Polishing system, wafer transport control method, and work hole detection method

Abstract

To provide a workpiece hole detection device which can prevent polishing of a wafer that is not arranged in a determined attitude at a determined position.SOLUTION: A workpiece hole detection device for detecting the position of a workpiece hole 14 of a carrier 13 arranged on a lower surface plate 12 of a polishing machine 10 includes: a laser displacement gauge R for measuring a distance to an object T; an edge detection part 33 for detecting the positions of three or more edge parts of the workpiece hole 14 using the measurement value of the laser displacement gauge R; a center calculation part 34 for calculating the center position of the workpiece hole 14 on the basis of the positions of the three or more edge parts detected by the edge detection part 33; and a wafer state estimation part 36 for estimating the wafer conveyance state, on the basis of the upper face height of the conveyed wafer measured by the laser displacement gauge R.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a workpiece hole detection device that detects the positions of workpiece holes in a carrier that holds a wafer to be polished by a polisher, a workpiece hole detection method, a polishing system, and a wafer transport control method. [Background technology]

[0002] Conventionally, there has been known a workpiece hole detection device that detects the position of a workpiece hole of a carrier that holds a wafer when the wafer is polished by a polishing machine (see, for example, Patent Document 1). In the conventional workpiece hole detection device, image data is acquired by two cameras that are installed to form a predetermined central angle. Then, the center position of the workpiece hole is detected based on the positions of two points on the edge part of the workpiece hole obtained from the image data and the central angle between the cameras. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 4492155 Summary of the Invention [Problem to be solved by the invention]

[0004] However, when image data is used to detect the center position of the work hole, the quality of the image data varies due to the influence of the lighting conditions around the carrier, and it is considered that the edge part of the work hole cannot be detected properly. In addition, since image data is used, a problem occurs in that it is difficult to detect the edge part of the work hole when the color of the carrier and the polishing surface (polishing pad, etc.) of the base on which the carrier is placed are similar.

[0005] An object of the present invention is to provide a work hole detection device, a work hole detection method, a polishing system, and a wafer transport control method that can prevent polishing of a wafer that is not placed in a specified position and with a specified attitude. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention is a workhole detection device that detects the position of a workhole of a carrier placed on a polishing machine table, and comprises a distance measurement unit that measures the distance to an object, an edge detection unit that uses the measurement values ​​of the distance measurement unit to detect the positions of three or more edge portions of the workhole, a center calculation unit that calculates the center position of the workhole based on the positions of the three or more edge portions detected by the edge detection unit, and a wafer state estimation unit that estimates the transport state of the wafer based on the top surface height of the transported wafer measured by the distance measurement unit. Effect of the Invention

[0007] As a result, it is possible to prevent polishing of a wafer that is not placed at a predetermined position in a predetermined attitude. [Brief description of the drawings]

[0008] [Figure 1] 1 is a side view showing an outline of the overall configuration of a polishing system to which the work hole detection device of Example 1 is applied. [Diagram 2] 1 is a plan view showing an outline of the overall configuration of a polishing system to which the work hole detection device of Example 1 is applied. [Diagram 3] FIG. 2 is an explanatory diagram showing the measurement principle of a laser displacement meter. [Figure 4] 10 is an explanatory diagram showing various detection positions set when detecting a workpiece and the edge positions to be detected. FIG. [Diagram 5] 11 is an explanatory diagram showing various detection positions set when estimating a wafer transport state and a movement trajectory of a laser displacement meter; FIG. [Figure 6]FIG. 13 is a diagram showing measurement values ​​of a laser displacement meter when detecting an edge position. [Figure 7] 1A is an explanatory diagram showing a wafer state when the wafer is normally transferred, and FIG. 1B is a diagram showing measured values ​​of a laser displacement meter when the wafer is normally transferred. [Figure 8] 1A is an explanatory diagram showing a wafer state when the wafer lands on the support member, FIG. 1B is a first diagram showing the measured value of the laser displacement meter when the wafer lands on the support member, and FIG. 1C is a second diagram showing the measured value of the laser displacement meter when the wafer lands on the support member. [Figure 9] 1A is an explanatory diagram showing a wafer state when the wafer is floating, and FIG. 1B is a diagram showing measured values ​​of a laser displacement meter when the wafer is floating. [Figure 10] 4 is a flowchart showing a wafer transfer control process executed by a main controller in the first embodiment. [Figure 11] 13 is an explanatory diagram showing another example of setting the edge detection position. FIG. [Figure 12] 1A is an explanatory diagram showing a first modified example of a movement trajectory of a laser displacement meter when estimating a wafer transport state, and FIG. 1B is a diagram showing a detection value of the laser displacement meter when the wafer rides up, when the wafer upper surface height is detected along the movement trajectory of the first modified example. [Figure 13] 1A is an explanatory diagram showing a second modified example of the movement trajectory of the laser displacement meter when estimating the wafer transport state, and FIG. 1B is a diagram showing the detection value of the laser displacement meter when the wafer rides up, when the wafer upper surface height is detected along the movement trajectory of the second modified example. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0009] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, a workpiece hole detection device, a workpiece hole detection method, a polishing system, and a wafer transport control method according to the present invention will be described with reference to a first embodiment shown in the drawings.

[0010] Example 1 Hereinafter, the configuration of a polishing system 1 to which the work hole detection device of the first embodiment is applied will be described with reference to FIGS.

[0011] The polishing system 1 shown in FIG. 1 includes a polishing machine 10, a wafer transport machine 20, and a main controller 30.

[0012] The polishing machine 10 is a double-sided polishing device that polishes both the front and back sides of a thin wafer 2 by means of an upper platen 11 and a lower platen 12. Here, the wafer 2 is polished by a polishing pad 11a attached to the upper platen 11 and a polishing pad 12a attached to the lower platen 12. As shown in FIG. 2, the wafer 2 is accommodated in a work hole 14 of a carrier 13 arranged above the polishing pad 12a, and is held by the carrier 13 and polished.

[0013] The carrier 13 is a disk-shaped thin plate member that is thinner than the wafer 2. The work hole 14 is a hole that penetrates the carrier 13, and is set to have an inner diameter dimension that is slightly larger than the diameter of the wafer 2. In the example shown in Fig. 2, one work hole 14 is formed in the carrier 13, but the number of work holes 14 formed in the carrier 13 can be set as desired.

[0014] When the carrier 13 is placed on the polishing pad 12a, the circumferential direction and position are specified, and the moving trajectory is constantly monitored by, for example, a controller (not shown) of the polishing machine 10. This allows the relative positional relationship between the lower surface plate 12 and the carrier 13 to be constantly grasped, and the center position of the work hole 14 can be obtained by calculation based on this positional relationship. The center position of the work hole 14 calculated based on the relative positional relationship between the lower surface plate 12 and the carrier 13 is hereinafter referred to as "teaching position α (see FIG. 4)". This teaching position α is specified in the XY coordinate system of the wafer transport machine 20.

[0015] The wafer transport machine 20 is a robot arm that is driven based on a control command from the main controller 30 and automatically transports the wafers 2 one by one. The wafer transport machine 20 includes a transport head 21 that detachably holds the wafer 2, and an arm unit 22 that moves the transport head 21 in horizontal and vertical directions.

[0016] Prior to polishing the wafer 2, this wafer transport machine 20 holds the wafer 2 taken out from a load port (not shown) that stores a large number of wafers 2 with the transport head 21. Next, the arm unit 22 is moved to transport the transport head 21 to a position above a predetermined work hole 14. Then, the wafer 2 is released from the transport head 21 and placed in the work hole 14.

[0017] After polishing the wafer 2, the wafer transport machine 20 moves the arm unit 22 to move the transport head 21 to a position above a predetermined work hole 14. Next, the transport head 21 holds the wafer 2 in the work hole 14 and removes the wafer 2. Then, the arm unit 22 is moved to transport the wafer 2 to an unload port (not shown).

[0018] Furthermore, the transport head 21 of the embodiment 1 is equipped with a laser displacement meter R (distance measurement unit). As shown in Fig. 3, this laser displacement meter R is a distance sensor that irradiates a laser beam S1 onto an object T and measures a distance L to the object T in a non-contact manner based on a reflected beam S2 reflected by the object T.

[0019] This laser displacement meter R moves integrally with the transport head 21 when the arm unit 22 is driven to move the transport head 21. In addition, since the wafer transport machine 20 can move the laser displacement meter R while maintaining a constant height position, the laser displacement meter R can measure the thickness of the carrier 13. In addition, this laser displacement meter R can measure the distance to the object T even while being moved by the wafer transport machine 20. Note that, during measurement by the laser displacement meter R, air may be sprayed onto the object T to remove moisture adhering to the object T.

[0020] The main controller 30 outputs a control command to the wafer transporter 20 to control the transport of the wafer 2 by the wafer transporter 20, and controls the movement of the laser displacement meter R by the movement of the transport head 21. The main controller 30 also calculates a teaching position α based on the relative positional relationship between the lower surface plate 12 and the carrier 13, and detects the positions of the edge parts of the work hole 14 at three or more locations (four locations in the first embodiment) using the teaching position α. ​​Here, the "edge part" refers to the inner peripheral edge part of the work hole 14, and is the boundary between the work hole 14 and the carrier 13. Then, the center position of the work hole 14 is calculated based on the position of the detected edge part. The positions of the edge parts of the work hole 14 and the center position of the work hole 14 are both specified in the XY coordinate system of the wafer transporter 20. Furthermore, after the transport of the wafer 2, the main controller 30 estimates the transport state of the wafer based on the height of the top surface of the transported wafer.

[0021] That is, the main controller 30 includes a teaching position calculation unit 31, a detection position setting unit 32, an edge detection unit 33, a center calculation unit , a transfer control unit 35, and a wafer state estimation unit .

[0022] When information on the relative positional relationship between the lower platen 12 and the carrier 13 is input, the teaching position calculation unit 31 calculates a teaching position α based on this positional relationship information. The positional relationship information between the lower platen 12 and the carrier 13 is input from, for example, the controller of the polishing machine 10. Information on the teaching position α calculated by the teaching position calculation unit 31 is input to the detection position setting unit 32.

[0023] When information on the teaching position α is input from the teaching position calculation unit 31, the detection position setting unit 32 sets various detection positions when detecting the position of the work hole 14 based on this teaching position information. In addition, after the wafer 2 is transported, information on the center position of the work hole 14 (hereinafter referred to as "actual center position β (see FIG. 5)") calculated by the center calculation unit 34 is input to the detection position setting unit 32. Then, based on this actual center position information, various detection positions are set when estimating the transport state of the wafer 2. Here, the "detection position" refers to the movement target point of the laser displacement meter R. Information on the detection position set by the detection position setting unit 32 is input to the transport control unit 35.

[0024] Here, when detecting the position of the workpiece hole 14, the height of the carrier 13, which is a reference value when detecting the edge of the workpiece hole 14, and four positions, namely, the first edge position P11, the second edge position P13, the third edge position P15, and the fourth edge position P17 (see FIG. 4) are detected. Therefore, the detection position setting unit 32 sets the reference detection position P10, the first edge detection position P12, the second edge detection position P14, the third edge detection position P16, and the fourth edge detection position P18 shown in FIG. 4. The "reference detection position P10" is the movement target point of the laser displacement meter R when detecting the height of the carrier 13. The "first edge detection position P12" is the movement target point of the laser displacement meter R when detecting the first edge position P11. The "second edge detection position P14" is the movement target point of the laser displacement meter R when detecting the second edge position P13. The "third edge detection position P16" is a target point to which the laser displacement meter R moves when detecting the third edge position P15. The "fourth edge detection position P18" is a target point to which the laser displacement meter R moves when detecting the fourth edge position P17.

[0025] In addition, the first edge detection position P12, the second edge detection position P14, the third edge detection position P16, and the fourth edge detection position P18 are set at positions that can surround the teaching position α by a line segment γ that sequentially connects these four positions, as shown in Fig. 4. In other words, when setting the edge detection positions, the detection position setting unit 32 sets three or more detection positions that can surround the teaching position α.

[0026] The reference detection position P10 is set to a position that is estimated to be the substrate portion of the carrier 13 based on the teaching position α. ​​The "substrate portion of the carrier 13" is a position outside the workpiece holes 14, and is a flat portion where no workpiece holes 14 or waste holes are formed. The first edge detection position P12, the second edge detection position P14, the third edge detection position P16, and the fourth edge detection position P18 are all set to positions that are estimated to be inside the workpiece holes 14 based on the teaching position α.

[0027] Furthermore, when estimating the transport state of the wafer 2, in the first embodiment, the height of the carrier 13, which is a reference value for determining the wafer transport state, and the height of the top surface of the transported wafer 2 are detected. For this purpose, the detection position setting unit 32 sets a reference detection position P20 and a height detection start position P21 shown in FIG. 5. The "reference detection position P20" is a movement target point of the laser displacement meter R when detecting the height of the carrier 13. The "height detection start position P21" is a movement target point of the laser displacement meter R when detecting the top surface height of the wafer 2.

[0028] Here, the reference detection position P20 is set to a position that is estimated to be the substrate portion of the carrier 13 based on the actual center position β. Also, the height detection start position P21 is set to a position that is estimated to be the wafer 2 based on the actual center position β.

[0029] When the measurement value of the laser displacement meter R is input, the edge detection unit 33 detects three or more positions of the edge portion of the work hole 14 (four positions, namely, the first edge position P11 to the fourth edge position P17 in the first embodiment) based on the measurement value. Position information of the edge portion detected by the edge detection unit 33 is input to the center calculation unit 34.

[0030] When detecting an edge portion, the edge detection unit 33 first sets a reference value based on a measurement value obtained by moving the laser displacement meter R to a reference detection position P10. Here, the reference value is a value obtained by subtracting a predetermined value from the measurement value obtained at the reference detection position P10. Next, it is determined whether or not a measurement value obtained while moving the laser displacement meter R along a predetermined trajectory from a first edge portion detection position P12 exceeds the reference value. Then, a first edge position P11 is detected based on the movement amount x of the laser displacement meter R at the time when the measurement value exceeds the reference value and the first edge portion detection position P12 (see FIG. 6).

[0031] Note that the edge detection unit 33 also detects the second edge position P13, the third edge position P15, and the fourth edge position P17 in the same manner as the first edge position P11 each time the laser displacement meter R is moved. That is, the edge detection unit 33 repeats detecting the position of the edge portion (the first edge position P11, etc.) while moving the laser displacement meter R from the edge portion detection position (the first edge portion detection position P12, etc.) until three or more edge portion positions (the first edge position P11, etc.) are detected.

[0032] The center calculation unit 34 receives position information of three or more edge portions (four positions, namely, the first edge position P11 to the fourth edge position P17, in the first embodiment) from the edge detection unit 33. Then, the center calculation unit 34 calculates the actual center position β based on this edge portion position information. Information on the actual center position β calculated by the center calculation unit 34 is input to the transport control unit 35. The actual center position β can be found by utilizing the position information of three or more edge portions and a general circle equation.

[0033] The transport control unit 35 receives information on various detection positions (reference detection position P10, etc.) from the detection position setting unit 32, and outputs a control command to the wafer transport machine 20 based on the various detection positions. Then, the transport control unit 35 moves the laser displacement meter R to the various detection positions as movement target points in a predetermined order and timing. After moving the laser displacement meter R to a predetermined detection position (first edge position P11, etc.), the transport control unit 35 outputs a control command to the wafer transport machine 20 to move the laser displacement meter R in a predetermined direction.

[0034] After the wafer 2 is transported, the measurement value of the laser displacement meter R is input to the wafer state estimation unit 36, and the wafer state estimation unit 36 ​​estimates the transport state of the transported wafer 2 based on the measurement value. Note that the transport state information estimated by the wafer state estimation unit 36 ​​may be input to, for example, a controller of the polishing machine 10 and notified to an operator of the polishing system 1.

[0035] When estimating the transport state of the wafer, the wafer state estimation unit 36 ​​first sets a reference range (upper and lower thresholds) based on the measurement value obtained when the laser displacement meter R is moved to a reference detection position P20. Then, the laser displacement meter R is moved to a height detection start position P21, and a measurement value (wafer upper surface height) obtained while moving from the height detection start position P21 along a predetermined trajectory (here, a circular trajectory 3 along the peripheral portion of the wafer 2) is judged as to whether it exceeds the reference range.

[0036] For example, as shown in Fig. 7(a), when the wafer 2 is properly placed in the work hole 14, the measurement value obtained while the laser displacement meter R moves along the circular trajectory 3 falls within the reference range (see Fig. 7(b)). That is, when the wafer state estimation unit 36 ​​determines that the measurement value falls within the reference range, it estimates that the wafer 2 is properly placed.

[0037] On the other hand, as shown in FIG. 8(a), when the wafer 2 runs over the edge of the work hole 14, the measured value of the laser displacement meter R exceeds the reference range during the measurement while the laser displacement meter R moves along the circular track 3 (see FIG. 8(b)). Note that, depending on the relationship between the set position of the height detection start position P21 and the run-up position of the wafer 2, the measured value shown in FIG. 8(c) is obtained, but even in this case, the measured value of the laser displacement meter R exceeds the reference range during the measurement while the laser displacement meter R moves along the circular track 3. Furthermore, as shown in FIG. 9(a), even if the wafer 2 is placed in the work hole 14, if it is lifted off the polishing pad 12a due to the influence of slurry, water, or the like, the measured value of the laser displacement meter R exceeds the reference range during the measurement while the laser displacement meter R moves along the circular track 3 (see FIG. 9(b)). Therefore, when the wafer state estimation unit 36 ​​determines that the measured value exceeds the reference range, it estimates that the wafer 2 is not placed normally.

[0038] Hereinafter, each step of the wafer transport control process executed by the main controller 30 in the first embodiment will be described with reference to the flowchart shown in Fig. 10. Note that this wafer transport control process is repeatedly executed until the wafers 2 are placed in the work holes 14 of all the carriers 13 on the polishing pad 12a.

[0039] In step S1, it is determined whether or not to start the transfer of the wafer 2. If YES (transfer start), proceed to step S2. If NO (transfer not performed), repeat step S1. The transfer start determination is performed by, for example, the transfer control unit 35.

[0040] In step S2 (first step), following the determination in step S1 that conveyance should be started, the teaching position calculation unit 31 calculates a teaching position, the detection position setting unit 32 reads information on the calculated teaching position α, and the process proceeds to step S3.

[0041] In step S3 (first step), following the reading of the teaching position information in step S2, the detection position setting unit 32 sets various detection positions (reference detection position P10, first edge detection position P12, second edge detection position P14, third edge detection position P16, and fourth edge detection position P18) when detecting the position of the work hole 14 based on the teaching position information, and proceeds to step S4.

[0042] In step S4 (first step), following the setting of the detection position in step S3, a control command is output from the transport control unit 35 to the wafer transport machine 20, and the laser displacement meter R is moved to the reference detection position P10 set in step S3 as the movement target point, and the process proceeds to step S5.

[0043] In step S5 (first step), following the movement of the laser displacement meter R in step S4, the distance to the reference detection position P10 is measured by the laser displacement meter R, and the process proceeds to step S6. Here, since the reference detection position P10 is set to a position estimated to be the substrate portion of the carrier 13, the carrier height is detected. Then, based on this carrier height, a reference value for detecting the edge portion of the work hole 14 is set.

[0044] In step S6 (first step), following the detection of the carrier height in step S5, a control command is output from the transport control unit 35 to the wafer transport machine 20, and the laser displacement meter R is moved to the first edge detection position P12 set in step S3 as the target point for movement, and the process proceeds to step S7.

[0045] In step S7 (first step), following the movement of the laser displacement meter R in step S6, the laser displacement meter R is moved in a predetermined direction while measuring the distance to the carrier 13 or polishing pad 12a present below. Then, based on the measurement value obtained at this time and a reference value set from the carrier height detected in step S5, the edge detection unit 33 detects the first edge position P11, and the process proceeds to step S8.

[0046] In step S8 (first step), following the detection of the first edge position P11 in step S7, a control command is output from the transport control unit 35 to the wafer transport machine 20, and the laser displacement meter R is moved to the second edge detection position P14 set in step S3 as the movement target point, and the process proceeds to step S9.

[0047] In step S9 (first step), following the movement of the laser displacement meter R in step S8, the laser displacement meter R is moved in a predetermined direction while measuring the distance to the carrier 13 or polishing pad 12a present below by the laser displacement meter R. Then, based on the measurement value obtained at this time and the reference value set in step S5, the edge detection unit 33 detects the second edge position P13, and the process proceeds to step S10.

[0048] In step S10 (first step), following the detection of the second edge position P13 in step S9, a control command is output from the transport control unit 35 to the wafer transport machine 20, and the laser displacement meter R is moved to the third edge detection position P16 set in step S3 as the movement target point, and the process proceeds to step S11.

[0049] In step S11 (first step), following the movement of the laser displacement meter R in step S10, the laser displacement meter R is moved in a predetermined direction while measuring the distance to the carrier 13 or polishing pad 12a present below by the laser displacement meter R. Then, based on the measurement value obtained at this time and the reference value set in step S5, the edge detection unit 33 detects the third edge position P15, and the process proceeds to step S12.

[0050] In step S12 (first step), following the detection of the third edge position P15 in step S11, a control command is output from the transport control unit 35 to the wafer transport machine 20, and the laser displacement meter R is moved to the fourth edge detection position P18 set in step S3 as the movement target point, and the process proceeds to step S13.

[0051] In step S13 (first step), following the movement of the laser displacement meter R in step S12, the laser displacement meter R is moved in a predetermined direction while measuring the distance to the carrier 13 or polishing pad 12a present below. Then, based on the measurement value obtained at this time and the reference value set in step S5, the edge detection unit 33 detects the fourth edge position P17, and the process proceeds to step S14.

[0052] In step S14 (second step), following the detection of the fourth edge position P17 in step S13, the center calculation unit 34 calculates the actual center position β based on the first edge position P11, the second edge position P13, the third edge position P15, and the fourth edge position P17, and the process proceeds to step S15.

[0053] In step S15, following the calculation of the actual center position β in step S14, the transfer control unit 35 outputs a control command to the wafer transfer machine 20 to transfer the wafer 2 into the work hole 14, and the process proceeds to step S16. At this time, the transfer control unit 35 calculates the difference (deviation) between the teaching position α calculated by the teaching position calculation unit 31 and the actual center position β calculated by the center calculation unit 34. Next, the transfer control unit 35 corrects the calculated difference (deviation) for the teaching position α to set a target position. Then, a control command is output to match the center position of the wafer 2 held by the transfer head 21 with this target position, and the arm unit 22 is controlled so that the wafer 2 is placed at the center of the work hole 14.

[0054] In step S16 (third step), following the transfer of the wafer 2 in step S15, the transfer control unit 35 outputs a control command to the wafer transfer machine 20 to detect the height of the upper surface of the transferred wafer 2, and the process proceeds to step S17.

[0055] Here, before detecting the height of the top surface of the wafer 2, the detection position setting unit 32 first sets a reference detection position P20 and a height detection start position P21 based on the actual center position β. Next, the transport control unit 35 moves the laser displacement meter R to the reference detection position P20, and the laser displacement meter R measures the distance to the reference detection position P20. The wafer state estimation unit 36 ​​sets a reference range (upper and lower thresholds) based on the measurement value obtained at this time. After that, the transport control unit 35 moves the laser displacement meter R to the height detection start position P21. Then, the laser displacement meter R detects the top surface height of the wafer 2 while moving from the height detection start position P21 along a loop trajectory 3 set in advance.

[0056] In step S17 (fourth step), following the detection of the top surface height of the wafer 2 in step S16, the wafer state estimation unit 36 ​​estimates the transport state of the wafer 2 based on the top surface height of the wafer 2 detected in step S16 and a reference range set from the distance to the reference detection position P20, and the process proceeds to the end.

[0057] The "workhole position detection action" of the workhole detection device and the workhole detection method of the first embodiment will be described below.

[0058] To polish the wafer 2 in the polishing system 1 of the first embodiment, the wafer 2 is automatically transported onto the lower platen 12 of the polishing machine 10 using the wafer transport machine 20. Here, a polishing pad 12a is attached to the lower platen 12 in advance, and a carrier 13 having a work hole 14 is placed on the polishing pad 12a. In other words, the wafer transport machine 20 needs to transport the wafer 2 into the determined work hole 14 in a determined attitude.

[0059] On the other hand, the circumferential direction and position of the carrier 13 when it is placed on the polishing pad 12a are regulated, and the movement trajectory is constantly monitored. Therefore, the relative positional relationship between the lower surface plate 12 and the carrier 13 is always known, and the center position of the work hole 14 is also obtained as the teaching position α. ​​However, due to backlash of the sun gear and internal gear of the polishing machine 10, backlash of the carrier, and an increase in backlash due to wear, the actual center position of the work hole 14 may deviate from the teaching position α. ​​Therefore, if the wafer 2 is transported with the teaching position α as the target position, there are cases where the wafer 2 cannot be transported appropriately.

[0060] Therefore, in the wafer transport machine 20 of the first embodiment, in order to recognize the position of the work hole 14 where the wafer 2 is to be placed, the positions of the edges of the work hole 14 in three or more places are detected using a laser displacement meter R before placing the wafer 2, and an actual center position β defined in the XY coordinate system of the wafer transport machine 20 is calculated. Then, the wafer 2 is placed by correcting the difference between this actual center position β and the previously obtained teaching position α.

[0061] 10, and when it is determined that the transfer of the wafer 2 should be started, step S2 is executed. As a result, the teaching position calculation unit 31 calculates the teaching position α, and the detection position setting unit 32 reads the information on the teaching position α calculated by the teaching position calculation unit 31.

[0062] Next, the detection position setting unit 32 executes step S3 and sets various detection positions (reference detection position P10, first edge detection position P12, second edge detection position P14, third edge detection position P16, and fourth edge detection position P18) when detecting the position of the work hole 14 based on the teaching position information.

[0063] Here, the first edge detection position P12, the second edge detection position P14, the third edge detection position P16, and the fourth edge detection position P18 are set at positions that can surround the teaching position α with a line segment γ that connects these four positions. Also, the reference detection position P10 is set at a position that is estimated to be the substrate portion of the carrier 13 based on the teaching position α.

[0064] Once the detection position is set by the detection position setting unit 32, steps S4 and S5 are executed, and the transport control unit 35 moves the laser displacement meter R to the reference detection position P10 as a movement target point, and the distance to the reference detection position P10 is measured by the laser displacement meter R. Here, the reference detection position P10 is a position where there is no work hole 14 of the carrier 13. Therefore, the laser displacement meter R can detect the height of the carrier 13.

[0065] Once the carrier height is detected, steps S6 and S7 are executed. That is, the transport control unit 35 moves the laser displacement meter R to the first edge detection position P12 as a movement target point. The laser displacement meter R measures the distance to the target object (the carrier 13 or the polishing pad 12a) while moving from the first edge detection position P12. The edge detection unit 33 compares the measurement value obtained at this time with a reference value obtained from the carrier height detected in advance, and detects the first edge position P11.

[0066] Once the first edge position P11 is detected, steps S8 and S9 are executed. That is, the transport control unit 35 moves the laser displacement meter R to the second edge detection position P14 as a movement target point. The laser displacement meter R measures the distance to the target object (the carrier 13 or the polishing pad 12a) while moving from the second edge detection position P14. The edge detection unit 33 compares the measurement value obtained at this time with a reference value obtained from the carrier height detected in advance, and detects the second edge position P13.

[0067] When the second edge position P13 is detected, steps S10 and S11 are executed. That is, the transport control unit 35 moves the laser displacement meter R to the third edge detection position P16 as a movement target point. The laser displacement meter R measures the distance to the target object (the carrier 13 or the polishing pad 12a) while moving from the third edge detection position P16. The edge detection unit 33 compares the measurement value obtained at this time with a reference value obtained from the carrier height detected in advance, and detects the third edge position P15.

[0068] When the third edge position P15 is detected, steps S12 and S13 are executed. That is, the transport control unit 35 moves the laser displacement meter R to the fourth edge detection position P18 as a movement target point. The laser displacement meter R measures the distance to the target object (the carrier 13 or the polishing pad 12a) while moving from the fourth edge detection position P18. The edge detection unit 33 compares the measurement value obtained at this time with a reference value obtained from the carrier height detected in advance, and detects the fourth edge position P17.

[0069] Once the four edge positions (first edge position P11, second edge position P13, third edge position P15, fourth edge position P17, and so on) have been detected, step S14 is executed, and the center calculation unit 34 calculates the actual center position β using the information on the four edge positions and the equation of the circle.

[0070] Then, when the actual center position β is calculated, the transfer control unit 35 executes step S15. That is, the transfer control unit 35 obtains the difference (deviation) between the teaching position α and the actual center position β, corrects the teaching position α based on this difference (deviation), and outputs a control command to align the center position of the wafer 2 with the set target position, and places the wafer 2 at the center of the work hole 14.

[0071] In this way, in the first embodiment, the actual center position β is detected based on information on the positions of the four edge portions, and the positions of the four edge portions are detected based on measurements obtained by measuring the distance to the object T while moving the laser displacement meter R that measures the distance to the object T. Therefore, the position of the edge portion of the work hole 14 can be detected without being affected by the lighting conditions around the detection device or the color of the carrier 13.

[0072] This makes it possible to stably detect the positions of the work holes 14 of the carrier 13 arranged on the lower platen 12 of the polishing machine 10. Since the positions of the work holes 14 can be stably grasped, it becomes possible to place the wafer 2 at a determined position with a determined attitude with high precision.

[0073] In addition, the distance to the target object T is measured by a laser displacement meter R that measures this distance by the reflected light of a laser beam. Therefore, the distance can be measured without contacting the carrier 13 or the polishing pad 12a, so that the distance L to the target object T can be measured with high accuracy while moving. This allows the position of the edge portion of the work hole 14 to be detected with high accuracy.

[0074] Furthermore, in the first embodiment, the laser displacement meter R is mounted on the transport head 21 of the wafer transport machine 20 that transports the wafer 2. Therefore, the laser displacement meter R can be moved by utilizing the wafer transport machine 20 that moves to the vicinity of the work hole 14, and even without providing a separate mechanism for moving the laser displacement meter R, the laser displacement meter R can be moved to an appropriate position and the position of the edge of the work hole 14 can be detected with high accuracy.

[0075] In addition, in the first embodiment, the relative positional relationship between the lower platen 12 and the carrier 13 is monitored, and the teaching position calculation unit 31 calculates the teaching position α based on the relative positional relationship between the lower platen 12 and the carrier 13. This allows the detection position setting unit 32 to set various detection positions when detecting the position of the work hole 14 based on the teaching position α. ​​In other words, the position of the edge of the work hole 14 can be detected using the teaching position α as a guide. This makes it possible to detect the position of the edge of the work hole 14 in a short time without having to move the laser displacement meter R unnecessarily.

[0076] Moreover, the edge detection positions (first edge detection position P12, second edge detection position P14, third edge detection position P16, fourth edge detection position P18, and so on) set by the detection position setting unit 32 are set at positions that can surround the teaching position α by the line segment γ connecting these four positions.

[0077] That is, when detecting the position of the edge of the work hole 14, the detection position setting unit 32 sets three or more edge detection positions that can surround the teaching position α. ​​Then, the edge detection unit 33 repeatedly detects the position of the edge of the work hole 14 while moving the laser displacement meter R from each edge detection position, and detects three or more positions of the edge of the work hole 14. Therefore, the positions of the edge of the work hole 14 detected by the edge detection unit 33 become positions that surround the teaching position α, as shown in Fig. 4, and the calculation accuracy when calculating the actual center position β based on the position of the edge of the work hole 14 can be improved.

[0078] Moreover, in the first embodiment, the positions of the edge portions at four locations are detected. Therefore, when calculating the actual center position β, four calculation formulas can be established, and the calculation accuracy can be improved compared to, for example, the case where the positions of the edge portions of the workpiece hole 14 are detected at three locations.

[0079] The "wafer transfer state estimation function" of the workpiece hole detection device and workpiece hole detection method of the first embodiment will be described below.

[0080] In the polishing system 1 of the first embodiment, after the wafer 2 is transported, step S16 in the flowchart shown in FIG. 10 is executed to set the upper surface height of the wafer 2. That is, first, the detection position setting unit 32 sets the reference detection position P20 and the height detection start position P21 based on the actual center position β. Then, the transport control unit 35 drives the wafer transport machine 20 to move the laser displacement meter R to the reference detection position P20 and measure the distance to this reference detection position P20. Here, the reference detection position P20 is a position estimated to be the substrate part of the carrier 13. Therefore, the laser displacement meter R can detect the height of the carrier 13. At this time, the wafer state estimation unit 36 ​​sets a reference range for estimating the transport state of the wafer 2 based on the carrier height. Then, the transport control unit 35 drives the wafer transport machine 20 to move the laser displacement meter R from the height detection start position P21 along the circular locus 3. The laser displacement meter R measures the distance to the wafer 2 while moving and detects the upper surface height of the wafer 2.

[0081] Once the top surface height of the wafer 2 is detected by the laser displacement meter R, step S17 is executed, and the wafer state estimation unit 36 ​​compares the detected top surface height of the wafer 2 with a preset reference range, and estimates the transport state of the wafer 2.

[0082] In this manner, in the first embodiment, the wafer state estimation unit 36 ​​is provided which estimates the transport state of the wafer 2 based on the top surface height of the transported wafer 2 measured by the laser displacement meter R.

[0083] As a result, when it is estimated that the wafer 2 is not placed at the specified position in the specified attitude, such as when the wafer 2 rides up on the edge of the work hole 14 (see FIG. 8(a)) or when the wafer 2 is floating above the polishing pad 12a (see FIG. 9(a)), this transport information is notified to an operator of the polishing system 1, making it possible to correct the position or attitude of the transported wafer 2 or to stop polishing the wafer 2. In other words, it is possible to prevent polishing of the wafer 2 that is not placed at the specified position in the specified attitude.

[0084] The workpiece detection device and the workpiece detection method of the present invention have been described above based on the first embodiment. However, the specific configuration is not limited to this embodiment, and design changes and additions are permitted as long as they do not deviate from the gist of the invention according to each claim in the claims.

[0085] In the first embodiment, an example is shown in which the edge detection positions are set at positions that can surround the teaching position α with a line segment γ that sequentially connects the four edge detection positions, but this is not limited to this. Since it is only necessary to detect the positions of the edges of the work hole 14 at three or more positions, as shown in Fig. 11, three or more edge detection positions (in the example shown in Fig. 11, the first edge detection position P12', the second edge detection position P14', the third edge detection position P16', and the fourth edge detection position P18') may be set at positions that do not surround the teaching position α. ​​In other words, the edge detection positions can be set arbitrarily.

[0086] In addition, in the first embodiment, an example has been shown in which all edge detection positions are set to positions that are estimated to be inside the work hole 14 based on the teaching position α, but this is not limiting. The edge detection positions may be set to the outside of the work hole 14 (positions estimated to be the substrate portion of the carrier 13). When the edge detection positions are set to positions inside the work hole 14 and the laser displacement meter R is moved from the inside to the outside of the work hole 14 while performing measurements, moisture adhering to the edge portion of the work hole 14 can be easily removed by blowing air onto the carrier 13 as the laser displacement meter R moves, and the occurrence of measurement errors can be suppressed.

[0087] Furthermore, the teaching position calculation unit 31 and the detection position setting unit 32 may not be provided, and the position of the edge of the work hole 14 may be detected using the measurement values ​​obtained while moving the laser displacement meter R from any position in any direction, without setting the edge detection position.

[0088] In addition, in the first embodiment, an example was shown in which the transport state of the wafer 2 was estimated based on the measurement value obtained by moving the laser displacement meter R along the circular trajectory 3 along the peripheral portion of the wafer 2. However, this is not limited to the above, as it is only necessary to detect the height of the transported wafer 2 at a plurality of positions.

[0089] For example, as shown in Fig. 12(a), the transport state of the wafer 2 may be estimated based on the measurement value obtained by moving the laser displacement meter R along two linear trajectories (first trajectory 4, second trajectory 5) that are perpendicular to each other at the actual center position β. In this case, as shown in Fig. 12(b), even if the measurement value obtained by moving the laser displacement meter R along the second trajectory 5 is a constant value, if the measurement value obtained by moving the laser displacement meter R along the first trajectory 4 exceeds the upper threshold value, the wafer state estimation unit 36 ​​determines that the measurement value obtained exceeds the reference range and estimates that the wafer 2 is not positioned normally.

[0090] 13(a), the laser displacement meter R may be moved to a position above any six measurement points (6a, 6b, 6c, 6d, 6e, 6f) near the periphery of the wafer 2, and the transport state of the wafer 2 may be estimated based on the height position of the wafer 2 at each of the measurement points 6a to 6f. In this case, as shown in FIG. 13(b), if any of the six measurement points 6a to 6f exceeds the reference range, the wafer state estimation unit 36 ​​estimates that the wafer 2 is not positioned normally.

[0091] In addition, in the first embodiment, an example has been shown in which the laser displacement meter R that measures the distance by the reflected light S2 of the laser light is used as the distance measuring unit that measures the distance to the object T, but the present invention is not limited to this. For example, a distance measuring device that extends an extendable measuring rod to the object T and measures the distance based on the length of the rod may be used.

[0092] In addition, in the first embodiment, an example is shown in which the wafer 2 is transported to one work hole 14 formed in the carrier 13, but a plurality of work holes 14 may be formed in the carrier 13. In this case, for example, the actual center positions of the plurality of work holes 14 can be detected one by one in sequence, and the wafer 2 can be placed in the work hole 14 whose actual center position has been detected in sequence.

[0093] Furthermore, the actual center position β of the work hole 14 may be detected while the wafer 2 is being held by the transport head 21, or may be detected while the wafer 2 is not being held. When the actual center position β is detected while the wafer 2 is being held, there is no need to drive the arm unit 22 to hold the wafer 2 after the actual center position β is detected. This makes it possible to suppress an increase in the transport time of the wafer 2. [Explanation of symbols]

[0094] 1 Polishing System 2 wafers 10 Polishing machine 11 Upper surface plate 12 Lower surface plate 13. Career 14 Work Hall 20 Wafer transport machine 21 Transport head 22 Arm section 30 Main Controller 31 Teaching position calculation unit 32 Detection position setting section 33 Edge detection section 34 Central calculation section 35 Transport control section 36 Wafer condition estimation unit R Laser displacement meter (distance measurement part) α Teaching position β Actual center position

Claims

1. A polishing system including a polishing machine that polishes a wafer by a surface plate, and a wafer transport machine that transports the wafer into a work hole of a carrier arranged on the surface plate, A distance measuring unit that measures a distance to an object; a wafer state estimation unit that estimates a transport state of the wafer based on the height of the top surface of the transported wafer measured by the distance measurement unit; A polishing system comprising:

2. 1. A method for controlling wafer transport in a polishing system including a polishing machine that polishes a wafer by a surface plate and a wafer transport machine that transports the wafer into a work hole of a carrier disposed on the surface plate, comprising: After the wafer is transported by the wafer transport device, detecting a height of an upper surface of the transported wafer using a distance measuring unit that measures a distance to an object; estimating a transport state of the wafer based on a height of an upper surface of the wafer; A wafer transport control method comprising:

3. A polishing system including a polishing machine that polishes a wafer by a surface plate, and a wafer transport machine that transports the wafer into a work hole of a carrier arranged on the surface plate, A distance measuring unit that measures a distance to an object; an edge detection unit that detects three or more positions of an edge portion of the work hole using the distance measured by the distance measurement unit; a center calculation unit that calculates an actual center position, which is a center position of the work hole, based on the positions of the three or more edge portions detected by the edge detection unit; a teaching position calculation unit that calculates a teaching position, which is a center position of the work hole calculated based on a relative positional relationship between the base plate and the carrier; The edge detection unit compares a reference value obtained by subtracting a predetermined value from a measurement value indicating a height obtained at a reference detection position previously set as a position estimated to be the substrate portion of the carrier at an outer position of the work hole, with a measurement value indicating a height obtained while moving the distance measurement unit from an edge portion detection position set as a position estimated to be inside the work hole, and detects the edge portion based on a judgment of whether the measurement value indicating the height exceeds the reference value, the predetermined value is a value that sets the reference value to a value that is greater than a measurement value indicating the height obtained at the edge portion detection position and smaller than a measurement value indicating the height obtained at the reference detection position, The wafer transport machine is controlled so that, when transporting the wafer into the work hole, the center position of the wafer to be transported coincides with a target position set by correcting the difference between the teaching position and the actual center position. A polishing system comprising:

4. A method for detecting a position of a work hole of a carrier disposed on a polishing machine base, comprising: a first step of comparing a reference value obtained by subtracting a predetermined value from a measurement value indicating a height obtained at a reference detection position previously set as a position estimated to be the substrate portion of the carrier at the outer position of the work hole with a measurement value indicating a height obtained by measuring the distance to an object while moving a distance measurement unit from an edge detection position set as a position estimated to be the inner side of the work hole, and detecting three or more positions of the edge portion of the work hole based on a judgment of whether the measurement value indicating the height exceeds the reference value; A second step of calculating a center position of the work hole based on the positions of three or more of the edge portions; a third step of detecting a height of an upper surface of the transported wafer using the distance measuring unit after the wafer is transported; a fourth step of estimating a transport state of the wafer based on the height of the upper surface of the wafer; Equipped with the predetermined value is a value that sets the reference value to a value that is greater than a measurement value indicating the height obtained at the edge portion detection position and smaller than a measurement value indicating the height obtained at the reference detection position, In the first step, when detecting the position of the edge portion, three or more edge portion detection positions capable of surrounding the center position of the work hole calculated from the relative positions of the base and the carrier are set, and the three or more positions of the edge portion are detected while moving the distance measurement unit from the edge portion detection positions. A method for detecting a work hole.

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