JP2012069677A - Grinding apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding apparatus which can suppress a positional deviation with respect to a rotating temporary mount table even for a wafer having irregularities on a surface thereof, and can accurately detect a position of the wafer.SOLUTION: The grinding apparatus includes the temporary mount table 35 with a support surface 64 for supporting the wafer W; a photographing part 36 for photographing outer peripheral edge portions of the wafer W supported by the support surface 64; a rotation part 61 which rotates the temporary mount table 35 around a vertical axis orthogonal to the support surface 64, and allows the outer peripheral edge portions of the wafer W to sequentially enter a photographing range of the photographing part 36. The support surface 64 of the temporary mount table 35 is formed by a frictional material 65 that imparts to the wafer W a frictional force larger than a force exerted on the wafer W by the rotation.

Description

  The present invention relates to a grinding apparatus capable of positioning a wafer at a predetermined position with respect to a chuck table when grinding the wafer.

  A semiconductor chip on which a device such as an IC or LSI is formed is indispensable for downsizing various electronic devices. In this semiconductor chip, the surface of a substantially disk-shaped wafer is divided into a plurality of rectangular areas by lattice-shaped division lines (streets), devices are formed in the divided rectangular areas, and then along the division lines. It is manufactured by dividing the rectangular area.

  In such a semiconductor chip manufacturing process, the wafer is ground to a predetermined thickness by a grinding apparatus prior to the division of the wafer. This grinding apparatus holds a wafer before division on a chuck table and grinds the wafer by relative rotation between the chuck table and a grinding wheel. By the way, in the semiconductor wafer, an irregular shape portion such as an orientation flat or a notch showing a crystal orientation is formed on the outer peripheral edge portion, and the orientation is specified by the irregular shape portion. For this reason, in the grinding apparatus, it is necessary to carry the semiconductor wafer in a predetermined direction and position with respect to the chuck table.

  Conventionally, detection means for detecting the position and orientation of a wafer before carrying the wafer into the chuck table has been proposed (see, for example, Patent Document 1). The detection means includes a table that holds the wafer in a vacuum system, and an imaging unit that images the outer peripheral edge of the wafer held on the table. The detection means detects the position (for example, the center position) and orientation of the wafer by sequentially imaging the outer peripheral edge of the wafer with the imaging unit while rotating the table. Then, the wafer is carried into the chuck table so as to be accurately positioned on the chucking surface of the chuck table based on the detection result of the detection means.

JP 2010-147134 A

  By the way, some wafers have bumps and the like formed on the surface so as to be uneven. A protective tape is attached to the surface of this type of wafer, but if the surface has large irregularities, the irregularities cannot be completely absorbed by the protective tape. For this reason, when the wafer is placed on the table of the detection means with the surface facing downward, a gap is formed between the wafer surface (tape surface) and the table, and the suction force from the vacuum table is sufficiently exerted. There was no case. For this reason, in the detection means described in Patent Document 1, there is a possibility that the wafer is displaced in the horizontal direction due to the rotation of the table, and there is a problem that the detection accuracy is lowered.

  The present invention has been made in view of the above points, and provides a grinding apparatus that can suppress a positional deviation with respect to a rotating table and can accurately detect the position of the workpiece even if the workpiece has an uneven surface. Objective.

  The grinding apparatus of the present invention includes a holding means for holding a work, a grinding means for grinding the work held by the holding means, and a detection for detecting at least the position of the work before carrying the work into the holding means. And a detection unit comprising: a table that supports a workpiece; an imaging unit that images the workpiece supported by the table; and a rotation unit that rotates the table about a vertical direction as a rotation axis. And a rotary encoder that detects a rotational position of the rotating unit, and a support surface that supports the workpiece of the table restricts the workpiece from being displaced in the horizontal direction when the table is rotated by the rotating unit. It is formed of a member that generates a frictional force having a magnitude.

  According to this configuration, not only a flat surface workpiece but also a workpiece having an uneven surface, the workpiece is appropriately held by the frictional force generated on the table. For this reason, the workpiece is not displaced in the horizontal direction due to the rotation of the table, and the position of the workpiece can be accurately detected by the detecting means. In addition, unlike a conventional vacuum table, a suction source is not required, so that the manufacturing cost can be reduced with a simple device configuration.

  According to the present invention, the manufacturing cost can be reduced with a simple apparatus configuration, and even a workpiece having an uneven surface can suppress positional displacement with respect to the rotating table and can accurately detect the position of the workpiece. .

1 is an external perspective view of a grinding apparatus according to an embodiment of the present invention. It is an enlarged view of the detection part periphery of the grinding device which concerns on the said embodiment. It is explanatory drawing of the acquisition process of the imaging data by the imaging part which the grinding apparatus which concerns on the said embodiment has, and measurement data. It is explanatory drawing of the calculation process of the wafer center position in the grinding apparatus which concerns on the said embodiment. It is other explanatory drawing of the calculation process of the center position of the wafer in the grinding apparatus which concerns on the said embodiment. It is other explanatory drawing of the calculation process of the center position of the wafer in the grinding apparatus which concerns on the said embodiment. It is a figure which shows an example of the reference data in the grinding apparatus which concerns on the said embodiment. It is explanatory drawing of the calculation process of the formation position of orientation flat in the grinding apparatus which concerns on the said embodiment. It is explanatory drawing of the positioning operation | movement of the position and orientation of a wafer with respect to the chuck table which the grinding apparatus which concerns on the said embodiment has.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. FIG. 1 is an external perspective view of a grinding apparatus 1 according to an embodiment of the present invention. In the following description, an example in which the detection mechanism, which is a feature of the present invention, is applied to a grinding apparatus will be described. However, not only the grinding apparatus but also the processing for positioning the orientation and center position of the wafer on the chuck table (holding means). It is also possible to apply to an apparatus.

  As shown in FIG. 1, the grinding apparatus 1 relatively rotates the chuck table 3 holding the wafer W with the back side facing upward and the grinding wheel 59 of the grinding unit (grinding means) 4 to thereby rotate the wafer W. It is comprised so that the back surface of may be ground. The wafer W is formed in a substantially disk shape, and is divided into a plurality of regions by unscheduled division lines (not shown) arranged on the surface in a grid pattern. Devices such as ICs and LSIs are formed in each region partitioned by the division lines.

  A plurality of protruding electrodes (bumps) (not shown) are formed on the surface of the wafer W as terminals for connecting these devices to a substrate or the like. The plurality of electrodes are arranged on the surface of the wafer W at a predetermined interval, and form irregularities on the surface of the wafer W. A protective tape is attached to the surface of the wafer W, and the device is protected by this protective tape when the back surface of the wafer W is processed. At the outer peripheral edge of the wafer W, an orientation flat 71 showing a crystal orientation is formed by cutting a part of the wafer W flat. The wafer W configured as described above is carried into the grinding apparatus 1 while being accommodated in the cassette 6 on the carry-in side.

In the present embodiment, a wafer W such as a silicon wafer (Si), gallium gallium (GaAs), or silicon carbide (SiC) will be described as an example of the workpiece. However, the present invention is not limited to this configuration. For example, ceramic, glass, sapphire (Al ₂ O ₃ ) -based inorganic material substrates, ductile materials of sheet metal and resin, and various processes requiring flatness (TTV: total thickness variation) from the micron order to the submicron order. The material may be a workpiece. The flatness referred to here indicates the difference between the maximum value and the minimum value among the heights measured in the thickness direction using the surface to be ground of the workpiece as a reference surface.

  The grinding apparatus 1 has a substantially rectangular parallelepiped base 2, and a pair of cassette mounting portions 11 and 12 on which the cassettes 6 and 7 are mounted are provided on the base 2 so as to protrude forward from the front surface 8. It has been. The cassette placement unit 11 functions as a carry-in port, and the carry-in cassette 6 in which the wafer W before processing is accommodated is placed. The cassette mounting portion 12 functions as a carry-out port, and the carry-out cassette 7 in which the processed wafer W is accommodated is placed.

  On the upper surface of the base 2, a loading / unloading arm 13 for loading and unloading the wafers W with respect to the cassettes 6 and 7 is provided facing the cassette mounting portions 11 and 12. On one side of the loading / unloading arm 13, a detection unit (detection unit) 14 that detects the center position of the wafer W before processing and the orientation flat 71 is provided. A cleaning unit 15 for cleaning the processed wafer W is provided on the other side of the loading / unloading arm 13.

  Between the detection unit 14 and the cleaning unit 15, a wafer supply unit 16 that supplies the wafer W before processing to the chuck table 3 and a wafer recovery unit 17 that recovers the processed wafer W from the chuck table 3 are provided. ing. Further, on the upper surface of the base 2, a rectangular opening 21 extending in the front-rear direction is formed adjacent to the wafer supply unit 16 and the wafer recovery unit 17, and the grinding unit 4 is disposed behind the opening 21. A supporting column 22 is erected. In addition, a control unit 23 that performs overall control of the grinding device 1 is provided inside the base 2.

  The opening 21 is covered with a movable plate 24 that can move together with the chuck table 3 and a bellows-shaped waterproof cover 25. Below the waterproof cover 25, a ball screw type moving mechanism (not shown) for moving the chuck table 3 in the front-rear direction is provided. The chuck table 3 is reciprocated between a transfer position where the wafer W is transferred to the wafer supply unit 16 and the wafer recovery unit 17 and a processing position facing the grinding unit 4 by a moving mechanism.

  The carry-in / out arm 13 includes a multi-node link mechanism 31 having a wide driving area and a holding portion 32 provided at the tip of the multi-node link mechanism 31. The loading / unloading arm 13 drives the multi-joint link mechanism 31 to load the wafer W accommodated in the loading-side cassette 6 into the detection unit 14 and also transfers the wafer W from the cleaning unit 15 to the loading-side cassette 7. Accommodate.

  The detection unit 14 includes a temporary placement table (table) 35 on which the wafer W is temporarily placed by the loading / unloading arm 13 and an imaging unit 36 that images the wafer W temporarily placed on the temporary placement table 35. The temporary placement table 35 is formed in a disc shape and is intermittently rotated at a predetermined angular interval while holding the wafer W. A support surface 64 that supports the wafer W by friction is formed on the upper surface of the temporary placement table 35. In this case, the surface of the wafer W that is in contact with the support surface 64 is formed in an uneven shape, but positional displacement due to the rotation of the temporary placement table 35 is prevented by the frictional force of the support surface 64.

  The imaging unit 36 is supported above the temporary placement table 35 via an L-shaped support arm 66 and images a part of the outer peripheral edge of the wafer W on the temporary placement table 35. The imaging unit 36 sequentially images the outer peripheral edge of the wafer W in accordance with intermittent rotation of the temporary placement table 35. The imaging result of the imaging unit 36 is output to the control unit 23, and the center position of the wafer W and the formation position of the orientation flat 71 are obtained. The detailed configuration of the detection unit 14 will be described later.

  The wafer supply unit 16 includes a pivot shaft 41 extending in the vertical direction, a swing arm 42 supported on the upper end of the pivot shaft 41, and a suction holding unit that holds the wafer W by suction. Part 43. The rotation shaft 41 is configured to be movable up and down, back and forth, and rotatable. The position of the suction holding portion 43 in the horizontal plane is adjusted by moving the rotating shaft 41 back and forth and rotating, and the position in the height direction is adjusted by moving the rotating shaft 41 up and down.

  The wafer supply unit 16 is driven and controlled by the control unit 23, and the control unit 23 adjusts the amount of movement of the rotation shaft 41 in the vertical direction, the amount of movement in the front-rear direction, and the rotation amount. Then, the wafer supply unit 16 is controlled by the control unit 23, sucks and holds the wafer W from the temporary placement table 35, lifts it, and supplies it to the chuck table 3. At this time, the center of the wafer W is aligned with the center of the chuck table 3.

  The wafer collection unit 17 has substantially the same configuration as the wafer supply unit 16 except that it does not move back and forth. The wafer collection unit 17 is controlled by the control unit 23 to attract and hold the wafer W from the chuck table 3 and collect it, and places it on the cleaning table 51 of the cleaning unit 15. At this time, since the center of the chuck table 3 and the center of the cleaning table 51 are positioned on the turning trajectory of the wafer recovery unit 17, the center of the wafer W is aligned with the center of the cleaning table 51.

  The cleaning table 51 is formed in a disk shape having a smaller diameter than the wafer W. When the processed wafer W is placed on the cleaning table 51, the cleaning table 51 is lowered into the base 2 through the opening 52. The cleaning table 51 cleans the wafer W by spraying cleaning water while rotating at a high speed. Thereafter, the cleaning table 51 is rotated at a high speed, and the spray of cleaning water is stopped to dry the wafer W.

  The chuck table 3 is formed in a disk shape, and has a suction surface 27 for sucking and holding the wafer W on the upper surface. The suction surface 27 is formed of a porous ceramic material and is connected to a suction source (not shown) disposed in the base 2. Further, the suction surface 27 has a shape in which a portion corresponding to the orientation flat 71 is cut out along the outer shape of the wafer W. The orientation of the chuck table 3 is defined by the orientation of the portion corresponding to the orientation flat 71.

  The chuck table 3 is connected to a rotation drive mechanism (not shown) and is configured to be rotatable by the rotation drive mechanism. When the wafer W is placed by the wafer supply unit 16, the chuck table 3 is rotationally driven by the rotational drive mechanism so that the suction surface 27 is aligned with the orientation of the wafer W.

  A grinding unit moving mechanism 54 that moves the grinding unit 4 in the vertical direction is provided on the front surface of the support column 22. The grinding unit moving mechanism 54 includes a pair of parallel guide rails 55 extending in the vertical direction, and a motor-driven Z-axis table 56 slidably installed on the pair of guide rails 55. A nut portion (not shown) is formed on the back side of the Z-axis table 56, and a ball screw 57 is screwed to the nut portion. A drive motor 58 is connected to one end of the ball screw 57, and the ball screw 57 is rotationally driven by the drive motor 58.

  The grinding unit 4 is supported on the front surface of the Z-axis table 56 via a support portion 53. The grinding unit 4 has a grinding wheel 59 that is detachably attached to the lower end of a spindle (not shown). The grinding wheel 59 is made of, for example, a diamond grindstone in which diamond abrasive grains are hardened with a binder such as metal bond or resin bond. Then, the grinding unit 4 grinds the wafer W on the chuck table 3 while ejecting a grinding liquid from a nozzle (not shown).

  In this case, the surface of the wafer W held on the chuck table 3 that is in contact with the suction surface 27 is formed to be uneven. However, in the chuck table 3, the gap between the wafer W and the suction surface 27 is sealed by the surface tension of the grinding liquid, so that a reduction in the suction force of the suction surface 27 is suppressed and the wafer W is appropriately held.

  The control unit 23 performs calculation processing of the center position of the wafer W and the formation position of the orientation flat 71 by the detection unit 14, alignment processing of the wafer W by the wafer supply unit 16, and orientation processing for the wafer W by the chuck table 3. Execute the process. The control unit 23 includes a processor that executes various processes, a memory, and the like. The memory is composed of one or a plurality of storage media such as a ROM (Read Only Memory) and a RAM (Random Access Memory) depending on the application. The memory stores an orthogonal plane coordinate system (see FIG. 9) for image data together with a control program for each process.

  With reference to FIG. 2, the detection part which is the characterizing part of this invention is demonstrated in detail. FIG. 2 is an enlarged view around the detection unit 14 of the grinding apparatus 1 according to the present embodiment.

  As illustrated in FIG. 2, the detection unit 14 detects the center position of the wafer W and the formation position of the orientation flat 71 by imaging the outer peripheral edge of the wafer W on the temporary placement table 35 with the imaging unit 36. . The temporary placement table 35 is formed with a diameter smaller than that of the wafer W, and is rotated intermittently at a predetermined angular interval by a rotating portion 61 provided inside the base 2. The output shaft 62 of the rotation unit 61 is connected to the temporary placement table 35 at the upper end, and a slit disk 63 is attached to the intermediate portion.

  A part of the slit disk 63 is interposed between a light emitting element and a light receiving element of a photo interrupter 67 provided inside the base 2. A slit encoder 63 and a photo interrupter 67 constitute a rotary encoder 68, and the rotary encoder 68 detects the rotational position of the rotating unit 61. The signal detected by the rotary encoder 68 is output to the control unit 23, and the rotation of the temporary placement table 35 by the rotation unit 61 is controlled. In this embodiment, a transmissive rotary encoder is used, but a reflective rotary encoder may be used.

  The support surface 64 of the temporary placement table 35 is formed of a friction material 65 having a predetermined thickness. The friction material 65 is made of, for example, a closed-cell rubber sponge such as natural rubber, chloroprene rubber, or ethylene rubber. For this reason, the wafer W sinks moderately with respect to the support surface 64 due to its own weight, and can receive a sufficient frictional force from the support surface 64. In this case, the frictional force of the support surface 64 is set larger than the centrifugal force or inertial force that acts on the wafer W due to intermittent rotation of the temporary placement table 35. In particular, the wafer W having an uneven surface has a large contact area with the support surface 64 due to sinking with respect to the friction material 65, and positional displacement on the temporary placement table 35 is effectively prevented.

Note that the friction material 65 only needs to have a thickness enough to sink the wafer W, and is preferably 1.5 mm or more, for example. Further, the material of the friction material 65 is not limited to the above-described material, and any material may be used as long as it can apply a frictional force to the wafer W so as to prevent positional displacement. In particular, with respect to the friction material 65 that supports the wafer W of 8 to 12 inches, in consideration of the weight of the wafer W, the hardness is 0.1 to 0.25 g / cm ³ and the hardness using an ASKER C type measuring instrument. Is preferably 5 to 15 degrees, and the 25% compression load specified by ASTM D1056 satisfies 10 to 50 g / cm ² .

  The imaging unit 36 is supported above the temporary placement table 35 via the L-shaped support arm 66 as described above, and positions the imaging range at the outer peripheral edge of the wafer W. The imaging unit 36 images the wafer W in accordance with intermittent rotation of the temporary placement table 35 at predetermined angular intervals, and acquires imaging data and actual measurement data described later. The imaging data indicates the position of the outer peripheral edge of the wafer W at each stop angle of the temporary placement table 35 set at regular intervals, and the measured data indicates the position of the outer peripheral edge of the wafer W as the temporary placement table 35 rotates. It shows a change.

  The imaging data and actual measurement data output from the imaging unit 36 are used by the control unit 23 to calculate the center position of the wafer W and the formation position of the orientation flat 71. As described above, the detection unit 14 according to the present embodiment prevents the positional displacement of the wafer W in the horizontal direction with respect to the temporary placement table 35 due to the frictional force of the support surface 64, and the imaging unit 36 detects the outer peripheral edge of the wafer W. Images can be taken with high accuracy. Therefore, unlike the vacuum-type temporary placement table, the detection unit 14 can prevent the positional deviation of the wafer W without providing a suction source, and thus can have a simple device configuration.

  Hereinafter, the calculation processing of the center position of the wafer W and the formation position of the orientation flat 71 will be described in detail with reference to FIGS. In the following description, the calculation processing of the center position of the wafer W and the formation position of the orientation flat 71 is merely an example, and may be calculated by any method. In the following description, the imaging unit is described as a CCD line sensor.

  FIG. 3 is an explanatory diagram of processing for acquiring imaging data and actual measurement data by the imaging unit 36 included in the grinding apparatus 1 according to the present embodiment. In FIG. 3, the alternate long and short dash line indicates the imaging range Ec of the imaging unit 36, and the alternate long and two short dashes line indicates the stop angle of the temporary placement table.

  As shown in FIG. 3, the outer peripheral edge portion of the wafer W placed on the temporary placement table 35 is positioned in the imaging range Ec of the imaging unit 36. The imaging unit 36 detects and outputs the position (the coordinates of the CCD line sensor) of the outer peripheral edge of the wafer W positioned in the imaging range Ec. Therefore, the imaging unit 36 acquires the imaging data and the actual measurement data over the entire circumference of the outer peripheral edge of the wafer W by imaging the wafer W in the imaging range Ec while intermittently rotating the temporary placement table 35. .

  In the present embodiment, the temporary placement table 35 is intermittently rotated at intervals of 24 degrees with reference to the rotation angle (0 degrees) of the initial position of the wafer W. The imaging unit 36 acquires the position of the outer peripheral edge of the wafer W at each stop angle of the temporary placement table 35 as imaging data. In parallel with this, the imaging unit 36 acquires, as actual measurement data, a change in the position of the outer peripheral edge of the wafer W passing through the imaging range Ec when the temporary placement table 35 is rotated.

  When the imaging data and the actual measurement data are acquired, the calculation process of the center position of the wafer W is performed as shown in FIGS. FIG. 4 is an explanatory diagram of the calculation processing of the center position of the wafer W. FIG. 5 is another explanatory diagram of the calculation process of the center position of the wafer W. FIG. 6 is another explanatory diagram of the calculation process of the center position of the wafer W. In FIG. 4, a two-dot chain line indicates the stop angle of the temporary placement table 35, and in FIG. 5, a one-dot chain line indicates a virtual circle.

  As shown in FIG. 4, the control unit 23 acquires imaging data P1 to P15 that indicate the positions of the outer peripheral edge portions of the wafer W at each stop angle every 24 degrees, and the wafer W is used using these imaging data P1 to P15. The center position of is calculated. Specifically, the control unit 23 calculates a center position (temporary center position) of a circle determined by the three points of each set, with three sets of 15-degree intervals of 15 points P1 to P15 as one set. For example, as shown in FIG. 5, in the set of P5, P10, and P15, the temporary center position O1 of the virtual circle indicated by the alternate long and short dash line is calculated. The control unit 23 also performs this process for each of the other groups, and calculates the temporary center positions O1 to O5 for each of the five groups as shown in FIG.

  Next, the control unit 23 calculates the center position of the wafer W based on the calculated temporary center positions O1 to O5. The control unit 23 excludes the calculated temporary center positions O1 to O5 that are largely out of position because they are considered to have been calculated including points on the orientation flat 71. For example, the set of P5, P10, and P15 illustrated in FIG. 6 includes a point P15 on the orientation flat 71. The temporary center position of this set of virtual circles is significantly different from the temporary center positions of other sets of virtual circles that do not include the orientation flat 71. For this reason, the control unit 23 compares all the temporary center positions and excludes two sets of temporary center positions greatly deviating from other temporary center positions.

  Specifically, as illustrated in FIG. 6, the control unit 23 excludes the temporary center positions O1 and O5 that are greatly deviated from the temporary center positions O2, O3, and O4 among the temporary center positions O1 to O5. Thereby, the center position of the wafer W is calculated excluding the points P14 and P15 on the orientation flat 71. Here, two sets of temporary center positions to be excluded are used, but this number can be changed as appropriate according to the size of the irregularly shaped portion, the interval of the stop angle, and the like. Then, the control unit 23 calculates the center of gravity of these three sets of temporary center positions O2, O3, and O4 and sets them as the center position of the wafer W.

  When the center position of the wafer W is calculated, the control unit 23 generates reference data serving as a reference when detecting the formation position of the orientation flat 71. FIG. 7 is a diagram illustrating an example of the reference data.

  As shown in FIG. 7, the control unit 23 generates reference data using points excluding the points on the orientation flat 71 (three sets of nine points used to calculate the temporary center positions O2, O3, and O4). To do. Specifically, for each group, a change in position when the position on the circumference of the virtual circle determined by the three points is positioned in the imaging range of the imaging unit 36 is calculated. In this case, since the temporary center position of each set of virtual circles is slightly eccentric with respect to the rotation center of the temporary placement table 35, a sin curve is obtained. Then, the sin curves created for each of the three sets are averaged to obtain reference data shown in FIG. The reference data indicates a change in position when the wafer W is formed in a circular shape not including the orientation flat 71.

  Next, the control unit 23 detects the formation position of the orientation flat 71 by comparing the calculated reference data with the above-described actual measurement data. FIG. 8 is an explanatory diagram of the calculation processing of the orientation flat formation position. In FIG. 8, a solid line W1 indicates reference data, a one-dot chain line W2 indicates actual measurement data, and a two-dot chain line W3 indicates a difference value between the reference data and actual measurement data.

  As described above, the actual measurement data indicates the position change of the outer peripheral edge of the wafer W including the orientation flat 71. The controller 23 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. Then, the angle range L in which the calculated difference value exceeds the preset expression position Th with respect to the scale 0 of the difference value is detected as the formation position of the orientation flat 71. The orientation of the wafer W is detected from the orientation flat formation position (angle range).

  With reference to FIG. 9, the positioning operation of the position and orientation of the wafer with respect to the chuck table will be described. FIG. 9 is an explanatory diagram of the positioning operation of the position and orientation of the wafer W with respect to the chuck table 3 included in the grinding apparatus 1 according to the present embodiment.

  As shown in FIG. 9, in the orthogonal plane coordinate system, the center coordinate C2 of the chuck table 3 stored in advance, the calculated center coordinate C1 of the wafer W, and the angle θ1 indicating the orientation of the wafer W are set. First, based on the difference between the center coordinate C2 of the chuck table 3 and the center coordinate C1 of the wafer W, the control unit 23 calculates the movement amount and the rotation amount of the rotation axis 41 of the wafer supply unit 16 in the front-rear direction. The rotation amount of the chuck table 3 is calculated based on the angle θ1 indicating the direction of the wafer W.

  Next, the wafer supply unit 16 moves upward by moving the rotating shaft 41 downward from the state of being positioned above the temporary placement table 35 and sucking and holding the wafer W by the suction holding unit 43. Next, the wafer supply unit 16 drives the rotation shaft 41 according to the movement amount and rotation amount of the rotation shaft 41 in the front-rear direction calculated by the control unit 23, so that the wafer W is positioned above the chuck table 3. Let At this time, the center position of the wafer W matches the center position of the chuck table 3.

  Next, the chuck table 3 is rotated by an angle θ1 from the initial state where the chuck table 3 is directed in the positive direction of the Y axis, and the orientation of the chuck table 3 is made coincident with the orientation of the wafer W. Next, the wafer supply unit 16 moves the rotation shaft 41 downward to release the suction of the suction holding unit 43. In this way, the center of the wafer W is aligned with the center of the chuck table 3, and the direction of the wafer W is aligned with the direction of the chuck table 3.

  Thus, since the wafer W is aligned with the chuck table 3 in a state where the orientation of the wafer W is aligned with the orientation of the chuck table 3, the wafer W is placed so as to match the suction surface 27 of the chuck table 3. Placed. Therefore, the orientation flat 71 formed on the wafer W and the portion of the suction surface 27 corresponding to the orientation flat 71 coincide with each other, and the suction force is prevented from being reduced due to the positional deviation between the wafer W and the suction surface 27.

  Here, the flow of the entire grinding operation by the grinding apparatus 1 will be described. First, the unprocessed wafer W is taken out from the cassette 6 by the loading / unloading arm 13 and temporarily placed on the temporary placement table 35. Next, the temporary placement table 35 is intermittently rotated, and the outer peripheral edge portion of the wafer W is imaged by the imaging unit 36. At this time, since the positional deviation of the wafer W is suppressed by the frictional force from the support surface 64, the outer peripheral edge portion of the wafer W is accurately imaged by the imaging unit 36. Next, the center position of the wafer W and the formation position of the orientation flat 71 are calculated based on the imaging result. Next, the center of the wafer W is positioned at the center of the chuck table 3 by the wafer supply unit 16 based on the center position of the wafer W.

  Next, the orientation of the wafer W is matched with the orientation of the chuck table 3 based on the formation position of the orientation flat 71. Next, the wafer W held on the chuck table 3 is ground to a predetermined thickness by the grinding unit 4 at the processing position. Next, the ground wafer W is transferred to the cleaning table 51 by the wafer recovery unit 17 at the transfer position. Next, the processed wafer W is cleaned by the cleaning table 51, and the wafer W is accommodated in the cassette 7 by the loading / unloading arm 13.

  As described above, according to the grinding apparatus 1 according to the present embodiment, not only a wafer having a flat surface but also a wafer W having irregularities on the surface, the wafer W is caused by the frictional force generated on the temporary placement table 35. Is properly maintained. Therefore, the wafer W is not displaced in the horizontal direction due to the intermittent rotation of the temporary placement table 35, and the center position of the wafer W and the formation position of the orientation flat 71 can be detected with high accuracy by the detection unit 14. Further, unlike the conventional vacuum-type temporary placement table 35, a suction source is not required, so that the manufacturing cost can be reduced as a simple device configuration.

  In the above-described embodiment, the detection unit 14 detects the center position of the wafer W having irregularities on the surface. However, the present invention is not limited to this configuration. The detection unit 14 may detect the center position of the flat wafer W having no unevenness on the surface. Even in such a wafer W, the displacement due to the rotation of the temporary placement table 35 is appropriately suppressed by the frictional force of the support surface.

  Further, in the above-described embodiment, the friction material of the temporary placement table 35 is configured to sink the wafer W with the rubber sponge, but is not limited to this configuration. As long as the friction material generates a frictional force that suppresses the positional deviation of the wafer W, the friction material may not cause the wafer W to sink.

  In the above-described embodiment, the friction material is configured to be provided on the entire upper surface of the temporary placement table 35. However, the configuration is not limited to this configuration. The friction material may be arranged in a ring shape on a part of the upper surface of the temporary placement table 35, for example, on the outer peripheral edge as long as the positional deviation of the wafer W can be suppressed.

  In the above embodiment, the rotation of the temporary placement table 35 is controlled based on the output of the rotary encoder 68. However, the present invention is not limited to this configuration. As long as the rotation part 61 is a structure which can output the rotation amount of the temporary placement table 35, it is good also as a structure which does not provide the rotary encoder 68 in the detection part 14. FIG.

  In the above-described embodiment, the detection unit 14 is configured to detect the center position of the wafer W and the formation position of the orientation flat 71 (the orientation of the wafer W). However, the present invention is not limited to this configuration. . The detection unit 14 may be configured to detect only one of the center position and orientation of the wafer W.

  In the above-described embodiment, the orientation flat 71 is exemplified and described as the irregularly shaped portion that defines the orientation of the wafer W. However, the present invention is not limited to this configuration. It is sufficient that the orientation of the wafer W can be specified at the outer peripheral edge of the wafer W, and a notch may be used instead of the orientation flat 71.

  Further, in the above-described embodiment, the holding means is configured by the chuck table 3, but is not limited to this configuration. The holding unit may have any configuration as long as the workpiece W can be held.

  The embodiment disclosed this time is illustrative in all respects and is not limited to this embodiment. The scope of the present invention is shown not by the above description of the embodiments but by the scope of the claims, and is intended to include all modifications within the meaning and scope equivalent to the scope of the claims.

  As described above, the present invention can reduce the manufacturing cost with a simple apparatus configuration, and suppress the positional deviation with respect to the rotating table even if the workpiece has irregularities on the surface. It has the effect of being able to detect with high precision, and is particularly useful for a grinding apparatus that can position the wafer at a predetermined position with respect to the chuck table when grinding the wafer.

1 Grinding equipment 2 Base 3 Chuck table (holding means)
4 Grinding unit (grinding means)
13 Loading / unloading arm 14 Detection unit (detection means)
DESCRIPTION OF SYMBOLS 15 Cleaning part 16 Wafer supply part 17 Wafer collection | recovery part 23 Control part 27 Suction surface 35 Temporary placement table (table)
36 Image pickup unit 54 Grinding unit moving mechanism 61 Rotating unit 63 Slit disk 64 Support surface 65 Friction material 67 Photo interrupter 68 Rotary encoder 71 Orientation flat W Wafer (work)

Claims (1)

A grinding apparatus comprising: a holding unit that holds a workpiece; a grinding unit that grinds the workpiece held by the holding unit; and a detection unit that detects at least the position of the workpiece before the workpiece is loaded into the holding unit. Because
The detection means includes
A table that supports the workpiece;
An imaging unit for imaging a workpiece supported by the table;
A rotating unit that rotates the table about a vertical direction as a rotation axis;
A rotary encoder that detects a rotational position of the rotating unit;
The support surface that supports the workpiece of the table is formed of a member that generates a frictional force that restricts displacement of the workpiece in the horizontal direction when the table is rotated by the rotating portion. Grinding equipment.

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