Grinding device

Abstract

To effectively suck up grinding water containing grinding chips and its spray.SOLUTION: A cover 81, its bottom plate 91, and a holding surface 22 of a chuck table 20 form a closed space S1 surrounding a grinding wheel 77 which is grinding the back surface 102 of a wafer 100. Therefore, by connecting a spray suction source 202 to the space S1 via a suction path 95, the spray and grinding water containing grinding debris in the space S1 can be effectively sucked in with substantially no leakage. Therefore, it is possible to prevent the members outside the space S1 in the grinding device 1 from being contaminated by the spray and grinding water.SELECTED DRAWING: Figure 2

Description

Technical Field

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

Background Art

[0002] In a grinding device for grinding a wafer with an annular grinding wheel, spraying of grinding water containing grinding chips occurs. When this spraying scatters into the processing chamber, the grinding chips contained in the spraying form lumps in the processing chamber, and these lumps may fall onto the wafer and damage the wafer. For this reason, in the techniques disclosed in Patent Documents 1 and 2, a space surrounding the grinding wheel is formed by a holding surface for holding the wafer and a cover. Then, the spraying of grinding water containing grinding chips is sucked in this space to suppress damage to the wafer.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Patent Document 3

Summary of the Invention

Problems to be Solved by the Invention

[0004] However, in the grinding device, in order to form the holding surface, the holding surface is periodically ground. For this reason, due to the lowering of the holding surface, leakage may occur in the space surrounded by the holding surface and the cover, and it may become difficult to sufficiently suck the spraying.

[0005] Therefore, an object of the present invention is to satisfactorily suck grinding water containing grinding chips and spraying of grinding water containing grinding chips.

Means for Solving the Problems

[0006] The grinding apparatus of the present invention (this grinding apparatus) comprises a chuck table that holds and rotates a wafer by a holding surface, a grinding mechanism that rotates an annular grinding wheel mounted on a mount positioned at the tip of a spindle and grinds the wafer by bringing the lower surface of the grinding wheel into contact with the wafer held on the holding surface, a lifting mechanism that moves the grinding mechanism in the vertical direction, and a grinding water supply unit that supplies grinding water to the grinding wheel, and further comprises a cover mechanism that surrounds the grinding wheel during grinding of the wafer held on the chuck table, the cover mechanism having a cylindrical body that surrounds the outer surface of the grinding wheel mounted on the mount, and a through-hole through which the spindle passes, and the upper part of the cylindrical body The device comprises a cover including a top plate that closes the sides; a guide portion that supports the cover so that it can move up and down vertically; a stopper that supports the cover such that a gap is formed between the bottom surface of the top plate and the top surface of the mount when the cover is positioned in a lower position by its own weight; a positioning block that places the lower end of the cover on when the grinding mechanism is lowered by the lifting mechanism, raises the cover relative to the grinding wheel by the guide portion, and positions the cover at a predetermined height relative to the holding surface of the chuck table when grinding a wafer with the grinding wheel; and a bottom plate that closes the bottom surface of the portion of the cover that protrudes from the chuck table when it is positioned at the predetermined height.

[0007] This grinding device may be equipped with a cleaning water nozzle positioned on the bottom plate, which sprays cleaning water onto the underside of the grinding wheel. [Effects of the Invention]

[0008] In this grinding apparatus, for example, by positioning the cover at a predetermined height, a space can be formed around the grinding wheel that is grinding the wafer by the holding surfaces of the cover, bottom plate, and chuck table. As a result, the spray containing grinding debris and grinding water within this space can be effectively sucked up with virtually no leakage. Therefore, contamination of components outside the space in the grinding apparatus by these sprays and grinding water can be suppressed.

[0009] Furthermore, in this embodiment, a positioning block is provided on which the lower end of the cover rests in order to position the cover at a predetermined height. Therefore, it is easy to position the cover at a predetermined height. [Brief explanation of the drawing]

[0010] [Figure 1] This is a perspective view showing the configuration of the grinding device. [Figure 2] This is an explanatory diagram showing the configuration of the grinding device. [Figure 3] This is an explanatory diagram showing the configuration of the mounting mechanism. [Figure 4] This is an explanatory diagram showing the configuration of the grinding device. [Figure 5] This is a view along line AA in Figure 2. [Modes for carrying out the invention]

[0011] As shown in Figure 1, the grinding apparatus 1 according to this embodiment is an apparatus that grinds a workpiece, a wafer 100, with a grinding wheel 77.

[0012] Wafer 100 is, for example, a circular semiconductor wafer and includes a front surface 101 and a back surface 102. In Figure 1, the front surface 101 of wafer 100, which is facing downwards, holds multiple devices. The back surface 102 may be protected by the application of protective tape. The back surface 102 of wafer 100 becomes the workpiece surface to be ground.

[0013] The grinding device 1 comprises a rectangular parallelepiped base 10, an upwardly extending column 11, and a control unit 7 that controls each component of the grinding device 1.

[0014] An opening 13 is provided on the upper surface of the base 10. A wafer holding mechanism 30 is positioned inside the opening 13.

[0015] The wafer holding mechanism 30 includes a chuck table 20 that holds and rotates the wafer 100 by the holding surface 22, and a support mechanism 31 that rotatably supports the chuck table 20.

[0016] As shown in FIG. 2, the chuck table 20 includes a circular plate-shaped porous member 21 and a frame 23 that supports the porous member 21. The porous member 21 can be communicated with a suction source 63. By transmitting the suction force from the suction source 63 to the holding surface 22, which is the upper surface of the porous member 21, the chuck table 20 can suction and hold the wafer 100 by the holding surface 22. Note that the frame surface 24, which is the upper surface of the frame 23, is formed to be flush with the holding surface 22.

[0017] The support mechanism 31 is configured to rotatably support the chuck table 20 and rotate the chuck table 20 about a rotation axis passing through the center of the holding surface 22.

[0018] As shown in FIG. 2, the support mechanism 31 includes a chuck table base 29 that supports the chuck table 20, a rotation mechanism 32 that rotates the chuck table 20 and the chuck table base 29, a support member 28 that supports the chuck table base 29, and a plurality of support columns 27 that support the support member 28.

[0019] The rotation mechanism 32 is, for example, a pulley mechanism, and includes a motor 33 as a drive source, a driving pulley 34 attached to the shaft of the motor 33, and a driven pulley 36 that is connected to the driving pulley 34 via an endless belt 35 and is connected to the proximal end side of the chuck table base 29.

[0020] In the rotating mechanism 32, the motor 33 rotationally drives the driving pulley 34. As the driving pulley 34 rotates, the endless belt 35 rotates, causing the driven pulley 36 and the chuck table base 29 to rotate. As a result, the chuck table 20 supported by the chuck table base 29 rotates about the rotation axis passing through the center of the holding surface 22, as indicated by the arrow 601.

[0021] Further, the grinding device 1 includes a fluid circulation mechanism 60. The fluid circulation mechanism 60 is a mechanism for supplying air or water, which is a fluid, to the holding surface 22 of the chuck table 20 or applying a suction force to the holding surface 22.

[0022] The fluid circulation mechanism 60 includes a suction passage 61, a rotary joint 62 connected to the lower end of the chuck table base 29, and a suction pipe 631 communicating with the suction passage 61.

[0023] The suction passage 61 extends from the bottom surface of the porous member 21 through the frame body 23, the chuck table base 29, and the rotary joint 62.

[0024] The suction passage 61 is connected to one end side of the suction pipe 631 outside the rotary joint 62. The other end side of the suction pipe 631 is connected to a suction source 63 via a suction on-off valve 632.

[0025] The suction source 63 includes, for example, a vacuum generating device such as a vacuum pump or an ejector mechanism, and is used to communicate with the porous member 21 of the chuck table 20 and apply a suction force to the holding surface 22, which is the upper surface thereof. The suction on-off valve 632 is used to switch the communication state between the holding surface 22 and the suction source 63.

[0026] Furthermore, an air pipe 641 is connected to the suction pipe 631. One end side of the air pipe 641 communicates with the suction passage 61 via the suction pipe 631. The other end side of the air pipe 641 is connected to an air supply source 64 via an air supply on-off valve 642.

[0027] The air supply source 64, equipped with a compressor or the like, is used to supply air to the holding surface 22 of the chuck table 20. The air supply on / off valve 642 is used to switch the communication state between the holding surface 22 and the air supply source 64.

[0028] Furthermore, a water pipe 491 is connected to the air pipe 641. One end of the water pipe 491 is connected to the suction channel 61 via the air pipe 641 and the suction pipe 631. A water supply source 65 is connected to the other end of the water pipe 491 via a water supply shut-off valve 652.

[0029] The water supply source 65, equipped with a pump or the like, is used to supply water to the holding surface 22 of the chuck table 20. The water supply on / off valve 652 is used to switch the communication state between the holding surface 22 and the water supply source 65.

[0030] By supplying air and / or water to the holding surface 22 via these air pipes 641 and / or water pipes 491, it becomes easier to separate the wafer 100 held on the holding surface 22 from the holding surface 22.

[0031] As shown in Figure 1, a flat plate 39 is provided around the chuck table 20 that moves along the Y-axis direction with the chuck table 20. A bellows cover 12 that expands and contracts in the Y-axis direction is connected to the flat plate 39. Below the wafer holding mechanism 30, a Y-axis direction movement mechanism 40 is provided.

[0032] The Y-axis movement mechanism 40 moves the chuck table 20 and the grinding wheel 77 of the grinding mechanism 70 relatively in the Y-axis direction, which is parallel to the holding surface 22. In this embodiment, the Y-axis movement mechanism 40 is configured to move the wafer holding mechanism 30, including the chuck table 20, in the Y-axis direction relative to the grinding wheel 77.

[0033] The Y-axis movement mechanism 40 comprises a pair of Y-axis guide rails 42 parallel to the Y-axis direction, a Y-axis movement table 45 that slides on the Y-axis guide rails 42, a Y-axis ball screw 43 parallel to the Y-axis guide rails 42, a Y-axis motor 44 connected to the Y-axis ball screw 43, and a holder 41 that holds these components.

[0034] The Y-axis movable table 45 is slidably mounted on the Y-axis guide rail 42. A nut (not shown) is fixed to the underside of the Y-axis movable table 45. A Y-axis ball screw 43 is screwed into this nut. The Y-axis motor 44 is connected to one end of the Y-axis ball screw 43.

[0035] In the Y-axis movement mechanism 40, the Y-axis motor 44 rotates the Y-axis ball screw 43, causing the Y-axis movement table 45 to move in the Y-axis direction along the Y-axis guide rail 42. The wafer holding mechanism 30 is mounted on the Y-axis movement table 45. Therefore, as the Y-axis movement table 45 moves in the Y-axis direction, the wafer holding mechanism 30, including the chuck table 20, also moves in the Y-axis direction.

[0036] In this embodiment, the wafer holding mechanism 30, including the chuck table 20, is moved along the Y-axis direction by the Y-axis movement mechanism 40 between a holding position 301 on the -Y-direction side for holding the wafer 100 by the holding surface 22 and a processing position 302 on the +Y-direction side where the wafer 100 is ground.

[0037] 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 100 and a lifting mechanism 50 for raising and lowering the grinding mechanism 70 are provided on the front of the column 11.

[0038] The lifting mechanism 50 moves the chuck table 20 and the grinding wheel 77 of the grinding mechanism 70 relative to each other in the Z-axis direction (vertical direction) perpendicular to the holding surface 22. In this embodiment, the lifting mechanism 50 is configured to move the grinding mechanism 70, including the grinding wheel 77, in the vertical direction relative to the chuck table 20.

[0039] The lifting mechanism 50 includes a pair of Z-axis guide rails 51 parallel to the Z-axis direction, a Z-axis moving table 53 that slides on the Z-axis guide rails 51, a Z-axis ball screw 52 parallel to the Z-axis guide rails 51, a Z-axis motor 54 connected to the Z-axis ball screw 52, ​​a Z-axis encoder 55 for detecting the amount of rotation (number of rotations and rotation angle) of the Z-axis ball screw 52, ​​and a holder 56 attached to the Z-axis moving table 53. The holder 56 supports the grinding mechanism 70.

[0040] The Z-axis moving table 53 is slidably mounted on the Z-axis guide rail 51 via a sliding member 57 (see Figure 2). A nut portion 58 is fixed to the Z-axis moving table 53. A Z-axis ball screw 52 is screwed into this nut portion 58. The Z-axis motor 54 is connected to one end of the Z-axis ball screw 52.

[0041] In the lifting mechanism 50, the Z-axis motor 54 rotates the Z-axis ball screw 52, ​​causing the Z-axis moving table 53 to move in the Z-axis direction along the Z-axis guide rail 51. As a result, the holder 56 attached to the Z-axis moving table 53, and the grinding mechanism 70 supported by the holder 56, move in the Z-axis direction together with the Z-axis moving table 53.

[0042] The Z-axis encoder 55 is rotated by the Z-axis motor 54 rotating the Z-axis ball screw 52, ​​and can recognize the amount of rotation of the Z-axis ball screw 52 (number of rotations and rotation angle). In this embodiment, the control unit 7 recognizes the amount of rotation of the Z-axis ball screw 52 recognized by the Z-axis encoder 55, and based on the recognition result, can detect the height position of the grinding wheel 77 of the grinding mechanism 70 that is moved in the Z-axis direction.

[0043] The grinding mechanism 70 grinds the wafer 100 which is held by suction on the holding surface 22. The grinding mechanism 70 comprises a spindle housing 71 fixed to the holder 56, a spindle 72 rotatably held in the spindle housing 71, a spindle motor 73 that rotationally drives 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.

[0044] The spindle housing 71 is held in the holder 56 so as to extend in the Z-axis direction. The spindle 72 extends in the Z-axis direction so as to be perpendicular to the holding surface 22 of the chuck table 20 and is rotatably supported in the spindle housing 71.

[0045] The spindle motor 73 is connected to the upper end of the spindle 72. This spindle motor 73 causes the spindle 72 to rotate around an axis extending in the Z-axis direction.

[0046] The wheel mount 74 is an example of a mount positioned at the tip of the spindle 72. The wheel mount 74 is formed in a disc shape and is fixed to the lower end (tip) of the spindle 72. The wheel mount 74 supports the grinding wheel 75.

[0047] The grinding wheel 75 is formed to have an outer diameter approximately the same as the outer diameter of the wheel mount 74. The grinding wheel 75 includes an annular wheel base 76 made of a metal material. Multiple grinding wheels 77 are fixed to the lower surface of the wheel base 76, arranged in an annular pattern around its entire circumference. The grinding wheels 77 are rotated together with the spindle 72 by the spindle motor 73 and grind the back surface 102 of the wafer 100 held in the chuck table 20 with their grinding surfaces (lower surfaces).

[0048] Thus, the grinding mechanism 70 is configured to grind the wafer 100 by rotating an annular grinding wheel 77 mounted on a wheel mount 74 located at the tip of the spindle 72, and bringing the lower surface of the grinding wheel 77 into contact with the wafer 100 held on the holding surface 22 of the chuck table 20.

[0049] Furthermore, as shown in Figure 2, a grinding water channel 79 is formed inside the spindle 72, wheel mount 74, and wheel base 76. This grinding water channel 79 is connected to a grinding water source 201 via a grinding water valve 78 and is used to supply grinding water from the grinding water source 201 to the grinding wheel 77. In this embodiment, the grinding water valve 78, the grinding water channel 79, and the grinding water source 201 function as a grinding water supply unit that supplies grinding water to the grinding wheel 77.

[0050] In this embodiment, the grinding mechanism 70 may also be equipped with a retaining surface grinding wheel 175, which includes a retaining surface grinding wheel 177 as a grinding wheel, instead of the grinding wheel 75, on the wheel mount 74. The retaining surface grinding wheel 175, like the grinding wheel 75, has a wheel base 176 and a retaining surface grinding wheel 177 fixed to the lower surface of the wheel base 176.

[0051] This retaining surface grinding wheel 177 is used to perform self-grinding by grinding the upper surface of the chuck table 20, i.e., the retaining surface 22 and the frame surface 24, with the retaining surface grinding wheel 177. This self-grinding brings the retaining surface 22 and the frame surface 24 to an appropriate state. Specifically, the retaining surface 22 becomes parallel to the lower surface of the grinding wheel 77, and the frame surface 24 becomes flush with the retaining surface 22. For example, the holding surface 22 is ground by self-grinding to form a conical surface with its center as the apex, and its radial portion is ground so that it is parallel to the lower surface of the grinding wheel 77.

[0052] As shown in Figure 1, a thickness measuring device 67 is provided on the side of the opening 13 in the base 10. The thickness measuring device 67 can measure the thickness of the wafer 100 held on the holding surface 22.

[0053] The thickness measuring instrument 67 has a wafer height measuring section 68 and a holding surface height measuring section 69, which are either contact-type or non-contact-type height gauges.

[0054] The wafer height measuring unit 68 measures the height of the wafer 100 held on the holding surface 22. The holding surface height measuring unit 69 measures the height of the holding surface 22. Then, the thickness measuring instrument 67 calculates the thickness of the wafer 100 based on the difference between the measured height of the wafer 100 and the height of the holding surface 22.

[0055] Furthermore, as shown in Figures 1 and 2, the grinding apparatus 1 has a cover mechanism 80 that surrounds the grinding wheel 77 during the grinding process of the wafer 100 held on the chuck table 20.

[0056] As shown in Figure 2, the cover mechanism 80 has a cover 81 that surrounds the grinding wheel 75, which includes the grinding wheel 77. The cover 81 has a cylindrical body 82 that surrounds the grinding wheel 77, and a top plate 83 provided on the upper part of the cylindrical body 82. The cylindrical body 82 surrounds the outer surface of the grinding wheel 77 of the grinding wheel 75 mounted on the wheel mount 74. The portion of the cylindrical body 82 positioned above the chuck table 20 at its lower end is cut out so as not to come into contact with the chuck table 20. The top plate 83 is attached to the top of the cylindrical body 82 so as to close the upper side of the cylindrical body 82. The top plate 83 has a through-hole 84 through which the spindle 72 passes.

[0057] The cover 81 having this configuration is attached to the holder 56 of the lifting mechanism 50. Specifically, multiple (three in this embodiment) mounting mechanisms 85 are provided on the upper surface of the top plate 83 of the cover 81 and on the holder 56 of the lifting mechanism 50, for attaching the cover 81 so that it can move up and down relative to the holder 56.

[0058] As shown in Figure 3, the mounting mechanism 85 is provided on the -Y direction side and the +X direction side of the holder 56. Although not shown, the mounting mechanism 85 is also provided on the -X direction side of the holder 56.

[0059] The mounting mechanism 85 includes a slider 86 provided on the top plate 83 of the cover 81, and a guide portion (guide rail) 87 and a stopper 88 provided on the holder 56 which moves vertically together with the grinding mechanism 70.

[0060] The slider 86 has a narrow plate shape and is mounted on the top plate 83 of the cover 81 so as to extend vertically. The slider 86 is fixed to the top plate 83 so as to be able to move integrally with the cover 81. In addition, a projection 861 is formed on the side of the slider 86.

[0061] The guide portion 87 has an opening facing horizontally and a groove portion 871 extending vertically. The slider 86 is inserted into this groove portion 871 so as to be movable in the vertical direction. Therefore, the cover 81, including the slider 86, can move vertically while being guided by the guide portion 87. In other words, in the cover mechanism 80, the guide portion 87 supports the cover 81, including the slider 86, so that it can move up and down vertically. Furthermore, the projection 861 of the slider 86 protrudes horizontally from the opening of the groove 871 of the guide portion 87.

[0062] The stopper 88 is provided near the guide portion 87 in the holder 56 so as to block the lower end of the opening of the groove portion 871. As shown in Figure 4, when the cover 81 including the slider 86 descends relative to the holder 56 by its own weight and is positioned in the lower position, the stopper 88 abuts against the lower end of the projection 861 of the slider 86, thereby restricting the descent of the cover 81. As a result, as shown in Figure 4, when the cover 81 is positioned in the lower position, a gap L1 is formed between the lower surface of the top plate 83 of the cover 81 and the upper surface of the wheel mount 74 of the grinding mechanism 70.

[0063] Thus, the stopper 88 is configured to support the cover 81 such that when the cover 81 is positioned in a lower position due to its own weight, a gap L1 is formed between the lower surface of the top plate 83 and the upper surface of the wheel mount 74.

[0064] The cover 81, which is attached to the holder 56 by such a mounting mechanism 85, can move vertically relative to the holder 56 within a range limited by the stopper 88. Furthermore, the cover 81 can move vertically together with the holder 56 and the grinding mechanism 70 by the lifting mechanism 50, with the projection 861 of the slider 86 in contact with the stopper 88. In other words, the stopper 88 supports the cover 81 so that it can move vertically together with the holder 56 and the grinding wheel 77.

[0065] Furthermore, as shown in Figures 1 and 2, the cover mechanism 80 includes a cylindrical positioning block 90 on the Y-axis movement table 45 of the Y-axis movement mechanism 40. The positioning block 90 is not limited to a cylindrical shape; it may also have other shapes, such as a rectangular prism shape.

[0066] The positioning block 90 is positioned on the Y-axis moving table 45 at the +X and +Y direction side of the chuck table 20, penetrating the flat plate 39 and adjacent to the chuck table 20, and has an upper surface 901 at the same height as the holding surface 22. This positioning block 90 contacts the lower end of the cover 81 (the lower end of the cylindrical body 82) that has descended together with the holder 56 and the grinding mechanism 70, and is intended to support the lower end of the cover 81.

[0067] As the holder 56 and grinding mechanism 70 are lowered, the lower end of the cover 81, which is also lowering, comes into contact with the upper surface 901 of the positioning block 90 and rests on the positioning block 90, thereby stopping the lowering of the cover 81. As a result, the slider 86 of the cover 81 rises within the guide portion 87 (see Figure 3), and the cover 81 rises relative to the holder 56 and grinding mechanism 70, which are still descending. In other words, the positioning block 90 raises the cover 81 relative to the grinding wheel 77 by the guide portion 87.

[0068] As a result, the positioning block 90 positions the cover 81 at a predetermined height relative to the holding surface 22 of the chuck table 20 when the wafer 100 is being ground with the grinding wheel 77, as shown in Figure 2. Consequently, the cover 81, together with the holding surface 22 and the bottom plate 91 (described later), forms a space S1 surrounding the grinding wheel 77 that is in contact with the back surface 102 of the wafer 100.

[0069] The predetermined height of the cover 81 is an appropriate height that allows the cover 81, together with the retaining surface 22 and the bottom plate 91, to form a space S1 which is substantially closed (a space in which substantially no leakage occurs during suction).

[0070] Furthermore, in this embodiment, the positioning blocks 90 are provided at two locations near the chuck table 20, as shown in Figure 5. Figure 5 is a view from above of the area near the cover 81 and the chuck table 20, positioned at a predetermined height, and is a view along the line AA in Figure 2. In this figure, the top plate 83 of the cover 81 is omitted. The bottom plate 91 is indicated by hatching. Furthermore, the number of positioning blocks 90 is not limited to two; it may be one, three or more, or any number of blocks.

[0071] Furthermore, the cover mechanism 80 has a bottom plate 91, as shown in Figure 2. The bottom plate 91 is, for example, detachably connected to the lower end of the cylindrical body 82 in the cover 81. The bottom plate 91 is configured to cover the lower surface of the portion of the cover 81 that protrudes from the chuck table 20 when it is positioned at a predetermined height by the positioning block 90, as shown in Figure 5. That is, the bottom plate 91 has a disc-like shape with a portion cut out to avoid contact with the chuck table 20 and the positioning block 90 located at the machining position 302 when the cover 81 is positioned at a predetermined height.

[0072] Furthermore, as shown in Figure 2, the cover mechanism 80 is equipped with a plurality of cleaning water nozzles 92 on the bottom plate 91. The cleaning water nozzles 92 spray cleaning water onto the underside of the grinding wheel 77 and are connected to the cleaning water source 203 via a cleaning water valve 93. By communicating with the cleaning water source 203, the cleaning water nozzles 92 are configured to spray cleaning water onto the underside of the portion of the grinding wheel 77 that extends beyond the chuck table 20.

[0073] Furthermore, as shown in Figure 3, the cover mechanism 80 is provided with a suction passage 95 on the outer surface of the cylindrical body 82 that communicates with the inside of the cylindrical body 82 (the inside of the cover 81). The suction passage 95 is a passage for sucking up the spray and grinding water in the space S1 formed by the cover 81, the holding surface 22, and the bottom plate 91, and has a suction port 951 at its tip. This suction port 951 is connected to the spray suction source 202 via a spray suction valve 96. In the cover mechanism 80, the suction port 951 is connected to the spray suction source 202, so that the space S1 is connected to the spray suction source 202 via the suction passage 95, making it possible to suction the spray and grinding water in the space S1. A gas-liquid separation mechanism may be provided between the suction port 951 and the spray suction source 202.

[0074] The control unit 7 of the grinding apparatus 1 shown in Figure 1 includes a CPU that performs calculations according to a control program, and a storage medium such as memory. For example, the control unit 7 controls each of the above-mentioned components of the grinding apparatus 1 to perform grinding, in which the wafer 100 held in the chuck table 20 is ground with the grinding wheel 77.

[0075] Furthermore, in order to maintain the upper surface of the chuck table 20 in a normal state, the control unit 7 performs self-grinding, for example, periodically, by grinding the upper surface of the chuck table 20 with the holding surface grinding wheel 177.

[0076] First, the self-grinding according to this embodiment will be described. In self-grinding, the operator first attaches the retaining surface grinding wheel 175, which includes the retaining surface grinding wheel 177, to the wheel mount 74. At this time, the operator attaches and detaches the bottom plate 91 of the cover mechanism 80 to the cover 81 as appropriate. Then, the control unit 7 grinds the upper surface of the chuck table 20 with the retaining surface grinding wheel 177.

[0077] Specifically, the control unit 7 controls the Y-axis movement mechanism 40 shown in Figure 1 to position the wafer holding mechanism 30, including the chuck table 20, at the processing position 302. This positions the grinding wheel 177 for grinding the holding surface of the grinding mechanism 70 so that it passes through the center of the holding surface 22.

[0078] Then, the control unit 7 rotates the grinding wheel 177 for holding surface grinding and the chuck table 20 of the grinding mechanism 70, while lowering the grinding mechanism 70 using the lifting mechanism 50, bringing the grinding wheel 177 into contact with the holding surface 22 and the frame surface 24, which are the upper surfaces of the chuck table 20, and grinding the holding surface 22 and the frame surface 24 with the grinding wheel 177. As a result, the holding surface 22 and the frame surface 24 are brought into an appropriate state. That is, the holding surface 22 becomes parallel to the lower surface of the grinding wheel 77, and the frame surface 24 becomes flush with the holding surface 22.

[0079] Subsequently, in this embodiment, the control unit 7, for example, while maintaining the height of the grinding wheel 177 used to grind the holding surface 22 and the frame surface 24, controls the Y-axis movement mechanism 40 to move the positions of the chuck table 20 and the Y-axis movement table 45 toward the -Y direction, thereby bringing the lower surface of the grinding wheel 177 into contact with the upper surface 901 (see Figure 2) of the positioning block 90 adjacent to the chuck table 20, and grinding this upper surface 901. As a result, the upper surface 901 of the positioning block 90 is ground to the same height as the holding surface 22. Furthermore, a lifting mechanism may be provided to raise and lower the positioning block 90, and the height of the upper surface 901 of the positioning block 90 may be adjusted so that the chuck table 20 is at the same height as the holding surface 22 after self-grinding.

[0080] Next, the wafer grinding operation according to this embodiment will be described.

[0081] [Holding process] In the grinding operation, first, the operator attaches the grinding wheel 75, which includes the grinding wheel 77, to the wheel mount 74 of the grinding mechanism 70. Next, for example, the operator or a transport device (not shown) places the wafer 100 on the holding surface 22 of the chuck table 20, which is located at the holding position 301 shown in Figure 1, with the back surface 102 facing upwards. Then, the control unit 7 opens the suction on / off valve 632 shown in Figure 2, connecting the suction source 63 to the holding surface 22 of the chuck table 20. As a result, the wafer 100 is held by the holding surface 22.

[0082] [Grinding process] Next, the control unit 7 controls the Y-axis movement mechanism 40 shown in Figure 1 to position the wafer holding mechanism 30, including the chuck table 20, at the processing position 302. As a result, as shown in Figure 4, the grinding wheel 77 of the grinding mechanism 70 is positioned to pass through the center of the wafer 100 held on the holding surface 22.

[0083] At this time, the holder 56 of the lifting mechanism 50 and the grinding mechanism 70 are positioned at a relatively high raised position 303. The cover 81 is lowered relative to the holder 56 by its own weight and is supported by the stopper 88 via the slider 86 and projection 861 such that a gap L1 is formed between the lower surface of the top plate 83 and the upper surface of the wheel mount 74.

[0084] Subsequently, the control unit 7 rotates the spindle 72 and grinding wheel 77 of the grinding mechanism 70 using the spindle motor 73, and rotates the chuck table 20 holding the wafer 100 using the rotation mechanism 32.

[0085] Furthermore, at this time, the control unit 7 opens the grinding water valve 78 to supply grinding water from the grinding water source 201 to the grinding wheel 77 via the grinding water channel 79.

[0086] Furthermore, the control unit 7 lowers the holder 56 and the grinding mechanism 70 using the lifting mechanism 50. As a result, as shown in Figure 2, the holder 56 and the grinding mechanism 70 are positioned at a relatively low grinding position 304, and the grinding wheel 77 of the grinding mechanism 70 comes into contact with the back surface 102 of the wafer 100 held in the chuck table 20.

[0087] Furthermore, as the holder 56 and grinding mechanism 70 are lowered and reach the grinding position 304, the lower end of the cylindrical body 82 of the cover 81, which was lowering along with them, rests on the upper surface 901 of the positioning block 90 provided on the Y-axis moving table 45, and the lowering of the cover 81 stops. As a result, the slider 86 of the cover 81 rises within the guide section 87, and the cover 81 rises relative to the holder 56 and grinding mechanism 70, which are still lowering.

[0088] As a result, the cover 81 is positioned at a predetermined height relative to the holding surface 22 of the chuck table 20, and together with the bottom plate 91 provided at the bottom of the cover 81 and the holding surface 22, it forms a closed space S1 that surrounds the grinding wheel 77 in contact with the back surface 102 of the wafer 100.

[0089] In this state, the control unit 7 grinds the back surface 102 of the wafer 100 with the rotating grinding wheel 77. At this time, a spray of grinding water containing grinding debris is generated, but because a closed space S1 is formed surrounding the grinding wheel 77, the spray is prevented from being ejected outside the space S1.

[0090] Furthermore, during the grinding process, the control unit 7 opens the spray suction valve 96, connecting the suction port 951 of the suction passage 95 to the spray suction source 202. This allows the spray containing grinding debris and grinding water in the space S1 to be properly sucked up and discharged from the space S1.

[0091] Furthermore, during the grinding process, the control unit 7 opens the cleaning water valve 93 and connects the cleaning water nozzle 92 provided on the bottom plate 91 of the cover 81 to the cleaning water source 203, thereby supplying cleaning water to the underside of the portion of the grinding wheel 77 that extends beyond the chuck table 20, and cleaning the grinding wheel 77. The cleaning water used in this cleaning is discharged to the outside of space S1 via the suction passage 95 along with the grinding water.

[0092] Furthermore, during the grinding process, the control unit 7 uses a thickness measuring instrument 67 to measure the thickness of the wafer 100 being ground. The control unit 7 then terminates the grinding process when the thickness of the wafer 100 reaches a predetermined thickness.

[0093] [Recovery Process] When the thickness of the wafer 100 reaches a predetermined thickness, the control unit 7 raises the holder 56 and the grinding mechanism 70 to the raised position 303 using the lifting mechanism 50, as shown in Figure 4, and stops the rotation of the grinding wheel 77 and the chuck table 20. Furthermore, the control unit 7 closes the grinding water valve 78 and the cleaning water valve 93 to stop the supply of grinding water and cleaning water, and closes the spray suction valve 96 to stop spraying and sucking of grinding water. Then, the control unit 7 positions the wafer holding mechanism 30, including the chuck table 20, at the holding position 301 using the Y-axis movement mechanism 40 (see Figure 1).

[0094] Furthermore, the control unit 7 closes the suction valve 632 shown in Figure 4, blocking communication between the suction source 63 and the holding surface 22. In addition, the control unit 7 opens, for example, the air supply valve 642 and the water supply valve 652, connecting the holding surface 22 to the air supply source 64 and the water supply source 65, and ejecting a mixed fluid of air and water (two fluids) from the holding surface 22. As a result, the wafer 100 is separated from the holding surface 22 and can be recovered by an operator or a transport device (not shown).

[0095] As described above, in this embodiment, the cover 81, its bottom plate 91, and the holding surface 22 of the chuck table 20 can form a closed space S1 surrounding the grinding wheel 77 that is grinding the back surface 102 of the wafer 100. Therefore, by connecting the spray suction source 202 to space S1 via the suction passage 95, the spray containing grinding debris and grinding water in space S1 can be effectively sucked up with virtually no leakage. Consequently, contamination of external components and processing chambers of space S1 in the grinding apparatus 1 by these sprays and grinding water can be suppressed.

[0096] Furthermore, in this embodiment, a positioning block 90 is provided that contacts the lower end of the cylindrical body 82 in the cover 81 to adjust the height of the cover 81 in order to position the cover 81 at a predetermined height suitable for forming a closed space S1. Therefore, the cover 81 can be easily positioned at a predetermined height. As a result, the cover 81, bottom plate 91 and holding surface 22 can easily form a closed space S1 surrounding the grinding wheel 77. This allows the spray and grinding water containing grinding debris generated by grinding to be effectively sucked out of the space S1 by the suction passage 95 and spray suction source 202.

[0097] In this embodiment, the height of the holding surface 22 of the chuck table 20 is reduced as the holding surface 22 is ground by the holding surface grinding wheel 177 during self-grinding. When the height of the holding surface 22 is reduced, the predetermined height of the cover 81, which is suitable for creating a closed space S1, is also reduced. Therefore, when forming space S1 in the grinding process, it is necessary to lower the cover 81 and the bottom plate 91 to match the height of the holding surface 22.

[0098] In this regard, in this embodiment, the upper surface 901 of the positioning block 90, which the cover 81 contacts when the space S1 is formed, is ground during self-grinding so that it is the same height as the holding surface 22 of the chuck table 20, and the height of this upper surface 901 is reduced in the same way as the holding surface 22.

[0099] Therefore, in this embodiment, even if the height of the holding surface 22 is reduced, the height of the cover 81 and the bottom plate 91 connected to the cover 81 can be reduced in the same way, so that the cover 81, the bottom plate 91 and the holding surface 22 can easily form a closed space S1 surrounding the grinding wheel 77. For this reason, even if the height of the holding surface 22 is reduced, the spray containing grinding debris and grinding water generated by grinding can be effectively sucked out of the space S1 by the suction passage 95 and the spray suction source 202.

[0100] Furthermore, in this embodiment, during the grinding process, the cleaning water nozzle 92 is connected to the cleaning water source 203 to supply cleaning water to the underside of the portion of the grinding wheel 77 that extends beyond the chuck table 20, thereby cleaning the grinding wheel 77. That is, in addition to the grinding water from the grinding water channel 79, cleaning water from the cleaning water nozzle 92 is supplied to the underside of the grinding wheel 77. This makes it possible to more effectively clean and cool the underside of the grinding wheel 77 during the grinding process. As a result, clogging of the underside of the grinding wheel 77 can be suppressed, and grinding defects can be prevented.

[0101] In the cover mechanism 80, the bottom plate 91 does not necessarily have to be connected to the cylindrical body 82 of the cover 81. The bottom plate 91 may be provided in a location near the chuck table 20 (for example, a flat plate 39) so as to cover the lower surface of the portion of the cover 81 that protrudes from the chuck table 20, which is positioned at a predetermined height by the positioning block 90.

[0102] Furthermore, when grinding the holding surface 22 and frame surface 24, which are the upper surfaces of the chuck table 20, during self-grinding, the holding surface grinding wheel 177 may have a larger diameter than the grinding wheel 77 so that the upper surface 901 of the positioning block 90 can be properly ground.

[0103] Furthermore, in this embodiment, the positioning block 90 is provided on the Y-axis moving table 45 of the Y-axis moving mechanism 40. In this regard, the positioning block 90 may also be provided on the support member 28 of the wafer holding mechanism 30, or on the flat plate 39 in the opening 13 of the base 10.

[0104] Furthermore, in this embodiment, the grinding apparatus 1 has a wafer holding mechanism 30 including a chuck table 20, and this wafer holding mechanism 30 is moved between a holding position 301 on the -Y direction side and a processing position 302 on the +Y direction side by the Y-axis movement mechanism 40 shown in Figure 1. In this regard, the wafer holding mechanism 30 may have a plurality of wafer holding mechanisms 30 and a turntable that holds and rotates the plurality of wafer holding mechanisms 30. In this configuration, the wafer holding mechanism 30 is moved between a holding position and a processing position by the rotation of the turntable. In this case, the positioning block 90 may be provided on the turntable. [Explanation of Symbols]

[0105] 1: Grinding device, 7: Control unit, 10: Base, 11: Column, 12: Bellows cover, 13: Opening, 20: Chuck table, 21: Porous member, 22: Holding surface, 23: Frame, 24: Frame surface, 27: Support column, 28: Support member, 29: Chuck table base, 30: Wafer holding mechanism, 31: Support mechanism, 32: Rotating mechanism, 33: Motor, 34: Drive pulley, 35: Endless belt, 36: Driven pulley, 39: Flat plate, 40: Y-axis movement mechanism, 41: Holding base, 42: Y-axis guide rail, 43: Y-axis ball screw, 44: Y-axis motor, 45: Y-axis moving table, 50: Lifting mechanism, 51: Z-axis guide rail, 52: Z-axis ball screw, 53: Z-axis moving table, 54: Z-axis motor, 55: Z-axis encoder, 56: holder, 57: sliding member, 58: nut part, 60: Fluid flow mechanism, 61: Suction channel, 62: Rotary joint, 63: Suction source, 64: Air supply source, 65: Water supply source, 67: Thickness measuring instrument, 68: Wafer height measuring unit, 69: Holding surface height measuring section, 70: Grinding mechanism, 71: Spindle housing, 72: Spindle, 73: Spindle motor, 74: Wheel mount, 75: Grinding wheel, 76: Wheel base, 77: Grinding wheel, 78: Grinding water valve, 79: Grinding water channel, 80: Cover mechanism, 81: Cover, 82: Cylindrical body, 83: Top plate, 84: Through-hole, 85: Mounting mechanism, 86: Slider, 87: Guide section, 88: Stopper, 90: Positioning block, 91: Base plate, 92: Washing water nozzle, 93: Washing water valve, 95: Suction path, 96: Spray suction valve, 100: Wafer, 101: Front surface, 102: Back surface, 175: Wheel for grinding the holding surface, 176: Wheel base, 177: Grinding wheel for holding surface grinding, 201: Grinding water source, 202: Spray suction source, 203: Washing water source, 301: Holding position, 302: Processing position, 303: Lifting position, 304: Grinding position, 491: Water piping, 601: Arrow, 631: Suction piping, 632: Suction shut-off valve, 641: Air piping, 642: Air supply shut-off valve, 652: Water supply shut-off valve, 861: Projection, 871: Groove, 901: Top surface, 951: Suction port, L1: Gap, S1: Space

Claims

1. A chuck table that holds and rotates the wafer using a holding surface, A grinding mechanism that rotates an annular grinding wheel mounted on a mount positioned at the tip of a spindle, and brings the lower surface of the grinding wheel into contact with a wafer held on the holding surface to grind the wafer, A lifting mechanism for moving the grinding mechanism in the vertical direction, A grinding apparatus comprising a grinding water supply unit that supplies grinding water to the grinding wheel, The chuck table is equipped with a cover mechanism that surrounds the grinding wheel during grinding, The cover mechanism is, A cylindrical body surrounding the outer surface of the grinding wheel mounted on the mount, and a cover including a top plate that has a through-hole through which the spindle passes and closes the top of the cylindrical body, A guide section that supports the cover so that it can move up and down vertically, A stopper that supports the cover such that a gap is formed between the lower surface of the top plate and the upper surface of the mount when the cover is positioned in a lower position due to its own weight, A positioning block that, when the grinding mechanism is lowered by the lifting mechanism, places the lower end of the cover on it, raises the cover relative to the grinding wheel by the guide portion, and positions the cover at a predetermined height relative to the holding surface of the chuck table while the wafer is being ground with the grinding wheel, It comprises a bottom plate that covers the underside of the portion of the cover that protrudes from the chuck table, which is positioned at a predetermined height, Grinding device.

2. The bottom plate is equipped with a cleaning water nozzle that sprays cleaning water onto the underside of the grinding wheel. The grinding apparatus according to claim 1.

Images