Spindle unit

Abstract

To achieve downsizing in an axial direction of a spindle.SOLUTION: A spindle unit (31) includes: a spindle (32) connected at a tip with a wheel mount (50) to which a grinding stone (53) is attached; a casing (34) rotatably supporting the spindle on a radial air bearing (RB); and an air cylinder (70) which is arranged in the spindle and in which a piston (72) moves forward and backward. The spindle unit (31) further includes: a forward joint (FJ) joining a first casing side air flow passage (81) and a first spindle side air flow passage (91); and a backward joint (BJ) joining a second casing side air flow passage (82) and a second spindle side air flow passage (92). Each of the joints is arranged in the casing and the spindle in portions where the radial air bearing is formed.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a spindle unit having a spindle on which a processing tool is attached. [Background technology]

[0002] Known grinding devices for grinding wafers are configured to selectively protrude two concentric processing tools (a grinding wheel and a polishing pad) to process wafers, as disclosed in Patent Documents 1 and 2, for example. Patent Document 2 discloses an air cylinder that moves the polishing pad relative to the grinding wheel in the axial direction of the spindle to protrude either the grinding wheel or the polishing pad. Air is supplied to the air cylinder via a rotary joint that communicates with an air supply source. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Laid-Open No. 2011-131291 [Patent Document 2] Japanese Patent Application Publication No. 2018-192533 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 2, the rotary joint is connected to the upper end of the spindle. Therefore, the rotary joint is located above the casing of the spindle unit, which increases the vertical width of the spindle unit and results in an increase in size. In addition, by locating the rotary joint above the casing, the center of gravity of the spindle unit is shifted upward, which reduces stability and affects machining accuracy.

[0005] The present invention has been made in view of the above points, and one of its objects is to provide a spindle unit that can be made smaller in size in the axial direction of the spindle. [Means for solving the problem]

[0006] a first forward air supply passage disposed in the casing for advancing the piston; a second forward air supply passage disposed at least in the spindle for advancing the piston; an advance joint disposed on the casing at a portion where the air bearing is formed and on the spindle, connecting the first forward air supply passage and the second forward air supply passage; a first backward air supply passage disposed in the casing for retracting the piston; a second backward air supply passage disposed at least in the spindle for retracting the piston; and a backward joint disposed on the casing at a portion where the air bearing is formed and on the spindle, connecting the first backward air supply passage and the second backward air supply passage. [Effects of the Invention]

[0007] According to the present invention, the joints are located in the area where the air bearings are formed, so that no joints are located at the ends of the spindle. This prevents the joints from protruding from the casing in the axial direction of the spindle, making it possible to reduce the size of the entire unit. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a schematic perspective view of a grinding device according to an embodiment. [Figure 2] FIG. 2 is a cross-sectional view showing the configuration of a spindle unit. [Figure 3] FIG. 3 is a partially enlarged view of FIG. 2 for explaining an air bearing. [Figure 4]FIG. 3 is a partially enlarged view of FIG. 2 for explaining an advance joint and a retreat joint. [Figure 5] FIG. 5 is an enlarged view similar to FIG. 4, but with the grinding wheel removed. [Figure 6] FIG. 3 is a cross-sectional view similar to FIG. 2 showing a state in which a part of the configuration of the spindle unit has been replaced. [Figure 7] FIG. 7 is a partial enlarged view of FIG. 6 for explaining an advance joint and a retreat joint. [Figure 8] FIG. 8 is an enlarged view similar to FIG. 7, showing the second grinding wheel retracted. [Figure 9] FIG. 10 is a plan view illustrating a second attachment / detachment mechanism. [Figure 10] FIG. 10 is an explanatory exploded cross-sectional view of a second attachment / detachment mechanism. DETAILED DESCRIPTION OF THE INVENTION

[0009] Hereinafter, a grinding device according to an embodiment will be described with reference to the accompanying drawings. FIG. 1 is a schematic perspective view of a grinding device according to an embodiment. Note that the present invention is not limited to the following embodiment, and can be practiced with appropriate modifications within the scope of the present invention. For the sake of convenience of explanation, some components may be omitted in the following drawings.

[0010] The X-axis, Y-axis, and Z-axis directions of the grinding apparatus 1 are perpendicular to one another. The X-axis and Y-axis directions are approximately horizontal, and the Z-axis direction is an up-down direction (vertical direction). Of the two arrows indicating the X-axis direction, the +X side is the front and the -X side is the rear. Of the two arrows indicating the Z-axis direction, the +Z side is the up and the -Z side is the down.

[0011] 1, a rectangular opening extending in the X-axis direction is formed on the upper surface of a base 10 of the grinding device 1. This opening is covered by a movable plate 13 that is movable in the X-axis direction together with a chuck table 12, and a bellows-shaped waterproof cover 14.

[0012] The chuck table 12 is equipped with a circular porous plate 15. The porous plate 15 is made of a porous material such as ceramics, and has fine pores formed throughout. The upper surface of the porous plate 15 constitutes a holding surface 16. The holding surface 16 holds a wafer (workpiece) W by suction using a suction source (not shown).

[0013] In this embodiment, the wafer W is formed in a substantially circular disk shape. The wafer W to be processed may be any plate-shaped workpiece to be ground, and may be a semiconductor substrate such as silicon or gallium arsenide, an inorganic material substrate such as ceramic, glass, or sapphire, or even a package substrate for a semiconductor product.

[0014] In the grinding process, the lower surface W2 of the wafer W serves as a held surface that is sucked and held by the holding surface 16 of the chuck table 12, and the upper surface W1 of the wafer W serves as a ground surface that is ground. A protective tape may be attached to the lower surface W2 of the wafer W.

[0015] A table moving mechanism and a table rotating mechanism (neither of which are shown) are provided inside the base 10 and below the moving plate 13 and the waterproof cover 14. The table moving mechanism moves the chuck table 12 in the X-axis direction, and the table rotating mechanism rotates the chuck table 12 around a central axis parallel to the Z-axis direction. A thickness measuring device 17 for measuring the thickness of the wafer W held on the chuck table 12 is installed on the base 10 at a position through which the chuck table 12 passes.

[0016] The thickness measuring device 17 includes a first height gauge that measures the height position of the upper surface W1 of the wafer W held on the holding surface 16 of the chuck table 12, and a second height gauge that measures the height position of the upper surface of the chuck table 12. The thickness measuring device 17 measures the thickness of the wafer W based on the difference between the measurement value of the first height gauge and the measurement value of the second height gauge.

[0017] The grinding device 1 further includes a lifting unit 20 and a grinding unit 30. The lifting unit 20 is provided on a column 18 erected at the rear of the base 10, and moves the grinding unit 30 up and down in the Z-axis direction.

[0018] The lifting unit 20 comprises a pair of guide rails 21 arranged on the front side of the column 18 and extending in the Z-axis direction, a lifting table 22 installed so as to be movable in the Z-axis direction relative to the pair of guide rails 21, and a ball screw 23 extending in the Z-axis direction and screwed into a screw-threaded portion (not shown) of the lifting table 22.

[0019] A motor 24 is connected to one end of the ball screw 23. In the lifting unit 20, the ball screw 23 is rotated by the driving force of the motor 24, causing the lifting table 22 and the grinding unit 30 to move up and down in the Z-axis direction. An encoder 26 that detects the number of rotations (number of pulses) is provided on the motor 24, and the amount of movement of the lifting table 22 and the grinding unit 30 can be obtained from the pulse signal output from the encoder 26.

[0020] The grinding unit 30 includes a spindle unit 31 attached to the front surface of the lift table 22 via a holder 25, and the spindle unit 31 will be described later. The grinding unit 30 also includes a plurality of grinding wheels (processing tools) 53 attached to the lower portion (tip end side) of a spindle 32 of the spindle unit 31. The grinding unit 30 rotates the attached annular grinding wheels 53 by the spindle 32, and grinds the upper surface W1 of the wafer W held by suction on the holding surface 16 of the chuck table 12.

[0021] The operation of each part of the grinding apparatus 1 is controlled by a control unit 19. The control unit 19 is configured to include a processor that executes various processes, as well as a storage unit (memory) that stores various parameters, programs, etc. The storage unit of the control unit 19 stores, as part of the control program, programs for controlling the operation of the lifting unit 20, the grinding unit 30, the solenoid valve V (described later), etc. Unless a control entity is specified for the operation of each part of the grinding apparatus 1 described below, it is assumed that the operation is controlled by a control signal sent from the control unit 19.

[0022] 2 is a cross-sectional view showing the configuration of the spindle unit. Note that hatching indicating a cross section of each component is omitted in the cross-sectional views from FIG. 2 onwards.

[0023] As shown in FIG. 2, the spindle unit 31 includes an upright spindle 32, a casing 34 that covers and supports the spindle 32, and a spindle cover 36 that covers the lower end portion of the spindle 32.

[0024] The spindle 32 is disposed so as to extend in the Z-axis direction, which is the direction of the rotation center C shown in Fig. 2. A large-diameter first circular plate portion 321 is formed in the middle portion of the spindle 32. In addition, a large-diameter second circular plate portion 322 is also formed in the lower end portion of the spindle 32.

[0025] A rotary motor 40 is connected to the upper end of the spindle 32. The rotary motor 40 has a rotor 41 and a stator 42 provided at the upper end portion of the spindle 32. When a predetermined voltage is applied to the stator 42, the rotor 41 rotates, and the spindle 32 rotates around its center of rotation C.

[0026] The stator 42 is mounted on the inner circumferential surface of the casing 34 via a cooling jacket 45. A large number of cooling water passages 46 are formed in the cooling jacket 45. The rotary motor 40 is cooled by these cooling water passages 46.

[0027] A wheel mount (mount) 50 is connected to the tip (lower end) of the spindle 32. The wheel mount 50 is formed in a disk shape and is fixed to the tip of the spindle 32. A grinding wheel 51 is attached to the wheel mount 50.

[0028] The grinding wheel 51 is formed so that its outer diameter is approximately the same as the outer diameter of the wheel mount 50. The grinding wheel 51 includes an annular wheel base 52 made of a metal material. A plurality of grinding stones 53, each having an approximately rectangular parallelepiped shape, are arranged in an annular pattern around the entire circumference of the underside of the wheel base 52. The grinding wheel 51 including the grinding stones 53 is attached to the wheel mount 50.

[0029] The grinding wheel 53 is an example of a processing tool for processing the wafer W (see FIG. 1), and is rotated by the rotation motor 40 via the spindle 32, the wheel mount 50, and the wheel base 52. This allows the grinding wheel 53 to grind the wafer W held on the chuck table 12 (see FIG. 1).

[0030] A grinding water inlet passage 56, which is connected to a grinding water source 55, is attached to the upper end of the spindle 32. The grinding water inlet passage 56 is also connected to a grinding water passage 57 provided in the spindle 32, the wheel mount 50, and the wheel base 52. With this structure, grinding water from the grinding water source 55 is supplied to the grinding wheel 53 via the grinding water inlet passage 56 and the grinding water passage 57. As a result, during grinding, the grinding wheel 53 and the wafer W are cooled by the grinding fluid, and grinding chips are washed away from the upper surface W1 of the wafer W together with the grinding fluid.

[0031] The casing 34 has, for example, a substantially cylindrical shape, and is configured so that the spindle 32, the rotary motor 40, etc. are disposed therein. The top of the casing 34 is closed by a lid member 35. The casing 34 is configured to surround the spindle 32 and rotatably support the spindle 32 by a radial air bearing RB (air bearing) and a thrust air bearing TB (air bearing).

[0032] The casing 34 has an annular portion 341 at its lower end portion. The annular portion 341 is provided so as to fit between the first circular plate portion 321 and the second circular plate portion 322 of the spindle 32, and so as to form small gaps between the annular portion 341 and the first circular plate portion 321 and the second circular plate portion 322.

[0033] Fig. 3 is an enlarged view of the +X side of the annular portion 341 and its vicinity in the casing 34 shown in Fig. 2. As shown in Fig. 3, a first air supply passage 63 is formed so as to extend from the outside of the spindle unit 31 to the inside of the annular portion 341 in the casing 34. The first air supply passage 63 is connected to the air supply source 60 via an air intake port 61.

[0034] The casing 34 also has radial-side air outlets 342 in its annular portion 341 that constitute the radial air bearing RB. The radial-side air outlets 342 are connected to the first air supply passage 63. The radial-side air outlets 342 are provided in a radial-side casing surface 343 that extends in the Z-axis direction of the annular portion 341 of the casing 34. The radial-side air outlets 342 are also provided so as to face a radial-side spindle surface 323 that extends between the first circular plate portion 321 and the second circular plate portion 322 of the spindle 32. The radial-side spindle surface 323 of the spindle 32 is a part (portion) that forms the radial air bearing RB in the spindle 32. The radial-side casing surface 343 of the casing 34 is also a part (portion) that forms the radial air bearing RB in the casing 34.

[0035] The radial-side air outlet 342 opens toward a radial gap 37, which is the gap between a radial-side spindle surface 323 of the spindle 32 and a radial-side casing surface 343 of the casing 34. High-pressure air supplied from the first air supply passage 63 is ejected from the radial-side air outlet 342 in the horizontal direction, which is the radial direction, toward the radial gap 37. As a result, a radial air bearing RB is formed in the radial gap 37 between the casing 34 and the spindle 32, which supports the spindle 32 in a non-contact manner by air while allowing the spindle 32 to rotate.

[0036] Furthermore, a second air supply passage 64 connected to the first air supply passage 63 is formed inside the annular portion 341. The casing 34 is provided with thrust-side air outlets 345 that constitute thrust air bearings TB in the annular portion 341. The thrust-side air outlets 345 are connected to the second air supply passage 64. The thrust-side air outlets 345 are provided on two thrust-side casing surfaces 346, which are the upper and lower surfaces of the annular portion 341 of the casing 34. The thrust-side air outlets 345 are also provided so as to face the lower surface 325 of the first circular plate portion 321 and the upper surface 326 of the second circular plate portion 322 of the spindle 32.

[0037] The thrust-side air outlet 345 opens toward a thrust gap 38, which is a gap between a lower surface 325 of the first circular plate portion 321 and an upper surface 326 of the second circular plate portion 322 of the spindle 32, and two thrust-side casing surfaces 346 of the casing 34. High-pressure air supplied from the second air supply path 64 is ejected from the thrust-side air outlet 345 toward the thrust gap 38 in the Z-axis direction, which is the thrust direction. As a result, a thrust air bearing TB is formed in the thrust gap 38 between the casing 34 and the spindle 32, which supports the spindle 32 in a non-contact manner by air while allowing the spindle 32 to rotate.

[0038] In this way, in the spindle unit 31, the spindle 32, which has a grinding wheel 53, a processing tool, attached to its tip, is surrounded by the casing 34, thereby forming a thrust air bearing TB and a radial air bearing RB between the outer surface of the spindle 32 and the inner surface of the casing 34, and supporting the spindle 32 rotatably.

[0039] The casing 34 also has a radial-side intake port 348 on the radial-side casing surface 343 of the annular portion 341, the radial-side intake port 348 being open toward the radial gap 37. The radial-side intake port 348 is connected to a first exhaust passage 65 indicated by a dashed line. The first exhaust passage 65 is provided to extend into the annular portion 341 and is connected to an exhaust port 66 provided on the surface of the annular portion 341. The radial-side intake port 348, the first exhaust passage 65, and the exhaust port 66 are used to exhaust air from the radial gap 37.

[0040] Furthermore, the casing 34 is provided with a thrust-side intake port 349 that is open toward the thrust gap 38, on the thrust-side casing surface 346 of the annular portion 341. The thrust-side intake port 349 is connected to a second exhaust passage 68 indicated by a dashed line. The second exhaust passage 68 is provided to extend into the annular portion 341 and is connected to the exhaust port 66. The thrust-side intake port 349, the second exhaust passage 68, and the exhaust port 66 are used to exhaust air from the thrust gap 38.

[0041] Returning to FIG. 2, the spindle unit 31 includes an air cylinder 70 disposed on the spindle 32, which moves a piston 72 back and forth horizontally by supplying air. The air cylinder 70 includes a housing chamber 71 extending horizontally between the rotation center C and the outer peripheral surface of the spindle 32, and a piston 72 housed within the housing chamber 71 and movable horizontally. A fixed claw 74 is connected to the piston 72 of the air cylinder 70 via a connecting portion 73, and the fixed claw 74 moves in the radial direction (horizontal direction) of the wheel mount 50 as the piston 72 moves back and forth. Although two air cylinders 70, connecting portions 73, and fixed claws 74 are shown in FIG. 2, a plurality of air cylinders 70, connecting portions 73, and fixed claws 74 are provided at equal angular intervals (for example, 120°) around the circumference of the second circular plate portion 322.

[0042] The connecting portion 73 is formed in an L-shape, extending horizontally from the piston 72 and then bending and extending downward. The connecting portion 73 protrudes downward from the underside of the second circular plate portion 322 of the spindle 32 and passes through the wheel mount 50, with the lower end of the connecting portion 73 connected to the fixed claw 74. Although not shown, a groove-like or recessed movement space is formed in the second circular plate portion 322 and the wheel mount 50 so that the connecting portion 73 can move horizontally when driven by the air cylinder 70. A guide 76 is provided on the underside of the wheel mount 50 to guide the horizontal movement of the fixed claw 74.

[0043] The fixed claws 74 have inclined surfaces that come into surface contact with inclined surfaces formed on the underside of the wheel base 52 near the opening. The fixed claws 74 move radially outward and press the inclined surfaces of the fixed claws 74 against the inclined surfaces of the wheel base 52, thereby sandwiching and fixing the wheel base 52 between the fixed claws 74 and the wheel mount 50 in the Z-axis direction. As a result, the grinding wheel 53, which is a processing tool, is fixed to the wheel mount 50 by the fixed claws 74.

[0044] Fig. 4 is an enlarged view of the -X side of the annular portion 341 of the casing 34 shown in Fig. 2 and its vicinity. As shown in Fig. 4, first to sixth casing-side air flow paths 81 to 86 are arranged in the annular portion 341 of the casing 34. Here, in the portion where the casing-side air flow paths 81 to 86 are lined up vertically, the second-lowest flow path is the first casing-side air flow path 81 (first forward air supply path), and the lowest flow path is the second casing-side air flow path 82 (first retreating air supply path). The third to sixth casing-side air flow paths 83 to 86 will be described later.

[0045] A first connection port 811 is provided on the outer surface of the annular portion 341, which forms one end of the first casing-side air flow path 81. A second connection port 821 is provided on the outer surface of the annular portion 341, which forms one end of the second casing-side air flow path 82. The first connection port 811 is connected to a solenoid valve V via a first pipe line 87, and the second connection port 821 is connected to the solenoid valve V via a second pipe line 88. An air supply source 89 is connected to the solenoid valve V. The solenoid valve V switches the destination of the air supplied from the air supply source 89 to either the first casing-side air flow path 81 or the second casing-side air flow path 82, and the other of the air is opened to the atmosphere by the solenoid valve V.

[0046] A first communication port 812 is provided on the radial side casing surface 343 side, which is the other end of the first casing side air flow path 81. A second communication port 822 is provided on the radial side casing surface 343 side, which is the other end of the second casing side air flow path 82.

[0047] In addition, a first spindle side air flow path 91 (second forward air supply path) and a second spindle side air flow path 92 (second backward air supply path) are arranged in the spindle 32 to connect the storage chamber 71 of the air cylinder 70 and the radial side spindle surface 323.

[0048] The first spindle-side air flow path 91 branches off at a first branch flow path 911 that forms a ring around the rotation center C (see FIG. 2) of the spindle 32 and communicates with the inner ends (ends closer to the rotation center C) of each of the multiple housing chambers 71. The first spindle-side air flow path 91 also extends from the first branch flow path 911 and communicates with a first circumferential groove 912 that is formed in the radial-side spindle surface 323. The first circumferential groove 912 is disposed opposite the first communication port 812. This establishes a communication state between the first circumferential groove 912 and the first communication port 812 so that air can flow therebetween.

[0049] Therefore, the first circumferential groove 912 and the first communication port 812 join (connect) the first spindle-side air flow path 91 and the first casing-side air flow path 81, and the first circumferential groove 912 and the first communication port 812 form a forward joint FJ. The forward joint FJ is disposed on the radial-side casing surface 343, which is the portion of the casing 34 where the radial air bearing RB is formed, and on the radial-side spindle surface 323, which is the portion of the spindle 32 where the radial air bearing RB is formed.

[0050] The second spindle-side air flow path 92 branches off at a second branch flow path 921 that forms a ring around the rotation center C (see FIG. 2) of the spindle 32 and communicates with the outer ends (ends on the opposite side from the rotation center C) of each of the multiple housing chambers 71. The second spindle-side air flow path 92 also extends from the second branch flow path 921 and communicates with a second circumferential groove 922 that is formed in the radial-side spindle surface 323. The second circumferential groove 922 is disposed opposite the second communication port 822. This establishes a communication state between the second circumferential groove 922 and the second communication port 822 so that air can flow therebetween.

[0051] Therefore, the second circumferential groove 922 and the second communication port 822 join (connect) the second spindle-side air flow path 92 and the second casing-side air flow path 82, and the second circumferential groove 922 and the second communication port 822 form a reverse joint BJ. The reverse joint BJ is disposed on the radial-side casing surface 343, which is the portion of the casing 34 where the radial air bearing RB is formed, and on the radial-side spindle surface 323, which is the portion of the spindle 32 where the radial air bearing RB is formed.

[0052] Next, a method for attaching and detaching the grinding wheel 51 to the spindle unit 31 will be described with reference to Figures 4 and 5. Figure 5 is a cross-sectional view similar to Figure 4, but showing a state in which the grinding wheel has been removed. In Figure 4, the piston 72 of the air cylinder 70 is positioned outside the accommodation chamber 71 (in the direction opposite to the center of the spindle 32) and has advanced. In Figure 5, the piston 72 of the air cylinder 70 is positioned inside the accommodation chamber 71 (towards the center of the spindle 32) and has retracted.

[0053] 4, when the grinding wheel 51 is attached to the wheel mount 50, the solenoid valve V controls the flow of air from the air supply source 89 through the first pipe line 87 to the first casing-side air flow path 81. The air flowing into the first casing-side air flow path 81 flows through the first communication port 812 and first circumferential groove 912 that constitute the forward joint FJ, the first spindle-side air flow path 91, and into the housing chambers 71 of the air cylinders 70.

[0054] In the accommodation chamber 71, air is supplied inward (to the left in FIG. 4) from the piston 72 through the first spindle-side air flow path 91, and the pressure in the inner space of the accommodation chamber 71 increases from the piston 72, pressing the piston 72 in a direction that moves it outward from the accommodation chamber 71. As a result, a force that moves the fixed claws 74 outward acts via the connecting portion 73, and the wheel base 52 is sandwiched between the fixed claws 74 and the wheel mount 50, and the grinding wheel 51 is attached.

[0055] As described above, the first casing-side air flow path 81 is disposed in the casing 34 to advance the piston 72 of the air cylinder 70. In addition, the first spindle-side air flow path 91 is disposed in the spindle 32 to advance the piston 72.

[0056] When piston 72 advances and moves away from the outer end of housing chamber 71, air in the outer space outside piston 72 in housing chamber 71 is discharged into second spindle-side air flow path 92. The air flowing into second spindle-side air flow path 92 then flows through second circumferential groove 922, second communication port 822, second casing-side air flow path 82, and second pipe line 88, before being released to the atmosphere via solenoid valve V. Note that even if some of the air released to the atmosphere flows into radial gap 37, the function of radial air bearing RB is maintained.

[0057] On the other hand, when the grinding wheel 51 is removed from this state and used as 40, as shown in Figure 5, the solenoid valve V controls the air from the air supply source 89 to flow through the second pipe line 88 into the second casing-side air flow path 82. The air flowing into the second casing-side air flow path 82 flows through the second communication port 822 and second circumferential groove 922 that constitute the retract joint BJ, and the second spindle-side air flow path 92, and into the accommodation chambers 71 of each air cylinder 70.

[0058] In the accommodation chamber 71, air is supplied outward (to the right in FIG. 5) from the piston 72 through the second spindle-side air flow path 92, and the pressure in the space outward from the piston 72 in the accommodation chamber 71 increases, causing the piston 72 to retreat inward into the accommodation chamber 71. This causes the fixed claws 74 to retreat inward via the connecting portions 73, releasing the wheel base 52 from its fixation, and the grinding wheel 51 is removed.

[0059] As described above, the second casing-side air flow path 82 is disposed in the casing 34 to retract the piston 72 of the air cylinder 70. In addition, the second spindle-side air flow path 92 is disposed in the spindle 32 to retract the piston 72.

[0060] When piston 72 is retracted, air in the inner space of piston 72 in housing chamber 71 is discharged into first spindle-side air flow path 91. The air flowing into first spindle-side air flow path 91 then flows through first circumferential groove 912, first communication port 812, first casing-side air flow path 81, and first pipe line 87, before being released to the atmosphere via solenoid valve V. Note that even if some of the air released to the atmosphere flows into radial gap 37, the function of radial air bearing RB is maintained.

[0061] According to the above embodiment, the forward joint FJ and the reverse joint BJ are disposed in the portion where the radial air bearing RB is formed, so that the forward joint FJ and the reverse joint BJ can be housed inside the casing 34. This makes it possible to avoid arranging the joints so that they protrude from the top of the casing as in the past, and makes it possible to reduce the vertical width of the entire spindle unit 31 and achieve compactness. Furthermore, compared to the conventional configuration in which the joints protrude, the center of gravity of the spindle unit 31 can be positioned lower, improving stability during machining and suppressing vibrations, etc., and preventing machining defects from occurring.

[0062] Furthermore, the grinding wheel 51 can be attached and detached by moving the fixed claws 74 horizontally using the air cylinder 70, so that the grinding wheel 51 can be easily attached and detached, and the vertical width of the grinding unit 30 can be reduced.

[0063] Here, in the spindle unit 31 of the above embodiment, it is possible to use it by replacing a part of the configuration. For example, it is possible to replace the configuration below the upper surface of the second circular plate portion 322 of the spindle 32, which serves as a connecting surface. An example of the configuration of the spindle unit 31 after replacement is shown in Fig. 6. Fig. 6 is a cross-sectional view similar to Fig. 2, showing the state in which a part of the configuration of the spindle unit has been replaced.

[0064] 6 includes a stepped cylindrical portion 33 instead of the second circular plate portion 322 in the configuration of FIG. 2. The spindle unit 31 shown in FIG. 6 also includes an air cylinder 78 disposed in the stepped cylindrical portion 33, a circular plate mount (first mount) 581 connected to the lower end of the stepped cylindrical portion 33, and an annular mount (second mount) 582 disposed outside the circular plate mount 581 as mounts.

[0065] The stepped cylindrical portion 33 is formed in a shape having a large diameter portion 331 that is arranged inside the spindle cover 36 and has approximately the same outer diameter dimensions as the first circular plate portion 321, and a small diameter portion 332 that is connected to the lower end of the large diameter portion 331.

[0066] An upper surface 333 of the large diameter portion 331 forms a thrust gap 38 and functions as part of the thrust air bearing TB. A disk mount 581 is connected to the lower surface of the small diameter portion 332 of the stepped cylindrical portion 33. The small diameter portion 332 of the stepped cylindrical portion 33 is sized to have a diameter that allows it to pass through the inner opening of the annular mount 582 without contacting it.

[0067] The air cylinder 78 includes an annular housing chamber 781 formed in the large diameter portion 331 of the stepped cylindrical portion 33, and an annular piston 782 housed in the housing chamber 781 and movable in the vertical direction.

[0068] A shaft 783 extending in the Z-axis direction is connected to the lower surface of the annular piston 782 of the air cylinder 78. The shaft 783 is connected to the annular piston 782 and protrudes from the lower surface of the large diameter portion 331, and the lower end of the shaft 783 is fixed to the upper surface of the annular mount 582. Therefore, the annular piston 782 is connected to the annular mount 582 via the shaft 783. Although two shafts 783 are shown in FIG. 6, a plurality of shafts 783 are provided at equal angular intervals (for example, 120°) around the circumference of the annular piston 782.

[0069] A first grinding wheel 591 is attached to the underside of the disc mount 581, and a second grinding wheel 592 is attached to the underside of the annular mount 582. A plurality of first grinding stones (first processing tools) 593 are arranged in an annular shape on the first grinding wheel 591, and a plurality of second grinding stones (second processing tools) 594 are arranged in annular shape on the second grinding wheel 592. Thus, the first grinding stone 593 is attached to the disc mount 581, and the second grinding stone 594 is attached to the annular mount 582.

[0070] The first grinding wheel 593 and the second grinding wheel 594 are examples of processing tools that grind the wafer W (see FIG. 1). The first grinding wheel 593 and the second grinding wheel 594 have different sizes of abrasive grains contained therein, for example, and the wheel with the relatively larger abrasive grains performs rough grinding, while the wheel with the relatively smaller abrasive grains performs finish grinding.

[0071] Figure 7 is an enlarged view of the -X side and its vicinity of the annular portion 341 of the casing 34 shown in Figure 6. In the portion of the annular portion 341 of the casing 34 shown in Figure 7 where the first to sixth casing-side air flow paths 81 to 86 are lined up vertically, the second flow path from the top is the third casing-side air flow path 83 (first forward air supply path), and the topmost flow path is the fourth casing-side air flow path 84 (first retreating air supply path).

[0072] The fifth casing side air flow path 85 and the sixth casing side air flow path 86, which are the third and fourth from the top, are spare air flow paths, and are used, for example, for attaching and detaching the stepped cylindrical portion 33 and the second circular plate portion 322 of the spindle 32.

[0073] A third connection port 831 is provided on the outer surface of the annular portion 341, which forms one end of the third casing-side air flow path 83. A fourth connection port 841 is provided on the outer surface of the annular portion 341, which forms one end of the fourth casing-side air flow path 84. The third connection port 831 is connected to a solenoid valve V via a first pipe line 87, and the fourth connection port 841 is connected to a solenoid valve V via a second pipe line 88. The solenoid valve V switches the destination of the air supplied from the air supply source 89 to either the third casing-side air flow path 83 or the fourth casing-side air flow path 84, and the other of the air paths is opened to the atmosphere by the solenoid valve V.

[0074] A third communication port 832 is provided on the radial side casing surface 343 side, which is the other end of the third casing side air flow path 83. A fourth communication port 842 is provided on the radial side casing surface 343 side, which is the other end of the fourth casing side air flow path 84.

[0075] In addition, a third spindle side air flow path 93 (second forward air supply path) and a fourth spindle side air flow path 94 (second backward air supply path) are arranged in the spindle 32 to connect the storage chamber 781 of the air cylinder 78 and the radial side spindle surface 323.

[0076] The third spindle-side air flow path 93 branches at a third branch flow path 931 that forms a ring around the rotation center C (see FIG. 6) of the spindle 32 and communicates with multiple locations at the upper end of the accommodation chamber 781. The third spindle-side air flow path 93 also extends from the third branch flow path 931 and communicates with a third circumferential groove 932 that is formed in the radial-side spindle surface 323. The third circumferential groove 932 is disposed opposite the third communication port 832. This establishes a communication state between the third circumferential groove 932 and the third communication port 832 so that air can flow therebetween.

[0077] Therefore, the third circumferential groove 932 and the third communication port 832 join (connect) the third spindle-side air flow path 93 and the third casing-side air flow path 83, and the third circumferential groove 932 and the third communication port 832 form a forward joint FJ. The forward joint FJ is disposed on the radial-side casing surface 343, which is the portion of the casing 34 where the radial air bearing RB is formed, and on the radial-side spindle surface 323, which is the portion of the spindle 32 where the radial air bearing RB is formed.

[0078] The fourth spindle-side air flow path 94 branches off at a fourth branch flow path 941 that forms a ring around the rotation center C (see FIG. 6) of the spindle 32 and communicates with multiple locations at the lower end of the accommodation chamber 781. The fourth spindle-side air flow path 94 also extends from the fourth branch flow path 941 and communicates with a fourth circumferential groove 942 that is formed in the radial-side spindle surface 323. The fourth circumferential groove 942 is disposed opposite the fourth communication port 842. This establishes a communication state between the fourth circumferential groove 942 and the fourth communication port 842 so that air can flow therebetween.

[0079] Therefore, the fourth circumferential groove 942 and the fourth communication port 842 join (connect) the fourth spindle-side air flow path 94 and the fourth casing-side air flow path 84, and the fourth circumferential groove 942 and the fourth communication port 842 form a reverse joint BJ. The reverse joint BJ is disposed on the radial-side casing surface 343, which is the portion of the casing 34 where the radial air bearing RB is formed, and on the radial-side spindle surface 323, which is the portion of the spindle 32 where the radial air bearing RB is formed.

[0080] Next, a method for switching between the first grinding wheel 591 and the second grinding wheel 592 will be described with reference to Figures 7 and 8. Here, Figure 7 shows a state in which the annular piston 782 of the air cylinder 78 is positioned below the accommodation chamber 781 and advanced. Figure 8 shows a state in which the annular piston 782 of the air cylinder 78 is positioned above the accommodation chamber 781 and retracted.

[0081] 7, to move the annular piston 782 of the air cylinder 78 downward so that machining can be performed with the second grinding wheel 592, the solenoid valve V controls air from the air supply source 89 to flow through the first pipe 87 into the third casing-side air flow path 83. The air flowing into the third casing-side air flow path 83 flows through the third communication port 832 and third circumferential groove 932 that constitute the advance joint FJ, and the third spindle-side air flow path 93, and into the accommodation chamber 781 of the air cylinder 78.

[0082] In the accommodation chamber 781, air is supplied to the space above the annular piston 782 through the third spindle-side air flow path 93, increasing the pressure in the space above and causing the annular piston 782 to move downward. As the annular piston 782 moves, the second grinding wheel 592 moves downward relative to the first grinding wheel 591 via the shaft 783, causing the second grinding wheel 594 to protrude downward from the first grinding wheel 593. This allows the lower surface of the second grinding wheel 594 to come into contact with the upper surface W1 of the wafer W, which is the workpiece, enabling grinding.

[0083] As described above, the third casing-side air flow path 83 is disposed in the casing 34 to advance the second grinding wheel 592 including the annular piston 782 of the air cylinder 78 and the second grinding wheel 594. The third spindle-side air flow path 93 is disposed in the spindle 32 to advance the second grinding wheel 592 including the annular piston 782 and the second grinding wheel 594.

[0084] When the annular piston 782 advances, air in the space below the accommodation chamber 781 is discharged into the fourth spindle-side air flow path 94. The air flowing into the fourth spindle-side air flow path 94 then flows through the fourth circumferential groove 942, the fourth communication port 842, the fourth casing-side air flow path 84, and the second pipe line 88, before being released to the atmosphere via the solenoid valve V.

[0085] 8, to retract the annular piston 782 of the air cylinder 78 upward so that machining can be performed with the first grinding wheel 591, the solenoid valve V controls air from the air supply source 89 to flow through the second pipe 88 into the fourth casing-side air flow path 84. The air flowing into the fourth casing-side air flow path 84 flows through the fourth communication port 842 and fourth circumferential groove 942 that constitute the retraction joint BJ, and the fourth spindle-side air flow path 94, and into the accommodation chamber 781 of the air cylinder 78.

[0086] In the accommodation chamber 781, air is supplied from the annular piston 782 to the space below through the fourth spindle-side air flow path 94, causing the pressure in the space below to increase and the annular piston 782 to move upward. As the annular piston 782 moves backward, the second grinding wheel 592 moves upward relative to the first grinding wheel 591 via the shaft 783, and the first grinding wheel 593 projects downwardly from the second grinding wheel 594. This allows the lower surface of the first grinding wheel 593 to come into contact with the upper surface W1 of the wafer W, which is the workpiece, enabling grinding.

[0087] As described above, the fourth casing-side air flow passage 84 is disposed in the casing 34 for retracting the second grinding wheel 592 including the annular piston 782 of the air cylinder 78 and the second grinding wheel 592 including the second grinding stone 594. In addition, the fourth spindle-side air flow passage 94 is disposed in the spindle 32 for retracting the second grinding wheel 592 including the annular piston 782 and the second grinding stone 594.

[0088] When the piston 72 is retracted, air in the space above the accommodation chamber 781 is discharged into the third spindle-side air flow path 93. The air flowing into the third spindle-side air flow path 93 then flows through the third circumferential groove 932, the third communication port 832, the third casing-side air flow path 83, and the first pipe line 87, and is then released to the atmosphere via the solenoid valve V.

[0089] 6 to 8, the forward joint FJ and the reverse joint BJ can be disposed in the portion where the radial air bearing RB is formed, and the forward joint FJ and the reverse joint BJ can be housed inside the casing 34. This allows the vertical width of the entire spindle unit 31 to be reduced, and the center of gravity of the spindle unit 31 to be positioned downward, improving stability during machining.

[0090] In addition, the first grinding wheel 593 and the second grinding wheel 594 are moved relatively forward and backward by the air cylinder 78, so two types of grinding wheels can be used in one grinding unit 30. In addition, the grinding wheels 591, 592 can be easily attached and detached to and from the mounts 581, 582.

[0091] The present invention is not limited to the above-described embodiments, and various modifications can be made. In the above-described embodiments, the size and shape shown in the accompanying drawings are not limited to these, and can be modified as appropriate within the scope of the effects of the present invention. In addition, the present invention can be modified as appropriate within the scope of the object of the present invention.

[0092] In the above embodiment, the processing tools are grinding wheels 53, 593, 594, but this is not limited to this and may be changed to polishing pads, etc., as long as they can be attached to the spindle 32 and used for processing.

[0093] Furthermore, the air cylinders 70, 78 are not limited to being disposed on the spindle 32, and may be disposed on each of the mounts 50, 581, 582, for example. In this case, the thickness of each of the mounts 50, 581, 582 is increased, thereby shortening the vertical length of the spindle 32. In such a configuration, a first spindle-side air flow path 91 and a third spindle-side air flow path 93, which serve as the second forward air supply path, and a second spindle-side air flow path 92 and a fourth spindle-side air flow path 94, which serve as the second reverse air supply path, are formed across the spindle 32 and each of the mounts 50, 581, 582.

[0094] 6, the annular mount 582 is moved back and forth by the air cylinder 78, but it is also possible to use a configuration in which the disc mount 581 is moved back and forth. In this configuration, the first grinding wheel 591 attached to the disc mount 581 moves in the Z-axis direction, and the first grinding stone 583 moves back and forth relative to the second grinding stone 584.

[0095] 6 may also be provided with a first attachment / detachment mechanism for attaching / detaching the first grinding wheel 591 to / from the disc mount 581, and a second attachment / detachment mechanism for attaching / detaching the second grinding wheel 592 to / from the annular mount 582. Since each attachment / detachment mechanism can be configured in the same way, the configuration of the second attachment / detachment mechanism will be described below with reference to FIGS.

[0096] Fig. 9 is an explanatory plan view of the second attachment / detachment mechanism 5820. As shown in Fig. 9, the second attachment / detachment mechanism 5820 includes a plurality of air cylinders 5821 arranged on the annular mount 582. The plurality of air cylinders 5821 are provided at equal angular intervals (for example, 120°) around the circumference of the annular mount 582.

[0097] Fig. 10 is an explanatory exploded cross-sectional view of the second attachment / detachment mechanism, and is a cross-sectional view taken along line AA in Fig. 9. As shown in Fig. 10, air cylinder 5821 includes accommodation chamber 5822 extending in the circumferential direction of annular mount 582, and piston 5823 that is accommodated in accommodation chamber 5822 and is movable in the extension direction (horizontal direction) of accommodation chamber 5822. Fixed claw 5825 is connected to piston 5823 of air cylinder 5821 via connecting portion 5824, and fixed claw 5825 is moved in the circumferential direction (horizontal direction) of annular mount 582 by the forward and backward movement of piston 5823. A claw movement groove 5826 is formed in annular mount 582 so that connecting portion 5824 can move horizontally when air cylinder 5821 is driven.

[0098] The second attachment / detachment mechanism 5820 further includes a claw accommodating portion 5922 formed in a wheel base 5921 of the second grinding wheel 592. The claw accommodating portion 5922 is formed in a groove shape with an entrance on the upper surface of the wheel base 5921, and has a recess 5923 formed in part of the bottom side that fits with the fixed claw 5825. After the fixed claw 5825 is accommodated in the claw accommodating portion 5922, the fixed claw 5825 is moved circumferentially around the wheel base 5921 and fitted into the recess 5923, thereby maintaining the second grinding wheel 592 attached to the annular mount 582.

[0099] An advancing air supply passage 95 and a retreating air supply passage 96 are connected to the accommodation chamber 5822 by the air cylinder 5821. More specifically, the advancing air supply passage 95 communicates with one end of the accommodation chamber 5822 (the end opposite the connecting portion 5824 across the piston 5823). The retreating air supply passage 96 communicates with the other end of the accommodation chamber 5822 (the end where the connecting portion 5824 of the piston 5823 is located). Air is supplied to the advancing air supply passage 95 in the same way as to the first spindle-side air flow passage 91 described above, and air is supplied to the retreating air supply passage 96 in the same way as to the second spindle-side air flow passage 92 described above.

[0100] Therefore, the piston 5823 and the fixed claw 5825 move forward and backward by switching between the supply of air from the forward air supply passage 95 and the backward air supply passage 96. This forward and backward movement of the fixed claw 5825 switches between fitting and disengaging the fixed claw 5825 with respect to the recess 5923, and the attachment state of the second grinding wheel 592 to the annular mount 582 is maintained or released. [Industrial Applicability]

[0101] As described above, the present invention has the effect of being able to clean and remove grinding debris even if the grinding debris is interposed between the upper surface of the sensor unit and the lower surface of the grinding wheel during setup. [Explanation of symbols]

[0102] 31: Spindle unit 32: Spindle 34: Casing 50: Wheel mount (mount) 53: Grinding wheel (processing tool) 581: Disk mount (first mount, mount) 582: Annular mount (second mount, mount) 593: First grinding wheel (first processing tool) 594: Second grinding wheel (second processing tool) 70: Air cylinder 72: Piston 73:Connection part 74:Fixed claw 78: Air cylinder 782: Annular Piston (Piston) 783: Shaft 81: First casing side air flow path (first forward air supply path) 82: Second casing side air flow path (first reverse air supply path) 83: Third casing side air flow path (first forward air supply path) 84: 4th casing side air passage (1st reverse air supply passage) 91: First spindle side air flow path (second forward air supply path) 92: Second spindle side air passage (second reverse air supply passage) 93: Third spindle side air passage (second forward air supply passage) 94: 4th spindle side air passage (2nd reverse air supply passage) BJ: Retract joint FJ: Progressive joint RB: Radial air bearing (air bearing) TB: Thrust air bearing (air bearing) W: Wafer (workpiece)

Claims

1. A spindle unit comprising: a mount for mounting a processing tool for processing a workpiece; a spindle having the mount connected to a tip thereof; and a casing for rotatably supporting the spindle by an air bearing, an air cylinder disposed on the spindle or the mount, the piston of which moves back and forth when air is supplied; a first advancing air supply passage disposed in the casing for advancing the piston; a second advancing air supply passage disposed at least in the spindle for advancing the piston; and an advancing joint disposed in the casing at a portion where the air bearing is formed and in the spindle for joining the first advancing air supply passage and the second advancing air supply passage; a first reverse air supply passage disposed in the casing for retracting the piston; a second reverse air supply passage disposed in at least the spindle for retracting the piston; and a reverse joint disposed in the casing at a portion where the air bearing is formed and in the spindle, for joining the first reverse air supply passage and the second reverse air supply passage.

2. 2. The spindle unit according to claim 1, further comprising: a fixed claw for fixing the processing tool; and a connecting portion for connecting the fixed claw to the air cylinder and for moving the fixed claw in the horizontal direction.

3. The processing tool includes a first processing tool and a second processing tool, The mount includes a first mount for mounting the first processing tool, and a second mount disposed outside the first mount for mounting the second processing tool, 2. The spindle unit according to claim 1, further comprising a shaft that connects either the first mount or the second mount to the air cylinder and moves the first processing tool and the second processing tool back and forth relative to each other.

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