JP2012121096A - Grinding device - Google Patents

Abstract

Disclosed is a grinding device capable of suppressing the displacement of a workpiece due to rotation of a holding table and accurately detecting the position of the workpiece.
A holding table 8a in a detecting means of a grinding apparatus includes a base portion 8g having a suction port 8l at the center of the upper surface, and an annular member 8h disposed on the base portion 8g so as to surround the suction port 8l. A central member 8i disposed inside the annular member 8h on the base portion 8g, and the annular member 8h is non-breathable and elastic, and is a protective tape adhered to the surface of the workpiece W. The thickness is sufficient to absorb unevenness, and the central member 8i is configured to have air permeability and elasticity.
[Selection] Figure 3

Description

  The present invention relates to a grinding apparatus capable of positioning a workpiece at a predetermined position with respect to a chuck table when grinding a workpiece (workpiece) such as a semiconductor wafer.

  In the semiconductor device manufacturing process, devices such as IC and LSI are formed in each of a plurality of areas defined by division lines arranged in a lattice pattern on the surface of a substantially disk-shaped workpiece, and then the workpiece is processed by a grinding machine. The back surface is ground to process the workpiece into a predetermined thickness, and the ground workpiece is divided into individual chips by cutting along the planned division line.

  In the grinding apparatus, the workpiece is positioned in a predetermined direction and position, is carried into the chuck table, and the workpiece is ground by relative rotation between the chuck table holding the workpiece and the grinding wheel. In the work, a notch called an orientation flat or orientation notch indicating a crystal orientation is formed on the outer peripheral edge, and the direction of the work is specified by this notch.

  2. Description of the Related Art Conventionally, there has been proposed a grinding apparatus provided with detection means for detecting the orientation and position of a workpiece before carrying the workpiece into a chuck table (see, for example, Patent Document 1). The detection means rotates the work held on the holding table by the vacuum method, and sequentially picks up the outer peripheral edge of the work by the image pickup means to detect the position and orientation of the work.

JP 2010-147134 A

  If a plurality of protrusions called bumps are formed on the work surface, the surface irregularities may not be completely absorbed even if a protective tape is applied to the work surface. In this case, when the work is placed on the holding table made of conventional ceramic or metal of the detection device with the surface on which the bump is formed facing downward, a gap is formed between the work surface (tape surface) and the holding table. For this reason, the suction force on the vacuum type holding table does not sufficiently act, and the workpiece is displaced in the horizontal direction due to the rotation of the holding 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 an object of the present invention is to provide a grinding apparatus that can suppress the displacement of the workpiece due to the rotation of the holding table and can accurately detect the position of the workpiece.

  In the grinding apparatus of the present invention, a protective tape is attached to a work surface having a plurality of electrodes protruding from the surface, and the holding means for holding the work via the protective tape attached to the surface; and the holding A grinding apparatus comprising: grinding means for grinding a work held by the means from the back side; and detection means for detecting a center position of the work before carrying the work into the holding means, wherein the detection means A holding table that holds the workpiece, a rotating unit that rotates the holding table about a vertical direction of the holding table, and an imaging unit that images the outer periphery of the workpiece held by the holding table. The holding table includes a base portion having a suction port at the center of the upper surface, an annular member disposed on the base portion so as to surround the suction port, and the annular portion on the base portion. A central member disposed on the inside of the annular member, wherein the annular member has air permeability and elasticity and has a thickness capable of absorbing irregularities of the protective tape adhered to the work surface. The member is characterized by air permeability and elasticity.

  According to this grinding apparatus, the holding table in the detection means of the grinding apparatus includes a base portion having a suction port at the center of the upper surface, an annular member disposed on the base portion so as to surround the suction port, A central member disposed inside the annular member on the base portion, and the annular member has air permeability and elasticity, and the unevenness of the protective tape adhered to the work surface Since the central member has air permeability and elasticity, the surface of the holding table is deformed along the surface shape of the workpiece when the workpiece is placed, and the workpiece has irregularities on the surface. Even so, the work is properly held in the holding table. Further, since the central member has air permeability, the suction force in the vacuum type holding table generated between the workpiece and the central member acts appropriately. Therefore, the position shift of the work due to the rotation of the holding table can be suppressed, and the position of the work can be detected with high accuracy.

  ADVANTAGE OF THE INVENTION According to this invention, the position shift of the workpiece | work by rotation of a holding table can be suppressed, and the grinding apparatus which can detect the position of a workpiece | work accurately can be provided.

1 is an external perspective view of a grinding apparatus according to an embodiment. It is the (a) perspective view of a part of detection means in a grinding device, and (b) an exploded perspective view. It is a cross-sectional schematic diagram which shows the relationship between the holding table in a detection means, and a workpiece | work. It is explanatory drawing of the acquisition process of the imaging data by the imaging means in a detection means, and measurement data. It is explanatory drawing of the calculation process of the workpiece | work center position in a grinding device. It is explanatory drawing of the calculation process of the workpiece | work center position in a grinding device. It is explanatory drawing of the calculation process of the workpiece | work center position in a grinding device. It is a figure which shows an example of the reference data in a grinding device. It is explanatory drawing of the calculation process of the orientation flat formation position in a grinding device. It is explanatory drawing of the positioning operation | movement of the workpiece | work position and direction with respect to the chuck | zipper table in a grinding device.

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 the present embodiment. In the following description, an example in which the detection means that is a characteristic part of the present invention is applied to a grinding apparatus will be described. However, for example, it may be applied to other processing apparatuses that position the orientation and center position of a workpiece on a chuck table. Is possible.

  As shown in FIG. 1, the grinding apparatus 1 relatively rotates the chuck table 2 holding the workpiece W with the surface on which a plurality of electrodes (bumps) are formed facing downward, and the grinding wheel 3 a of the grinding unit 3, The workpiece W is configured to be ground on the back surface.

  Here, the workpiece | work W which is a workpiece of the grinding apparatus 1 is demonstrated. The workpiece W is formed in a substantially disc shape, and division lines are arranged in a lattice pattern on the surface, and devices (not shown) are formed in each of a plurality of regions partitioned by the division lines. Bumps (not shown) are formed so as to protrude from the surface of the workpiece W as terminals for connecting these devices and the substrate. The bumps are arranged on the surface of the work W with a predetermined interval, and form irregularities on the surface of the work W. Further, a protective tape for protecting the device at the time of grinding the back surface of the workpiece W is attached to the surface of the workpiece W. In addition, an orientation flat OF indicating a crystal orientation is formed on the outer peripheral edge of the workpiece W.

In the present embodiment, a semiconductor wafer such as a silicon wafer will be described as an example of the workpiece W. However, the workpiece W is not particularly limited. For example, silicon (Si), gallium arsenide (GaAs) is used. , Semiconductor wafers such as silicon carbide (SiC), ceramic, glass, sapphire (Al ₂ O ₃ ) based inorganic material substrates, ductile materials of sheet metal and resin, and flatness of micron order to submicron order ( Various processing materials that require TTV (Total Thickness Variation) may be used as the workpiece W.

  The grinding device 1 has a substantially rectangular parallelepiped base 4, and the base 4 is provided with a pair of cassette mounting portions 5 a and 5 b that protrude from the front surface 4 a in the Y-axis direction. The cassette placing portion 5a functions as a carry-in entrance, and a carry-in cassette 6a that accommodates the workpiece W before processing is placed thereon. Further, the cassette placing portion 5b functions as a carry-out port, and a carry-out cassette 6b that accommodates the processed workpiece W is placed thereon.

  On the base 4, a loading / unloading arm 7 for loading and unloading the workpiece W with respect to the cassettes 6a and 6b is installed facing the cassette mounting portions 5a and 5b. The carry-in / carry-out arm 7 includes a multi-node link mechanism 7a having a wide driving area and a holding portion 7b provided at the tip of the multi-node link mechanism 7a. The carry-in / carry-out arm 7 drives the multi-joint link mechanism 7a to carry the work W accommodated in the carry-in cassette 6a into the detection unit 8, and from the cleaning unit 9 into the carry-out cassette 6b. To accommodate.

  On one side of the carry-in / carry-out arm 7, a detection unit 8 is provided as detection means for detecting the center position of the workpiece W before processing and the orientation flat OF. The detection unit 8 includes a holding table 8a that holds the workpiece W loaded by the loading / unloading arm 7, an imaging unit 8b that functions as an imaging unit that images the workpiece W held on the holding table 8a, and a Z-axis direction (vertical direction). And a rotating part 8c (not shown in FIG. 1, refer to FIG. 2) for rotating the holding table 8a. The holding table 8a is formed in a disc shape, and is connected to a suction source that sucks and holds the workpiece W. The outer diameter of the holding table 8a is set to be approximately the same as the outer diameter of the workpiece W. Furthermore, when the work W is placed, the surface of the holding table 8a is deformed along the surface shape of the work W due to elasticity.

  The imaging unit 8b is supported above the holding table 8a via an L-shaped support arm 8d. The imaging unit 8b sequentially images the outer peripheral edge of the workpiece W in accordance with the intermittent rotation of the holding table 8a. The imaging unit 8b is configured by an imaging device (CCD) or the like, and sends a captured image signal to the control unit 10 to detect the center position of the workpiece W and the formation position of the orientation flat OF.

  On the other side of the carry-in / carry-out arm 7, a cleaning unit 9 for cleaning the processed workpiece W is provided. The cleaning unit 9 includes a disk-shaped cleaning table 9 a having a smaller diameter than the workpiece W. When the processed workpiece W is placed, the cleaning table 9a descends into the base 4 through the opening 9b, and cleans the workpiece W by rotating at a high speed in a state where the cleaning liquid is jetted. Dry the workpiece W.

  Between the detection unit 8 and the cleaning unit 9, a workpiece supply unit 11 that supplies the workpiece W before processing to the chuck table 2 and a workpiece collection unit 12 that collects the workpiece W after processing from the chuck table 2 are provided. It has been. The workpiece supply unit 11 includes a rotary shaft 11a extending in the Z-axis direction, a swing arm 11b supported on the upper end of the rotary shaft 11a, and a suction holding unit that sucks and holds the workpiece W provided at the tip of the swing arm 11b. 11c. The rotation shaft 11a is provided so as to be movable in the Y-axis and Z-axis directions and to be rotatable around the Z-axis. The movement amount in the Y-axis and Z-axis directions and the rotation amount around the Z-axis are controlled by the control unit 10. The The suction holding portion 11c can adjust the position in the horizontal plane by moving the rotary shaft 11a in the Y-axis direction and rotating around the Z-axis, and can adjust the position in the height direction by moving the rotary shaft 11a in the Z-axis direction. The workpiece supply unit 11 sucks and holds the workpiece W from the holding table 8 a and lifts it and places it on the chuck table 2. At this time, since the center of the holding table 8 a and the center of the chuck table 2 are positioned on the turning locus of the workpiece supply unit 11, the center of the workpiece W is aligned with the center of the chuck table 2.

  The workpiece collection unit 12 has substantially the same configuration as the workpiece supply unit 11, sucks and holds the workpiece W from the chuck table 2, and places it on the cleaning table 9 a. At this time, since the center of the chuck table 2 and the center of the cleaning table 9a are located on the turning trajectory of the workpiece collection unit 12, the center of the workpiece W is aligned with the center of the cleaning table 9a.

  On the base 4, a rectangular opening 13 extending in the Y-axis direction is provided adjacent to the workpiece supply unit 11 and the workpiece collection unit 12. The opening 13 is covered with a movable plate 14 that can move together with the chuck table 2 and a bellows-shaped waterproof cover 15. Below the waterproof cover 15, a ball screw type moving mechanism (not shown) for moving the chuck table 2 in the Y-axis direction is provided. The chuck table 2 reciprocates between a transfer position where the workpiece W is transferred by the workpiece supply unit 11 and the workpiece recovery unit 12 and a processing position where the workpiece W is ground by the grinding unit 3 by this moving mechanism. Moving.

  On the moving plate 14, a chuck table 2 as a holding means is installed. The chuck table 2 is formed in a disc shape and includes a work holding portion 2a that holds the work W by suction. The work holding part 2a is made of, for example, a porous ceramic material, and is connected to a suction source (not shown) installed in the base 4. Further, the workpiece holding portion 2a is set to a shape in which a portion corresponding to the orientation flat OF is cut out along the outer shape of the workpiece W. Thereby, the direction of the chuck table 2 is defined. Further, the chuck table 2 is configured to be rotatable by a rotation driving mechanism (not shown). Thus, when the workpiece W is placed by the workpiece supply unit 11, the chuck table 2 is rotationally driven so that the orientation of the workpiece holding unit 2a is aligned with the orientation flat OF of the workpiece W.

  On the base 4, a support column 16 is erected adjacent to the opening 13. The support column 16 is provided with a pair of Z-axis guide rails 17 a and 17 b formed in the Z-axis direction. Yes. The Z-axis table 18 is installed so as to be movable in the Z-axis direction along the Z-axis guide rails 17a and 17b. A nut portion (not shown) is formed on the back surface portion of the Z-axis table 18, and a ball screw 19 is screwed to the nut portion. A drive motor 20 is connected to the end of the ball screw 19, and the ball screw 19 is rotationally driven by the drive motor 20.

  The Z-axis table 18 supports a grinding unit 3 as a grinding means via a support portion 21. A grinding wheel 3a is detachably mounted on the grinding unit 3 at the lower end of a spindle (not shown). The grinding wheel 3a 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. The grinding unit 3 grinds the workpiece W held on the chuck table 2 while ejecting a grinding liquid from a nozzle (not shown). At this time, since the gap between the workpiece W and the workpiece holding portion 2a is sealed by the surface tension of the grinding fluid, even if irregularities are formed on the surface of the workpiece W in contact with the workpiece holding portion 2a, the workpiece holding portion 2a W can be held appropriately.

  The control unit 10 is configured by hardware resources such as a CPU, a ROM, and a RAM, and the CPU reads control software stored in the ROM and executes processing according to the program. The control unit 10 performs processing such as processing for calculating the center position of the workpiece W and the orientation flat OF formation position by the detection unit 8, processing for positioning the workpiece W by the workpiece supply unit 11, and processing for facing the workpiece W by the chuck table 2. Execute. In addition to the control software, the ROM and RAM also store an orthogonal plane coordinate system (see FIG. 10) for image data.

  Next, the detection unit 8 in the grinding apparatus 1 will be described in detail. FIG. 2 is a (a) perspective view and (b) exploded perspective view of a part of the detection unit 8 in the grinding apparatus 1.

The holding table 8a includes a base portion 8g having a suction port 8l at the center of the upper surface, an annular member 8h disposed on the base portion 8g so as to surround the suction port 8l, and an annular member 8h on the base portion 8g. And a central member 8i disposed inside. The annular member 8h has air permeability and elasticity, and can absorb the bumps on the surface of the work W and the thickness of the protective tape that covers the bumps, that is, the unevenness of the protective tape attached to the surface of the work W. The thickness is set to about 1.0 mm, for example. The annular member 8h is made of, for example, a closed-cell rubber sponge made of natural rubber, chloroprene rubber, ethylene propylene rubber, or the like. In particular, it is desirable to use a material having a density of 0.1 to 0.25 [g / cm ³ ] and a hardness of 5 to 15 degrees as measured with an ASKER C type measuring instrument. When such an annular member 8h is used, the workpiece W that comes into contact with the annular member 8h when placed on the holding table 8a receives an appropriate frictional force from the annular member 8h. The outer diameter of the annular member 8h is set to be substantially the same as the outer diameter of the base portion 8g, and the inner diameter of the annular member 8h is set to be substantially the same as the outer diameter of the central member 8i.

On the other hand, the central member 8i has air permeability and elasticity, and is set to have a thickness similar to that of the annular member 8h or about 1.0 mm thick. The central member 8i is made of, for example, an open-cell sponge made of polyurethane (PU) or the like as a raw material. In particular, it is desirable to use a material having a density of 0.1 to 0.25 [g / cm ³ ] and a hardness of 5 to 15 degrees as measured with an ASKER C type measuring instrument. An example of such a sponge is Soflas (registered trademark) sponge having a density of 0.21 [g / cm ³ ] and a hardness measured by an ASKER C type measuring instrument of 11 degrees. If the cell of the open cells of the sponge constituting the central member 8i is too large, the sponge collapses at the time of vacuum, so that a space is created between the central member 8i and the workpiece W, and the surface of the workpiece W and the holding table 8a There is a possibility that the surface does not adhere. On the other hand, if the cell of the sponge open bubbles constituting the central member 8i is too small, the sponge does not deform along the surface shape of the workpiece W when the workpiece W is placed, and the surface of the workpiece W and the surface of the holding table 8a May not adhere. Therefore, it is desirable to employ a sponge having the above density and hardness as an open cell sponge having cells of an appropriate size.

  Here, the relationship between the holding table 8a and the workpiece W will be described with reference to FIG. FIG. 3 is a schematic cross-sectional view showing the relationship between the holding table 8 a and the workpiece W in the detection unit 8. As shown in FIG. 3A, a plurality of bumps 30 are formed on the surface of the work W, and the protective tape 31 covers the work W surface and the bumps 30. In the holding table 8a, the thickness of the central member 8i is set to be thicker than the annular member 8h. This is because the central member 8i is more likely to sink due to its own weight than the annular member 8h disposed at the outer edge.

  As shown in FIG. 3B, when the workpiece W is placed on the holding table 8a, the central member 8i and the annular member 8h are deformed along the surface shape of the workpiece W due to elasticity. Therefore, the surface of the workpiece W and the surface of the holding table 8a are in close contact with each other without a gap. In this state, when the workpiece W is sucked by the suction source through the suction port 8l, the workpiece W is adsorbed only by the central member 8i portion having air permeability. As a result, the frictional force generated between the workpiece W and the annular member 8h and the suction force in the vacuum type holding table 8a generated between the workpiece W and the central member 8i act appropriately. The horizontal displacement of the workpiece W due to the rotation can be suppressed.

  The rotating unit 8c rotates the holding table 8a intermittently at a predetermined angular interval via the output shaft 8e. The rotary encoder 8f includes a slit disk 8j and a photo interrupter 8k, and detects the rotational position of the rotating unit 8c. A part of the slit disk 8j is interposed between the light emitting element and the light receiving element of the photo interrupter 8k. The rotary encoder 8f sends the detected signal to the control unit 10, whereby the rotation of the holding table 8a by the rotating unit 8c is controlled. In the present embodiment, the rotary encoder 8f is a transmissive type, but may be a reflective type.

  The imaging unit 8b in the detection unit 8 is supported above the holding table 8a via the L-shaped support arm 8d as described above, and positions the imaging range at the outer peripheral edge of the workpiece W. The imaging unit 8b images the workpiece W in accordance with intermittent rotation of the holding table 8a at predetermined angular intervals, and acquires imaging data and actual measurement data. The imaging data indicates the position of the outer peripheral edge of the workpiece W at each stop angle of the holding table 8a set at a constant interval. The actual measurement data indicates a change in the position of the outer peripheral edge of the workpiece W accompanying the rotation of the holding table 8a.

  The imaging data and actual measurement data output from the imaging unit 8b are used by the control unit 10 for calculating the center position of the workpiece W and the formation position of the orientation flat OF. Since the detection member 8 according to the present embodiment has the elastic annular member 8h and the central member 8i arranged on the surface of the holding table 8a, the detection unit 8 is held along the surface shape of the workpiece W when the workpiece W is placed. Deformation of the surface of the table 8a prevents the workpiece W from being displaced in the horizontal direction. Therefore, the outer peripheral edge portion of the workpiece W can be accurately imaged by the imaging unit 8b while intermittently rotating the holding table 8a.

  Hereinafter, the calculation process of the center position of the workpiece W and the formation position of the orientation flat OF will be described in detail with reference to FIGS. In the following description, the calculation processing of the center position of the workpiece W and the formation position of the orientation flat OF is merely an example, and may be calculated by any method. In the following description, the imaging unit 8b in the detection unit 8 will be described as a CCD line sensor.

  FIG. 4 is an explanatory diagram of the acquisition process of the imaging data and the actual measurement data by the imaging unit 8b included in the grinding apparatus 1 according to the present embodiment. In FIG. 4, the alternate long and short dash line indicates the imaging range Ec of the imaging unit 8b, and the alternate long and two short dashes line indicates the stop angle of the holding table 8a.

  As shown in FIG. 4, the outer peripheral edge of the workpiece W placed on the holding table 8a is positioned in the imaging range Ec of the imaging unit 8b. The imaging unit 8b detects and outputs the position (the coordinates of the CCD line sensor) of the outer peripheral edge of the workpiece W positioned in the imaging range Ec. Therefore, the imaging unit 8b acquires imaging data and actual measurement data over the entire circumference of the outer peripheral edge of the workpiece W by imaging the workpiece W in the imaging range Ec while intermittently rotating the holding table 8a.

  In the present embodiment, the holding table 8a is intermittently rotated at intervals of 24 ° with reference to the rotation angle (0 °) of the initial position of the workpiece W. The imaging unit 8b acquires the position of the outer peripheral edge of the workpiece W at each stop angle of the holding table 8a as imaging data. In parallel with this, the imaging unit 8b acquires, as actual measurement data, a change in the position of the outer peripheral edge of the workpiece W that passes through the imaging range Ec when the holding table 8a rotates.

  When the imaging data and the actual measurement data are acquired, the calculation process of the center position of the workpiece W is performed as shown in FIGS. FIG. 5 is an explanatory diagram of the calculation processing of the center position of the workpiece W. FIG. 6 is another explanatory diagram of the calculation processing of the center position of the workpiece W. FIG. 7 is another explanatory diagram of the calculation processing of the center position of the workpiece W. In FIG. 5, a two-dot chain line indicates the stop angle of the holding table 8a, and in FIG. 6, a one-dot chain line indicates a virtual circle.

  As shown in FIG. 5, the control unit 10 acquires imaging data P1 to P15 indicating the position of the outer peripheral edge of the workpiece W at each stop angle every 24 °, and uses the imaging data P1 to P15 to obtain the workpiece W. The center position of is calculated. Specifically, the control unit 10 sets 15 points P1 to P15 at 120 ° intervals as one set, and calculates the center position (temporary center position) of a circle determined by the three points of each set. For example, as shown in FIG. 6, 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 10 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 10 calculates the center position of the workpiece W based on the calculated temporary center positions O1 to O5. The control unit 10 considers that the calculated temporary center positions O1 to O5 whose position greatly deviates are calculated including the points on the orientation flat OF, and based on the data used for the calculation processing of the center position of the workpiece W. The point of is excluded. For example, since the set of P5, P10, and P15 shown in FIG. 7 includes the point P15 on the orientation flat OF, the temporary center position O1 is determined from the temporary center positions of the other virtual circles that do not include the orientation flat OF. Deviate greatly. The same applies to the set of P4, P9, and P14. For this reason, the control unit 10 compares all the temporary center positions, and uses two sets of temporary center positions O1 and O5 greatly deviated from the temporary center positions O2, O3, and O4 for the calculation process of the center position of the workpiece W. Exclude from

  As a result, the center position of the workpiece W is calculated excluding the points P14 and P15 on the orientation flat OF. 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 controller 10 uses the remaining three sets of temporary center positions O2, O3, and O4, calculates the center of gravity of these, and sets it as the center position of the workpiece W.

  When the center position of the workpiece W is calculated, the control unit 10 generates reference data serving as a reference when detecting the formation position of the orientation flat OF. FIG. 8 is a diagram illustrating an example of the reference data.

  As shown in FIG. 8, the control unit 10 generates reference data using points (three sets of nine points used to calculate the temporary center positions O2, O3, and O4) excluding the points on the orientation flat OF. To do. Specifically, the position change 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 8b is calculated for each group. 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 holding table 8a, 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 workpiece W is formed in a circular shape not including the orientation flat OF.

  Next, the control unit 10 detects the formation position of the orientation flat OF by comparing the calculated reference data with the above-described actual measurement data. FIG. 9 is an explanatory diagram of the calculation process of the formation position of the orientation flat OF. In FIG. 9, the solid line W1 indicates the reference data, the alternate long and short dash line W2 indicates the actual measurement data, and the alternate long and two short dashes line W3 indicates the difference value between the reference data and the actual measurement data.

  As described above, the actual measurement data indicates a change in the position of the outer peripheral edge of the workpiece W including the orientation flat OF. The control unit 10 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, an angle range L in which the calculated difference value exceeds a threshold value Th set in advance with respect to the scale 0 of the difference value is detected as a formation position of the orientation flat OF. The direction of the workpiece W is detected from the formation position (angle range) of the orientation flat OF.

  With reference to FIG. 10, the positioning operation | movement of the position and direction of the workpiece | work W with respect to the chuck table 2 which the grinding apparatus 1 which concerns on this Embodiment has is demonstrated. FIG. 10 is an explanatory diagram of the positioning operation of the position and orientation of the workpiece W with respect to the chuck table 2 included in the grinding apparatus 1 according to the present embodiment.

  As shown in FIG. 10, in the orthogonal plane coordinate system, a center coordinate C2 of the chuck table 2 stored in advance, a calculated center coordinate C1 of the workpiece W, and an angle θ1 indicating the orientation of the workpiece W are set. First, based on the difference between the center coordinate C2 of the chuck table 2 and the center coordinate C1 of the workpiece W by the control unit 10, the movement amount of the rotation axis 11a of the workpiece supply unit 11 in the Y-axis direction and the rotation amount around the Z axis are determined. In addition to the calculation, the rotation amount of the chuck table 2 is calculated based on the angle θ1 indicating the direction of the workpiece W.

  Next, the workpiece supply unit 11 moves (lowers) the rotating shaft 11a in the −Z-axis direction from the position above the holding table 8a and sucks and holds the workpiece W by the suction holding unit 11c. Move in the direction (up). Next, the workpiece supply unit 11 drives the rotary shaft 11 a according to the amount of movement of the rotary shaft 11 a in the Y-axis direction and the amount of rotation about the Z-axis calculated by the control unit 10, and moves the workpiece W to the chuck table 2. Position it above. At this time, the center position of the workpiece W and the center position of the chuck table 2 coincide with each other.

  Next, the chuck table 2 is rotated by an angle θ1 from the initial state facing the Y-axis direction, and the orientation of the chuck table 2 is matched with the orientation of the workpiece W. Next, the workpiece supply unit 11 moves (lowers) the rotating shaft 11a in the −Z-axis direction to release the suction of the suction holding unit 11c. In this way, the center of the workpiece W is aligned with the center of the chuck table 2, and the direction of the workpiece W is aligned with the direction of the chuck table 2.

  Thus, since the workpiece W is aligned with the chuck table 2 in a state where the orientation of the workpiece W is aligned with the orientation of the chuck table 2, the workpiece W matches the workpiece holding portion 2 a of the chuck table 2. Placed. Accordingly, the orientation flat OF formed on the workpiece W and the portion corresponding to the orientation flat OF in the workpiece holding portion 2a coincide with each other, and it is possible to prevent the adsorption force from being lowered due to the positional deviation between the workpiece W and the workpiece holding portion 2a. The

  Next, the flow of grinding by the grinding apparatus 1 according to the present embodiment will be described. First, the workpiece W before processing is unloaded from the cassette 6 a by the loading / unloading arm 7 and placed on the holding table 8 a in the detection unit 8. Next, the holding table 8a is intermittently rotated, and the outer peripheral edge of the workpiece W is imaged by the imaging unit 8b. At this time, since the surface of the holding table 8a is deformed along the surface shape of the workpiece W due to the elasticity of the surface of the holding table 8a, the horizontal displacement of the workpiece W is prevented, and accurate imaging by the imaging unit 8b is realized. it can. Next, the center position and orientation of the workpiece W are calculated based on the imaging result, and based on this result, the workpiece W center coincides with the chuck table 2 center and the workpiece holding portion 2a coincides with the workpiece holding portion 2a. The workpiece W is aligned by the supply unit 11.

  Next, the workpiece W held on the chuck table 2 is ground to a predetermined thickness by the grinding unit 3 at the machining position. After the grinding process is completed, the workpiece W is placed on the cleaning table 9a of the cleaning unit 9 by the workpiece recovery unit 12 at the transfer position. After completion of the cleaning process, the workpiece W is carried out from the washing table 9a by the carry-in / carry-out arm 7 and accommodated in the cassette 6b.

  As described above, according to the grinding apparatus 1 according to the present embodiment, the holding table 8a in the detection unit 8 of the grinding apparatus 1 includes the base part 8g having the suction port 8l at the center of the upper surface, and the base part 8g. And a central member 8i disposed inside the annular member 8h on the base portion 8g, the annular member 8h being non-breathable. It has a thickness that can absorb the unevenness of the protective tape that is attached to the surface of the work W and has elasticity, and the central member 8i has air permeability and elasticity. Therefore, when the work W is placed, the surface shape of the work W The surface of the holding table 8a is deformed along and the workpiece W is appropriately held by the holding table 8a even if the workpiece W has irregularities on the surface. Moreover, since the central member 8i has air permeability, the suction force in the vacuum type holding table 8a generated between the workpiece W and the central member 8i acts appropriately. As a result, the horizontal displacement of the workpiece W during rotation of the holding table 8a can be prevented. Therefore, the outer peripheral edge portion of the workpiece W can be imaged with high accuracy by the imaging unit 8b while intermittently rotating the holding table 8a, and the position of the workpiece can be detected with high accuracy.

  In addition, this invention is not limited to the said embodiment, It can implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited thereto, and can be appropriately changed within a range in which the effect of the present invention is exhibited. In addition, various modifications can be made without departing from the scope of the object of the present invention.

  For example, in the above embodiment, bumps are formed on the workpiece W and the surface of the workpiece W has irregularities. However, the present invention is not limited to this configuration. Even if the surface of the workpiece W has no irregularities, the surface of the holding table 8a having elasticity when the workpiece W is placed is deformed, whereby the horizontal displacement of the workpiece W during rotation of the holding table 8a. Can be prevented.

  In the above embodiment, the outer diameter of the holding table 8a is substantially the same as the outer diameter of the workpiece W, that is, the outer diameter of the annular member 8h is set to be substantially the same as the outer diameter of the workpiece W. However, the present invention is not limited to this configuration. Since the holding table 8a only needs to be able to suck and hold the workpiece W, the outer diameter of the workpiece W may be set larger than the inner diameter of the annular member 8h. Of course, the outer diameter of the holding table 8a may be set smaller than the outer diameter of the workpiece W. With such a configuration, the same holding table 8a can be used for workpieces W of different sizes, and the biting of foreign matter between the workpiece W and the holding table 8a is reduced. be able to.

  In the above embodiment, the rotation of the holding table 8a is controlled based on the output of the rotary encoder 8f. However, the present invention is not limited to this configuration. As long as the rotation part 8c can output the rotation amount of the holding table 8a, the rotary encoder 8f may be omitted.

  Moreover, in the said embodiment, although it was set as the structure which detects the center position of the workpiece | work W, and the formation position (direction of the workpiece | work W) of the orientation flat OF by the detection part 8, this invention is not limited to this structure. Absent. The detection unit 8 may be configured to detect only one of the center position or orientation of the workpiece W.

  Moreover, in the said embodiment, although orientation flat OF was illustrated and demonstrated as an irregular shape part which prescribes | regulates the direction of the workpiece | work W, this invention is not limited to this structure. It is only necessary that the direction of the workpiece W can be specified at the outer peripheral edge of the workpiece W. For example, an orientation notch may be provided.

  As described above, the present invention can suppress the displacement of the workpiece due to the rotation of the holding table and can accurately detect the position of the workpiece. Therefore, the present invention is not limited to the above-described grinding apparatus, and performs various processes such as grinding and laser machining. Applicable to processing equipment.

DESCRIPTION OF SYMBOLS 1 Grinding apparatus 2 Chuck table 2a Work holding part 3 Grinding unit 3a Grinding wheel 4 Base 4a Front surface 5a, 5b Cassette mounting part 6a, 6b Cassette 7 Loading / unloading arm 7a Multi-node link mechanism 7b Holding part 8 Detection part 8a Holding table 8b Imaging unit 8c Rotating unit 8d Support arm 8e Output shaft 8f Rotary encoder 8g Base unit 8h Ring member 8i Central member 8j Slit disk 8k Photo interrupter 8l Suction port 9 Cleaning unit 9a Cleaning table 9b Opening unit 10 Control unit 11 Work supply 11 Part 12 Work collection part 11a Rotating shaft 11b Swivel arm 11c Suction holding part 13 Opening part 14 Moving plate 15 Waterproof cover 16 Supporting part 19 Ball screw 20 Drive motor 21 Support part 30 Bump 31 Protective tape W Work OF Orientation frame Door

Claims (1)

A protective tape is attached to the work surface having a plurality of electrodes protruding from the surface, and holding means for holding the work via the protective tape attached to the surface;
Grinding means for grinding the workpiece held by the holding means from the back side;
A detecting device for detecting a center position of the workpiece before carrying the workpiece into the holding device,
The detection means includes
A holding table for holding the workpiece;
A rotating unit that rotates the holding table around the vertical direction of the holding table;
Imaging means for imaging the outer periphery of the work held by the holding table;
The holding table is
A base having a suction port in the center of the upper surface;
An annular member disposed on the base portion so as to surround the suction port;
A central member disposed inside the annular member on the base, and
The annular member has air permeability and elasticity and has a thickness capable of absorbing irregularities of the protective tape adhered to the work surface, and the central member has air permeability and elasticity. apparatus.

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