JP2011040637A - Detecting method, wafer carrying-in method, and detecting device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To speedily detect a position of a different-shape part formed at an outer peripheral end of a wafer. <P>SOLUTION: A detecting method includes acquiring a position of the outer peripheral end within an imaging range of an imaging camera 93 as imaging data by imaging the imaging range during a stop of a rotary stage 911, mounted with the wafer whose outer peripheral edge formed of an arc part and the different-shape part, while rotating the rotary stage 911 intermittently at each predetermined angle, and also acquiring position change of the outer peripheral end passing through the imaging range of the imaging camera 93 during rotation of the rotary stage 911 as measurement data. Then positions on the arc part of the wafer are selected from the imaging data, and reference data is generated which represents position change within the imaging range when positioned on the entire circumference of the circle including the arc part are positioned within the imaging range for each angle of rotation of the rotary stage 911. Then the measurement data is compared with the reference data to detect the position of the different-shape part. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a detection method, a wafer carry-in method, and a detection apparatus that detect irregularly shaped portions formed on the outer peripheral edge of a wafer.

  In a semiconductor device manufacturing process, a wafer on which a device such as an IC or LSI is formed on the front surface is ground and polished on the back surface before being divided into individual chips and processed to a predetermined thickness. For example, Patent Document 1 includes a polishing apparatus that includes an index table in which four chuck tables are arranged, and that can simultaneously polish wafers held on two chuck tables positioned in a polishing region on the index table. It is disclosed.

  By the way, the outer shape of the wafer has a substantially circular shape, and an abnormally shaped portion such as an orientation flat or a notch showing a normal crystal orientation is formed at the outer peripheral end thereof. This irregularly shaped portion is, for example, a notched portion in which a part of the outer peripheral end is notched in the radial direction of the wafer, and the irregularly shaped portion is detected in the apparatus for grinding and polishing a wafer as described above. Those with functions are also known.

  Here, the conventional method for detecting the irregularly shaped portion will be briefly described. First, a wafer is placed on a rotary stage. Next, the outer peripheral edge of the wafer is imaged while rotating the wafer on the rotary stage, and the center of the wafer (center of the circle including the arc portion of the wafer) is calculated based on the obtained imaging data. Then, after aligning the center of the wafer with the rotation axis of the rotary stage, the position of the irregularly shaped portion is detected by imaging the outer peripheral edge while rotating the wafer on the rotary stage again. In detail, since the arc portion occupies most of the outer peripheral end of the wafer, the position where the outer peripheral end is greatly deviated from the circumference of the circle including the arc portion is detected and set as the position of the irregular shape portion.

Japanese Patent Laid-Open No. 10-086048

  However, in the conventional method for detecting the irregularly shaped portion described above, it is necessary to make the center of the wafer coincide with the rotation axis of the rotary stage prior to detecting the irregularly shaped portion. For this reason, the outer peripheral edge of the wafer has to be imaged at least twice in order to calculate the center of the wafer and to detect the irregularly shaped portion, and there is a problem that it takes a long time to detect the irregularly shaped portion. .

  The present invention has been made in view of the above, and provides a detection method, a wafer carry-in method, and a detection apparatus that can quickly detect the position of the irregularly shaped portion formed on the outer peripheral edge of the wafer. Objective.

  In order to solve the above-described problems and achieve the object, a detection method according to the present invention includes: placing a wafer having an outer peripheral end made up of an arc portion and an irregularly shaped portion on a rotary stage; A placement step of positioning a part of the end within the imaging range of the imaging camera; and imaging the imaging range by the imaging camera in a state where the rotary stage is stopped at a predetermined rotation angle that is predetermined as a stop rotation angle; An imaging data acquisition step for acquiring, as imaging data, the position of the outer peripheral edge of the wafer at the stop rotation angle positioned within the imaging range, and the imaging by the imaging camera while rotating the rotary stage to the next stop rotation angle. A range of images of the wafer passing through the imaging range as the rotary stage rotates between the stop rotation angles. An actual measurement data acquisition step for acquiring a change in position of the peripheral edge as actual measurement data, a rotation determination step for determining whether or not to end the rotation of the rotary stage, and a determination to end the rotation of the rotary stage in the rotation determination step Until the imaging data acquisition step, the actual measurement data acquisition step and the rotation determination step are repeatedly performed, and the arc from the position of the outer peripheral edge at the stop rotation angle acquired as the imaging data An arc portion position selecting step for selecting a position on a portion, and a position of the entire circumference of a circle including the arc portion based on the position on the arc portion selected in the arc portion position selecting step A reference data creation step of creating reference data representing a position change in the imaging range when positioned in the range for each rotation angle of the rotary stage; Characterized in that it comprises a a different shape portion detection step of detecting a position of the irregular-shaped portion by comparing the change in position of the outer peripheral edge of the wafer which is obtained as the measured data and the reference data.

  The detection method according to the present invention is characterized in that, in the above invention, the center of a circle including the arc portion is calculated based on the position on the arc portion selected in the arc portion position selecting step. To do.

  Further, in the detection method according to the present invention, in the above invention, the arc portion position selecting step divides the imaging data into a plurality of sets each including at least three sets, and the outer edge of the imaging data for each set. A temporary center calculation step of calculating the center of a circle determined by the position of the virtual center as a temporary center, comparing each temporary center calculated for each of the plurality of sets, and sequentially calculating a predetermined number from the temporary center that is farthest from other temporary centers. The position of the outer peripheral edge of the imaging data of each set excluding the set used to calculate the excluded temporary center is selected as the position on the arc part, and the predetermined number is the size of the irregularly shaped part And an angle interval between the stop rotation angles is set in advance.

  In the detection method according to the present invention as set forth in the invention described above, the irregular shape detection step calculates a difference value for each rotation angle between the change in position of the outer peripheral edge of the wafer acquired as the actual measurement data and the reference data. Then, the position of the outer peripheral edge positioned in the imaging range is detected as the position of the irregularly shaped portion in a rotation angle range where the difference value exceeds a predetermined threshold value.

  Further, the wafer carrying-in method according to the present invention includes a holding unit having a holding surface for holding a wafer having an outer peripheral end composed of an arc portion and an irregular shape portion, and the wafer held on the holding surface of the holding unit. In a grinding apparatus comprising a grinding means for grinding, a wafer carrying-in method for carrying the wafer onto a holding surface of the holding means, wherein the wafer is placed on a rotating stage, and an outer peripheral edge of the wafer is A placement step of positioning a part within the imaging range of the imaging camera, and imaging the imaging range by the imaging camera in a state where the rotary stage is stopped at a predetermined rotation angle that is predetermined as a stop rotation angle. An imaging data acquisition step of acquiring, as imaging data, the position of the outer peripheral edge of the wafer at the stop rotation angle positioned in the rotation, and the rotation The imaging range is continuously imaged by the imaging camera while rotating the stage to the next stop rotation angle, and the outer peripheral edge of the wafer passes through the imaging range as the rotary stage rotates between the stop rotation angles. An actual measurement data acquisition step of acquiring a change in position as actual measurement data, a rotation determination step for determining whether or not to end the rotation of the rotary stage, and until the rotation determination step determines that the rotation of the rotary stage is to be ended Between the imaging data acquisition step, the actual measurement data acquisition step, and the rotation determination step, and the arc portion from the position of the outer peripheral edge at the stop rotation angle acquired as the imaging data. Circle calculation step of calculating the center of a circle including the arc portion based on the selected position on the arc portion Based on the position on the arc portion selected in the circle calculation step, the position change in the imaging range when the position of the entire circumference of the circle including the arc portion is positioned in the imaging range. A reference data creation step for creating reference data represented for each rotation angle of the rotation stage, and a position change of the outer peripheral edge of the wafer acquired as the actual measurement data is compared with the reference data to determine the position of the irregularly shaped portion. And detecting a deformed portion detecting step, a positioning step of aligning the center of a circle including the arc portion with the rotation center of the rotary stage, and the position of the deformed portion detected in the deformed portion detecting step. And a wafer holding step of holding the wafer on the holding surface in a predetermined direction.

  In addition, the detection apparatus according to the present invention is configured to rotatably mount an imaging camera and a wafer having an outer peripheral end formed of an arc portion and an irregularly shaped portion, and a part of the outer peripheral end of the wafer. A rotary stage positioned within the imaging range, and the imaging when the rotary stage is stopped at the stop rotation angle while intermittently rotating while the rotary stage is stopped at a predetermined rotation angle set as a stop rotation angle. The imaging range is imaged by the camera, the position of the outer peripheral edge of the wafer in the imaging range is acquired as imaging data, and the imaging range is continuously imaged by the imaging camera when the rotary stage is rotated, The position change of the outer peripheral edge of the wafer passing through the imaging range with the rotation of the rotary stage between the stop rotation angles. Data acquisition means for acquiring measurement data, arc position selection means for selecting a position on the arc from the position of the outer peripheral edge at the stop rotation angle acquired as imaging data, and the arc position selection means Based on the position on the arc portion selected by the above, the position change in the imaging range when the position of the entire circumference of the circle including the arc portion is positioned in the imaging range. Reference data creating means for creating reference data expressed for each angle, and a deformed portion for detecting the position of the deformed portion by comparing the change in position of the outer peripheral edge of the wafer acquired as the measured data with the reference data And a detecting means.

  According to the present invention, the position of the outer peripheral edge of the wafer positioned within the imaging range of the imaging camera when the rotary stage is stopped at the stop rotation angle while the rotary stage is stopped at the stop rotation angle. Can be acquired as measured data, and a change in the position of the outer peripheral edge of the wafer that passes through the imaging range of the imaging camera when the rotary stage rotates between stop rotation angles can be acquired as measured data. Then, the position on the arc portion is selected from the positions of the outer peripheral ends at the stop rotation angle as the imaging data, and the position of the entire circumference of the circle including the arc portion is imaged based on the position on the selected arc portion. It is possible to create reference data representing a change in position within the imaging range when positioned in the range for each rotation angle of the rotary stage. The position of the irregularly shaped portion can be detected by comparing the change in position of the outer peripheral edge of the wafer, which is actually measured data, with the reference data. According to this, since the position of the irregularly shaped portion can be detected by imaging the outer peripheral edge of the wafer at least once, the processing time can be shortened, and the position of the irregularly shaped portion formed on the outer circumferential edge of the wafer can be determined. It can be detected quickly.

FIG. 1 is a perspective view showing the back side of a wafer to be ground by a grinding apparatus. FIG. 2 is a perspective view showing a configuration example of a grinding apparatus. FIG. 3 is a perspective view for explaining the structure of the holding means constituting the grinding apparatus. FIG. 4 is an enlarged perspective view showing the periphery of the positioning means constituting the grinding apparatus. FIG. 5 is a side view for explaining the configuration of the positioning means. FIG. 6 is a flowchart showing an operation procedure of the grinding apparatus. FIG. 7 is a side view of the alignment means schematically showing the placing process. FIG. 8 is another side view of the positioning means schematically showing the placing process. FIG. 9 is an explanatory diagram illustrating an imaging data acquisition process, an actual measurement data acquisition process, and a rotation determination process. FIG. 10 is an explanatory diagram for explaining the circle calculation step. FIG. 11 is another explanatory diagram for explaining the circle calculating step. FIG. 12 is another explanatory diagram for explaining the circle calculation step. FIG. 13 is a diagram illustrating an example of the reference data. FIG. 14 is an explanatory diagram for explaining the deformed portion detection step. FIG. 15 is a side view of alignment means schematically showing the alignment of the center of the wafer. FIG. 16 is an explanatory diagram for explaining a modification of the direction alignment. FIG. 17 is an explanatory view illustrating a modified example of the wafer holding process after the direction alignment. FIG. 18 is an explanatory view illustrating a modification of the grinding process. FIG. 19 is a perspective view showing the back side of a wafer ground by a grinding apparatus of a modification. FIG. 20 is a perspective view showing another example of the irregularly shaped portion.

  Hereinafter, embodiments for carrying out a detection method, a wafer carry-in method and a detection apparatus according to the present invention will be described with reference to the drawings. In the present embodiment, a grinding apparatus to which the detection method, wafer carry-in method, and detection apparatus of the present invention are applied is exemplified.

  First, a wafer to be ground by the grinding apparatus exemplified in this embodiment will be described. FIG. 1 is a perspective view showing a back surface 21 side of a wafer 20 to be ground by a grinding apparatus. As shown in FIG. 1, the wafer 20 has a substantially circular outer shape. The arc portion 22 occupies most of the wafer 20, and an orientation flat 23, which is an example of an irregularly shaped portion that connects the ends of the arc portion 22 with straight lines. Have On the surface side of the wafer 20, a plurality of devices 24 partitioned vertically and horizontally as shown by broken lines in FIG. The grinding apparatus grinds the back surface 21 side while holding the front surface side of the wafer 20 on a predetermined holding surface. The orientation flat 23 indicates the crystal orientation of the wafer 20.

  Here, for example, when the wafer 20 is ground to a thickness of 50 μm or less, the wafer 20 is likely to warp. For this reason, the grinding process by the grinding apparatus is performed in a state where the entire surface of the wafer 20 is sucked and held by the holding surface having an outer shape substantially matching the wafer 20 so that the wafer 20 does not warp. In order to attract and hold the entire surface of the wafer 20 by such a holding surface, the position of the orientation flat 23 is detected, and the position of the orientation flat 23 corresponds to a position within the holding surface (for example, holding a deformed portion described later). It is necessary to carry the wafer 20 onto the holding surface in a direction that matches the position. Therefore, the grinding apparatus according to the present embodiment carries the front side of the wafer 20 onto the holding surface and detects the position of the orientation flat 23 before grinding the back side 21.

Specific examples of the wafer are not particularly limited. For example, silicon wafers, semiconductor wafers such as GaAs, ceramics, glass, sapphire (Al ₂ O ₃ ) -based inorganic material substrates, ductility such as plate metals and resins, etc. Material, and flatness on the order of micron to submicron (TTV: total thickness variation: the maximum and minimum values of the height of the entire wafer measured in the thickness direction with the back surface 21 being the ground surface of the wafer as the reference surface Various processing materials that require a difference between the two.

  Next, the grinding apparatus will be described. FIG. 2 is a perspective view illustrating a configuration example of the grinding apparatus 1 according to the present embodiment. FIG. 3 is a perspective view for explaining the configuration of the holding means 6a constituting the grinding apparatus 1. FIG. 4 is an enlarged perspective view showing the periphery of the positioning means 9 constituting the grinding apparatus 1, and FIG. 5 is a side view for explaining the configuration of the positioning means 9.

  As shown in FIG. 2, the grinding apparatus 1 includes, for example, a housing 2, two grinding means 3, 4, for example, three holding means 6 a to 6 c installed on the turntable 5, and cassettes 7, 8. , Positioning means 9, carry-in means 10, carry-out means 11, cleaning means 12, carry-in / out means 13, data acquisition means, arc portion position selection means, reference data creation means, and irregular shape part detection means The control means 19 is mainly provided.

  The surface of the grinding means 3 is adsorbed on the holding surface 6s while rotating a grinding wheel 3c having a grinding wheel 3b removably attached to the lower end of a rotating shaft 3a orthogonal to the holding surface 6s of the holding means 6b by a motor 3d. A predetermined grinding process (for example, rough grinding) is performed on the back surface 21 of the wafer 20 by pressing the back surface (upper surface) 21 of the wafer 20 to be held. Similarly, the grinding means 4 has a surface on the holding surface 6s while rotating a grinding wheel 4c having a grinding wheel 4b detachably attached to the lower end of a rotating shaft 4a orthogonal to the holding surface 6s of the holding means 6c by a motor 4d. A predetermined grinding process (for example, finish grinding) is applied to the back surface 21 of the wafer 20 by pressing the back surface 21 of the wafer 20 on which the side is sucked and held.

  These grinding means 3 and 4 are provided so as to be moved up and down by the lifting and lowering feeding means 15 and 16, respectively. The grinding wheels 3c and 4c having the grinding wheels 3b and 4b are adsorbed on the holding surface 6s of the holding means 6b and 6c. The rear surface 21 of the wafer 20 to be held is configured to be capable of grinding feed. These elevating and feeding means 15 and 16 are mounted on movable blocks 17 and 18 provided on the upper surface of the housing 2. The movable blocks 17 and 18 are movably provided with respect to the housing 2 by a moving mechanism (not shown) so that the grinding wheels 3c and 4c move forward and backward in the radial direction of the turntable 5 at positions near the holding means 6b and 6c. ing.

  The three holding means 6a to 6c on the turntable 5 are arranged at equal intervals with a phase angle of 120 degrees, for example. These holding means 6a to 6c have a chuck table structure having a vacuum chuck on the upper surface, and have a holding surface 6s formed flat. Further, these holding means 6a to 6c are rotationally driven in a horizontal plane by a rotational drive mechanism (not shown) at the time of grinding.

  The turntable 5 is provided on the upper surface of the housing 2 so as to be rotatable in a horizontal plane, and is driven to rotate at an appropriate timing. Then, the turntable 5 rotates the three holding means 6a to 6c by the grinding means 3 (position of the holding means 6b in FIG. 1) and the grinding position by the grinding means 4 (holding means in FIG. 1). 6c) and a carry-in / carry-out position (position of the holding means 6a in FIG. 1).

  Here, the configuration of the holding means 6a to 6c on the turntable 5 will be described with reference to FIG. FIG. 3 shows the wafer 20 which is carried onto the holding surface 6s of the holding means 6a by the carrying-in means 10 to be described later, together with the holding means 6a located at the carry-in / out position. Although the holding means 6a will be described here, the holding means 6b and 6c are configured similarly.

  As shown in FIG. 3, the holding means 6a includes a suction holding portion 61, and the upper surface of the suction holding portion 61 constitutes the central portion of the holding surface 6s. As described above, the outer peripheral end of the wafer 20 to be ground by the grinding apparatus 1 of the present embodiment is constituted by the arc portion 22 that occupies most and the orientation flat 23 that connects the ends of the arc portion 22 with straight lines. Has been. On the other hand, the upper surface of the suction holding unit 61 has an outer shape that substantially matches the outer shape of the wafer 20, and an irregularly shaped portion holding position 611 on which the orientation flat 23 is placed is formed.

  Although details will be described later, the wafer 20 has the back surface 21 on the holding surface 6s of the holding means 6a configured as described above in such a direction that the orientation flat 23 is placed at the irregular shape portion holding position 611 on the suction holding portion 61. It is carried up by the carrying-in means 10 and placed on the suction holding unit 61. The suction holding unit 61 is thus carried onto the holding surface 6s and holds the entire surface of the wafer 20 placed on the suction holding unit 61 by vacuum suction. For example, the suction holding unit 61 is made of porous ceramics or the like, and sucks and holds the entire surface of the wafer 20 placed on the upper surface by a suction mechanism (not shown).

  Returning to FIG. 2, the cassettes 7 and 8 are wafer containers having a plurality of slots. One cassette 7 accommodates the wafer 20 before grinding, and the other cassette 8 accommodates the wafer 20 after grinding.

  The alignment unit 9 includes a rotary adsorption unit 91, an auxiliary adsorption unit 92, and an imaging camera 93. The rotary suction means 91 is the center of the wafer 20 taken out from the cassette 7 by the carry-in / out means 13 and placed on the rotary stage 911 of the rotary suction means 91 (the center of a circle including the arc portion 22; Is expressed as “Wo”), and is used to detect the position of the orientation flat 23 to perform center alignment and direction alignment of the wafer 20. This alignment means 9 cooperates with the control means 19 and functions as a detection device.

  As shown in FIGS. 4 and 5, the rotary suction means 91 includes a rotary stage 911 including a first suction surface 911a that partially sucks the vicinity of the center of the surface of the wafer 20, and a perpendicular to the first suction surface 911a. A suction surface rotation driving unit 913 that rotates the rotary stage 911 with the shaft serving as a rotation shaft 912, and the rotation stage 911 in a predetermined direction along the surface direction of the first suction surface 911a according to the guide groove 914 (the formation direction of the guide groove 914) And a suction surface advancing / retreating drive unit 915 that linearly moves back and forth. The suction surface rotation drive unit 913 detects the rotation angle of the rotation stage 911 by an encoder (not shown), and is configured to be able to rotate the rotation stage 911 for each arbitrary angle.

  The auxiliary suction means 92 is spaced apart at a predetermined position in accordance with the moving direction of the rotary stage 911, and a second part that sucks a portion different from the vicinity of the central portion where the first suction surface 911a of the wafer 20 is sucked. The auxiliary suction stage 921 including the suction surface 921a is provided. The second suction surface 921a is set to the same height as the first suction surface 911a.

  The imaging camera 93 is disposed below the auxiliary suction means 92 at a predetermined position in accordance with the moving direction of the rotary stage 911 described above, and is one of the outer peripheral ends of the wafer 20 sucked and held on the rotary stage 911. This is for capturing an image of a part and acquiring its position information. The imaging camera 93 is constituted by a CCD line sensor, for example, and is connected to an acquisition data storage unit 931 as shown in FIG. The acquired data storage unit 931 is a memory for temporarily storing imaging data and actual measurement data captured by the imaging camera 93 as described later. The imaging data and actual measurement data stored in the acquired data storage unit 931 are read by the control unit 19 and used to calculate the center Wo of the wafer 20 and detect the position of the orientation flat 23.

  As shown in FIG. 4, the carry-in means 10 includes a support shaft 101 that freely moves up and down in the vertical direction and rotates about a vertical line passing through its base end portion as a central axis, and an upper end of the support shaft 101. A transfer arm unit 102 having one end side disposed thereon, and a suction pad 103 configured to suck and hold the wafer 20 is disposed on the other end side of the transfer arm unit 102. The transfer arm unit 102 has a first arm 102a whose one end is connected to the support shaft 101, one end connected to the other end of the first arm 102a, and a long axis direction of the first arm 102a from the other end of the first arm 102a. The suction arm 103 is attached to the other end of the second arm 102b. In the loading means 10, the suction pad 103 moves between the positioning means 9 and the holding means 6 a positioned at the loading / unloading position by the rotation of the transfer arm unit 102. Then, the back surface 21 of the wafer 20 before grinding, which has been aligned by the alignment means 9 by the suction pad 103, is sucked and held and carried onto the holding surface 6s of the holding means 6a located at the carry-in / out position. Further, the carry-in means 10 has a configuration in which the suction pad 103 can be expanded and contracted along the long axis direction of the first arm 102a by extending and contracting the second arm 102b with respect to the first arm 102a.

  Returning to FIG. 2, the unloading means 11 is connected at one end to a support shaft 111 that freely moves up and down in the vertical direction and rotates around a vertical line passing through its base end, and an upper end of the support shaft 111. And a suction pad 113 for sucking and holding the wafer 20 is attached to the other end of the transfer arm 112. The unloading means 11 sucks and holds the back surface 21 of the wafer 20 after grinding on the holding means 6 a located at the loading / unloading position, and unloads it to the cleaning means 12.

  The cleaning unit 12 cleans the wafer 20 after grinding, and removes contamination such as grinding dust adhering to the ground back surface 21.

  The carry-in / out means 13 is, for example, a robot pick provided with a U-shaped hand 13a. The U-shaped hand 13a sucks and holds the wafer 20 and transports it. Specifically, the loading / unloading means 13 unloads the wafer 20 before grinding from the cassette 7 to the positioning means 9 and places it on the rotary stage 911, and removes the wafer 20 after grinding from the cleaning means 12. Carry in cassette 8.

  The control means 19 is constituted by a microcomputer or the like, and controls the operation of each part constituting the grinding apparatus 1 to control the grinding apparatus 1 in an integrated manner. In the present embodiment, the control unit 19 reads out and uses the imaging data and the actual measurement data captured by the imaging camera 93 and stored in the acquired data storage unit 931, and before the grinding process placed on the rotary stage 911. A process for calculating the center Wo of the wafer 20 and detecting the position of the orientation flat 23 is performed.

  Next, the operation of the grinding apparatus 1 will be described with reference to FIGS. Here, FIG. 6 is a flowchart showing an operation procedure of the grinding apparatus 1 in the present embodiment. The grinding apparatus 1 implements the detection method by performing each process from step S1 to step S15 in FIG. Moreover, the grinding apparatus 1 implements the wafer carrying-in method by performing each process from step S1 to step S17 in FIG. In addition, operation | movement of the grinding apparatus 1 demonstrated below is implement | achieved when the control means 19 controls each part of an apparatus.

  As shown in FIG. 6, the grinding apparatus 1 according to the present embodiment first places the wafer 20 before grinding on the rotating stage 911 of the positioning means 9 as the placing step, A part is positioned in the imaging range of the imaging camera 93 (step S1).

  7 and 8 are side views of the positioning means 9 schematically showing the placing process. In this placement step, first, under the control of the control means 19, the carry-in / out means 13 takes out the wafer 20 before grinding from the cassette 7 by the U-shaped hand 13a and carries it out to the alignment means 9, and FIG. As shown in FIG. 5, the wafer 20 is placed on the rotary stage 911. At this time, the wafer 20 is placed on the rotary stage 911 so that the back surface 21 is on the upper side. Subsequently, the control means 19 drives the rotary stage 911 to suck and hold the surface of the wafer 20 by the first suction surface 911a. Note that the center Wo of the wafer 20 only needs to be positioned at the approximate center of the rotary stage 911 and may be offset from the rotary shaft 912.

  Thereafter, the control unit 19 drives the suction surface advance / retreat drive unit 915 to move the rotary stage 911 along the guide groove 914 toward the imaging camera 93 as indicated by an arrow A1 in FIG. Thus, a part of the outer peripheral edge of the wafer 20 held by suction on the rotary stage 911 is positioned above the auxiliary suction means 92, that is, below the imaging camera 93, and a part of the outer peripheral edge of the wafer 20 is taken by the imaging camera. It is positioned in 93 imaging range.

  Following the above mounting process, the grinding apparatus 1 repeatedly performs the imaging data acquisition process, the actual measurement data acquisition process, and the rotation determination process, and the imaging camera 93 performs the rotation by rotating the rotary stage 911 at every predetermined angle. The imaging range is imaged, and imaging data and actual measurement data are acquired.

  Specifically, as shown in FIG. 6, the control unit 19 first captures an imaging range by the imaging camera 93 in a state where the rotation of the rotary stage 911 is stopped and acquires imaging data as an imaging data acquisition process. (Step S3). The acquired imaging data is output to the acquisition data storage unit 931 and stored in the order of imaging.

  Subsequently, as the actual measurement data acquisition step, the control unit 19 drives the suction surface rotation driving unit 913 to rotate the rotation stage 911 by a predetermined angle, and in parallel with the control to rotate the rotation stage 911 by a predetermined angle in this way. The imaging range is continuously captured as a moving image by the imaging camera 93 to obtain actual measurement data (step S5). The acquired imaging data is output to the acquisition data storage unit 931 and stored in the order of imaging.

  And the control means 19 determines whether the rotation of the rotation stage 911 is complete | finished as a rotation determination process. In the present embodiment, the control means 19 determines whether or not the rotary stage 911 has been rotated once (whether or not the wafer 20 has been rotated once), and when the rotary stage 911 has been rotated once, the rotation of the rotary stage 911 is rotated. Is determined to end (step S7). And the control means 19 repeats the imaging data acquisition process of step S3-step S7, an actual measurement data acquisition process, and a rotation determination process based on the determination result of step S7 as a repetition control process. Specifically, the control means 19 returns to step S3 until it is determined that the rotation stage 911 is rotated once in the rotation determination step (step S9: No), and the imaging data acquisition step, the actual measurement data acquisition step, and Each step of the rotation determination step is repeatedly performed. When the rotation angle of the rotary stage 911 is 360 degrees and the rotary stage 911 is rotated once (step S9: Yes), the process proceeds to the circle calculating step of step S11.

  FIG. 9 is an explanatory diagram for explaining the imaging data acquisition process, the actual measurement data acquisition process, and the rotation determination process, and is positioned in the mounting process with respect to the imaging range Ec of the imaging camera 93 indicated by a one-dot chain line in FIG. A wafer 20 is shown. Here, as described above, the imaging camera 93 is, for example, a CCD line sensor, and the detection direction (that is, the imaging range Ec) is an arc indicated by a broken line in FIG. 9 of the wafer 20 placed on the rotary stage 911. For example, the rotary stage 911 is arranged along the forward / backward movement direction (the formation direction of the guide groove 914) so as to be substantially orthogonal to the tangential direction of the circle including the portion 22. The imaging camera 93 detects and outputs the position of the outer peripheral edge of the wafer 20 positioned in the imaging range Ec (the coordinates of the CCD line sensor). Therefore, in the imaging data acquisition process, the actual measurement data acquisition process, and the rotation determination process, the position (when the outer peripheral end is positioned in the imaging range Ec by imaging the imaging range Ec while intermittently rotating the rotary stage 911 ( Coordinates) are detected over the entire circumference of the wafer 20 and acquired as imaging data and actual measurement data.

  In the present embodiment, as shown in FIG. 9, the rotary stage 911 rotates intermittently around the rotation shaft 912 as the axis center while stopping at the rotation angle of 24 degrees and stopping at the rotation angle of 24 degrees. . Then, with the rotation angle (0 degree) of the initial position of the wafer 20 as a reference, the position of the outer peripheral edge at each rotation angle is acquired as imaging data when the rotation stage 911 is stopped every 24 degrees. In parallel with this, when the rotary stage 911 rotates between the respective rotation angles every 24 degrees, the position change of the outer peripheral edge passing through the imaging range Ec with rotation is continuously acquired as measured data.

  In addition, when the outer peripheral end of the wafer 20 is imaged by the imaging camera 93 while the rotary stage 911 is rotated without being stopped, and the position of the outer peripheral end at every 24 degrees is acquired, the grinding apparatus 1 is as follows. Operate. That is, when an encoder (not shown) of the suction surface rotation driving unit 913 detects a rotation angle of every 24 degrees, a detection signal is notified to the control means 19. On the other hand, the control means 19 acquires the position (coordinates) captured by the imaging camera 93 when the detection signal is input from the encoder as the position of the outer peripheral edge at the corresponding rotation angle. Here, due to the processing load of the control means 19 at the time of notification of the detection signal, there may be a delay from when the detection signal is output from the encoder until the control means 19 receives it. This delay may cause a deviation between the position of the outer peripheral edge at each rotation angle of every 24 degrees and the position of the outer peripheral edge taken in from the imaging camera 93. This delay is caused by the encoder notifying the detection signal. Since it is caused by the processing load of the control means 19 at that time, it is difficult to correct it in advance. Therefore, in this embodiment, the rotary stage 911 is not rotated continuously once, but the rotary stage 911 is intermittently rotated while being stopped at each rotation angle every 24 degrees. The position of the outer peripheral end can be appropriately acquired at the rotation angle.

  Following the imaging data acquisition process, the actual measurement data acquisition process, and the acquisition end determination process, the grinding apparatus 1 performs a circle calculation process to calculate the center Wo of the wafer 20 as shown in FIG. 6 (step S11). . 10-12 is explanatory drawing explaining a circle calculation process, and has shown the top view of the wafer 20. FIG. 10 to 12, a circle including the arc portion 22 of the wafer 20 is indicated by a broken line.

  In the circle calculation step, the control unit 19 reads out and uses the imaging data acquired in the imaging data acquisition step with the rotary stage 911 stopped from the acquisition data storage unit 931. In the present embodiment, as shown in FIG. 10, the positions of the outer peripheral ends of 15 points P1 to P15, which are imaging data at each rotation angle every 24 degrees, are acquired as imaging data, and these 15 points P1 to P15. The center Wo of the wafer 20 is calculated using the position of the outer peripheral edge. Specifically, first, as a process corresponding to the temporary center calculation step, the control unit 19 sets three points for each 120 degrees of the 15 points P1 to P15 as one set, and the center of a circle determined by the three points of each set ( A process of calculating each (temporary center) is performed. For example, when attention is paid to a set of three points P5, P10, and P15 at respective rotation angles of 96 degrees, 216 degrees, and 336 degrees, a dot-dash line in FIG. 11 determined by these three points P5, P10, and P15 is obtained by the processing here. The temporary center O1 of the circle indicated by is calculated. This process is performed in the same manner for the other groups, and the temporary centers O1 to O5 of the five groups are calculated as shown in FIG.

  After that, the control means 19 performs processing corresponding to the arc position selection step on the arc portion 22 from the positions of the outer peripheral ends of the five sets of 15 points as the imaging data based on the calculated five sets of temporary centers. Select a position. Then, the center Wo of the wafer 20 is calculated based on the position on the arc portion 22 selected here. First, out of the five sets of calculated temporary centers, those whose positions are greatly deviated are considered to have been calculated including points on the orientation flat 23, and are therefore excluded. For example, the three points P5, P10, and P15 in the set shown in FIG. 11 include the point P15 on the orientation flat 23. The provisional center of the circle of the group including the point on the orientation flat 23 is greatly deviated from the provisional center of the circle of the group not including the orientation flat 23. Therefore, in the present embodiment, for example, the calculated five sets of temporary centers are compared, and two sets of temporary centers are excluded in order from the temporary center farthest from the other temporary centers. Specifically, as shown in FIG. 12, two sets of temporary centers O1 and O5 greatly deviating from three sets of temporary centers O2, O3, and O4 out of the calculated five sets of temporary centers O1 to O5. exclude. Accordingly, the positions of the three sets of nine outer peripheral ends used for calculating the remaining temporary centers O2, O3, and O4 are selected as positions on the arc portion 22.

  Here, two sets of provisional centers are excluded, but this number can be set as appropriate. That is, a set including a position on the orientation flat 23 based on the size of the irregularly shaped portion such as the orientation flat in the wafer to be ground and the angular interval (here, every 24 degrees) between the stop rotation angles for acquiring the imaging data. Since the number can be assumed, at least that number of pairs may be excluded. In addition, a maximum value of a deviation amount between the rotation shaft 912 of the rotation stage 911 and the center Wo of the wafer 20 placed on the rotation stage 911 in the placement process is set in advance, and this deviation amount is set. In consideration of the maximum value, the number of sets including positions on the orientation flat 23 may be assumed.

  Then, based on the position on the selected arc portion 22, specifically, the remaining three sets of temporary centers O2, O3, and O4 are used, and the center of gravity is calculated as the center Wo of the wafer 20. Actually, the temporary centers O2, O3 and O4 of the three sets of circles not including the orientation flat 23 are displaced due to the accuracy of the image processing, the rotational accuracy of the rotary stage 911, and the like. , O3, and O4 are set to the center Wo of the wafer 20 to reduce the center error.

  Following the above circle calculation step, the grinding apparatus 1 performs a reference data creation step as shown in FIG. 6 and creates reference data as a reference when detecting the position of the orientation flat 23 using the imaging data. (Step S13). In the reference data creation step, the control means 19 uses the positions of the outer peripheral edges selected as the positions on the arc portion 22 in the circle calculation step (three sets of nine points used to calculate the temporary centers O2, O3 and O4 in FIG. 12). The reference data is created by using the position of the outer peripheral edge of.

  First, a sine function is calculated for each of the three groups based on the positions of the three outer peripheral edges, and the position on the circumference of the circle determined by the three points for each group is positioned in the imaging range of the imaging camera 93. A sine curve representing the change in position within the imaging range at each rotation angle of the rotary stage 911 is created. The sine curves created for each of the three sets are averaged and used as reference data. FIG. 13 is a graph of an example of reference data in which the horizontal axis represents the rotation angle of the rotary stage 911 and the vertical axis represents the position within the imaging range of the imaging camera 93. As described above, the reference data is obtained by averaging sine curves of sin functions determined by three points of each of the three sets selected as a set not including the orientation flat 23 in the circle calculation process. Therefore, this reference data is a positional change in the imaging range when the position of the outer peripheral edge when the wafer 20 is formed in a circular shape not including the orientation flat 23 is positioned in the imaging range of the imaging camera 93, that is, This corresponds to the position change in the imaging range when the position of the entire circumference of the circle including the arc portion 22 is positioned in the imaging range of the imaging camera 93 for each rotation angle of the rotary stage 911.

  In this case, sine curves are created and averaged for each of the three groups to create reference data. On the other hand, a circle centered on the center of gravity of the temporary centers O2, O3, and O4 (see FIG. 12) obtained as the center Wo of the wafer 20 is identified as a circle including the arc portion 22 based on the three sets of circles. You may make it do. Then, a sine curve representing a change in position within the imaging range when the position on the circumference of the specified circle is positioned in the imaging range of the imaging camera 93 for each rotation angle of the rotary stage 911 is created as reference data. Also good.

  Subsequent to the above reference data creation process, the grinding apparatus 1 performs a deformed portion detection process as shown in FIG. 6 to detect the position of the orientation flat 23 of the wafer 20 on the rotary stage 911 (step S15). . In the irregularly shaped portion detection step, the control means 19 obtains the imaging data acquired while the rotary stage 911 is stopped in the imaging data acquisition step and the actual measurement data acquired while rotating the rotary stage 911 in the actual measurement data acquisition step. The data is read from the storage unit 931 and used. Then, the control means 19 detects the position of the orientation flat 23 by comparing the reference data created in the reference data creation step with the measured data that is the change in the position of the outer peripheral edge between the rotation angles every 24 degrees.

  FIG. 14 is an explanatory diagram for explaining the irregular-shaped portion detection step, where the horizontal axis is the rotation angle of the rotary stage 911 and the vertical axis is the position within the imaging range of the imaging camera 93 shown on the left side in FIG. The reference data graph G31 created based on the imaging data actually obtained by applying this embodiment is shown by a solid line, and the graph G33 showing the imaging data and measured data for each rotation angle is shown by a one-dot chain line. ing. That is, the graph G33 is a graph of imaging data that is the position of the outer peripheral edge at each rotation angle every 24 degrees and actual measurement data that is the position change of the outer peripheral edge between the rotation angles every 24 degrees. . Furthermore, in FIG. 14, the horizontal axis is common (the rotation angle of the rotary stage 911), and the vertical axis is the difference value shown on the right side in FIG. A graph G35 representing the values is indicated by a two-dot chain line.

  As described above, the reference data represents, for each rotation angle of the rotary stage 911, the position change in the imaging range when the position of the entire circumference of the circle including the arc portion 22 is positioned in the imaging range of the imaging camera 93. Is equivalent to On the other hand, the actual measurement data does not necessarily match the reference data because the data acquisition may be delayed during communication (detection signal transmission / reception) between the encoder and the control unit 19 as described above. However, since the value obtained by imaging the orientation flat 23 in the measured data has a large difference from the reference data, by comparing the measured data with the reference data, the rotation angle corresponding to the portion where these differences are large. The range can be specified as the position of the orientation flat 23.

  Specifically, the control means 19 calculates a difference value between the reference data and the actual measurement data for each rotation angle, as indicated by a two-dot chain line in FIG. 14 as a graph G35. Then, the rotation angle range in which the calculated difference value exceeds a predetermined threshold Th set in advance with respect to the scale “0” on the vertical axis shown on the left side of FIG. 14 is set as the position of the orientation flat 23. To detect. In FIG. 14, the rotation angle range L <b> 3 is detected as the position of the orientation flat 23.

  Note that, based on the rotation angle range L3 obtained in this way, the rotation stage 911 is rotated again, and the position of the outer peripheral end in the rotation angle range L3 is positioned in the imaging range of the imaging camera 93 to capture an image. 22 detailed end positions (detailed orientation flat 23 positions) may be detected by imaging with the imaging camera 93.

  Subsequent to the irregular shape detection process described above, the grinding apparatus 1 performs a wafer holding process to suck and hold the surface of the wafer 20 on the holding surface 6s of the holding means 6a (step S17), as shown in FIG. Thereafter, a grinding process is performed to grind the back surface 21 of the wafer 20 on the holding surface 6s (step S19).

  In the wafer holding process, first, as a positioning process, the centering of the wafer 20 is performed by the positioning means 9. FIG. 15 is a side view of the alignment means 9 schematically showing the center alignment of the wafer 20. In this center alignment, the control means 19 firstly forms a straight line connecting the center Wo of the wafer 20 calculated in the circle calculating step and the rotation shaft 912 of the rotary stage 911 and the forward / backward movement direction of the rotary stage 911 (formation of the guide groove 914). The suction surface rotation driving unit 913 is driven to rotate the rotation stage 911 so that the direction is parallel to the direction. As a result, the posture of the wafer 20 is corrected so that the deviation direction of the center Wo of the wafer 20 with respect to the rotation shaft 912 coincides with the forward / backward movement direction of the rotary stage 911.

  Subsequently, the control unit 19 drives the auxiliary suction stage 921 to cause a part of the wafer 20 to be sucked and held by the second suction surface 921a, and to release the suction of the wafer 20 by the first suction surface 911a. As a result, the rotary stage 911 becomes movable relative to the wafer 20. Then, the control unit 19 drives the suction surface advance / retreat drive unit 915 to move the rotation stage 911 into the guide groove 914 by the amount of deviation of the center Wo of the wafer 20 with respect to the rotation shaft 912 as indicated by an arrow A4 in FIG. The rotation axis 912 is made to coincide with the center Wo of the wafer 20 by moving along the axis. Thereby, the center alignment of the wafer 20 is performed. After completing the center alignment as described above, the control unit 19 drives the rotary stage 911 to suck and hold the wafer 20 by the first suction surface 911a, and the wafer 20 by the second suction surface 921a. Release adsorption.

  Subsequently, the alignment unit 9 aligns the wafer 20 in the direction. In this direction alignment, the control means 19 drives the suction surface rotation drive unit 913 to rotate the rotation stage 911 by an amount of deviation between the position of the orientation flat 23 detected in the irregular shape portion detection step and a predetermined position set in advance. Rotate. Thereby, the direction of the wafer 20 is corrected to a preset loading direction, and the direction alignment of the wafer 20 is performed.

  Here, the holding means 6a to 6c on the turntable 5 are arranged such that the irregularly shaped portion holding position 611 on the suction holding portion 61 where the orientation flat 23 is placed at the loading / unloading position before the wafer 20 is loaded is located at a predetermined position. Further, it is appropriately rotated by a rotation drive mechanism (not shown). The loading direction of the wafer 20 is such that the position of the orientation flat 23 is the suction holding unit 61 when the loading unit 10 loads the wafer 20 after the direction alignment to the holding surface 6s of the holding unit 6a at the loading / unloading position. The orientation is set in advance so as to match the upper irregular shape portion holding position 611.

  Then, the control means 19 releases the suction of the wafer 20 by the first suction surface 911a, and the suction pad 103 of the carry-in means 10 places the back surface 21 of the wafer 20 on the rotary stage 911 that is center-aligned and direction-aligned. By adsorbing and holding from above. At this time, the suction pad 103 sucks and holds the center Wo of the wafer 20 centered on the rotation shaft 912. Then, the wafer 20 is loaded onto the holding surface 6s of the holding means 6a located at the loading / unloading position, and the surface side is sucked and held. As a result, the wafer 20 is loaded onto the holding surface 6 s in such a direction that the position of the orientation flat 23 matches the irregularly shaped portion holding position 611 on the suction holding portion 61.

  In the subsequent grinding process, under the control of the control means 19, first, the holding means 6 a at the loading / unloading position where the surface of the wafer 20 is sucked and held on the holding surface 6 s as described above in the wafer holding process is provided on the turntable 5. It moves to the grinding position by the grinding means 3 with the rotation. Then, the back surface 21 of the wafer 20 is subjected to grinding by the grinding wheel 3b. Specifically, the grinding wheel 3b is rotationally driven, and the back surface 21 of the wafer 20 is ground by being lowered and fed to the wafer 20 by the ascending / descending feed means 15. At the same time, the wafer 20 that has finished grinding at the grinding position by the grinding means 3 on the holding surface 6s of the holding means 6b moves to the grinding position by the grinding means 4, and the back surface 21 of the wafer 20 is moved to the grinding wheel 4b. Used for grinding. During this time, the carry-in means 10 carries the next wafer 20 onto the holding surface 6s of the holding means 6c that has moved to the carry-in / out position, and holds the surface side by suction.

  Subsequently, when the grinding process by the grinding means 3 is completed, the holding means 6a moves to the grinding position by the grinding means 4 along with the rotation of the turntable 5, and the back surface 21 of the wafer 20 is subjected to the grinding process by the grinding wheel 4b. At the same time, the next wafer 20 loaded onto the holding surface 6s of the holding means 6c and sucked and held on the front side moves to a grinding position by the grinding means 3, and the back surface 21 of the wafer 20 is ground by the grinding wheel 3b. To serve. During this time, the wafer 20 that has been ground by the grinding means 4 on the holding surface 6s of the holding means 6b moves to the loading / unloading position.

  Here, the wafer 20 at the carry-in / carry-out position after the grinding by the grinding means 3 and the grinding means 4 is carried out to the cleaning means 12 with the back surface 21 side being sucked and held by the suction pad 113 of the carry-out means 11. After the back surface 21 is cleaned by the cleaning unit 12, the wafer 20 transferred to the cleaning unit 12 is gripped by the U-shaped hand 13 a of the transfer-in / out unit 13, transferred to the cassette 8, and accommodated in the cassette 8. The After unloading the wafer 20 after the above-described grinding, the loading means 10 loads the next wafer 20 onto the holding surface 6s of the holding means 6b and sucks and holds the surface side.

  Thereafter, the holding means 6 a that has finished grinding by the grinding means 4 moves to the carry-in / carry-out position as the turntable 5 rotates. At the same time, the wafer 20 that has finished grinding at the grinding position by the grinding means 3 on the holding surface 6s of the holding means 6c moves to the grinding position by the grinding means 4, and the back surface 21 of the wafer 20 is moved to the grinding wheel 4b. Used for grinding. In addition, the wafer 20 that has been carried into the holding means 6b and whose front side is sucked and held moves to a grinding position by the grinding means 3, and the back surface 21 of the wafer 20 is subjected to grinding by the grinding wheel 3b. The above operation is repeated for each wafer 20 accommodated in the cassette 7.

  As described above, according to the present embodiment, the imaging range is imaged by the imaging camera 93 while intermittently rotating the rotary stage 911 on which the wafer 20 is placed at every predetermined angle, and imaging data and actual measurement data are captured. Can be obtained. Specifically, the position of the outer peripheral edge positioned in the imaging range of the imaging camera 93 when the rotary stage 911 is stopped at each rotation angle for each predetermined angle is acquired as imaging data, and between each rotation angle for each predetermined angle. When the rotary stage 911 is rotated, the position change of the outer peripheral end passing through the imaging range of the imaging camera 93 along with this rotation can be acquired as measured data. After that, the center of the circle including the arc portion 22 is calculated by selecting the position on the arc portion 22 from the positions of the outer peripheral ends at the rotation angle for each predetermined angle that is the imaging data. The reference data can be created by calculating the sine function based on the position of the outer peripheral edge selected as the position on the arc portion 22 from the inside. This reference data is a sine curve representing the position change in the imaging range when the position of the entire circumference of the circle including the arc portion 22 is positioned in the imaging range of the imaging camera 93 for each rotation angle of the rotary stage 911. Yes, the position of the irregularly shaped portion can be detected by comparing the change in the position of the outer peripheral edge of the wafer 20 acquired as the actual measurement data with the created reference data.

  According to this, unlike the conventional method, it is not necessary to align the center of the wafer 20 with the rotation axis of the rotary stage prior to detecting the position of the irregularly shaped portion such as the orientation flat 23. Therefore, since the imaging of the outer peripheral edge of the wafer 20 may be performed once while the rotary stage 911 is intermittently rotated, the time required to detect the position of the orientation flat 23 can be shortened. According to this, there is an effect that the position of the orientation flat 23 formed on the outer peripheral edge of the wafer 20 can be quickly detected.

  Note that the present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

(Modification 1)
For example, in the above-described embodiment, the alignment unit 9 performs the center alignment of the wafer 20 to perform the direction alignment. On the other hand, it is good also as a structure which operate | moves as follows. That is, first, when the control unit 19 moves the straight line connecting the center Wo of the wafer 20 calculated in the circle calculation step and the rotation shaft 912 of the rotary stage 911 and the suction pad 103 of the carry-in unit 10 to the upper side of the alignment unit 9. The suction surface rotation driving unit 913 is driven to rotate the rotation stage 911 so that the expansion / contraction movement direction of the second arm 102b (the major axis direction of the first arm 102a) is parallel. Thus, the posture of the wafer 20 is corrected so that the deviation direction of the center Wo of the wafer 20 with respect to the rotation shaft 912 coincides with the expansion / contraction movement direction of the suction pad 103.

  On the other hand, the control means 19 appropriately rotates the holding means 6a located at the carry-in / out position by a rotation drive mechanism (not shown) to change the irregularly shaped part holding position 611 on the suction holding part 61 on which the orientation flat 23 is placed. It moves according to the position of the orientation flat 23 detected in the shape part detection step. That is, when the wafer 20 on the rotation stage 911 is loaded onto the holding surface 6s of the holding means 6a at the loading / unloading position, the irregularly shaped portion holding position 611 on the suction holding portion 61 is aligned with the position of the orientation flat 23. Move.

  In parallel with this, the control means 19 releases the suction of the wafer 20 by the first suction surface 911 a and rotates the transfer arm portion 102 of the loading means 10 to rotate the suction pad 103 on the positioning means 9. Move. Thereafter, the control means 19 expands and contracts the second arm 102b by the amount of displacement of the center Wo of the wafer 20 with respect to the rotation shaft 912 to move the suction pad 103 along the expansion / contraction movement direction, and the wafer 20 on the rotation stage 911 moves. The back surface 21 is sucked and held from above by the suction pad 103. As a result, the center Wo of the wafer 20 is sucked and held by the suction pad 103. Then, the wafer 20 is loaded onto the holding surface 6s of the holding means 6a located at the loading / unloading position, and the surface side is sucked and held.

  Also in the configuration of the modified example 1, as in the above-described embodiment, the wafer 20 is loaded onto the holding surface 6s in a direction in which the orientation flat 23 is aligned with the irregularly shaped portion holding position 611 on the suction holding portion 61. It can be held by suction by the suction holding unit 61. Further, according to the first modification, it is not necessary to perform the center alignment of the wafer 20 shown in FIG. 15 in the alignment unit 9, and it is necessary to carry the wafer 20 onto the holding surface 6s of the holding unit 6a. You can save time.

(Modification 2)
In the above-described embodiment, the case where the wafer 20 is loaded onto the holding surface whose outer shape substantially coincides with the wafer 20 by detecting the position of the orientation flat 23 has been exemplified. In addition to this, there are other cases where the position of the part needs to be detected, for example. That is, when the grinding machine 1 is used to grind the wafer 20 as thin as, for example, 50 μm or less, the wafer 20 is likely to be damaged and is difficult to handle. In order to solve such a problem, the back surface 21 is ground as a surface to be ground so that the outer edge portion remains as a reinforcing portion, and a concave portion formed by grinding on the back surface 21 side of the wafer 20 and a ring-shaped convex portion surrounding the concave portion May form. Specifically, as shown in FIG. 1, the back surface 21 corresponding to the front side region (device region) having the device 24 effective for commercialization is ground, and the outer region (surplus region) surrounding this device region ) May be formed on the back surface 21 corresponding to (). However, when the orientation flat 23 exists at the outer peripheral edge as in the wafer 20, if an attempt is made to grind leaving the outer edge with reference to the center Wo of the wafer 20 and form a ring-shaped convex portion as a reinforcing portion, the orientation flat At 23, the reinforcing part is interrupted or the reinforcing part becomes thin. In order to prevent such a situation and to calculate the processing center in order to form the reinforcing portion evenly, it is necessary to detect the position of the orientation flat 23.

  Here, the grinding apparatus of the modification 2 can be realized with the same configuration as the grinding apparatus 1 of the above-described embodiment, and the wafer holding process and the grinding process are different from the above-described embodiment. Hereinafter, the same reference numerals are given to the same configurations as those in the above-described embodiment, and the wafer holding process and the grinding process in Modification 2 will be described. FIG. 16 is an explanatory diagram for explaining direction alignment in the second modification. FIG. 17 is an explanatory view for explaining the wafer holding process after the direction alignment in the second modification. FIG. 18 is an explanatory diagram for explaining a grinding process in the second modification.

  First, the wafer holding process in Modification 2 will be described. In the wafer holding process of the second modification, the control unit 19 first performs center alignment of the wafer 20 in the alignment unit 9 as described with reference to FIG.

  Subsequently, the alignment unit 9 aligns the wafer 20 in the direction. In the direction alignment in the second modification, the control unit 19 drives the suction surface rotation driving unit 913 to rotate the rotation stage 911, thereby rotating the orientation flat with respect to the forward / backward movement direction of the rotation stage 911 shown in FIG. 23 is a right angle. By aligning the direction in this way, the intersection N of the orientation flat 23 and the center straight line M that passes through the center Wo of the wafer 20 and is orthogonal to the orientation flat 23 is indicated by an alternate long and short dash line in FIG. It is positioned in the imaging range Ec of the camera 93.

  In this state, the control means 19 images the imaging range Ec with the imaging camera 93 and detects the position (coordinates) of the intersection N between the center straight line M and the orientation flat 23. Further, the control means 19 drives the suction surface rotation drive unit 913 to rotate the rotation stage 911 by 180 degrees. Subsequently, the control unit 19 images the imaging range Ec with the imaging camera 93 and detects the position (coordinates) of the intersection point P between the central straight line M and the arc portion 22. And the control means 19 calculates the position (coordinate) of the center point between the intersection N and the intersection P as the process center Wpo. At this time, the control means 19 calculates a deviation amount Δ of the processing center Wpo with respect to the center Wo of the wafer 20. Thereafter, the control unit 19 drives the suction surface rotation driving unit 913 to further rotate the rotary stage 911 by 180 degrees, thereby returning the wafer 20 to the original position shown in FIG.

  However, the shape of the wafer 20 (the radius of the circle including the arc portion 22, the distance between the center of the circle and the orientation flat 23, etc.) may be known. In such a case, the processing center Wpo and the shift amount Δ may be calculated based on the known information, and the positions of the intersections N and P are imaged by the imaging camera 93 and detected as described above. It is good also as a structure which does not perform the process to perform. Alternatively, as described with reference to FIG. 12 in the above-described embodiment, three sets of circles each centered on the temporary centers O2, O3, and O4 used for obtaining the center Wo of the wafer 20 in the circle calculation step. Based on the above, it is possible to specify a circle centered on the center of gravity (center Wo of the wafer 20) of each temporary center O2, O3, O4 as a circle including the arc portion 22. Even in such a case, the positions of the intersections N and P can be calculated from the specified circle and the detected position of the orientation flat 23. As described above, the process of detecting the positions of the intersections N and P by imaging with the imaging camera 93 can be omitted as appropriate.

  Subsequently, the control means 19 carries the straight line (the orthogonal direction of the orientation flat 23) connecting the center Wo of the wafer 20 and the processing center Wpo, which coincides with the rotation axis 912 of the rotary stage 911 by the center alignment, and the carry-in means 10. The suction surface rotation drive unit 913 is driven to rotate the rotation stage 911 so that the suction arm 103 moves in parallel with the expansion / contraction movement direction of the second arm 102b when the suction pad 103 is moved above the alignment means 9. Thereby, the wafer 20 is directionally aligned so that the deviation direction of the processing center Wpo with respect to the center Wo of the wafer 20 matches the expansion / contraction movement direction of the suction pad 103.

  Thereafter, the control means 19 releases the suction of the wafer 20 by the first suction surface 911a. Further, under the control of the control unit 19, the carry-in unit 10 rotates the transport arm unit 102 to move the suction pad 103 onto the alignment unit 9. Then, the back surface 21 of the wafer 20 on the rotation stage 911 that has been center-aligned and direction-aligned is sucked and held from above by the suction pad 103 of the loading means 10. At this time, the suction pad 103 sucks and holds the center Wo of the wafer 20 centered on the rotation shaft 912. Then, as shown by a broken line in FIG. 17, the carry-in means 10 carries the wafer 20 as it is onto the holding surface 6s of the holding means 6a in a state where the center Wo of the wafer 20 coincides with the rotation center 6o of the holding means 6a.

  Then, under the control of the control means 19, the carry-in means 10 expands and contracts the second arm 102 b by the amount Δ of the processing center Wpo with respect to the center Wo of the wafer 20 to move the suction pad 103 along the expansion / contraction movement direction. As shown by the solid line in FIG. 17, the machining center Wpo is made to coincide with the rotation center 6o. In this state, the wafer 20 is placed on the holding surface 6s of the holding means 6a and is sucked and held by a suction holding unit (not shown). Here, the holding means 6a to 6c according to the modified example 2 replaces the suction holding unit 61 having a configuration in which the outer shape of the upper surface shown in FIG. The suction holding unit is configured such that the entire region or a part thereof forms the entire region or a part of the holding surface 6s.

  In addition, after the direction alignment of the orientation flat 23 is performed, the suction surface advance / retreat driving unit 115 may be driven in the same manner as the center alignment so that the processing center Wpo coincides with the rotation shaft 112. After that, the loading means 10 may suck and hold the processing center Wpo by the suction pad 103, and the wafer 20 may be transferred onto the holding surface 6s of the holding means 6a so that the processing center Wpo coincides with the rotation center 6o. . Alternatively, when the wafer 20 is sucked by the suction pad 103 on the alignment means 9, the second arm 102 b is expanded and contracted by an amount Δ of the processing center Wpo relative to the center Wo of the wafer 20, and the suction pad 103 is moved along the direction of expansion and contraction. The processing center Wpo may be sucked and held by the suction pad 103. And it is good also as a structure which carries in the wafer 20 on the holding surface 6s of the holding means 6a so that this process center Wpo may correspond with the rotation center 6o.

  As described above, when the wafer 20 is loaded and sucked and held on the holding surface 6s of the holding means 6a at the loading / unloading position, the grinding process is started. In the grinding process of the modified example 2, by rotating the turntable 5 120 degrees, the holding means 6a is positioned at the position of the holding means 6b, the wafer 20 is rotated around the processing center Wpo, and the grinding wheel of the grinding means 3 is used. 3b is rotated to process the center from the back surface 21 side of the wafer 20 into a concave shape. That is, by moving the movable block 17 forward and backward, as shown in FIG. 18, the outer peripheral side end of the grinding wheel 3b is positioned with respect to the wafer 20 so as to leave the back surface 21 side of the surplus region by a predetermined size, and at a high speed. The rotating grinding wheel 3b is lowered with respect to the wafer 20 by the lifting / lowering feeding means 15 and is ground and fed, whereby a predetermined thickness is ground from the back surface 21 side. Thus, grinding is performed by leaving the outer edge portion of the wafer 20 from the back surface 21 side of the wafer 20, and forming a recess 211 by grinding and a ring-shaped reinforcing portion 213 surrounding the recess 211 on the back surface 21 side of the wafer 20. Is executed. The same applies to the grinding by the grinding wheel 4b of the grinding means 4 at the position of the holding means 6c. In the modified example 2, the grinding wheel 3b (grinding wheel 3c) and the grinding wheel 4b (grinding wheel 4c) are such that the diameter of the outermost circumference of the rotation locus is larger than the radius of the device region and smaller than the diameter of the device region. Is formed.

  FIG. 19 is a perspective view showing the back surface 21 side of the wafer 20 ground by the grinding apparatus of the second modification. As shown in FIG. 19, according to Modification 2, only the region corresponding to the device region of the back surface 21 of the wafer 20 is ground, the recess 211 is formed on the back surface 21, and the surplus region is supported. A ring-shaped reinforcing portion 213 having a thickness equivalent to that before grinding remains on the outer peripheral portion. This reinforcement part 213 becomes a holding part by the carrying-out means 11 etc. after completion | finish of grinding.

  According to the second modification, it is possible to detect the position of the orientation flat 23 and obtain the processing center Wpo of the wafer 20 so that the ring-shaped reinforcing portion 213 is formed uniformly, and to grind the back surface 21 side. It becomes.

(Other variations)
In the above-described embodiment, the case where it is determined whether or not the rotation stage 911 is rotated once in the rotation determination step is described. However, it is not always necessary to rotate the rotation stage 911 once. For example, the minimum rotation amount of the rotary stage 911 required to detect the position of the irregularly shaped portion such as the orientation flat 23 may be set, and the rotary stage 911 may be rotated by this rotation amount. Here, the minimum amount of rotation of the rotary stage 911 necessary for detecting the position of the irregularly shaped portion is the size of the irregularly shaped portion, the maximum value of the above-described deviation amount, It can be set in advance based on the rough position of the irregularly shaped portion.

  In the above-described embodiment, the orientation flat 23 has been described as the irregular shape portion indicating the crystal orientation, but the shape of the irregular shape portion is not particularly limited. FIG. 20 is a perspective view showing another example of the irregularly shaped portion, and shows the wafer 20a in which the notch 23a is formed. For example, as shown in FIG. 20, the present invention can be similarly applied to a wafer 20a having an arcuate portion 22a and a notch 23a that occupy the majority.

  As described above, the detection method, the wafer carry-in method, and the detection apparatus of the present invention are suitable for quickly detecting the position of the irregularly shaped portion formed on the outer peripheral edge of the wafer.

DESCRIPTION OF SYMBOLS 1 Grinding device 3, 4 Grinding means 5 Turntable 6a, 6b, 6c Holding means 9 Positioning means 91 Rotation adsorption means 911 Rotation stage 911a 1st adsorption surface 912 Rotating shaft 913 Adsorption surface rotation drive part 915 Adsorption surface advance / retreat drive part 92 Auxiliary suction means 921 Auxiliary suction stage 921a Second suction surface 93 Imaging camera 931 Acquisition data storage means 10 Carry-in means 11 Carry-out means 12 Cleaning means 13 Carry-in / out means 19 Control means 20 Wafer 22 Arc portion 23 Orientation flat

Claims (6)

A placing step of placing a wafer, the outer peripheral end of which is composed of an arc part and an irregularly shaped part, on a rotary stage, and positioning a part of the outer peripheral end of the wafer within the imaging range of the imaging camera;
The imaging range is imaged by the imaging camera in a state where the rotation stage is stopped at a predetermined rotation angle that is predetermined as a stop rotation angle, and the outer peripheral edge of the wafer at the stop rotation angle positioned within the imaging range is detected. An imaging data acquisition step of acquiring a position as imaging data;
The imaging range is continuously imaged by the imaging camera while rotating the rotation stage to the next stop rotation angle, and the wafer passing through the imaging range as the rotation stage rotates between the stop rotation angles. Actual measurement data acquisition process for acquiring the position change of the outer peripheral edge as actual measurement data;
A rotation determination step for determining whether or not to end the rotation of the rotary stage;
A repetitive control step for repeatedly performing the imaging data acquisition step, the actual measurement data acquisition step, and the rotation determination step until it is determined in the rotation determination step that rotation of the rotary stage is to be terminated,
An arc portion position selecting step of selecting a position on the arc portion from the positions of the outer peripheral ends at the stop rotation angle acquired as the imaging data;
Based on the position on the arc portion selected in the arc portion position selection step, the position change in the imaging range when the position of the entire circumference of the circle including the arc portion is positioned in the imaging range A reference data creation step of creating reference data representing the rotation angle of each rotation stage;
An irregular shape detection step of detecting the position of the irregular shape portion by comparing the change in position of the outer peripheral edge of the wafer acquired as the actual measurement data with the reference data;
A detection method comprising:   The detection method according to claim 1, wherein the center of a circle including the arc portion is calculated based on the position on the arc portion selected in the arc portion position selecting step. The arc portion position selection step includes:
A provisional center calculation step of grouping the imaging data into a plurality of groups each including at least three, and calculating a center of a circle determined by a position of an outer peripheral edge of the imaging data for each group as a provisional center;
Each set excluding the set used to calculate the excluded temporary centers by comparing the temporary centers calculated for each of the plurality of sets and excluding a predetermined number in order from the temporary centers that are most significantly different from the other temporary centers. The position of the outer peripheral edge of the imaging data is selected as the position on the arc portion,
The detection method according to claim 1, wherein the predetermined number is preset based on a size of the irregularly shaped portion and an angular interval between the stop rotation angles.   The irregularly shaped portion detecting step calculates a difference value for each rotation angle between the position change of the outer peripheral edge of the wafer acquired as the actual measurement data and the reference data, and the difference value is set to a predetermined threshold value. The detection method according to claim 1, wherein a position of an outer peripheral end positioned in the imaging range in a rotation angle range that exceeds is detected as the position of the irregularly shaped portion. A grinding apparatus comprising: a holding unit having a holding surface for holding a wafer whose outer peripheral end is composed of an arc portion and an irregularly shaped portion; and a grinding unit for grinding the wafer held on the holding surface of the holding unit In the wafer loading method of loading the wafer onto the holding surface of the holding means,
Placing the wafer on a rotating stage, and placing a part of the outer peripheral edge of the wafer within an imaging range of an imaging camera;
The imaging range is imaged by the imaging camera in a state where the rotation stage is stopped at a predetermined rotation angle that is predetermined as a stop rotation angle, and the outer peripheral edge of the wafer at the stop rotation angle positioned within the imaging range is detected. An imaging data acquisition step of acquiring a position as imaging data;
The imaging range is continuously imaged by the imaging camera while rotating the rotation stage to the next stop rotation angle, and the wafer passing through the imaging range as the rotation stage rotates between the stop rotation angles. Actual measurement data acquisition process for acquiring the position change of the outer peripheral edge as actual measurement data;
A rotation determination step for determining whether or not to end the rotation of the rotary stage;
A repetitive control step for repeatedly performing the imaging data acquisition step, the actual measurement data acquisition step, and the rotation determination step until it is determined in the rotation determination step that rotation of the rotary stage is to be terminated,
The position on the arc portion is selected from the positions of the outer peripheral ends at the stop rotation angle acquired as the imaging data, and the center of the circle including the arc portion is determined based on the selected position on the arc portion. A circle calculating step to calculate;
Based on the position on the arc portion selected in the circle calculation step, the position change in the imaging range when the position of the entire circumference of the circle including the arc portion is positioned in the imaging range. A reference data creation step for creating reference data for each rotation angle of the rotary stage;
An irregular shape detection step of detecting the position of the irregular shape portion by comparing the change in position of the outer peripheral edge of the wafer acquired as the actual measurement data with the reference data;
An alignment step of matching the center of the circle including the arc portion with the rotation center of the rotary stage;
Based on the position of the irregular shape portion detected in the irregular shape portion detection step, a wafer holding step of holding the wafer on the holding surface in a predetermined orientation;
A wafer carrying-in method comprising: An imaging camera;
A rotary stage in which an outer peripheral end is rotatably mounted with a circular arc part and an irregularly shaped part, and a part of the outer peripheral end of the wafer is positioned within the imaging range of the imaging camera;
The imaging range is imaged by the imaging camera when the rotation stage is stopped at the stop rotation angle while intermittently rotating while the rotation stage is stopped at a predetermined rotation angle that is predetermined as a stop rotation angle. The position of the outer peripheral edge of the wafer within the imaging range is acquired as imaging data, and the imaging range is continuously imaged by the imaging camera during rotation of the rotary stage, and the rotary stage between the stop rotation angles Data acquisition means for acquiring, as measured data, a change in position of the outer peripheral edge of the wafer that passes through the imaging range with rotation of
An arc portion position selecting means for selecting a position on the arc portion from the positions of the outer peripheral ends at the stop rotation angle acquired as the imaging data;
Based on the position on the arc portion selected by the arc portion position selection means, the position change in the imaging range when the position of the entire circumference of the circle including the arc portion is positioned in the imaging range A reference data creating means for creating reference data representing each rotation angle of the rotary stage;
An irregularly shaped part detecting means for detecting a position of the irregularly shaped part by comparing a change in position of the outer peripheral edge of the wafer acquired as the actual measurement data with the reference data;
A detection apparatus comprising:

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