JP2010201603A - Grinding wheel - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a grinding wheel sufficiently transmitting ultrasonic vibration to a grinding stone. <P>SOLUTION: The grinding wheel is equipped with: a mount installing plate 68 installed on a wheel mount 20; a wheel base, which includes a columnar connecting part 48 having a first thickness for being connected to the mount installing plate, an annular resonance part 49 having a second thickness thinner than the first thickness, an annular vibration transmitting part 53 having a third thickness thinner than the second thickness, and a circular grinding stone fixed part 57 on which the grinding stones are circularly fixed; a plurality of the grinding stones 60 fixed on the circular grinding stone fixed part of the wheel base; an ultrasonic vibrator 56 arranged on the annular resonance part 49 of the wheel base; and a cylindrical thin plate 76 fastened on an outer periphery of the mount installing plate and an outer periphery of the wheel base so as to surround an overall circumference of the mount installing plate and an overall circumference of the wheel base. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to a grinding wheel mounted on a grinding apparatus for grinding a workpiece such as a semiconductor wafer.

  A semiconductor wafer in which a number of devices such as IC and LSI are formed on the surface, and each device is partitioned by a line to be divided (street), the back surface is ground by a grinding machine and processed to a predetermined thickness. A dividing line is cut by a cutting device (dicing device) to be divided into individual devices, and the divided devices are used for electric devices such as mobile phones and personal computers.

  A grinding apparatus for grinding a back surface of a wafer includes a chuck table for holding a wafer, and a grinding means on which a grinding wheel having a grinding wheel for grinding the wafer held on the chuck table is rotatably mounted. The wafer can be ground to a desired thickness with high accuracy.

  By the way, when brittle hard materials such as sapphire, silicon nitride, lithium tantalate, and artic are ground with a grinding apparatus, it takes a long time and there is a problem that productivity is poor. Has been developed and a patent application has been filed (Japanese Patent Laid-Open No. 2008-23693).

JP 2008-23893 A

  However, it has been found that the structure of the grinding wheel disclosed in Patent Document 1 has a problem that the ultrasonic vibration generated by the ultrasonic vibrator is not sufficiently transmitted to the grinding wheel.

  The present invention has been made in view of these points, and an object of the present invention is to provide a grinding wheel that can sufficiently transmit ultrasonic vibration generated by an ultrasonic vibrator to a grinding wheel.

  According to the present invention, a grinding wheel is mounted on a wheel mount fixed to the tip of a spindle of a grinding apparatus, the mount mounting plate mounted on the wheel mount, and formed at the center and coupled to the mount mounting plate. A cylindrical connecting portion having a first thickness; an annular resonant portion formed surrounding the cylindrical connecting portion and having a second thickness smaller than the first thickness; and surrounding the annular resonant portion A wheel base having an annular vibration transmission portion formed and having a third thickness smaller than the second thickness, and an annular grinding wheel fixing portion surrounding the annular vibration transmission portion and fixing the grinding wheel in an annular shape; A plurality of grinding wheels fixed to the annular grinding wheel fixing portion of the wheel base, an ultrasonic vibrator disposed in the annular resonance portion of the wheel base, and an entire circumference of the mount mounting plate; Grinding wheels, characterized by comprising a cylindrical sheet which is fastened to the outer periphery of the outer and the wheel base of the mounting attachment plates are provided so as to surround the entire circumference of the wheel base.

  Since the grinding wheel of the present invention has a thin annular vibration transmission portion formed so as to surround the annular resonance portion to which the ultrasonic transducer is attached, the ultrasonic wave generated by the ultrasonic transducer is generated. Vibration can be sufficiently transmitted to the grinding wheel, and the cylindrical thin plate fastened to the outer periphery of the mount mounting plate and wheel base can suppress the deflection of the wheel base against vertical load, so grinding brittle hard materials such as sapphire efficiently. Can do.

It is an external appearance perspective view of the grinding device with which the grinding wheel of the present invention was equipped. It is a partial cross section front view of the grinding unit of this invention embodiment. It is a disassembled perspective view of the grinding wheel of this invention embodiment. It is a disassembled perspective view of the grinding wheel with which a wheel mount and a wheel mount are mounted | worn. It is a longitudinal cross-sectional view of a grinding wheel.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 shows an external perspective view of a grinding apparatus 2 equipped with a grinding wheel according to an embodiment of the present invention. Reference numeral 4 denotes a housing of the grinding apparatus 2, and a column 6 is erected on the rear side of the housing 4. A pair of guide rails 8 extending in the vertical direction is fixed to the column 6.

  A grinding unit (grinding means) 10 is mounted along the pair of guide rails 8 so as to be movable in the vertical direction. The grinding unit 10 includes a spindle housing 12 and a support portion 14 that holds the spindle housing 12, and the support portion 14 is attached to a moving base 16 that moves up and down along a pair of guide rails 8. Yes.

  The grinding unit 10 includes a spindle 18 rotatably accommodated in a spindle housing 12, a wheel mount 20 fixed to the tip of the spindle 18, and a plurality of grinding wheels that are screwed to the wheel mount 20 and arranged annularly. A grinding wheel 22 having an electric motor for rotating the spindle 18 is included.

  The grinding apparatus 2 includes a grinding unit moving mechanism 32 including a ball screw 28 that moves the grinding unit 10 in the vertical direction along the pair of guide rails 8 and a pulse motor 30. When the pulse motor 30 is driven, the ball screw 28 rotates and the moving base 16 is moved in the vertical direction.

  A recess 4a is formed on the upper surface of the housing 4, and a chuck table mechanism 34 is disposed in the recess 4a. The chuck table mechanism 34 includes a chuck table 36 and is moved in the Y-axis direction between a wafer attachment / detachment position A and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown). 38 and 40 are bellows. On the front side of the housing 4, an operation panel 42 on which an operator of the grinding device 2 inputs search conditions and the like is disposed.

  As shown in FIGS. 2 and 4, the tip of the spindle 18 is formed in a small diameter tip 18a, and a wheel mount 20 is fixed to the small diameter tip 18a. The wheel mount 20 has four round holes 90. By inserting bolts 88 into these round holes 90 and screwing the bolts 88 into the screw holes of the grinding wheel 22, the grinding wheel 22 is mounted on the wheel mount. 20 is attached.

  The spindle 18 is formed with a through hole 21 penetrating the spindle 18 in the vertical direction, and the tip of the through hole 21 is formed in a connector insertion hole 19 having an enlarged diameter as shown in FIG. . A concave connector 92 is inserted into the connector insertion hole 19, and a convex connector 64 connected to an ultrasonic transducer described later is fitted into the concave connector 92.

  Referring to FIG. 3, an exploded perspective view of the grinding wheel 22 of the embodiment of the present invention is shown. 4 is an exploded perspective view of the wheel mount 20 and the grinding wheel 22, and FIG. 5 is a longitudinal sectional view of the grinding wheel 22.

  A wheel base 46 of the grinding wheel 22 is integrally formed with a columnar connecting portion 48 connected to the mount mounting plate 68 at the center of the upper surface 46 a of the wheel base 46. The columnar connecting portion 48 has a first thickness. When the diameter of the wheel base 46 is 200 mm, the first thickness is, for example, 20 mm.

  The wheel base 46 has an annular resonance part 49 having a second thickness smaller than the first thickness formed so as to surround the columnar connection part 48. The second thickness is, for example, 15 mm.

  As is apparent from the cross-sectional view of FIG. 5, an annular groove 55 is formed on the upper surface of the annular resonance portion 49, and an annular ultrasonic transducer 56 is inserted into the annular groove 55 and fixed by an adhesive or the like. Has been. As the ultrasonic transducer 56, a plurality of arc-shaped ultrasonic transducers may be inserted and fixed in the annular groove 55.

  Here, without forming the annular groove 55 on the upper surface of the annular resonance portion 49, the annular or arcuate ultrasonic transducer 56 is directly bonded to the upper surface of the annular resonance portion 49 with an adhesive having a strong adhesive force. Also good.

  The wheel base 46 is further formed with an annular groove 51 so as to surround the annular resonance portion 49, and the annular groove 51 has an annular shape having a third thickness that is thinner than the annular resonance portion 49 having the second thickness. A vibration transmission unit 53 is defined. The third thickness is 3 mm, for example.

  The wheel base 46 has an annular grinding wheel fixing portion 57 having a second thickness on the outer periphery of the annular vibration transmitting portion 53, and the lower surface of the annular grinding wheel fixing portion 57, that is, the lower surface 46 b of the wheel base 46. A plurality of grinding wheels 60 are fixed to the outer periphery in a ring shape.

  The cylindrical connecting portion 48 is formed with four vertical round holes 50, two horizontal holes 52, and a center hole 54, and a conductive wire 62 having one end connected to the convex connector 64 has a center. The other end is connected to the ultrasonic transducer 56 through the hole 54 and the horizontal hole 52. A plurality of screw holes 58 are formed at predetermined intervals on the outer periphery of the wheel base 46.

  Reference numeral 68 denotes a disc-shaped mount mounting plate, and the mount mounting plate 68 is screwed with a center hole 70 corresponding to the center hole 54 of the cylindrical connecting portion 48 and a bolt 88 for fastening the grinding wheel 22 to the wheel mount 20. Four screw holes 72 are formed.

  A plurality of screw holes 74 are formed on the outer periphery of the mount mounting plate 68 at a predetermined interval. Further, four screw holes are formed on the lower surface of the mount mounting plate 68 at positions corresponding to the round holes 50 of the wheel base 46.

  A thin cylindrical plate 76 has a plurality of round holes 78 corresponding to the screw holes 58 of the wheel base 46 and a plurality of round holes 80 corresponding to the screw holes 74 of the mount mounting plate 68. The cylindrical thin plate 76 is formed from a stainless steel plate having a thickness of 0.3 mm, for example.

  To assemble the grinding wheel 22, as shown in FIG. 5, the bolt 82 is screwed into the screw hole of the mount mounting plate 68 through the round hole 50 of the cylindrical connecting portion 48 of the wheel base 46, and the wheel base 46 is mounted. Secure to the plate 68. A counterbore 66 that accommodates the head of the bolt 82 is formed on the lower surface 46 b of the wheel base 46.

  Next, the screw 84 is fastened to the screw hole 58 of the wheel base 46 through the circular hole 78 of the cylindrical thin plate 76 so that the cylindrical thin plate 76 surrounds the entire circumference of the wheel base 46 and the mount mounting plate 68. The screw 86 is fastened to the screw hole 74 of the mount mounting plate 68 through the round hole 80 of the cylindrical thin plate 76.

  Thereby, the grinding wheel 22 as shown in FIG. 4 is assembled. The grinding wheel 22 is attached to the wheel mount 20 by screwing the bolts 88 through the round holes 90 of the wheel mount 20 into the screw holes 72 of the mount mounting plate 68.

As the ultrasonic transducer 56, barium titanate (BaTiO ₃ ), lead zirconate titanate (Pb (Zi, Ti) O ₃ ), lithium niobate (LiNbO ₃ ), or lithium tantalate (LiTaO ₃ ) is used. Can do.

  Referring back to FIG. 2, the grinding unit 10 includes an electric motor 94 that rotates the spindle 18. The electric motor 94 is composed of, for example, a permanent magnet motor. The electric motor 94 includes a rotor 98 made of a permanent magnet mounted on a motor mounting portion 96 formed at an intermediate portion of the spindle 18, and a stator coil 100 disposed on the spindle housing 12 on the outer peripheral side of the rotor 98. Is done.

  In the electric motor 94 configured as described above, the rotor 98 is rotated by applying AC power to the stator coil 100 by a power supply unit described later, and the spindle 18 to which the rotor 98 is mounted is rotated.

  The grinding unit 10 further includes power supply means 102 that applies AC power to the ultrasonic transducer 56 and applies AC power to the electric motor 94. The power supply means 102 includes a rotary transformer 104 disposed at the upper end of the spindle 18.

  The rotary transformer 104 includes a power receiving unit 106 disposed at the upper end of the spindle 18 and a power feeding unit 108 disposed to face the power receiving unit 106. The power receiving means 106 includes a rotor core 110 attached to the spindle 18 and a power receiving coil 112 wound around the rotor core 110.

  A conductive wire 93 is connected to the power receiving coil 112 of the power receiving means 106 configured as described above. The conductive wire 93 is disposed in a through hole 21 formed in the axial direction at the center of the spindle 18, and the tip thereof is connected to a concave connector 92 shown in FIG.

  The power feeding means 108 includes a stator core 114 disposed on the outer peripheral side of the power receiving means 106 and a power feeding coil 116 disposed on the stator core 114. AC power is supplied to the power supply coil 116 of the power supply unit 108 configured as described above via the electrical wiring 118.

  The power supply means 102 is an AC power supply 120, a voltage adjusting means 122 inserted between the AC power supply 120 and the power supply coil 116 of the rotary transformer 104, and a frequency adjustment for adjusting the frequency of the AC power supplied to the power supply means 108. Means 124, a control means 126 for controlling the voltage adjustment means 122 and the frequency adjustment means 124, and an input means 128 for inputting the amplitude and the like of the ultrasonic vibration applied to the grinding wheel to the control means 126 are provided.

  The AC power supply 120 supplies AC power to the stator coil 100 of the electric motor 94 via the control circuit 132 and the electric wiring 130. As the frequency adjusting means 124, a digital function generator provided by NF Circuit Design Block Co., Ltd., a trade name “DF-1905” can be used. According to DF-1905, the frequency can be appropriately adjusted within a range of 10 kHz to 500 kHz.

  The grinding operation of the grinding device 2 configured as described above will be described below. On the chuck table 36 positioned at the wafer attaching / detaching position A shown in FIG. Next, the chuck table 36 is moved in the Y-axis direction and positioned at the grinding position B.

  While rotating the chuck table 36 at, for example, 300 rpm with respect to the wafer thus positioned, the grinding wheel 22 is rotated in the same direction as the chuck table 36 at, for example, 6000 rpm, and the grinding unit moving mechanism 32 is operated. The grinding wheel 60 is brought into contact with the back surface of the wafer.

  During this grinding process, AC power having a predetermined frequency is supplied to the power supply coil 116 of the power supply means 108 constituting the rotary transformer 104 by the power supply means 102. As a result, AC power of a predetermined frequency is applied to the ultrasonic transducer 56 through the power receiving coil 112, the conductive wire 93, the concave connector 92, the convex connector 64, and the conductive wire 62 of the rotating power receiving means 106, and the ultrasonic vibration. The child 56 ultrasonically vibrates mainly in the radial direction (radial direction).

  This ultrasonic vibration is transmitted to the plurality of grinding wheels 60 through the thin annular vibration transmitting portion 53 formed so as to surround the annular resonance portion 49, and the grinding wheel 60 is ultrasonically vibrated in the radial direction. .

  In the grinding wheel 22 of the present embodiment, the cylindrical thin plate 76 fastened to the outer periphery of the wheel base 46 and the outer periphery of the mount mounting plate 68 so as to surround the entire periphery of the wheel base 46 and the disc-shaped mount mounting plate 68. Since the bending of the wheel base 46 during grinding can be suppressed and the thin vibration transmitting portion 53 is formed so as to surround the annular resonance portion 49 to which the ultrasonic transducer 56 is attached, the ultrasonic vibration The ultrasonic vibration generated from the child 56 is efficiently transmitted to the plurality of grinding wheels 60 via the annular vibration transmitting portion 53.

  In this way, while the grinding wheel 60 is vibrated mainly in the radial direction by the ultrasonic vibrator 56, the grinding wheel 22 is ground and fed by a predetermined amount at a predetermined grinding feed speed (for example, 3 to 5 μm / second). Perform grinding.

  When the grinding wheel 60 is ultrasonically vibrated in the radial direction, the grinding debris generated by grinding and staying between the abrasive grains of the grinding wheel 60 and causing clogging flows together with the grinding water by the fine vibration acting on the grinding wheel 60. To be removed.

  Therefore, clogging of the grinding wheel 60 can be prevented, and even a brittle hard material such as sapphire, silicon nitride, lithium tantalate, or altic can be efficiently ground by ultrasonic vibration energy.

The grinding wheel 22 according to the embodiment of the present invention in which the ultrasonic vibrator 56 is formed from lead zirconate titanate (Pb (Zi, Ti) O ₃ ) is attached to the wheel mount 20, and the ultrasonic vibrator 56 has a frequency of 19 kHz. A voltage of 75V was applied.

  As a result, the grinding wheel 60 vibrated with an amplitude of around 6.5 μm in the radial direction (radial direction) at a frequency of 19 kHz. Although the grinding wheel 60 also vibrates ultrasonically in the axial direction, the amplitude in the axial direction was around 2.0 μm and was smaller than that in the radial direction.

  For comparison, when the grinding wheel disclosed in Patent Document 1 was mounted on a wheel mount and an AC voltage was applied to the ultrasonic vibrator under the same conditions as in the example, the grinding wheel was slightly ultrasonic in the radial direction. Although it vibrated, its amplitude was around 0.2 μm, and sufficient amplitude was not obtained.

2 Grinding device 10 Grinding unit 20 Wheel mount 22 Grinding wheel 36 Chuck table 46 Wheel base 48 Cylindrical connecting part 49 Annular resonance part 53 Annular vibration transmission part 56 Ultrasonic vibrator 60 Grinding wheel 68 Disc-shaped mount mounting plate 76 Cylindrical thin plate

Claims (1)

A grinding wheel mounted on a wheel mount fixed to a spindle tip of a grinding device,
A mount mounting plate to be mounted on the wheel mount;
A cylindrical connecting portion formed at the center and having a first thickness connected to the mount mounting plate, and an annular shape surrounding the cylindrical connecting portion and having a second thickness smaller than the first thickness A resonating portion, an annular vibration transmitting portion formed surrounding the annular resonating portion and having a third thickness smaller than the second thickness, and the grinding wheel surrounding the annular vibration transmitting portion are fixed in an annular shape. A wheel base having an annular grinding wheel fixing part;
A plurality of grinding wheels fixed to the annular grinding wheel fixing portion of the wheel base;
An ultrasonic transducer disposed in the annular resonant portion of the wheel base;
A cylindrical thin plate fastened to the outer periphery of the mount mounting plate and the outer periphery of the wheel base so as to surround the entire periphery of the mount mounting plate and the entire periphery of the wheel base;
A grinding wheel characterized by comprising:

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