JP5864882B2 - Cutting equipment - Google Patents

Description

  The present invention relates to a cutting apparatus for cutting a workpiece such as a semiconductor wafer or an optical device wafer while applying ultrasonic vibration to a cutting blade.

  In a semiconductor device manufacturing process, a plurality of regions are partitioned by dividing lines called streets arranged in a lattice pattern on the surface of a substantially wafer-shaped semiconductor wafer, and ICs, LSIs, and the like are divided into the partitioned regions. Form the device. Then, individual semiconductor chips are manufactured by cutting the semiconductor wafer along the streets.

  In addition, an optical device wafer in which a gallium nitride compound semiconductor or the like is laminated on the surface of a sapphire substrate is divided into optical devices such as LED (light emitting diode) and LD (laser diode) by cutting along the street. Such optical devices are widely used in electrical equipment such as digital cameras.

  Cutting along the street of the wafer is usually performed by a cutting device called a dicer. The cutting apparatus includes: a chuck table for holding a workpiece such as a wafer; a cutting means on which a cutting blade for cutting a workpiece held on the chuck table is mounted; and the chuck table and the cutting means are relatively And moving cutting feed means.

  In such a cutting apparatus, the workpiece is cut by rotating the cutting blade at a high speed such as 30000 rpm, cutting the cutting blade into the workpiece, and cutting and feeding the chuck table.

  However, when a hard brittle material such as sapphire, silicon carbide (SiC), glass, or lithium tantalate, which is a substrate of an optical device wafer, is cut with a cutting blade, there is a problem that chips are generated on the cut surface. Also, a wafer with high Mohs hardness such as sapphire is very difficult to cut with a cutting blade.

  In order to solve this problem, an ultrasonic vibrator is arranged on the spindle on which the cutting blade is mounted, and an AC voltage is applied to the ultrasonic vibrator, so that an ultrasonic vibration is applied to the cutting blade while being processed. A cutting apparatus for cutting an object is proposed in, for example, Japanese Patent Application Laid-Open No. 2008-85271.

JP 2008-85271 A

  In a conventional cutting apparatus in which an ultrasonic vibrator is disposed on a spindle, a cutting blade is fastened to a tip surface of the spindle with a screw. Since cutting of a workpiece is performed while supplying cutting water, this type of conventional cutting apparatus has a problem that the cutting water enters between the cutting blade and the tip surface of the spindle, and the tip surface is easily corroded. There is.

  If the fastening force of the screw that attaches the cutting blade to the spindle is not sufficient, this corrosion problem becomes significant. As described above, when unevenness and scratches are caused by corrosion on the tip surface of the spindle, there is a problem that the ultrasonic vibration of the spindle is not sufficiently transmitted to the cutting blade.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a cutting device capable of appropriately transmitting ultrasonic vibrations of the spindle to the cutting blade by preventing scratches and corrosion of the spindle front end surface. Is to provide.

According to the present invention, a chuck table for holding a workpiece, a cutting means having a cutting blade mounted on a tip surface of a spindle that is driven to rotate, and an ultrasonic vibration applying means for applying ultrasonic vibration to the cutting blade. When, a cutting device provided with a moving means for moving the said cutting means and the chuck table, a distal end face of the spindle at least to said cutting blade is mounted, the Vickers hardness is not less than Hv900 A cutting device is provided which is coated with a corrosion-resistant agent composed of an oxide .

Preferably, the oxide is chromium oxide .

  In the cutting apparatus of the present invention, since the anticorrosive agent is coated at least on the front end surface of the spindle, the coating prevents the front end surface of the spindle from being damaged and corroded, and can appropriately transmit ultrasonic vibration to the cutting blade. .

It is a perspective view of the cutting device concerning the embodiment of the present invention. It is a disassembled perspective view of a cutting means (spindle unit). It is a perspective view of a spindle unit. It is a longitudinal cross-sectional view of a spindle unit. It is sectional drawing of the spindle front-end | tip part which concerns on 1st Embodiment. It is sectional drawing of the spindle front-end | tip part which concerns on 2nd Embodiment.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. Referring to FIG. 1, there is shown a perspective view of a cutting apparatus 2 according to an embodiment of the present invention suitable for dicing a hard wafer such as a sapphire wafer and dividing it into individual chips (devices).

  On the front side of the cutting apparatus 2, an operation panel 4 is provided for an operator to input instructions to the apparatus such as machining conditions. In the upper part of the apparatus, there is provided a display means 6 such as a CRT for displaying a guidance screen for an operator and an image taken by an imaging means described later.

  A wafer W such as an optical device wafer is attached to a dicing tape T, which is an adhesive tape having an outer peripheral portion attached to an annular frame F, and is put into the cutting apparatus 2. As a result, the wafer W is supported by the frame F via the dicing tape T, and a plurality of wafers W (for example, 25 sheets) are accommodated in the wafer cassette 8 shown in FIG. The wafer cassette 8 is placed on a cassette elevator 9 that can move up and down.

  Behind the wafer cassette 8, a loading / unloading means 10 for unloading the wafer W before cutting from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8 is disposed. Between the wafer cassette 8 and the loading / unloading means 10, a temporary placement area 12, which is an area on which a wafer to be carried in / out, is temporarily placed, is provided. Positioning means 14 for positioning at a certain position is provided.

  In the vicinity of the temporary placement area 12, transport means 16 having a turning arm that sucks and transports the frame F integrated with the wafer W is disposed, and the wafer W carried to the temporary placement area 12 is It is attracted by the transport means 16 and transported onto the chuck table 18 and is sucked by the chuck table 18, and is held on the chuck table 18 by fixing the frame F by a plurality of fixing means 19.

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction. Above the movement path of the chuck table 18 in the X-axis direction, an alignment unit 20 that detects a street to be cut of the wafer W is provided. It is arranged.

  The alignment unit 20 includes an imaging unit 22 that images the surface of the wafer W, and can detect a street to be cut by a process such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 22 is displayed on the display unit 6.

  A cutting means (spindle unit) 24 for cutting the wafer W held on the chuck table 18 is disposed on the left side of the alignment means 20. The cutting means 24 is configured integrally with the alignment means 20, and both move together in the Y-axis direction and the Z-axis direction.

  The cutting means 24 is configured by mounting a cutting blade (hub blade) 28 on the tip of a rotatable spindle 26 and is movable in the Y-axis direction and the Z-axis direction. The cutting blade 28 is located on the extended line of the imaging means 22 in the X-axis direction.

  Reference numeral 25 denotes conveyance means for conveying the wafer after cutting to the spinner cleaning device 27, and the wafer after the cutting process transferred to the spinner cleaning device 27 is cleaned by the spinner cleaning device 27 and spin-dried.

  Referring to FIG. 2, an exploded perspective view of the cutting means (spindle unit) 24 is shown. FIG. 3 is a perspective view of the spindle unit 24. Reference numeral 25 denotes a spindle housing. A spindle 26 that is rotationally driven by a servo motor (not shown) is rotatably accommodated in the spindle housing 25. The cutting blade 28 is an electroformed blade, and has a cutting edge 28a formed by dispersing diamond abrasive grains in a nickel base material on the outer periphery thereof.

  A screw hole 29 is formed at the end of the spindle 26, and the cutting blade 28 is attached to the front end surface 26 a of the spindle 26 by screwing a screw 31 into the screw hole 29 and tightening.

  A blade cover (wheel cover) 30 covers the cutting blade 28, and a cutting water supply nozzle 32 that extends along the side surface of the cutting blade 28 is attached. Cutting water is supplied to the cutting water nozzle 32 through the pipe 34. The blade cover 30 has screw holes 36 and 38.

  A detachable cover 40 has a cutting water nozzle 42 that extends along the side surface of the cutting blade 28 when attached to the blade cover 30. The cutting water is supplied to the cutting water nozzle 42 via the pipe 44.

  The detachable cover 40 is fixed to the blade cover 30 by inserting the screw 48 into the round hole 46 of the detachable cover 40 and screwing it into the screw hole 36 of the blade cover 30. Thereby, as shown in FIG. 3, the upper half of the cutting blade 28 is covered with the blade cover 30 and the detachable cover 40.

  Reference numeral 50 denotes a blade detection block for detecting chipping or wear of the cutting blade 28a of the cutting blade 28 by a photo interrupter having a light emitting portion and a light receiving portion. A screw 54 is inserted into the round hole 52 and the screw hole 38 of the blade cover 30 is inserted. The blade detection block 50 is attached to the blade cover 30 by being screwed together. Reference numeral 55 denotes an adjustment screw for adjusting the position of the photo interrupter.

  Next, the overall configuration of the spindle unit 24 according to the embodiment of the present invention will be described with reference to a longitudinal sectional view shown in FIG. The spindle housing 25 of the spindle unit 24 has a bore 58, and the spindle 26 is rotatably accommodated in the bore 58.

  The spindle 26 has an annular thrust plate 56 formed integrally. The spindle 26 is rotatably supported in a bore 58 of the spindle housing 25 by a radial air bearing 60 and a thrust air bearing 62.

  An ultrasonic vibrator 64 that applies ultrasonic vibration to the cutting blade 28 is disposed on the spindle 26. The ultrasonic transducer 64 includes an annular piezoelectric element 66 that is polarized in the axial direction of the spindle 26, and annular electrode plates 68 and 70 that are mounted on both polarization surfaces of the piezoelectric element 66.

  The piezoelectric element 66 is composed of piezoelectric ceramics such as barium titanate, lead zirconate titanate, and lithium tantalate. The ultrasonic vibrator 64 configured as described above causes the spindle 26 to generate ultrasonic vibration when AC power having a predetermined frequency is applied to the annular electrode plates 68 and 70 by power supply means described later. A plurality of ultrasonic transducers 64 may be arranged in the axial direction of the spindle 26.

  The spindle unit 24 includes an electric motor 72 that rotationally drives the spindle 26. The electric motor 72 is composed of, for example, a permanent magnet motor. The electric motor 72 includes a rotor 76 made of a permanent magnet mounted on a motor mounting portion 74 formed at an intermediate portion of the spindle 26, and a stator coil 78 disposed on the spindle housing 25 on the outer peripheral side of the rotor 76. Is done.

  In the electric motor 72 configured as described above, the rotor 76 is rotated by applying AC power to the stator coil 78 by a power supply unit (to be described later), whereby the spindle 26 on which the rotor 76 is mounted is rotated.

  The spindle unit 24 further includes power supply means 80 that applies AC power to the ultrasonic transducer 64 and applies AC power to the electric motor 72. The power supply means 80 includes a rotary transformer 82 disposed at one end (right end) of the spindle 26.

  The rotary transformer 82 includes a power receiving unit 84 disposed at the right end of the spindle 26 and a power feeding unit 86 disposed opposite to the power receiving unit 84. The power receiving means 84 includes a rotary core 88 mounted on the spindle 26 and a power receiving coil 90 wound around the rotary core 88.

  The electrode plate 68 of the piezoelectric element 66 is connected to one end of the power receiving coil 90 of the power receiving means 84 configured as described above via a conductive wire, and the other end of the power receiving coil 90 is connected to the other end of the piezoelectric element 66 via the conductive wire. An electrode plate 70 is connected.

  The power feeding means 86 includes a stator core 92 disposed on the outer peripheral side of the power receiving means 84 and a power feeding coil 94 disposed on the stator core 92. AC power is supplied to the power supply coil 94 of the power supply means 86 configured as described above via the electrical wiring 96.

  The power supply unit 80 adjusts the frequency of the AC power supplied to the AC power source 98, the voltage adjusting unit 100 inserted between the AC power source 98 and the power supply coil 94 of the rotary transformer 82, and the power source 86. Means 102, control means 104 for controlling the voltage adjustment means 100 and the frequency adjustment means 102, and input means 106 for inputting the amplitude of the ultrasonic vibration applied to the cutting blade 28 to the control means 104.

  The AC power supply 98 supplies AC power to the stator coil 78 of the electric motor 72 via the control circuit 110 and the electric wiring 108. As the frequency adjusting means 102, a digital function gelator, trade name “DF-1905” provided by NF Circuit Design Block Co., Ltd. can be used. According to DF-1905, the frequency can be appropriately adjusted within a range of 10 Hz to 500 kHz.

  Referring to FIG. 5, a cross-sectional view of the tip portion of the spindle 26 according to the first embodiment of the present invention is shown. According to the present embodiment, the oxide film coating 112 is applied to the tip surface 26 a of the spindle 26.

  The oxide coating 112 is preferably a metal oxide chromium oxide which can be coated at a low temperature, and the Vickers hardness is preferably about Hv 900 or more. Chromium oxide can be coated by plasma spraying, and can be coated by heating at about 150 ° C.

  In order to prevent corrosion of the tip end surface 26a of the spindle 26, metal plating such as hard chrome plating and nickel plating may be considered. However, the present inventors cannot prevent corrosion generated on the tip end surface 26a. Confirmed by experiment.

  In the cutting device 2 of the embodiment of the present invention, a synthetic resin spacer 113 is interposed between the tip surface 26a of the spindle 26 on which the oxide coating 112 is applied and the cutting blade 28, and the cutting blade 28 and the screw 31 are further interposed. The cutting blade 28 is mounted on the spindle 26 by interposing a spacer 115 made of synthetic resin between the screw 31 and screwing the screw 31 into the screw hole 29 and tightening.

  Hereinafter, the operation of the spindle unit 24 of the embodiment of the present invention will be described. AC power is supplied from the power supply means 80 to the stator coil 78 of the electric motor 72. As a result, the electric motor 72 rotates and the spindle 26 rotates, and the cutting blade 28 attached to the tip end surface 26a of the spindle 26 via the oxide coating 112 is rotated.

  On the other hand, the power supply means 80 controls the voltage supply means 100 and the frequency adjustment means 102 by the control means 104 to control the AC power to a predetermined voltage value and adjust the frequency of the AC power to a predetermined frequency to AC power having a predetermined frequency is supplied to the power supply coil 94 of the power supply means 86 constituting the transformer 82.

  When AC power having a predetermined frequency is supplied to the power supply coil 94 as described above, a predetermined frequency is provided between the electrode plate 68 and the electrode plate 70 of the ultrasonic vibrator 64 via the power receiving coil 90 of the rotating power receiving means 84. AC power is applied.

  As a result, the ultrasonic vibrator 64 is ultrasonically vibrated by being repeatedly displaced in the radial direction. This ultrasonic vibration is transmitted to the cutting blade 28 via the spindle 26, and the cutting blade 28 is ultrasonically vibrated in the radial direction.

  In the cutting apparatus 2 of the present embodiment, the cutting material such as a sapphire wafer is cut while the cutting blade 28 is vibrated in the radial direction by the ultrasonic vibrator 64 in this way. The cutting is performed while supplying cutting water. Even if the cutting blade 28 is not sufficiently tightened and the cutting water enters between the cutting blade 28 and the tip surface 26a of the spindle 26, the anti-corrosion agent is applied to the tip surface 26a. Since the oxide coating 112 is applied, the tip surface 26a of the spindle 26 is prevented from being corroded and damaged, and the ultrasonic vibration generated by the ultrasonic vibrator 64 can be appropriately transmitted to the cutting blade 28.

  Referring to FIG. 6, there is shown a cross-sectional view of the spindle tip portion of the second embodiment of the present invention. In this embodiment, in addition to the oxide coating 112 on the tip surface 26 a of the spindle 26, an oxide coating 114 is also applied to the outer peripheral portion of the spindle 26 protruding from the spindle housing 25. Preferably, the oxide coating 114 is comprised of a chromium oxide coating coated by plasma spraying, similar to the oxide coating 112.

24 Cutting means (spindle unit)
25 Spindle housing 26 Spindle 26a Spindle tip surface 28 Cutting blade 64 Ultrasonic vibrator 66 Piezoelectric element 68, 70 Electrode plate 80 Power supply means 112, 114 Oxide coating

Claims (2)

A chuck table for holding the workpiece;
Cutting means having a cutting blade mounted on the tip surface of a spindle that is rotationally driven;
Ultrasonic vibration applying means for applying ultrasonic vibration to the cutting blade;
Moving means for relatively moving the said cutting means and the chuck table, a cutting device provided with,
At least the tip surface of the spindle on which the cutting blade is mounted is coated with a corrosion-resistant agent composed of an oxide having a Vickers hardness of Hv 900 or higher . 2. The cutting apparatus according to claim 1 , wherein the oxide is chromium oxide .

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