Measuring fixture

Abstract

To provide a measuring jig that makes it possible to easily measure a change in the height of a holding surface and a reference surface of a chuck table on a to-be-measured line by using a dial gauge without dropping a measuring element of the dial gauge in a groove formed in the chuck table.SOLUTION: There is provided a measuring jig provided with a main body portion capable of continuously connecting a holding surface and a reference surface of a chuck table. When a change in the height of a to-be-measured line of the holding surface and the reference surface of the chuck table is measured by a dial gauge, the measurement jig is disposed so that the to-be-measured line overlaps the main body portion. In other words, the holding surface and the reference surface are continuously connected to each other via an upper surface of the main body portion on the to-be-measured line.SELECTED DRAWING: Figure 1

Description

[Technical field]

[0001] The present invention relates to a measuring tool used when measuring a change in height of a line to be measured on a chuck table using a dial gauge. [Background technology]

[0002] Semiconductor device chips such as ICs (Integrated Circuits) and LSIs (Large Scale Integration) are essential components in various electronic devices such as mobile phones and personal computers. Such chips are manufactured, for example, by forming a large number of devices on the surface of a workpiece such as a wafer made of a semiconductor material, and then dividing the workpiece into regions containing individual devices.

[0003] Furthermore, the workpiece is often thinned to a desired thickness before being divided in order to reduce the size and weight of the chip, improve heat dissipation, etc. Such thinning of the workpiece is performed, for example, by grinding the back side of the workpiece in a grinding device.

[0004] The grinding device has a holding surface (upper surface) shaped to correspond to the side surface of the cone, and is equipped with a chuck table that can rotate around a straight line passing through the center of the holding surface as a rotation axis. Also, above the chuck table, a grinding unit is provided that has a spindle to the tip of which an annular grinding wheel can be attached.

[0005] The grinding wheel includes an annular wheel base and a plurality of grinding stones, each having a rectangular parallelepiped shape, which are arranged at intervals along the circumferential direction of the wheel base. A pair of thickness measuring devices (e.g., a pair of height gauges) are provided near the chuck table to measure the thickness of the workpiece being ground.

[0006] When thinning a workpiece with this grinding device, first the front side of the workpiece is held on the holding surface of the chuck table, and then one of the probes is brought into contact with the holding surface of the chuck table and the other probe is brought into contact with the back side of the workpiece so that the thickness of the workpiece can be calculated by a pair of thickness gauges.

[0007] Next, while both the chuck table and the spindle with the grinding wheel attached to its tip are rotated, the grinding surfaces (lower surfaces) of each of the multiple grinding wheels are brought into contact with the back surface (upper surface) of the workpiece, and the back surface of the workpiece is ground until the thickness of the workpiece reaches a specified thickness.

[0008] However, when the workpiece is thinned by grinding in this way, the rigidity of the workpiece is reduced, and the workpiece is more likely to be damaged by the external force applied to the workpiece when it is transported. In light of this, it has been proposed to form a work unit by integrating the workpiece and a ring frame via a tape, and then grind the workpiece contained in this work unit to thin it (see, for example, Patent Document 1).

[0009] In this case, the workpiece can be transported while supported by the ring frame, reducing the likelihood of the workpiece being damaged. A groove is formed on the holding surface of the chuck table of the grinding device used to grind the workpiece included in the work unit. In this grinding device, the workpiece is ground with the ring frame positioned inside the groove so that the grinding of the workpiece is not hindered by the ring frame.

[0010] In addition, in this grinding device, the workpiece is ground with the entire holding surface of the chuck table covered with the tape included in the work unit. Therefore, in order to accurately measure the thickness of the workpiece being ground using a pair of thickness gauges in this grinding device, it is necessary to bring one of the gauge heads into contact with a surface (reference surface) located outside the groove, and the other gauge head into contact with the back surface of the workpiece. [Prior art documents] [Patent documents]

[0011] [Patent Document 1] JP 2011-42003 A Summary of the Invention [Problem to be solved by the invention]

[0012] In the grinding device described above, the holding surface and reference surface of the chuck table are ground (self-grinded) so that the holding surface has a shape corresponding to the side of a cone. After self-grinding, the change in height of the holding surface and reference surface along a measured line is measured to confirm the shape of the holding surface and reference surface of the chuck table. The measured line is, for example, a curved area that overlaps with the rotation trajectory of multiple grinding wheels that perform self-grinding of the chuck table.

[0013] This measurement is performed by moving the dial gauge along the measured line while keeping the dial gauge in contact with the measured line on the holding surface and the reference surface. For example, this measurement is performed by rotating the spindle with the dial gauge attached to it so that the track of the track when the spindle is rotated overlaps with the rotation tracks of multiple grinding wheels.

[0014] However, in the chuck table of the grinding machine described above, a groove is formed between the holding surface and the reference surface. If the measuring point of the dial gauge falls into this groove, the measuring point may come into contact with the bottom or side of the groove and be damaged. Therefore, when performing this measurement, the operator needs to rotate the spindle while supporting the dial gauge by hand as appropriate so that the measuring point does not fall into the groove. However, such a measurement is cumbersome.

[0015] In view of this, an object of the present invention is to provide a measuring tool that makes it possible to easily measure changes in height at the measured line on the holding surface and reference surface of a chuck table using a dial gauge without dropping the probe of the dial gauge into a groove formed in the chuck table. [Means for solving the problem]

[0016] According to one aspect of the present invention, a work unit is obtained by integrating a ring frame and a workpiece positioned at an opening of the ring frame with a tape, the work unit having a holding surface for holding the workpiece via the tape, a reference surface that is positioned outside the ring frame when the workpiece is held on the holding surface via the tape, an inner surface extending downward from the outer edge of the holding surface, an outer surface extending downward from the inner edge of the reference surface, and a bottom surface that extends from the lower end of the inner surface to the lower end of the outer surface, and the ring frame is positioned inside when the workpiece is held on the holding surface via the tape. and a groove for receiving the groove through the holding surface of a chuck table, the holding surface including the groove being inserted into the holding surface and the upper end of the outer surface of the chuck table. The measuring jig is used when measuring a change in height at a measured line between the holding surface and the reference surface by using a dial gauge, the measuring jig comprising: a first engagement portion for engaging with an outer edge portion of the holding surface and an upper end portion of the inner surface; a second engagement portion for engaging with an inner edge portion of the reference surface and an upper end portion of the outer surface of the chuck table; and a main body portion connecting the first engagement portion and the second engagement portion, wherein when the first engagement portion engages with the outer edge portion of the holding surface and the upper end portion of the inner surface and the second engagement portion engages with the inner edge portion of the reference surface and the upper end portion of the outer surface of the chuck table, the main body portion continuously connects the holding surface and the reference surface.

[0017] According to another aspect of the present invention, there is provided a chuck table including a holding surface for holding, via the tape, a workpiece of a work unit obtained by integrating a ring frame and a workpiece positioned in an opening of the ring frame with a tape, a reference surface positioned outside the ring frame when the workpiece is held on the holding surface via the tape, and a groove having an inner side extending downward from the outer edge of the holding surface, an outer side extending downward from the inner edge of the reference surface, and a bottom surface extending from the lower end of the inner side to the lower end of the outer side, and into which the ring frame is positioned when the workpiece is held on the holding surface via the tape, the chuck table being used when measuring, with a dial gauge, a change in height along a measured line between the holding surface and the reference surface. a measuring jig for use in a measuring instrument comprising a first bridge section, a second bridge section, and a connecting section connecting the first bridge section and the second bridge section, each of the first bridge section and the second bridge section comprising a first engagement section for engaging with an outer edge section of the holding surface and an upper end section of the inner side surface, a second engagement section for engaging with an inner edge section of the reference surface and an upper end section of the outer side surface, and a main body section connecting the first engagement section and the second engagement section, wherein when the first engagement section of each of the first bridge section and the second bridge section engages with the outer edge section of the holding surface and the upper end section of the inner side surface, and the second engagement section engages with the inner edge section of the reference surface and the upper end section of the outer side surface, the main body section of each of the first bridge section and the second bridge section continuously connects the holding surface and the reference surface, and the connecting section is positioned inside the groove.

[0018] According to yet another aspect of the present invention, there is provided a measuring tool used when using a dial gauge to measure a change in height at a measured line between the holding surface of a chuck table and the reference surface, the measuring tool including: a holding surface for holding, via the tape, a workpiece of a work unit obtained by integrating a ring frame and a workpiece positioned in an opening of the ring frame by adhering a tape to the ring frame and the workpiece; a reference surface positioned outside the ring frame when the workpiece is held on the holding surface via the tape; and a groove having an inner surface extending downward from an outer edge of the holding surface, an outer surface extending downward from the inner edge of the reference surface, and a bottom surface extending from a lower end of the inner surface to a lower end of the outer surface, the ring frame being positioned inside the groove when the workpiece is held on the holding surface via the tape, the measuring tool including: a connecting portion connecting the first bridge portion and the second bridge portion and having a scale formed thereon, each of the first bridge portion and the second bridge portion comprising a first engagement portion for engaging with an outer edge portion of the holding surface and an upper end portion of the inner surface, a second engagement portion for engaging with an inner edge portion of the reference surface and an upper end portion of the outer surface, and a main body portion connecting the first engagement portion and the second engagement portion, wherein when the first engagement portion of each of the first bridge portion and the second bridge portion engages with the outer edge portion of the holding surface and the upper end portion of the inner surface, and the second engagement portion engages with the inner edge portion of the reference surface and the upper end portion of the outer surface, each of the main body portions of the first bridge portion and the second bridge portion continuously connects the holding surface and the reference surface, and the connecting portion is positioned such that the scale is displayed along the measured line. Effect of the Invention

[0019] The measuring jig of the present invention is provided with a main body that can continuously connect the holding surface of the chuck table and the reference surface, and when measuring the change in height of the measured line on the holding surface of the chuck table and the reference surface with a dial gauge, the measuring jig is disposed so that the measured line overlaps with the main body.

[0020] In other words, the holding surface and the reference surface are continuously connected via the upper surface of the main body at the line to be measured. Therefore, by using the measuring jig of the present invention, it is possible to easily measure the change in height of the holding surface of the chuck table and the reference surface at the line to be measured by using this dial gauge without dropping the probe of the dial gauge into a groove formed in the chuck table. [Brief description of the drawings]

[0021] [Figure 1] FIG. 1 is a perspective view illustrating an example of a measuring jig. [Diagram 2] FIG. 2(A) is a perspective view that typically shows an example of how the measuring tool is used, and FIG. 2(B) is a top view that typically shows an example of how the measuring tool is used. [Diagram 3] 3(A) and 3(B) are each a perspective view that typically shows another example of the measuring jig. [Figure 4] FIG. 4(A) is a perspective view showing a typical example of use of the measuring jig shown in FIG. 3(A), and FIG. 4(B) is a top view showing a typical example of use of the measuring jig shown in FIG. 3(A). [Diagram 5] FIG. 5(A) is a perspective view showing a typical example of use of the measuring jig shown in FIG. 3(B), and FIG. 5(B) is a top view showing a typical example of use of the measuring jig shown in FIG. 3(B). DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0022] An embodiment of the present invention will be described with reference to the accompanying drawings. FIG. 1 is a perspective view showing an example of a measuring jig. The measuring jig 2 shown in FIG. 1 has a rectangular parallelepiped main body 4. The main body 4 has a rectangular upper surface 4a and a lower surface, rectangular left side and right side 4b between the long side of the upper surface 4a and the long side of the lower surface, and rectangular front and rear surfaces between the short side of the upper surface 4a and the short side of the lower surface. Each of the long side of the upper surface 4a and the long side of the lower surface of the main body 4 is designed to be approximately equal to the width of a groove 14c formed in a chuck table 14 described later.

[0023] Furthermore, L-shaped first engagement parts 6, 8 are provided at the front end of each of the left and right side surfaces 4b of the main body 4. The first engagement parts 6, 8 have rectangular parallelepiped standing parts 6a, 8a whose lower parts are fixed to the main body 4 and whose upper parts are located higher than the upper surface 4a, and rectangular parallelepiped horizontal parts 6b, 8b that extend forward from the upper parts of the standing parts 6a, 8a. The lower surfaces of the horizontal parts 6b, 8b are located at approximately the same height as the upper surface 4a of the main body 4.

[0024] Similarly, L-shaped second engagement parts 10, 12 are provided at the rear end of each of the left and right side surfaces 4b of the main body 4. The second engagement parts 10, 12 have rectangular parallelepiped standing parts 10a, 12a whose lower parts are fixed to the main body 4 and whose upper parts are located higher than the upper surface 4a, and rectangular parallelepiped horizontal parts 10b, 12b that extend rearward from the upper parts of the standing parts 10a, 12a. The lower surfaces of the horizontal parts 6b, 8b are located at approximately the same height as the upper surface 4a of the main body 4.

[0025] The first engagement parts 6, 8 and the second engagement parts 10, 12 are connected by the main body part 4. The measurement jig 2 may be configured by combining the main body part 4, the first engagement parts 6, 8 and the second engagement parts 10, 12, which are independent structures, or may be a single structure in which the main body part 4, the first engagement parts 6, 8 and the second engagement parts 10, 12 are integrated. For example, the measurement jig 2 is a single structure manufactured by supplying a heated and softened thermoplastic resin to a specified mold and cooling it.

[0026] Fig. 2(A) is a perspective view that typically shows an example of use of the measuring jig 2, and Fig. 2(B) is a top view that typically shows an example of use of the measuring jig 2. The measuring jig 2 is used by being placed on, for example, a self-ground chuck table 14. This chuck table 14 has a disk-shaped frame 16 that is made of, for example, ceramics or the like.

[0027] The frame 16 has a disk-shaped bottom plate 16a. A cylindrical side wall 16b extending upward is provided on the outer edge of the upper surface of the bottom plate 16a. A cylindrical holder 16c extending upward is provided in the center of the upper surface of the bottom plate 16a. A disk-shaped recess is formed on the upper surface of the holder 16c, and a disk-shaped porous plate 18 made of ceramics or the like is fixed in this recess.

[0028] The chuck table 14 is used, for example, when grinding a workpiece of a work unit obtained by integrating a ring frame and a workpiece positioned in the opening of the ring frame with tape. Specifically, when grinding a workpiece in this manner, the upper surface of the holding portion 16c becomes the holding surface 14a of the chuck table that holds the workpiece via the tape, and the upper surface of the side wall 16b becomes the reference surface 14b with which one of the measuring probes of a pair of dial gauges comes into contact to measure the thickness of the workpiece.

[0029] Furthermore, when grinding the workpiece in this manner, the space defined by the bottom plate 16a, the sidewall 16b, and the holding portion 16c and open at the top becomes the groove 14c in which the ring frame is placed. That is, this grinding is performed in a state where the ring frame is placed inside the groove 14c, which has an inner side extending downward from the outer edge of the upper surface (holding surface 14a) of the holding portion 16c, an outer side extending downward from the inner edge of the upper surface (reference surface 14b) of the sidewall 16b, and a bottom surface extending from the lower end of the inner side to the lower end of the outer side.

[0030] The measuring jig 2 is used to measure the change in height of a measurement line 20 (see FIG. 2(B)) on the holding surface 14a and the reference surface 14b of the chuck table 14 using a dial gauge. The measurement line 20 is a curved area that overlaps with the rotation trajectory of multiple grinding wheels that perform self-grinding of the chuck table 14.

[0031] When carrying out this measurement, first, the measuring jig 2 is positioned so that the first engagement portions 6, 8 engage with the outer edge portion of the holding surface 14a of the chuck table 14 and the upper end portion of the inner surface of the groove 14c, and the second engagement portions 10, 12 engage with the inner edge portion of the reference surface 14b of the chuck table 14 and the upper end portion of the outer surface of the groove 14c. In addition, at this time, the measuring jig 2 is positioned so that the line to be measured 20 overlaps with the main body portion 4.

[0032] As a result, the holding surface 14a and the reference surface 14b are continuously connected via the upper surface 4a of the main body 4 at the measured line 20. Therefore, by using the measuring jig 2, it becomes possible to easily measure the change in height of the holding surface 14a and the reference surface 14b of the chuck table 14 at the measured line 20 using this dial gauge without dropping the probe of the dial gauge into the groove 14c formed in the chuck table 14.

[0033] The measuring jig of the present invention is not limited to the above-mentioned measuring jig 2. Fig. 3(A) and Fig. 3(B) are each a perspective view showing a schematic diagram of another example of the measuring jig of the present invention. Fig. 3(B) shows an enlarged view of a part of the upper surface of the measuring jig.

[0034] The measuring jig 22 shown in Fig. 3(A) has a first bridge portion 24, a second bridge portion 26, and a connecting portion 28 that connects the first bridge portion 24 and the second bridge portion 26. Here, the structures of the first bridge portion 24 and the second bridge portion 26 are similar to those of the measuring jig 2 shown in Fig. 1 and Figs. 2(A) and 2(B). Therefore, a description of the structures of the first bridge portion 24 and the second bridge portion 26 will be omitted here.

[0035] The connecting portion 28 is a plate-like structure curved in an arc, with the upper surface side of one end portion fixed to the lower surface side of the main body portion 24a of the first bridge portion 24, and the upper surface side of the other end portion fixed to the lower surface side of the main body portion 26a of the second bridge portion 26. The curvature of the connecting portion 28 is designed to be approximately equal to the curvature of the groove 14c formed in the chuck table 14 described above.

[0036] The measuring jig 22 may be configured by combining the first bridge section 24, the second bridge section 26, and the connecting section 28, which are independent structures, or may be a single structure in which the first bridge section 24, the second bridge section 26, and the connecting section 28 are integrated. For example, the measuring jig 22 is a single structure manufactured by supplying heated and softened thermoplastic resin to a specified mold and cooling it.

[0037] Fig. 4(A) is a perspective view that typically shows an example of use of the measuring jig 22, and Fig. 4(B) is a top view that typically shows an example of use of the measuring jig 22. The measuring jig 22 is used, for example, by being placed on the chuck table 14 that has been subjected to the above-mentioned self-grinding.

[0038] Specifically, the measuring jig 22 is used when measuring the change in height of a measurement line 30 on the holding surface 14a and the reference surface 14b of the chuck table 14 using a dial gauge. The measurement line 30 is a curved area that overlaps with the rotation trajectory of a plurality of grinding wheels that perform self-grinding of the chuck table 14.

[0039] When carrying out this measurement, first, the first bridge portion 24 and the second bridge portion 26 are each placed on the chuck table 14 in the same manner as when the above-mentioned measuring jig 2 is placed on the chuck table 14. At this time, the connecting portion 28 of the measuring jig 22 is positioned inside the groove 14c formed in the chuck table 14.

[0040] By using the measuring jig 22 in this manner, it becomes possible to easily measure the change in height of the measuring line 30 of the holding surface 14a and the reference surface 14b of the chuck table 14 using the dial gauge without dropping the probe of the dial gauge into the groove 14c formed in the chuck table 14. Note that the connecting portion 28 is positioned inside the groove 14c and does not interfere with this measurement.

[0041] The measuring jig 32 shown in Fig. 3(B) has a first bridge portion 34, a second bridge portion 36, and a connecting portion 38 that connects the first bridge portion 34 and the second bridge portion 36. Here, the structures of the first bridge portion 34 and the second bridge portion 36 are similar to those of the measuring jig 2 shown in Fig. 1 and Figs. 2(A) and 2(B). Therefore, a description of the structures of the first bridge portion 34 and the second bridge portion 36 will be omitted here.

[0042] The connecting portion 38 is a plate-like structure curved in an arc, with one end face side of the connecting portion 38 fixed to the front side of the first engagement portion 34a of the first bridge portion 34, and the other end face side of the connecting portion 38 fixed to the front side of the first engagement portion 36a of the second bridge portion 36. The curvature of the connecting portion 38 is designed to be approximately equal to the curvature of the measured line 30 described above. The lower surface of the connecting portion 38 is located at approximately the same height as the lower surfaces of the first engagement portions 34a, 36a.

[0043] Furthermore, projections and recesses 40 that function as scales are formed on the upper surface of the connecting portion 38. The projections and recesses include a plurality of linear grooves 40a that are generally parallel to one another. Each of the linear grooves 40a is formed so as to be positioned toward the center of the holding surface 14a of the chuck table 14 when the measuring jig 32 is placed on the chuck table 14.

[0044] The linear grooves 40a are classified into two types according to their length. Specifically, the linear grooves 40a that are approximately 2.5×n mm (n is a natural number excluding multiples of 5) away from the center of the connecting portion 38 are shorter than the other grooves. In addition, grooves 40b having shapes corresponding to the numbers indicating the distances from the center of the connecting portion 38 are formed near the linear grooves 40a. These grooves 40a, 40b are formed, for example, by applying laser marking to the upper surface side of the connecting portion 38 of the measuring jig 32.

[0045] The measuring jig 32 may be configured by combining the first bridge section 34, the second bridge section 36, and the connecting section 38, which are independent structures, or may be a single structure in which the first bridge section 34, the second bridge section 36, and the connecting section 38 are integrated. For example, the measuring jig 32 is a single structure manufactured by supplying heated and softened thermoplastic resin to a specified mold and cooling it, and then forming irregularities 40 on the upper surface of the connecting section 38 by laser marking.

[0046] Fig. 5(A) is a perspective view showing a typical example of use of the measuring jig 32, and Fig. 5(B) is a top view showing a typical example of use of the measuring jig 22. The measuring jig 32 is used, for example, by being placed on the chuck table 14 that has been subjected to the above-mentioned self-grinding. Specifically, the measuring jig 32 is used when measuring the change in height of the measuring line 30 on the holding surface 14a and the reference surface 14b of the chuck table 14 by means of a dial gauge.

[0047] When carrying out this measurement, first, the first bridge portion 34 and the second bridge portion 36 are each placed on the chuck table 14 in the same manner as when the above-mentioned measuring jig 2 is placed on the chuck table 14. At this time, the connecting portion 38 of the measuring jig 32 is placed so that the unevenness 40 is displayed along the line 30 to be measured.

[0048] By using the measuring jig 32 in this manner, it becomes possible to easily measure the change in height of the measuring line 30 of the holding surface 14a and the reference surface 14b of the chuck table 14 using the dial gauge without dropping the probe of the dial gauge into the groove 14c formed in the chuck table 14. Furthermore, in this case, by referring to the unevenness 40, it becomes easy to grasp the relationship between the distance from the center of the holding surface 14a and the height.

[0049] In the measuring jig 32, if the upper surface of the connecting portion 38 can function as a scale, the linear grooves 40a and the grooves 40b having shapes corresponding to the numbers do not have to be formed. For example, in the measuring jig 32, linear convex portions and convex portions having shapes corresponding to the numbers may be formed on the upper surface of the connecting portion 38 to function as a scale. In the measuring jig 32, the linear regions and the regions having shapes corresponding to the numbers on the upper surface of the connecting portion 38 may be colored to function as a scale.

[0050] In addition, the structures and methods according to the above-described embodiments can be modified as appropriate without departing from the scope of the present invention. [Explanation of symbols]

[0051] 2: Measuring tool 4: Main body (4a: top, 4b: right side, 4c: front) 6,8: First engaging part (6a, 8a: upright part, 6b, 8b: horizontal part) 10,12: Second engaging part (10a, 12a: upright part, 10b, 12b: horizontal part) 16: chuck table (16a: bottom plate, 16b: side wall, 16c: holding portion) 18:Porous plate 20: Line to be measured 22: Measuring tool 24: First bridge section (24a: Main body section) 26: 2nd bridge part (26a: main body part) 28:Connection part 30: Line to be measured 32: Measuring tool 34: 1st bridge part (34a: 1st engagement part) 36: 2nd bridge part (36a: 1st engagement part) 38:Connection part 40: Concave and convex (40a: Linear groove, 40b: Groove having a shape corresponding to a number)

Claims

1. a holding surface for holding the workpiece of a work unit obtained by integrating a ring frame and a workpiece positioned in an opening of the ring frame with a tape via the tape; a reference surface that is positioned outside the ring frame when the workpiece is held on the holding surface via the tape; a groove having an inner surface extending downward from an outer edge of the holding surface, an outer surface extending downward from an inner edge of the reference surface, and a bottom surface extending from a lower end of the inner surface to a lower end of the outer surface, the groove into which the ring frame is positioned when the workpiece is held on the holding surface via the tape; A measuring tool used when measuring a change in height of a measurement line between the holding surface of a chuck table and a reference surface by using a dial gauge, a first engagement portion for engaging an outer edge portion of the holding surface and an upper end portion of the inner surface; a second engagement portion for engaging an inner edge portion of the reference surface and an upper end portion of the outer surface; a main body portion connecting the first engagement portion and the second engagement portion, A measurement jig characterized in that when the first engagement portion engages with the outer edge of the holding surface and the upper end of the inner surface, and when the second engagement portion engages with the inner edge of the reference surface and the upper end of the outer surface, the main body portion continuously connects the holding surface and the reference surface.

2. a holding surface for holding the workpiece of a work unit obtained by integrating a ring frame and a workpiece positioned in an opening of the ring frame with a tape via the tape; a reference surface that is positioned outside the ring frame when the workpiece is held on the holding surface via the tape; a groove having an inner surface extending downward from an outer edge of the holding surface, an outer surface extending downward from an inner edge of the reference surface, and a bottom surface extending from a lower end of the inner surface to a lower end of the outer surface, the groove into which the ring frame is positioned when the workpiece is held on the holding surface via the tape; A measuring tool used when measuring a change in height of a measurement line between the holding surface of a chuck table and a reference surface by using a dial gauge, A first bridge portion, a second bridge portion, and a connecting portion that connects the first bridge portion and the second bridge portion, Each of the first bridge portion and the second bridge portion is a first engagement portion for engaging an outer edge portion of the holding surface and an upper end portion of the inner surface; a second engagement portion for engaging an inner edge portion of the reference surface and an upper end portion of the outer surface; a main body portion connecting the first engagement portion and the second engagement portion, a measuring jig characterized in that, when the first engagement portion of each of the first bridge portion and the second bridge portion engages with the outer edge portion of the holding surface and the upper end portion of the inner side surface, and the second engagement portion engages with the inner edge portion of the reference surface and the upper end portion of the outer side surface, the main body portion of each of the first bridge portion and the second bridge portion continuously connects the holding surface and the reference surface, and the connecting portion is positioned inside the groove.

3. a holding surface for holding the workpiece of a work unit obtained by integrating a ring frame and a workpiece positioned in an opening of the ring frame with a tape via the tape; a reference surface that is positioned outside the ring frame when the workpiece is held on the holding surface via the tape; a groove having an inner surface extending downward from an outer edge of the holding surface, an outer surface extending downward from an inner edge of the reference surface, and a bottom surface extending from a lower end of the inner surface to a lower end of the outer surface, the groove into which the ring frame is positioned when the workpiece is held on the holding surface via the tape; A measuring tool used when measuring a change in height of a measurement line between the holding surface of a chuck table and a reference surface by using a dial gauge, A bridge structure comprising: a first bridge portion; a second bridge portion; and a connecting portion that connects the first bridge portion and the second bridge portion and has a scale formed thereon; Each of the first bridge portion and the second bridge portion is a first engagement portion for engaging an outer edge portion of the holding surface and an upper end portion of the inner surface; a second engagement portion for engaging an inner edge portion of the reference surface and an upper end portion of the outer surface; a main body portion connecting the first engagement portion and the second engagement portion, a measuring jig characterized in that, when the first engagement portion of each of the first bridge portion and the second bridge portion engages with the outer edge portion of the holding surface and the upper end portion of the inner side surface, and the second engagement portion engages with the inner edge portion of the reference surface and the upper end portion of the outer side surface, the main body portion of each of the first bridge portion and the second bridge portion continuously connects the holding surface and the reference surface, and the connecting portion is positioned so that the scale is displayed along the measured line.

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