Dressing board and dressing method

Abstract

To prevent roughening of a ground surface of a wafer ground by a grindstone immediately after dressing.SOLUTION: In a dressing board 200, a dressing grindstone 205 is arranged outside shaping workpiece 203. Thereby, the dressing step brings the lower surface of each grindstone 77 into contact with the dressing grindstone 205 and the shaping workpiece 203 in this order. Therefore, new abrasive grains are made to project to the lower surfaces of the grindstones 77 by contact with the dressing grindstone 205, then the lower surfaces of the grindstones 77 are brought into contact with the shaping workpiece 203, and thereby the tip shapes of the newly projected abrasive grains can be shaped. For this reason, the lower surfaces of the grindstones 77 after the dressing step can be made good. Thereby, the wafer can be satisfactorily ground by the grindstones 77 immediately after the dressing while suppressing roughening of its ground surface.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a dressing board and a dressing method. [Background technology]

[0002] In a grinding process for grinding a product wafer such as a semiconductor wafer to a desired thickness, a grinding wheel with grinding stones arranged in a ring is rotated and the grinding stones are brought into contact with the product wafer to perform grinding. If the product wafer is made of a hard material, the abrasive grains exposed on the grinding surface of the grinding stone are worn away, and the grinding ability of the grinding stone is reduced. On the other hand, if the product wafer is made of a soft material, the grinding debris is clogged on the grinding surface of the grinding stone, preventing the exposure of the abrasive grains and the self-sharpening of the edge, and the grinding ability of the grinding stone is reduced.

[0003] Therefore, there is a technique for periodically grinding the dressing board with a grinding wheel to expose new abrasive grains on the grinding surface of the grinding wheel and restore the grinding ability of the grinding surface. Such dressing boards are made of green carbonite (GC) or white alundum (WA) abrasive grains bound with a bonding agent and molded into a specified shape (see, for example, Patent Document 1). [Prior art documents] [Patent documents]

[0004] [Patent Document 1] JP 2014-217935 A [Patent Document 2] JP 2019-141949 A Summary of the Invention [Problem to be solved by the invention]

[0005] When using a conventional dressing board as described in Patent Document 1, the grinding surface of the product wafer may become rough when the product wafer is ground with a grinding wheel immediately after dressing. Therefore, in order to suppress the roughness of the grinding surface of the product wafer, it is necessary to smooth the tip shape of the abrasive grains protruding from the grinding surface by grinding an object to be ground that is not a product wafer (such as a dummy wafer) with the grinding wheel immediately after dressing. However, this is a factor that reduces the throughput in wafer grinding.

[0006] Therefore, in order to prevent the ground surface from becoming rough when the product wafer is ground with a grinding wheel immediately after dressing using a dressing board, the dressing board disclosed in Patent Document 2 has a dressing wheel placed in the center and a ring-shaped workpiece made of the same material as the wafer placed on the outside of the dressing wheel.

[0007] However, in in-feed grinding, the lower surface of the grinding wheel is brought into contact with the radius of the dressing board in an arc shape, and grinding is performed from the outer periphery of the dressing board toward the center. Therefore, in in-feed grinding, the grinding wheel leaves the dressing board immediately after grinding the central dressing wheel. Therefore, the ground surface of the product wafer becomes rough, especially when the grinding amount of the product wafer is small.

[0008] Therefore, an object of the present invention is to suppress roughening of the ground surface of a product wafer when the product wafer is ground with a grinding wheel immediately after dressing. [Means for solving the problem]

[0009] The dressing board of the present invention (the present dressing board) is a dressing board for dressing the underside of grinding stones arranged in a ring shape on a grinding wheel, and comprises a circular base, a shaping workpiece arranged in the center of the base and made of the same material as the workpiece to be ground after dressing of the grinding stones, and a dressing stone arranged outside the shaping workpiece on the base and containing abrasive grains fixed with a bonding agent, and the upper surface of the shaping workpiece and the upper surface of the dressing stone are formed so as to be flush with each other.

[0010] In this dressing board, the workpiece to be shaped and the dressing grindstone may be arranged on the base so that a gap is formed.

[0011] The dressing method of the present invention is a dressing method for dressing the underside of the grinding wheel using the dressing board, and includes a holding step of holding the dressing board via the base by the holding surface of a chuck table, a thickness calculation step of measuring the height of the upper surface of the workpiece to be shaped of the dressing board held in the holding step and the height of the holding surface and calculating the thickness of the dressing board, and a grinding mechanism equipped with the grinding wheel is lowered to dress the underside of the grinding wheel of the dressing board and the workpiece to be shaped. The method includes a dressing process in which the underside of the grinding wheel is sharpened by contacting the underside of the grinding wheel with a dressing board; a post-dressing thickness calculation process in which the thickness of the dressing board after the dressing process is calculated; and a setup process in which the height position of the grinding mechanism lowered by the thickness of the dressing board calculated in the post-dressing thickness calculation process from the height position of the grinding mechanism at the end of the dressing process is stored as the origin height position of the grinding mechanism at which the underside of the grinding wheel contacts the holding surface. Effect of the Invention

[0012] In this dressing board, the dressing wheel is disposed outside the workpiece to be shaped. As a result, in dressing the grinding wheel using this dressing board, the lower surface of each grinding wheel contacts the dressing wheel and the workpiece to be shaped in that order, and then separates from the dressing board. Therefore, after new abrasive grains are protruded from the lower surface of the grinding wheel by contacting the dressing wheel, the lower surface of the grinding wheel can be brought into contact with the workpiece to be shaped to adjust the tip shape of the newly protruded abrasive grains. Therefore, the lower surface of the grinding wheel after the dressing process can be kept in a good condition. As a result, the grinding wheel immediately after dressing can grind the workpiece well while suppressing roughening of the grinding surface. [Brief description of the drawings]

[0013] [Figure 1] FIG. 2 is a perspective view showing a configuration of a grinding device. [Diagram 2] An oblique view showing the configuration of a dressing board. [Diagram 3] 11A to 11C are side cross-sectional views showing a holding step and a thickness calculation step. [Figure 4] 11 is a side cross-sectional view showing a dressing step, a post-dressing thickness calculation step, and a setup step. FIG. [Diagram 5] FIG. [Figure 6] An oblique view showing another configuration of the dressing board. [Figure 7] An oblique view showing another configuration of the dressing board. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] As shown in Fig. 1, the grinding apparatus 1 according to this embodiment is an apparatus for grinding a wafer 100 as a workpiece (product wafer). The wafer 100 is, for example, a semiconductor wafer. A front surface 101 of the wafer 100 facing downward in Fig. 1 holds a plurality of devices and is protected by the attachment of a protective tape 103. A back surface 102 of the wafer 100 is the grinding surface on which the grinding process is performed.

[0015] The grinding device 1 includes a rectangular parallelepiped base 10 and a column 11 extending upward.

[0016] An opening 13 is provided on the upper surface side of the base 10. In the opening 13, a chuck table 20 is disposed.

[0017] The chuck table 20 has a substantially disk-shaped frame 23, and has a holding portion 21 made of a porous material in a recess provided in the frame 23. The upper surface of the holding portion 21 serves as a holding surface 22 that suction-holds the wafer 100. The holding surface 22 is connected to a suction source (not shown) to suction-hold the wafer 100. That is, the chuck table 20 holds the wafer 100 by means of the holding surface 22. In addition, a frame surface 24, which is the upper surface of the frame 23, is formed to be flush with the holding surface 22.

[0018] The chuck table 20 can also hold a dressing board 200 shown in Fig. 2. The dressing board 200 is used for dressing the grinding wheel 77 of the grinding mechanism 70.

[0019] Further, a driving member 25 that rotates and drives the chuck table 20 is provided below the chuck table 20. This driving member 25 allows the chuck table 20 to rotate about a rotation axis that passes through the center of the holding surface 22 and extends in the Z-axis direction while the wafer 100 or the dressing board 200 is held by the holding surface 22. Therefore, the wafer 100 or the dressing board 200 is held by the holding surface 22 and rotated about the center of the holding surface 22 as the rotation axis.

[0020] Further, a tilt adjustment mechanism 26 is provided on the chuck table 20 via a coupling or the like. The tilt adjustment mechanism 26 can adjust the tilt of the holding surface 22 of the chuck table 20 with respect to the horizontal plane (the tilt of the grinding wheel 77 with respect to the grinding surface).

[0021] A cover plate 27 that moves along the Y-axis direction together with the chuck table 20 is provided around the chuck table 20. A bellows cover 12 that expands and contracts in the Y-axis direction is connected to the cover plate 27. A table movement mechanism (not shown) is provided below the chuck table 20. The table movement mechanism moves the chuck table 20 along the Y-axis direction.

[0022] In this embodiment, the chuck table 20 is moved along the Y-axis direction by a Y-axis moving mechanism between a holding position on the -Y direction side for holding the wafer 100 or dressing board 200 on the holding surface 22 and a grinding position on the +Y direction side where the wafer 100 or dressing board 200 is ground.

[0023] 1, a column 11 is provided upright on the +Y direction side of the base 10. The column 11 is provided with a grinding mechanism 70 for grinding the wafer 100, and a grinding feed mechanism 30.

[0024] The grinding feed mechanism 30 is configured to move the grinding mechanism 70 in the Z-axis direction relative to the chuck table 20.

[0025] The grinding feed mechanism 30 includes a pair of Z-axis guide rails 31 parallel to the Z-axis direction, a Z-axis moving table 33 that slides on the Z-axis guide rails 31, a Z-axis ball screw 32 parallel to the Z-axis guide rails 31, a Z-axis motor 34, and a holder 36 attached to the Z-axis moving table 33. The holder 36 supports the grinding mechanism 70.

[0026] The Z-axis moving table 33 is slidably installed on the Z-axis guide rail 31. A nut portion (not shown) is fixed to the Z-axis moving table 33. The Z-axis ball screw 32 is screwed into the nut portion. The Z-axis motor 34 is connected to one end of the Z-axis ball screw 32.

[0027] In the grinding feed mechanism 30, the Z-axis motor 34 rotates the Z-axis ball screw 32, thereby moving the Z-axis moving table 33 in the Z-axis direction along the Z-axis guide rail 31. As a result, the holder 36 attached to the Z-axis moving table 33 and the grinding mechanism 70 supported by the holder 36 move in the Z-axis direction together with the Z-axis moving table 33.

[0028] The grinding mechanism 70 grinds the wafer 100 held by suction on the holding surface 22. The grinding mechanism 70 includes a spindle housing 71 fixed to the holder 36, a spindle 72 rotatably held by the spindle housing 71, a spindle motor 73 that rotates the spindle 72, a wheel mount 74 attached to the lower end of the spindle 72, and a grinding wheel 75 supported by the wheel mount 74.

[0029] The spindle housing 71 is held by the holder 36 so as to extend in the Z-axis direction. The spindle 72 extends in the Z-axis direction so as to be perpendicular to the holding surface 22 of the chuck table 20, and is supported by the spindle housing 71 so as to be rotatable.

[0030] The spindle motor 73 is connected to the upper end side of the spindle 72. The spindle motor 73 rotates the spindle 72 about a rotation axis extending in the Z-axis direction.

[0031] The wheel mount 74 is formed in a disk shape, and is fixed to the lower end (tip) of the spindle 72. The wheel mount 74 supports the grinding wheel 75.

[0032] The grinding wheel 75 is formed to have an outer diameter approximately equal to the outer diameter of the wheel mount 74. The grinding wheel 75 includes a wheel base 76 formed from a metal material. A plurality of grinding wheels 77 arranged in a ring shape are fixed to the lower surface of the wheel base 76 over the entire circumference. The grinding wheels 77 are rotated by the spindle motor 73 together with the spindle 72, and grind the back surface 102 of the wafer 100 held on the chuck table 20 with their grinding surface (lower surface).

[0033] In this manner, the grinding mechanism 70 is configured to rotate annular grinding wheel 77 attached to a wheel mount 74 disposed at the tip of the spindle 72, and to abut the underside of the grinding wheel 77 against the wafer 100 held on the holding surface 22 of the chuck table 20, thereby grinding the wafer 100.

[0034] In addition, the grinding mechanism 70 can also grind the dressing board 200 held on the chuck table 20, in the same way as the wafer 100.

[0035] A thickness gauge 55 is disposed at a position adjacent to the chuck table 20 on the base 10. The thickness gauge 55 can measure the thickness of the wafer 100 during grinding, for example, by contact. That is, the thickness gauge 55 has a first contactor 56 for contacting the frame surface 24, which is flush with the holding surface 22 of the chuck table 20, to measure the height, a second contactor 57 for contacting the wafer 100 to measure the height, and a thickness calculation unit 58.

[0036] In the thickness measuring device 55, the height of the holding surface 22 of the chuck table 20 and the height of the wafer 100 are obtained by the first contactor 56 and the second contactor 57. Thereafter, a thickness calculation unit 58 measures the thickness of the wafer 100 based on the difference between these heights. Note that the thickness measuring device 55 can also measure the thickness of the dressing board 200 held on the chuck table 20, similar to the wafer 100.

[0037] Further, a linear scale 51 for measuring the height position of the grinding mechanism 70 is disposed on the column 11. The linear scale 51 includes a reading unit 52 that is provided on the Z-axis moving table 33 and moves in the Z-axis direction together with the Z-axis moving table 33, and a scale unit 53 that is provided on the surface of the Z-axis guide rail 31. The reading unit 52 reads the scale of the scale unit 53, thereby measuring the height position of the grinding mechanism 70.

[0038] The grinding apparatus 1 also includes a control unit 7 that controls each component of the grinding apparatus 1. The control unit 7 includes a CPU that performs calculation processing according to a program, and a storage medium such as a memory. The control unit 7 controls each component of the grinding apparatus 1 described above to perform grinding processing on the wafer 100. Furthermore, the control unit 7 performs dressing of the grinding wheel 77 by using a dressing board 200 shown in FIG.

[0039] Here, the configuration of the dressing board 200 will be described. 2 is used to dress the underside of the grinding stone 77 arranged in a ring shape on the grinding wheel 75 of the grinding mechanism 70. The dressing board 200 has a disk-shaped base 201, a disk-shaped workpiece 203 arranged on the surface of the base 201, and a ring-shaped dressing stone 205.

[0040] The shaped workpiece 203 is placed at the center of the base 201, and is made of the same material as the wafer 100, which is the workpiece to be ground after dressing by the grinding wheel 77. The dressing wheel 205 is placed outside the shaped workpiece 203 on the base 201, and contains abrasive grains fixed with a bonding agent. In this embodiment, the dressing wheel 205 is formed in a ring shape surrounding the shaped workpiece 203.

[0041] The upper surface of the workpiece 203 to be shaped and the upper surface of the dress grindstone 205 are formed so as to be flush with each other (to have the same height).

[0042] The workpiece 203 to be shaped and the dress grindstone 205 are arranged on the base 201 so as to form a gap, i.e., so as to generate an area on the base 201 where neither the workpiece 203 to be shaped nor the dress grindstone 205 is arranged. In this embodiment, as shown in FIG. 2, a ring-shaped gap 207 is formed between the disk-shaped workpiece 203 to be shaped and the ring-shaped dress grindstone 205.

[0043] Next, a dressing method for dressing the lower surface of the grinding wheel 77 using the dressing board 200 having such a configuration will be described.

[0044] [Holding process] First, a holding step is performed. In this step, the holding surface 22 of the chuck table 20 shown in FIG.

[0045] Specifically, the control unit 7 uses a table moving mechanism (not shown) to place the chuck table 20 at a predetermined holding position on the -Y direction side away from below the grinding mechanism 70. Next, the control unit 7 or an operator places the dressing board 200 on the holding surface 22 of the chuck table 20 via the base 201 so that the shaped workpiece 203 and the dress grindstone 205 face upward. Thereafter, the control unit 7 connects the holding surface 22 to a suction source. As a result, the dressing board 200 is suction-held by the holding surface 22 as shown in FIG. 3.

[0046] [Thickness calculation process] Following the holding step, a thickness calculation step is carried out. In this step, the height of the top surface of the workpiece 203 on the dressing board 200 held in the holding step and the height of the holding surface 22 of the chuck table 20 are measured, and the thickness of the dressing board is calculated.

[0047] Specifically, the control unit 7 first uses the table moving mechanism to place the chuck table 20 at a grinding position below the grinding mechanism 70. Then, as shown in FIG. 3, the control unit 7 brings the first contactor 56 of the thickness measuring device 55 into contact with the frame surface 24 that is flush with the holding surface 22 on the chuck table 20 to measure the height of the holding surface 22. Furthermore, the control unit 7 brings the second contactor 57 of the thickness measuring device 55 into contact with the upper surface of the workpiece 203 on the dressing board 200 to measure the upper surface height of the workpiece 203. Then, the thickness calculation unit 58 calculates the thickness of the dressing board 200 based on the difference between the measured height of the holding surface 22 and the upper surface height of the workpiece 203. In addition, an operator may measure the thickness of the dressing board 200 using a thickness gauge or the like, and input the value into the grinding apparatus 1 via an input unit (not shown), thereby storing the value in the control unit 7 of the grinding apparatus 1.

[0048] [Dressing process] After the thickness calculation process, a dressing process is performed. In this process, the grinding mechanism 70 equipped with the grinding wheel 77 is lowered, and the lower surface of the grinding wheel 77 is brought into contact with the dressing wheel 205 of the dressing board 200 and the workpiece 203 to be shaped, thereby dressing the lower surface of the grinding wheel 77.

[0049] Specifically, as shown in FIG. 4, the control unit 7 rotates the chuck table 20, which holds the dressing board 200 by suction, at a speed of, for example, 40 to 300 min-1 using the driving member 25 as shown by arrow 301, and also rotates the spindle 72 in the grinding mechanism 70 at a speed of, for example, 1000 to 3000 min-1 using the spindle motor 73, thereby rotating the grinding wheel 77 as shown by arrow 302.

[0050] In this state, the control unit 7 uses the grinding feed mechanism 30 to lower the grinding mechanism 70, for example at a relatively high initial speed, to position the lower surface of the grinding wheel 77 at a position higher than the holding surface 22 by the thickness of the dressing board 200 calculated in the thickness calculation process. Thereafter, the control unit 7 lowers the grinding mechanism 70 at a predetermined, relatively slow grinding speed, for example, using the grinding feed mechanism 30, and brings the grinding wheel 77 into contact with the workpiece 203 to be shaped and the dressing wheel 205 in the arc-shaped radial portion R1 of the dressing board 200 held on the chuck table 20, as shown in FIG. 5, and grinds (in-feed grinds) the workpiece 203 to be shaped and the dressing wheel 205 using the grinding wheel 77.

[0051] As a result, the underside of each grinding wheel 77 comes into contact with the dressing wheel 205 of the dressing board 200 and the workpiece 203 to be shaped in that order, and is sharpened by them. That is, new abrasive grains protrude from the underside of the grinding wheel 77 upon contact with the dressing wheel 205, and the tip shape of the newly protruding abrasive grains is adjusted by subsequent contact with the workpiece 203 to be shaped. The underside of the grinding wheel 77 then leaves the dressing board 200. In addition, grinding chips generated by grinding the dressing grindstone 205 with the grinding wheel 77 are discharged into a gap 207 between the shaped workpiece 203 and the dressing grindstone 205.

[0052] Furthermore, as shown in FIG. 4, at the end of the dressing process, the control unit 7 uses the linear scale 51 to measure the height position Z1 of the grinding mechanism 70 at the end of the dressing process, and stores it in a memory (not shown).

[0053] [Post-dressing thickness calculation process] After the dressing process, a post-dressing thickness calculation process is carried out. In this process, the thickness of the dressing board 200 after the dressing process is calculated.

[0054] 4, the control unit 7 brings the first contactor 56 of the thickness measuring device 55 into contact with the frame surface 24 of the chuck table 20 to measure the height of the holding surface 22, and brings the second contactor 57 into contact with the upper surface of the workpiece 203 to be shaped on the dressing board 200 to measure the upper surface height of the workpiece 203 to be shaped. Then, the thickness calculation unit 58 calculates the thickness of the dressing board 200 after dressing based on the difference between the height of the holding surface 22 and the upper surface height of the workpiece 203 to be shaped.

[0055] [Setup process] After the post-dressing thickness calculation process, a setup process is performed. In this process, the height position of the grinding mechanism 70 lowered by the thickness of the dressing board 200 calculated in the post-dressing thickness calculation process from the height position of the grinding mechanism 70 at the end of the dressing process is stored as the origin height position of the grinding mechanism 70 where the lower surface of the grinding wheel 77 contacts the holding surface 22.

[0056] Specifically, the control unit 7 reads out from the memory the height position Z1 (see FIG. 4) of the grinding mechanism 70 at the end of the dressing process, which is measured using the linear scale 51 at the end of the dressing process. Thereafter, the control unit 7 calculates the origin height position Z2 of the grinding mechanism 70 where the lower surface of the grinding wheel 77 contacts the holding surface 22 by subtracting the thickness T1 of the dressing board 200 after dressing, calculated in the post-dressing thickness calculation process, from this height position Z1, and stores it in the memory.

[0057] As described above, in the dressing board 200 according to the present embodiment, the dressing grindstone 205 is disposed outside the workpiece 203. As a result, in the dressing process in which the dressing board 200 is in-feed ground, the lower surface of each grinding wheel 77 contacts the dressing wheel 205 and the workpiece 203 in that order, and then separates from the dressing board 200. Therefore, after new abrasive grains are protruded from the lower surface of the grinding wheel 77 by contacting the dressing wheel 205, the lower surface of the grinding wheel 77 is brought into contact with the workpiece 203 to adjust the tip shape of the newly protruded abrasive grains. Therefore, the lower surface of the grinding wheel 77 after the dressing process can be kept in a good state. As a result, the wafer 100 can be well ground by the grinding wheel 77 immediately after dressing while suppressing roughening of the grinding surface.

[0058] In this embodiment, the setup process is performed after the dressing process to determine the origin height position Z2 of the grinding mechanism 70. This makes it possible to smoothly perform grinding of the wafer 100 immediately after the dressing process.

[0059] Moreover, in the dressing board 200 according to the present embodiment, the workpiece 203 to be shaped and the dressing wheel 205 are arranged on the base 201 so as to form a gap 207. This allows grinding chips generated by the grinding wheel 77 grinding the dressing wheel 205 to be efficiently discharged from the upper surface of the dressing wheel 205.

[0060] In the above-described embodiment, the dressing board 200 has a disk-shaped workpiece 203 to be shaped arranged at the center of the base 201, and a ring-shaped dressing grindstone 205 arranged on the base 201 so as to surround the workpiece 203 to be shaped. In this regard, for example, the dressing board 200 may be configured to have a disk-shaped workpiece 203 to be shaped arranged at the center of the base 201, and multiple (e.g., four) disk-shaped dressing grindstones 205 arranged at approximately equal intervals around the workpiece 203 to be shaped, as shown in FIG. 6.

[0061] In this configuration, four dressing grindstones 205 are scattered on the base 201 of the dressing board 200. Therefore, gaps 207 (open spaces in the base 201) in the base 201 are provided not only between the workpiece 203 to be shaped and the dressing grindstones 205, but also between the dressing grindstones 205 themselves. Therefore, grinding chips generated by the grinding wheel 77 grinding the dressing grindstone 205 can be more effectively discharged from the upper surface of the dressing grindstone 205.

[0062] 7, the dressing board 200 may be configured to have a rectangular (e.g., square) plate-shaped workpiece 203 arranged at the center of the base 201, and a plurality of (e.g., four) disk-shaped dressing wheels 205 arranged at approximately equal intervals around the workpiece 203. In this configuration, the corners of the workpiece 203 are arranged in the gaps between the dressing wheels 205. Even in this configuration, grinding chips can be effectively discharged from the upper surface of the dressing wheel 205. Furthermore, by making the workpiece 203 a rectangular plate, the grinding load on the grinding wheel 77 caused by the four dressing wheels 205 scattered therebetween can be made uniform.

[0063] In addition, during the dressing process, the control unit 7 may use a thickness measuring device 55 to measure the thickness of the dressing board 200 being ground, and may perform the dressing process, for example, until the thickness of the dressing board 200 reaches a predetermined thickness. [Explanation of symbols]

[0064] 1: grinding device, 7: control unit, 10: base, 11: column, 12: bellows cover, 13: opening, 20: chuck table, 21: holding portion, 22: holding surface, 23: frame body, 24: frame surface, 25: driving member, 26: tilt adjustment mechanism, 27: cover plate, 30: Grinding feed mechanism, 31: Z-axis guide rail, 32: Z-axis ball screw, 33: Z-axis moving table, 34: Z-axis motor, 36: holder, 51: linear scale, 52: reading unit, 53: scale unit, 55: thickness measuring device, 56: first contact, 57: second contactor, 58: thickness calculation unit, 70: grinding mechanism, 71: spindle housing, 72: spindle, 73: spindle motor, 74: wheel mount, 75: grinding wheel, 76: wheel base, 77: grinding stone, 100: wafer, 101: front surface, 102: back surface, 103: protective tape, 200: Dressing board, 201: Base, 203: Shaping workpiece, 205: Dressing wheel, 207: Gap, R1: Radius, T1: Thickness, Z1: Height position, Z2: Origin height position

Claims

1. A dressing board for dressing the underside of a grinding stone arranged in a ring shape on a grinding wheel, A disk-shaped base, A shaped workpiece is placed at the center of the base and is made of the same material as the workpiece to be ground after the grinding wheel is dressed; A dressing wheel is disposed on the base outside the workpiece and includes abrasive grains fixed with a bonding agent. The upper surface of the workpiece and the upper surface of the dressing grindstone are formed so as to be flush with each other. Dressing board.

2. The workpiece and the dressing grindstone are disposed on the base so that a gap is formed between them. A dressing board as described in claim 1.

3. A method for dressing the underside of the grinding wheel using the dressing board according to claim 1 or 2, comprising: a holding step of holding the dressing board via the base by a holding surface of a chuck table; a thickness calculation process for measuring the height of the upper surface of the workpiece of the dressing board held in the holding process and the height of the holding surface, and calculating the thickness of the dressing board; a dressing step of lowering a grinding mechanism equipped with the grinding wheel and bringing the lower surface of the grinding wheel into contact with the dressing wheel of the dressing board and the workpiece to be shaped, thereby dressing the lower surface of the grinding wheel; a post-dressing thickness calculation step of calculating a thickness of the dressing board after the dressing step; a setup process for storing a height position of the grinding mechanism lowered by the thickness of the dressing board calculated in the post-dressing thickness calculation process from the height position of the grinding mechanism at the end of the dressing process as an origin height position of the grinding mechanism where the lower surface of the grinding wheel contacts the holding surface; A dressing method comprising the steps of:

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