JP5823880B2 - Grinding method for plate - Google Patents

Description

  The present invention relates to a method for grinding a plate-like object by grinding a small plate-like object to a predetermined thickness.

  At the time of grinding a small plate-like object, an adhesive tape is attached so as to close the opening of the ring frame, and a plurality of small plate-like objects are carried into the grinding device while being attached to the adhesive tape. The plurality of plate-like objects carried into the grinding device are held on the chuck table via the adhesive tape and are brought into contact with the grinding surface of the grinding wheel rotated about the vertical axis. In this way, the plurality of plate-like objects are ground simultaneously by rotating and contacting the grinding surface of the grinding wheel and the upper surfaces (back surfaces) of the plurality of plate-like objects in a parallel state.

  Conventionally, as a grinding method for such a plate-like material, a method in which a wafer for thickness measurement is provided on an adhesive tape separately from the plate-like material to be ground is known (for example, see Patent Document 1). In the method for grinding a plate-like object described in Patent Document 1, a disk-shaped wafer is stuck to the center of an adhesive tape stretched on a ring frame, and a plurality of plate-like objects are stuck around the wafer. . In the grinding apparatus, the wafer and a plurality of plate-like objects are ground simultaneously, and the plate-like object is adjusted to a desired thickness by grinding while measuring the thickness of the wafer for measurement.

  Further, as a method for grinding such a plate-like object, a method in which a ring frame is formed of silicon for thickness measurement is known (for example, see Patent Document 2). In the method for grinding a plate-like object described in Patent Document 2, a thin silicon wafer is cut into a ring shape by a cutting device to form a ring-shaped wafer frame. An adhesive tape is attached to the wafer frame, and a plurality of plate-like objects are attached on the adhesive tape. In the grinding apparatus, the wafer frame and the plurality of plate-like objects are ground simultaneously, and the plate-like object is adjusted to a desired thickness by grinding while measuring the thickness of the wafer frame for measurement.

JP 2004-082319 A JP 2001-351890 A

  However, the grinding method of the plate-like material of Patent Document 1 has a disk-like wafer provided at the center of the adhesive tape, so that the space for attaching a small plate-like material is reduced and the productivity is deteriorated. There was a problem. Further, in the grinding method of the plate-like material of Patent Document 2, since the wafer frame for thickness measurement also functions as a ring frame, there is a possibility that the plate-like material cannot be properly held by the thinned wafer frame after grinding. was there. Further, since the wafer frame is formed by the cutting device and the wafer frame is discarded by one grinding, the cost is increased.

  The present invention has been made in view of the above points, and when grinding a small plate-like object, it is possible to adjust a plurality of plate-like objects to a desired thickness, further improving productivity and reducing cost. It aims at providing the grinding method of the plate-shaped object which can be reduced.

  The method for grinding a plate-like object according to the present invention comprises a chuck table that holds a plate-like object on its upper surface and is rotatable, a grinding means that includes a grinding wheel disposed so as to face the chuck table, A thickness measuring means for measuring the thickness of a held plate-like object, and a grinding method for a plate-like object for grinding a plate-like object to a predetermined thickness by using a grinding device constituted at least. A step of dividing the disk-shaped plate-like object into four equal pieces, and the divided sides of the plurality of fan-like pieces divided in the division step are alternately brought into contact with each other so that the outer circumferential arcs face each other. A straight line is formed to form a side, a quadrangle is formed by four sides, and the four corners are arranged in a semicircular shape, and a square shape is drawn so that a perfect circle can be drawn between the outer and inner peripheral edges of the side. Adhesive tape to unite multiple fan-shaped pieces An integral attaching step for attaching, a holding step for holding the intersection of the rectangular diagonal lines at the center of rotation of the chuck table and holding the chuck table; and a plurality of fan-like pieces held on the chuck table. A grinding step for grinding by a grinding means, wherein the thickness measuring means is positioned on a perfect circle drawn between the outer peripheral edge and the inner peripheral edge of the square shape, and the chuck table rotates to measure the thickness. The thickness of the plurality of fan-shaped pieces is detected by means.

  According to this configuration, a square is formed by the plurality of fan-shaped pieces, and the thickness of the fan-shaped pieces is measured by the thickness measuring unit on the perfect circle drawn in the quadrangle. For this reason, the thickness measuring means does not drop off from the fan-shaped pieces during grinding, and a plurality of plate-like objects (fan-shaped pieces) are simultaneously ground to a predetermined thickness while being measured by the thickness measuring means. Thus, since the measurement locus of the thickness measuring means is drawn on the plurality of fan-shaped pieces, there is no need to newly provide a member for measuring the thickness. Therefore, it is possible to secure a wide space for the fan-shaped piece on the adhesive tape to improve the productivity and reduce the cost.

  According to the present invention, when grinding a small plate-like object, a plurality of plate-like objects can be adjusted to a desired thickness, and the productivity can be improved and the cost can be reduced.

It is a top view of the plate-shaped object before the division | segmentation which concerns on this Embodiment. It is a top view of the several fan-shaped piece which concerns on this Embodiment. It is a figure which shows an example of the sticking method of the fan-shaped piece which concerns on this Embodiment. It is a perspective view which shows an example of the grinding device which concerns on this Embodiment. It is explanatory drawing which shows an example of the grinding process by the grinding apparatus which concerns on this Embodiment.

  Hereinafter, the present embodiment will be described with reference to the accompanying drawings. The plate-like object grinding method according to the present embodiment is a method in which a disc-like plate-like object is divided into fan-like pieces by a cutting device, and a plurality of fan-like pieces are annularly re-applied on an adhesive tape and then ground. It is a method of carrying in to an apparatus. Thereby, in the grinding apparatus, the measurement trajectory measured by the height gauge can be drawn on the upper surface of the plurality of fan-shaped pieces arranged in an annular shape, and the plurality of fan-shaped pieces can be formed without providing a separate measurement member. Grinding is possible at the same time. FIG. 1 is a top view of a plate-like object before division. FIG. 2 is a top view of a plurality of fan-shaped pieces arranged to form a quadrangle. FIG. 3 is a diagram illustrating an example of a method of attaching a fan-shaped piece.

As shown in FIG. 1, an adhesive tape 82 is attached to the lower surface of a metal ring frame 81, and a small plate-like object W is attached to the center of the adhesive tape 82. The plate-like object W is formed in a disk shape with a small diameter (for example, 1 to 3 inches) by a difficult-to-cut material. Note that the plate-like object W includes difficult cutting of ceramic, glass, sapphire (Al ₂ O ₃ ) -based inorganic material substrates, compound semiconductors, and the like. The plate-like object W may be a semiconductor wafer such as a silicon wafer or a gallium strain. Further, the plate-like object W is not limited to a small-diameter disk shape, and may be, for example, a rectangular small chip.

  The plate-like object W is carried into a dividing device (not shown) while being supported by the ring frame 81. The dividing device is a so-called dicing device, and divides the plate-like object W by cutting a circular cutting blade. In the dividing device, the plate-like object W is equally divided into four along the virtual line L to form four fan-shaped pieces W1 (dividing step). Note that the dividing device only needs to be able to divide the plate-like object W. For example, the dividing device may be a laser processing device that divides the plate-like object W by laser processing. In addition, the dividing device is not limited to a configuration in which a single plate-like object W is carried in a state in which the single plate-like object W is adhered to the adhesive tape 82, and a plurality of plate-like objects W are adhered to the adhesive tape 82. It may be brought in.

  The plate-like object W (fan-shaped piece W1) is peeled off from the adhesive tape 82 after being divided by the dividing device. For example, when the pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 82 is a UV curable adhesive, the pressure-sensitive adhesive property of the pressure-sensitive adhesive tape 82 is reduced by irradiating the pressure-sensitive adhesive tape 82 with UV light. Moreover, when the adhesive layer of the adhesive tape 82 is a thermosetting adhesive, the adhesiveness of the adhesive tape 82 is lowered by applying heat to the adhesive tape 82. The pressure-sensitive adhesive layer of the pressure-sensitive adhesive tape 82 is not limited to the UV curable adhesive and the thermosetting adhesive, and it is sufficient that the plate-like object W is detachably attached. Further, the plate-like object W may be fixed on a rigid plate such as glass instead of the adhesive tape 82.

  As shown in FIG. 2, the fan-shaped piece W1 peeled off from the adhesive tape 82 is again affixed on the adhesive tape 92 stretched on the ring frame 91 for carrying into the grinding apparatus 1 (integrated adhesion step). . Here, a total of 20 fan-shaped pieces W1 obtained by dividing five plate-like objects W into four are arranged on the adhesive tape 92 so as to form a square. Specifically, the linear division surfaces (sides) 93 of the fan-shaped pieces W1 are alternately brought into contact with each other, and the adjacent fan-shaped pieces W1 are arranged in the opposite direction. Thereby, the plurality of fan-shaped pieces W1 are linearly arranged so that the outer peripheral arcs 94 of the adjacent fan-shaped pieces W1 face each other, and a quadrangular four sides are formed.

  Further, at the four corners of the quadrangle, adjacent fan-shaped pieces W1 are arranged to be line-symmetric with respect to the dividing plane 93. Thereby, a corner | angular part is formed in the four corners of a square by the fan-shaped piece W1 arrange | positioned at semicircle shape. Thus, on the adhesive tape 92, a rectangular frame-shaped quadrilateral having a predetermined width is formed by arranging the plurality of fan-shaped pieces W1. An inner periphery and an outer periphery are formed in the quadrangle by outer peripheral arcs 94 of a plurality of fan-shaped pieces W1, and a width enough to draw a perfect circle C is secured between the inner periphery and the outer periphery. And in the grinding apparatus 1 mentioned later, the thickness of the several fan-shaped piece W1 is measured along this perfect circle C by the height gauge (thickness measurement means) 51. FIG.

  For example, as shown in FIG. 3, the fan-shaped piece W1 is attached to the adhesive tape 92 on a chuck table 75 of a tape mounter (not shown) using a template 72 in which a rectangular frame-shaped opening 71 is formed. Done in On the lower surface of the template 72, a film-like release ruled paper (mounting paper) (not shown) is attached. First, as shown in FIG. 3A, the template 72 is disposed on the suction surface 76 of the chuck table 75, and the template 72 is sucked and held on the suction surface 76 via the ruled paper. Further, around the suction surface 76, the ring frame 91 is held by a frame holding portion (not shown). In this case, the centers of the template 72 and the ring frame 91 are positioned at the center of the chuck table 75.

  Next, as shown in FIG. 3B, a plurality of fan-shaped pieces W <b> 1 are arranged along the opening edge of the template 72. At this time, the plurality of fan-shaped pieces W1 form a rectangular frame-like quadrangle, and are arranged so that a perfect circle C is drawn between the inner peripheral edge and the outer peripheral edge. Further, since the centers of the template 72 and the ring frame 91 coincide with each other, the center of the perfect circle C coincides with the center of the ring frame 91. Next, as shown in FIG. 3C, after removing the template 72 from the chuck table 75, an adhesive tape 92 is attached from above so as to cover the ring frame 91 and the plurality of fan-shaped pieces W1. Thereby, the ring frame 91 and the plurality of fan-shaped pieces W1 are integrated via the adhesive tape 92.

  Then, as shown in FIG. 3D, the plurality of fan-shaped pieces W1 attached to the adhesive tape 92 are removed from the chuck table 75, and the release sheet is peeled off, and then carried into the grinding apparatus 1. The above-described method of attaching the fan-shaped piece W1 to the adhesive tape 92 is an example, and the present invention is not limited to this method. The plurality of fan-shaped pieces W <b> 1 may be attached to the adhesive tape 92 so that the intersection of the square diagonal lines, that is, the center of the perfect circle C coincides with the rotation center of the chuck table 31. Further, the attaching operation of the fan-shaped piece W1 may be performed on the chuck table of the cutting device or the grinding device 1, or may be performed on a chuck table dedicated for attaching.

  A grinding apparatus according to the present embodiment will be described with reference to FIG. FIG. 4 is a perspective view showing an example of a grinding apparatus.

  As shown in FIG. 4, the grinding apparatus 1 rotates the chuck table 31 holding the plurality of fan-shaped pieces W1 and the grinding wheel 44 of the grinding unit (grinding means) 4 to rotate the fan-shaped pieces W1. It is configured to grind. The grinding device 1 has a substantially rectangular parallelepiped base 2. On the upper surface of the base 2, there is provided a turntable 3 on which a pair of chuck tables 31 (only one is shown) are arranged. A wall portion 21 that supports the grinding unit 4 is erected on the rear side of the turntable 3. Further, inside the base 2, a control unit 5 that controls each part of the grinding device 1 is provided.

  The turntable 3 is formed in the shape of a large-diameter disk, and a pair of chuck tables 31 are arranged on the upper surface at point-symmetrical positions around the rotation axis. The turntable 3 is connected to a rotation drive mechanism (not shown), and is intermittently rotated by the rotation drive mechanism at intervals of 180 degrees in the direction of the arrow D1. For this reason, the pair of chuck tables 31 are moved between a repositioning position where a plurality of fan-like pieces W1 are carried in and out and a grinding position facing the grinding unit 4.

  The chuck table 31 is formed in a disk shape with a small diameter, and is rotatably provided on the upper surface of the turntable 3. At the center of the upper surface of the chuck table 31, an adsorption surface 32 is formed of a porous ceramic material. An annular magnet 33 is provided around the chuck table 31. Since the ring frame 91 around the plurality of fan-shaped pieces W1 is formed of a magnetic material, it is attracted and fixed by the annular magnet 33.

  On the upper surface of the base 2, a height gauge 51 is provided in the vicinity of the grinding position of the turntable 3. The height gauge 51 has one contact 52 that can contact the upper surface of the plurality of fan-shaped pieces W1 arranged in a rectangular frame shape. The height gauge 51 measures the thickness of the fan-shaped piece W1 by bringing the tip of the contact 52 into contact with the upper surfaces of the plurality of fan-shaped pieces W1. As described above, since the plurality of fan-shaped pieces W1 are arranged in a rectangular frame shape with the rotation center of the chuck table 31 as the center, the measurement trajectory having a perfect circle shape is formed on the upper surface of the plurality of fan-shaped pieces W1 by the tip of the contactor 52. Is drawn.

  In this case, a minute gap may be formed at the boundary between the plurality of fan-shaped pieces W1, but the tip of the contactor 52 is rounded to such an extent that no drop into the gap occurs. Therefore, the thickness of the fan-shaped piece W1 is accurately measured over the entire circumference of the plurality of fan-shaped pieces W1 arranged in a rectangular frame shape. The measurement value obtained by the height gauge 51 is input to the control unit 5 through the transmission path. The height gauge 51 only needs to be able to measure the thickness of the fan-shaped piece W1, and may be, for example, a non-contact type height gauge.

  The wall 21 is provided with a grinding unit moving mechanism 6 that moves the grinding unit 4 up and down. The grinding unit moving mechanism 6 includes a pair of guide rails 61 arranged in front of the wall portion 21 and parallel to the Z-axis direction, and a motor-driven Z-axis table 62 slidably installed on the pair of guide rails 61. Have. The grinding unit 4 is supported on the front surface of the Z-axis table 62. On the back surface of the Z-axis table 62, a nut portion protruding rearward through the opening 22 of the wall portion 21 is provided.

  A ball screw provided on the back surface of the wall portion 21 is screwed into the nut portion of the Z-axis table 62. Then, the grinding motor 4 is moved along the guide rail 61 in the Z-axis direction when the drive motor 64 connected to one end of the ball screw is rotationally driven. In this case, the movement position of the grinding unit 4 in the Z-axis direction is measured by a linear scale (not shown) and input to the control unit 5 through the transmission path. The control unit 5 controls the movement amount of the grinding unit 4 with high accuracy based on the measurement value from the linear scale and the measurement value from the height gauge 51.

  The grinding unit 4 is provided with a mount 42 at the lower end of a cylindrical spindle 41. The mount 42 is equipped with a grinding wheel 44 to which a plurality of grinding wheels 43 are fixed. The grinding wheel 43 is composed of, for example, a diamond wheel in which diamond abrasive grains are hardened with a binder such as metal bond or resin bond. The grinding wheel 43 is rotated at high speed around the Z axis as the spindle 41 is driven. And the grinding surface 45 (refer FIG. 5) of the grinding wheel 43 and the upper surface of the several fan-shaped piece W1 are rotationally contacted in a parallel state, and the several fan-shaped piece W1 is ground simultaneously.

  With reference to FIG. 5, the grinding process by the grinding apparatus according to the present embodiment will be described. FIG. 5 is an explanatory view showing an example of grinding by the grinding apparatus.

  As shown in FIG. 5A, when the plurality of fan-shaped pieces W1 are held on the chuck table 31 via the adhesive tape 92, the ring frame 91 is fixed by the annular magnet 33 around the chuck table 31 (holding step). . At this time, an intersection of square diagonal lines formed by the plurality of fan-shaped pieces W <b> 1 is positioned at the rotation center of the chuck table 31. The ring frame 91 is fixed at a position lower than the suction surface 32 of the chuck table 31 so as not to interfere with the grinding wheel 43 during grinding.

  Next, as shown in FIG. 5B, the contact 52 of the height gauge 51 is brought into contact with the upper surface 95 of the fan-shaped piece W1, and the thickness measurement of the fan-shaped piece W1 is started. In this case, the surface position of the chuck table 31 is first measured by the height gauge 51, and the thickness of the fan-shaped piece W1 is measured based on the surface position. Further, since the center of the quadrangle formed by the plurality of fan-shaped pieces W1 is aligned with the center of rotation of the chuck table 31, the contact 52 is placed on a perfect circle C (see FIG. 2) between the inner and outer peripheral edges of the quadrangle. Is positioned.

  Next, as shown in FIG. 5C, when the grinding unit 4 is driven, the spindle 41 and the chuck table 31 are rotated. In this case, since the measurement locus of the contact 52 overlaps with the perfect circle C, the contact 52 does not fall off from the upper surface 95 of the fan-shaped piece W1. Then, the grinding wheel 43 is brought close to the chuck table 31 while rotating, and the grinding surface 45 of the grinding wheel 43 is pressed against the upper surfaces 95 of the plurality of fan-shaped pieces W1 to perform grinding (grinding step). In this case, the grinding wheel 43 contacts the fan-shaped piece W1 at a position eccentric with respect to the rotation center of the chuck table 31, and therefore does not cover the entire plurality of fan-shaped pieces W1. Thus, since the upper surfaces 95 of the plurality of fan-shaped pieces W1 are partially exposed from the grinding wheel 43, the contact 52 can be brought into contact with the exposed surface of the fan-shaped pieces W1 during grinding. Yes.

  At this time, the thickness of the fan-shaped piece W1 is measured by the height gauge 51 in real time. The measured value of the height gauge 51 is fed back to the control unit 5 through the transmission line. In the control unit 5, the processing feed amount of the grinding unit 4 is controlled so that the measured value fed back from the height gauge 51 approaches the final finished thickness of the fan-shaped piece W1, which is the target thickness. When the measured value from the height gauge 51 matches the finished thickness of the fan-shaped piece W1, the grinding process by the grinding unit 4 is stopped. Thus, by grinding while measuring the thickness of the plurality of fan-shaped pieces W1, the plurality of fan-shaped pieces W1 are formed in a desired finished thickness.

  Here, the flow of the plate-like object grinding method according to the present embodiment will be described. As described above, the disk-shaped plate-like object W is carried into the dividing device while being supported by the ring frame 81 via the adhesive tape 82. In the dividing device, the plate-like object W is divided into four to form four fan-shaped pieces W1 (dividing step). Each fan-shaped piece W1 is peeled off from the adhesive tape 82 and carried into the tape mounter by curing the adhesive layer of the adhesive tape 82 with UV light or the like. In the tape mounter, a plurality of fan-shaped pieces W1 are attached to the adhesive tape 92 for the grinding apparatus 1 so as to form a square on the chuck table 75 using the template 72 (integrated attaching step).

  In the integral attaching step, a plurality of fan-shaped pieces W1 are arranged along the opening edge of the template 72, and the plurality of fan-shaped pieces W1 are arranged so as to form a rectangular frame-shaped square. At this time, a width is secured such that a perfect circle C is drawn between the inner periphery and the outer periphery of the quadrangle. Then, after removing the template 72 from the chuck table 75, the ring frame 91 and the plurality of fan-shaped pieces W1 are integrated through the adhesive tape 92 by the tape mounter. A plurality of fan-shaped pieces W1 integrated by the adhesive tape 92 are carried into the grinding apparatus 1.

  In the grinding apparatus 1, the plurality of fan-shaped pieces W <b> 1 are arranged at the center of rotation of the chuck table 31 so that the intersection of square diagonal lines formed by the plurality of fan-shaped pieces W <b> 1, that is, the center of the perfect circle C is positioned at the center of rotation of the chuck table 31. (Holding step). In the plurality of fan-shaped pieces W1, the tips of the contacts 52 of the height gauge 51 are positioned on the perfect circle C drawn on the upper surface 95, and the thickness measurement of the fan-shaped pieces W1 is started. Then, by controlling the grinding unit 4 according to the measured value of the height gauge 51, the plurality of fan-shaped pieces W1 are ground to a desired finished thickness (grinding step).

  As described above, according to the grinding method according to the present embodiment, a square is formed by the plurality of fan-shaped pieces W1, and the thickness of the fan-shaped piece W1 is measured by the height gauge 51 on the perfect circle C drawn in the square. Is done. For this reason, the height gauge 51 does not fall off from the fan-shaped piece W1 during the grinding process, and the plurality of fan-shaped pieces W1 are simultaneously ground to a predetermined thickness while being measured by the height gauge 51. Thus, since the measurement locus of the height gauge 51 is drawn on the upper surface 95 of the plurality of fan-shaped pieces W1, it is not necessary to provide a new member for measuring the thickness. Therefore, a wide space for the fan-shaped piece W1 can be secured on the adhesive tape 92 to improve productivity, and cost can be reduced.

  In addition, this invention is not limited to the said embodiment, It can change and implement variously. In the above-described embodiment, the size, shape, and the like illustrated in the accompanying drawings are not limited to this, 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-described embodiment, the disk-like plate W is divided into four parts to form the fan-like pieces W1, but for example, the plate-like object W is divided into eight pieces to form the fan-like pieces W1. The fan-shaped pieces W1 may be arranged on the adhesive tape 92 so as to form a quadrangle.

  Moreover, in the said embodiment, although the fan-shaped piece W1 was arrange | positioned so that the center part of the adhesive tape 92 might be vacant, even if it arrange | positions the fan-shaped piece W1 also in the center part of the adhesive tape 92, or the outer side of a rectangle. Good.

  Moreover, in the said embodiment, although the several fan-shaped piece W1 was affixed on the adhesive tape 92 so that a square might be formed, it is not limited to this structure. The plate-like object W is divided into a plurality of pieces, the plurality of pieces are arranged in an annular shape, and the plurality of pieces are attached to the adhesive tape 92 so that a perfect circle C can be drawn between the outer peripheral edge and the inner peripheral edge of the annular portion. It may be affixed to. Even with such a configuration, the productivity of the plate-like object W can be improved and the cost can be reduced as in the present embodiment.

  As described above, the present invention has an effect that a plurality of plate-like objects can be adjusted to a desired thickness, and the productivity can be improved and the cost can be reduced. This is useful for a method of grinding a plate-like material that is thinned to a predetermined thickness.

1 Grinding device 4 Grinding unit (grinding means)
31 Chuck table 44 Grinding wheel 51 Height gauge (thickness measuring means)
52 Contact Element 72 Template 71 Opening 91 Ring Frame 92 Adhesive Tape 93 Dividing Surface (Side)
94 Peripheral arc W Plate-like object W1 Fan-like piece

Claims (1)

A chuck table that holds a plate-like object on its upper surface and is rotatable, a grinding means having a grinding wheel disposed opposite to the chuck table, and a thickness of the plate-like object held on the chuck table are measured. Thickness measuring means, and a grinding method for a plate-like material to finish a predetermined thickness by grinding a plate-like material using a grinding device comprising at least
A dividing step of dividing a plurality of disk-shaped plates into four equal fan-shaped pieces;
The divided sides of the plurality of fan-shaped pieces divided in the dividing step are arranged in a straight line so that the outer peripheral arcs face each other in a staggered fashion, form a side, form a quadrangle by four sides, and form four corners. Are arranged in a semicircular shape, and a single sticking step of sticking a plurality of fan-like pieces together in a square shape to the adhesive tape so that a perfect circle can be drawn between the outer peripheral edge and the inner peripheral edge of the side;
A holding step in which the intersection of the rectangular diagonal lines is positioned at the center of rotation of the chuck table and held on the chuck table;
A grinding step of grinding a plurality of fan-shaped pieces held on the chuck table by the grinding means,
In the grinding step, the thickness measuring means is positioned in a perfect circle drawn between the outer peripheral edge and the inner peripheral edge of the quadrangular shape, and the chuck table rotates and the thickness measuring means detects the thickness of the plurality of fan-shaped pieces. To
A method for grinding a plate-like object.

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