Installation method

Abstract

[Problem] This invention enables installation in a short time without the need for additional sensors. [Solution] The lifting mechanism descends from above the wafer held by the holding surface and memorizes the height of the grinding mechanism when the lower surface of the grinding stone contacts the upper surface of the wafer. Then, based on this height, the height of the grinding mechanism when the lower surface of the grinding stone contacts the holding surface, i.e., the origin height, is determined. Thus, installation to determine the origin height of the grinding mechanism can be performed without using a mounting block. Therefore, installation can be carried out in a short time.

Description

[Technical Field]

[0001] This invention relates to an installation method. [Previous Technology]

[0002] As disclosed in Patent Document 1, the grinding apparatus for grinding the wafer held by the holding surface of the chuck stage with a grinding stone is installed such that the height of the grinding mechanism on which the grinding stone is mounted is identified when the lower surface of the grinding stone is in contact with the holding surface.

[0003] In this type of installation, as disclosed in Patent Documents 2 and 3, there are cases where sensors are used and cases where setup blocks are used. [Preferred Art Documents] [Patent Documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2001-001261 ​​[Patent Document 2] Japanese Patent Application Publication No. 2012-135853 [Patent Document 3] Japanese Patent Application Publication No. 2020-199597 [Summary of the Invention]

[0005] [Problems to be Solved by the Invention] However, in the installation using mounting blocks, the height of the grinding mechanism needs to be changed to confirm whether the mounting block should be placed, which is time-consuming. Furthermore, in the installation using sensors, the sensors are expensive.

[0006] Therefore, the object of the present invention is to provide an installation method that can be installed in a shorter time without the need for additional sensors.

[0007] [Technical Means for Solving the Problem] According to the present invention, an installation method is provided that uses a grinding apparatus, the grinding apparatus comprising: a chuck table holding a plate-shaped object on its holding surface; a grinding mechanism grinding the plate-shaped object held on the holding surface with a grinding stone; a lifting mechanism moving the grinding mechanism in a direction perpendicular to the holding surface; and a height recognition unit recognizing the height of the grinding mechanism after it has been moved by the lifting mechanism. The installation method moves the grinding mechanism using the lifting mechanism and memorizes the height of the grinding mechanism when the lower surface of the grinding stone has contacted the holding surface, wherein the grinding mechanism includes a contact detection... The contact detection unit detects whether the lower surface of the grinding stone has contacted the upper surface of the plate. The installation method includes: a holding step in which the retaining surface of the chuck table holds the plate with the elastic part disposed between the central portion of the lower surface of the plate and the retaining surface; and a memory step in which the grinding mechanism on which the grinding stone is mounted is lowered from above the plate held by the retaining surface, and the height of the grinding mechanism is memorized when the contact detection unit detects that the lower surface of the grinding stone has contacted the upper surface of the plate held by the retaining surface. Preferably, the grinding apparatus further includes an upper surface height measuring device, which measures the upper surface height of the plate held by the holding surface. The upper surface height measuring device is configured to move together with the grinding mechanism in a direction perpendicular to the holding surface via the lifting mechanism. The contact detection unit begins measuring the upper surface height of the plate by the upper surface height measuring device before the grinding mechanism is lowered and the lower surface of the grinding stone contacts the plate. As the grinding mechanism continues to lower and the lower surface of the grinding stone presses against the upper surface of the plate, the lower surface of the grinding stone is detected to be in contact with the upper surface of the plate by identifying that the change in the measurement value of the upper surface height measuring device is no longer a change relative to the change in the height of the grinding mechanism. Preferably, the grinding mechanism includes a rotation detection unit that detects the rotational speed of the grinding stone. The contact detection unit detects that the lower surface of the grinding stone has contacted the upper surface of the plate by detecting a decrease in the rotational speed of the grinding stone. In this mounting method, the elastic portion in the holding step can also be a cavity formed between the holding surface and the central portion of the lower surface of the plate.

[0008] [Effect of the Invention] In this installation method, during the memory step, the lifting mechanism is lowered from above the plate held by the holding surface, and the height of the grinding mechanism when the lower surface of the grinding stone is in contact with the upper surface of the plate is memorized. Then, based on this height, the height of the grinding mechanism when the lower surface of the grinding stone is in contact with the holding surface, i.e., the origin height, is determined.

[0009] Thus, in this installation method, for example, the origin height of the grinding mechanism can be determined without using a mounting block after replacing the grinding stone. Therefore, installation can be performed quickly. Furthermore, since no mounting sensor is used, installation can be performed using a low-cost configuration. Moreover, in the holding step, an elastic portion is provided between the central portion of the lower surface of the plate and the holding surface. Therefore, when the lower surface of the grinding stone contacts the upper surface of the plate, the elastic portion deforms to mitigate the impact of contact, thus preventing damage to the lower surface of the grinding stone.

Implementation Method

[0011] The grinding apparatus 1 of this embodiment shown in FIG1 is an apparatus for grinding a wafer 5, which is an example of a plate-shaped object. The wafer 5 is, for example, a circular semiconductor wafer. The upper surface 6 of the wafer 5 becomes the surface to be ground.

[0012] In this embodiment, the wafer 5 is processed in the form of a frame unit 9. The frame unit 9 is formed by integrating the ring frame 7 with the wafer 5 using an adhesive film 8. The ring frame 7 has an opening that can accommodate the wafer 5, and the wafer 5 is positioned in the opening of the ring frame 7. In this embodiment, the wafer 5 is ground in the grinding apparatus 1 in this frame unit 9 state.

[0013] As shown in Figure 1, the grinding device 1 includes: a cuboid base 10, an upwardly extending column 11, and a control unit 3 for controlling each component of the grinding device 1.

[0014] An opening 13 is provided on the upper surface of the base 10. Furthermore, a wafer holding mechanism 30 is disposed within the opening 13. The wafer holding mechanism 30 includes: a chuck stage 20, whose holding surface 22 holds the wafer 5; a worktable base 55, which supports the chuck stage 20; a worktable rotation mechanism 50, which rotates the chuck stage 20 and the worktable base 55; and a tilt adjustment mechanism 40, which adjusts the tilt of the chuck stage 20.

[0015] As shown in Figures 1 and 2, the chuck stage 20 includes: a porous member 21 serving as a wafer holding portion; and a frame 23 that houses the porous member 21 with its upper surface exposed. The upper surface of the porous member 21 is a holding surface 22 that attracts and holds the wafer 5. The holding surface 22 attracts and holds the wafer 5 by communicating with an attraction source 240 described later. The upper surface of the frame 23, i.e., the frame surface 24, is formed flush with the holding surface 22.

[0016] Furthermore, the frame 23 includes four clamps 31 as frame holding parts, which are used to hold the ring frame 7 of the frame unit 9. In addition, the holding surface 22 is configured to hold the wafer 5 above the upper surface of the ring frame 7 held by the clamps 31.

[0017] A worktable base 55 supporting the chuck table 20 is provided below the chuck table 20. Then, a worktable rotation mechanism 50 supporting the worktable base 55 in a rotatable manner is provided below the worktable base 55.

[0018] As shown in FIG2, the worktable rotation mechanism 50 includes: a motor 521, a drive pulley 522 mounted on the motor 521, a driven pulley 524 connected to the drive pulley 522 via an annular belt 523, and a rotary joint 525 disposed below the driven pulley 524. The driven pulley 524 is supported on the narrow-diameter portion of the lower part of the worktable base 55.

[0019] In the table rotation mechanism 50, the motor 521 drives the drive pulley 522 to rotate, thereby rotating the annular belt 523 and the driven pulley 524. As a result, the table base 55 and the chuck table 20 rotate as indicated by arrow 502.

[0020] Furthermore, a tilt adjustment mechanism 40 for adjusting the tilt of the chuck table 20 is provided around the worktable base 55.

[0021] The tilt adjustment mechanism 40 includes: an inner base 41 disposed below the chuck table 20, a tilt adjustment shaft 42, a fixing shaft 43 fixed to the inner base 41, and an annular member 45.

[0022] The annular member 45 supports the worktable base 55 in a rotatable manner by means of a connecting part 46 including a bearing and surrounding the worktable base 55.

[0023] The upper end of the fixed shaft 43 is fixed to the lower surface of the annular member 45, and the lower end is fixed to the upper surface of the inner base 41.

[0024] The tilt adjustment shaft 42 is disposed between the inner base 41 and the annular member 45, and a portion of the annular member 45 can be moved up and down along the Z-axis. This adjusts the tilt of the chuck table 20.

[0025] Furthermore, in the tilt adjustment mechanism 40, the annular member 45 is supported on the inner base 41 at three locations, with tilt adjustment shafts 42 arranged at two or one of the three locations, and fixed shafts 43 provided at the other or two locations. However, the tilt adjustment mechanism 40 may also not have fixed shafts 43, but instead have tilt adjustment shafts 42 arranged at all three locations mentioned above.

[0026] Furthermore, a flow path 243 is connected to the chuck table 20, and the suction source 240, the air supply source 241 and the water supply source 242 are connected to this flow path 243 through the suction valve 270, the air valve 271 and the water valve 272 respectively.

[0027] Thus, in the grinding apparatus 1, air or water can be supplied to the holding surface 22 of the chuck table 20, and an attractive force from the attraction source 240 can be applied to the holding surface 22.

[0028] As shown in Figure 1, a cover plate 39 is provided around the chuck stage 20, and the cover plate 39 moves together with the chuck stage 20 along the Y-axis. Furthermore, a serpentine cover 12 that extends and retracts along the Y-axis is connected to the cover plate 39. Then, a Y-axis moving mechanism 90 is arranged below the wafer holding mechanism 30.

[0029] The Y-axis moving mechanism 90 moves the wafer holding mechanism 30, which includes the chuck stage 20, relative to the grinding mechanism 70 in a direction parallel to the holding surface 22, i.e., in the Y-axis direction. In this embodiment, the Y-axis moving mechanism 90 is configured to move the wafer holding mechanism 30 in the Y-axis direction relative to the grinding mechanism 70.

[0030] The Y-axis moving mechanism 90 includes: a pair of Y-axis guide rails 92 parallel to the Y-axis direction; a Y-axis moving stage 95 sliding on the Y-axis guide rails 92; a Y-axis ball screw 93 parallel to the Y-axis guide rails 92; a Y-axis motor 94 connected to the Y-axis ball screw 93; a Y-axis encoder 96 for detecting the rotation angle of the Y-axis motor 94; and a holding stage 91 for holding these components.

[0031] The Y-axis moving stage 95 is slidably mounted on the Y-axis guide rail 92. A nut (not shown) is fixed to the lower surface of the Y-axis moving stage 95. A Y-axis ball screw 93 is screwed into this nut. The Y-axis motor 94 is connected to one end of the Y-axis ball screw 93.

[0032] In the Y-axis moving mechanism 90, the Y-axis ball screw 93 is rotated by the Y-axis motor 94, causing the Y-axis moving stage 95 to move along the Y-axis guide rail 92 in the Y-axis direction. A wafer holding mechanism 30 is mounted on the Y-axis moving stage 95. Therefore, as the Y-axis moving stage 95 moves in the Y-axis direction, the wafer holding mechanism 30, including the chuck stage 20, moves in the Y-axis direction.

[0033] In this embodiment, the wafer holding mechanism 30 is moved along the Y-axis direction between the wafer placement area for holding the wafer 5 on the -Y direction side of the holding surface 22 and the grinding area for grinding the wafer 5 on the +Y direction side by means of the Y-axis direction moving mechanism 90.

[0034] Furthermore, as shown in Figures 1 and 2, a column 11 is erected on the rear (+Y direction side) of the base 10. A grinding mechanism 70 for grinding the wafer 5 and a lifting mechanism 60 are provided on the column 11.

[0035] The lifting mechanism 60 moves the grinding mechanism 70 in a direction perpendicular to the holding surface 22 of the chuck table 20, i.e., in the Z-axis direction (grinding feed direction). The lifting mechanism 60 includes: a pair of Z-axis guide rails 61 parallel to the Z-axis direction; a Z-axis moving stage 63 sliding on the Z-axis guide rails 61; a Z-axis ball screw 62 parallel to the Z-axis guide rails 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 mounted on the Z-axis moving stage 63.

[0036] The Z-axis moving stage 63 is slidably mounted on the Z-axis guide rail 61 via a sliding member 67 (refer to Figure 2). A nut portion 68 (refer to Figure 2) is fixed to the Z-axis moving stage 63. A Z-axis ball screw 62 is screwed into this nut portion 68. The Z-axis motor 64 is connected to one end of the Z-axis ball screw 62.

[0037] In the lifting mechanism 60, the Z-axis motor 64 rotates the Z-axis ball screw 62, thereby 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. Consequently, the grinding mechanism 70 mounted on the Z-axis moving table 63 also moves up and down in the Z-axis direction together with the Z-axis moving table 63.

[0038] Furthermore, the Z-axis encoder 65 functions as a height recognition unit, identifying the height of the grinding mechanism 70, which has moved via the lifting mechanism 60, by detecting the rotation angle of the Z-axis motor 64. Additionally, the Z-axis encoder 65 may, for example, determine the height of the nut portion 68 of the lifting mechanism 60, which moves in the Z-axis direction together with the grinding mechanism 70, and use this height as the height of the grinding mechanism 70.

[0039] The grinding mechanism 70 grinds the wafer 5 held on the holding surface 22 of the chuck stage 20 by means of the grinding stone 77. As shown in Figures 1 and 2, the grinding mechanism 70 includes: a holding seat 79 fixed to the Z-axis moving stage 63; a spindle housing 71 held in the holding seat 79; a spindle 72 for rotating the grinding stone 77; a spindle motor 73 for rotating and driving the spindle 72; a rotation detection unit 78 for detecting the rotational speed of the grinding stone 77; a wheel frame 74 mounted on the lower end of the spindle 72; and a grinding wheel 75 supported by the wheel frame 74.

[0040] The spindle 72 extends along the Z-axis direction orthogonal to the holding surface 22 of the chuck table 20, and is supported on the spindle housing 71 in a manner that allows it to rotate around the axis along the extension direction. The spindle motor 73 shown in FIG1 is connected to the upper end of the spindle 72 and rotates the spindle 72.

[0041] The wheel carrier 74 is formed in the shape of a circular plate and is fixed to the lower end of the spindle 72. The wheel carrier 74 supports the grinding wheel 75.

[0042] The grinding wheel 75 is formed with an outer diameter that is approximately the same as the outer diameter of the wheel carrier 74. The grinding wheel 75 includes an annular wheel base 76 formed of a metal material. A processing water path 761 is formed inside the wheel base 76, which is used to supply processing water from a water source not shown to the grinding stone 77 (refer to FIG. 2).

[0043] A plurality of grinding stones 77 arranged in a ring are fixed on the lower surface of the wheel base 76, covering the entire circumference. The grinding stones 77 rotate together with the spindle 72 with their center as the axis and by the spindle motor 73, grinding the upper surface 6 of the wafer 5 held on the chuck stage 20.

[0044] Furthermore, the grinding apparatus 1 includes an upper surface height measuring device 80, which measures the upper surface height of the wafer 5 held by the holding surface 22 of the chuck stage 20. The upper surface height measuring device 80 is mounted on the holding seat 79 of the grinding mechanism 70 by means of a mounting member 81, thereby being disposed in the grinding mechanism 70. In this way, the upper surface height measuring device 80 moves together with the grinding mechanism 70 in a direction perpendicular to the holding surface 22, i.e., in the Z-axis direction, by means of a lifting mechanism 60.

[0045] Furthermore, the upper surface height measuring device 80 can be configured to move together with the grinding mechanism 70 in the Z-axis direction via the lifting mechanism 60. For example, it can also be a part of the lifting mechanism 60 that moves up and down together with the grinding mechanism 70.

[0046] Furthermore, the grinding apparatus 1 includes a contact or non-contact retaining surface height measuring device 83, which is used to measure the height of the retaining surface 22 of the chuck table 20. The retaining surface height measuring device 83 is disposed on the side of the opening 13 of the base 10.

[0047] Here, the configuration of the upper surface height measuring device 80 will be described. The upper surface height measuring device 80 shown in FIG3 and FIG4 includes: a probe 110, which contacts the upper surface 6 of the wafer 5 with its front end; a housing 112, which serves as a guide and supports the probe 110 in a manner that allows it to be raised and lowered freely by its own weight; and a scale 114, which is used to read the height position of the probe 110.

[0048] In this embodiment, the upper surface height measuring device 80 further includes: a moving mechanism 113 that moves the probe 110 along the Z-axis direction; a detection mechanism 115 that reads the scale 140 of the ruler 114; an exhaust port 116 and a throttle valve 117 for exhausting air; and a housing 101 that serves as a shell.

[0049] The probe 110 extends in a direction perpendicular to the holding surface 22, that is, in the Z-axis direction. The upper end of the probe 110 is connected to the connecting member 103.

[0050] The housing 101 is supported from above by the mounting member 81 shown in Figures 1 and 2. As shown in Figures 3 and 4, the probe 110 is formed into a quadrangular prism and penetrates the housing 101, with the front end of the probe 110 protruding downward from the lower surface of the housing 101.

[0051] The outer shell 112 surrounds the side 111 of the probe 110, and supports the probe 110 in a non-contact manner in a way that allows it to move in the Z-axis direction perpendicular to the holding surface 22.

[0052] That is, the outer casing 112 has a cylindrical portion 120 for receiving the probe 110. The cylindrical portion 120 is disposed on the mounting surface 102 on the inner side of the housing 101. A four-cornered hole with a cross-section for receiving the probe 110 is formed in the cylindrical portion 120 in a manner corresponding to the shape of the probe 110. The cylindrical portion 120 is configured to allow the probe 110 to be inserted through this hole and to support the probe 110 around its perimeter without contact.

[0053] Furthermore, the cylindrical portion 120 includes 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 at equal intervals from the side surface 111 of the probe 110.

[0054] Furthermore, as shown in FIG4, the cylindrical portion 120 includes: an inlet 123 connected to an air supply source (not shown); and a flow path 124 that connects the inlet 123 to each nozzle 122.

[0055] In the housing 112, with the support surface 121 of the cylindrical portion 120 facing the side surface 111 of the probe 110, air supplied to the inlet 123 is blown through the flow path 124 and the nozzle 122 of the support surface 121 onto the side surface 111 of the probe 110. In this way, the housing 112 can support the probe 110 even when there is air between the side surface 111 of the probe 110 and the support surface 121.

[0056] Furthermore, in the housing 112, air flowing into the cylinder 120 is discharged 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 that it can move in the Z-axis direction.

[0057] The exhaust port 116 is used to exhaust air from the outer casing 112 into the housing 101 to the outside of the housing 101. The throttle valve 117 connected to the exhaust port 116 adjusts the exhaust volume to regulate the pressure inside the housing 101, and adjusts the pushing pressure of the probe 110 against the upper surface 6 of the wafer 5.

[0058] The moving mechanism 113 is disposed near the probe 110 on the mounting surface 102 of the housing 101. The moving mechanism 113 includes a cylinder 130 and a piston 131. The piston 131 moves within the cylinder 130 in the Z-axis direction, which is parallel to the axial direction of the probe 110.

[0059] Furthermore, the moving mechanism 113 has inlets 132 and 133 in the cylinder 130 for allowing air to flow into its interior. The moving mechanism 113 with this structure can move the probe 110 in the Z-axis direction by moving the piston 131 linearly in the Z-axis direction through the connecting member 103.

[0060] That is, when the probe 110 is raised in the +Z direction by the moving mechanism 113, air from an air supply source (not shown) is supplied into the cylinder 130 through the inlet 132. Hereby, inside the cylinder 130, the piston 131 rises. Then, the piston 131 contacts the connecting member 103 and raises the connecting member 103, thereby raising the probe 110 connected to the connecting member 103.

[0061] 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 to the cylinder 130 through the inlet 133. This causes the piston 131 to descend inside the cylinder 130. Consequently, the probe 110 descends due to its own weight and the connecting member 103 connected to it.

[0062] Furthermore, the moving mechanism 113 adjusts the descent speed of the piston 131 by adjusting the inflow rate of air from the inlet 133, thereby limiting the descent speed of the probe 110. Then, the moving mechanism 113 can lower the probe 110 until the tip of the probe 110 contacts the surface below the probe 110, for example, until it contacts the upper surface 6 of the wafer 5 held by the holding surface 22 of the chuck stage 20.

[0063] As shown in Figures 3 and 4, the scale 114 hangs down from the end of the connecting member 103 and is configured to be parallel to the extension direction of the probe 110, i.e., the Z-axis direction. The scale 114 is connected to the probe 110 through the connecting member 103 and moves together with the probe 110 in the Z-axis direction.

[0064] The detection mechanism 115 is mounted at the end of the housing 101. The detection mechanism 115 includes: a support plate 150 extending in the Z-axis direction; and a detection unit 151 disposed at the front end of the support plate 150. This detection unit 151 faces the scale 140 of the scale 114 and reads this scale 140. Thus, the detection unit 151 can detect the height of the probe 110 in contact with the upper surface 6 of the wafer 5 by reading the scale 140 of the scale 114 that moves together with the probe 110 in the Z-axis direction.

[0065] The control unit 3 shown in Figures 1 and 2 includes a CPU and memory, and controls the components of the grinding apparatus 1 to install the grinding mechanism 70 and perform grinding processing on the wafer 5. Furthermore, the control unit 3 functions as a contact detection unit, detecting whether the lower surface of the grinding stone 77 in the grinding mechanism 70 is in contact with the upper surface 6 of the wafer 5 held by the holding surface 22 of the chuck stage 20. Additionally, a memory unit 4 is connected to the control unit 3, which stores measurements such as the height of the grinding mechanism 70.

[0066] The following describes the installation method of the grinding mechanism 70. This installation method is performed, for example, after replacing the grinding stone 77. In this installation method, the grinding mechanism 70 is moved by the lifting mechanism 60, and the height of the grinding mechanism 70 when the lower surface of the grinding stone 77 is in contact with the holding surface 22 of the chuck table 20 is remembered.

[0067] [Holding Step] In this step, the holding surface 22 holds the wafer 5 such that the elastic part is disposed between the central portion of the lower surface of the plate-like object, i.e., the wafer 5, and the holding surface 22 of the chuck stage 20.

[0068] Specifically, firstly, as shown in Figure 2, the operator places the wafer 5 of the frame unit 9 on the holding surface 22 of the chuck stage 20 through the adhesive film 8, and supports the ring frame 7 of the frame unit 9 by means of the clamp 31. In this way, the frame unit 9 containing the wafer 5 is held by the chuck stage 20.

[0069] Next, the control unit 3 uses the Y-axis direction moving mechanism 90 shown in FIG1 to adjust the position of the chuck stage 20 in such a way that the grinding stone 77 is positioned at the center of the wafer 5 held by the holding surface 22 of the chuck stage 20.

[0070] Subsequently, the control unit 3 uses the lifting mechanism 60 to lower the grinding mechanism 70, which is equipped with the grinding stone 77, and the upper surface height measuring device 80 from above the wafer 5 held by the holding surface 22. At this time, the control unit 3 first sets the probe 110 of the upper surface height measuring device 80 to a state in which it hangs down from the housing 101 by its own weight.

[0071] Thus, if the probe 110 is made to hang down from the housing 101 by its own weight, and the grinding mechanism 70 and the upper surface height measuring device 80 are lowered, as shown in FIG5, the tip of the probe 110 will contact the upper surface 6 of the wafer 5 first, compared to the lower surface of the grinding stone 77.

[0072] If the grinding mechanism 70 and the upper surface height measuring device 80 are lowered, and the tip of the probe 110 contacts the upper surface 6 of the wafer 5, the probe 110 rises in the +Z direction relative to the housing 101 (refer to FIG. 4), and the change in the height of the probe 110 in the +Z direction is detected by the detection unit 151. The control unit 3 detects that the tip of the probe 110 has contacted the upper surface 6 of the wafer 5 by detecting the change in the height of the probe 110 in the +Z direction, stops the descent of the grinding mechanism 70 and the upper surface height measuring device 80 performed by the lifting mechanism 60, and obtains the height of the probe 110 detected by the detection unit 151 of the upper surface height measuring device 80 as the first measurement value A1.

[0073] Next, the control unit 3 controls the air valve 271 (refer to FIG. 2) to connect the air supply source 241 to the holding surface 22 of the chuck stage 20, thereby initiating air blowing from the holding surface 22. This blows air from the holding surface 22 of the chuck stage 20 onto the adhesive film 8 of the frame unit 9 facing the holding surface 22. As a result, the adhesive film 8 and the wafer 5 are lifted in the +Z direction, and as shown in FIG. 6, a cavity 210, serving as an elastic portion, is formed between the holding surface 22 and the central portion 51 of the lower surface of the wafer 5. Alternatively, water can be sprayed from the holding surface 22 to form an elastic portion. Thus, during the holding step, as shown in FIGS. 6 and 7, the holding surface 22 holds the wafer 5 by forming and arranging the cavity 210, serving as an elastic portion, between the central portion 51 of the lower surface of the wafer 5 and the holding surface 22.

[0074] Furthermore, by forming the cavity 210, the probe 110, which is in contact with the upper surface 6 of the wafer 5, rises in the +Z direction as shown by arrow 400 in FIG6. The control unit 3 detects the height of the risen probe 110 by means of the detection unit 151 of the upper surface height measuring device 80, and obtains the height of the risen probe 110 as the second measurement value A2. Furthermore, the control unit 3 calculates the difference (|A1-A2|) between the first measurement value A1 and the second measurement value A2, and identifies this difference as the thickness V1 of the cavity 210. In addition, when forming the cavity 210 and raising the probe 110, the lower surface of the grinding stone 77 is not in contact with the upper surface 6 of the wafer 5, and the lower end of the probe 110 is lower than the lower surface of the grinding stone 77, so that the probe 110 hangs down from the housing 101.

[0075] [Memory Step] Subsequently, in order to make the lower surface of the grinding stone 77 contact the upper surface 6 of the wafer 5, the control unit 3 uses the lifting mechanism 60 to restart the descent of the grinding mechanism 70 from above the wafer 5 held by the holding surface 22.

[0076] Furthermore, as described above, the tip of the probe 110 contacts the upper surface 6 of the wafer 5 earlier than the lower surface of the grinding stone 77. Therefore, the control unit 3 begins measuring the upper surface height of the upper surface 6 of the wafer 5 by the upper surface height measuring device 80 before the lower surface of the grinding stone 77 contacts the wafer 5.

[0077] The control unit 3 uses a lifting mechanism 60, as shown by arrow 401 in Figure 8, to continue lowering the grinding mechanism 70. Thus, as shown in Figures 8 and 9, until the lower surface of the grinding stone 77 contacts and presses against the upper surface 6 of the wafer 5, the probe 110 rises relative to the housing 101 as the grinding mechanism 70 descends. The height of the probe 110, detected by the detection unit 151, changes in the +Z direction (refer to arrow 400 in Figure 8). That is, the measurement value of the upper surface height measuring device 80, until the lower surface of the grinding stone 77 contacts the upper surface 6 of the wafer 5, changes in the +Z direction by the same amount as the change in the height of the grinding mechanism 70 per unit time in the -Z direction, as identified by the Z-axis encoder 65. Therefore, the change in the measurement value of the upper surface height measuring device 80 becomes a change compared to the change in the height of the grinding mechanism 70.

[0078] On the other hand, after the lower surface of the grinding stone 77 contacts the upper surface 6 of the wafer 5, as the grinding mechanism 70 descends, the void 210 is flattened by the grinding stone 77, and the upper surface 6 of the wafer 5 begins to descend in the -Z direction. Therefore, the tip of the probe 110, which is in contact with the upper surface 6, also begins to descend in the -Z direction. Therefore, the probe 110, which has risen relative to the housing 101 as the grinding mechanism 70 descends, will descend. Therefore, the change in the measurement value of the upper surface height measuring device 80 in the +Z direction per unit time is no longer the same as the change in the height of the grinding mechanism 70 in the -Z direction per unit time. That is, the change in the measurement value of the upper surface height measuring device 80 is no longer a change compared to the change in the height of the grinding mechanism 70.

[0079] Then, the control unit 3 detects that the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5 held by the holding surface 22 by recognizing that the change in the measurement value of the upper surface height measuring device 80 is no longer a change compared with the change in the height of the grinding mechanism 70. Then, at this time, the control unit 3 stops the descent of the grinding mechanism 70 performed by the lifting mechanism 60, and obtains the height value of the grinding mechanism 70 recognized by the Z-axis encoder 65 as the first height Z1 (refer to FIG. 8), and stores it in the memory of the control unit 3 and / or the memory unit 4. In addition, in FIG. 2, a hypothetical scale 200 is shown, which represents the height of the grinding mechanism 70 recognized by the Z-axis encoder 65. Thereafter, the control unit 3 raises the grinding mechanism 70 using the lifting mechanism 60.

[0080] Next, the control unit 3 calculates the height of the grinding mechanism 70, i.e. the origin height, when the lower surface of the grinding stone 77 is in contact with the holding surface 22 of the chuck table 20, based on the first height Z1 of the lifting mechanism 60.

[0081] That is, the control unit 3 calculates the origin height Z0 of the grinding mechanism 70 as shown in the following formula (1), by subtracting the thickness V1 of the aforementioned cavity 210, the thickness W1 of the pre-prepared wafer 5, and the thickness T1 of the adhesive film 8 from the first height Z1 of the grinding mechanism 70 (refer to Figures 8 and 9). Z0 = Z1 - V1 - W1 - T1 … (1)

[0082] That is, in this step, as shown in Figures 8 and 9, when the lower surface of the grinding stone 77 contacts the upper surface 6 of the wafer 5 and the void 210 begins to be flattened by the grinding stone 77, the descent of the grinding mechanism 70 is stopped and a first height Z1 is obtained. Therefore, the thickness of the void 210 remains substantially unchanged. Therefore, when the lower surface of the grinding stone 77 contacts the upper surface 6 of the wafer 5 and the first height Z1 of the grinding mechanism 70 is obtained, the wafer 5, the adhesive film 8, and the void 210 exist between the lower surface of the grinding stone 77 and the holding surface 22.

[0083] Therefore, the control unit 3 can subtract the thickness of the wafer 5, the film 8, and the void 210 from the first height Z1 by the calculation shown in the above formula (1), thereby obtaining the height of the grinding mechanism 70, i.e., the origin height Z0, when the lower surface of the grinding stone 77 is in contact with the holding surface 22 of the chuck stage 20. The control unit 3 stores the obtained origin height Z0 of the grinding mechanism 70 in the memory of the control unit 3 and / or the memory unit 4.

[0084] As described above, in this embodiment, during the memory step, the lifting mechanism 60 is lowered from above the wafer 5 held by the holding surface 22, and the height of the grinding mechanism 70 when the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5 is memorized. Then, the origin height of the grinding mechanism 70 is determined based on this height.

[0085] Thus, in this embodiment, for example, the origin height of the grinding mechanism 70 can be determined without using a mounting block after replacing the grinding stone 77. Therefore, installation can be performed quickly. Furthermore, by using the wafer 5 for installation, the grinding of the wafer 5 can continue immediately after installation. Therefore, the work efficiency from installation to the grinding step can be improved. Since no mounting sensor is used, installation can be performed with a low-cost configuration.

[0086] Furthermore, in this embodiment, during the holding step, a cavity 210, serving as an elastic portion, is formed between the central portion 51 of the lower surface of the wafer 5 and the holding surface 22. Therefore, when the lower surface of the grinding stone 77 has come into contact with the upper surface 6 of the wafer 5, the cavity 210 deforms to mitigate the impact of contact, thereby preventing damage to the lower surface of the grinding stone 77.

[0087] Furthermore, when the grinding mechanism 70 stops descending and reaches the first height Z1, as shown in FIG10, there is also a situation where the cavity 210 is significantly flattened by the grinding stone 77, and the thickness V1 of the cavity 210 changes significantly. In this case, the control unit 3 corrects the thickness V1 according to the change in the thickness of the cavity 210 and then performs the operation shown in the above formula (1).

[0088] Furthermore, as shown in Figure 11, when the grinding mechanism 70 stops descending and reaches the first height Z1, there is also a situation where the cavity 210 is completely flattened by the grinding stone 77 and the adhesive film 8 contacts the holding surface 22. In this case, instead of the above formula (1), the following formula (2) is used to calculate the origin height Z0 of the grinding mechanism 70, which is the height of the grinding mechanism 70 when the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5, i.e., the first height Z1, by subtracting the previously known thickness W1 of the wafer 5 and the thickness T1 of the adhesive film 8. Z0 = Z1 - W1 - T1… (2)

[0089] Also, after obtaining the first height Z1 in a manner where the thickness of the cavity 210 does not change, the descent of the grinding mechanism 70 can be restarted. When the cavity 210 is completely flattened by the grinding stone 77, the grinding mechanism 70 is stopped, and the second height Z2 of the grinding mechanism 70 shown in FIG11 is obtained. The thickness V1 of the cavity 210 is obtained by subtracting the second height Z2 from the first height Z1 as shown in the following formula (3). V1=|(Z1-Z2)|…(3) In addition, when the change in height of the grinding mechanism 70 per unit time in the -Z direction is compared with the change in height of the upper surface height measuring device 80 per unit time in the +Z direction, it is detected that the cavity 210 has been completely flattened.

[0090] Furthermore, in this embodiment, the control unit 3, which is a contact detection unit, detects that the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5 by utilizing the condition that the measurement value of the upper surface height measuring device 80 no longer changes, and calculates the first height Z1 of the grinding mechanism 70 at that time.

[0091] Regarding this point, the control unit 3 can also use the rotation detection unit 78 shown in FIG1 to detect that the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5. As described above, the rotation detection unit 78 detects the rotational speed of the grinding stone 77. In this embodiment, the rotation detection unit 78 detects the rotational speed of the spindle 72 on which the grinding stone 77 is mounted as the rotational speed of the grinding stone 77.

[0092] In this configuration, during the memory step, when the grinding mechanism 70 is lowered from above the wafer 5 held by the holding surface 22, the control unit 3 controls the spindle motor 73 to rotate the spindle 72 and the grinding stone 77 mounted on the front end of the spindle 72, and uses the rotation detection unit 78 to detect the rotation speed of the spindle 72.

[0093] In this case, before the lower surface of the grinding stone 77 contacts the upper surface 6 of the wafer 5, the control unit 3 stops the output of the spindle motor 73, causing the spindle 72 to rotate by inertia.

[0094] Subsequently, as the grinding mechanism 70 descends, if the lower surface of the grinding stone 77 contacts and presses against the upper surface 6 of the wafer 5, the rotational speed of the spindle 72 detected by the rotation detection unit 78 will slow down due to the frictional resistance between the grinding stone 77 and the upper surface 6 of the wafer 5. Then, the control unit 3 can detect that the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5 by detecting the slowdown of the rotational speed of the spindle 72 detected by the rotation detection unit 78. At this time, the descent of the grinding mechanism 70 performed by the lifting mechanism 60 is stopped, and the height value of the grinding mechanism 70 identified by the Z-axis encoder 65 is obtained as the first height Z1. Furthermore, even with this configuration, when the lower surface of the rotating grinding stone 77 comes into contact with the upper surface 6 of the wafer 5, the cavity 210 will deform to mitigate the impact of contact, thus preventing damage to the lower surface of the grinding stone 77.

[0095] Furthermore, the rotation detection unit 78 may also be configured to detect the power consumed by the spindle motor 73 to rotate the spindle 72. In this case, the spindle 72 will rotate freely before the lower surface of the grinding stone 77 contacts the upper surface 6 of the wafer 5, so the power consumption of the spindle motor 73 detected by the rotation detection unit 78 becomes smaller.

[0096] On the other hand, if the lower surface of the grinding stone 77 contacts and presses against the upper surface 6 of the wafer 5, the power consumption of the spindle motor 73, as detected by the rotation detection unit 78, becomes larger due to the aforementioned frictional resistance. Then, the control unit 3 can detect that the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5 based on the increased power consumption detected by the rotation detection unit 78. Furthermore, the rotation detection unit 78 can also be configured to detect the load current value of the spindle motor 73 as the power consumption of the spindle motor 73.

[0097] Furthermore, the rotation detection unit 78 may also include: a circular plate disposed at the upper end of the main shaft 72 and having a gap formed therein; and a sensor that detects the gap of the circular plate (neither shown in the figure). In this case, the rotation detection unit 78 can determine the rotation speed of the main shaft 72 by detecting the gap of the circular plate that rotates together with the main shaft 72 using the sensor.

[0098] Furthermore, in this embodiment, a cavity 210 is formed as an elastic portion disposed between the holding surface 22 and the central portion 51 of the lower surface of the wafer 5. Regarding this point, as the elastic portion, a sponge or air bladder may be disposed between the adhesive film 8 and the holding surface 22 to replace the cavity 210. In this case, during the holding step, the cavity 210 is not formed between the holding surface 22 and the central portion 51 of the lower surface of the wafer 5, and the frame unit 9 containing the wafer 5 is held by the chuck stage 20. Furthermore, in this case, during the memory step, after obtaining the first height Z1, the control unit 3 uses the thickness of the elastic portion such as the sponge or air bladder to replace the thickness V1 of the cavity 210 in the above formula (1) to calculate the origin height Z0 of the grinding mechanism 70.

[0099] Alternatively, a thicker and more elastic adhesive film can be used as the adhesive film 8 of the frame unit 9, and the adhesive film 8 can be used as the elastic part. Even in this case, during the holding step, a void 210 will not be formed between the holding surface 22 and the central portion 51 of the lower surface of the wafer 5, and the frame unit 9 containing the wafer 5 is held by the chuck stage 20. In this case, during the memory step, after obtaining the first height Z1, the control unit 3 replaces the above formula (1) and uses the above formula (2) to calculate the origin height Z0 of the grinding mechanism 70, which is the height of the grinding mechanism 70 when the lower surface of the grinding stone 77 has contacted the upper surface 6 of the wafer 5, i.e., the first height Z1, by subtracting the pre-knowledged thickness W1 of the wafer 5 and the thickness T1 of the adhesive film 8.

[0100] Furthermore, in this embodiment, the wafer 5 is processed as a frame unit 9. The frame unit 9 containing the wafer 5 is held by the chuck stage 20 by the clamp 31 of the chuck stage 20 supporting the ring frame 7 of the frame unit 9. In this respect, the wafer 5 can also be processed in a state where it is not a frame unit 9. In this case, for example, as shown in FIG12, the holding surface 22 of the chuck stage 20 may also have a central holding surface 221 and an annular holding surface 222.

[0101] In this configuration, during the holding step, the control unit 3 controls the suction valve 270 (refer to FIG2) to connect the suction source 240 with the annular holding surface 222, thereby attracting and holding, for example, the outer periphery of the wafer 5 having the protective film 15 through the annular holding surface 222.

[0102] The control unit 3 further controls the air valve 271 (refer to FIG2) to connect the air supply source 241 with the central holding surface 221, thereby ejecting air from the central holding surface 221. In this way, a cavity 210 as an elastic part can be formed between the holding surface 22 and the central portion 51 of the lower surface of the wafer 5.

[0103] In this case, the control unit 3 uses, for example, the following formula (4) instead of the above formula (1), to calculate the origin height Z0 of the grinding mechanism 70 by subtracting the thickness V1 of the cavity 210, the thickness W1 of the pre-held wafer 5, and the thickness H1 of the protective film 15 from the first height Z1 of the grinding mechanism 70. Z0 = Z1 - V1 - W1 - H1... (4)

[0104] Furthermore, in this embodiment, a wafer 5 is used as a plate-like object held on the holding surface 22 for mounting purposes. In this regard, other plate-like objects such as trimming plates may also be held on the holding surface 22 instead of the wafer 5.

[0105] Furthermore, as a height identification unit for identifying the height of the grinding mechanism 70, a linear scale 25 shown in FIG1 can be used instead of the Z-axis encoder 65. The linear scale 25 includes: a reading unit 26, which is provided on the Z-axis moving stage 63 of the lifting mechanism 60 and moves together with the grinding mechanism 70 in the Z-axis direction; and a scale part 27, which is provided on the surface of the Z-axis guide rail 61. By reading the scale of the scale part 27 by the reading unit 26, the height of the grinding mechanism 70, which moves in the Z-axis direction by the lifting mechanism 60, can be identified. [Simplified Explanation of the Diagram]

[0010] Figure 1 is a perspective view showing the structure of the grinding apparatus. Figure 2 is a partial cross-sectional side view showing the structure of the grinding apparatus. Figure 3 is a perspective view showing the structure of the upper surface height measuring device. Figure 4 is a cross-sectional view showing the structure of the upper surface height measuring device. Figure 5 is a schematic diagram showing the holding step. Figure 6 is a schematic diagram showing the holding step. Figure 7 is a cross-sectional view showing the holding step. Figure 8 is a schematic diagram showing the memory step. Figure 9 is a cross-sectional view showing the memory step. Figure 10 is a schematic diagram showing another memory step. Figure 11 is a schematic diagram showing another memory step. Figure 12 is a cross-sectional view showing another structure of the holding surface.

Claims

1. An installation method using a grinding apparatus comprising: a chuck table holding a plate-like object on its holding surface; a grinding mechanism grinding the plate-like object held on the holding surface with a grinding stone; a lifting mechanism moving the grinding mechanism in a direction perpendicular to the holding surface; and a height recognition unit recognizing the height of the grinding mechanism after it has been moved by the lifting mechanism, wherein the installation method moves the grinding mechanism using the lifting mechanism and memorizes the height of the grinding mechanism when the lower surface of the grinding stone is in contact with the holding surface, wherein... The grinding mechanism includes: an upper surface height measuring device, which moves along with the grinding mechanism in a direction perpendicular to the holding surface via a lifting mechanism to measure the upper surface height of the plate held by the holding surface; and a contact detection unit, which begins measuring the upper surface height of the plate by the upper surface height measuring device before the grinding mechanism is lowered and the lower surface of the grinding stone contacts the plate, and detects that the lower surface of the grinding stone has contacted the upper surface of the plate by continuing to lower the grinding mechanism and pressing the lower surface of the grinding stone against the upper surface of the plate, and detects that the change in the measurement value of the upper surface height measuring device is no longer a change relative to the change in the height of the grinding mechanism. The installation method includes: The holding step involves the chuck table holding the plate by placing an elastic portion or cavity between the central portion of the lower surface of the plate and the holding surface; and the memory step involves the grinding mechanism, on which the grinding stone is mounted, descending from above the plate held by the holding surface, and memorizing the height of the grinding mechanism when the lower surface of the grinding stone has come into contact with the upper surface of the plate held by the holding surface, as detected by the contact detection unit.

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