Workpiece hole detection device and workpiece hole detection method

Abstract

The present invention provides a workpiece hole detection device capable of stably detecting the position of a workpiece hole of a planetary wheel arranged on a fixed plate of a grinder. The workpiece hole detection device for detecting the position of a workpiece hole (14) of a planetary wheel (13) arranged on a lower fixed plate (12) of a grinder (10) comprises: a laser displacement meter (R) for measuring the distance to a test object (T); an edge detection unit (33) for detecting three or more positions of an edge portion of the workpiece hole (14) using the measurement value of the laser displacement meter (R); and a center calculation unit (34) for calculating the center position of the workpiece hole (14) based on the three or more positions of the edge portion detected by the edge detection unit (33).

Description

Technical Field

[0001] The present invention relates to a workpiece hole detection device and a workpiece hole detection method, which detect the position of a workpiece hole of a planetary wheel for holding a wafer ground by a grinder. Background Art

[0002] Conventionally, there is known a workpiece hole detection device that detects the position of a workpiece hole of a planetary wheel that holds a wafer when the wafer is ground by a grinder (for example, see Patent Document 1).

[0003] In the conventional workpiece hole detection device, two cameras arranged to form a predetermined center angle are used to obtain image data, and then the center position of the workpiece hole is detected based on the positions of two points on the edge of the workpiece hole obtained from the image data and the center angle between the cameras.

[0004] Prior art literature

[0005] Patent Literature

[0006] Patent Document 1: Japanese Patent No. 4492155 Summary of the invention

[0007] Problems to be solved by the invention

[0008] However, when the image data is used to detect the center position of the workpiece hole, the quality of the image data varies due to the lighting conditions around the planetary wheel, so that the edge of the workpiece hole cannot be properly detected. In addition, since the image data is used, it is difficult to detect the edge of the workpiece hole when the planetary wheel and the grinding surface (grinding pad, etc.) of the fixed plate mounted on the planetary wheel have the same color.

[0009] The present invention has been made in view of the above problems, and an object thereof is to provide a workpiece hole detection device and a workpiece hole detection method capable of stably detecting the position of a workpiece hole of a planetary wheel arranged on a fixed plate of a grinding machine.

[0010] Technical solutions to solve problems

[0011] In order to achieve the above-mentioned purpose, the workpiece hole detection device of the present invention is used to detect the position of the workpiece hole of the planetary wheel arranged on the fixed plate of the grinding machine, and the workpiece hole detection device includes: a distance measuring unit, which is used to measure the distance to the object to be inspected; an edge detection unit, which uses the measurement value of the distance measuring unit to detect more than three positions of the edge portion of the workpiece hole; and a center calculation unit, which calculates the center position of the workpiece hole based on the more than three positions of the edge portion detected by the edge detection unit.

[0012] Effects of the Invention

[0013] As a result, the workpiece hole position of the planetary wheel disposed on the fixed plate of the grinding machine can be stably detected without being affected by the lighting conditions around the planetary wheel, the color of the planetary wheel, and the like. BRIEF DESCRIPTION OF THE DRAWINGS

[0014] Figure 1 It is a side view schematically showing the overall structure of a grinding system to which the workpiece hole detection device of the first embodiment is applied.

[0015] Figure 2 It is a plan view schematically showing the overall structure of a grinding system to which the workpiece hole detection device according to the first embodiment is applied.

[0016] Figure 3 This is an explanatory diagram showing the measurement principle of the laser displacement meter.

[0017] Figure 4 This is an explanatory diagram showing various detection positions set when performing workpiece hole detection and edge positions to be detected.

[0018] Figure 5 It is an explanatory diagram showing various detection positions set when estimating the wafer transfer state and the movement trajectory of the laser displacement meter.

[0019] Figure 6 This is a diagram showing the measurement values ​​of the laser displacement meter when edge position detection is performed.

[0020] Figure 7 (a) is an explanatory diagram showing the state of a wafer when the wafer is normally transferred. (b) is a diagram showing the measurement value of the laser displacement meter when the wafer is normally transferred.

[0021] Figure 8 (a) is an explanatory diagram showing the state of the wafer when the wafer is riding up. (b) is a first diagram showing the measurement values ​​of the laser displacement meter when the wafer is riding up. (c) is a second diagram showing the measurement values ​​of the laser displacement meter when the wafer is riding up.

[0022] Fig. 9 (a) is an explanatory diagram showing the state of the wafer when the wafer floats. (b) is a diagram showing the measurement value of the laser displacement meter when the wafer floats.

[0023] Fig.10 FIG. 1 is a flow chart showing the wafer transfer control process performed by the main controller of the first embodiment.

[0024] Fig.11 It is an explanatory diagram showing another example of setting the edge detection position.

[0025] Fig.12(a) is an explanatory diagram showing a first modified example of the movement trajectory of the laser displacement meter when estimating the wafer transfer state. (b) is a diagram showing the detection value of the laser displacement meter when the wafer rides up when detecting the height of the wafer top surface along the movement trajectory of the first modified example.

[0026] Fig.13 (a) is an explanatory diagram showing a second modification of the movement trajectory of the laser displacement meter when estimating the wafer transfer state. (b) is a diagram showing the detection value of the laser displacement meter when the wafer rides up when detecting the height of the wafer top surface along the movement trajectory of the second modification. DETAILED DESCRIPTION

[0027] Hereinafter, an implementation of a workpiece hole detection device and a workpiece hole detection method according to the present invention will be described based on a first embodiment shown in the drawings.

[0028] (First embodiment)

[0029] The following is based on Figures 1 to 9 , the structure of the grinding system 1 of the workpiece hole detection device applicable to the first embodiment is described.

[0030] Figure 1 The polishing system 1 shown includes a polishing machine 10 , a wafer conveyor 20 and a main controller 30 .

[0031] The grinding machine 10 is a double-sided grinding device for grinding both the front and back sides of a thin plate-shaped wafer 2 by means of an upper platen 11 and a lower platen 12. Here, the wafer 2 is ground by means of a grinding pad 11a attached to the upper platen 11 and a grinding pad 12a attached to the lower platen 12. Figure 2 As shown, the wafer 2 is accommodated in the workpiece hole 14 of the planetary wheel 13 disposed on the polishing pad 12a, and is held by the planetary wheel 13 and polished.

[0032] The planetary wheel 13 is a disk-shaped thin plate member thinner than the wafer 2. The workpiece hole 14 is a hole that passes through the planetary wheel 13, and its inner diameter is set to be slightly larger than the diameter of the wafer 2. Figure 2 In the illustrated example, one work hole 14 is formed in the planetary wheel 13, but the number of work holes 14 formed in the planetary wheel 13 can be set arbitrarily.

[0033] Furthermore, when the planetary wheel 13 is placed on the grinding pad 12a, its circumferential orientation and position are limited, and its movement trajectory is continuously monitored by, for example, a controller (not shown) of the grinding machine 10. Accordingly, the relative positional relationship between the lower fixed plate 12 and the planetary wheel 13 can be always grasped, and the center position of the workpiece hole 14 can be obtained based on the calculation of the positional relationship. In addition, the center position of the workpiece hole 14 calculated based on the relative positional relationship between the lower fixed plate 12 and the planetary wheel 13 is referred to as the "teaching position α (see Figure 4 )”. The teaching position α is defined by the XY coordinate system of the wafer conveyor 20.

[0034] The wafer conveyor 20 is a robot arm that is driven based on a control instruction from the main controller 30 and automatically conveys the wafers 2 one by one. The wafer conveyor 20 includes a conveying head 21 that can detachably hold the wafer 2 and an arm 22 that moves the conveying head 21 in the horizontal and vertical directions.

[0035] The wafer conveyor 20 holds the wafer 2 taken out from the loading port (not shown) containing a plurality of wafers 2 on the conveying head 21 before grinding the wafer 2. Then, the arm 22 is moved to convey the conveying head 21 to a position above the predetermined work hole 14. Then, the wafer 2 is released from the conveying head 21 and arranged in the work hole 14.

[0036] In addition, after grinding the wafer 2, the wafer conveyor 20 moves the arm 22 to move the conveying head 21 to a position above the predetermined workpiece hole 14. Next, the conveying head 21 is used to hold the wafer 2 in the workpiece hole 14 and remove the wafer 2. Then, the arm 22 is moved to convey the wafer 2 to the unloading port (not shown).

[0037] Furthermore, a laser displacement meter R (distance measuring unit) is mounted on the transfer head 21 of the first embodiment. Figure 3 As shown, the laser displacement meter R is a distance sensor that irradiates a laser beam S1 toward a subject T and measures a distance L to (from) the subject T in a contactless manner based on a reflected light S2 reflected by the subject T.

[0038] When the arm 22 is driven and the transfer head 21 is moved, the laser displacement meter R moves integrally with the transfer head 21. In addition, since the wafer conveyor 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 planetary wheel 13. In addition, even when the laser displacement meter R is being moved by the wafer conveyor 20, the distance to the object T can be measured. In addition, during the measurement by the laser displacement meter R, in order to remove moisture adhering to the object T, air may be sprayed on the object T.

[0039] The main controller 30 outputs a control command to the wafer conveyor 20, controls the conveyance of the wafer 2 through the wafer conveyor 20, and controls the movement of the laser displacement meter R by controlling the movement of the conveying head 21. In addition, the main controller 30 calculates the teaching position α based on the relative positional relationship between the lower plate 12 and the planetary wheel 13, and uses the teaching position α to detect the positions of three or more (four positions in the first embodiment) of the edge portion of the workpiece hole 14. Here, the "edge portion" refers to the inner peripheral edge portion of the workpiece hole 14, and is the boundary between the workpiece hole 14 and the planetary wheel 13. Moreover, the center position of the workpiece hole 14 is calculated based on the position of the detected edge portion. In addition, the position of the edge portion of the workpiece hole 14 and the center position of the workpiece hole 14 are both defined on the XY coordinate system of the wafer conveyor 20. Further, after conveying the wafer 2, the main controller 30 estimates the conveyance state of the wafer based on the upper surface height of the wafer after conveyance.

[0040] 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 34 , a transfer control unit 35 , and a wafer state estimation unit 36 ​​.

[0041] When the information of the relative positional relationship between the lower platen 12 and the planetary wheel 13 is input, the teaching position calculation unit 31 calculates the teaching position α based on the positional relationship information. In addition, the positional relationship information between the lower platen 12 and the planetary wheel 13 is input, for example, from the controller of the grinding machine 10. The information of the teaching position α calculated by the teaching position calculation unit 31 is input to the detection position setting unit 32.

[0042] When the information of 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 workpiece hole 14 based on the teaching position information. In addition, the detection position setting unit 32 inputs the center position of the workpiece hole 14 calculated by the center calculation unit 34 after the wafer 2 is transferred (hereinafter referred to as the "actual center position β (see Figure 5 )”). Then, based on the actual center position information, various detection positions are set when estimating the transfer state of the chip 2. Here, the “detection position” is the moving target point of the laser displacement meter R. The information of the detection position set by the detection position setting unit 32 is input to the transfer control unit 35.

[0043] Here, when detecting the position of the workpiece hole 14, the height of the planetary wheel 13 and four positions of the first edge position P11, the second edge position P13, the third edge position P15 and the fourth edge position P17, which are reference values ​​when detecting the edge of the workpiece hole 14, are detected (see Figure 4 ). Therefore, the detection position setting unit 32 sets the Figure 4The 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 are shown. In addition, the "reference detection position P10" is the moving target point of the laser displacement meter R when detecting the height of the planetary wheel 13. The "first edge detection position P12" is the moving target point of the laser displacement meter R when detecting the first edge position P11. The "second edge detection position P14" is the moving target point of the laser displacement meter R when detecting the second edge position P13. The "third edge detection position P16" is the moving target point of the laser displacement meter R when detecting the third edge position P15. The "fourth edge detection position P18" is the moving target point of the laser displacement meter R when detecting the fourth edge position P17.

[0044] In addition, if Figure 4 As shown in FIG. 1 , 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 the line segment γ connecting these four positions in sequence. That is, when the detection position setting unit 32 sets the edge detection positions, it sets three or more detection positions that can surround the teaching position α.

[0045] Then, the reference detection position P10 is set at a position estimated to be the substrate portion of the planetary gear 13 based on the teaching position α. ​​In addition, the "substrate portion of the planetary gear 13" is a position outside the workpiece hole 14 and is a flat portion where no workpiece hole 14 or dummy hole is formed. In addition, 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 all set at positions estimated to be inside the workpiece hole 14 based on the teaching position α.

[0046] Furthermore, when estimating the transfer state of the wafer 2, in the first embodiment, the height of the planetary wheel 13 and the height of the upper surface of the wafer 2 after transfer are detected as reference values ​​for determining the transfer state of the wafer. Figure 5 The reference detection position P20 and the height detection start position P21 are shown. In addition, the "reference detection position P20" is the moving target point of the laser displacement meter R when detecting the height of the planetary wheel 13. The "height detection start position P21" is the moving target point of the laser displacement meter R when detecting the height of the upper surface of the wafer 2.

[0047] Here, the reference detection position P20 is set at a position estimated to be the substrate portion of the planetary gear 13 based on the actual center position β. Furthermore, the height detection start position P21 is set at a position estimated to be the wafer 2 based on the actual center position β.

[0048] When the measurement value of the laser displacement meter R is input, the edge detection unit 33 detects the positions of three or more (four positions of the first edge position P11 to the fourth edge position P17 in the first embodiment) of the edge portion of the workpiece hole 14 based on the measurement value. The position information of the edge portion detected by the edge detection unit 33 is input to the center calculation unit 34.

[0049] When detecting the edge, the edge detection unit 33 first sets a reference value based on the measurement value obtained by moving the laser displacement meter R to the reference detection position P10. Here, the value obtained by subtracting a predetermined value from the measurement value obtained at the reference detection position P10 is used as the reference value. Next, it is determined whether the measurement value obtained by moving the laser displacement meter R from the first edge detection position P12 along the predetermined trajectory exceeds the reference value. Then, the first edge position P11 is detected based on the movement amount x of the laser displacement meter R when the measurement value exceeds the reference value and the first edge detection position P12 (see Figure 6 ).

[0050] In addition, regarding the second edge position P13, the third edge position P15, and the fourth edge position P17, the edge detection unit 33 performs the same detection as the first edge position P11 each time the laser displacement meter R is moved. That is, the edge detection unit 33 repeatedly performs the operation of detecting the position of the edge portion (the first edge position P11, etc.) while moving the laser displacement meter R from the edge detection position (the first edge detection position P12, etc.) until three or more edge positions (the first edge position P11, etc.) are detected.

[0051] The center calculation unit 34 receives position information of three or more edge portions (four positions of the first edge position P11 to the fourth edge position P17 in the first embodiment) from the edge detection unit 33. Then, the actual center position β is calculated based on the position information of the edge portions. The information of the actual center position β calculated by the center calculation unit 34 is input to the transmission control unit 35. In addition, the actual center position β can be obtained by using the position information of the edge portions at three or more positions and a general equation of a circle.

[0052] The conveyance control unit 35 inputs information of various detection positions (such as the reference detection position P10) from the detection position setting unit 32, and outputs a control command to the wafer conveyor 20 based on the various detection positions. Then, the laser displacement meter R is moved in a predetermined order and at a predetermined time point with the various detection positions as the moving target locations. In addition, after the conveyance control unit 35 moves the laser displacement meter R to a predetermined detection position (such as the first edge position P11), it outputs a control command to the wafer conveyor 20 to move the laser displacement meter R in a predetermined direction.

[0053] After the transfer of the wafer 2, the wafer state estimation unit 36 ​​inputs the measured value of the laser displacement meter R, and estimates the transfer state of the wafer 2 after the transfer is completed based on the measured value. In addition, the transfer state information estimated by the wafer state estimation unit 36 ​​can be input to, for example, the controller of the grinding machine 10, and notified to the operator of the grinding system 1.

[0054] When estimating the wafer transfer state, the wafer state estimation unit 36 ​​first sets a reference range (upper threshold and lower threshold) based on the measurement value obtained when the laser displacement meter R moves to the reference detection position P20. Next, the laser displacement meter R is moved to the height detection start position P21, and it is determined whether the measurement value (the height of the upper surface of the wafer) obtained by moving from the height detection start position P21 along a predetermined trajectory (here, the annular trajectory 3 along the peripheral portion of the wafer 2) exceeds the reference range.

[0055] For example, Figure 7 As shown in (a), when the wafer 2 is normally arranged in the workpiece hole 14, the laser displacement meter R moves along the annular track 3 and the measured value obtained is within the reference range (see Figure 7 (b)) That is, when it is determined that the measured value is within the reference range, the wafer state estimating unit 36 ​​estimates that the wafer 2 is normally arranged.

[0056] On the other hand, Figure 8 As shown in (a), when the wafer 2 is placed on the edge of the workpiece hole 14, the laser displacement meter R moves along the annular track 3 and measures, and the measured value exceeds the reference range (see Figure 8 (b)). In addition, according to the relationship between the setting position of the height detection start position P21 and the placement position of the wafer 2, it is possible to obtain Figure 8 (c) shows the measured value, but in this case, the measured value exceeds the reference range while the laser displacement meter R moves along the circular track 3 and measures. Fig. 9 As shown in (a), even if the wafer 2 is arranged in the workpiece hole 14, when it floats from the polishing pad 12a due to the influence of the polishing liquid and water, the laser displacement meter R moves along the circular track 3 and the measured value exceeds the reference range (see Fig. 9 (b)) Therefore, when it is determined that the obtained measurement value exceeds the reference range, the wafer state estimating unit 36 ​​estimates that the wafer 2 is not normally arranged.

[0057] The following is based on Fig.10 The flowchart shown in FIG. 1 illustrates each step of the wafer transfer control process performed by the main controller 30 of the first embodiment. The wafer transfer control process is repeatedly performed until the wafer 2 is placed in the workpiece holes 14 of all the planetary wheels 13 on the polishing pad 12a.

[0058] In step S1, it is determined whether to start the transfer of the wafer 2. If so (YES (transfer start)), the process proceeds to step S2. If not (NO (not transfer)), the process returns to step S1. The start determination of transfer is performed by, for example, the transfer control unit 35.

[0059] In step S2 (first step), after the start of transfer is determined in step S1, the teaching position calculation unit 31 calculates the teaching position, and the detection position setting unit 32 reads information on the calculated teaching position α, and the process proceeds to step S3.

[0060] In step S3 (first step), after reading 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, fourth edge detection position P18) for detecting the position of the workpiece hole 14 based on the teaching position information, and enters step S4.

[0061] In step S4 (first step), after the detection position is set in step S3, the transfer control unit 35 outputs a control command to the wafer conveyor 20 to move the laser displacement meter R to the reference detection position P10 set in step S3 as the moving target location, and enters step S5.

[0062] In step S5 (first step), after the laser displacement meter R is moved 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 at the position estimated to be the base plate portion of the planetary gear 13, the planetary gear height is detected. And based on the planetary gear height, the reference value when detecting the edge portion of the workpiece hole 14 is set.

[0063] In step S6 (first step), after the planetary wheel height is detected in step S5, a control instruction is output from the conveying control unit 35 to the wafer conveyor 20, and the laser displacement meter R is moved to the first edge detection position P12 set in step S3 as the moving target location, and the process proceeds to step S7.

[0064] In step S7 (first step), after the movement of the laser displacement meter R in step S6, the laser displacement meter R is moved in a predetermined direction, and the distance to the planetary wheel 13 or the polishing pad 12a present below is measured by the laser displacement meter R. Then, based on the measurement value obtained at this time and the reference value set from the planetary wheel height detected in step S5, the edge detection unit 33 detects the first edge position P11, and the process proceeds to step S8.

[0065] In step S8 (first step), after the first edge position P11 is detected in step S7, a control instruction is output from the conveying control unit 35 to the wafer conveyor 20 to move the laser displacement meter R to the second edge detection position P14 set in step S3 as the moving target location, and enter step S9.

[0066] In step S9 (first step), after 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 planetary wheel 13 or the polishing pad 12a located 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 second edge position P13, and the process proceeds to step S10.

[0067] In step S10 (first step), after the second edge position P13 is detected in step S9, a control instruction is output from the conveying control unit 35 to the wafer conveyor 20 to move the laser displacement meter R to the third edge detection position P16 set in step S3 as the moving target location, and enter step S11.

[0068] In step S11 (first step), after 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 planetary wheel 13 or the polishing pad 12a located 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 third edge position P15, and the process proceeds to step S12.

[0069] In step S12 (first step), following the detection of the third edge position P15 in step S11, a control instruction is output from the conveying control unit 35 to the wafer conveyor 20, and the laser displacement meter R is moved to the fourth edge detection position P18 set in step S3 as the moving target location, and step S13 is entered.

[0070] 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 planetary wheel 13 or the polishing pad 12a located 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.

[0071] 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 enters step S15.

[0072] In step S15, following the calculation of the actual center position β in step S14, a control command is output from the transfer control unit 35 to the wafer conveyor 20 to transfer the wafer 2 to the workpiece hole 14, and enter step S16. At this time, 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 is calculated in the transfer control unit 35. Next, the calculated difference (deviation) is corrected with respect to the teaching position α and the target position is set. Then, a control command is output so that the center position of the wafer 2 held on the transfer head 21 coincides with the target position, and the arm unit 22 is controlled so that the wafer 2 is arranged at the center of the workpiece hole 14.

[0073] In step S16 (third step), following the transfer of the wafer 2 in step S15, a control command is output from the transfer control unit 35 to the wafer conveyor 20, and the height of the upper surface of the transferred wafer 2 is detected, and the process proceeds to step S17.

[0074] Here, before detecting the upper surface height of the wafer 2, 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. Next, the transport control unit 35 moves the laser displacement meter R to the reference detection position P20, and causes the laser displacement meter R to measure the distance to the reference detection position P20. In addition, the wafer state estimation unit 36 ​​sets the reference range (upper threshold and lower threshold) based on the measurement value obtained at this time. Then, the transport control unit 35 moves the laser displacement meter R to the height detection start position P21. And, the laser displacement meter R detects the upper surface height of the wafer 2 while moving from the height detection start position P21 along the pre-set circular trajectory 3.

[0075] In step S17 (the fourth step), following the detection of the upper surface height of the chip 2 in step S16, the chip state estimation unit 36 ​​estimates the transfer state of the chip 2 based on the upper surface height of the chip 2 detected in step S16 and the reference range set by the distance to the reference detection position P20, and the process ends.

[0076] Hereinafter, the “workpiece hole position detection function” of the workpiece hole detection device and the workpiece hole detection method of the first embodiment will be described.

[0077] In order to grind the wafer 2 in the grinding system 1 of the first embodiment, the wafer 2 is automatically transferred to the lower platen 12 of the grinder 10 using the wafer conveyor 20. Here, a grinding pad 12a is attached to the lower platen 12 in advance, and a planetary wheel 13 having a workpiece hole 14 is arranged thereon. That is, the wafer conveyor 20 needs to transfer the wafer 2 to the predetermined workpiece hole 14 in a predetermined posture.

[0078] On the other hand, the direction and position of the planetary wheel 13 in the circumferential direction when it is arranged on the grinding pad 12a are specified, and its moving trajectory is constantly monitored. Therefore, the relative positional relationship between the lower fixed plate 12 and the planetary wheel 13 can always be grasped, and the center position of the workpiece hole 14 can also be obtained as the teaching position α. ​​However, due to the clearance between the sun gear and the internal gear of the grinder 10 or the clearance of the planetary wheel, and the increase in clearance caused by wear, the actual center position of the workpiece hole 14 may deviate from the teaching position α. ​​Therefore, when the wafer 2 is transferred using the teaching position α as the target position, the wafer 2 cannot be transferred correctly.

[0079] Therefore, in the wafer conveyor 20 of the first embodiment, in order to identify the position of the workpiece hole 14 where the wafer 2 should be arranged, the positions of the edge portions of the workpiece holes 14 at three or more positions are detected using the laser displacement meter R before the wafer 2 is arranged, and the actual center position β defined on the XY coordinate system of the wafer conveyor 20 is calculated. Then, the difference between the actual center position β and the previously determined teaching position α is corrected to arrange the wafer 2.

[0080] That is, in the transmission control unit 35 of the main controller 30, the execution Fig.10 In step S1 of the flowchart shown, when it is determined that the transfer of the wafer 2 has started, step S2 is executed. Accordingly, the teaching position calculation unit 31 calculates the teaching position α, and the detection position setting unit 32 reads the information of the teaching position α calculated by the teaching position calculation unit 31.

[0081] 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 workpiece hole 14 based on the taught position information.

[0082] 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 where the line segment γ connecting these four positions can surround the teaching position α. ​​In addition, the reference detection position P10 is set at a position of the substrate portion of the planetary wheel 13 estimated based on the teaching position α.

[0083] When the detection position is set by the detection position setting unit 32, steps S4 and S5 are executed to cause the transmission control unit 35 to move the laser displacement meter R with the reference detection position P10 as the moving target location, 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 on the planetary wheel 13 other than the workpiece hole 14. Therefore, the laser displacement meter R can detect the height of the planetary wheel 13.

[0084] When the planetary wheel height is detected, step S6 and step S7 are executed. That is, the transmission control unit 35 moves the laser displacement meter R with the first edge detection position P12 as the moving target location. The laser displacement meter R measures the distance to the object to be inspected (planetary wheel 13 or polishing pad 12a) while moving from the first edge detection position P12. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the previously detected planetary wheel height, and detects the first edge position P11.

[0085] When the first edge position P11 is detected, step S8 and step S9 are executed. That is, the transmission control unit 35 moves the laser displacement meter R with the second edge detection position P14 as the moving target location. The laser displacement meter R measures the distance to the object to be inspected (planet wheel 13 or polishing pad 12a) while moving from the second edge detection position P14. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the previously detected planetary wheel height, and detects the second edge position P13.

[0086] When the second edge position P13 is detected, step S10 and step S11 are executed. That is, the transmission control unit 35 moves the laser displacement meter R with the third edge detection position P16 as the moving target location. The laser displacement meter R measures the distance to the object to be inspected (planet wheel 13 or polishing pad 12a) while moving from the third edge detection position P16. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the previously detected planetary wheel height, and detects the third edge position P15.

[0087] When the third edge position P15 is detected, step S12 and step S13 are executed. That is, the transmission control unit 35 moves the laser displacement meter R with the fourth edge detection position P18 as the moving target location. The laser displacement meter R measures the distance to the object to be inspected (planet wheel 13 or polishing pad 12a) while moving from the fourth edge detection position P18. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the previously detected planetary wheel height, and detects the fourth edge position P17.

[0088] When the edge positions of four positions are detected (first edge position P11, second edge position P13, third edge position P15, fourth edge position P17, and similarly below), step S14 is executed to enable the center calculation unit 34 to calculate the actual center position β using the edge position information of the four positions and the circle equation.

[0089] Then, when the actual center position β is calculated, the transport control unit 35 executes step S15. That is, the transport control unit 35 obtains the difference (deviation) between the teaching position α and the actual center position β, and outputs a control command to make the center position of the wafer 2 coincide with (become consistent with) the target position set by correcting the teaching position α by the difference (deviation), so that the wafer 2 is arranged at the center of the workpiece hole 14.

[0090] As described above, in the first embodiment, the actual center position β is detected based on information on the positions of the edge portions at four positions, which are detected based on the measured values ​​obtained by measuring the distance to the test object T while moving the laser displacement meter R for measuring the distance to the test object T. Therefore, the position of the edge portion of the workpiece hole 14 can be detected without being affected by factors such as the lighting conditions around the detection device and the color of the planetary wheel 13.

[0091] This allows stable detection of the position of the work hole 14 of the planetary wheel 13 disposed on the lower platen 12 of the grinder 10. Furthermore, since the position of the work hole 14 can be stably grasped, the wafer 2 can be accurately disposed at a predetermined position in a predetermined posture.

[0092] Furthermore, the distance to the object T is measured by the laser displacement meter R which measures the distance by the reflected light of the laser. Therefore, since the distance can be measured without contacting the planetary wheel 13 and the polishing pad 12a, the distance L to the object T can be measured with high accuracy while moving. Accordingly, the position of the edge of the workpiece hole 14 can be detected with high accuracy.

[0093] Furthermore, in the first embodiment, the laser displacement meter R is mounted on the conveying head 21 of the wafer conveyor 20 that conveys the wafer 2. Therefore, there is no need to separately provide a mechanism for moving the laser displacement meter R, and the laser displacement meter R can be moved by the wafer conveyor 20 that moves to the vicinity of the workpiece hole 14, so that the laser displacement meter R is moved to an appropriate position, and the position of the edge of the workpiece hole 14 can be detected with high accuracy.

[0094] Furthermore, in the first embodiment, the relative positional relationship between the lower fixed plate 12 and the planetary wheel 13 is monitored, and the teaching position calculation unit 31 calculates the teaching position α based on the relative positional relationship between the lower fixed plate 12 and the planetary wheel 13. Accordingly, the detection position setting unit 32 can set various detection positions when detecting the position of the workpiece hole 14 based on the teaching position α. ​​That is, the position of the edge of the workpiece hole 14 can be detected with the teaching position α as a reference. Therefore, there is no need to make the laser displacement meter R perform extra (unnecessary) movement, and the position detection of the edge of the workpiece hole 14 can be achieved in a short time.

[0095] In addition, 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 similar hereinafter) set by the detection position setting unit 32 are set at positions where the line segment γ connecting these four positions can surround the teaching position α.

[0096] That is, the detection position setting unit 32 sets three or more edge detection positions that can surround the teaching position α when detecting the position of the edge of the workpiece hole 14. Furthermore, the edge detection unit 33 repeatedly detects the position of the edge of the workpiece hole 14 while moving the laser displacement meter R from each edge detection position, and detects the positions of the edge of three or more workpiece holes 14. Figure 4 As shown, the position of the edge of the work hole 14 detected by the edge detection unit 33 is around the teaching position α, 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.

[0097] Furthermore, in the first embodiment, the edge positions are detected at four locations. Therefore, when calculating the actual center position β, four calculation formulas can be set, which can improve the calculation accuracy compared to, for example, detecting the edge positions of the workpiece hole 14 at three locations.

[0098] Hereinafter, the “wafer transfer state estimation function” of the workpiece hole detection device and the workpiece hole detection method according to the first embodiment will be described.

[0099] In the polishing system 1 of the first embodiment, after the wafer 2 is transferred, Fig.10In step S16 of the flowchart shown in the figure, the upper surface height of the wafer 2 is set. 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 conveying control unit 35 drives the wafer conveyor 20, moves the laser displacement meter R to the reference detection position P20, and measures the distance to the reference detection position P20. Here, the reference detection position P20 is the position of the substrate portion estimated as the planetary wheel 13. Therefore, the laser displacement meter R can detect the height of the planetary wheel 13. In addition, at this time, the wafer state estimating unit 36 ​​sets a reference range for estimating the conveying state of the wafer 2 based on the planetary wheel height. Then, the conveying control unit 35 drives the wafer conveyor 20 to move the laser displacement meter R from the height detection start position P21 along the circular track 3. The laser displacement meter R measures the distance to the wafer 2 while moving to detect the upper surface height of the wafer 2.

[0100] After the upper surface height of the wafer 2 is detected by the laser displacement meter R, step S17 is executed, and the wafer state estimating unit 36 ​​compares the detected upper surface height of the wafer 2 with a preset reference range to estimate the conveying state of the wafer 2 .

[0101] As described above, the first embodiment includes the wafer state estimating section 36 that estimates the transport state of the wafer 2 based on the upper surface height of the wafer 2 after transport measured by the laser displacement meter R.

[0102] Based on this, when it is estimated that, for example, the wafer 2 is riding on the edge of the workpiece hole 14 (see Figure 8 (a)), or when the wafer 2 floats from the polishing pad 12a (see Fig. 9 (a)) and the like, when the wafer 2 cannot be arranged at the predetermined position in the predetermined posture, the transmission information is notified to the operator of the polishing system 1, so that the position and posture of the wafer 2 after transmission can be corrected or the polishing process of the wafer 2 can be stopped. That is, it is possible to prevent the polishing process of the wafer 2 that is not arranged at the predetermined position in the predetermined posture from being performed.

[0103] The workpiece hole detection device and the workpiece hole detection method of the present invention are described above based on the first embodiment, but the specific structure is not limited to this embodiment. Design changes and additions are allowed as long as they do not deviate from the main purpose of the invention recorded in each claim for protection.

[0104] In the first embodiment, the edge detection position is set to an example where the line segment γ connecting the edge detection positions of four positions in sequence can surround the teaching position α, but the present invention is not limited to this. As long as the edge position of the workpiece hole 14 at three or more positions can be detected, Fig.11 As shown in FIG. 1 , three or more edge detection positions (in Fig.11 In the example shown, 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'. That is, the edge detection positions can be set arbitrarily.

[0105] In addition, in the first embodiment, an example is shown in which all edge detection positions are set to positions estimated to be inside the workpiece hole 14 based on the teaching position α, but the present invention is not limited to this. The edge detection position can be set outside the workpiece hole 14 (estimated to be the position of the substrate portion of the planetary wheel 13). In addition, when the edge detection position is set to the position inside the workpiece hole 14 and the laser displacement meter R is moved from the inside to the outside of the workpiece hole 14 for measurement, air is blown onto the planetary wheel 13 along with the movement of the laser displacement meter R, making it easy to remove moisture adhering to the edge of the workpiece hole 14, thereby suppressing the occurrence of measurement errors.

[0106] Furthermore, when the teaching position calculation unit 31 and the detection position setting unit 32 are not provided, or the edge detection position is not set, the position of the edge of the workpiece hole 14 can be detected by moving the laser displacement meter R from an arbitrary position to an arbitrary direction while obtaining a measurement value.

[0107] In the first embodiment, an example is shown in which the conveying state of the wafer 2 is estimated based on the measurement value obtained while moving the laser displacement meter R along the annular track 3 along the peripheral edge of the wafer 2. However, the present invention is not limited to this as long as the height of the wafer 2 after conveyance can be detected at a plurality of positions.

[0108] For example, Fig.12 As shown in (a), the conveying state of the wafer 2 can be estimated based on the measurement values ​​obtained by moving the laser displacement meter R along two straight-line tracks (first track 4 and second track 5) orthogonal to the actual center position β. Fig.12 As shown in (b), even if the laser displacement meter R moves along the second trajectory 5 and the measured value obtained is a constant value, when the laser displacement meter R is moved along the first trajectory 4 and the measured value obtained exceeds the upper threshold value, the chip state estimation unit 36 ​​determines that the measured value exceeding the reference range is obtained, and estimates that the chip 2 is not normally configured.

[0109] In addition, if Fig.13As shown in (a), the laser displacement meter R can be moved to the upper position of any six measurement points (6a, 6b, 6c, 6d, 6e, 6f) near the periphery of the wafer 2, and the conveying state of the wafer 2 can be estimated based on the height position of the wafer 2 at each measurement point 6a to 6f. Fig.13 As shown in (b), when any one of the six measurement points 6a to 6f exceeds the reference range, the wafer state estimating unit 36 ​​estimates that the wafer 2 is not normally arranged.

[0110] In the first embodiment, the example of the laser displacement meter R that measures the distance using the reflected light S2 of the laser is shown as the distance measuring unit for measuring the distance to the subject T, but the present invention is not limited to this. For example, a distance measuring device or the like may be used to extend a telescopic measuring rod to the subject T and measure the distance using the length of the rod.

[0111] Furthermore, in the first embodiment, an example is shown in which the wafer 2 is transferred to one work hole 14 formed in the planetary wheel 13, but a plurality of work holes 14 may be formed in the planetary wheel 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 sequentially arranged in the work hole 14 whose actual center position is detected.

[0112] Furthermore, the detection of the actual center position β of the workpiece hole 14 can be performed in a state where the wafer 2 is held by the transfer head 21, or can be performed in a state where the wafer 2 is not held. In the case where the actual center position β is detected in a state where the wafer 2 is held, after the actual center position β is detected, it is not necessary to drive the arm 22 in order to hold the wafer 2. Therefore, an increase in the transfer time of the wafer 2 can be suppressed.

[0113] (Explanation of Symbols)

[0114] 1 Grinding system

[0115] 2 Chips

[0116] 3 Looping tracks

[0117] 4 First track

[0118] 5 Second track

[0119] 6a~6f Measurement points

[0120] 10. Grinder

[0121] 11 Upper plate

[0122] 11a Abrasive pad

[0123] 12 Set the plate

[0124] 12a Abrasive pad

[0125] 13. Star Wheel

[0126] 14 Workpiece hole

[0127] 20 Wafer conveyor

[0128] 21 Transmission Head

[0129] 22 Arm

[0130] 30 Main Controller

[0131] 31 Teaching position calculation unit

[0132] 32 Detection position setting unit

[0133] 33 Edge detection unit

[0134] 34 Central Computing Department

[0135] 35 Transmission Control Unit

[0136] 36 Wafer state estimation unit

[0137] L distance

[0138] P10 reference detection position

[0139] P11 First edge position

[0140] P12, P12′ first edge detection position

[0141] P13 Second edge position

[0142] P14, P14' Second edge detection position

[0143] P15 Third edge position

[0144] P16 Third edge detection position

[0145] P17 Fourth edge position

[0146] P18 Fourth edge detection position

[0147] P20 reference detection position

[0148] P21 Height detection start position

[0149] R Laser displacement meter (distance measurement unit)

[0150] S1 Laser

[0151] S2 Reflected light

[0152] T Subject

[0153] X Movement

[0154] α Teaching position

[0155] β Actual center position

[0156] γ Segment

[0157] Steps S1 to S17.

Claims

1. A workpiece hole detection device for detecting the position of a workpiece hole of a planetary wheel arranged on a fixed plate of a grinding machine, characterized in that: include: a distance measuring unit for measuring the distance to the object; an edge detection unit that detects three or more positions of an edge portion of the workpiece hole using the measurement value of the distance measurement unit; and a center calculation unit that calculates the center position of the workpiece hole based on the three or more positions of the edge portion detected by the edge detection unit, The edge detection unit detects the edge portion by comparing a reference value obtained by subtracting a predetermined value from a measurement value obtained at a reference detection position pre-set as the position of the substrate portion of the planetary wheel estimated to be the outer position of the workpiece hole with a measurement value obtained while moving the distance measuring unit.

2. The workpiece hole detection device according to claim 1, wherein: The distance measuring unit is a laser displacement meter that measures the distance using reflected light of laser light.

3. The workpiece hole detection device according to claim 1, wherein: A teaching position calculation unit is included: the teaching position calculation unit calculates the center position of the workpiece hole based on the relative position between the fixed plate and the planetary wheel.

4. The workpiece hole detection device according to claim 2, wherein: A teaching position calculation unit is included: the teaching position calculation unit calculates the center position of the workpiece hole based on the relative position between the fixed plate and the planetary wheel.

5. The workpiece hole detection device according to any one of claims 1 to 4, wherein: A wafer state estimating unit is included, which estimates the transfer state of the wafer based on the upper surface height of the wafer after transfer measured by the distance measuring unit.

6. The workpiece hole detection device according to any one of claims 1 to 4, wherein: The distance measuring unit is installed on a wafer conveyor that conveys the wafer into the workpiece hole.

7. The workpiece hole detection device according to claim 5, wherein: The distance measuring unit is installed on a wafer conveyor that conveys the wafer into the workpiece hole.

8. A workpiece hole detection method for detecting the position of a workpiece hole of a planetary wheel disposed on a fixed plate of a grinding machine, characterized in that: It includes the following steps: A first step of detecting three or more positions of the edge portion of the workpiece hole by comparing a reference value obtained by measuring the distance to the object while moving the distance measuring unit, the reference value being a value obtained by subtracting a predetermined value from a measurement value obtained at a reference detection position previously set as a position of the substrate portion of the planetary wheel estimated to be an outer position of the workpiece hole; and A second step is to calculate the center position of the workpiece hole based on the positions of three or more positions of the edge portion.

9. The workpiece hole detection method according to claim 8, wherein: In the first step, when detecting the position of the edge portion, at least three edge portion detection positions that can surround the center position of the workpiece hole are set, and while moving the distance measuring unit from the edge portion detection positions, at least three positions of the edge portion are detected. The center position of the workpiece hole is a position calculated based on the relative position between the fixed plate and the planetary wheel.

10. The workpiece hole detection method according to claim 8 or 9, wherein: The following steps are required: After the wafer is transferred, a third step of using the distance measuring unit to detect the height of the upper surface of the transferred wafer; and A fourth step is to estimate the transfer state of the wafer based on the upper surface height of the wafer.

Images