Grinding Equipment

Abstract

To grind a workpiece held by a chuck table while measuring the height of an upper surface of the workpiece even if the thickness of the workpiece before grinding exceeds a measuring range of an upper surface measuring instrument.SOLUTION: A grinding apparatus acquires a ground-off quantity of a wafer 5 by subtracting a wear amount |(H0-H1)| of a grind stone 77, which is acquired by means of an upper surface height measuring instrument 80 that is lifted and lowered along with a grinding mechanism 70, from a lowering amount |(Z0-Z1)| of the grinding mechanism 70, which is acquired by means of a Z-axis encoder 65. Since the ground-off quantity of the wafer 5 is measured using the upper surface height measuring instrument 80 and the Z-axis encoder 65, it is not necessary to obtain the ground-off quantity of the wafer 5 only by an upper surface height measuring instrument provided on a base 3 as in the conventional art. Therefore, even if the thickness of the wafer 5 before grinding or the ground-off quantity of the wafer 5 exceeds the measurement range of the upper surface height measuring instrument 80, the wafer 5 can be ground while measuring the ground-off quantity of the wafer 5 held by a chuck table 20.SELECTED DRAWING: Figure 4

Description

[Technical field]

[0001] The present invention relates to a grinding device. [Background technology]

[0002] In a grinding device that uses a grinding wheel to grind a workpiece held by the holding surface of a chuck table, as disclosed in Patent Documents 1 and 2, the height of the holding surface and the height of the top surface of the workpiece are measured, the difference between the height of the holding surface and the height of the top surface of the workpiece is calculated, and the workpiece is ground until this difference reaches a predetermined thickness. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] JP 2008-073785 A [Patent Document 2] JP 2019-130607 A [Patent Document 3] JP 2021-020269 A Summary of the Invention [Problem to be solved by the invention]

[0004] In the above-mentioned technique, when the thickness of the workpiece before grinding is large, it is necessary to use a measuring device with a long measuring range to measure the height of the upper surface of the workpiece. However, since a measuring device with a long measuring range is expensive, the processing device becomes expensive.

[0005] Furthermore, as disclosed in Patent Document 3, when grinding the top surface of a cylindrical ingot, the grinding is performed while measuring the amount by which the top surface height of the workpiece is lowered. In addition, since the grinding wheel presses the workpiece while grinding, it is desirable to measure the top surface height of the workpiece near the trajectory of the grinding wheel.

[0006] Therefore, an object of the present invention is to grind a workpiece while measuring the top surface height of the workpiece held by the chuck table, even if the thickness of the workpiece before grinding exceeds the measurement range of the top surface measuring device. [Means for solving the problem]

[0007] The grinding device of the present invention (the present grinding device) is a grinding device comprising: a chuck table whose holding surface holds a workpiece; a grinding mechanism that grinds the top surface of the workpiece held by the holding surface with a grinding wheel; a grinding feed mechanism that raises and lowers the grinding mechanism in a direction perpendicular to the holding surface; a height position recognition unit that recognizes the height position of the grinding mechanism raised and lowered by the grinding feed mechanism; an upper surface height measuring device that measures the height of the top surface of the workpiece held by the holding surface; and a control unit, wherein the upper surface height measuring device is raised and lowered by the grinding feed mechanism together with the grinding mechanism in the direction perpendicular to the holding surface. the control unit is configured to define a value of the height of a horizontal plane that is the same as the lower surface of the grinding wheel, measured by the upper surface height measuring device, as H0, a height of the grinding mechanism recognized by the height position recognizing unit when the lower surface of the grinding wheel comes into contact with the workpiece, as Z0, a height of the grinding mechanism recognized by the height position recognizing unit that changes downward when the grinding mechanism is lowered to grind the workpiece, as Z1, and a measurement value of the upper surface height measuring device that changes due to wear of the grinding wheel when the workpiece is grinded, as H1, and a calculation unit that calculates a first calculation value during grinding using the following formula: |(Z0-Z1)|-|(H0-H1)|=First calculated value The workpiece is ground until the first calculation value calculated by the calculation unit becomes equal to a preset grinding amount. In this grinding device, the control unit may be provided with an upper surface height measuring device origin memory unit that stores the value (H0) of the height of the same horizontal plane as the lower surface of the grinding wheel, measured by the upper surface height measuring device, and the grinding mechanism may be lowered using the grinding feed mechanism from above the workpiece held by the holding surface, and when the measurement value of the upper surface height measuring device matches the value (H0) stored in the upper surface height measuring device origin memory unit, it may be determined that the lower surface of the grinding wheel has come into contact with the upper surface of the workpiece. The grinding apparatus may further comprise a holding surface height measuring device that is disposed on a base for arranging the chuck table and the grinding mechanism and that measures the height of the holding surface, and a holding surface height origin memory unit that stores a value (P0) measured by the holding surface height measuring device when no vertical load is applied to the holding surface, and the control unit sets the measurement value of the holding surface height measuring device, which changes downward due to sinking of the chuck table, as P1 when grinding a workpiece, and the calculation unit calculates a second calculation value during grinding using the following formula: |(Z0-Z1)|-|(H0-H1)|-|(P1-P0)|=Second calculated value The control unit may grind the workpiece until the second calculated value reaches a preset grinding amount. Effect of the Invention

[0008] In this grinding device, the amount of wear of the grinding wheel |(H0-H1)|, which is obtained using a top surface height measuring device that rises and falls together with the grinding mechanism, is obtained from the amount of descent of the grinding mechanism |(Z0-Z1)|, which is obtained using the height position recognition unit during grinding, to obtain the amount of grinding of the workpiece that has been ground.

[0009] In this way, in this grinding device, the grinding amount of the workpiece is measured using the height position recognition unit and the top surface height measuring device that rises and falls together with the grinding mechanism. Therefore, it is not necessary to obtain the grinding amount of the workpiece only by the top surface height measuring device provided on a base for placing a chuck table or the like, as in the conventional case. Therefore, even if the thickness of the workpiece before grinding or the grinding amount of the workpiece exceeds the measurement range of the top surface height measuring device, it is possible to grind the workpiece while measuring the grinding amount of the workpiece held by the chuck table.

[0010] Therefore, in this grinding device, even if the measurement range of the upper surface height measuring device is not long, it is possible to measure the amount of grinding of a thick workpiece such as an ingot, and even if the workpiece is thin, it is possible to measure the amount of grinding. Therefore, it is not necessary to provide an expensive measuring device with a long measurement range in order to grind a thick workpiece. Therefore, it is possible to reduce the cost of this grinding device. [Brief description of the drawings]

[0011] [Figure 1] FIG. 2 is an explanatory diagram showing a configuration of a grinding device. [Diagram 2] FIG. 2 is a perspective view showing a configuration of an upper surface height measuring device. [Diagram 3] FIG. 2 is a cross-sectional view showing the configuration of an upper surface height measuring device. [Figure 4] FIG. 4 is an explanatory diagram showing the amount of wafer grinding. [Diagram 5] FIG. 11 is an explanatory diagram showing an example of using a setup block. [Figure 6] FIG. 4 is an explanatory diagram showing the amount of wafer grinding. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0012] As shown in FIG. 1, a grinding apparatus 1 according to this embodiment is an apparatus for grinding a wafer 5 as a workpiece.

[0013] The grinding apparatus 1 includes a chuck table 20 whose holding surface 22 holds the wafer 5 . The chuck table 20 includes a porous member 21 and a frame 23 that exposes the upper surface of the porous member 21 and houses the porous member 21. The upper surface of the porous member 21 is a holding surface 22 that holds the wafer 5 by suction. The holding surface 22 is connected to a suction source to hold the wafer 100 by suction. A frame surface 24 that is the upper surface of the frame 23 is formed flush with the holding surface 22.

[0014] Further, a table base 55 that supports the chuck table 20 is provided below the chuck table 20. Further, below the table base 55, a table rotation mechanism 50 that rotatably supports the table base 55 is provided.

[0015] The table rotating mechanism 50 includes a motor 521, a driving pulley 522 attached to the motor 521, a driven pulley 524 connected to the driving pulley 522 via an endless belt 523, and a rotary joint 525 disposed below the driven pulley 524. The driven pulley 524 is supported by a narrow-diameter portion of the lower part of the table base 55.

[0016] In the table rotating mechanism 50, a motor 521 rotates a driving pulley 522, thereby rotating an endless belt 523 and a driven pulley 524. As a result, the table base 55 and the chuck table 20 are rotated as shown by an arrow 502.

[0017] Further, around the periphery of the table base 55, a tilt adjustment mechanism 40 for adjusting the tilt of the chuck table 20 is provided.

[0018] The inclination adjustment mechanism 40 includes an internal base 41 arranged below the chuck table 20 , an inclination adjustment shaft 42 , a fixed shaft 43 fixed to the internal base 41 , and an annular member 45 .

[0019] The annular member 45 rotatably supports the table base 55 so as to surround the table base 55 via a connecting portion 46 including a bearing.

[0020] The fixed shaft 43 has its upper end fixed to the lower surface of the annular member 45 and its lower end fixed to the upper surface of the internal base 41 .

[0021] The inclination adjustment shaft 42 is disposed between the inner base 41 and the annular member 45, and can move a part of the annular member 45 up and down along the Z-axis direction. This allows the inclination of the chuck table 20 to be adjusted. The annular member 45 is supported by the internal base 41 at three points, and at least one of the three points is the inclination adjustment shaft 42. It is also possible to not have the fixed shaft 43 and have the inclination adjustment shaft 42 at all three locations.

[0022] In addition, a flow path 243 is connected to the chuck table 20, and a suction source 240, an air supply source 241, and a water supply source 242 are connected to the flow path 243 via a suction valve 270, an air valve 271, and a water valve 272, respectively. This allows the grinding device 1 to supply air or water to the porous member 21 of the chuck table 20 and to apply suction force from the suction source 240 to the holding surface 22 of the porous member 21 .

[0023] Further, a column 11 is provided upright on the +Y direction side of the chuck table 20. The column 11 is provided with a grinding mechanism 70 that grinds the wafer 5, and a grinding feed mechanism 60.

[0024] The grinding feed mechanism 60 raises and lowers the grinding mechanism 70 in the Z-axis direction which is a direction perpendicular to the holding surface 22 of the chuck table 20. The grinding feed mechanism 60 includes a Z-axis guide rail 61 parallel to the Z-axis direction, a Z-axis moving table 63 which slides on the Z-axis guide rail 61, a Z-axis ball screw 62 parallel to the Z-axis guide rail 61, a Z-axis motor 64, and a Z-axis encoder 65 for detecting the rotation angle of the Z-axis motor 64. The grinding mechanism 70 is attached to the Z-axis moving table 63.

[0025] The Z-axis moving table 63 is slidably installed on the Z-axis guide rail 61 via a slide member 67. A nut portion 68 is fixed to the Z-axis moving table 63. A Z-axis ball screw 62 is screwed into the nut portion 68. The Z-axis motor 64 is connected to one end of the Z-axis ball screw 62.

[0026] In the grinding feed mechanism 60, the Z-axis motor 64 rotates the Z-axis ball screw 62, causing the nut portion 68 and the Z-axis moving table 63 to move up and down in the Z-axis direction along the Z-axis guide rail 61. As a result, the grinding mechanism 70 attached to the Z-axis moving table 63 also moves up and down in the Z-axis direction together with the Z-axis moving table 63.

[0027] The Z-axis encoder 65 also functions as a height position recognition unit, and by detecting the rotation angle of the Z-axis motor 64, recognizes the height position of the grinding mechanism 70 which is raised and lowered by the grinding feed mechanism 60. The Z-axis encoder 65 determines, as the height of the grinding mechanism 70, for example, the height of the nut portion 68 of the grinding feed mechanism 60 which moves in the Z-axis direction together with the grinding mechanism 70.

[0028] The grinding mechanism 70 grinds the upper surface 6 of the wafer 5 held by the holding surface 22 of the chuck table 20 with a grinding wheel 77. The grinding mechanism 70 includes a holder 79 fixed to the Z-axis moving table 63, a spindle housing 71 held by the holder 79, 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 72 extends along the Z-axis direction perpendicular to the holding surface 22 of the chuck table 20, and is supported by the spindle housing 71 so as to be rotatable about an axis along the extension direction. The spindle motor 73 is connected to the upper end side of the spindle 72, and rotates the spindle 72.

[0030] 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.

[0031] The grinding wheel 75 is formed so that its outer diameter is approximately the same as that of the wheel mount 74. The grinding wheel 75 includes an annular wheel base 76 made of a metal material. A processing water passage 761 is formed inside the wheel base 76 for supplying processing water from a water source (not shown) to the grinding wheel 77.

[0032] A plurality of grinding wheels 77 are fixed in an annular shape around the entire circumference of the underside of the wheel base 76. The grinding wheels 77 are rotated together with the spindle 72 by the spindle motor 73 around their center as an axis, and grind the upper surface 6 of the wafer 5 held on the chuck table 20.

[0033] The grinding apparatus 1 also has an upper surface height measuring device 80 that measures the upper surface height of the wafer 5 held by the holding surface 22 of the chuck table 20. The upper surface height measuring device 80 is disposed in the grinding mechanism 70 by being attached to a holder 79 of the grinding mechanism 70 by a mounting member 81. As a result, the upper surface height measuring device 80 moves up and down together with the grinding mechanism 70 in the Z-axis direction, which is a direction perpendicular to the holding surface 22. The upper surface height measuring device 80 only needs to be configured to move up and down in the Z-axis direction together with the grinding mechanism 70, and may be provided, for example, in a portion of the grinding feed mechanism 60 that moves up and down together with the grinding mechanism 70.

[0034] Furthermore, the grinding device 1 is equipped with a holding surface height measuring device 83 for measuring the height of the holding surface 22 of the chuck table 20. The holding surface height measuring device 83 is disposed on the base 3 on which the chuck table 20 and the grinding mechanism 70 are disposed.

[0035] Here, a description will be given of the configuration of the upper surface height measuring device 80. Note that the holding surface height measuring device 83 has a similar configuration to the upper surface height measuring device 80. The top surface height measuring device 80 shown in Figures 2 and 3 comprises a probe 110 that brings a tip 108 into contact with the top surface 6 of the wafer 5, a housing 112 serving as a guide that supports the probe 110 so that it can be raised and lowered by its own weight, and a scale 114 for reading the height position of the probe 110.

[0036] In this embodiment, the top surface height measuring instrument 80 further includes a moving mechanism 113 for moving the probe 110 along the Z-axis direction, a detection mechanism 115 for reading the graduations 140 of the scale 114, an exhaust port 116 and a throttle valve 117 for exhaust, and a case 101 as a housing.

[0037] The probe 110 has a measuring element 108 at one end (tip) and extends in the Z-axis direction which is a direction perpendicular to the holding surface 22. The other end of the probe 110 is connected to the connecting member 103.

[0038] Case 101 is supported from above by mounting member 81 shown in Fig. 1. Probe 110 is formed in a quadrangular prism shape and penetrates case 101, as shown in Fig. 2 and Fig. 3, with a measuring element 108 at the tip of probe 110 protruding downward from the bottom surface of case 101.

[0039] The housing 112 surrounds the side surface 111 of the probe 110 and supports the probe 110 in a non-contact manner so as to be movable in the Z-axis direction perpendicular to the holding surface 22 . That is, the housing 112 has a tube 120 that houses the probe 110. The tube 120 is disposed on the mounting surface 102 inside the case 101. The tube 120 is formed with a hole having a rectangular cross section for housing the probe 110 so as to correspond to the shape of the probe 110. The tube 120 is configured so that the probe 110 can be inserted into this hole to support the periphery of the probe 110 in a non-contact manner.

[0040] The cylinder 120 also has an inner support surface 121 and a plurality of nozzles 122 provided on the support surface 121. The support surface 121 faces the side surface 111 of the probe 110 at an equal distance from the side surface 111.

[0041] As shown in FIG. 3, the cylinder 120 is also provided with an inlet 123 connected to an air supply source (not shown), and flow paths 124 that connect the inlet 123 to each of the nozzles 122 .

[0042] In the housing 112, with the support surface 121 of the tube 120 facing the side surface 111 of the probe 110, air supplied to the inlet 123 is blown onto the side surface 111 of the probe 110 via the flow path 124 and the outlet 122 of the support surface 121. This allows the housing 112 to support the probe 110 with air interposed between the side surface 111 of the probe 110 and the support surface 121.

[0043] Furthermore, in the housing 112, air that has flowed into the cylinder 120 is exhausted from the upper exhaust port 125 and the lower exhaust port 126 of the cylinder 120. With this structure, the housing 112 can support the probe 110 in a non-contact manner so as to be movable in the Z-axis direction.

[0044] Exhaust port 116 is an exhaust port for exhausting air exhausted from housing 112 into case 101 to the outside of case 101. Throttle valve 117 connected to exhaust port 116 adjusts the amount of exhaust to adjust the pressure inside case 101, and adjusts the pressing pressure of probe 108 against top surface 6 of wafer 5.

[0045] The moving mechanism 113 is disposed near the probe 110 on the mounting surface 102 of the case 101. The moving mechanism 113 includes a cylinder 130 and a piston 131. The piston 131 moves inside the cylinder 130 in the Z-axis direction parallel to the axial direction of the probe 110.

[0046] Moreover, the movement mechanism 113 includes inlets 132 and 133 for allowing air to flow into the cylinder 130. The movement mechanism 113 having such a structure can move the probe 110 in the Z-axis direction via the connecting member 103 by linearly moving the piston 131 in the Z-axis direction.

[0047] That is, when the probe 110 is raised in the +Z direction by the movement mechanism 113, air from an air supply source (not shown) is supplied into the cylinder 130 via the inlet 132. This causes the piston 131 to rise inside the cylinder 130. Then, the piston 131 comes into contact with the connecting member 103 to raise the connecting member 103, causing the probe 110 connected to the connecting member 103 to rise.

[0048] On the other hand, when the probe 110 is lowered by the moving mechanism 113, air from an air supply source (not shown) is supplied into the cylinder 130 via the inlet 133. As a result, inside the cylinder 130, the probe 110 is lowered by the weight of the probe 110 and the connecting member 103 connected to the probe 110.

[0049] Moreover, the moving mechanism 113 can adjust the amount of air flowing in from the inlet 133 to adjust the descending speed of the piston 131, thereby limiting the descending speed of the probe 110. The moving mechanism 113 can lower the probe 110 until the contact tip 108 at the tip of the probe 110 comes into contact with a surface below the probe 110, for example, the top surface 6 of the wafer 5 held on the holding surface 22 of the chuck table 20.

[0050] 2 and 3, scale 114 hangs down from the end of connecting member 103 and is disposed parallel to the Z-axis direction which is the extension direction of probe 110. Scale 114 is connected to probe 110 via connecting member 103 and moves together with probe 110 in the Z-axis direction.

[0051] The detection mechanism 115 is attached to an end of the case 101. The detection mechanism 115 includes a support plate 150 extending in the Z-axis direction, and a detection unit 151 disposed at the tip of the support plate 150. This detection unit 151 faces the graduations 140 of the scale 114, and reads the graduations 140. In this manner, the detection unit 151 can detect the height of the stylus 108 in contact with the lower surface of the probe 110 (for example, the upper surface 6 of the wafer 5) by reading the graduations 140 of the scale 114 which moves in the Z-axis direction together with the probe 110.

[0052] 1 includes a CPU, a memory, and the like, and controls each component of the grinding apparatus 1 to perform grinding processing on the wafer 5. The control unit 90 also includes an upper surface height measuring device origin storage unit 91, a calculation unit 92, and a holding surface height origin storage unit 93. The grinding processing of the wafer 5 in the grinding apparatus 1 controlled by the control unit 90 will be described below.

[0053] [Holding process] In this embodiment, first, an operator holds the wafer 5 on the holding surface 22 of the chuck table 20 shown in FIG.

[0054] [Measurement process] Next, the control unit 90 adjusts the position of the chuck table 20 using a moving member (not shown) so that the grinding wheel 77 is positioned at the center of rotation of the wafer 5 held on the holding surface 22 of the chuck table 20 .

[0055] Thereafter, the control unit 90 uses the grinding feed mechanism 60 to lower the grinding mechanism 70 so that the lower surface of the grinding wheel 77 comes into contact with the upper surface 6 of the wafer 5. At this time, the control unit 90 keeps the probe 110 of the upper surface height measuring device 80 in a state where it is hanging down from the case 101 by its own weight. In this state, the measuring element 108 of the probe 110 comes into contact with the top surface 6 of the wafer 5 before the bottom surface of the grinding wheel 77. Then, until the bottom surface of the grinding wheel 77 comes into contact with the top surface 6 of the wafer 5, the probe 110 rises relative to the case 101 as the grinding mechanism 70 descends, and the height of the measuring element 108 detected by the detection unit 151, i.e., the measurement value of the top surface height measuring device 80, changes. Then, by recognizing that the measurement value of the upper surface height measuring instrument 80 has stopped changing, the control unit 90 determines that the lower surface of the grinding wheel 77 has come into contact with the upper surface 6 of the wafer 5, and acquires as H0 the value of the height of the upper surface 6 of the wafer 5 measured by the upper surface height measuring instrument 80 at this time, i.e., the value of the height of the stylus 108 in contact with the upper surface 6 detected by the detection unit 151 (see FIG. 3). Thereafter, the control unit 90 uses the grinding feed mechanism 60 to raise the grinding mechanism 70.

[0056] In addition, the control unit 90 may acquire this H0 immediately before grinding of the wafer 5 by the grinding wheel 77 begins in the grinding process described below, i.e., when the lower surface of the descending grinding wheel 77 comes into contact with the upper surface 6 of the wafer 5.

[0057] [Grinding process] Next, the control unit 90 controls the spindle motor 73 of the grinding mechanism 70 to rotate the grinding wheel 77 together with the spindle 72. Furthermore, the control unit 90 causes the table rotation mechanism 50 to rotate the holding surface 22 of the chuck table 20 that holds the wafer 5.

[0058] Next, the control unit 90 uses the grinding feed mechanism 60 to lower the grinding mechanism 70 and bring it closer to the chuck table 20 so that the rotating grinding wheel 77 comes into contact with the upper surface 6 of the rotating wafer 5 .

[0059] Then, the control unit 90 acquires, as Z0, the value of the height of the grinding mechanism 70 recognized by the Z-axis encoder 65 when the lower surface of the grinding wheel 77 comes into contact with the wafer 5. Note that a virtual scale 200 indicating the height of the grinding mechanism 70 recognized by the Z-axis encoder 65 is shown in FIG. The control unit 90 may obtain this Z0 when obtaining H0 by the top surface height measuring device 80 in the measurement process.

[0060] Thereafter, the control unit 90 uses the grinding feed mechanism 60 to further lower the grinding mechanism 70, and grinds the upper surface 6 of the wafer 5 with the grinding wheel 77. Even during this grinding, the control unit 90 keeps the probe 110 of the upper surface height measuring device 80 in a state in which it hangs down from the case 101 by its own weight, thereby keeping the measuring element 108 in contact with the upper surface 6 of the wafer 5, which is on the same horizontal plane as the lower surface of the grinding wheel 77.

[0061] Then, the control unit 90 acquires as Z1 the height of the grinding mechanism 70 recognized by the Z-axis encoder 65, which changes downward (in the direction in which the grinding mechanism 70 descends) when the grinding mechanism 70 is lowered to grind the wafer 5, as shown in FIG. 4.

[0062] Furthermore, by grinding the wafer 5 with the grinding wheel 77, the grinding wheel 77 is worn down and its length is shortened. Therefore, the probe 108 of the top surface height measuring instrument 80 in contact with the top surface 6 of the wafer 5 being ground approaches the detection unit 151 of the top surface height measuring instrument 80 in the Z-axis direction by the amount of wear of the grinding wheel 77 (see FIG. 3). Therefore, the measurement value of the top surface height measuring instrument 80, i.e., the height value of the probe 108 detected by the detection unit 151, changes upward (becomes higher) by the amount of wear of the grinding wheel 77.

[0063] The control unit 90 acquires the measurement value of the upper surface height measuring device 80, which changes upward due to wear of the grinding wheel 77 while the wafer 5 is being ground, as H1, as shown in FIG.

[0064] Furthermore, the calculation unit 92 of the control unit 90 calculates a first calculation value during grinding using the following formula. |(Z0-Z1)|-|(H0-H1)|=First calculated value This first calculated value is a value obtained by subtracting the amount of wear |(H0-H1)| of the grinding wheel 77 in grinding from the amount of descent |(Z0-Z1)| of the grinding mechanism 70 in grinding, and corresponds to the amount of grinding of the wafer 5. The relationship between |(Z0-Z1)|, |(H0-H1)|, and the first calculated value (C1) is shown near the scale 200 in FIG.

[0065] Then, the control unit 90 grinds the wafer 5 with the grinding wheel 77 until the first calculation value calculated by the calculation unit 92 becomes equal to the preset grinding amount. That is, when the first calculation value becomes equal to the preset grinding amount, the control unit 90 determines that the thickness of the wafer 5 becomes the predetermined thickness, and causes the grinding feed mechanism 60 to raise the grinding mechanism 70, thereby completing the grinding.

[0066] As described above, in this embodiment, the grinding amount of the wafer 5 is obtained by subtracting the wear amount |(H0-H1)| of the grinding wheel 77 obtained using the top surface height measuring device 80 that rises and falls together with the grinding mechanism 70 from the descent amount |(Z0-Z1)| of the grinding mechanism 70 obtained using the Z-axis encoder 65 during grinding.

[0067] In this manner, in this embodiment, the grinding amount of the wafer 5 is measured using the Z-axis encoder 65 and the top surface height measuring device 80 that rises and falls together with the grinding mechanism 70. Therefore, it is not necessary to obtain the grinding amount of the wafer 5 only by the top surface height measuring device provided on the base 3 of the grinding device 1, as in the conventional method. Therefore, even if the thickness of the wafer 5 before grinding or the grinding amount of the wafer 5 exceeds the measurement range of the top surface height measuring device 80, the wafer 5 can be ground while measuring the grinding amount of the wafer 5 held by the chuck table 20.

[0068] Therefore, in this embodiment, even if the measurement range of the top surface height measuring device 80 is not long, it is possible to measure the grinding amount of a thick wafer 5 such as an ingot, and even if the wafer 5 is thin, it is possible to measure the grinding amount. Therefore, there is no need to provide an expensive measuring device with a long measurement range in order to grind a thick wafer 5. Therefore, it is possible to reduce the cost of the grinding device 1.

[0069] In this embodiment, an upper surface height measuring device 80 is provided on the grinding mechanism 70 by a mounting member 81. Therefore, the upper surface height measuring device 80 can measure the height of the upper surface 6 of the wafer 5 near the trajectory of the grinding wheel 77.

[0070] In this embodiment, when acquiring H0, which is a value measured by the upper surface height measuring device 80 of the height of the horizontal plane that is the same as the lower surface of the grinding wheel 77, the lower surface of the grinding wheel 77 is brought into contact with the upper surface 6 of the wafer 5. In this regard, when acquiring H0, as shown in FIG. 5, a setup block 7 having a predetermined thickness may be held on the upper surface 6 of the wafer 5. In this case, the control unit 90 acquires H0 as a value measured by the upper surface height measuring device 80 of the height of the upper surface 8 of the setup block 7 that is the same as the lower surface of the grinding wheel 77. In this case, H0 is also a value according to the length of the grinding wheel 77 before it is worn down by grinding, similar to H0 obtained by contacting the lower surface of the grinding wheel 77 with the upper surface 6 of the wafer 5. Therefore, as in the above-mentioned embodiment, the wear amount |(H0-H1)| of the grinding wheel 77 can be measured well. The setup block 7 may be placed on the holding surface 22.

[0071] Furthermore, the thickness of the setup block 7 is accurately recognized by the control unit 90. Therefore, the control unit 90 can grasp the lowering amount (grinding feed amount) of the grinding mechanism 70 for grinding the wafer 5 to a predetermined thickness based on the height of the grinding mechanism 70 when the lower surface of the grinding wheel 77 contacts the upper surface 8 of the setup block 7 and the thickness of the setup block 7.

[0072] Furthermore, the control unit 90 may acquire H0, which is a value measured by the top surface height measuring device 80 of the height of the same horizontal plane as the bottom surface of the grinding wheel 77 (for example, the top surface 6 of the wafer 5 or the top surface 8 of the setup block 7), and then store this H0 in the top surface height measuring device origin storage unit 91. This allows the control unit 90 to repeatedly use H0, which is data regarding the length of the grinding wheel 77 before it becomes worn out.

[0073] In addition, when grinding the wafer 5 held by the holding surface 22 of the chuck table 20, the control unit 90 uses the grinding feed mechanism 60 to lower the grinding mechanism 70 from above the wafer 5, and when the measurement value of the top surface height measuring device 80 matches the H0 stored in the top surface height measuring device origin memory unit 91, it can determine that the bottom surface of the grinding wheel 77 has come into contact with the top surface 6 of the wafer 5.

[0074] That is, as described above, when the grinding mechanism 70 is lowered during grinding, the measuring piece 108 of the probe 110, which is hanging down from the case 101 due to its own weight, comes into contact with the upper surface 6 of the wafer 5 before the lower surface of the grinding wheel 77. Then, as the grinding mechanism 70 is lowered, the probe 110 in contact with the upper surface 6 rises relative to the case 101, and the height of the measuring piece 108 detected by the detection unit 151, i.e., the measurement value of the upper surface height measuring device 80, approaches H0. Therefore, the control unit 90 can determine that the lower surface of the grinding wheel 77 has come into contact with the upper surface 6 of the wafer 5 by recognizing that the measurement value of the upper surface height measuring device 80 has become H0.

[0075] In this configuration, the control unit 90 can easily obtain the timing when the bottom surface of the grinding wheel 77 comes into contact with the wafer 5. Therefore, the control unit 90 can easily obtain, for example, Z0, which is the height of the grinding wheel 77 recognized by the Z-axis encoder 65 when the bottom surface of the grinding wheel 77 comes into contact with the wafer 5.

[0076] In this embodiment, in order to obtain the grinding amount of the wafer 5, the sinking amount of the chuck table 20 may be used in addition to the lowering amount of the grinding mechanism 70 and the wear amount of the grinding wheel 77. In this case, a holding surface height measuring device 83 is used. The holding surface height measuring device 83 is configured to measure the height of the frame surface 24 of the frame 23 on the chuck table 20 , thereby measuring the height of the holding surface 22 which is flush with the frame surface 24 .

[0077] In this case, as shown in FIG. 6, when no vertical load is applied to the holding surface 22 of the chuck table 20, for example, after the holding process in which the wafer 5 is held on the holding surface 22 of the chuck table 20, and before the grinding wheel 77 comes into contact with the wafer 5 in the grinding process, the control unit 90 measures the height of the holding surface 22 using the holding surface height measuring device 83, obtains this measurement value as P0, and stores it, for example, in the holding surface height origin memory unit 93.

[0078] Thereafter, in the grinding process, the control unit 90 uses the grinding feed mechanism 60 to lower the grinding mechanism 70, and keeps the measuring element 108 of the probe 110 of the holding surface height measuring device 83 in contact with the frame surface 24 when grinding the upper surface 6 of the wafer 5 with the grinding wheel 77.

[0079] Here, when the wafer 5 is being ground, the holding surface 22 is pressed downward by the grinding wheel 77, causing the chuck table 20 to sink, and therefore the height of the holding surface 22 measured by the holding surface height measuring instrument 83 becomes lower. Then, when the wafer 5 is being ground, the control unit 90 acquires the above-mentioned H1 and Z1, and also acquires as P1 the measurement value of the holding surface height measuring instrument 83 that changes downward due to the sinking of the chuck table 20.

[0080] Moreover, the calculation unit 92 of the control unit 90 calculates a second calculation value during grinding using the following formula. |(Z0-Z1)|-|(H0-H1)|-|(P1-P0)|=Second calculated value This second calculated value is a value obtained by subtracting the wear amount |(H0-H1)| of the grinding wheel 77 and the sinking amount |(P1-P0)| of the chuck table 20 during grinding from the lowering amount |(Z0-Z1)| of the grinding mechanism 70 during grinding, and corresponds to the grinding amount of the wafer 5. The relationship between |(Z0-Z1)|, |(H0-H1)|, |(P1-P0)|, and the second calculated value (C2) is shown near the scale 200 in FIG.

[0081] Then, the control unit 90 grinds the wafer 5 with the grinding wheel 77 until the second calculation value calculated by the calculation unit 92 becomes equal to the preset grinding amount. That is, when the second calculation value becomes equal to the preset grinding amount, the control unit 90 determines that the thickness of the wafer 5 becomes the predetermined thickness, and causes the grinding feed mechanism 60 to raise the grinding mechanism 70, thereby completing the grinding.

[0082] In this configuration, the amount of grinding of the wafer 5 is measured using the amount of sinking of the chuck table 20 in addition to the amount of descent of the grinding mechanism 70 and the amount of wear of the grinding wheel 77. Therefore, it is possible to measure the amount of grinding of the wafer 5 more accurately.

[0083] In this embodiment, the upper surface height measuring device 80 is provided in the grinding mechanism 70 and is configured to measure the height of the same horizontal plane as the grinding wheel 77 using the probe 110. In this regard, the upper surface height measuring device 80 is configured to move up and down in the Z-axis direction together with the grinding mechanism 70, and can measure the height of the same horizontal plane as the lower surface of the grinding wheel 77, and may be configured without the probe 110 as long as the measured value changes due to wear of the grinding wheel 77. For example, the upper surface height measuring device 80 may be a laser type (or sonic type) distance measuring device provided in the grinding mechanism 70 and measuring the height of the same horizontal plane in a non-contact manner. This distance measuring device, for example, irradiates the same horizontal plane with a laser beam (sound wave) and measures the height based on the reflected light (reflected wave) from the same horizontal plane. [Explanation of symbols]

[0084] 1: grinding device, 3: base, 5: wafer, 6: upper surface, 7: Setup block, 8: Top surface, 11: Column, 20: Chuck table, 21: porous member, 22: holding surface, 23: frame, 24: frame surface, 40: tilt adjustment mechanism, 41: internal base, 42: tilt adjustment shaft, 43: fixed shaft, 45: annular member, 46: connecting portion, 50: table rotation mechanism, 55: Table base, 60: Grinding feed mechanism, 61: Z-axis guide rail, 62: Z-axis ball screw, 63: Z-axis moving table, 64: Z-axis motor, 65: Z-axis encoder, 67: slide member, 68: nut portion, 70: grinding mechanism, 71: spindle housing, 72: spindle, 73: spindle motor, 74: wheel mount, 75: grinding wheel, 76: Wheel base, 77: Grinding wheel, 79: Holder, 80: upper surface height measuring device, 81: mounting member, 83: holding surface height measuring device, 90: control unit, 91: upper surface height measuring device origin storage unit, 92: calculation unit, 93: holding surface height origin storage unit, 101: case, 102: mounting surface, 103: connecting member, 108: measuring element, 110: probe, 111: side surface, 112: housing, 113: moving mechanism, 114: scale, 115: detection mechanism, 116: exhaust port, 117: throttle valve, 120: cylinder, 121: support surface, 122: spout, 123: inlet, 124: flow path, 125: upper exhaust port, 126: lower exhaust port, 130: cylinder, 131: piston, 132: inlet, 133: inlet, 140: scale, 150: support plate, 151: detection unit, 200: scale, 240: suction source, 241: air supply source, 242: water supply source, 243: flow path, 270: suction valve, 271: air valve, 272: water valve, 502: Arrow, 521: Motor, 522: Drive pulley, 523: Endless belt, 524: Driven pulley, 525: Rotary joint, 761: Processing water channel

Claims

1. A grinding device comprising: a chuck table whose holding surface holds a workpiece; a grinding mechanism that grinds an upper surface of the workpiece held by the holding surface with a grinding wheel; a grinding feed mechanism that raises and lowers the grinding mechanism in a direction perpendicular to the holding surface; a height position recognition unit that recognizes a height position of the grinding mechanism raised and lowered by the grinding feed mechanism; an upper surface height measuring device that measures the height of the upper surface of the workpiece held by the holding surface; and a control unit, the upper surface height measuring device is configured to be raised and lowered together with the grinding mechanism in a direction perpendicular to the holding surface by the grinding feed mechanism; The control unit The height of the horizontal plane that is the same as the lower surface of the grinding wheel, as measured by the upper surface height measuring device, is defined as H0. The height of the grinding mechanism recognized by the height position recognition unit when the lower surface of the grinding wheel comes into contact with the workpiece is defined as Z0, The height of the grinding mechanism, which changes downward when the grinding mechanism is lowered to grind the workpiece and is recognized by the height position recognition unit, is defined as Z1. The measurement value of the upper surface height measuring device, which changes due to wear of the grinding wheel when the workpiece is being ground, is defined as H1, A calculation unit is provided that calculates a first calculation value by the following formula during grinding, |(Z0-Z1)|-|(H0-H1)|=first calculated value The grinding apparatus grinds the workpiece until the first calculated value calculated by the calculation unit becomes equal to a preset grinding amount.

2. The control unit a top surface height measuring device origin storage unit for storing a value (H0) of the height of a horizontal plane that is the same as the bottom surface of the grinding wheel, the value being measured by the top surface height measuring device; the grinding mechanism is lowered from above the workpiece held by the holding surface using the grinding feed mechanism, and when the measurement value of the top surface height measuring device coincides with the value (H0) stored in the top surface height measuring device origin memory unit, it is determined that the bottom surface of the grinding wheel has come into contact with the top surface of the workpiece.

2. The grinding apparatus according to claim 1.

3. a holding surface height measuring device that is disposed on a base for arranging the chuck table and the grinding mechanism and measures the height of the holding surface; a holding surface height origin storage unit that stores a value (P0) measured by the holding surface height measuring device when no vertical load is applied to the holding surface, The control unit sets a measurement value of the holding surface height measuring device, which changes downward due to sinking of the chuck table while the workpiece is being ground, as P1, The calculation unit calculates a second calculation value during grinding by the following formula, |(Z0-Z1)|-|(H0-H1)|-|(P1-P0)|=second calculated value The control unit grinds the workpiece until the second calculated value becomes equal to a preset grinding amount.

2. The grinding apparatus according to claim 1.

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