JP6397790B2 - Wafer positioning detection apparatus, method and program - Google Patents

Description

  The present invention relates to a wafer positioning detection apparatus, method, and program for detecting the center position of a wafer.

  Of the wafer manufacturing and inspection processes, for example, processes that require positional information of the wafer, such as wafer processing and various inspections, it is necessary to accurately place the wafer on each apparatus. Such a wafer positioning detection apparatus is an apparatus for accurately arranging the position of the center point of the wafer and the notch position of the edge portion of the wafer at a predetermined position as a pre-stage process of the polishing process.

  As a wafer positioning detection device, for example, a thin disk-shaped wafer having a notch portion at the outer peripheral edge portion is held by aligning the center of the wafer and the position of the rotation axis, and a rotating support table, and a laser beam Is applied to the edge portion of the wafer, and the reflected laser beam is detected to detect the position of the edge portion and the position of the notch portion, and the amount of eccentricity, the direction of eccentricity and the notch portion of the wafer from the sensor position data. What is provided with the calculating device which calculates a rotation angle position etc. are known (for example, refer to patent documents 1).

JP 2009-246027 A

  Here, the shape and the like of the wafer 2 will be described with reference to FIGS. 18 and 19. FIG. 18 is a diagram for explaining a cut-out state of the wafer, and FIG. 19 is a diagram showing a difference between the perfect circle shape and the elliptical shape of the wafer.

  In view of the characteristics in wafer production, as shown in FIG. 18, for example, the ingot 20 is cut out along the direction inclined at an angle of 4 degrees (angle φ) from the vertical cross-sectional direction V, so that the cut out wafers 2a, 2b, 2c, etc. Becomes a substantially disk-shaped wafer 2.

  The notch 21 is a processed groove for indicating the crystal orientation in the ingot 20. In FIG. 18, the wafer 2c cut out from the vertical cross-sectional direction V at an angle φ is actually an elliptical cross section. For example, the wafer 2c includes an ellipse having a long side rx, a short side ry, and a center Cw.

  Such a wafer 2 originally needs to calculate the shape, radius, center, etc. as an ellipse, but the conventional wafer positioning detection device calculates the shape of a circle. For example, as shown in FIG. 19, the shape, radius, center, and the like are different even when the notches 21 are aligned, such as a center Mw on a circular shaped wafer 22 and a center Cw on an elliptical shape (wafer 2). .

  Conventionally, for example, the wafer radius of the wafer 2 is measured by a laser measuring device installed in a line shape, and the wafer radius and the amount of eccentricity are calculated by using the least squares method for calculating the true circle. Although the wafer 2 originally has an elliptical shape due to the production characteristics of the wafer 2 as described above, in the wafer measurement process, the wafer radius and the amount of eccentricity were calculated using a perfect circle calculation formula. It was. For example, in FIG. 18, when the wafer 2c has an elliptical shape, the long side rx, the short side ry, and the center Cw as an ellipse need to be calculated, but are calculated in the shape of a circle.

  The error due to the above factors is negligible because this error is small when the wafer radius is small, but the error also increases as the wafer size increases, so when the wafer radius is large, An accurate elliptical center Cw could not be calculated. For this reason, the amount of eccentricity with respect to the center Cw of the elliptical shape becomes large. For example, as shown in FIG. 19, there has been a problem that polishing cannot be performed to a perfect circle (center Mw) unless a large amount of polishing is set in the polishing step. In addition, there is a problem that the life of the grindstone is shortened by increasing the polishing amount.

  Further, conventionally, since the wafer radius and the center Cw are calculated including the measurement data caused by irregular elements such as foreign matters adhering to the outer peripheral edge of the wafer 2 or chipping of the wafer 2, an extra error occurs. It was. That is, for example, when a foreign matter adheres to the outer peripheral edge of the wafer 2, the wafer radius that is longer than the original when no foreign matter is attached is measured, and when the outer peripheral edge of the wafer 2 is chipped, In addition, the calculation was made including all of the measured wafer radii that were shortened. Therefore, an extra error has occurred in the calculated wafer radius and eccentricity.

  Furthermore, due to the above error, an error has occurred in the notch position in the detection of the notch position at the outer peripheral edge.

  In order to solve such a problem, it is necessary to calculate the center Cw of the wafer from only the measurement data, excluding the measurement data caused by irregular elements as much as possible.

  Accordingly, the problem to be solved by the present invention is to provide a wafer positioning detection device that extracts measurement data capable of calculating an accurate radius of a wafer from measurement data with respect to the outer peripheral edge of the wafer and accurately calculates the center of the wafer. That is.

  Another object of the present invention is to provide a wafer positioning detection method that extracts measurement data capable of calculating an accurate radius of a wafer from measurement data with respect to the outer peripheral edge of the wafer and accurately calculates the center of the wafer. That is.

  Further, the problem to be solved by the present invention is to extract a measurement data capable of calculating an accurate radius of the wafer from the measurement data with respect to the outer peripheral edge of the wafer, and to execute a computer program for accurately calculating the center of the wafer. Is to provide.

  In order to solve the above-described problems, a wafer positioning detection apparatus according to the present invention is a wafer positioning detection apparatus that detects the center of a substantially disk-shaped wafer having a notch at an outer peripheral edge. The wafer positioning detection device is configured to place the wafer and rotate while holding the rotation center of the wafer and the axis center of the rotation axis together, and to measure the rotation angle of the rotation axis. It is possible to install the wafer at a predetermined distance from the measurement table in the vicinity of the outer peripheral edge of the wafer, and irradiate laser light in a direction perpendicular to the substantially disk-shaped surface of the wafer. A laser measuring unit that receives and measures light to measure a distance from the outer peripheral edge of the wafer; a wafer radius from the rotation center of the wafer to the outer peripheral edge of the wafer; and an eccentricity from the rotation center with respect to the center of the wafer An arithmetic unit for calculating the quantity and the eccentric direction. The outer diameter of the measurement table is formed smaller than the outer diameter of the wafer, the measurement table is rotated by the laser measurement unit so that the distance from the outer peripheral edge of the wafer over the entire circumference of the wafer can be measured, The arithmetic device is a measurement data acquisition unit that acquires measurement data including the wafer radius calculated from the rotation angle and a distance between the laser measurement unit measured for each rotation angle and the outer peripheral edge of the wafer; A storage unit for storing the measurement data acquired by the measurement data acquisition unit, and a difference in the wafer radius at the rotation angle at a predetermined comparison angle interval for a predetermined radius of the wafer radius stored in the storage unit. A determination is made whether the wafer radius is within a threshold, and all the wafer radii in a continuous rotation angle range are Using the effective data group extraction unit that extracts the measurement data determined to be within a value as an effective data group and the extracted effective data group, statistically calculate the outer peripheral edge of the wafer based on an elliptic equation And a statistical calculation unit that calculates the amount of eccentricity and the direction of eccentricity based on the peripheral edge that has been statistically calculated.

  Further, in the wafer positioning detection device according to the present invention, the effective data group extraction unit prioritizes an effective data group having a longer arc length in each measurement section from the extracted effective data group, The main feature is that the effective data group up to the priority order is further extracted and used by the statistical calculation unit.

  Furthermore, in the wafer positioning detection device according to the present invention, the measurement data acquisition unit overlaps the measurement range for the entire circumference of the wafer from the measurement start angle to the constant angle range until the measurement end angle is reached. The main feature is that the measurement data is acquired so as to have an overlap interval to be measured.

  Furthermore, the wafer positioning detection device according to the present invention is based on the reference groove depth from the measurement data stored in the storage edge and the outer peripheral edge of the wafer that is statistically calculated by the arithmetic device. The main feature is that it further includes a notch determination unit for determining the position of the notch.

  In addition, the wafer positioning detection apparatus according to the present invention is characterized in that the statistical calculation unit statistically calculates the outer peripheral edge of the wafer using the least square method on the elliptic equation.

  Furthermore, in the wafer positioning detection device according to the present invention, the arithmetic unit, based on the amount of eccentricity and the direction of eccentricity, the center of the wafer and the rotation center of the next process table for placing the wafer in the next process, And an adjustment data notification unit for notifying adjustment data related to the center of the wafer to the apparatus in the next process.

  In order to solve the above problems, a wafer positioning detection method according to the present invention includes a measurement table and a laser measurement unit, and a wafer having a substantially disk shape having a notch at an outer peripheral edge is placed on the measurement table. This is a wafer positioning detection method used in a wafer positioning detection device that detects the center of the wafer. The outer diameter of the measurement table is formed smaller than the outer diameter of the wafer, and the wafer positioning detection device performs the following steps, that is, the rotation center of the placed wafer and the rotation axis of the measurement table. A rotation measurement step of measuring the rotation angle of the rotation axis by rotating the measurement table while keeping the axis center of the wafer in alignment with the axis of the wafer, and a substantially disk-shaped surface of the wafer in the vicinity of the outer peripheral edge of the mounted wafer A distance measurement step of irradiating the laser beam perpendicularly to the laser measurement unit, measuring the radius of the wafer from the rotation center of the wafer to the outer peripheral edge of the wafer by receiving and measuring the irradiated laser beam; Based on the wafer radius measured by the distance measuring step, the center of rotation of the wafer from the center of rotation. Performing a calculation step of calculating the heart weight and the eccentric direction. The calculation step is further acquired by the measurement data acquisition step of acquiring measurement data including the rotation angle and the wafer radius measured by the distance measurement step for each rotation angle, and the measurement data acquisition step. A storage step for storing the measurement data, and a threshold determination step for determining whether or not the difference in the wafer radius at the rotation angle is within a predetermined threshold at every predetermined comparison angle interval for the stored wafer radius. And an effective data group extraction step for extracting, as an effective data group, the measurement data in which all the wafer radii in a continuous rotation angle range are determined to be within the predetermined threshold, and the extracted effective data Using the group, statistically calculate the peripheral edge of the wafer based on the elliptic equation, Based on the outer peripheral edge which is calculated as a main feature in that it comprises a statistical calculation step of calculating the amount of eccentricity and the eccentric direction.

  Furthermore, in order to solve the above problems, a wafer positioning detection program according to the present invention includes a computer, a measurement table and a laser measurement unit, and a substantially disk-shaped wafer having a notch at the outer peripheral edge is placed on the measurement table. And a wafer positioning detection program for detecting the center of the wafer and operating as a wafer positioning detection device in which the outer diameter of the measurement table is smaller than the outer diameter of the wafer. The wafer positioning detection program rotates the measurement table and measures the rotation angle of the rotation shaft while holding the rotation center of the mounted wafer and the axis center of the rotation shaft of the measurement table. Measuring step, irradiating a laser beam by the laser measuring unit in a direction perpendicular to a substantially disk-shaped surface of the wafer in the vicinity of the outer peripheral edge of the mounted wafer; A distance measuring step for measuring a wafer radius from the rotation center of the wafer to the outer peripheral edge of the wafer, and an eccentric amount from the rotation center with respect to the center of the wafer based on the wafer radius measured by the distance measurement step, and A calculation step for calculating an eccentric direction. The calculation step is further acquired by the measurement data acquisition step of acquiring measurement data including the rotation angle and the wafer radius measured by the distance measurement step for each rotation angle, and the measurement data acquisition step. A storage step for storing the measurement data, and a threshold determination step for determining whether or not the difference in the wafer radius at the rotation angle is within a predetermined threshold at every predetermined comparison angle interval for the stored wafer radius. And an effective data group extraction step for extracting, as an effective data group, the measurement data in which all the wafer radii in a continuous rotation angle range are determined to be within the predetermined threshold, and the extracted effective data Using the group, statistically calculate the peripheral edge of the wafer based on the elliptic equation, Based on the outer peripheral edge which is calculated as a main feature in that it comprises a statistical calculation step of calculating the amount of eccentricity and the eccentric direction.

  According to the wafer positioning detection apparatus, method and program according to the present invention, it is possible to extract measurement data capable of calculating an accurate radius of a wafer from measurement data with respect to the outer peripheral edge of the wafer and accurately calculate the center of the wafer. .

It is a figure which shows the structure of embodiment of the wafer positioning detection apparatus which concerns on this invention. It is a figure which shows arrangement | positioning of the laser measurement unit at the time of the wafer measurement state in a measurement table. It is a figure for demonstrating an example of the wafer of measurement object, and measurement data. It is a figure for demonstrating the overlap area at the time of the measurement of a wafer. It is a block diagram which shows an example of a structure of the arithmetic unit shown in FIG. It is a figure for demonstrating the threshold determination process with respect to measurement data. It is a figure which shows an example of the effective data group determination process with respect to measurement data, and a statistical calculation process. It is a figure for demonstrating a notch determination process. It is a figure which shows an example of the centering result of a wafer. It is a figure which shows an example of the wafer positioning result in a polishing table. It is a figure which shows an example of the setting data with respect to a calculating device. It is a flowchart of the wafer positioning detection process used for the wafer positioning detection apparatus of FIG. It is a flowchart which shows the detail of the wafer radius measurement process of FIG. It is a flowchart which shows the detail of the effective data group determination process of FIG. It is a flowchart which shows the detail of the notch determination process of FIG. FIG. 16 is a flowchart showing a continuation of details of the notch determination processing of FIG. 15. It is a block diagram which shows an example of the hardware constitutions of the arithmetic unit shown in FIG. It is a figure for demonstrating the cutting-out state of a wafer. It is a figure which shows the difference with the perfect circle shape and elliptical shape of a wafer.

  Hereinafter, a wafer positioning detection device according to an embodiment of the present invention will be specifically described with reference to the drawings. Here, the same or similar parts are denoted by common reference numerals, and redundant description is omitted. In the following embodiment described here, an example from the wafer positioning detection process for measuring the center of the cut wafer to the polishing process as the next process will be described.

  Hereinafter, the configuration of an embodiment of a wafer positioning detection apparatus according to the present invention will be described with reference to FIGS. Here, FIG. 1 is a diagram showing a configuration of an embodiment of a wafer positioning detection apparatus 1 according to the present invention. FIG. 2 is a diagram showing the arrangement of the laser measurement units 5 in the wafer measurement state on the measurement table. Other figures will be described sequentially.

  The apparatus shown in FIG. 1 mainly moves an apparatus used for a wafer positioning detection process (wafer positioning detection apparatus 1), an apparatus used for a polishing process (grinding stone 7 and polishing table 8), and a wafer 2 between processes. It is the conveyance apparatus (conveyance arm 3 and conveyance rail 6) for making it convey. The wafer positioning detection device 1 will be described in detail later, and hereinafter, the grindstone 7, the polishing table 8, the transfer arm 3, and the transfer rail 6 will be described.

  The transfer arm 3 can transfer between the tables via the transfer rail 6 while maintaining the posture of the wafer 2 during transfer. For this purpose, the transfer arm 3 includes a suction unit 31 that can fix and release the wafer 2 by suction, and a lift arm 32 that can be extended and contracted in the vertical direction by connecting the suction unit 31 to the lower tip. Thereby, the transfer arm 3 lifts up the wafer 2 from the table of each process, and enables the wafer 2 to be lifted down (placed) on the table. The center Cw of the wafer 2 placed on the measurement table 4 is slightly decentered from the rotation center Or of the measurement table 4 if the outer peripheral edge of the wafer 2 is in a position range that can be measured by the laser measurement unit 5. Also good.

  The transfer rail 6 is a laying rail for moving the transfer arm 3 so that the wafer 2 can be transferred to a predetermined table between each process, for example, between the measurement process and the polishing process. The transport rail 6 transports the transport target (wafer 2) to a target transport position in a stable floating posture. Further, the transfer rail 6 transmits and receives transfer data related to, for example, placement of the transfer object (wafer 2), pickup timing notification, transfer command, and the like between the wafer positioning detection device 1 and the polishing table 8.

  The polishing table 8 is a table on which the wafer 2 is placed and polished by the grindstone 7 during the polishing process. The polishing table 8 can hold the wafer 2 firmly so that the mounted wafer 2 can be polished by the grindstone 7. For this purpose, the polishing table 8 can, for example, hold the wafer 2 by suction.

  Further, the polishing table 8 is provided with a polishing table rotating shaft 81 so as to be connected to the lower side of the table surface so as to rotate about the center of the table surface of the polishing table 8 as a rotation center. Thereby, the polishing table 8 is rotatable.

  Further, for example, the polishing table rotation shaft 81 is movable in the X direction and the Y direction on a two-dimensional plane parallel to the table surface, and adjusts the eccentric amount and the eccentric direction of the wafer 2 to thereby adjust the wafer. When placing 2, the position of the center Cw of the wafer 2 can be aligned with the center of rotation of the polishing table 8.

  As a result, the polishing table 8 receives the eccentric amount of the wafer 2 notified from the wafer positioning detection device 1 when the wafer 2 transported from the measurement table 4 is placed by the transport arm 3 via the transport rail 6. The wafer 2 can be mounted with the position of the center Cw of the wafer 2 aligned with the rotation center of the polishing table 8 based on the adjustment data including at least the eccentric direction.

  The grindstone 7 is an abrasive for polishing the outer peripheral edge portion of the wafer 2. The grindstone 7 can be freely rotated in the reverse and forward directions and the rotation speed can be freely controlled in accordance with the rotation direction of the polishing table 8.

  The wafer 2 is chamfered all around by the rotation of the grindstone 7 and the rotation of the polishing table 8. For example, chamfering is performed so that the elliptical wafer 2 as shown in FIG.

  In the next polishing step, the adjustment data notified from the wafer positioning detection device 1 can be used to match the center Cw of the wafer 2 and the rotation center (rotation axis center) of the polishing table 8, so that when chamfering The amount of polishing in the wafer 2 can be reduced. Thereby, it can also lead to the reduction of the cycle time in a grinding | polishing process, and the wear degree of the grindstone 7 can also be suppressed.

  Hereinafter, the wafer positioning detection apparatus 1 will be described with reference to FIGS. 1 and 2. Here, in FIG. 2, FIG. 2A is a side view showing the wafer measurement state in the measurement table 4, and FIG. 2B is a top view showing the wafer measurement state in the measurement table 4 (FIG. 2A). Is a line of sight from the direction Fu shown in FIG.

  The wafer positioning detection device 1 detects the center of a substantially disk-shaped wafer 2 having a notch 21 at the outer peripheral edge. For this purpose, the wafer positioning detection apparatus 1 includes a measurement table 4, a laser measurement unit 5, and an arithmetic unit 10, as shown in FIG. Here, the laser measuring unit 5 is described as an example of the measuring means for measuring the outer peripheral edge of the wafer 2, but even if it is not a laser measuring unit, for example, a stylus type roundness measuring machine, In addition, any measuring instrument capable of measuring the diameter of the wafer from the outer peripheral edge of the wafer can be adopted. Therefore, in the present invention, the laser measurement unit is not necessarily limited to a measurement apparatus using a laser, and includes all other measuring instruments that can measure the diameter of the wafer from the outer peripheral edge of the wafer. However, at present, a laser using a laser is preferable because of its accuracy and convenience.

  The measurement table 4 is placed on the wafer 2 and rotated while holding the rotation center Or of the wafer 2 and the position of the rotation shaft 41, and the rotation angle θi of the rotation shaft 41 can be measured. Therefore, the measurement table 4 is formed in a thin disk shape, and the outer diameter of the disk shape is smaller than the outer diameter of the wafer 2. The rotation shaft 41 is connected to the center of the lower side of the disk so that the axis center Jr of the rotation shaft 41 passes through the rotation center Or of the disk of the measurement table 4.

  The measurement table 4 can be freely controlled by a rotating shaft 41. As shown in FIGS. 2A and 2B, the measurement table 4 is placed on the wafer 2 and rotates while holding the rotation center Or of the wafer 2 and the axis center Jr of the rotation shaft 41. . The measurement table 4 can measure the rotation angle θi of the rotary shaft 41. The measurement table 4 is rotated by the laser measurement unit 5 so that the distance di from the outer peripheral edge of the wafer 2 over the entire circumference of the wafer 2 can be measured.

  The laser measurement unit 5 can be installed in the vicinity of the outer peripheral edge of the mounted wafer 2 and on the measurement reference position MesLine shown in FIG. The laser measurement unit 5 irradiates the laser beam 53 in a direction perpendicular to the substantially disk-shaped surface of the wafer 2, receives and measures the irradiated laser beam 53, and measures the distance from the outer peripheral edge of the wafer 2. To do. In the example shown in FIG. 2B, the measurement rotation angle θi = θn and the position of the notch 21 on the measurement reference position MesLine is a range to be measured.

  For this purpose, the laser measuring unit 5 includes a laser projector 51 and a laser receiver 52 configured in a line. The laser beam 53 emitted from the laser projector 51 can be received and measured by the opposing laser receiver 52. Thereby, the distance from the outer peripheral edge of the wafer 2 by the laser measurement unit 5 is the length of the portion where the laser beam 53 is shielded or the length of the portion where the laser beam 53 is not shielded based on the linear light reception measurement (light receiving width). It can be calculated by calculating the thickness.

  The arithmetic unit 10 includes a measurement table 4, a laser measurement unit 5, devices used for the polishing process (grinding stone 7 and polishing table 8), and a transfer device (transfer arm 3 and transfer rail 6) for moving the wafer 2 between the processes. Can communicate with each other (data can be transmitted / received between them). For example, the communication means may be wired communication or wireless communication. Moreover, these combinations may be sufficient.

  The arithmetic device 10 acquires measurement data including at least the distance di from the outer peripheral edge of the wafer 2 and the rotation angle θi from these devices. In addition to this, the measurement data may include a measurement date and time, an identification number that can identify the measurement target wafer 2, a measurement result in the measurement table 4 (measurement impossible or the number of remeasurements), and the like.

  Based on the measurement data as described above, the arithmetic unit 10 calculates the wafer radius ri from the rotation center Or of the wafer 2 to the outer peripheral edge of the wafer 2, the eccentric amount and the eccentric direction from the rotation center Or with respect to the center Cw of the wafer 2. And can be calculated.

[Description of overall overview]
Below, the operation | movement outline | summary of the wafer positioning detection apparatus 1 is demonstrated.

  (1) The wafer 2 is set on the measurement table 4 by the transfer rail 6 and the transfer arm 3 shown in FIG. At this time, the center Cw of the wafer 2 and the rotation center Or of the measurement table 4 do not have to coincide with each other, and the wafer 2 is placed in the measurement table 4 so that the center Cw of the wafer 2 is positioned at a substantially central portion of the measurement table 4. Placed on.

  (2) The laser measurement unit 5 is movable and approaches the measurement table 4 side from a position separated from the outer peripheral edge of the mounted wafer 2, for example, a leftward position (on the paper surface of FIG. 2A). To move. The laser measurement unit 5 is located at a position corresponding to the outer diameter size of the wafer 2 so as to sandwich the wafer 2 placed on the measurement table 4 between the laser projector 51 and the laser receiver 52 (shown in FIG. 2A). (Positions corresponding to Pos # 1, # 2, and # 3). The laser measuring unit 5 includes a laser projector 51 and a laser receiver 52 configured in a line, and measures the length of a portion where the laser beam 53 is shielded or the length of a portion where the laser beam 53 is not shielded. Thereby, the wafer radius ri of the wafer 2 can be measured.

  For example, when the distance between the laser measurement unit 5 and the outer peripheral edge of the wafer 2 is di (corresponding to the length of the unshielded portion) and the position where the laser measurement unit 5 is arranged is Pos # 1, the rotation of the wafer 2 is performed. When the separation distance of the laser measurement unit 5 from the center Or is Len # 1, it can be obtained as wafer radius ri = Len # 1-di. In the case of being arranged at Pos # 2 and # 3, the distances Len # 2 and # 3 of the laser measurement unit 5 from the rotation center Or of the wafer 2 are set.

  (3) The measurement table 4 rotates one or more times, and during this time, the arithmetic unit 10 acquires the measured wafer radius ri of the entire circumference of the wafer 2 and the rotation angle θi at that time. At this time, the wafer radius ri of the entire circumference of the wafer 2 is measured in an overlapping manner. Here, the term “overlap” means that measurement is repeated from the measurement start angle to a certain angle range until the measurement end angle is reached.

  FIG. 3 is a diagram for explaining an example of the wafer 2 to be measured and measurement data. In particular, FIG. 3A is a top view showing a measurement state of the wafer 2 having foreign matters or defects. FIG. 3B is a diagram for explaining an example of measurement data (θi, ri) at the measurement reference position MesLine. FIG. 4 is a diagram for explaining the overlap interval Δθv when measuring the wafer 2.

  For example, it is assumed that the wafer positioning detection apparatus 1 measures a wafer 2 having foreign matters and defects as shown in FIG. Here, in Fig.3 (a), it is edge | side L # 1-L # 8, L # 9 (same side as L # 1) of an outer periphery edge, the notch 21 (predetermined groove | channel), the deposit | attachment 211, and big This is due to irregular elements as measurement data such as the deposit 213 and the defect 212. Note that the side L # 9 having the overlap section Δθv may be L # 1.

  For example, as a result of measuring the outer peripheral edge of the wafer 2 in FIG. 3A, measurement data (θi, ri) at the measurement reference position MesLine as shown in FIG. 3B is measured. Note that, in the sides L # 2, L # 4, L # 6, and L # 8 shown in FIG. 3B, measurement is performed at the position in the angular range corresponding to the deposit 211, the notch 21, the defect 212, and the large deposit 213. Indicates that data is being acquired.

  In the example of FIG. 4, the overlap section Δθv at the time of measuring the wafer 2 overlaps from the measurement start angle to the constant angle range in the measurement range for the entire circumference of the wafer 2 until the measurement end angle is reached. It is a section to measure. In the example of FIG. 4, the rotation angle θi (for example, 0 degree) at the measurement reference position MesLine at the start of measurement is set as the measurement start angle, and the rotation angle θi (for example, 370 degree) at the measurement reference position Mesline at the end of measurement is measured. The end angle. Note that the position of MesLine in FIG. 4 indicates the position at the end of measurement.

  For example, when the rotation angle is measured in the range of 0 to 370 degrees, the measurement start angle = 0 degrees, the measurement end angle = 370 degrees, and the overlap section Δθv = 360 to 370 degrees. That is, the measurement range from the measurement start angle of 0 to 10 degrees is overlapped and measured at 360 to 370 degrees before reaching the measurement end angle of 370 degrees (referred to as overlap measurement).

  In the method in which the overlap measurement is not performed, the measurement range is exactly the entire circumference (0 to 360 degrees) when dust is attached to the measurement position at the rotation start at the measurement reference position MesLine or when there is a notch position. Sometimes it is difficult to distinguish. For example, if dust or the like is attached to the outer peripheral edge near the measurement point at the start of measurement, the dust is attached near the rotation angle of 0 °, but the dust is removed before the rotation angle of 360 ° during rotation. For example, the measurement data near the rotation angle after 0 degrees and the rotation angle near 360 degrees before may be unnatural data in the data connection. Conventionally, since the data is unnatural in the connection of data at around 0 degrees, for example, the rotation start position is shifted and the rotation is rotated once again and remeasured.

  On the other hand, in the method of performing the overlap measurement, for example, when dust or the like at the measurement point at the start of measurement is attached to the outer edge, the measurement data near the rotation angle after 0 degree and around 360 degrees before the rotation angle are described above. Even if it is such unnatural data, continuous measurement data (for example, the side L # 9 shown in FIG. 3A) from the vicinity of 360 degrees before the rotation angle to the overlap section Δθv can be obtained by measuring the overlap. For example, calculation using the measurement data corresponding to (1).

  As described above, by measuring the overlap, the change before and after the outer peripheral edge at the wafer radius measurement position at the start of measurement rotation can be accurately captured.

(4) Valid Data Group Determination The arithmetic unit 10 determines whether or not the difference of the wafer radius ri at the rotation angle θi is within a predetermined threshold Δrth for each measured comparison radius interval Δθd for the measured wafer radius ri. Then, using this determination result, a cluster of continuous data of the outer peripheral edge for which it is determined that all the wafer radii ri within the continuous rotation angle range are within the predetermined threshold Δrth is extracted as an effective data group. Using the extracted effective data group, statistical calculation of the outer peripheral edge of the wafer 2 is performed based on the elliptic equation.

  The arithmetic unit 10 calculates the center Cw of the wafer 2 based on the effective data group, and calculates the eccentric amount and the eccentric direction φc (shown in FIG. 4). Further, the position of the notch 21 is determined based on the calculated elliptical shape of the wafer 2 and measurement data. The notch position determination process related to the notch 21 will be described later in detail.

  (5) After the measurement of the arithmetic unit 10 is completed, the laser measurement unit 5 and the wafer 2 are returned to their original positions.

  (6) In the polishing step, the position of the center Cw and the notch 21 of the wafer 2 is adjusted to the reference position (Ref reference: for example, 0 degree position) on the polishing table 8, and the polishing table 8 is moved to the polishing table 8 by the transfer rail 6 and the transfer arm 3. Move.

  When moving to the polishing table 8, the amount of eccentricity obtained by calculation can be eliminated by moving the polishing table 8. For example, the polishing table 8 is moved so that the center Cw of the wafer 2 and the rotation center of the polishing table 8 coincide. Further, the polishing table 8 is rotated so that the position of the notch 21 is 0 degree in accordance with the reference position. Note that it may be a means or a method for rotating the transfer arm 3 (suction unit 31) to adjust the position of the notch 21 to the reference position (0 degree).

  (7) Chamfering the entire circumference of the wafer 2 by the rotation of the grindstone 7 and the rotation of the polishing table 8. When chamfering, the center Cw of the wafer 2 and the center of rotation of the polishing table 8 are matched, so that the polishing amount is minimized and the cycle time is reduced. Further, since the polishing amount is minimized, damage to the wafer 2 is reduced, and the life of the grindstone 7 is improved.

[Explanation of arithmetic unit]
FIG. 5 is a block diagram showing an example of the configuration of the arithmetic device 10 shown in FIG.

  As shown in FIG. 5, the calculation device 10 includes a measurement data acquisition unit 11, a storage unit 12, a valid data group extraction unit 13, a statistical calculation unit 14, a notch determination unit 15, an adjustment data notification unit 16, and an input / output setting unit. 17.

  The measurement data acquisition unit 11 acquires measurement data including the rotation angle θi and the distance di between the laser measurement unit 5 and the outer peripheral edge of the wafer 2 measured at predetermined rotation angle intervals. Thereby, for example, when the position where the laser measurement unit 5 is arranged is Pos # 1, the wafer radius ri = Len # based on the separation distance Len # 1 of the laser measurement unit 5 from the rotation center Or of the wafer 2. It can be obtained as 1-di.

  As described above, the measurement data acquisition unit 11 sequentially acquires measurement data including the rotation angle θi from the measurement table 4 and the wafer radius ri of the wafer 2 from the laser measurement unit 5, and the rotation angle θi is the measurement end angle. Check if you have reached.

  Further, the measurement data acquisition unit 11 transmits an instruction regarding measurement start / end to each device, and receives a command / response from each device. Specifically, the measurement data acquisition unit 11 instructs the laser measurement unit 5 to place the laser measurement unit 5 at a position corresponding to the wafer diameter among the reference positions Pos # 1 to # 3. Send instructions to return to the isolation position. In addition, for example, the measurement data acquisition unit 11 sends a rotation start instruction, a rotation stop instruction, and the like to the measurement table 4.

  The storage unit 12 stores the measurement data acquired by the measurement data acquisition unit 11. In addition, data necessary for storage can be sequentially stored by the effective data group extraction unit 13, the statistical calculation unit 14, the notch determination unit 15, the input / output setting unit 17, and the like in the calculation device 10.

  The effective data group extraction unit 13 determines the difference in the wafer radius ri corresponding to the rotation angle θi for each predetermined comparison angle interval Δθd based on the predetermined threshold Δrth for the wafer radius ri of the measurement data stored in the storage unit 12. Then, the presence / absence of validity (not caused by irregular elements) as outer periphery data is determined. That is, it is determined whether or not the difference in wafer radius at the rotation angle θi is within a predetermined threshold Δrth at every predetermined comparison angle interval Δθd. Using this determination result, the effective data group extraction unit 13 extracts, as an effective data group, measurement data determined that all wafer radii ri within a continuous rotation angle range are within a predetermined threshold Δrth.

  The statistical calculation unit 14 statistically calculates the outer periphery of the wafer 2 based on the elliptic equation using the effective data group extracted by the effective data group extraction unit 13.

  Hereinafter, the processes of the valid data group extraction unit 13 and the statistical calculation unit 14 will be described in detail with reference to FIGS. 6 and 7.

[Threshold determination processing]
FIG. 6 is a diagram for explaining threshold determination processing for measurement data in the valid data group extraction unit 13.

  The effective data group extraction unit 13 compares the wafer radii from the acquired wafer radius ri at predetermined comparison angle intervals Δθd as shown in FIG. If the wafer 2 is normal (except for the notch 21), these comparison results are only due to the eccentricity difference in the wafer radius ri. The difference occurs.

  The valid data group extraction unit 13 uses the threshold value determination process described below to compare the result of comparison of the wafer radii (difference Cmp # i) at each predetermined comparison angle interval Δθd, thereby irregularities such as foreign matter and defects. It is determined that the measurement data is attributed to the element.

  Further, when comparing the adjacent data with fine sampling when comparing, it is difficult to detect a change caused by irregular elements when the measurement data of the foreign matter and the defect is a gradual change. ) Are compared with each other.

  For example, as shown in FIG. 6, the comparison angle interval for the measurement data such as differences Cmp # 1 = | a1-a2 |, Cmp # 2 = | b1-b2 |, Cmp # 3 = | c1-c2 | The difference Cmp # i is taken for each Δθd. Note that a1, b1, c1, etc. are data of the wafer radius ri at each adjacent sampling rotation angle.

  Then, the valid data group extraction unit 13 compares the difference Cmp # i with a predetermined threshold value Δrth. If the difference Cmp # i is within a predetermined threshold value Δrth, it is determined that the data is continuous data as the outer peripheral edge of the wafer 2. On the other hand, when the predetermined threshold value Δrth is exceeded, it is determined that the measurement data is caused by irregular elements such as foreign matters or defects, and the outer peripheral edge of the wafer 2 is discontinuous data. Thereby, the continuous data of the outer peripheral edge part of the wafer 2 can be determined.

  Here, for example, when the wafer diameter is 300 (mm) and the sampling interval is about 0.05 degrees, the comparison is performed by comparing the comparison angle interval Δθd with a distance of about 0.3 degrees or more. The threshold value Δrth is detected as about 14 μm.

[Extraction processing of valid data group]
7A shows a valid data group determination process for the measurement data in the valid data group extraction unit 13, and FIG. 7B shows an example of the statistical calculation process in the statistical calculation unit 14.

  Next, the valid data group extraction unit 13 extracts a stable continuous data cluster (also referred to as a valid data group) free from foreign objects and defects from the comparison result.

  Here, before and after the discontinuous data measurement point, when the foreign matter or missing portion is long in the measurement angle range, it may be determined by the continuous data. Therefore, in order to exclude the continuous data due to these irregular elements even when foreign matter or missing parts are detected in a long measurement angle range, the longest side of the outer peripheral part is extracted from the extracted effective data group. For example, a high priority is assigned from the long side, such as second and third.

  In other words, the valid data group extraction unit 13 gives high priority to the extracted valid data group from the longest side of the outer peripheral portion and the long side, for example, the second and third. These are ranked as an effective data group of each rank. Then, the valid data group extraction unit 13 further extracts valid data groups from these valid data groups to a predetermined priority order.

  Using the measurement data belonging to the effective data group up to the predetermined priority, the statistical calculation unit 14 calculates an ellipse. Specifically, for example, there may be a side L # 8 of the effective data group corresponding to the portion of the foreign matter (large deposit 213) shown in FIG. 3A, so all the effective data groups are used. Instead, an effective data group that is preferably several stable edges with high priority is used for the calculation of the ellipse.

(Example of valid data group judgment)
For example, in the case of the measurement data shown in FIGS. 3A and 3B, the effective data group extraction unit 13
L # 1: Second stable edge (priority order 2 of valid data group)
L # 2: Foreign matter portion (discontinuous data)
L # 3: 3rd stable edge (priority order 3 of valid data group
)
L # 4: missing or notched part (discontinuous data)
L # 5: Most stable edge (priority 1 of valid data group)
L # 6: missing or notched part (discontinuous data)
L # 7: Fourth stable edge (priority order 4 of valid data group)
L # 8: Foreign matter portion (priority order 5 of valid data group)
It is determined as shown.

  For example, the statistical calculation unit 14 is used for the calculation (the least square method) of the wafer radius ri and the eccentricity of the wafer 2 based on the top three effective data groups of the priorities of the sides on the outer peripheral edge. For example, in the case of the measurement data shown in FIGS. 3A and 3B, as shown in FIG. 7A, the sides L # 1, L # 3, and L # 5 of the valid data group are valid with high priority. It is used when computing an ellipse 2Q (shown in FIG. 7B) as a data group.

[Calculation method for obtaining ellipse]
The statistical calculation unit 14 statistically calculates the outer periphery of the wafer 2 by applying the effective data group extracted by the effective data group extraction unit 13 as described above to the elliptic equation. The statistical calculation unit 14 stores the obtained result in the storage unit 12.

  Hereinafter, an example of the elliptic equation will be described. In view of the production characteristics of the wafer 2, as shown in FIG. 18, for example, the elliptical wafer 2 c is cut at an angle of φ = 4 degrees from the vertical cross-sectional direction V with respect to the rod shape (longitudinal direction) of the ingot 20. Therefore, it is necessary to calculate with an elliptic equation instead of a circle equation. Therefore, for example, the following expression, which is a calculation expression of the least square method, is used as the calculation expression used in the calculation of the radius and the eccentricity.

In the elliptic equation, as shown in FIG. 7B, the center point of the ellipse 2Q is the coordinate (X _O , Y _O ), and the coordinates (Xi, Yi) belonging to the extracted effective data group for obtaining the ellipse 2Q are used. And The length in the X-axis direction (long side) is a, the length in the Y-axis direction (short side) is b, and the inclination of the ellipse 2Q is θ. Here, i is a positive number for indicating a plurality of coordinate points.

  When the formula shown in (Expression 1) is applied to the determinant of the least square method, the determinant shown in (Expression 2) below is obtained.

From the values of determinants A to E shown in (Equation 2), the center coordinates (X _O , Y _O ) of the ellipse 2Q are obtained by the following equation (Equation 3). Thus, for example, when the coordinate of the rotation center Or of the wafer 2 is (0, 0), it can be regarded as eccentric if the center coordinate of the ellipse 2Q is not (0, 0). By shifting the amount and placing the wafer 2, the center of rotation of the polishing table 8 and the center Cw of the wafer 2 can be matched.

  The inclination θ of the ellipse 2Q is obtained from the following equation (Equation 4).

  The inclination θ of the ellipse 2Q is not related to the amount of eccentricity, but the ellipse 2Q that serves as a reference for the wafer 2 necessary for the determination of foreign matter / defects can be obtained.

  The length a in the X-axis direction (long side) and the length b in the Y-axis direction (short side) at an arbitrary angle (inclination θ) can be calculated from the following equation (Equation 5). If the length at an arbitrary angle is known, it is possible to determine whether the measurement data is data resulting from irregular elements, whether it is a deep groove of the notch 21 or not.

  As described above, according to the present invention, measurement data caused by irregular elements such as foreign matters and defects can be removed by determining and extracting a valid data group, so that no extra error is included. be able to. Thereby, the measurement data caused by the defect of the outer peripheral edge of the wafer or the attached foreign matter is excluded and the calculation is performed with the shape of the wafer as an ellipse, so that the center position of the wafer can be detected with high accuracy. As a result, the wafer positioning accuracy in the next process can be improved. Further, by comparing the calculated shape of the wafer with the measurement data before the exclusion, it is possible to easily determine the defect of the outer peripheral edge of the wafer and the attached foreign matter.

[Notch judgment method]
The notch determination unit 15 determines, for example, the position of the notch 21 at the rotation stop position of the wafer 2 at the end of measurement based on the statistically calculated outer peripheral edge of the wafer 2 and the measurement data stored in the storage unit 12. In the example shown in FIG. 4, the position of the notch 21 is a value converted from the measurement reference position MesLine as the reference of the rotation axis of the measurement table 4 into the rotation angle (θn−Δθv).

  Here, since the notch 21 is a groove processed with a predetermined accuracy, in many cases it can be determined as a defect, which is an irregular element, by detecting the depth of the deep groove and the width along the outer periphery. is there.

  FIG. 8 is a diagram for explaining the notch determination process. In particular, FIG. 8A shows an example when a plurality of dents in the outer edge are detected, and FIG. 8B shows the center point of the notch 21. FIG. Hereinafter, the notch determination processing by the notch determination unit 15 will be described with reference to FIG.

  The notch determination unit 15 converts the calculation result by the statistical calculation unit 14 into data on the outer peripheral edge of the wafer 2 without eccentricity. The notch determination unit 15 determines the depth of the predetermined deep groove (first deep groove dp #) based on the radius (center Cw) of the ellipse 2Q calculated from the least square method and the data of the outer peripheral edge of the wafer 2 without eccentricity. A dent based on 1) is detected. For example, the first deep groove dp # 1 has a recess of 300 μm or more. Specifically, as shown in FIG. 8A, the notch determination unit 15 determines the notch 21 with the first deep groove dp # 1 as a reference, for example, in the following process.

(1) When the notch determination unit 15 detects one dent in the first deep groove dp # 1 or more, the notch determination unit 15 performs the following processing as shown in FIG.
(A) A location having the smallest radius among the detected dents is set as a temporary notch center point.
(B) A portion having a minimum radius +10 μm (= r _min + Δrd) from the center point of the temporary notch is detected.
(C) The middle point of the coordinates detected on the left and right is set as the center point of the notch 21, and the notch 21 is processed as 0 degree in the next step. This completes the notch determination process. In the next process, the notch reference is used, so the direction of the notch 21 is always the same direction (Ref reference).

(2) When the notch determination unit 15 detects two or more dents, the notch determination condition is made stricter, and the second deep groove dp # 2 (the dent is 400 μm or more) deeper than the first deep groove dp # 1. Redo detection.
When only one dent is detected, the process proceeds to (A) to (C).

(3) When the notch determination unit 15 detects a dent at a plurality of locations, the notch determination condition is further tightened, and the third deep groove dp # 3 (the dent is 500 μm or more) deeper than the second deep groove dp # 2. Redo detection with.
When only one dent is detected, the process proceeds to (A) to (C).

  (4) The notch determination unit 15 outputs a warning as an abnormality of the wafer 2 when a plurality of recesses are found in the third deep groove dp # 3 (the recess of 500 μm or more). The next process is not executed, and the wafer 2 is returned to the original position.

(5) Further, when the notch determination unit 15 cannot detect the dent in the first deep groove dp # 1 or more, the notch determination unit 15 relaxes the notch determination condition and sets a predetermined shallow groove (first shallow groove sh #). 1) The above dent is detected. For example, the first shallow groove sh # 1 has a recess of 200 μm or more, and the detection of the notch 21 is repeated in the first shallow groove sh # 1.
When the dent is detected, the process proceeds to (A) to (C).
If the dent cannot be detected, the notch determination condition is further relaxed, and the dent is detected again with the second shallow groove sh # 2 (the dent of 100 μm or more).

(6) When the notch determination unit 15 detects a dent in the second shallow groove sh # 2 or more, the notch determination unit 15 proceeds to the processes (A) to (C).
The notch determination unit 15 outputs a warning as a notch error of the wafer 2 when the dent cannot be detected. The next process is not executed, and the wafer 2 is returned to the original position.

  FIG. 9 shows an example of the centering result of the wafer 2. In addition, it is a figure which shows the outer periphery edge of the wafer 2 seen from the downward direction (bottom surface). In the example of FIG. 9, the wafer 2 is placed on the basis of the position of the notch 21 being 0 degree.

  In addition, as described below, the effective data group extraction unit 13, the statistical calculation unit 14, and the notch determination unit 15 described above make the sides of the outer peripheral edge of the wafer 2 (sides with high priority of the effective data group and other sides). ), A part caused by irregular elements such as a foreign substance, and a part of the side defined as the notch 21 (including a notch error warning).

(Valid data group)
Priority 1) L # 5: First (longest no foreign matter / deletion) long continuous data edge priority 2) L # 7: Second longest continuous data edge priority 3) L # 3: Third Long continuous data edge (excluded data)
L # 1: Side of continuous data excluded from ellipse calculation L # 6: Side of continuous data where foreign matter is continuous L # 2, L # 8: Portion determined as foreign matter (notch determination)
L # 4: The portion determined as the notch 21 As described above, the position of the notch 21 can be detected even if dust adheres to the outer peripheral edge portion of the wafer 2 or there is a missing portion. The center Cw of the shaped wafer 2 can be accurately detected.

  The adjustment data notifying unit 16 sends adjustment data including these pieces of information to the polishing table 8 based on the amount and direction of eccentricity of the wafer 2 and the position of the notch 21 obtained by the statistical calculation unit 14 and the notch determination unit 15. Notice. In the polishing table 8, the polishing table rotation shaft 81 is moved using the adjustment data so that the center Cw of the wafer 2 and the rotation center on the table on which the wafer 2 is placed coincide with each other.

  FIG. 10 is a diagram illustrating an example of a wafer positioning result on the polishing table 8. As shown in FIG. 10, in the polishing table 8, the center Cw of the wafer 2 and the rotation center of the polishing table 8 are aligned, and the center point of the notch 21 is aligned along the Ref reference (0 degree).

  The input / output setting unit 17 acquires various setting data input from the input / output device, measurement data output to the input / output device, and the like, and performs setting in the arithmetic device 10 and data output to the input / output device.

  FIG. 11 shows an example of setting data for the arithmetic device 10. The parameters 121 shown in FIG. 11 include the reference position for setting the laser measurement unit 5 as described above, the distance between the laser measurement unit 5 and the rotation center of the measurement table 4, the comparison angle interval Δθd, the threshold value Δrth, for each wafer diameter. The number of effective extraction data groups (the number extracted preferentially from the top) and the like are stored in the storage unit 12 in advance. These can be updated as appropriate.

  According to the wafer positioning detection apparatus 1 of the embodiment as described above, for example, an error is several tens of microns (conventional apparatus) by using an effective data group extraction process and an ellipse arithmetic expression (for example, the least square method).・ Accuracy can be increased to several microns on the order of method. Further, since the outer peripheral edge of the wafer 2 can be derived from the elliptic equation, foreign matters and defects can be easily determined from the acquired measurement data.

  As described above, according to the wafer positioning detection apparatus of the embodiment, it is possible to extract the measurement data that can calculate the accurate radius of the wafer from the measurement data with respect to the outer peripheral edge of the wafer and accurately calculate the center of the wafer. .

(Explanation of flowchart)
FIG. 12 is a flowchart of wafer positioning detection processing mainly used in the wafer positioning detection apparatus 1 of FIG. FIG. 13 is a flowchart showing details of the wafer radius measurement process of FIG. FIG. 14 is a flowchart showing details of the valid data group determination process of FIG. 12, and FIG. 15 is a flowchart showing details of the notch determination process of FIG. FIG. 16 is a flowchart showing the continuation of the details of the notch determination processing of FIG.

[Overall process flow]
After the main power supply of the wafer positioning detection device 1 is turned on, after a startup process or the like, for example, when a notification that the wafer 2 can be placed on the measurement table 4 is received from the transfer rail 6, the subsequent processes including the wafer positioning detection process are included. Processing begins.

  The wafer positioning detection device 1 places the wafer 2 on the measurement table 4 via the transfer arm 3 and the transfer rail 6 (step S1).

  Next, the wafer positioning detection apparatus 1 proceeds to the wafer radius measurement process (step S2). The wafer radius measurement process will be described later in detail.

  Next, the wafer positioning detection apparatus 1 proceeds to a valid data group determination process (step S3). The valid data group determination process will be described later in detail.

  Next, the wafer positioning detection apparatus 1 extracts a valid data group having a high priority from the valid data group (step S4).

  Next, the wafer positioning detection device 1 calculates the outer peripheral edge of the wafer 2 by the least square method for obtaining the ellipse 2Q based on the extracted effective data group (step S5).

  Next, the wafer positioning detection device 1 obtains the center Cw of the wafer 2 using the calculated ellipse 2Q, and calculates the amount of eccentricity and the direction of eccentricity from the rotation center Or with respect to the center Cw (step S6).

  Next, the wafer positioning detection device 1 proceeds to a notch determination process (step S7). The notch determination process will be described later in detail.

  Next, the wafer positioning detection apparatus 1 notifies the polishing table 8 of adjustment data including the position of the center Cw of the wafer 2 and the position of the notch 21 (step S8).

  Next, the wafer positioning detection device 1 transports the wafer 2 to the polishing table 8 which is a device for the next process (polishing process) via the transport rail 6 (step S9).

  Next, in the polishing process, the grindstone 7 polishes the wafer 2 placed on the polishing table 8 (step S10).

  Next, the polished wafer 2 is unloaded from the polishing table 8 to a predetermined position in the next process via the transfer arm 3 and the transfer rail 6 (step S11). After the end of step 11, this process ends.

[Wafer Radius Measurement Processing Flow]
The measurement data acquisition unit 11 sends an instruction to the laser measurement unit 5 to place it at a position corresponding to the wafer diameter among the reference positions Pos # 1 to # 3 (step S21).

  Next, the measurement data acquisition unit 11 sends a rotation start instruction to the measurement table 4 (step S22). In response to this start instruction, the rotation shaft 41 of the measurement table 4 starts rotating.

  Next, the measurement data acquisition unit 11 sequentially acquires measurement data including the rotation angle θi from the measurement table 4 and the wafer radius ri of the wafer 2 from the laser measurement unit 5 (step S23).

  The measurement data acquisition unit 11 checks whether the rotation angle θi has reached the measurement end angle (step S24).

  If the measurement end angle has not been reached (No in step S24), the process returns to step S23.

  When the measurement end angle is reached (Yes in step S24), the measurement data acquisition unit 11 sends a rotation stop instruction to the measurement table 4 (step S25).

  The measurement data acquisition unit 11 sends an instruction to the laser measurement unit 5 to return to the isolation position from the measurement table 4 (step S26). After the end of step S26, this process ends, and the process returns to the original processing destination.

[Valid data group judgment processing flow]
The valid data group extraction unit 13 acquires the wafer radius ri for each comparison angle interval Δθd from the measurement data stored in the storage unit 12 (step S31). For example, the first comparison start can be started by comparing the measurement start angle with the rotation angle θi separated from the comparison angle interval Δθd.

  Next, the valid data group extraction unit 13 obtains a difference in the wafer radius ri of the comparison angle interval Δθd for the acquired measurement data (step S32).

  Next, the valid data group extraction unit 13 determines whether or not the obtained difference is within a predetermined threshold Δrth (step S33).

  When the difference is within the predetermined threshold Δrth (Yes in step S33), the valid data group extraction unit 13 determines the acquired wafer radius ri of the rotation angle θi at the comparison angle interval Δθd as continuous data (step S34). . After the determination, the valid data group extraction unit 13 proceeds with the process to step S36.

  On the other hand, when the difference exceeds the predetermined threshold Δrth (No in step S33), the valid data group extraction unit 13 determines the wafer radius ri of the rotation angle θi at the acquired comparison angle interval Δθd as discontinuous data. (Step S35). After the determination, the valid data group extraction unit 13 proceeds with the process to step S36.

  Next, the valid data group extraction unit 13 determines whether the comparison by the comparison angle interval Δθd has reached the measurement end angle (step S36). For example, the end of the comparison ends with a comparison between the measurement end angle and the rotation angle θi separated from the comparison angle interval Δθd.

  When the measurement end angle is reached (Yes in step S36), the valid data group extraction unit 13 advances the process to step S37. On the other hand, when the measurement end angle has not been reached (No in step S36), the valid data group extraction unit 13 returns the process to step S31.

  Next, the valid data group extraction unit 13 extracts a chunk of continuous data, which is measurement data having a continuous rotation angle range, from the data determined as the continuous data for the wafer radius ri (step S37).

  Next, the valid data group extraction unit 13 assigns a higher priority to the extracted valid data group in order from the longest edge of the outer peripheral edge portion of the wafer 2 (step S38). After the end of step S38, this process ends and the process returns to the original processing destination.

[Notch determination processing flow]
The notch determination unit 15 acquires the outer periphery data of the wafer 2 based on the ellipse 2Q calculated by the statistical calculation unit 14 (step S71).

  The notch determination unit 15 detects a groove deeper than the reference first deep groove dp # 1 (step S72).

  The notch determination unit 15 determines whether or not a deep groove has been detected (step S73). When no deep groove can be detected (Yes in step S73), the notch determination unit 15 moves the process to step S710.

  On the other hand, when a deep groove is detected (No in step S73), the notch determination unit 15 determines the number of detection (step S74). When one deep groove is detected (Yes in step S74), the notch determination unit 15 moves the process to step S715.

  On the other hand, when two or more deep grooves are detected (No in step S74), the notch determination unit 15 uses the second deep groove dp # 2 deeper than the first deep groove dp # 1 as a reference and deeper grooves than that. Is detected (step S75).

  The notch determination unit 15 determines whether one groove deeper than the second deep groove dp # 2 has been detected (step S76). When two or more deep grooves are detected (No in step S76), the notch determination unit 15 moves the process to step S77. When one deep groove is detected (Yes in step S76), the notch determination unit 15 moves the process to step S715.

  The notch determination unit 15 detects a deeper groove with reference to the third deep groove dp # 3 deeper than the second deep groove dp # 2 (step S77).

  The notch determination unit 15 determines whether one groove deeper than the third deep groove dp # 3 has been detected (step S78). When two or more deep grooves are detected (No in Step S78), the notch determination unit 15 notifies the wafer abnormality to an external device or the like (Step S79). After the notification, the notch determination unit 15 ends this processing and returns the processing to the original processing destination.

  On the other hand, when one deep groove is detected (Yes in step S78), the notch determination unit 15 moves the process to step S715.

  Next, the notch determination unit 15 detects a groove deeper than the first shallow groove sh # 1, which is a groove shallower than the first deep groove dp # 1 (step S710).

  The notch determination unit 15 determines whether or not a deep groove has been detected (step S711). When a deep groove is detected (Yes in step S711), the notch determination unit 15 moves the process to step S715. On the other hand, if no deep groove can be detected (No in step S711), the notch determination unit 15 moves the process to step S712.

  Next, the notch determination unit 15 detects a groove deeper than the second shallow groove sh # 2, which is a groove shallower than the first shallow groove sh # 1 (step S712).

  The notch determination unit 15 determines whether or not a deep groove has been detected (step S713). When a deep groove is detected (Yes in step S713), the notch determination unit 15 moves the process to step S715. On the other hand, if no deep groove can be detected (No in step S713), the notch determination unit 15 moves the process to step S714.

  Next, the notch determination unit 15 notifies a notch error to an external device or the like (step S714). After the notification, the notch determination unit 15 ends this processing and returns the processing to the original processing destination.

  The notch determination unit 15 sets the position having the smallest radius in the detected deep groove as the temporary notch center point (step S715).

  Next, the notch determination unit 15 detects a location of “minimum radius + 10 μm” to the left and right from the temporary notch center point (step S716).

  Next, the notch determination unit 15 sets the midpoint of the part detected on the left and right as the center point of the notch 21 (step S717). After the end of step S717, the process ends and the process returns to the original processing destination.

[Hardware configuration of arithmetic unit]
FIG. 17 is a block diagram illustrating an example of a hardware configuration of the arithmetic device 10 illustrated in FIG. As illustrated in FIG. 17, the arithmetic device 10A includes, for example, a CPU (Central Processing Unit) 101, a ROM (Read Only Memory) 102, a RAM (Random Access Memory) 103, an HDD (Hard Disk Drive) 104, and a CD-ROM (Compact). Disk ROM) 105, keyboard 106, mouse 107, monitor 108, interface 109, and the like.

  The CPU 101 starts a boot process based on a startup program stored in the ROM 102 at the time of startup such as after power-on provided in the arithmetic device 10A. The ROM 102 is a memory that stores (stores) a startup program for the CPU 101 and the like.

  After startup, the CPU 101 reads an application (wafer positioning detection program) of the arithmetic device 10A from the HDD 104 or the CD-ROM 105, and stores the read application in the RAM 103 or the like. A RAM 103 is a main memory (storage device) of the CPU 101, and is used as a work area or the like in addition to the main memory when the CPU 101 executes an application. One application is a program that causes the CPU 101, the RAM 103, and the like to operate as the arithmetic device 10A.

  Specifically, the CPU 101, the RAM 103, etc. execute the processing of each means shown in FIG. 5 according to this application. Processing of each unit of the arithmetic device 10 shown in FIG. 5 is realized by an application installed and executed on the computer, and operates as the arithmetic device 10 by cooperating with hardware included in the computer.

  The HDD 104 is a hard disk device, and corresponds to, for example, the storage unit 12 shown in FIG. The HDD 104 stores, for example, basic data such as operating system (OS) software and browser software, various data such as measurement data, setting data related to the apparatus, and calibration data.

  The CD-ROM 105 is a drive device for reading an application, various data, and the like recorded on a CD-ROM medium. The CD-ROM 105 may be a drive device for reading other recording media such as a DVD (Digital Versatile Disk) or a USB memory (Universal Serial Busflash drive).

  The interface 109 enables access between a computer and a communication medium (wireless LAN, Internet, etc.) and access with a database device or the like. That is, the interface 109 realizes input / output data transfer between the computer and an external device.

  The keyboard 106 and the mouse 107 are used when an operator performs measurement menu selection, input operation, start operation, stop operation, etc. on the arithmetic device 10A as necessary. The monitor 108 is a display device used for confirming the display when confirming the operation state of the arithmetic device 10A, data input / parameter setting, measurement menu selection, or the like.

  The arithmetic device 10A may be connected to these devices as an external device via the interface 109 except for the CD-ROM 105, the keyboard 106, the mouse 107, the monitor 108, etc. from the arithmetic device 10A.

  As described above, according to the wafer positioning detection method of the present embodiment, the measurement data capable of calculating the accurate radius of the wafer is extracted from the measurement data with respect to the outer peripheral edge of the wafer, and the center of the wafer is accurately calculated. Can do.

  Further, according to the wafer positioning detection program of the present embodiment, measurement data capable of calculating an accurate radius of the wafer can be extracted from the measurement data with respect to the outer peripheral edge of the wafer, and the center of the wafer can be accurately calculated.

[Other Embodiments]
As mentioned above, although embodiment of this invention was described, this embodiment is shown as an example and is not intending limiting the range of invention. Further, for example, this embodiment can be implemented in various other forms, and various omissions, replacements, and changes can be made without departing from the gist of the invention. This embodiment and its modifications are included in the scope and gist of the invention, and are also included in the invention described in the claims and their equivalents.

  DESCRIPTION OF SYMBOLS 1 ... Wafer positioning detection apparatus 2, 2a, 2b, 2c ... Wafer, 2Q ... Ellipse, 3 ... Transfer arm, 4 ... Measurement table, 5 ... Laser measurement unit, 6 ... Transfer rail, 7 ... Grinding stone, 8 ... Polishing table DESCRIPTION OF SYMBOLS 10, 10A ... Calculation apparatus, 11 ... Measurement data acquisition part, 12 ... Memory | storage part, 13 ... Effective data group extraction part, 14 ... Statistical calculation part, 15 ... Notch determination part, 16 ... Adjustment data notification part, 17 ... On Output setting unit, 20 ... ingot, 21 ... notch, 22 ... circular wafer, 31 ... suction unit, 32 ... lift arm, 41 ... rotating shaft, 51 ... laser projector, 52 ... laser receiver, 53 ... laser beam, 81: Polishing table rotating shaft, 101: CPU, 102: ROM, 103: RAM, 104: HDD, 105: CD-ROM, 106: Keyboard, 107: Mouse, 108 Monitor, 109 ... interface, 121 ... parameter 211 ... deposits, 212 ... defect, 213 ... large deposits

Claims (8)

A wafer positioning detection device for detecting the center of a substantially disk-shaped wafer having a notch at an outer peripheral edge,
A measurement table on which the wafer is placed and rotated while holding the rotation center of the wafer and the axis center of the rotation axis together, and the rotation angle of the rotation axis can be measured,
The wafer can be placed in the vicinity of the outer peripheral edge of the mounted wafer while maintaining a predetermined distance from the measurement table, and irradiated with laser light in a direction perpendicular to the substantially disk-shaped surface of the wafer. A laser measurement unit that receives and measures laser light to measure the distance to the outer peripheral edge of the wafer;
An arithmetic unit that calculates a wafer radius from the rotation center of the wafer to an outer peripheral edge of the wafer and an eccentric amount and an eccentric direction from the rotation center with respect to the center of the wafer;
The outer diameter of the measurement table is formed smaller than the outer diameter of the wafer, the measurement table is rotated by the laser measurement unit so that the distance from the outer peripheral edge of the wafer over the entire circumference of the wafer can be measured,
The arithmetic unit is
A measurement data acquisition unit for acquiring measurement data including the wafer radius calculated from the rotation angle and the distance between the laser measurement unit measured for each rotation angle and the outer peripheral edge of the wafer;
A storage unit for storing the measurement data acquired by the measurement data acquisition unit;
For the wafer radius stored in the storage unit, it is determined whether or not the difference in the wafer radius at the rotation angle is within a predetermined threshold at every predetermined comparison angle interval, and in a continuous rotation angle range. An effective data group extraction unit that extracts, as an effective data group, the measurement data determined that all the wafer radii are within the predetermined threshold;
Statistically calculating the outer peripheral edge of the wafer based on the elliptic equation using the extracted effective data group, and calculating the eccentric amount and the eccentric direction based on the statistically calculated outer peripheral edge; A wafer positioning detection device comprising: The effective data group extraction unit prioritizes an effective data group having a longer arc length in each measurement section from the extracted effective data group, and further extracts the effective data group up to a predetermined priority order. The wafer positioning detection device according to claim 1, wherein the statistical calculation unit is used. The measurement data acquisition unit has an overlap section in which the measurement range for the entire circumference of the wafer has an overlap section for measuring from the measurement start angle to a certain angle range until reaching the measurement end angle. The wafer positioning detection device according to claim 1, wherein the wafer positioning detection device is obtained. The arithmetic unit is
The apparatus further comprises a notch determination unit that determines the position of the notch based on a reference groove depth from the outer peripheral edge of the wafer that has been statistically calculated and the measurement data stored in the storage unit. The wafer positioning detection apparatus according to any one of claims 1 to 3. 5. The wafer positioning detection apparatus according to claim 1, wherein the statistical calculation unit statistically calculates an outer peripheral edge of the wafer by using a least-square method for the elliptic equation. 6. The arithmetic unit is
Based on the amount of eccentricity and the direction of eccentricity, adjustment data relating to the center of the wafer is adjusted so that the center of the wafer coincides with the rotation center of the next process table for mounting the wafer in the next process. The wafer positioning detection device according to any one of claims 1 to 5, further comprising an adjustment data notification unit that notifies the device. A wafer positioning detection method comprising a measurement table and a laser measurement unit, and used in a wafer positioning detection device for detecting a center of a wafer by placing a substantially disk-shaped wafer having a notch at an outer peripheral edge on the measurement table,
The outer diameter of the measurement table is formed smaller than the outer diameter of the wafer,
The wafer positioning detection device has the following steps:
A rotation measurement step of measuring the rotation angle of the rotation axis by rotating the measurement table while holding the rotation center of the wafer placed and the axis center of the rotation axis of the measurement table;
The laser measurement unit emits laser light in the direction perpendicular to the substantially disk-shaped surface of the wafer in the vicinity of the outer peripheral edge of the mounted wafer, and the irradiated laser light is received and measured to measure the rotation center of the wafer. And a distance measuring step for measuring a wafer radius to the outer peripheral edge of the wafer,
Based on the wafer radius measured by the distance measurement step, an operation step for calculating an eccentric amount and an eccentric direction from the rotation center with respect to the center of the wafer,
The calculation step further includes:
A measurement data acquisition step for acquiring measurement data including the rotation angle, and the wafer radius measured by the distance measurement step for each rotation angle;
A storage step of storing the measurement data acquired by the measurement data acquisition step;
A threshold determination step for determining whether or not a difference in the wafer radius at the rotation angle is within a predetermined threshold at a predetermined comparison angle interval for the stored wafer radius;
An effective data group extraction step of extracting, as an effective data group, the measurement data in which all the wafer radii in a continuous rotation angle range are determined to be within the predetermined threshold;
Using the extracted effective data group, statistically calculating the outer peripheral edge of the wafer based on an elliptic equation, and calculating the eccentric amount and the eccentric direction based on the statistically calculated outer peripheral edge; A wafer positioning detection method comprising: Computer
A measurement table and a laser measurement unit are provided, and an approximately disk-shaped wafer having a notch at the outer peripheral edge is placed on the measurement table to detect the center of the wafer. The outer diameter of the measurement table is larger than the outer diameter of the wafer. A wafer positioning detection program that operates as a small wafer positioning detection device,
A rotation measurement step of measuring the rotation angle of the rotation axis by rotating the measurement table while holding the rotation center of the wafer placed and the axis center of the rotation axis of the measurement table;
The laser measurement unit emits laser light in the direction perpendicular to the substantially disk-shaped surface of the wafer in the vicinity of the outer peripheral edge of the mounted wafer, and the irradiated laser light is received and measured to measure the rotation center of the wafer. And a distance measuring step for measuring a wafer radius to the outer peripheral edge of the wafer,
A calculation step of calculating an eccentric amount and an eccentric direction from the rotation center with respect to the center of the wafer based on the wafer radius measured by the distance measurement step;
The calculation step further includes:
A measurement data acquisition step for acquiring measurement data including the rotation angle, and the wafer radius measured by the distance measurement step for each rotation angle;
A storage step of storing the measurement data acquired by the measurement data acquisition step;
A threshold determination step for determining whether or not a difference in the wafer radius at the rotation angle is within a predetermined threshold at a predetermined comparison angle interval for the stored wafer radius;
An effective data group extraction step of extracting, as an effective data group, the measurement data in which all the wafer radii in a continuous rotation angle range are determined to be within the predetermined threshold;
Using the extracted effective data group, statistically calculating the outer peripheral edge of the wafer based on an elliptic equation, and calculating the eccentric amount and the eccentric direction based on the statistically calculated outer peripheral edge; A wafer positioning detection program comprising:

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