Adjustment method and grinding device

Abstract

To reduce a frequency of calibration work resulting from wear of a probe.SOLUTION: A grinding device includes: a chuck table; a grinding unit which grinds a workpiece held by the chuck table; a first height gauge which measures the height of the upper surface of the chuck table; a second height gauge which measures the height of the upper surface of the workpiece held by the chuck table; and a calculation part which calculates the thickness of the workpiece on the basis of the difference between heights of the upper surface of the chuck table measured by the first height guage and the upper surface of the workpiece measured by the second height guage. An adjustment method for adjusting the first height guage and the second height gauge in the grinding device includes: a holding step in which a dresser board is held by the chuck table; and a wear step in which the probe of the first height gauge and the probe of the second height guage are placed in contact with the dresser board to be worn.SELECTED DRAWING: Figure 5

Description

[Technical field]

[0001] The present invention relates to a grinding device equipped with a height gauge, which measures the height of the upper surface of a workpiece, in a grinding device equipped with a chuck table for holding the workpiece and a grinding unit for grinding the workpiece held by the chuck table, and to an adjustment method for adjusting a height gauge that measures the height of the upper surface of the workpiece, and to a grinding device equipped with a height gauge. [Background technology]

[0002] In the device chip manufacturing process, a disk-shaped wafer is processed on which devices such as ICs (Integrated Circuits) and LSIs (Large Scale Integrations) are formed in multiple areas partitioned by multiple intersecting division lines (streets). The wafer is thinned by grinding from the back side with a grinding device, and then divided along the division lines with a cutting device or laser processing device to manufacture individual device chips. Device chips are mounted on various electronic devices such as mobile phones and personal computers.

[0003] The grinding device includes a chuck table for holding a workpiece, a grinding unit for grinding the workpiece held by the chuck table, and a grinding feed unit for relatively feeding the chuck table and the grinding unit. The grinding unit includes a grinding wheel for contacting and grinding the workpiece.

[0004] The grinding device further includes a first height gauge for measuring the height of the upper surface of the chuck table, and a second height gauge for measuring the height of the upper surface of the workpiece to be ground by the grinding unit. The grinding device operates the two height gauges while grinding the upper surface of the workpiece held by the chuck table with a grinding wheel, and calculates the thickness of the workpiece from the difference between the measured values ​​of the two height gauges. In other words, the workpiece is ground while monitoring the thickness of the workpiece with the height gauges, and the workpiece is thinned to a predetermined thickness (see Patent Documents 1 to 3). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] JP 2008-73785 A [Patent Document 2] JP 2000-354962 A [Patent Document 3] Patent Publication No. 2022-40984 Summary of the Invention [Problem to be solved by the invention]

[0006] A height gauge has a probe that comes into contact with the top surface of the workpiece or the chuck table. The bottom surface of the probe becomes the contact surface that comes into contact with the top surface of the workpiece or other measurement target. Because the chuck table that supports the workpiece rotates while the workpiece is being ground, the probe that comes into contact with the top surface of the workpiece or other measurement target wears out from the contact surface side due to friction. For this reason, the probe of a height gauge is replaced periodically.

[0007] When the gauge head comes into contact with the top surface of the object to be measured, it is assumed that the bottom surface of the gauge head faces the top surface of the object to be measured. In other words, it is assumed that the bottom surface of the gauge head and the top surface of the object to be measured are parallel. However, when the gauge head is attached to the height gauge, a certain amount of error occurs in the orientation of the gauge head. In addition, there is also a certain amount of error in the orientation of the chuck table. Therefore, in the initial stage of using the gauge head, the corners and sharp parts of the bottom surface of the gauge head come into contact with the top surface of the workpiece, etc., and the gauge head is significantly worn out.

[0008] When the gauge head becomes significantly worn, measurements are no longer performed correctly, and the measurement accuracy of the height gauge decreases. For this reason, in conventional grinding machines, frequent calibration of the height gauge was required, especially immediately after replacing the gauge head. Since the grinding machine cannot grind the workpiece during the calibration of the height gauge, this also led to a decrease in the processing efficiency of the workpiece.

[0009] The present invention has been made in consideration of such problems, and an object of the present invention is to provide a height gauge adjustment method and a grinding apparatus that can reduce the frequency of calibration work caused by wear of the measuring element. [Means for solving the problem]

[0010] According to one aspect of the present invention, there is provided a grinding device including a chuck table for holding a workpiece, a grinding unit for grinding the workpiece held by the chuck table, a grinding feed unit for relatively grinding the grinding unit and the chuck table, a first height gauge for measuring the height of an upper surface of the chuck table, a second height gauge for measuring the height of the upper surface of the workpiece held by the chuck table, and a calculation unit for calculating a thickness of the workpiece based on a difference between the height of the upper surface of the chuck table measured by the first height gauge and the height of the upper surface of the workpiece measured by the second height gauge. The adjustment method includes a holding step for holding a dresser board with the chuck table, and a wearing step for bringing a measuring probe of the first height gauge and a measuring probe of the second height gauge into contact with the dresser board to wear them.

[0011] Preferably, the dresser board has a disk shape having a diameter larger than that of the workpiece.

[0012] According to another aspect of the present invention, there is provided a chuck table for holding a workpiece, a grinding unit for grinding the workpiece held by the chuck table, a grinding feed unit for relatively feeding the grinding unit and the chuck table, a first height gauge for measuring the height of an upper surface of the chuck table, a second height gauge for measuring the height of an upper surface of the workpiece held by the chuck table, and a height determination unit for determining a height of the upper surface of the chuck table based on a difference between the height of the upper surface of the chuck table measured by the first height gauge and the height of the upper surface of the workpiece measured by the second height gauge. and an adjustment unit that adjusts the first height gauge and the second height gauge, wherein when a dresser board is placed on the chuck table, the adjustment unit sucks and holds the dresser board on the chuck table, and rotates the chuck table around an axis intersecting the upper surface while bringing a measuring element of the first height gauge and a measuring element of the second height gauge into contact with the dresser board and wearing them, thereby adjusting the first height gauge and the second height gauge.

[0013] Preferably, the dresser board has a disk shape having a diameter larger than that of the workpiece. Effect of the Invention

[0014] In an adjustment method and a grinding device according to one aspect of the present invention, a dresser board is held by a chuck table, and a gauge head of a first height gauge and a gauge head of a second height gauge are brought into contact with the dresser board and worn. In this case, the shape of the bottom surface of the gauge head is worn to correspond to the shape of the upper surface of the dresser board. Therefore, even if there is an error in the orientation of the gauge head or the chuck table, the bottom surface of the gauge head after wearing is shaped to face the upper surface of the dresser board.

[0015] Thereafter, when the workpiece is held by the chuck table instead of the dresser board, the bottom surface of the gauge head of the first height gauge faces the top surface of the chuck table, and the bottom surface of the gauge head of the second height gauge faces the top surface of the workpiece. In other words, the bottom surface of the gauge head of the first height gauge becomes parallel to the top surface of the chuck table, and the bottom surface of the gauge head of the second height gauge becomes parallel to the top surface of the workpiece.

[0016] In this case, when grinding the workpiece, each of the gauge heads comes into contact with the workpiece over a wide area, resulting in a relatively small amount of wear. Therefore, the measurement accuracy of the height gauge is less likely to decrease, and there is no need to frequently calibrate the height gauge, even immediately after replacing the gauge head. Therefore, the decrease in the processing efficiency of the workpiece caused by the calibration of the height gauge can be minimized.

[0017] Therefore, one aspect of the present invention provides a height gauge adjustment method and a grinding device that can reduce the frequency of calibration work caused by wear of the gauge head. [Brief description of the drawings]

[0018] [Figure 1] FIG. 2 is a perspective view showing a grinding device. [Diagram 2] FIG. 2 is a perspective view showing a schematic view of a thickness measuring unit. [Diagram 3] FIG. 3(A) is a projection diagram that shows a model of a height gauge, and FIG. 3(B) is a projection diagram that shows a model of a part of the height gauge. [Figure 4] FIG. 2 is a cross-sectional view illustrating a chuck table and a dresser board. [Diagram 5] FIG. 11 is a cross-sectional view showing a schematic view of a state in which a probe is worn by a dresser board. [Figure 6] FIG. 4 is a cross-sectional view showing a schematic view of how the thickness of a workpiece is measured using a height gauge. [Figure 7] 4 is a flowchart showing the flow of each step of a height gauge adjustment method. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0019] Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the height gauge adjustment method according to this embodiment, a height gauge used in a grinding device is adjusted. First, a workpiece to be ground by the grinding device will be described. FIG. 1 includes a perspective view that typically shows the workpiece 1. FIG. 6 includes a cross-sectional view that typically shows a part of the workpiece 1.

[0020] The workpiece 1 is a disk-shaped wafer made of a material such as silicon, and has a front surface 1a and a back surface 1b that are parallel to each other. A plurality of planned division lines (not shown) are set on the front surface 1a of the workpiece 1, and are arranged in a lattice pattern so as to intersect with each other. Devices (not shown), such as ICs and LSIs, are formed in each of the regions partitioned by the planned division lines on the front surface 1a of the workpiece 1.

[0021] There are no limitations on the material, structure, size, shape, etc. of the workpiece 1. For example, the workpiece 1 may be a substrate made of a semiconductor other than silicon (GaAs, InP, GaN, SiC, etc.), sapphire, glass (quartz glass, borosilicate glass, etc.), etc. The workpiece 1 may also be a rectangular package substrate formed by arranging multiple device chips vertically and horizontally and sealing them with resin. There are also no limitations on the type, number, shape, structure, size, arrangement, etc. of the devices, and the workpiece 1 does not necessarily have to have any devices formed thereon.

[0022] When the workpiece 1 is ground from the back surface 1b side to thin it, and the workpiece 1 is divided along the planned division lines, a plurality of thin chips (device chips) each equipped with a device are manufactured. When the back surface 1b side of the workpiece 1 is ground, a tape-like protective member 3 having a diameter approximately the same as that of the workpiece 1 is attached to the front surface 1a side of the workpiece 1 to protect the front surface 1a side.

[0023] A grinding device is used to grind the workpiece 1. Next, the grinding device will be described. FIG. 1 is a perspective view showing a grinding device 2. The grinding device 2 has a substantially rectangular parallelepiped base 4 that supports each component. A recess 4a is formed on the upper surface of the base 4 along the Y-axis direction. The recess 4a is provided with a chuck table 6 that can hold the workpiece 1, and a dust-proof and drip-proof cover 4b that covers the opening of the recess 4a while exposing the chuck table 6.

[0024] A Y-axis movement mechanism (not shown) that movably supports the chuck table 6 is disposed inside the recess 4a. The Y-axis movement mechanism can move a moving table (not shown) on which the chuck table 6 is placed, along the Y-axis direction. The chuck table 6 has a ceramic frame 6a. A flow path (not shown) is provided inside the frame 6a, and one end of this flow path is connected to a suction source (not shown) such as an ejector.

[0025] The frame 6a has a recess on the upper surface thereof, which is a disk-shaped space. A roughly disk-shaped porous plate 6b is accommodated in this recess. The porous plate 6b has roughly flat circular lower and upper surfaces. The diameter of the porous plate 6b is roughly the same as the diameter of the workpiece 1. The other end of the flow path of the frame 6a is connected to the lower surface side of the porous plate 6b. When the suction source is operated, a negative pressure is generated on the upper surface of the porous plate 6b, and the workpiece 1 is sucked and held by this upper surface. Therefore, the upper surface of the chuck table 6 functions as a holding surface 6c.

[0026] The upper end of a spindle (not shown) is connected to the lower surface side of the frame 6a of the chuck table 6, and a rotation drive source (not shown) such as a motor for rotating the spindle is provided at the lower end of the spindle. By operating this rotation drive source, the chuck table 6 rotates around a rotation axis that intersects with the holding surface 6c.

[0027] The grinding apparatus 2 includes a grinding unit 22 that grinds the workpiece 1 held by the chuck table 6. The grinding apparatus 2 also includes a grinding feed unit (Z-axis movement mechanism) 24 that relatively feeds the grinding unit 22 and the chuck table 6 along the Z-axis direction for grinding. In the grinding apparatus 2 shown in FIG. 1, the grinding feed unit 24 raises and lowers the grinding unit 22.

[0028] A support part 26 is provided in an upright position on the rear side of the grinding device 2, and the grinding unit 22 is supported by this support part 26 via the grinding feed unit 24. A pair of guide rails 28 extending along the Z-axis direction (vertical direction) are provided on the front side of the support part 26. A moving plate 30 is slidably attached to each guide rail 28.

[0029] A nut portion (not shown) is provided on the back surface side (rear surface side) of the moving plate 30, and a ball screw 34 parallel to the guide rail 28 is screwed into this nut portion. A pulse motor 36 is connected to one end of the ball screw 34. When the ball screw 34 is rotated by the pulse motor 36, the moving plate 30 moves in the Z-axis direction along the guide rail 28.

[0030] The grinding unit 22 is fixed to the front side of the movable plate 30. By moving the movable plate 30, the grinding unit 22 can move in the Z-axis direction (grinding feed direction). The grinding unit 22 has a cut cylindrical holding member 38. The holding member 38 is fixed to the surface on the front side of the movable plate 30.

[0031] A spindle housing 40 is provided inside the holding member 38. The spindle housing 40 is supported on the bottom surface of the holding member 38. A portion of a spindle 44 is rotatably housed in the spindle housing 40. A rotational drive source (not shown) such as a motor is connected to the upper end of the spindle 44. When the rotational drive source is operated, the spindle 44 rotates around the direction in which the spindle 44 extends.

[0032] The lower end of the spindle 44 is located below the bottom of the holding member 38. The upper surface of a disk-shaped wheel mount 48 is connected to the lower end of the spindle 44. The upper surface of a circular grinding wheel 50 is attached to the lower surface of the wheel mount 48.

[0033] The grinding wheel 50 has an annular wheel base 52. The wheel base 52 is made of a metal such as aluminum, and has a diameter corresponding to the diameter of the workpiece 1. The upper surface side of the wheel base 52 is connected to the lower surface side of the wheel mount 48. In other words, the grinding wheel 50 is attached to the spindle 44 via the wheel mount 48.

[0034] A plurality of grinding wheels 54 are provided in an annular shape on the lower surface (one surface) side of the wheel base 52. Each grinding wheel 54 is formed by mixing abrasive grains such as diamond or cBN (cubic boron nitride) with a binder such as vitrified or resinoid, and sintering the mixture. When the spindle 44 is rotated to rotate the grinding wheel 50, the grinding wheels 54 rotate and move on an annular orbit.

[0035] The grinding device 2 includes a thickness measuring unit 56 capable of measuring the thickness of the workpiece 1, and grinds the workpiece 1 with the grinding unit 22 while monitoring the thickness of the workpiece 1 with the thickness measuring unit 56. FIG. 2 is a perspective view showing a schematic view of the thickness measuring unit 56.

[0036] The thickness measuring unit 56 is composed of a first height gauge 62 that measures the height of the upper surface of the chuck table 6, and a second height gauge 64 that measures the height of the upper surface of the workpiece 1 held by the chuck table 6. That is, the grinding device 2 is equipped with the first height gauge 62 and the second height gauge 64.

[0037] More specifically, the thickness measurement unit 56 includes an axis portion 58 standing along the Z-axis direction from the upper surface of the base 4, and an arm portion 60 extending horizontally (along the XY plane) from the upper end of the axis portion 58. A first height gauge 62 and a second height gauge 64 are supported by the arm portion 60 above the recessed portion 4a of the base 4.

[0038] The first height gauge 62 is fixed to the arm 60 at a position overlapping the upper surface of the frame 6a of the chuck table 6. From another perspective, the first height gauge 62 is fixed to the arm 60 at a position overlapping a portion of the chuck table 6 that is not covered by the workpiece 1. From yet another perspective, the first height gauge 62 is fixed to the arm 60 at a position not overlapping the porous plate 6b. In addition, the second height gauge 64 is fixed to the arm 60 at a position overlapping a portion of the workpiece 1 that is ground by the grinding unit 22 and is exposed from the grinding unit 22 (grinding wheel 50).

[0039] The first height gauge 62 and the second height gauge 64 are configured similarly, and therefore will be described together. Fig. 3(A) is a projection diagram that shows the height gauges 62 and 64 in a schematic manner, and Fig. 3(B) is a projection diagram that shows a portion of the height gauges 62 and 64 in a schematic manner.

[0040] The height gauges 62, 64 include lifting bodies 70, 72 that can rise and fall along the Z-axis direction, and cylindrical bodies 66, 68 that house the lifting bodies 70, 72 so that they can rise and fall. The cylindrical bodies 66, 68 are fixed to the arm 60. The upper ends of support parts 74, 76 that extend along the Z-axis direction are fixed to the lower surfaces of the lifting bodies 70, 72, and probes 78, 80 are fixed to the lower ends of the support parts 74, 76.

[0041] A linear scale (height indication) 82 is disposed along the Z-axis direction on the outer peripheral surface of the lifting bodies 70, 72. A reader (reader) 84 is incorporated in the cylindrical bodies 66, 68 at a position exposed on the inner peripheral surface and facing the linear scale 82.

[0042] The reader 84 includes, for example, a light source (not shown) that can irradiate the linear scale 82 with illumination light, and a sensor (not shown) that receives light reflected by the linear scale 82. The light source of the reader 84 is, for example, an LED, etc. The sensor of the reader 84 is, for example, a CMOS sensor, a CCD sensor, etc. The reader 84 obtains information regarding the heights of the lifting bodies 70, 72 and the measuring probes 78, 80 by reading the linear scale 82.

[0043] The height gauges 62, 64 can measure the height of the top surface of the object to be measured. When measuring the height of the top surface of the object to be measured, the probes 78, 80 are placed on the top surface of the object to be measured. At this time, the lifting bodies 70, 72 rise and fall according to the height of the top surface of the object to be measured. In other words, the height of the lifting bodies 70, 72 is determined by the height of the top surface of the object to be measured. Therefore, the height of the top surface of the object to be measured can be measured by reading the linear scale 82 with the reader 84 and measuring the height of the lifting bodies 70, 72, etc.

[0044] While the grinding unit 22 is grinding the workpiece 1, the thickness measuring unit 56 brings the probe 78 of the first height gauge 62 into contact with the upper surface of the chuck table 6 and the probe 80 of the second height gauge 64 into contact with the surface to be ground (rear surface 1b) of the workpiece 1. This obtains the height of the upper surface of the chuck table 6 and the height of the surface to be ground of the workpiece 1. Then, by subtracting the height of the upper surface of the chuck table 6 from the height of the surface to be ground of the workpiece 1, information regarding the thickness of the workpiece 1 can be obtained.

[0045] In addition, when the protective member 3 is attached to the surface 1a of the workpiece 1, the sum of the thickness of the workpiece 1 and the thickness of the protective member 3 is calculated by subtracting the height of the upper surface of the chuck table 6 from the height of the grinding surface of the workpiece 1. Therefore, the thickness of the protective member 3 is obtained in advance, and the thickness of the workpiece 1 can be calculated by subtracting the height of the upper surface of the chuck table 6 from the height of the grinding surface of the workpiece 1, and then further subtracting the thickness of the protective member 3.

[0046] For example, the thickness measuring unit 56 may include a calculation section that performs such calculation, and the thickness of the workpiece 1 calculated by the calculation section can be output. In this case, the calculation section is realized by a microcomputer or the like incorporated in the thickness measuring unit 56. However, the calculation section is not limited to this.

[0047] The grinding device 2 includes a controller (control unit) 88 that controls each of the components. The controller 88 is configured by a computer including, for example, a processing device such as a central processing unit (CPU), a main storage device such as a dynamic random access memory (DRAM), and an auxiliary storage device such as a hard disk drive or a flash memory. The functions of the controller 88 are realized by operating the processing device and the like in accordance with software stored in the auxiliary storage device. However, the functions of the controller 88 may be realized only by hardware.

[0048] The controller 88 includes a control unit 90 that controls, for example, the chuck table 6, the grinding unit 22, the Y-axis movement mechanism, the grinding feed unit 24, the thickness measurement unit 56, etc. The control unit 90 sends predetermined commands to each of these components, and performs grinding of the workpiece 1 under predetermined grinding conditions.

[0049] The controller 88 may include a calculation unit 92 that controls the thickness measuring unit 56 to calculate the thickness of the workpiece 1. The calculation unit 92 calculates the thickness of the workpiece 1 based on the difference between the height of the upper surface of the chuck table 6 measured by the first height gauge 62 and the height of the upper surface (surface to be ground, back surface 1b) of the workpiece 1 measured by the second height gauge 64. When the controller 88 includes the calculation unit 92, the thickness measuring unit 56 does not need to include a calculation unit.

[0050] When grinding the workpiece 1 with the grinding device 2, the workpiece 1, which has a tape-like protective member 3 attached to its front surface 1a, is placed on the holding surface 6c of the chuck table 6 via the protective member 3. The workpiece 1 is then held by suction on the chuck table 6, and the back surface 1b of the workpiece 1, which will be the surface to be ground, is exposed upward. The Y-axis movement mechanism is then operated to move the chuck table 6 to below the grinding unit 22.

[0051] Thereafter, the grinding wheel 50 and the chuck table 6 are rotated around their respective rotation axes, and the grinding feed unit (Z-axis movement mechanism) 24 is operated to start the downward movement of the grinding unit 22. Then, when the lower surface of the grinding stone 54 moving on the circular orbit comes into contact with the back surface 1b of the workpiece 1, grinding of the workpiece 1 begins.

[0052] During grinding of the workpiece 1, friction between the workpiece 1 and the grinding wheel 54 generates frictional heat. If the temperature of the workpiece 1, the grinding wheel 54, etc. changes due to frictional heat, they may expand thermally or the processing conditions may change, and the desired grinding results may not be obtained. During grinding, the workpiece 1 and the grinding wheel 54 are worn out and processing waste is generated. Therefore, during grinding of the workpiece 1, grinding water composed of pure water or the like is supplied to the workpiece 1 and the grinding wheel 54, and the processing waste and frictional heat are removed by the grinding water.

[0053] The grinding device 2 continues to lower the grinding unit 22 while monitoring the thickness of the workpiece 1 with the thickness measuring unit 56. Thereafter, when the thickness of the workpiece 1 reaches a predetermined finishing thickness, the grinding unit 22 stops lowering and raises the grinding unit 22. Then, the workpiece 1 thinned to the finishing thickness is obtained.

[0054] Here, the height gauges 62, 64 of the thickness measurement unit 56 have probes 78, 80 that come into contact with the upper surface of the workpiece 1 or the chuck table 6. The bottom surfaces of the probes 78, 80 become the contact surfaces that come into contact with the upper surface of the measurement target, such as the workpiece 1. Since the chuck table 6 supporting the workpiece 1 rotates while the workpiece 1 is being ground, the probes 78, 80 that come into contact with the upper surface of the workpiece 1 or the like are worn out from the contact surface side due to friction. Therefore, the probes 78, 80 of the height gauges 62, 64 are replaced periodically.

[0055] When the probes 78, 80 come into contact with the upper surface of the object to be measured, it is assumed that the bottom surface of the probes 78, 80 faces the upper surface of the object to be measured. In other words, it is assumed that the bottom surface of the probes 78, 80 and the upper surface of the object to be measured are parallel to each other. However, when the probes 78, 80 are attached to the height gauges 62, 64, a certain error occurs in the orientation of the probes 78, 80. In addition, a certain error also exists in the orientation of the chuck table 6.

[0056] Fig. 4 includes a side view that shows a schematic of the probes 78, 80 immediately after they have been attached to the height gauges 62, 64. In the example shown in Fig. 4, the supports 74, 76 that support the probes 78, 80 are tilted from the Z-axis direction, which causes the orientation of the probes 78, 80 to deviate from the expected direction.

[0057] In addition, in Fig. 4 and the like, the inclination of the probes 78, 80 is emphasized for the convenience of explanation. Therefore, the inclination of the probes 78, 80 is not limited to the magnitude shown in the figures. Even if the probes 78, 80 are appropriately attached to the height gauges 62, 64, a tilt of about 0.05° to 0.1° may occur.

[0058] When the probe 78 of the first height gauge 62 and the upper surface of the chuck table 6 are inclined relative to each other, a corner or sharp part of the bottom surface of the unworn probe 78 comes into contact with the upper surface of the chuck table 6. When the probe 80 of the second height gauge 64 and the ground surface (back surface 1b) of the workpiece 1 are inclined relative to each other, a corner or sharp part of the bottom surface of the unworn probe 80 comes into contact with the ground surface of the workpiece 1.

[0059] That is, in the initial stage of using the probes 78, 80, the contact area of ​​the probes 78, 80 that comes into contact with the top surface of the object to be measured is small. Therefore, the probes 78, 80 are significantly worn down by contact with the rotating object to be measured. When the wear of the probes 78, 80 progresses significantly, the lifting bodies 70, 72 are lowered by an amount that greatly exceeds the amount of reduction in the height of the top surface of the object to be measured. Therefore, the height gauges 62, 64 are no longer able to correctly measure the height of the object to be measured, and the measurement accuracy of the height gauges 62, 64 is reduced.

[0060] To address this problem, in the conventional grinding device 2, frequent calibration of the height gauges 62, 64 was required, especially immediately after replacing the gauges 78, 80. During the calibration of the height gauges 62, 64, grinding of the workpiece 1 cannot be performed while referring to the height gauges 62, 64, which was also a factor in reducing the efficiency of machining the workpiece 1.

[0061] In contrast, in the height gauge adjustment method and grinding apparatus of this embodiment, the first height gauge 62 and the second height gauge 64 are adjusted as described below, thereby suppressing a decrease in measurement accuracy without performing calibration work.

[0062] The height gauge adjustment method and grinding device according to this embodiment will be described in more detail below, focusing on the configuration related to the adjustment of the height gauges 62, 64. The grinding device according to this embodiment can implement the height gauge adjustment method described below. Therefore, the description of the height gauge adjustment method below is referred to as a description of the operation mode of the grinding device according to this embodiment.

[0063] A dresser board used for dressing the grinding wheel 54 is used to adjust the height gauges 62, 64. When an unused grinding wheel 54 or a grinding wheel 54 with reduced grinding ability is dressed with a dresser board, the grinding wheel 54 wears appropriately and a new machined surface appears on the bottom surface, so that the grinding wheel 54 can obtain a specified grinding ability.

[0064] Fig. 1 includes a perspective view that typically shows the dresser board 5. Fig. 4 and other figures include a cross-sectional view that typically shows a portion of the dresser board 5. The dresser board 5 has upper and lower surfaces that are parallel to each other, and has abrasive grains such as white alundum (WA) and green carbon (GC), and a binder such as vitrified or resinoid for fixing the abrasive grains. However, the abrasive grains and binder that constitute the dresser board 5 are appropriately selected depending on the type of the object to be dressed.

[0065] The configuration of the dresser board 5 is preferably selected so as to allow good adjustment of the height gauges 62, 64, and may be configured inappropriately for dressing the grinding wheel 54. From another perspective, it is preferable that the dresser board 5 wears the probes 78, 80 of the height gauges 62, 64 more than the grinding wheel 54. For example, the dresser board 5 may be a dedicated product for adjusting the height gauges 62, 64. However, the configuration of the dresser board 5 is not limited to this.

[0066] Fig. 7 is a flowchart showing the flow of each step of the height gauge adjustment method according to this embodiment. In the height gauge adjustment method according to this embodiment, first, a holding step S10 is performed in which the dresser board 5 is held by the chuck table 6. Fig. 4 is a cross-sectional view showing the chuck table 6 and the dresser board 5 in the holding step S10.

[0067] In the holding step S10, first, the dresser board 5 is placed on the upper surface of the chuck table 6. Then, the suction source of the chuck table 6 is operated to suction-hold the dresser board 5 on the chuck table 6. At this time, a wide area of ​​the upper surface of the chuck table 6, including the holding surface 6c of the chuck table 6, is covered with the dresser board 5.

[0068] In general, the holding surface 6c formed by the upper surface of the porous plate 6b has the same diameter as the workpiece 1. Therefore, when the workpiece 1 is placed on the chuck table 6 for grinding, the upper surface of the frame 6a of the chuck table 6 is exposed from the workpiece 1. Then, when the workpiece 1 is ground, the probe 78 of the first height gauge 62 is brought into contact with the exposed upper surface of the frame 6a to measure the height of the upper surface of the chuck table 6.

[0069] In contrast, in the height gauge adjustment method according to this embodiment, the probe 78 of the first height gauge 62 overlapping with the upper surface of the frame body 6a is brought into contact with the dresser board 5. Therefore, in the holding step S10, the upper surface of the frame body 6a is also covered with the dresser board 5. In particular, the area of ​​the upper surface of the frame body 6a that comes into contact with the probe 78 is covered with the dresser board 5. Therefore, it is preferable that the dresser board 5 be in the shape of a disk having a diameter larger than that of the workpiece 1, which has a diameter equivalent to that of the porous plate 6b.

[0070] After the holding step S10, a wearing step S20 is performed in which the probe 78 of the first height gauge 62 and the probe 80 of the second height gauge 64 are brought into contact with the dresser board 5 and worn. Fig. 5 is a cross-sectional view showing the chuck table 6 and the dresser board 5 in the wearing step S20. Fig. 5 includes a side view showing a part of the first height gauge 62 and a part of the second height gauge 64 of the thickness measuring unit 56.

[0071] In the wear step S20, the chuck table 6 is rotated around a rotation axis intersecting the holding surface 6c. Then, the first height gauge 62 and the second height gauge 64 of the thickness measuring unit 56 are lowered so that the probes 78, 80 come into contact with the upper surface of the dresser board 5. The first height gauge 62 and the second height gauge 64 are lowered by the weight of the lifting bodies 70, 72.

[0072] When the probes 78, 80 first come into contact with the dresser board 5, the corners and sharp parts of the bottom surfaces of the tilted probes 78, 80 hit the dresser board 5, causing wear to the probes 78, 80. At this time, the probes 78, 80 are worn down so that the shape of the bottom surfaces of the probes 78, 80 corresponds to the shape of the upper surface of the dresser board 5.

[0073] Therefore, a bottom surface parallel to the upper surface of the dresser board 5 (parallel to the upper surface of the chuck table 6) is formed at the lower end of the probes 78, 80, and the contact area between the probes 78, 80 and the dresser board 5 increases. Even if an error occurs in the orientation of the probes 78, 80 or the orientation of the chuck table 6, the bottom surfaces of the probes 78, 80 after wear are shaped to face directly against the upper surface of the dresser board 5.

[0074] In addition, in the wearing step S20, the probes 78, 80 may be pressed against the dresser board 5. When the probes 78, 80 are pressed against the dresser board 5, wearing of the probes 78, 80 is promoted, and the wearing step S20 can be completed early.

[0075] The pressure of the probes 78, 80 against the dresser board 5 may be implemented, for example, by attaching weights to the height gauges 62, 64. The height gauges 62, 64 may also be provided with a mechanism capable of controlling the force applied to an object in contact with the probes 78, 80, and the probes 78, 80 may be pressed against the dresser board 5 by operating the mechanism.

[0076] For example, in the height gauges 62, 64 equipped with this mechanism, the cylinders 66, 68 and the lifting bodies 70, 72 are configured as an air slider mechanism. The air slider mechanism includes a case that houses the air slider, an exhaust port that exhausts air exhausted from the air slider into the case to the outside of the case, and a valve that adjusts the amount of air exhausted from the exhaust port. The movement of the support parts 74, 76 can be adjusted by adjusting the pressure inside the case with the valve. This allows the pressing force of the probes 78, 80 against the dresser board 5 to be adjusted.

[0077] In the grinding device 2, after the abrasion step S20 is performed, the dresser board 5 is carried out from the chuck table 6, the workpiece 1 is suction-held by the chuck table 6, and the workpiece 1 is ground by the grinding unit 22. At this time, the thickness of the workpiece 1 is monitored by the thickness measuring unit 56. Fig. 6 is a cross-sectional view that shows a schematic view of the workpiece 1 being ground and thinned while the thickness is monitored by the thickness measuring unit 56.

[0078] When the bottom surfaces of the probes 78, 80 become parallel to the upper surface of the dresser board 5 by the wearing step S20, when the workpiece 1 is ground, the bottom surface of the probe 78 of the first height gauge 62 becomes parallel to the upper surface of the chuck table 6. Also, the upper surface of the workpiece 1 (the surface to be ground, the back surface 1b) becomes parallel to the bottom surface of the probe 80 of the second height gauge 64. Therefore, the probes 78, 80 come into contact with the upper surfaces of the respective objects to be measured over a wide area.

[0079] In this case, even when grinding the workpiece 1 while monitoring the thickness of the workpiece 1 using the height gauges 62, 64 equipped with the probes 78, 80 that have just been used, the amount of wear on the probes 78, 80 is relatively small. Therefore, the measurement accuracy of the height gauges 62, 64 of the thickness measuring unit 56 is not likely to decrease, and there is no need to frequently calibrate the height gauges 62, 64 even immediately after replacing the probes 78, 80.

[0080] The above-mentioned height gauge adjustment method performed by the grinding apparatus 2 may be performed by the function of a controller (control unit) 88 of the grinding apparatus 2. For example, the controller 88 may further include an adjustment unit 94 (see FIG. 1) that adjusts the first height gauge 62 and the second height gauge 64. The adjustment unit 94 controls each component of the grinding apparatus 2 to mainly perform the above-mentioned wear step S20.

[0081] When the dresser board 5 is placed on the chuck table 6, the adjustment unit 94 causes the chuck table 6 to suction-hold the dresser board 5. Then, while rotating the chuck table 6 around an axis intersecting the upper surface, the probe 78 of the first height gauge 62 and the probe 80 of the second height gauge 64 are brought into contact with the dresser board 5 and worn down. This allows the shapes of the bottom surfaces of the probes 78, 80 to be adjusted, and the first height gauge 62 and the second height gauge 64 to be adjusted.

[0082] As described above, in the height gauge adjustment method and grinding apparatus 2 according to this embodiment, the dresser board 5 is used to wear down the probes 78, 80, thereby reducing the frequency of calibration work caused by wear of the probes 78, 80 during actual use. Therefore, it is possible to minimize the decrease in the processing efficiency of the workpiece 1 caused by the calibration work of the height gauges 62, 64. When the dresser board 5 is used, wear of the probes 78, 80 progresses early, so that adjustment of the probes 78, 80 can be completed in a short time.

[0083] In the above embodiment, the probes 78, 80 of the height gauges 62, 64 of the thickness measurement unit 56 are illustrated and described as being block-shaped as shown in Figures 2, 3, 4, etc., but one aspect of the present invention is not limited to this. For example, the probes 78, 80 of the height gauges 62, 64 may be shaped like an inverted pyramid with the lower end as the apex, or may be rod-shaped or needle-shaped along the Z-axis direction.

[0084] Regardless of the shape of the probes 78, 80, when an unused probe 78, 80 is worn and shaped on the dresser board 5, a bottom surface parallel to the top surface of the object to be measured can be formed on the probes 78, 80. Therefore, when the probes 78, 80 are subsequently brought into contact with the top surface of the object to be measured while the chuck table 6 is being rotated, wear of the probes 78, 80 does not progress significantly, and the measurement accuracy of the thickness measuring unit 56 is less likely to decrease.

[0085] In the above embodiment, the case where the height gauges 62, 64 need to be adjusted because the supports 74, 76 are inclined from the Z-axis direction as shown in Fig. 4 etc. has been described as an example, but the aspect of the present invention is not limited to this. The adjustment method etc. according to one aspect of the present invention is effective in cases where the height gauges 62, 64 need to be adjusted because of the inclination of the chuck table 6, the attachment error of the probes 78, 80, etc.

[0086] In the above embodiment, the description has been given of wearing only the probes 78, 80 on the dresser board 5 of the height gauges 62, 64 in the wearing step S20, but one aspect of the present invention is not limited to this.

[0087] For example, in the wearing step S20, the height gauges 62, 64 may be adjusted and the grinding wheel 54 may be dressed by the dresser board 5. That is, in the wearing step S20, the probe 78 of the first height gauge 62 and the probe 80 of the second height gauge 64 may be brought into contact with the dresser board 5 to be worn, and the grinding wheel 54 may be brought into contact with the dresser board 5 to be dressed.

[0088] In this case, adjustment of the height gauges 62, 64 and dressing of the grinding wheel 54 are performed simultaneously, so that the time required for maintenance of the grinding device 2 can be shortened and the efficiency of processing the workpiece 1 can be further improved. In this case, the dresser board 5 is preferably configured so that both adjustment of the height gauges 62, 64 and dressing of the grinding wheel 54 can be performed.

[0089] The structures, methods, and the like according to the above-described embodiments can be modified as appropriate without departing from the scope of the object of the present invention. [Explanation of symbols]

[0090] 1 Workpiece 1a surface 1b back side 3 Protective materials 5. Dresser Board 2 Grinding equipment 4 Foundation 4a Recess 4b Dust-proof / water-proof cover 6 Chuck table 6a Frame 6b Porous plate 6c Holding surface 22 Grinding unit 24 Grinding feed unit 26 Support part 28 Guide rail 30 Moving Plate 34 Ball screw 36 Pulse motor 38 Retaining member 40 Spindle housing 44 Spindle 48 Wheel mount 50 Grinding Wheel 52 Wheel base 54 Grinding Wheel 56 Thickness measurement unit 58 Shaft 60 Arm 62,64 Height gauge 66,68 Cylinder 70,72 Lifting body 74,76 Support part 78,80 Probe 82 Linear Scale 84 Leader 88 Controller 90 Control section 92 Calculation section 94 Adjustment part

Claims

1. A chuck table for holding the workpiece; a grinding unit that grinds the workpiece held by the chuck table; a grinding feed unit for relatively feeding the grinding unit and the chuck table; a first height gauge for measuring the height of an upper surface of the chuck table; a second height gauge for measuring the height of an upper surface of the workpiece held by the chuck table; a calculation unit that calculates a thickness of the workpiece based on a difference between a height of the upper surface of the chuck table measured by the first height gauge and a height of the upper surface of the workpiece measured by the second height gauge; A method for adjusting the first height gauge and the second height gauge in a grinding apparatus comprising: a holding step of holding the dresser board on the chuck table; a wearing step of bringing the gauge head of the first height gauge and the gauge head of the second height gauge into contact with the dresser board and wearing them; An adjustment method comprising:

2. 2. The method according to claim 1, wherein the dresser board is in the shape of a disk having a diameter larger than that of the workpiece.

3. A chuck table for holding the workpiece; a grinding unit that grinds the workpiece held by the chuck table; a grinding feed unit for relatively feeding the grinding unit and the chuck table; a first height gauge for measuring the height of an upper surface of the chuck table; a second height gauge for measuring the height of an upper surface of the workpiece held by the chuck table; a calculation unit that calculates a thickness of the workpiece based on a difference between a height of the upper surface of the chuck table measured by the first height gauge and a height of the upper surface of the workpiece measured by the second height gauge; an adjustment unit that adjusts the first height gauge and the second height gauge, a grinding device characterized in that, when a dresser board is placed on the chuck table, the adjustment unit sucks and holds the dresser board on the chuck table, and rotates the chuck table around an axis intersecting the upper surface while bringing a measuring element of the first height gauge and a measuring element of the second height gauge into contact with the dresser board and causing them to wear, thereby adjusting the first height gauge and the second height gauge.

4. 4. The grinding apparatus according to claim 3, wherein the dresser board is in the shape of a disk having a diameter larger than that of the workpiece.

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