JP5096120B2 - Ultrasonic wheel - Google Patents

Description

  The present invention relates to an ultrasonic wheel such as a grinding wheel or a cup wheel.

  In the semiconductor device manufacturing process, a plurality of regions are defined by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and ICs, LSIs, etc. are defined in these partitioned regions. Form a device. Then, the semiconductor wafer is cut along a street with a cutting blade in which abrasive grains are hardened with bonds to divide the region where the device is formed to manufacture individual semiconductor chips. In addition, optical device wafers in which gallium nitride compound semiconductors are stacked on the surface of sapphire substrates are also cut along the streets to divide into individual optical devices such as light-emitting diodes and laser diodes, which are widely used in electronic equipment. Is done.

  The wafer divided in this way is ground to a predetermined thickness by a grinding device before being cut along the street. However, when the back surface of the wafer is ground with the grinding wheel of the grinding device, the grinding wheel is clogged, and the grinding ability is lowered. In particular, when grinding or processing a brittle hard material such as sapphire, silicon nitride, lithium tantalate, or Altic, or a composite material such as a wafer with a Cu electrode, or a metal, it is produced due to clogging of the grinding wheel or a decrease in grinding ability due to heat generation. There is a problem that the performance is significantly reduced.

  In order to solve such a problem, at least one of a chuck table that holds a workpiece and a grindstone holding member that holds a grinding wheel that grinds the workpiece held on the chuck table is provided with a grinding wheel. There has been proposed a grinding apparatus in which ultrasonic application means for applying ultrasonic vibration is provided to a grinding portion of a workpiece (see, for example, Patent Document 1).

JP-A-2-232164

  However, in the structure disclosed in Patent Document 1, particularly in a grinding wheel or cup wheel formed of a relatively heavy bond such as a metal bond, the ultrasonic vibration by the ultrasonic vibrator is attenuated by the influence of the bond. There is a problem that difficult-to-cut materials cannot be ground and processed smoothly, such as unnecessary vibration.

  The present invention has been made in view of the above, and provides an ultrasonic wheel capable of obtaining a sufficient amplitude by transmitting ultrasonic vibration generated by an ultrasonic vibrator to a grindstone in a desired direction. The purpose is to do.

  In order to solve the above-described problems and achieve the object, an ultrasonic wheel according to the present invention includes a wheel mount provided at one end of a rotary spindle constituting a processing means for processing a workpiece held on a chuck table. An ultrasonic wheel that includes a wheel base attached to the wheel base and an annular grindstone attached to the wheel base, and generates ultrasonic vibration during processing. The wheel base is connected to the wheel mount. The grindstone is composed of an annular connecting portion and an annular grindstone mounting portion connected to the wheel mount via the connecting portion, and the grindstone mounting portion is mounted on the surface opposite to the connecting portion. And an ultrasonic transducer that generates ultrasonic vibrations, and the whetstone mounting portion is divided into the whetstone side and the connecting portion side with a reference line assumed at the center in the thickness direction as a boundary. When the is characterized by having a weight adjustment member to equalize the displacement vector by ultrasonic vibration of the connecting portion side to the grinding wheel side to the connecting portion.

  The ultrasonic wheel according to the present invention is characterized in that, in the above invention, the weight adjusting member is disposed at a position near the outer periphery of the grindstone mounting portion.

  In the ultrasonic wheel according to the present invention, the grindstone mounting portion is divided into the grindstone side and the connecting portion side when the grindstone mounting portion is divided into the grindstone side and the connecting portion side on the basis of the reference line assumed at the center in the thickness direction. Since there is a weight adjustment member on the connecting portion side that equalizes the displacement vector due to the ultrasonic vibration, a displacement vector component generated on the grindstone side when ultrasonic vibration is transmitted is generated on the connecting portion side having the weight adjusting member. By canceling with the displacement vector, generation of unnecessary vibration can be eliminated and ultrasonic vibration can be transmitted to the grindstone in a desired direction, so that the grindstone can be vibrated with sufficient amplitude. There is an effect that can be.

  Hereinafter, an ultrasonic wheel which is the best mode for carrying out the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing a configuration example of the entire processing apparatus including the ultrasonic wheel of the present embodiment, and FIG. 2 is a longitudinal side view of a spindle unit included in the processing apparatus that also shows an electrical equipment control system. is there. The processing apparatus according to the present embodiment is a grinding apparatus and includes an apparatus housing 2. The apparatus housing 2 has a rectangular parallelepiped main portion 21 extending elongated and a pair of upright walls 22 provided at a rear end portion (upper right end in FIG. 1) of the main portion 21 and extending substantially vertically. A pair of guide rails 221 extending in the vertical direction are provided on the front surface of the upright wall 22. The processing means 3 is mounted on the pair of guide rails 221 so as to be movable in the vertical direction.

  The processing means 3 includes a moving base 31 and a spindle unit 4 mounted on the moving base 31. The movable base 31 is provided with a pair of leg portions 311 extending in the vertical direction on both sides of the rear surface, and a guide groove 312 that slidably engages with the pair of guide rails 221 is formed on the pair of leg portions 311. Yes. A support portion 313 protruding forward is provided on the front surface of the moving base 31, and the spindle unit 4 is attached to the support portion 313.

  The spindle unit 4 includes a spindle housing 41 mounted on the support portion 313 and a rotating spindle 42 that is rotatably disposed on the spindle housing 41. Here, as shown in FIG. 2, the spindle housing 41 is formed in a substantially cylindrical shape and includes a shaft hole 411 penetrating in the axial direction. A rotating spindle 42 that is inserted through a shaft hole 411 formed in the spindle housing 41 is provided with a thrust bearing flange 421 that is formed to protrude in the radial direction at the center thereof. Thereby, the rotary spindle 42 is rotatably supported by high-pressure air supplied between the inner wall of the shaft hole 411. One end of the rotary spindle 42 (the lower end in FIG. 2) is disposed so as to protrude from the lower end of the spindle housing 41, and a wheel mount 43 is provided at one end thereof. The ultrasonic wheel 5 according to the present embodiment is attached to the lower surface of the wheel mount 43. The ultrasonic wheel 5 will be described later.

  Further, the machining apparatus includes a machining unit feed mechanism 10 that moves the spindle unit 4 in the vertical direction along the pair of guide rails 221. The processing unit feed mechanism 10 includes a male screw rod 101 that is disposed on the front side of the upright wall 22 and extends substantially vertically. The male screw rod 101 is rotatably supported by bearing members 102 and 103 whose upper end and lower end are attached to the upright wall 22. The upper bearing member 102 is provided with a pulse motor 104 that rotationally drives the male screw rod 101. A through female screw hole (not shown) extending rearward from the center in the width direction is formed on the rear surface of the movable base 31, and the male screw rod 101 is screwed into the through female screw hole. Accordingly, when the pulse motor 104 rotates in the forward direction, the moving base 31, that is, the processing means 3 moves down (forwards), and when the pulse motor 104 rotates in the reverse direction, the moving base 31, that is, the processing means 3 moves up (retracts).

  The chuck table mechanism 11 is disposed in the main portion 21 of the housing 2. The chuck table mechanism 11 includes a chuck table 12, a cover member 13 that covers the periphery of the chuck table 12, and bellows means 14 and 15 disposed before and after the cover member 13. The chuck table 12 is rotated by a rotating means (not shown), and is configured to suck and hold the workpiece W on its upper surface by operating a suction means (not shown). Further, the chuck table 12 is moved between a workpiece placement area 24 shown in FIG. 1 and a grinding area 25 facing the ultrasonic wheel 5 constituting the spindle unit 4 by a chuck table moving means (not shown). Is done. The bellows means 14 and 15 are made of an appropriate material such as a campus cloth. The front end of the bellows means 14 is fixed to the front wall of the main portion 21, and the rear end is fixed to the front end surface of the cover member 13. The front end of the bellows means 15 is fixed to the rear end surface of the cover member 13, and the rear end is fixed to the front surface of the upright wall 22 of the apparatus housing 2. When the chuck table 12 moves in the direction indicated by the arrow 23a, the bellows means 14 expands and the bellows means 15 contracts. Conversely, when the chuck table 12 moves in the direction indicated by the arrow 23b, the bellows means 14 moves. The bellows means 15 contracts and expands.

  Next, the ultrasonic wheel 5 of the present embodiment will be described with reference to FIGS. FIG. 3 is an exploded perspective view showing an ultrasonic wheel, FIG. 4 is a partial cross-sectional view of a connecting portion, and FIG. 5 is a longitudinal front view showing a wheel base portion. The ultrasonic wheel 5 according to the present embodiment includes a wheel base 51 attached to the wheel mount 43 and a plurality of grindstones 52 mounted on the lower surface of the wheel base 51 so as to form an annular shape. The wheel base 51 is formed in a size corresponding to the wheel mount 43 and has an annular connecting portion 511 for connecting to the wheel mount 43, and an annular grindstone connected to the wheel mount 43 via the connecting portion 511. And a mounting portion 512.

  The upper side of the connecting portion 511 is fixed to the wheel mount 43 and becomes the restraint side, and a plurality of screw holes 511a corresponding to a plurality of bolt insertion holes (not shown) formed in the wheel mount 43 are formed. . Further, as shown in the cross-sectional view of FIG. 4, a plurality of slit-like annular grooves 511b are alternately bitingly formed on the outer peripheral surface and the inner peripheral surface on the lower side of the connecting portion 511 to which the grindstone mounting portion 512 is fixed. Thus, an elastic coupling structure that has elasticity in the radial direction and the thickness direction so as not to hinder vibration of the grindstone mounting portion 512 by an ultrasonic vibrator, which will be described later, and insulates vibrations from the upper restraint portion side It is configured as.

  The grindstone mounting portion 512 has an opening 512a formed at the center and is formed in an annular shape as a whole, but the size of the opening 512a may be any size as long as it can be inserted with wiring, and is small. May be. At a position near the outer periphery on the lower surface side (the side opposite to the connecting portion 511) of the grindstone mounting portion 512, a plurality of grindstones 52 are mounted in an appropriate manner in the circumferential direction by an adhesive. ing. One grinding wheel formed in an annular shape may be used.

  Further, in the grindstone mounting portion 512, for example, positions on the inner circumferential side with respect to the grindstone 52, and upper and lower double-sided positions that are concentric with the grindstone 52 arranged in an annular shape around the center of the ultrasonic wheel 5 are appropriately set. A plurality of ultrasonic transducers 6 attached with an adhesive are arranged in an annular shape. One ultrasonic transducer formed in an annular shape may be used. These ultrasonic vibrators 6 are for applying ultrasonic vibrations to the grindstone 52 through the grindstone mounting portion 512, and for example, piezoelectric such as barium titanate, lead zirconate titanate (PZT), lithium tantalate, etc. It is made of ceramics. As the ultrasonic transducer 6 of the present embodiment, for example, a PZT transducer is used. The target vibration direction of the ultrasonic transducer 6 is set to be the radial direction of the grindstone mounting portion 512. In this way, one end of the conductive wire 61 is connected to the + and − terminals on the front and back surfaces of the ultrasonic transducer 6 mounted on the upper and lower surfaces of the grindstone mounting portion 512. The conductive wire 61 is connected to the + and − terminals of the ultrasonic transducer 6 on the lower surface side through the opening 512a. The other end of the conductive wire 61 is connected to a convex connector (not shown). This convex connector is detachably connected to a power supply means described later.

Further, an annular weight adjusting member 513 is fixed on the connecting portion 511 side of the grindstone mounting portion 512, for example, at a position near the outer periphery corresponding to the position of the grindstone 52. Thereby, the grindstone mounting portion 512 is connected to the connecting portion 511 via the weight adjusting member 513. Here, as shown in FIG. 5, the weight adjusting member 513 includes the grindstone mounting portion 512, the grindstone side portion A, the connecting portion side portion B, and the reference line L assumed at the center in the thickness direction of the grindstone mounting portion 512. In order to equalize the displacement vectors δ ₁ and δ ₂ due to ultrasonic vibration of the grinding wheel side portion A and the connecting portion side portion B.

Here, the conditions that the weight adjusting member 513 should satisfy will be described. First, the volume, density, weight, and elastic modulus of the grinding wheel side portion A (including the grinding wheel 52) with respect to the reference line L are V ₁ , ρ ₁ , m ₁ , E ₁ , respectively, and the amplitude attenuation rate is ξ ₁ , When the angular velocity at resonance is ω ₁ and the vibration application force is F ₁ , the displacement vector δ ₁ follows the equation of motion:
δ ₁ = F ₁ / (V ₁ · ρ ₁ · m ₁ ² +2 · m ₁ · ξ ₁ · ω ₁ + E ₁ )
Indicated by Similarly, the volume, density, weight, and elastic modulus of the connecting portion side portion A (including the weight adjusting member 513) with respect to the reference line L are V ₂ , ρ ₂ , m ₂ , and E ₂ , respectively, and the amplitude is attenuated. When the rate is ξ ₂ , the angular velocity at resonance is ω ₂ , and the vibration application force is F ₂ , the displacement vector δ ₂ follows the equation of motion:
δ ₂ = F ₂ / (V ₂ · ρ ₂ · m ₂ ² + 2 · m ₂ · ξ ₂ · ω ₂ + E ₂ )
Indicated by

Therefore, in order to satisfy δ ₁ = δ ₂ , the weight adjusting member 513 is
F ₁ / (V ₁ · ρ ₁ · m ₁ ² +2 · m ₁ · ξ ₁ · ω ₁ + E ₁ )
= F ₂ / (V ₂ · ρ ₂ · m ₂ ² + 2 · m ₂ · ξ ₂ · ω ₂ + E ₂ )
What is necessary is just to be formed with the material which consists of the volume, density, weight, and elasticity modulus which satisfy | fill. In order to satisfy this condition, it is advantageous to provide the weight adjusting member 513 as close to the outer periphery as possible in the grindstone mounting portion 512 as in the present embodiment. You may provide in the appropriate position of the connection part side part B not only in this position.

  The ultrasonic wheel 5 configured as described above is detachably attached to the mount wheel 43 by screwing the fastening bolts 55 respectively inserted through the bolt insertion holes formed in the wheel mount 43 into the screw holes 511a. Is done.

  Returning to FIG. 2 and continuing the description, the spindle unit 4 includes an electric motor 7 for driving the rotary spindle 42 to rotate. The electric motor 7 is, for example, a permanent magnet type motor, and includes a rotor 71 made of a permanent magnet mounted on a motor mounting portion 422 formed at an intermediate portion of the rotary spindle 42, and a spindle housing on the outer peripheral side of the rotor 71. 41 and a stator coil 72 disposed on 41. In the electric motor 7, the rotor 71 rotates when AC power is supplied to the stator coil 72 by power supply means described later, and the rotating spindle 42 on which the rotor 71 is mounted rotates.

  Further, the spindle unit 4 includes power supply means 8 for supplying AC power to the ultrasonic transducer 6 and supplying AC power to the electric motor 7. The power supply means 8 includes a rotary transformer 80 disposed at the rear end of the spindle unit 4. The rotary transformer 80 includes a power receiving unit 81 disposed at the rear end of the rotary spindle 42 and a power feeding unit 82 disposed opposite to the power receiving unit 81 and disposed at the rear end portion of the spindle housing 41. is doing. The power receiving means 81 includes a rotor side core 811 attached to the rotary spindle 42 and a power receiving coil 812 wound around the rotor side core 811. A conductive wire 813 is connected to the power receiving coil 812. The conductive wire 813 is disposed in a hole 423 formed in the axial direction at the center of the rotary spindle 42, and the tip thereof is connected to a concave connector (not shown) that fits with a convex connector (not shown). The power feeding means 82 includes a stator side core 821 disposed on the outer peripheral side of the power receiving means 81 and a power feeding coil 822 disposed on the stator side core 821. AC power is supplied to the power supply coil 822 via the wiring 83.

  The power supply unit 8 includes an AC power supply 91 for AC power supplied to the power supply coil 822 of the rotary transformer 80, a voltage adjustment unit 92, and a frequency adjustment unit 93 for adjusting the frequency of AC power supplied to the power supply unit 82. A control means 94 for controlling the voltage adjustment means 92 and the frequency adjustment means 93; and an input means 95 for inputting the amplitude of the ultrasonic vibration of the ultrasonic vibrator 6 applied to the plurality of grindstones 52 to the control means 94. is doing. The power supply unit 8 supplies AC power to the stator coil 72 of the electric motor 7 via the control circuit 96 and the wiring 721.

  Here, the operation of the spindle unit 4 will be described. When performing a machining operation (grinding operation), AC power is supplied from the power supply means 8 to the stator coil 72 of the electric motor 7. As a result, the electric motor 7 rotates and the rotating spindle 42 rotates, and the ultrasonic wheel 5 attached to the tip of the rotating spindle 42 rotates.

  On the other hand, the power supply means 8 controls the voltage adjusting means 92 and the frequency adjusting means 93 by the control means 94 to control the voltage of the AC power to a predetermined voltage, and converts the frequency of the AC power to a predetermined frequency, thereby rotating the rotary power. The power is supplied to the power supply coil 822 of the power supply means 82 constituting the transformer 80. When AC power having a predetermined frequency and a predetermined voltage is supplied to the feeding coil 822, an annular ultrasonic wave is passed through the power receiving coil 812 of the rotating power receiving means 81, the conductive wire 813, the concave connector, the convex connector, and the conductive wire 61. AC power having a predetermined voltage and a predetermined frequency is applied to the vibrator 6. As a result, the ultrasonic transducer 6 vibrates ultrasonically in the radial direction. The ultrasonic vibration generated by the ultrasonic vibrator 6 is transmitted to the plurality of grindstones 52 via the grindstone mounting portion 512.

  Next, the operation of the processing apparatus of the present embodiment will be described. First, as shown in FIG. 1, a workpiece W to be ground, such as a semiconductor wafer, is placed on the chuck table 12 positioned in the workpiece placement area 24 of the grinding apparatus. When the workpiece W is a semiconductor wafer, a protective tape T is stuck on the surface on which the device is formed, and the protective tape T side is placed on the chuck table 12. The workpiece W placed on the chuck table 12 is sucked and held on the chuck table 12 by suction means (not shown). Then, the chuck table moving means (not shown) is operated to move the chuck table 12 in the direction indicated by the arrow 23 a and to be positioned in the grinding area 25. Then, the outer peripheral edge of the grindstone 52 in the ultrasonic wheel 5 is positioned so as to pass through the rotation center of the chuck table 12 (that is, the center of the workpiece W).

  After being positioned in such a positional relationship, the chuck table 12 is rotated at a rotational speed of, for example, 300 rpm, and the ultrasonic wheel 5 is rotated in the same direction at a rotational speed of, for example, 6000 rpm. That is, by supplying AC power from the power supply means 8 to the stator coil 72, the electric motor 7 rotates and the rotating spindle 42 rotates, and the rotating wheel 5 attached to the tip of the rotating spindle 42 rotates. Then, the ultrasonic wheel 5 is lowered to press the grindstone 52 against the back surface (work surface), which is the top surface of the work W, with a predetermined pressure. As a result, the processing surface of the workpiece W is ground over the entire surface. At this time, the processing liquid is supplied to the processing portion by the plurality of grindstones 52.

  At the time of such processing, AC power having a predetermined voltage and a predetermined frequency is supplied to the power supply coil 822 of the power supply unit 82 constituting the rotary transformer 80 by the power supply unit 8. As a result, AC power having a predetermined voltage and a predetermined frequency is applied to the ultrasonic transducer 6 via the power receiving coil 812, the conductive wire 813, the concave connector, the convex connector, and the conductive wire 61 of the rotating power receiving means 81. As a result, the ultrasonic vibrator 6 is ultrasonically vibrated by being repeatedly displaced in the radial direction. This ultrasonic vibration is transmitted to the plurality of grindstones 52 via the grindstone mounting portion 512, and the plural grindstones 52 vibrate ultrasonically in the radial direction.

At this time, if there is no weight adjusting member 513, the ultrasonic vibration generated by the ultrasonic vibrator 6 is not only the component in the radial direction (horizontal direction) of the grindstone mounting portion 512 that is the desired vibration direction, but also the reference line. Unnecessary vibration due to the downward displacement vector δ ₁ component due to the weight of the grindstone 52 offset to the grindstone side portion A with respect to L also occurs. For this reason, as a whole, a vibration state including unnecessary vibration as indicated by a double arrow by a virtual line is obtained, and depending on the case, the vibration is attenuated. Thereby, even if ultrasonic vibration is applied, the grindstone 52 cannot be vibrated with sufficient amplitude in a desired radial direction, and the difficult-to-cut material cannot be ground smoothly. More ultrasonic wheel 5 is large aperture, the displacement vector [delta] ₁ component by weight of the grindstone 52 is large, it becomes remarkable.

Here, in this embodiment, when the ultrasonic vibration is generated by adding the weight adjusting member 513 to the connecting portion side portion B in the grindstone mounting portion 512, the connecting portion side portion with respect to the reference line L is generated. An upward displacement vector δ ₂ component due to the weight of the weight adjusting member 513 is also generated in B, and this displacement vector δ ₂ is made equal to the displacement vector δ ₁ of the grinding wheel side portion A. As a result, the displacement vector δ ₁ and δ ₂ components generated in the vertical direction cancel each other, and unnecessary vibration is eliminated. Therefore, when the ultrasonic vibrator 6 is driven, ultrasonic vibration is transmitted to the grindstone 52 in a desired radial direction along the reference line L indicated by the solid double arrow in FIG. It can be vibrated with amplitude, and difficult-to-cut materials can be ground smoothly.

  Further, in such a grinding operation, the grindstone mounting portion 512 (weight adjusting member 513) of the ultrasonic wheel 5 and the wheel mount 43 are coupled via a coupling portion 511 having an elastic coupling structure. Since the lower side of the connecting portion 511 formed with the annular groove 511b follows the radial vibration of the portion 512 and elastically displaces in the radial direction, the ultrasonic vibration is not hindered. At the same time, since the upper side of the connecting portion 511 is fixed to the wheel mount 43 so as to be a restraining portion, the ultrasonic vibration is insulated so as not to be transmitted to the wheel mount 43 side.

  The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention. For example, although the ultrasonic wheel of this Embodiment shows the example applied to a grinding wheel, even if it is the case of the cup wheel called not only a grinding wheel but a diamond wheel etc., it is applicable similarly.

It is a perspective view which shows the structural example of the whole grinding apparatus containing the ultrasonic wheel of embodiment of this invention. It is a vertical side view of the spindle unit included in the machining apparatus that also shows the electrical control system. It is a disassembled perspective view which shows an ultrasonic wheel. It is sectional drawing of a part of connection part. It is a vertical front view which shows a wheel base part.

Explanation of symbols

DESCRIPTION OF SYMBOLS 3 Processing means 5 Ultrasonic wheel 6 Ultrasonic vibrator 12 Chuck table 42 Rotating spindle 43 Wheel mount 51 Wheel base 52 Grinding stone 511 Connecting part 512 Grinding stone mounting part 513 Weight adjusting member A Grinding stone side part B Connecting part side part L Reference line W Workpiece

Claims (2)

A wheel base attached to a wheel mount provided at one end of a rotary spindle constituting a processing means for processing a workpiece held on a chuck table, and an annular grindstone mounted on the wheel base. An ultrasonic wheel that generates ultrasonic vibration during processing,
The wheel base is composed of an annular connecting portion connected to the wheel mount, and an annular grindstone mounting portion connected to the wheel mount via the connecting portion,
The grindstone mounting portion includes the grindstone mounted on the side opposite to the connecting portion and an ultrasonic vibrator that generates ultrasonic vibration, and has a reference line assumed at the center in the thickness direction. When the grindstone mounting portion is divided into the grindstone side and the connecting portion side, the connecting portion side has a weight adjusting member for equalizing displacement vectors due to ultrasonic vibrations on the grindstone side and the connecting portion side. An ultrasonic wheel characterized by that.   The ultrasonic wheel according to claim 1, wherein the weight adjusting member is disposed at a position near an outer periphery of the grindstone mounting portion.

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