shows an example of the procedure for performing transport position correction control. [Figure 11] This diagram shows the conveying device and polishing device during conveying position correction control. [Figure 12] Figures (A) and (B) show the polishing stage unit and the measuring unit during transport position correction control. [Figure 13] This figure shows an example of outer edge displacement measured by a laser displacement sensor. [Figure 14] (A) and (B) are diagrams showing the position of the wafer center relative to the stage center. [Modes for carrying out the invention]

[0009] Embodiments of the present invention will be described in detail below with reference to the drawings. In the following description, identical or substantially identical components and elements will be denoted by the same reference numerals, and repeated descriptions will be omitted.

[0010] [Wafer manufacturing 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 and other processes are performed on the 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 notches in the wafers, and a first polishing process Pp1 and a second polishing process Pp2 for polishing the outer edges of the wafers.

[0011] The first notch process Pn1 is provided with a polishing apparatus 13 including a polishing stage unit 11 for fixing the wafer and a polishing machine 12 for polishing the notch in the wafer. Also, in the first notch process Pn1, as shown by an arrow a1, a transfer device 15 for transferring the wafer from a cassette 14 to the polishing stage unit 11 is provided. Similarly, the second notch process Pn2 is provided with a polishing apparatus 18 including a polishing stage unit 16 for fixing the wafer and a polishing machine 17 for polishing the notch in the wafer. Also, in the second notch process Pn2, as shown by an arrow a2, a transfer device 19 for transferring the wafer from the polishing stage unit 11 of the previous process to the polishing stage unit 16 is provided.

[0012] The first polishing process Pp1 is provided with a polishing apparatus 22 including a polishing stage unit 20 for fixing the wafer and a polishing machine 21 for polishing the outer edge of the wafer. Also, in the first polishing process Pp1, as shown by an arrow a3, a transfer device 23 for transferring the wafer from the polishing stage unit 16 of the previous process to the polishing stage unit 20 is provided. Similarly, the second polishing process Pp2 is provided with a polishing apparatus 26 including a polishing stage unit 24 for fixing the wafer and a polishing machine 25 for polishing the outer edge of the wafer. Also, in the second polishing process Pp2, as shown by an arrow a4, a transfer device 27 for transferring the wafer from the polishing stage unit 20 of the previous process to the polishing stage unit 24 is provided.

[0013] Note that the transfer hand 28 provided in the transfer device 27 of the second polishing step Pp2 has a function of inverting the front and back of the wafer. That is, in the first polishing step Pp1, the outer edge is polished from the front surface side of the wafer, while in the second polishing step Pp2, the outer edge is polished from the back surface side of the wafer. Also, in the first and second polishing steps Pp1 and Pp2, the outer edge may be polished simultaneously from both the front surface side and the back surface side of the wafer. In this case, the wafer inversion mechanism from the transfer hand 28 of the transfer device 27 is reduced. Furthermore, the process of polishing the outer edge of the wafer is not limited to the two polishing steps Pp1 and Pp2, and the outer edge of the wafer may be polished by one polishing step, or may be polished by three or more polishing steps.

[0014] As described above, the illustrated wafer manufacturing line 10 is provided with four transfer devices 15, 19, 23, and 27. Among these transfer devices 15, 19, 23, and 27, the transfer devices 23 and 27 provided in the polishing steps Pp1 and Pp2 are wafer transfer devices according to an embodiment of the present invention. Since the transfer devices 23 and 27 have the same configuration as each other, in the following description, the transfer device 23 of the first polishing step Pp1 will be described, and the description of the transfer device 27 of the second polishing step Pp2 will be omitted.

[0015] [First Polishing Step] FIG. 2 is a diagram showing the transfer device 23 and the polishing device 22 of the first polishing step Pp1, and FIG. 3 is a diagram showing a part of the transfer device 23 and the polishing device 22 of the first polishing step Pp1. Note that the X direction indicated by the arrow X in each drawing is the direction along the guide rail 72 described later. Also, the Z direction indicated by the arrow Z is a direction orthogonal to the X direction, and the Y direction indicated by the arrow Y is a direction orthogonal to both the X direction and the Z direction.

[0016] As shown in Figures 2 and 3, the first polishing step Pp1 includes a polishing apparatus 22 consisting of a polishing stage unit 20 (hereinafter referred to as the stage unit 20) and a polishing machine 21. The stage unit 20 is equipped with a polishing stage 30 for fixing the wafer W, and the polishing machine 21 is equipped with a polishing drum 31 for polishing the outer edge E of the wafer W. The first polishing step Pp1 also includes a transport apparatus 23 consisting of a transport unit 33 and a measuring unit 35. The transport unit 33 is equipped with a transport hand 32 for gripping the wafer W, and the measuring unit 35 is equipped with a laser displacement meter 34 for measuring the outer edge data of the wafer W.

[0017] [Polishing equipment] Figure 4 shows the internal structure of the stage unit 20 that constitutes the polishing apparatus 22. As shown in Figure 4, the stage unit 20 has a base frame 40 equipped with a stage lifting motor 39, a lifting section 42 equipped with a stage rotating motor 41, and a polishing stage 30 that is rotatably mounted to the lifting section 42. A hollow shaft 44 equipped with a driven gear 43 is connected to the polishing stage 30. Furthermore, a reduction mechanism 45 is connected to the stage rotating motor 41, and this reduction mechanism 45 is provided with a drive gear 46 that meshes with the driven gear 43. In other words, the polishing stage 30 and the stage rotating motor 41 are connected to each other, and the polishing stage 30 can be rotated by the stage rotating motor 41. The lifting section 42 is also provided with a support plate 48 equipped with a sleeve 47 that rotatably supports the hollow shaft 44. A bearing section 50 is provided on this support plate 48 via a connecting rod 49, and a hollow screw shaft 51 extending in the Z direction is provided on the bearing section 50.

[0018] A nut 52 that engages with a screw shaft 51 is rotatably mounted on the base frame 40 of the stage unit 20. A steel ball (not shown) is inserted between the screw shaft 51 and the nut 52, forming a ball screw. A driven gear 53 is fixed to the nut 52, which is rotatably mounted on the base frame 40, and a drive gear 54 that meshes with the driven gear 53 is provided on the stage lifting motor 39. By rotating the stage lifting motor 39, the nut 52 on the base frame 40 can be rotated, and the screw shaft 51 of the lifting section 42 can be moved up and down in the Z direction. In other words, by rotating the stage lifting motor 39, the lifting section 42 and the polishing stage 30 supported by it can be moved up and down in the Z direction.

[0019] Furthermore, through-channels 55 are formed in the polishing stage 30 and the hollow shaft 44, and a negative pressure pipe 56 is connected to these through-channels 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 can operate in two states: an adsorption state, which connects the through-channel 55 and the negative pressure chamber 58 to each other, and an open state, which connects the through-channel 55 to the atmospheric outlet port 60. By controlling the electromagnetic valve 57 to the adsorption state, the through-channel 55 and the negative pressure chamber 58 can be connected, and the pressure in the through-channel 55 can be reduced to adsorb the wafer W onto the polishing stage 30. On the other hand, by controlling the electromagnetic valve 57 to the open state, the through-channel 55 and the atmospheric outlet port 60 can be connected, and the pressure in the through-channel 55 can be increased to release the adsorption of the wafer W.

[0020] As shown in Figure 2, the polishing apparatus 22 has a polishing machine 21 for polishing the outer edge E of a circular wafer W. The polishing machine 21 is equipped with a polishing drum 31 positioned above a polishing stage 30, and 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 drum rotation motor 62 rotates the polishing drum 31 and raises the polishing stage 30 to a predetermined position in the Z direction. This allows the outer edge E of the wafer W to come 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. When polishing the wafer W with the polishing drum 31, the stage rotation motor 41 is driven to rotate the polishing stage 30, i.e., the wafer W, in order to uniformly polish the outer edge E of the wafer W. The rotation centers of the polishing stage 30 and the polishing drum 31 coincide with each other.

[0021] [Conveying equipment] Figure 5(A) shows the transport unit 33 from the direction of arrow 5A in Figure 2, and Figure 5(B) shows the transport unit 33 from the direction of arrow 5B in Figure 2. Figures 5(A) and (B) also show partial cross-sectional views of the transport unit 33 to illustrate its internal structure.

[0022] As shown in Figures 2 and 5, the frame 70 is provided with a guide rail (first guide rail) 72 extending in the X direction (first direction), and a first slider 71 is movably attached to the guide rail 72. The frame 70 is also 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. A steel ball (not shown) is inserted between the screw shaft 73 and the nut 74, forming a ball screw. The first slider 71 is also provided with a transport motor (first actuator) 75, which is an electric motor for driving the nut. The nut 74 and the transport motor 75 are connected to each other via a belt mechanism 76. By driving the transport motor 75 to rotate the nut 74, the first slider 71 can be moved along the screw shaft 73 and the guide rail 72. In other words, the transport unit 33 is provided with a first slider 71 that is driven in the X direction by the transport motor 75.

[0023] Furthermore, the first slider 71 is provided with a guide rail (second guide rail) 81 extending in the Y direction (second direction), and the second slider 82 is movably attached to the guide rail 81. In addition, as shown in Figure 5(A), the first slider 71 is provided with an adjustment actuator (second actuator) 83 equipped with a telescopic rod, and the second slider 82 is connected to the telescopic rod 83a of the adjustment actuator 83 via a bracket 84. The adjustment actuator 83 shown is an electric actuator that extends and retracts the telescopic rod 83a using an electric motor (not shown). By extending and retracting the telescopic rod 83a of the adjustment actuator 83, the second slider 82 can be moved along the guide rail 81. In other words, the transport unit 33 is provided with a second slider 82 that is driven in the Y direction by the adjustment actuator 83.

[0024] Furthermore, the second slider 82 is provided with a lifting rod 85 extending in the Z direction. A lifting actuator 86 equipped with a telescopic rod 86a is connected to the upper end of the lifting rod 85 via an adapter 87. The lifting actuator 86 shown in the figure is an electric actuator that extends and retracts the telescopic rod 86a using an electric motor 88. In addition, a transport hand 32 for gripping wafers W is connected to the lower end of the lifting rod 85. The transport hand 32 has a first arm portion 89 and a second arm portion 90 for gripping wafers W. It is possible to move the first arm portion 89 in the Y direction and the second arm portion 90 in the Y direction using an actuator (not shown). Thus, the transport unit 33 is provided with a transport hand 32 attached to the second slider 82.

[0025] By using such a transport unit 33, it is possible to transport the wafer W to the polishing stage 30. Here, Figures 6(A) to 6(C) show the transport status of the wafer W. Figures 6(A), 6(B), and 6(C) show the situation in which the wafer W is transported toward the polishing stage 30.

[0026] As shown in Figure 6(A), 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 32 moves toward the polishing stage 30 as indicated by arrow b1. In other words, as indicated by arrow D1 in Figure 1, the transport motor 75 is controlled to a predetermined target rotation angle, thereby moving the transport hand 32 by a predetermined target travel distance (target distance) D1 in the X direction.

[0027] Next, as shown by arrow b2 in Figure 6(B), when the wafer W is transported to the polishing stage 30, the first arm 89 and the second arm 90 move, as shown by arrow b3, and the wafer W is released from the transport hand 32. In Figure 6(B), negative pressure is supplied to the through-flow channel 55 of the polishing stage 30, so the wafer W is held in place by suction on the polishing stage 30. Once the first arm 89 and the second arm 90 are released from the wafer W on the polishing stage 30, the transport motor 75 and the lifting actuator 86 are controlled, as shown by arrow b4 in Figure 6(C), and the transport hand 32 moves toward a predetermined standby position.

[0028] As mentioned above, the transport device 23 is equipped with a measurement unit 35 for measuring the outer edge data of the wafer W. Figures 7(A) and 7(B) show the measurement unit 35. Figures 7(A) and 7(B) also show partial cross-sectional views of the measurement unit 35 to illustrate its internal structure.

[0029] As shown in Figure 7(A), the measuring unit 35 includes a base plate 95 to which a housing case (case) 93 and an air cylinder 94 are attached, and a lifting table 96 connected to the telescopic rod 94a of the air cylinder 94. The lifting table 96 is provided with a mounting base 97 on which a laser displacement meter (measuring instrument) 34 is installed, and a waterproof cover 98 that covers the laser displacement meter 34. In addition, two supply and discharge pipes 99 and 100 are connected to the air cylinder 94 in order to drive the air cylinder 94 connected to the lifting table 96. An air chamber 102 is connected to these supply and discharge pipes 99 and 100 via an electromagnetic valve 101, and an air pump 103 is connected to the air chamber 102.

[0030] The electromagnetic valve 101 is operable in a lowering state, which lowers the lifting table 96, and an upward state, which raises the lifting table 96. By controlling the electromagnetic valve 101 to the lowering state, the supply and exhaust pipe 99 and the air chamber 102 are connected to each other, and the supply and exhaust pipe 100 and the exhaust port 104 are connected to each other. As a result, as shown in Figure 7(A), 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 housed in the housing case 93. On the other hand, by controlling the electromagnetic valve 101 to the upward state, the supply and exhaust pipe 99 and the exhaust port 105 are connected to each other, and the supply and exhaust pipe 100 and the air chamber 102 are connected to each other. As a result, as shown in Figure 7(B), the telescopic rod 94a of the air cylinder 94 can be extended, so that the lifting table 96 can be raised so that the laser displacement meter 34 is exposed from the housing case 93.

[0031] Thus, the laser displacement meter 34 provided on the measurement unit 35 is movable between a storage position where it is housed in the housing case 93 and a measurement position where it is extended out of the housing case 93. As shown in Figure 7(B), by moving the laser displacement meter 34 to the measurement position, the laser displacement meter 34 is positioned radially outward of the wafer W on the polishing stage 30. This allows laser light to be irradiated from the laser displacement meter 34 toward the outer edge E of the wafer W, making it possible to measure the position of the outer edge E of the wafer W using the laser displacement meter 34. Furthermore, the laser displacement meter 34 is communicated with a control unit 116 which constitutes the control system 120 described later.

[0032] [Control System] As shown in Figure 1, the wafer manufacturing line 10 is equipped with multiple control units 110 to 118 to control polishing devices 13, 18, 22, 26 and transport devices 15, 19, 23, 27, etc. The control units of the wafer manufacturing line 10 include control units 110 to 113 for each polishing device 13, 18, 22, 26, and control units 114 to 117 for each transport device 15, 19, 23, 27. Furthermore, the wafer manufacturing line 10 is equipped with a main control unit 118 that provides integrated control of these control units. Each of the control units 110 to 118 is connected to each other via a wired or wireless communication network 119. Each of the control units 110 to 118 in the wafer manufacturing line 10 has a microcontroller incorporating a processor and main memory. A predetermined program is stored in the main memory, and the processor executes the program's instruction set. Furthermore, control units 110 to 118 are provided with input circuits, drive circuits, and external memory, etc.

[0033] Furthermore, to control the wafer transfer device 23, which is one embodiment of the present invention, a control system 120 is configured by two control units 112 and 116. Here, Figure 8 shows an example of the control system 120. As shown in Figure 8, the control system 120 is configured by a control unit 112 that controls the polishing device 22 and a control unit 116 that controls the transfer device 23. The control unit 112 can control the stage rotation motor 41, the stage lifting motor 39, the electromagnetic valve 57 and the drum rotation motor 62, etc. The control unit 116 can control the transfer motor 75, the adjustment actuator 83, the lifting actuator 86, the first arm section 89, the second arm section 90, the laser displacement meter 34 and the electromagnetic valve, etc.

[0034] [Transport position correction control] Figure 9 shows the polishing stage 30 and the wafer W. As mentioned 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 portion of Figure 9, if the wafer center Cw, which is the center position of the wafer W, is off-center from the stage center Cs, which is the center position of the polishing stage 30, it is difficult to uniformly polish the outer edge E of the wafer W. Therefore, if the wafer center Cw is off-center from the stage center Cs, the control system 120 performs transport position correction control to correct the transport position of the wafer W by the transport unit 33.

[0035] Figure 10 is a flowchart showing an example of the procedure for executing transport position correction control. Figure 11 shows the transport device 23 and polishing device 22 during transport position correction control, and Figures 12(A) and (B) show the stage unit 20 and measuring unit 35 during transport position correction control. Figure 12(A) shows a plan view of the stage unit 20, as well as a plan view of the measuring unit 35 with the waterproof cover 98 removed. Figure 12(B) shows a side view of the stage unit 20, as well as a side view of the measuring unit 35 with the waterproof cover 98 attached.

[0036] As shown in Figure 10, in step S10, it is determined whether or not the wafer W has been transported to the polishing stage 30 by the transport unit 33. If it is determined in step S10 that the wafer W has been transported to the polishing stage 30, the process proceeds to step S11, where the transport count C1 is counted, and then to step S12, where it is determined whether or not the transport count C1 exceeds a predetermined number X1. If it is determined in step S12 that the transport count C1 exceeds the predetermined number X1, the process proceeds to step S13, where the transport count C1 is reset, and then to step S14, where the laser displacement meter 34 is moved to the measurement position. That is, as shown in Figures 11 and 12, by raising the lifting table 96 of the measurement unit 35, the laser displacement meter 34 moves out of the housing case 93 to a measurement position located radially outward of the wafer W. Note that the arrow r1 shown in Figure 12 indicates the radial direction of the wafer W.

[0037] As described above, when the laser displacement meter 34 is moved to the measurement position, the process proceeds to step S15, where the polishing stage 30 is rotated 360°, and the position of the outer edge E of the wafer W (outer edge data) is measured by the laser displacement meter 34. In other words, as shown in Figure 12(A), the polishing stage 30, i.e., the wafer W, is rotated in the direction of arrow r2 using the stage rotation motor 41. Also, as shown by the dashed line L in Figure 12(A), laser light is shone from the laser displacement meter 34 toward the outer edge E, and the laser light reflected from the outer edge E is captured by the laser displacement meter 34. As a result, as shown in the enlarged portion of Figure 12(A), the positions of multiple measurement points Pm set on the outer edge E of the wafer are measured by the laser displacement meter 34.

[0038] Here, Figure 13 shows an example of the displacement of the outer edge E measured by the laser displacement meter 34. When the wafer center Cw is off-center from the stage center Cs, as shown in Figure 13, the laser displacement meter 34 detects the position, i.e., displacement, of the outer edge E, which changes according to the rotation angle of the polishing stage 30. The laser displacement meter 34 may measure the position of the outer edge E at predetermined rotation angle intervals, or it may measure the position of the outer edge E continuously. In other words, the measurement points Pm set on the wafer outer edge E may be set at predetermined intervals in the circumferential direction, or they may be set continuously in the circumferential direction. As shown in Figure 10, when the position of the wafer outer edge E is measured by the laser displacement meter 34 in step S15, the process proceeds to step S16, where the lifting table 96 of the measurement unit 35 is lowered, moving the laser displacement meter 34 to its storage position in the housing case 93.

[0039] Next, in step S17, based on the position of the outer edge E of the wafer measured by the laser displacement meter 34, the center coordinates (Xa, Ya) of the wafer W are calculated with the center coordinates of the polishing stage 30 as the origin. In other words, the contour data of the wafer W is generated from the position data of the outer edge E of the wafer, and the center coordinates (Xa, Ya) of the wafer W are calculated from the contour data of the wafer W. Also in step S17, as shown in Figure 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 central axis passing through the stage center Cs and the central axis passing through the wafer center Cw. The XY plane is a plane perpendicular to the Z direction.

[0040] In the following step S18, it is determined whether the eccentricity α exceeds a predetermined threshold X2. If it is determined in step S18 that the eccentricity α exceeds the threshold X2, the process proceeds to step S19, where the adjustment actuator 83 of the transport unit 33 is controlled so that the wafer center Cw approaches the stage center Cs. In other words, 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". In the following step S20, the target travel 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. In other words, the target travel 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".

[0041] Furthermore, if it is determined in step S10 that the wafer W has not been transported to the polishing stage 30, or if it is determined in step S12 that the transport count C1 is less than or equal to a predetermined count X1, the routine is exited without controlling the adjustment actuator 83 or correcting the target travel distance D1. Also, if it is determined in step S18 that the eccentricity α is less than or equal to a threshold X2, the routine is exited without controlling the adjustment actuator 83 or correcting the target travel distance D1.

[0042] Here, Figures 14(A) and (B) show the position of the wafer center Cw relative to the stage center Cs. Figure 14(A) shows the situation before the transport position is corrected, and Figure 14(B) shows the situation after the transport position is corrected. As shown in Figure 14(A), if the eccentricity α of the wafer center Cw relative to the stage center Cs exceeds the threshold X2, the coordinates (Xa, Ya) of the wafer center Cw relative 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". In addition, the target movement 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".

[0043] As a result, as shown in Figure 14(B), the wafer W can be transported using the transport unit 33 so that the wafer center Cw aligns with the stage center Cs during the next transport. In other words, the transport accuracy of the wafer W relative to the polishing stage 30 can be improved, and since the centers of the polishing stage 30 and the wafer W can be aligned with each other, the polishing accuracy of the outer edge E of the wafer W can be improved. Moreover, since the eccentricity α of the wafer center Cw relative to the stage center Cs is determined periodically in the wafer manufacturing line 10, polishing defects due to misalignment of the wafer W can be significantly reduced.

[0044] Furthermore, by measuring the outer edge data of the wafer W using the laser displacement meter 34, the outer edge data can be measured without contacting the wafer W. This makes it possible to acquire outer edge data without compromising the quality of the wafer W. In addition, the laser displacement meter 34, which is a measuring instrument, is movable between a storage position where it is housed in the housing case 93 and a measurement position where it is extended out of the housing case 93. This allows the laser displacement meter 34 to be moved to the storage position when polishing the wafer W with the polishing drum 31, thereby properly protecting the laser displacement meter 34 from the polishing liquid that is scattered during the polishing process.

[0045] The present invention is not limited to the embodiments described above, and it goes without saying that various modifications are possible without departing from the spirit of the invention. For example, in the above description, the control system 120 is configured by two control units 112 and 116, but it is not limited to this, and the control system 120 may be configured by one control unit, or by three or more control units. Also, 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 it is not limited to this, and the X direction and the Y direction may intersect 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°. Furthermore, 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 into the adjustment actuator 83 that drives the second slider 82.

[0046] In the above description, a laser displacement meter 34 using laser light is used as the measuring instrument, but it is not limited to this, and any instrument that can acquire outer edge data of wafer W in a non-contact manner may be used. For example, an ultrasonic displacement meter, a capacitive displacement meter, or an eddy current displacement meter may be used as the measuring instrument. Also, for example, an imaging camera that images the contour of the outer edge E of the wafer may be used as the measuring instrument. Even when an imaging camera is used as the measuring instrument, the contour data of wafer W can be detected as outer edge data of wafer W, and the wafer center Cw can be calculated from the contour data of wafer W. Furthermore, in the above description, a notch is formed on wafer W, but it is not limited to this, and an orientation flat may be formed on wafer W. [Explanation of Symbols]

[0047] 23. Transport equipment (wafer transport equipment) 27. Conveying equipment (wafer conveying equipment) 28 Conveyor Hand 30 polishing stages 32 Conveyor Hand 34. Laser displacement meter (measuring instrument) 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 Storage Case (Case) 120 Control Systems W wafer E outer edge XX direction (first direction) YY direction (second direction) D1 Target distance traveled (Target distance) Cw wafer center Cs Stage Center α Eccentricity X2 threshold

Claims

1. A wafer transport apparatus for transporting a wafer to a polishing stage for polishing the outer edge of the wafer, A first slider is mounted on a first guide rail extending in a first direction and driven in the first direction by a first actuator, A second slider is 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, which grips the wafer being transported to the polishing stage, A control system that controls the first actuator to move the transport hand in the first direction by a target distance and transport the wafer to the polishing stage, A laser displacement meter, which is communicably connected to the control system and measures the outer edge data of the wafer transported to the polishing stage, It has, The laser displacement meter, positioned radially outward of the wafer, measures the outer edge data, which is the position of multiple measurement points on the outer edge of the wafer, while the polishing stage is rotating. The control system calculates the wafer center, which is the central position of the wafer, based on the outer edge data, and calculates the eccentricity of the wafer center with respect to the stage center, which is the central position of the polishing stage. The control system, when the eccentricity exceeds a threshold, controls the second actuator based on the eccentricity to move the transport hand in the second direction, and corrects the target distance during wafer transport based on the eccentricity. Wafer transport equipment.

2. In the wafer transport apparatus according to claim 1, The laser displacement meter is movable between a storage position where it is housed in a case and a measurement position where it is located radially outward from the wafer, outside the case. Wafer transport equipment.

3. A wafer transport apparatus for transporting a wafer to a polishing stage for polishing the outer edge of the wafer, A first slider is mounted on a first guide rail extending in a first direction and driven in the first direction by a first actuator, A second slider is 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, which grips the wafer being transported to the polishing stage, A control system that controls the first actuator to move the transport hand in the first direction by a target distance and transport the wafer to the polishing stage, A measuring instrument that is communicatively connected to the control system and measures the outer edge data of the wafer transported to the polishing stage, It has, The measuring instrument is movable between a storage position where it is housed in a case and a measurement position where it is removed from the case to measure the outer edge data. The control system calculates the wafer center, which is the central position of the wafer, based on the outer edge data, and calculates the eccentricity of the wafer center with respect to the stage center, which is the central position of the polishing stage. The control system, when the eccentricity exceeds a threshold, controls the second actuator based on the eccentricity to move the transport hand in the second direction, and corrects the target distance during wafer transport based on the eccentricity. Wafer transport equipment.

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