Grinding device

Abstract

The present invention provides a grinding device that recognizes a replacement timing of a chuck table. A grinding device (1) is used, which has a holding unit (2) that holds a wafer (14), a grinding unit (3) that grinds the wafer, and a holding surface height measurer (51) that measures the height of a holding surface (210). The wafer is held on the holding surface in a state parallel to the lower surface (342) of a grinding stone (340) and is ground by the grinding stone. The height of the holding surface of a new chuck table (20) is measured by the holding surface height measurer (51), and the height of the holding surface is stored in a storage section (60). When the height of the holding surface stored in the storage section has decreased by a prescribed distance (72) set by a distance setting section (61), the replacement timing of the chuck table (20) is judged by a judging section (62).

Description

Technical Field

[0001] This invention relates to grinding apparatus. Background Technology

[0002] As disclosed in Patent Document 1, a grinding apparatus for grinding a workpiece held on a chuck table to a predetermined thickness using a grinding wheel includes: a holding surface height measuring device that measures the height of the upper surface of a frame supporting a porous component as the holding surface height in order to identify the thickness of the workpiece; an upper surface height measuring device that measures the upper surface height of the workpiece held on the holding surface; and a calculation unit that calculates the difference between the height measured by the holding surface height measuring device and the height measured by the upper surface height measuring device.

[0003] Furthermore, as disclosed in Patent Document 2, in the grinding apparatus, self-grinding is performed by grinding the retaining surface with the grinding tool in order to make the lower surface of the grinding tool parallel to the retaining surface that holds the wafer. Besides forming a retaining surface parallel to the lower surface of the grinding tool, self-grinding is also performed, for example, to remove grinding chips trapped in the porous component and restore the reduced attractive force of the retaining surface caused by grinding chips entering and remaining in the porous component from the retaining surface.

[0004] Patent Document 1: Japanese Patent Application Publication No. 2014-237210

[0005] Patent Document 2: Japanese Patent Application Publication No. 2018-094671

[0006] In grinding equipment, the height of the holding face decreases whenever self-grinding is performed. When the height of the holding face is too low, even if the grinding wheel descends to its maximum height that allows the grinding feed unit to lower the grinding wheel, it cannot make contact with the holding face. In this state, self-grinding cannot be performed, and therefore the chuck table needs to be replaced. Therefore, there is a challenge in grinding equipment to identify when the chuck table needs replacing. Summary of the Invention

[0007] The present invention is a grinding apparatus comprising at least: a holding unit on which a chuck table is mounted, the chuck table holding a wafer on a holding surface; a grinding unit grinding the wafer using a grinding wheel; and a holding surface height measuring device for measuring the height of the holding surface. The grinding apparatus holds the wafer on the holding surface, which is being ground by the grinding wheel and is parallel to the lower surface of the grinding wheel. The grinding apparatus further comprises: a storage unit for storing the height of the holding surface of the chuck table of a new wafer, as measured by the holding surface height measuring device; a distance setting unit for setting a predetermined distance; and a judgment unit for determining that it is time to replace the chuck table when the height of the holding surface drops from the height stored in the storage unit to the predetermined distance set by the distance setting unit.

[0008] The present invention is a grinding apparatus comprising at least: a holding unit on which a chuck table is mounted, the chuck table holding a wafer on a holding surface; a grinding unit grinding the wafer using a grinding wheel; and a holding surface height measuring device for measuring the height of the holding surface. The grinding apparatus holds the wafer on the holding surface, which is being ground by the grinding wheel and is parallel to the lower surface of the grinding wheel. The holding unit has a table base with a support surface supporting the lower surface of the chuck table. The grinding apparatus comprises: a setting unit that sets a height above a predetermined distance from the support surface as the maximum operating height of the chuck table; and a determining unit that determines the replacement period of the chuck table when the height of the holding surface drops to the maximum operating height set by the setting unit.

[0009] The grinding apparatus according to the present invention can automatically determine the replacement period of the chuck table, thus achieving high efficiency in the chuck table replacement operation. Attached Figure Description

[0010] Figure 1 It is a three-dimensional view showing the entire grinding device.

[0011] Figure 2 This is a cross-sectional view of the chuck worktable of the new product.

[0012] Figure 3 This is a cross-sectional view showing a self-grinding chuck table.

[0013] Figure 4 This is a cross-sectional view showing the chuck table during a replacement period.

[0014] Figure 5 This is a cross-sectional view showing the measurement of the height of the upper surface of a gauge block placed on a base.

[0015] Figure 6This is a cross-sectional view showing a self-grinding chuck table.

[0016] Figure 7 This is a cross-sectional view showing the chuck table during a replacement period.

[0017] Label Explanation

[0018] 1: Grinding device; 10: Base; 2: Holding unit; 20: Chuck table; 21: Suction part; 210: Holding surface; 22: Frame; 220: Upper surface of frame; 221: Recess; 222: Through hole; 224: Lower surface; 23: Base; 230: Support surface; 231: Threaded hole; 24: Screw; 25: Rotation axis; 27: Cover; 28: Fold; 3: Grinding unit; 30: Spindle; 31: Housing; 32: Spindle motor; 33: Mounting seat; 34: Grinding wheel; 340: Grinding tool; 341: Grinding wheel base; 342: Lower surface; 35: Rotation axis; 4: Grinding feed unit; 40: Ball screw; 41: Guide rail; 42: Z-axis motor; 43: Lifting plate ; 44: Holder; 45: Rotation axis; 5: Thickness measuring unit; 50: Upper surface height measuring device; 51: Holding surface height measuring device; 510: Measuring head; 5100: Contact part; 5101: Reading part; 511: Storage part; 60: Storage part; 61: Distance setting part; 62: Judgment part; 70: Origin height (height stored in the storage part); 72: Specified distance; 71: Limit height (height that has decreased by a specified distance from the height stored in the storage part); 80: Setting part; 81: Second judgment part; 82: Gauge block; 820: Upper surface; 821: Specified distance; 822: Usage limit height; 90: Second origin height; 91: Second limit height; 92: Mid-course height. Detailed Implementation

[0019] (Structure of the grinding device)

[0020] Figure 1 The grinding apparatus 1 shown is a processing apparatus that uses the grinding unit 3 to perform grinding processing on the wafer 14 held by the chuck table 20. The structure of the grinding apparatus 1 will be described below.

[0021] like Figure 1 As shown, the grinding apparatus 1 includes: a base 10 extending in the Y-axis direction; and a column 11 erected on the +Y direction side of the base 10.

[0022] A grinding feed unit 4, which supports the grinding unit 3 and allows it to be raised and lowered, is provided on the side of the column 11 in the -Y direction. The grinding unit 3 includes, for example: a spindle 30 having a rotation axis 35 in the Z direction; a housing 31 that supports the spindle 30 and allows it to rotate; a spindle motor 32 that drives the spindle 30 to rotate about the rotation axis 35; a mounting base 33 connected to the lower end of the spindle 30; and a grinding wheel 34 that is detachably mounted on the lower surface of the mounting base 33.

[0023] The grinding wheel 34 has a grinding wheel base 341 and a plurality of generally cuboid grinding tools 340 arranged in a ring on the lower surface of the grinding wheel base 341. The lower surface 342 of the grinding tools 340 is the grinding surface that contacts the wafer 14.

[0024] The spindle 30 is rotated by the spindle motor 32, thereby rotating the mounting base 33 connected to the spindle 30 and the grinding wheel 34 mounted on the lower surface of the mounting base 33 together.

[0025] The grinding feed unit 4 includes: a ball screw 40 having a rotation axis 45 in the Z-axis direction; a pair of guide rails 41 arranged parallel to the ball screw 40; a Z-axis motor 42 that causes the ball screw 40 to rotate about the rotation axis 45; a lifting plate 43 with a nut inside that is screwed into the ball screw 40, and the side of the lifting plate 43 slidingly contacting the guide rails 41; and a retainer 44 connected to the lifting plate 43 to support the grinding unit 3.

[0026] When the ball screw 40 is driven by the Z-axis motor 42 to rotate around the rotation axis 45, the lifting plate 43 is guided by the guide rail 41 to move up and down in the Z-axis direction, and the grinding wheel 34 of the grinding unit 3 held in the holder 44 moves in the Z-axis direction.

[0027] A holding unit 2 for holding the wafer 14 is provided on the base 10.

[0028] like Figure 2 As shown, the holding unit 2 has a worktable base 23 and a chuck worktable 20 that is detachably mounted on the worktable base 23. The upper surface of the worktable base 23 is a support surface 230 that supports the lower surface 224 of the chuck worktable 20.

[0029] The chuck stage 20 includes: a suction section 21 having a porous component; and a frame 22 supporting the suction section 21. The upper surface of the suction section 21 is a holding surface 210 for holding the wafer 14. In the new chuck stage 20, the upper surface 220 of the frame 22 is formed coplanarly with the holding surface 210.

[0030] The attraction section 21 is connected to an attraction source (not shown). By activating the attraction source, the resulting attraction force is transmitted to the holding surface 210. For example, by activating the attraction source while the wafer 14 is placed on the holding surface 210, the wafer 14 can be attracted and held on the holding surface 210.

[0031] A recess 221 recessed in the -Z direction is formed on the outermost radial periphery of the frame 22, and a plurality of through holes 222 formed in the recess 221 along the Z-axis direction are provided therein. In addition, the support surface 230 of the worktable base 23 has, for example, the same number of threaded holes 231 as the number of through holes 222.

[0032] With the chuck table 20 supported on the support surface 230 of the table base 23, the screw 24 corresponding to the threaded hole 231 passes through the through hole 222 from the +Z direction side and engages with the threaded hole 231, thus forming the structure of the chuck table 20 mounted on the table base 23.

[0033] Additionally, the holding unit 2 has a rotating unit (not shown). By activating this rotating unit, the worktable base 23 and the chuck worktable 20 mounted on the worktable base 23 can rotate about a rotation axis 25 parallel to the Z-axis.

[0034] like Figure 1 As shown, a cover 27 and pleats 28 that are telescopically connected to the cover 27 are arranged around the chuck worktable 20. For example, when the holding unit 2 moves in the Y-axis direction, the cover 27 moves together with the holding unit 2 in the Y-axis direction, and the pleats 28 extend and retract.

[0035] The grinding apparatus 1 includes a thickness measuring unit 5 for measuring the thickness of the wafer 14. The thickness measuring unit 5 includes an upper surface height measuring device 50 for measuring the height of the upper surface 140 of the wafer 14 in a non-contact manner. The upper surface height measuring device 50 is, for example, a laser-type height measuring device, which projects a laser beam toward the upper surface 140 of the wafer 14 held on the holding surface 210 of the chuck stage 20 and measures the reflected light, thereby measuring the height of the upper surface 140 of the wafer 14.

[0036] Alternatively, the upper surface height measuring device 50 may also have a measuring head that contacts the upper surface of the wafer 14 and a reading section for reading the height of the measuring head.

[0037] Additionally, the thickness measuring unit 5 includes a holding surface height measuring device 51 for measuring the height of the holding surface 210. For example... Figure 2As shown, the holding surface height measuring device 51 is a contact-type height measuring device, having a measuring head 510 that contacts the upper surface 220 of the frame 22 of the chuck table 20 and a housing member 511 for housing the measuring head 510. The measuring head 510 is housed in the housing member 511 with a portion protruding from the housing member 511 in the -Z direction.

[0038] The end of the measuring head 510 in the -Z direction is a contact part 5100 that contacts the measuring part, and the end of the measuring head 510 in the +Z direction is a reading part 5101 for reading the scale, which is provided in the storage component 511.

[0039] In addition, the reading unit can also read the height of the measuring head 510.

[0040] The height of the holding surface 210 of the chuck table 20 is measured by making the contact portion 5100 of the measuring head 510 of the holding surface height measuring device 51 contact the upper surface 220 of the frame 22 and reading the height position of the reading portion 5101.

[0041] In addition, the surface height measuring device 51 can also measure the height of the upper surface of the frame in a non-contact manner.

[0042] In addition, in the case of Figure 3 When measuring the height of the holding surface 210 of the chuck worktable 20, whose surface is ground and shaped into a cone, the contact portion 5100 of the measuring head 510 of the holding surface height measuring device 51 is brought into contact with the upper surface 220 of the frame 22 to read the scale of the reading portion 5101, and the height of the upper surface 220 of the frame 22 is measured. An appropriate correction value is added to the measured height of the upper surface 220 of the frame 22, thereby enabling the measurement of the height of the holding surface 210.

[0043] Figure 1 The thickness measurement unit 5 shown has a thickness calculation unit (not shown), which includes a CPU, memory, etc. The thickness of the wafer 14 can be calculated by calculating the difference between the height of the upper surface 140 of the wafer 14 measured by the upper surface height measuring device 50 and the height of the holding surface 210 measured by the holding surface height measuring device 51 in the thickness calculation unit.

[0044] Grinding device 1 has storage Figure 2 The storage unit 60 shows the height of the holding surface 210 of the chuck table 20 of the new product. The storage unit 60 has a storage device such as a memory or HDD, and is capable of storing the height of the holding surface 210 of the chuck table 20 of the new product as measured by the holding surface height measuring device 51.

[0045] The grinding apparatus 1 includes: a distance setting unit 61, which sets a predetermined distance; and a judgment unit 62, which determines that the chuck table 20 is in the replacement period when the holding surface 210 drops from the height of the holding surface 210 stored in the storage unit 60 to the height of the predetermined distance set by the distance setting unit 61.

[0046] (Grinding of wafers)

[0047] In use Figure 1 When the grinding apparatus 1 shown performs grinding on the wafer 14, the wafer 14 is first placed on the holding surface 210 of the chuck stage 20. Then, an attraction source (not shown) connected to the chuck stage 20 is activated to transfer the generated attraction force to the holding surface 210. As a result, the wafer 14 is attracted and held on the holding surface 210.

[0048] With the wafer 14 held on the holding surface 210 by being attracted, the chuck stage 20 is moved in the +Y direction using a Y-axis moving unit (not shown) or the like to position the wafer 14 below the grinding unit 3.

[0049] Furthermore, a rotary unit (not shown) is used to rotate the chuck stage 20 about the rotation axis 25, thereby rotating the wafer 14 held on the holding surface 210, and a spindle motor 32 is used to rotate the grinding wheel 340 about the rotation axis 35.

[0050] With the wafer 14 rotating about the rotation axis 25 and the grinding wheel 340 rotating about the rotation axis 35, the grinding unit 3 is lowered in the -Z direction using the grinding feed unit 4. By lowering the grinding wheel 340 in the -Z direction, the lower surface 342 of the grinding wheel 340 comes into contact with the upper surface 140 of the wafer 14.

[0051] With the lower surface 342 in contact with the upper surface 140 of the wafer 14, the grinding tool 340 is further lowered in the -Z direction to grind the wafer 14.

[0052] During the grinding process of wafer 14, the thickness of wafer 14 is measured using thickness measuring unit 5. Specifically, the height of the upper surface 140 of wafer 14 is measured using upper surface height measuring device 50, and the height of the holding surface 210 is measured using holding surface height measuring device 51. The thickness of wafer 14 is measured by subtracting the height of the holding surface 210 from the height of the upper surface 140 of wafer 14 using a thickness calculation unit (not shown).

[0053] After grinding the wafer 14 to the specified thickness, the grinding process is completed. The grinding unit 3 is moved in the +Z direction by the grinding feed unit 4 so that the grinding tool 340 leaves the upper surface 140 of the wafer 14. Then the wafer 14 is removed from the holding surface 210 of the chuck stage 2.

[0054] (Self-grinding)

[0055] The grinding of wafer 14 is performed with the holding surface 210 parallel to the lower surface 342 of the grinding wheel 340, such as... Figure 2 As shown, the upper surface of the new chuck table 20 is formed flat. Therefore, for example, after replacing the chuck table with a new one, the chuck table 20 is self-ground, and the retaining surface 210 is shaped so that the retaining surface 210 is parallel to the lower surface 342 of the grinding wheel 340.

[0056] Furthermore, when grinding chips generated during the grinding process of the wafer 14 enter the interior of the suction section 21 from the holding surface 210 and remain inside the suction section 21, the suction force transmitted to the holding surface 210 may decrease. Therefore, in order to remove the grinding chips remaining inside the suction section 21, self-grinding of the chuck stage 20 is performed. In the grinding apparatus 1, for example, after grinding a predetermined number of wafers 14 consecutively, self-grinding of the chuck stage 20 is performed, thereby removing the grinding chips inside the suction section 21.

[0057] During self-grinding of the chuck table 20, such as Figure 3 As shown, the chuck table 20 rotates about the rotation axis 25, and the grinding wheel 340 rotates about the rotation axis 35. While the chuck table 20 and the grinding wheel 340 are rotating about the rotation axis 25, the grinding wheel 340 is lowered in the -Z direction using the grinding feed unit 4. As a result, the lower surface 342 of the grinding wheel 340 contacts the holding surface 210, and grinding is performed on the holding surface 210 and the upper surface 220 of the frame 22.

[0058] Furthermore, the surface 210 and the upper surface 220 of the frame 22 are formed coplanarly (in such a way as to become the same plane).

[0059] (Determining when to replace the chuck table)

[0060] Whenever the chuck table 20 performs self-grinding, the height of the holding surface 210 decreases. Soon, the height of the holding surface 210 reaches the limit height at which the lower surface 342 of the grinding wheel 340 cannot contact the holding surface 210 even when the grinding feed unit 4 is used to lower the grinding wheel 340.

[0061] Therefore, the height of the retaining surface 210 is measured using the retaining surface height measuring device 51 during the self-grinding of the chuck table 20. When the height of the retaining surface 210 of the chuck table 20 reaches the limit height, the chuck table 20 is replaced.

[0062] In the grinding apparatus 1, when it is time to replace the chuck table 20, the determination unit 62 determines this situation. The operation of the grinding apparatus 1 when it is determined that it is time to replace the chuck table 20 will be explained below.

[0063] First, such as Figure 2 As shown, the contact portion 5100 of the holding surface height measuring device 51 is brought into contact with the upper surface 220 of the frame 22 of the new chuck table 20 beforehand. At this time, as shown, the reading portion 5101 is positioned at the origin height 70 corresponding to the height of the holding surface 210 of the new chuck table 20, and the origin height 70 is stored in the storage portion 60 as the height corresponding to the height of the holding surface 210 of the new chuck table 20. Furthermore, a predetermined distance 72 is set in the distance setting portion 61. Here, the height that descends the predetermined distance 72 from the origin height 70 is the limit height 71 corresponding to the height of the holding surface 210 when the holding surface 210 of the chuck table 20 is positioned at the height at which it should be replaced.

[0064] like Figure 3 As shown, when the chuck table 20 is self-grinding, the height of the holding surface 210 decreases. For example, after multiple self-grinding cycles, such as... Figure 4 As shown, the chuck table 20 is in a state of corresponding wear.

[0065] In this state, the contact portion 5100 of the holding surface height measuring device 51 is brought into contact with the holding surface 210, and the height of the reading portion 5101 is read. Figure 4 In this configuration, the reading unit 5101 is located at a height 71 that is a predetermined distance 72 lowered from the origin height 70 of the storage unit 60. When the height of the reading unit 5101 reaches the limit height 71, the holding surface 210 of the chuck table 20 is considered to be positioned at a height at which it should be replaced, and the judgment unit 62 determines that it is time to replace the chuck table 20.

[0066] In the grinding device 1, the replacement period of the chuck table 20 can be automatically determined, thus achieving high efficiency in the replacement operation of the chuck table 20.

[0067] Furthermore, a structure can be provided that notifies the operator that the height of the holding surface 210 is close to the limit height 71 before the holding surface 210 is positioned at the limit height 71, for example, by connecting a notification unit (not shown) to the judgment unit 62. This enables the smooth operation of inventory confirmation and purchase arrangement of the chuck worktable 20, which is a preparation operation for changing the chuck worktable 20.

[0068] like Figure 5 As shown, the grinding apparatus 1 may also be configured to have a setting unit 80 instead of a distance setting unit 61, and a second judgment unit 81 instead of a judgment unit 62.

[0069] The setting unit 80 has the function of setting the height above a predetermined distance from the support surface 230 as the operating limit height of the chuck table 20. In addition, the second determination unit 81 has the function of determining that if the height of the holding surface 210 measured by the holding surface height measuring device 51 drops to the operating limit height set by the setting unit 80, it is determined that it is time to replace the chuck table.

[0070] In this structure, the replacement period of the chuck table 20 is determined as follows.

[0071] First, such as Figure 5 As shown, with the chuck worktable 20 not mounted on the support surface 230 of the worktable base 23, a gauge block 82 with a height of a specified distance 821 is placed on the support surface 230 of the worktable base 23.

[0072] Then, with the gauge block 82 placed on the support surface 230 of the worktable base 23, the contact portion 5100 of the holding surface height measuring device 51 is brought into contact with the upper surface 820 of the gauge block 82. At this time, the reading portion 5101 is positioned at a height above a predetermined distance 821 from the support surface 230, which corresponds to the second limit height 91 of the chuck worktable 20's operating limit height 822. The second limit height 91 is set in the setting portion 80.

[0073] exist Figure 6 The image shows a chuck table 20 in a self-grinding process. Figure 6 In this case, the reading section 5101 of the surface height measuring device 51 is located at a height 92, which is higher than the second limit height 91. Therefore, it is not during the replacement period of the chuck table 2.

[0074] exist Figure 7 The image shows a chuck table 2 that further reduces the height of the retaining surface 210 through self-grinding. Figure 7In this case, the reading section 5101 of the holding surface height measuring device 51 is positioned at the second limit height 91. As a result, the second judgment section 81 determines that the height of the holding surface 210 has dropped to the use limit height 822, and it is time to replace the chuck table 20.

[0075] Alternatively, the upper surface height measuring device 50 can be used instead of the holding surface height measuring device 51 to directly measure the height of the holding surface 210 of the unheld wafer, thereby determining the replacement period of the chuck stage 20.

[0076] Because the replacement period of the chuck table 20 is automatically determined in this structure, the replacement operation of the chuck table 20 can be made more efficient.

Claims

1. A grinding apparatus, comprising at least: A holding unit is equipped with a chuck stage, which holds the wafer on the holding surface; A grinding unit that uses grinding tools to grind wafers; and A surface height measuring device is used to measure the height of the retaining surface. The grinding apparatus holds the wafer on the holding surface, which is parallel to the lower surface of the grinding wheel and is being ground by the grinding wheel. in, The holding unit has a table base with a support surface that supports the lower surface of the chuck table. This grinding device has the following features: The setting unit sets the height above the specified distance from the support surface as the maximum usable height of the chuck table; and The judgment unit determines that the chuck table needs to be replaced when the height of the holding surface drops to the limit height set by the setting unit.

Images