JP2021102245A - Workpiece hole detection device and workpiece hole detection method - Google Patents

Abstract

To provide a workpiece hole detection device which can stably detect a position of a workpiece hole of a carrier arranged on a surface plate of a polishing machine.SOLUTION: A workpiece hole detection device detects a position of a workpiece hole 14 of a carrier 13 arranged on a lower surface plate 12 of a polishing machine 10. The workpiece hole detection device includes: a laser displacement gauge R which measures a distance to an object; an edge detection section 33 which uses a measured value of the laser displacement gauge R and detects three or more positions of edge sections of the workpiece hole 14; and a center arithmetic section 34 which calculates a center position of the workpiece hole 14 on the basis of the three or more positions of the edge sections detected by the edge detection section 33.SELECTED DRAWING: Figure 1

Description

The present invention relates to a work hole detection device and a work hole detection method for detecting the position of a work hole of a carrier holding a wafer to be polished by a polishing machine.

Conventionally, a work hole detection device that detects the position of a work hole of a carrier that holds a wafer when polishing a wafer with a polishing machine has been known (see, for example, Patent Document 1). In the conventional work hole detection device, image data is acquired by two cameras installed so as to form a predetermined central angle. Then, the center position of the work hole is detected based on the positions of the two points on the edge portion of the work hole obtained from this image data and the central angle between the cameras.

Patent No. 4492155

However, when the image data is used when detecting the center position of the work hole, it is considered that the quality of the image data varies due to the influence of the lighting condition around the carrier, and the edge portion of the work hole cannot be detected appropriately. In addition, since image data is used, it is difficult to detect the edge of the work hole when the color of the carrier and the polished surface (polishing pad, etc.) of the surface plate on which this carrier is placed are similar. Problems occur.

The present invention has focused on the above problems, and provides a work hole detection device and a work hole detection method capable of stably detecting the work hole position of a carrier arranged on a surface plate of a polishing machine. The purpose is to do.

In order to achieve the above object, the present invention is a work hole detection device that detects the position of a work hole of a carrier arranged on a surface plate of a grinding machine, and has a distance measuring unit that measures a distance to an object. Based on the edge detection unit that detects the positions of the edge portions of the work hole at three or more locations using the measured values of the distance measurement unit, and the positions of the edge portions at three or more locations detected by the edge detection unit. , A central calculation unit for calculating the central position of the work hole.

As a result, the work hole position of the carrier arranged on the surface plate of the polishing machine can be stably detected without being affected by the illumination state around the carrier, the color of the carrier, and the like.

It is a side view which shows schematic the whole structure of the polishing system to which the work hole detection apparatus of Example 1 was applied. FIG. 5 is a plan view schematically showing an overall configuration of a polishing system to which the work hole detection device of the first embodiment is applied. It is explanatory drawing which shows the measurement principle of a laser displacement meter. It is explanatory drawing which shows the various detection positions set at the time of work hole detection, and the detected edge position. It is explanatory drawing which shows the various detection positions set at the time of estimating a wafer transfer state, and the movement locus of a laser displacement meter. It is a figure which shows the measured value of the laser displacement meter at the time of edge position detection. (A) It is explanatory drawing which shows the wafer state at the time of normal wafer transfer. (B) It is a figure which shows the measured value of the laser displacement meter at the time of normal wafer transfer. (A) It is explanatory drawing which shows the wafer state at the time of wafer loading. (B) FIG. 1 is a diagram showing a measured value of a laser displacement meter when the wafer is mounted. (C) FIG. 2 is a diagram showing a measured value of a laser displacement meter when the wafer is mounted. (A) It is explanatory drawing which shows the wafer state at the time of the wafer floating. (B) It is a figure which shows the measured value of the laser displacement meter at the time of floating a wafer. It is a flowchart which shows the wafer transfer control processing executed by the main controller of Example 1. FIG. It is explanatory drawing which shows the other setting example of the edge part detection position. (A) It is explanatory drawing which shows the 1st modification of the movement locus of a laser displacement meter at the time of estimating a wafer transfer state. (B) It is a figure which shows the detection value of the laser displacement meter at the time of the wafer landing at the time of detecting the height of the upper surface of the wafer along the movement locus of the 1st modification. (A) It is explanatory drawing which shows the 2nd modification of the movement locus of the laser displacement meter at the time of estimating the wafer transfer state. (B) It is a figure which shows the detection value of the laser displacement meter at the time of running on a wafer when the height of the upper surface of a wafer is detected along the movement locus of the 2nd modification.

Hereinafter, a mode for carrying out the work hole detection device and the work hole detection method of the present invention will be described with reference to Example 1 shown in the drawings.

(Example 1)
Hereinafter, the configuration of the polishing system 1 to which the work hole detection device of the first embodiment is applied will be described with reference to FIGS. 1 to 9.

The polishing system 1 shown in FIG. 1 includes a polishing machine 10, a wafer transfer machine 20, and a main controller 30.

The polishing machine 10 is a double-sided polishing machine that polishes both the front and back surfaces of the thin plate-shaped wafer 2 by the upper surface plate 11 and the lower surface plate 12. Here, the wafer 2 is polished by the polishing pad 11a attached to the upper surface plate 11 and the polishing pad 12a attached to the lower surface plate 12. Further, as shown in FIG. 2, the wafer 2 is housed in the work hole 14 of the carrier 13 arranged on the polishing pad 12a, held by the carrier 13 and polished.

The carrier 13 is a disk-shaped thin plate member thinner than the wafer 2. The work hole 14 is a hole penetrating the carrier 13, and is set to an inner diameter dimension 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 arbitrarily set.

Further, when the carrier 13 is arranged on the polishing pad 12a, the orientation and position in the circumferential direction are defined, and the movement locus is constantly monitored by, for example, a controller (not shown) of the polishing machine 10. As a result, the relative positional relationship between the lower platen 12 and the carrier 13 can always be 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 platen 12 and the carrier 13 is hereinafter referred to as "teaching position α (see FIG. 4)". This teaching position α is defined by the XY coordinate system of the wafer transfer machine 20.

The wafer transfer machine 20 is a robot arm that is driven based on a control command from the main controller 30 and automatically transfers wafers 2 one by one. The wafer transfer machine 20 includes a transfer head 21 that holds the wafer 2 detachably and detachably, and an arm portion 22 that moves the transfer head 21 in the horizontal direction and the vertical direction.

The wafer transfer machine 20 holds the wafer 2 taken out from the load port (not shown) accommodating a large number of wafers 2 by the transfer head 21 prior to the polishing process of the wafer 2. Next, the arm portion 22 is moved to convey the transfer head 21 to a position above the predetermined work hole 14. Then, the wafer 2 is released from the transfer head 21 and placed in the work hole 14.

Further, after the wafer 2 is polished, the wafer transfer machine 20 moves the arm portion 22 to move the transfer head 21 to a position above a predetermined work hole 14. Subsequently, the transfer head 21 holds the wafer 2 in the work hole 14 and takes out the wafer 2. Then, the arm portion 22 is moved to convey the wafer 2 to an unload port (not shown).

Further, the transport head 21 of the first embodiment is equipped with a laser displacement meter R (distance measuring unit). As shown in FIG. 3, the laser displacement meter R irradiates the object T with the laser beam S1 and measures the distance L to the object T in a non-contact manner based on the reflected light S2 reflected by the object T. It is a distance sensor.

When the laser displacement meter R drives the arm portion 22 to move the transport head 21, the laser displacement meter R moves integrally with the transport head 21. Further, since the wafer transfer machine 20 can be moved while keeping the height position of the laser displacement meter R constant, the laser displacement meter R can measure the thickness of the carrier 13. Further, the laser displacement meter R can measure the distance to the object T even while the wafer transfer machine 20 is moving. During the measurement of the laser displacement meter R, air may be injected onto the object T in order to remove the moisture adhering to the object T.

The main controller 30 outputs a control command to the wafer transfer machine 20, controls the transfer of the wafer 2 by the wafer transfer machine 20, and also controls the movement of the laser displacement meter R due to the movement of the transfer head 21. Further, the main controller 30 calculates the teaching position α based on the relative positional relationship between the lower platen 12 and the carrier 13, and uses this teaching position α to position the edge portion of the work hole 14 at three or more locations ( In Example 1, four places) are detected. Here, the "edge portion" is an inner peripheral edge portion of the work hole 14, and is a boundary between the work hole 14 and the carrier 13. Then, the center position of the work hole 14 is calculated based on the detected position of the edge portion. The position of the edge portion of the work hole 14 and the center position of the work hole 14 are both defined by the XY coordinate system of the wafer transfer machine 20. Further, after the wafer 2 is transferred, the main controller 30 estimates the transferred state of the wafer based on the height of the upper surface of the transferred wafer.

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. There is.

When the information on the relative positional relationship between the lower platen 12 and the carrier 13 is input, the teaching position calculation unit 31 calculates the 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. The information of the teaching position α calculated by the teaching position calculation unit 31 is input to the detection position setting unit 32.

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 work hole 14 based on the teaching position information. Further, after the wafer 2 is transferred, the detection position setting unit 32 is input with information on the center position of the work hole 14 calculated by the center calculation unit 34 (hereinafter, referred to as “actual center position β (see FIG. 5)”). To. Then, based on this actual center position information, various detection positions when estimating the transfer state of the wafer 2 are set. Here, the "detection position" is a movement 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 transport control unit 35.

Here, when the position of the work hole 14 is detected, the height of the carrier 13 which is a reference value when detecting the edge portion of the work hole 14 and the first edge position P11, the second edge position P13, and the third edge position Four positions (see FIG. 4) of P15 and the fourth edge position P17 are detected. Therefore, the detection position setting unit 32 includes the reference detection position P10, the first edge portion detection position P12, the second edge portion detection position P14, the third edge portion detection position P16, and the fourth edge portion shown in FIG. The detection position P18 is set. The "reference detection position P10" is a movement target point of the laser displacement meter R when detecting the height of the carrier 13. The “first edge portion detection position P12” is a movement target point of the laser displacement meter R when detecting the first edge position P11. The “second edge portion detection position P14” is a movement target point of the laser displacement meter R when detecting the second edge position P13. The “third edge portion detection position P16” is a movement target point of the laser displacement meter R when detecting the third edge position P15. The “fourth edge portion detection position P18” is a movement target point of the laser displacement meter R when detecting the fourth edge position P17.

Further, the first edge portion detection position P12, the second edge portion detection position P14, the third edge portion detection position P16, and the fourth edge portion detection position P18 connect these four positions in order as shown in FIG. It is set to a position where the teaching position α can be surrounded by the line segment γ. That is, when setting the edge portion detection position, the detection position setting unit 32 sets three or more detection positions that can surround the teaching position α.

Then, the reference detection position P10 is set to a position estimated to be the substrate portion of the carrier 13 based on the teaching position α. The "board portion of the carrier 13" is a flat portion that is located outside the work hole 14 and in which no work hole 14 or a waste hole is formed. Further, the first edge portion detection position P12, the second edge portion detection position P14, the third edge portion detection position P16, and the fourth edge portion detection position P18 are all inside the work hole 14 based on the teaching position α. It is set to the position estimated to be.

Further, when estimating the transferred state of the wafer 2, in the first embodiment, the height of the carrier 13 which is a reference value when determining the transferred state of the wafer and the height of the upper surface of the transferred wafer 2 are detected. Therefore, the detection position setting unit 32 sets the reference detection position P20 and the height detection start position P21 shown in FIG. 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 height of the upper surface of the wafer 2.

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

When the measured value of the laser displacement meter R is input, the edge detection unit 33 positions the edge portion of the work hole 14 at three or more locations (first edge positions P11 to 4 in the first embodiment) based on the measured value. (Four points at edge position P17) are detected. The position information of the edge portion detected by the edge detection unit 33 is input to the center calculation unit 34.

When detecting the edge portion, the edge detection unit 33 first sets the reference value based on the measured value obtained by moving the laser displacement meter R to the reference detection position P10. Here, a value obtained by subtracting a predetermined value from the measured value obtained at the reference detection position P10 is used as the reference value. Subsequently, it is determined whether or not the measured value obtained while moving the laser displacement meter R from the first edge portion detection position P12 along a predetermined locus 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 measured value exceeds the reference value and the first edge portion detection position P12 (see FIG. 6).

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 detects the position of the edge portion (first edge position P11, etc.) while moving the laser displacement meter R from the edge portion detection position (first edge portion detection position P12, etc.). The position of the portion (first edge position P11, etc.) is repeated until it is detected at three or more locations.

The central calculation unit 34 inputs the position information of the edge portions at three or more locations (four locations of the first edge position P11 to the fourth edge position P17 in the first embodiment) from the edge detection unit 33. Then, the real center position β is calculated based on the position information of the edge portion. The information of the actual center position β calculated by the center calculation unit 34 is input to the transfer control unit 35. The real center position β can be obtained by using the position information of three or more edge portions and a general circle equation.

The transfer 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 transfer machine 20 based on the various detection positions. Then, the laser displacement meter R is moved with various detection positions as movement target points in a predetermined order and timing. Further, the transfer control unit 35 moves the laser displacement meter R to a predetermined detection position (first edge position P11, etc.), then outputs a control command to the wafer transfer machine 20, and laser displacements in a predetermined direction. Move the total R.

After the wafer 2 is transferred, the wafer state estimation unit 36 inputs the measured value of the laser displacement meter R, and estimates the transferred state of the transferred wafer 2 based on the measured value. The transfer state information estimated by the wafer state estimation unit 36 may be input to, for example, a controller of the polishing machine 10 or the like, and may be notified to an operator or the like of the polishing system 1.

When estimating the wafer transfer state, the wafer state estimation unit 36 first estimates the reference range (upper threshold value and lower threshold value) based on the measured values obtained when the laser displacement meter R is moved to the reference detection position P20. To set. Subsequently, the laser displacement meter R is moved to the height detection start position P21, and from this height detection start position P21 to a predetermined predetermined locus (here, the annular locus 3 along the peripheral edge of the wafer 2). It is determined whether or not the measured value (height of the upper surface of the wafer) obtained while moving along the reference range exceeds the reference range.

For example, as shown in FIG. 7A, when the wafer 2 is normally arranged in the work hole 14, the measured value obtained while the laser displacement meter R moves along the annular locus 3 is within the reference range. It fits inside (see FIG. 7 (b)). That is, when the wafer state estimation unit 36 determines that the measured value is within the reference range, it estimates that the wafer 2 is normally arranged.

On the other hand, as shown in FIG. 8A, when the wafer 2 rides on the edge portion of the work hole 14, the measured value is in the middle of the measurement while the laser displacement meter R is moving along the annular locus 3. Exceeds the reference range (see FIG. 8B). Depending on the relationship between the set position of the height detection start position P21 and the landing position of the wafer 2, the measured value shown in FIG. 8C can be obtained, but even in this case, the laser displacement meter R is annular. The measured value exceeds the reference range during the measurement while moving along the locus 3. Further, as shown in FIG. 9A, the laser displacement meter R has an annular locus even when the wafer 2 is arranged in the work hole 14 and is lifted from the polishing pad 12a due to the influence of slurry, water, or the like. The measured value exceeds the reference range during the measurement while moving along No. 3 (see FIG. 9B). Therefore, when the wafer state estimation unit 36 determines that the measured value exceeding the reference range has been obtained, it estimates that the wafer 2 is not normally arranged.

Hereinafter, each step of the wafer transfer control process executed by the main controller 30 of the first embodiment will be described with reference to the flowchart shown in FIG. This wafer transfer control process is repeatedly executed until the wafer 2 is arranged in the work holes 14 of all the carriers 13 on the polishing pad 12a.

In step S1, it is determined whether or not to start the transfer of the wafer 2. If YES (start of transportation), the process proceeds to step S2. If NO (not conveyed), step S1 is repeated. The transfer start determination is made by, for example, the transfer control unit 35.

In step S2 (first step), following the determination that the transfer is started in step S1, the teaching position calculation unit 31 calculates the teaching position, and the detection position setting unit 32 outputs the calculated teaching position α information. Read and proceed to step S3.

In step S3 (first step), following the reading of the teaching position information in step S2, various detection positions when the detection position setting unit 32 detects the position of the work hole 14 based on the teaching position information. (Reference detection position P10, first edge detection position P12, second edge detection position P14, third edge detection position P16, fourth edge detection position P18) are set, and the process proceeds to step S4.

In step S4 (first step), following the setting of the detection position in step S3, the transfer control unit 35 outputs a control command to the wafer transfer machine 20, and the reference detection position P10 set in step S3 is set as the movement target point. The laser displacement meter R is moved as described above, and the process proceeds to step S5.

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 at a position presumed 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.

In step S6 (first step), following the detection of the carrier height in step S5, the transfer control unit 35 outputs a control command to the wafer transfer machine 20, and the first edge portion detection position P12 set in step S3. The laser displacement meter R is moved with the moving target point, and the process proceeds to step S7.

In step S7 (first step), following the movement of the laser displacement meter R in step S6, the carrier 13 or polishing existing below by the laser displacement meter R while moving the laser displacement meter R in a predetermined direction. Measure the distance to the pad 12a. Then, the edge detection unit 33 detects the first edge position P11 based on the measured value obtained at this time and the reference value set from the carrier height detected in step S5, and proceeds to step S8.

In step S8 (first step), following the detection of the first edge position P11 in step S7, the transfer control unit 35 outputs a control command to the wafer transfer machine 20, and the second edge portion detection set in step S3 is performed. The laser displacement meter R is moved with the position P14 as the movement target point, and the process proceeds to step S9.

In step S9 (first step), following the movement of the laser displacement meter R in step S8, the carrier 13 or polishing existing below by the laser displacement meter R while moving the laser displacement meter R in a predetermined direction. Measure the distance to the pad 12a. Then, based on the measured 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 proceeds to step S10.

In step S10 (first step), following the detection of the second edge position P13 in step S9, the transfer control unit 35 outputs a control command to the wafer transfer machine 20, and the third edge portion detection set in step S3 is performed. The laser displacement meter R is moved with the position P16 as the movement target point, and the process proceeds to step S11.

In step S11 (first step), following the movement of the laser displacement meter R in step S10, the carrier 13 or polishing existing below by the laser displacement meter R while moving the laser displacement meter R in a predetermined direction. Measure the distance to the pad 12a. Then, based on the measured 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 proceeds to step S12.

In step S12 (first step), following the detection of the third edge position P15 in step S11, the transfer control unit 35 outputs a control command to the wafer transfer machine 20, and the fourth edge portion detection set in step S3 is performed. The laser displacement meter R is moved with the position P18 as the movement target point, and the process proceeds to step S13.

In step S13 (first step), following the movement of the laser displacement meter R in step S12, the carrier 13 or polishing existing below by the laser displacement meter R while moving the laser displacement meter R in a predetermined direction. Measure the distance to the pad 12a. Then, based on the measured 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 proceeds to step S14.

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

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, transfers the wafer 2 into the work hole 14, and proceeds to step S16. At this time, the transport control unit 35 obtains the difference (deviation amount) 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. Subsequently, the calculated difference (deviation amount) is corrected with respect to the teaching position α, and the target position is set. Then, a control command for matching the center position of the wafer 2 held by the transfer head 21 with the target position is output, and the arm portion 22 is controlled so that the wafer 2 is arranged at the center of the work hole 14.

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, detects the height of the upper surface of the transferred wafer 2, and steps. Proceed to S17.

Here, prior to detecting the height of the upper surface of the wafer 2, the detection position setting unit 32 first sets the reference detection position P20 and the height detection start position P21 based on the actual center position β. Subsequently, the transfer 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 threshold value and lower threshold value) based on the measured values obtained at this time. After that, the transfer control unit 35 moves the laser displacement meter R to the height detection start position P21. Then, the laser displacement meter R detects the height of the upper surface of the wafer 2 while moving along the annular locus 3 set in advance from the height detection start position P21.

In step S17 (fourth step), following the detection of the top surface height of the wafer 2 in step S16, the reference range set from the top surface height of the wafer 2 detected in step S16 and the distance to the reference detection position P20. Based on the above, the wafer state estimation unit 36 estimates the transfer state of the wafer 2, and proceeds to the end.

Hereinafter, the “workhole position detection action” of the workhole detection device and the workhole detection method of the first embodiment will be described.

In order to polish the wafer 2 in the polishing system 1 of the first embodiment, the wafer 2 is automatically transferred onto the lower platen 12 of the polishing machine 10 by using the wafer transfer 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 arranged on the polishing pad 12a. That is, the wafer transfer machine 20 needs to transfer the wafer 2 into the determined work hole 14 in a determined posture.

On the other hand, when the carrier 13 is arranged on the polishing pad 12a, the orientation and position in the circumferential direction are defined, and the movement locus is constantly monitored. Therefore, the relative positional relationship between the lower platen 12 and the carrier 13 is always grasped, and the center position of the work hole 14 is also obtained as the teaching position α. However, the actual center position of the work hole 14 may deviate from the teaching position α due to the backlash of the sun gear and the internal gear of the polishing machine 10, the backlash of the carrier, and the increase of the backlash due to wear. is there. Therefore, when the wafer 2 is conveyed with the teaching position α as the target position, the wafer 2 may not be appropriately conveyed.

Therefore, in the wafer transfer machine 20 of the first embodiment, in order to recognize the position of the work hole 14 in which the wafer 2 should be arranged, the edge of the work hole 14 at three or more places is used by using the laser displacement meter R before the wafer 2 is arranged. The position of the unit is detected, and the actual center position β defined by the XY coordinate system of the wafer transfer machine 20 is calculated. Then, the wafer 2 is arranged by correcting the difference between the actual center position β and the teaching position α obtained in advance.

That is, the transfer control unit 35 of the main controller 30 executes step S1 of the flowchart shown in FIG. 10, and if it is determined that the transfer of the wafer 2 is 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 of the teaching position α calculated by the teaching position calculation unit 31.

Subsequently, the detection position setting unit 32 executes step S3, and based on the teaching position information, various detection positions (reference detection position P10, first edge portion detection position P12) when detecting the position of the work hole 14 , The second edge portion detection position P14, the third edge portion detection position P16, and the fourth edge portion detection position P18) are set.

Here, the first edge portion detection position P12, the second edge portion detection position P14, the third edge portion detection position P16, and the fourth edge portion detection position P18 are the teaching positions α by the line segment γ connecting these four positions. It is set to a position where it can surround. Further, the reference detection position P10 is set to a position presumed to be the substrate portion of the carrier 13 based on the teaching position α.

When the detection position is set by the detection position setting unit 32, steps S4 and S5 are executed, and the transfer control unit 35 moves the laser displacement meter R with the reference detection position P10 as the movement target point, and the laser displacement meter R moves the laser displacement meter R. The distance to the reference detection position P10 is measured. Here, the reference detection position P10 is a position where the work hole 14 of the carrier 13 is not present. Therefore, the laser displacement meter R can detect the height of the carrier 13.

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

When 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 with the second edge portion detection position P14 as the movement target point. The laser displacement meter R measures the distance from the second edge portion detection position P14 to the object (carrier 13 or polishing pad 12a) while moving. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the carrier height detected in advance, and detects the second edge position P13.

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 with the third edge portion detection position P16 as the movement target point. The laser displacement meter R measures the distance from the third edge portion detection position P16 to the object (carrier 13 or polishing pad 12a) while moving. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the carrier height detected in advance, and detects the third edge position P15.

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 with the fourth edge portion detection position P18 as the movement target point. The laser displacement meter R measures the distance from the fourth edge portion detection position P18 to the object (carrier 13 or polishing pad 12a) while moving. The edge detection unit 33 compares the measured value obtained at this time with the reference value obtained from the carrier height detected in advance, and detects the fourth edge position P17.

When the four edge positions (first edge position P11, second edge position P13, third edge position P15, fourth edge position P17, and the same applies hereinafter) are detected, step S14 is executed, and the central calculation unit 34 determines. The real center position β is calculated using the information on the four edge positions and the circle equations.

Then, when the actual center position β is calculated, the transport control unit 35 executes step S15. That is, the transfer control unit 35 obtains the difference (deviation amount) between the teaching position α and the actual center position β, corrects the teaching position α based on this difference (deviation amount), and sets the center position of the wafer 2 at the target position. Is output, and the wafer 2 is placed in the center of the work hole 14.

As described above, in the first embodiment, the actual center position β is detected based on the information on the positions of the four edge portions, and the positions of the four edge portions are the lasers that measure the distance to the object T. The distance to the object T is measured while moving the displacement meter R, and detection is performed based on the measured value obtained. Therefore, the position of the edge portion of the work hole 14 can be detected without being affected by the lighting state around the detection device, the color of the carrier 13, and the like.

As a result, the position of the work hole 14 of the carrier 13 arranged on the lower platen 12 of the polishing machine 10 can be stably detected. Since the position of the work hole 14 can be stably grasped, the wafer 2 can be accurately arranged at a determined position and in a determined posture.

Further, the distance to the object T is measured by a laser displacement meter R that measures this distance by the reflected light of the laser beam. Therefore, since the distance can be measured without contacting the carrier 13 or the polishing pad 12a, it is possible to measure with high accuracy while moving the distance L to the object T. As a result, the position of the edge portion of the work hole 14 can be detected with high accuracy.

Further, in the first embodiment, the laser displacement meter R is mounted on the transfer head 21 of the wafer transfer machine 20 that conveys the wafer 2. Therefore, the laser displacement meter R can be moved by using the wafer carrier 20 that moves to the vicinity of the work hole 14, and the laser displacement can be moved to an appropriate position without separately providing a mechanism for moving the laser displacement meter R. The meter R can be moved to detect the position of the edge portion of the work hole 14 with high accuracy.

Further, 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 teaches based on the relative positional relationship between the lower platen 12 and the carrier 13. Calculate the position α. As a result, the detection position setting unit 32 can set various detection positions when detecting the position of the work hole 14 based on the teaching position α. That is, the position of the edge portion of the work hole 14 can be detected with the teaching position α as a guide. Therefore, it is not necessary to move the laser displacement meter R unnecessarily, and the position of the edge portion of the work hole 14 can be detected in a short time.

Moreover, the edge portion detection position set by the detection position setting unit 32 (first edge portion detection position P12, second edge portion detection position P14, third edge portion detection position P16, fourth edge portion detection position P18, and so on. ) Is set at a position where the teaching position α can be surrounded by the line segment γ connecting these four positions.

That is, when detecting the position of the edge portion of the work hole 14, the detection position setting unit 32 sets three or more edge portion detection positions capable of surrounding the teaching position α. Then, the edge detection unit 33 repeatedly detects the position of the edge portion of the work hole 14 while moving the laser displacement meter R from each edge portion detection position, and detects the positions of the edge portions of the work hole 14 at three or more locations. To do. Therefore, as shown in FIG. 4, the position of the edge portion of the work hole 14 detected by the edge detection unit 33 becomes a position surrounding the teaching position α, and the actual center position is based on the position of the edge portion of the work hole 14. It is possible to improve the calculation accuracy when calculating β.

Moreover, in the first embodiment, the positions of the four edge portions are detected. Therefore, when calculating the actual center position β, it is possible to formulate four calculation formulas, and the calculation accuracy can be improved as compared with the case where, for example, the positions of the edge portions of the work hole 14 are detected at three places. ..

Hereinafter, the “wafer transfer state estimation action” of the work hole detection device and the work hole detection method of the first embodiment will be described.

In the polishing system 1 of the first embodiment, after the wafer 2 is conveyed, step S16 in the flowchart shown in FIG. 10 is executed to set the height of the upper surface 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 transfer control unit 35 drives the wafer transfer machine 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 a position estimated to be the substrate portion 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 transfer state of the wafer 2 based on the carrier height. Then, the transfer control unit 35 drives the wafer transfer machine 20 to move the laser displacement meter R from the height detection start position P21 along the annular locus 3. The laser displacement meter R measures the distance to the wafer 2 while moving, and detects the height of the upper surface of the wafer 2.

When the height of the upper surface 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 upper surface height of the wafer 2 with the preset reference range, and the wafer 2 Estimate the transport state of.

As described above, in the first embodiment, the wafer state estimation unit 36 that estimates the transferred state of the wafer 2 based on the height of the upper surface of the transferred wafer 2 measured by the laser displacement meter R is provided.

As a result, when the wafer 2 rides on the edge portion of the work hole 14 (see FIG. 8A) or when the wafer 2 is lifted from the polishing pad 12a (see FIG. 9A), the wafer 2 can be moved. When it is estimated that the wafers are not arranged at the determined positions in the determined positions, the position and orientation of the transferred wafer 2 can be corrected by notifying the operator of the polishing system 1 of the transfer information. , The polishing process of the wafer 2 can be stopped. That is, it is possible to prevent the wafer 2 which is not arranged at a predetermined position and in a predetermined posture from being polished.

Although the work hole detection device and the work hole detection method of the present invention have been described above based on the first embodiment, the specific configuration is not limited to this embodiment, and each claim is within the scope of the claims. Design changes and additions are permitted as long as they do not deviate from the gist of the invention.

In the first embodiment, an example is shown in which the edge portion detection position is set at a position where the teaching position α can be surrounded by the line segment γ connecting the four edge portion detection positions in order, but the present invention is not limited to this. Since it is only necessary to detect the positions of the edge portions of the work holes 14 at three or more locations, as shown in FIG. 11, the edge portion detection positions at three or more locations (in the example shown in FIG. 11) are located at positions not surrounding the teaching position α. The first edge portion detection position P12', the second edge portion detection position P14', the third edge portion detection position P16', and the fourth edge portion detection position P18') may be set. That is, the edge portion detection position can be arbitrarily set.

Further, in the first embodiment, an example is shown in which all the edge portion detection positions are set to positions estimated to be inside the work hole 14 based on the teaching position α, but the present invention is not limited to this. The edge portion detection position may be set on the outside of the work hole 14 (position presumed to be the substrate portion of the carrier 13). When the edge detection position is set to the position inside the work hole 14 and the laser displacement meter R is moved from the inside to the outside of the work hole 14 for measurement, the carrier is moved along with the movement of the laser displacement meter R. By blowing air on the work hole 14, the moisture adhering to the edge portion of the work hole 14 can be easily removed, and the occurrence of measurement error can be suppressed.

Further, the teaching position calculation unit 31 and the detection position setting unit 32 are not provided, and the measured value obtained while moving the laser displacement meter R from an arbitrary position to an arbitrary direction without setting the edge portion detection position. May be used to detect the position of the edge portion of the work hole 14.

Further, in Example 1, an example is shown in which the transport state of the wafer 2 is estimated based on the measured value obtained by moving the laser displacement meter R along the annular locus 3 along the peripheral edge of the wafer 2. However, the height of the transferred wafer 2 is not limited to this as long as it can be detected at a plurality of positions.

For example, as shown in FIG. 12A, it is obtained by moving the laser displacement meter R along two linear loci (first locus 4, second locus 5) orthogonal to each other at the real center position β. The conveyed state of the wafer 2 may be estimated based on the measured value. At this time, as shown in FIG. 12B, even if the measured value obtained by moving the laser displacement meter R along the first trajectory 4 is a constant value, the laser displacement meter is along the second trajectory 5. When the measured value obtained by moving R exceeds the upper threshold value, the wafer state estimation unit 36 determines that the measured value exceeding the reference range has been obtained, and estimates that the wafer 2 is not normally arranged.

Further, as shown in FIG. 13A, the laser displacement meter R is moved to an upper position of any six measurement points (6a, 6b, 6c, 6d, 6e, 6f) near the peripheral edge of the wafer 2. , The transfer state of the wafer 2 may be estimated based on the height position of the wafer 2 at each measurement point 6a to 6f. At this time, as shown in FIG. 13B, when 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 normally arranged.

Further, in the first embodiment, an example is shown in which the laser displacement meter R for measuring the distance by the reflected light S2 of the laser light is used as the distance measuring unit for measuring the distance to the object T, but the present invention is not limited to this. For example, it may be a distance measuring device or the like in which a measuring rod that expands and contracts is extended to an object T and the distance is measured by the length of the rod.

Further, in the first embodiment, the example in which the wafer 2 is conveyed to one work hole 14 formed in the carrier 13 is shown, 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, and the wafers 2 can be sequentially arranged in the work holes 14 where the actual center positions have been detected.

Further, the detection of the actual center position β of the work hole 14 may be performed while the wafer 2 is held by the transfer head 21, or may be performed while the wafer 2 is not held. When the real center position β is detected while holding the wafer 2, it is not necessary to drive the arm portion 22 to hold the wafer 2 after detecting the real center position β. Therefore, it is possible to suppress an increase in the transfer time of the wafer 2.

1 Polishing system 2 Wafer 10 Grinding machine 11 Upper surface plate 12 Lower surface plate 13 Carrier 14 Work hole 20 Wafer transfer machine 21 Transfer head 22 Arm unit 30 Main controller 31 Teaching position calculation unit 32 Detection position setting unit 33 Edge detection unit 34 Center calculation Unit 35 Transfer control unit 36 Wafer state estimation unit R Laser displacement meter (distance measuring unit)
α Teaching position β Real center position

Claims (8)

In the work hole detection device that detects the position of the work hole of the carrier placed on the surface plate of the polishing machine.
A distance measuring unit that measures the distance to an object,
An edge detection unit that detects the positions of the edge portions of the work hole at three or more locations using the measured values of the distance measurement unit, and
A central calculation unit that calculates the center position of the work hole based on the positions of three or more edge portions detected by the edge detection unit.
A work hole detection device comprising. In the work hole detection device according to claim 1,
The distance measuring unit is a work hole detection device characterized in that the distance measuring unit is a laser displacement meter that measures the distance by reflected light of a laser beam. In the work hole detection device according to claim 1 or 2.
A work hole detection device including a teaching position calculation unit that calculates a center position of the work hole based on a relative position between the surface plate and the carrier. In the work hole detection device according to any one of claims 1 to 3.
A work hole detection device including a wafer state estimation unit that estimates the transferred state of the wafer based on the height of the upper surface of the transferred wafer measured by the distance measuring unit. In the work hole detection device according to any one of claims 1 to 4.
The distance measuring unit is a work hole detection device characterized in that it is mounted on a wafer transfer machine that conveys wafers into the work hole. In the work hole detection method for detecting the position of the work hole of the carrier placed on the surface plate of the polishing machine,
The first step of detecting the positions of three or more edges of the work hole based on the measured values obtained by measuring the distance to the object while moving the distance measuring unit, and
The second step of calculating the center position of the work hole based on the positions of the edge portions in three or more places, and
A work hole detection method comprising. In the work hole detection method according to claim 6,
In the first step, when the position of the edge portion is detected, the edge portion detection position capable of surrounding the center position of the work hole calculated from the relative position between the surface plate and the carrier is set to three. A work hole detection method characterized in that three or more locations are set and the positions of the edge portions are detected while moving the distance measuring unit from the edge portion detection position. In the work hole detection method according to claim 6 or 7.
After the wafer is transferred, the third step of detecting the height of the upper surface of the transferred wafer using the distance measuring unit, and
The fourth step of estimating the transfer state of the wafer based on the height of the upper surface of the wafer, and
A work hole detection method comprising.

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