JP4731247B2 - Cutting equipment - Google Patents

Description

  The present invention relates to a cutting apparatus that applies ultrasonic vibration to a cutting blade to cut a workpiece such as a semiconductor wafer or an optical device wafer.

  In the 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 devices such as ICs, LSIs, etc. are partitioned in the partitioned regions. Form. Then, the semiconductor wafer is cut along the streets to divide the region in which the device is formed to manufacture individual semiconductor chips. In addition, optical device wafers with gallium nitride compound semiconductors laminated on the surface of sapphire substrates are divided into individual light emitting diodes, laser diodes, CCDs and other optical devices by cutting along the streets. It's being used.

  The above-described cutting along the wafer street is usually performed by a cutting device called a dicer. This cutting apparatus includes a chuck table for holding a workpiece such as a wafer, a cutting means for cutting the workpiece held on the chuck table, and a cutting for relatively moving the chuck table and the cutting means. And feeding means. The cutting means includes a spindle unit having a rotary spindle, a cutting blade mounted on the spindle, and a drive mechanism for driving the rotary spindle to rotate. In such a cutting apparatus, the workpiece held on the cutting blade and the chuck table is relatively cut and fed while rotating the cutting blade at a rotational speed of 20000 to 40000 rpm.

  However, brittle hard materials such as silicon, sapphire, silicon nitride, glass and lithium tantalate are used for the wafer on which the device is formed. There is a problem of lowering. Also, a wafer with high Mohs hardness such as sapphire is very difficult if not impossible to cut with a cutting blade.

In order to solve the above-described problems, an ultrasonic vibrator is disposed on a rotating spindle on which a cutting blade is mounted, and an ultrasonic voltage is applied to the cutting blade by applying an AC voltage to the ultrasonic vibrator. There has been proposed a cutting apparatus that performs cutting. (For example, refer to Patent Document 1.)
In addition, a cutting apparatus has been proposed in which an ultrasonic vibrator is fixed to the surface of the cutting blade and an AC voltage is applied to the ultrasonic vibrator to perform cutting while applying ultrasonic vibration to the cutting blade. Yes. (For example, refer to Patent Document 3.)
JP-A 63-139649 Japanese Patent Laid-Open No. 2004-291636

  Thus, since the load acting on the cutting blade varies depending on the material of the wafer as the workpiece, the cutting depth, the cutting feed rate, the supply condition of the cutting water, etc., the load applied to the cutting blade when the wafer is being cut. It was found by experiments by the present inventors that the amplitude of the applied ultrasonic vibration changes. That is, in the experiments by the present inventors, when the load acting on the cutting blade increases, the power consumption of the ultrasonic vibrator decreases and the amplitude of the ultrasonic vibration applied to the cutting blade decreases and acts on the cutting blade. It was confirmed that when the load was reduced, the power consumption of the ultrasonic vibrator increased and the amplitude of the ultrasonic vibration applied to the cutting blade increased. As described above, when the amplitude of the ultrasonic vibration applied to the cutting blade changes during the cutting of the wafer, the cutting groove is chipped and the quality of the chip is deteriorated.

  The present invention has been made in view of the above-mentioned facts, and a main technical problem thereof is a cutting apparatus that stabilizes the amplitude of ultrasonic vibration applied to a cutting blade so as not to cause chipping in a cutting groove. It is to provide.

In order to solve the above-mentioned main technical problem, according to the present invention, cutting comprising a chuck table for holding a workpiece and a cutting means having a cutting blade for cutting the workpiece held on the chuck table. In the device
An ultrasonic vibrator disposed on a rotary spindle on which the cutting blade is mounted, and applying ultrasonic vibration to the cutting blade; and a power supply means for applying AC power to the ultrasonic vibrator. supply means includes a frequency adjusting means for adjusting the frequency of the AC power output, the power adjustment means for adjusting the supply amount of output AC power, and supplies electric power detecting means for detecting a power value of the output AC power, the Control means for controlling the power adjustment means, and data indicating the relationship between the AC power applied to the ultrasonic transducer in the spindle unit and the amplitude of the cutting blade is input to the control means, and the set AC power the input means for inputting a previously provided control means a predetermined value, said control means power value of the AC power detected by the power supply detecting means, different from the predetermined value set in advance If a feature that controls said power adjustment means so that the predetermined value, the amplitude of the ultrasonic vibration applied to the cutting blade by ultrasonic transducers to stabilize within a predetermined range which are A cutting device is provided.

  According to the present invention, since the amplitude of the ultrasonic vibration applied to the cutting blade is stabilized within a predetermined range, it is possible to prevent the occurrence of chipping caused by fluctuations in the amplitude of the ultrasonic vibration applied to the cutting blade. .

  Hereinafter, a preferred embodiment of a cutting device configured according to the present invention will be described in more detail with reference to the accompanying drawings.

  FIG. 1 shows a perspective view of a cutting device constructed in accordance with the present invention. The cutting device in the illustrated embodiment includes a device housing 2 having a substantially rectangular parallelepiped shape. In the apparatus housing 2, a chuck table 3 for holding a workpiece is disposed so as to be movable in a direction indicated by an arrow X that is a cutting feed direction. The chuck table 3 includes a suction chuck support 31 and a suction chuck 32 disposed on the suction chuck support 31. A workpiece is illustrated on a holding surface which is the upper surface of the suction chuck 32. Suction holding is performed by operating a suction means that does not. The chuck table 3 is configured to be rotatable by a rotation mechanism (not shown). The chuck table 31 is provided with a clamp 33 for fixing a support frame that supports a wafer, which will be described later, via a protective tape as a workpiece. The chuck table 3 configured as described above can be moved in a cutting feed direction indicated by an arrow X by a cutting feed means (not shown).

  The cutting apparatus in the illustrated embodiment includes a spindle unit 4 as cutting means. The spindle unit 4 is mounted on a moving base (not shown) and is adjusted to move in a direction indicated by an arrow Y that is an indexing direction and a direction indicated by an arrow Z that is a cutting direction. The spindle unit 4 will be described with reference to FIG.

  The spindle unit 4 shown in FIG. 2 includes a spindle housing 41, a rotating spindle 42 that is rotatably disposed in the spindle housing 41, and a cutting tool 43 that is attached to the tip of the rotating spindle 42. . The spindle housing 41 is formed in a substantially cylindrical shape and includes a shaft hole 411 penetrating in the axial direction. A rotary spindle 42 that is inserted through a shaft hole 411 formed in the spindle housing 41 includes a tool mounting portion 422 provided with a screw hole 421 at a front end portion thereof, and a central portion thereof in a radial direction. A protruding thrust bearing flange 423 is provided. In this way, the rotary spindle 42 disposed through the shaft hole 411 formed in the spindle housing 41 is rotatably supported by high-pressure air supplied between the inner wall of the shaft hole 411.

  A cutting tool 43 mounted on a tool mounting portion 422 provided at the tip of the rotary spindle 42 includes a resonance member 44 and a cutting blade 45 mounted on the resonance member 44. The resonance member 44 is formed of aluminum in the illustrated embodiment, and has a central large diameter portion 441, a first small diameter portion 442 formed so as to protrude coaxially from one end surface of the central large diameter portion 441, and a large central portion. The second small-diameter portion 443 is formed so as to protrude coaxially from the other end surface of the diameter portion 441. Note that the first small diameter portion 442 and the second small diameter portion 443 are formed to have the same dimensions. A through hole 444 that penetrates the center of the shaft is formed in the resonance member 44 thus formed. In the illustrated embodiment, the cutting blade 45 attached to the resonance member 44 has an electric power obtained by bonding abrasive grains to the end surface of the central large diameter portion 441 of the resonance member 44 on the first small diameter portion 442 side by metal plating such as nickel. It is constituted by a cast blade. The cutting tool 43 configured as described above is configured so that the tightening bolt 46 inserted through the through hole 444 is screwed into the screw hole 421 provided in the tool mounting portion 422 of the rotary spindle 42 to thereby rotate the rotary spindle. 42 is attached. Note that when the cutting tool 43 is mounted on the tool mounting portion 422 of the rotary spindle 42, the tool mounting portion 422 and the first small diameter portion 442 and the second small diameter portion 443 and the head of the tightening bolt 46 are connected. Between the spacers 47 and 47 made of synthetic resin are interposed.

  The spindle unit 4 in the illustrated embodiment includes an electric motor 5 for driving the rotary spindle 42 to rotate. The illustrated electric motor 5 is constituted by a permanent magnet motor. The permanent magnet type electric motor 5 is disposed in a spindle housing 41 on the outer peripheral side of the rotor 51 and a rotor 51 made of a permanent magnet mounted on a motor mounting portion 424 formed in an intermediate portion of the rotary spindle 42. The stator coil 52 is included. In the electric motor 5 configured in this manner, the rotor 51 is rotated by applying AC power to the stator coil 52 by power supply means described later, and the rotating spindle 42 to which the rotor 51 is mounted is rotated.

  The spindle unit 4 in the illustrated embodiment includes an ultrasonic transducer 6 that is disposed on the rotary spindle 42 and applies ultrasonic vibration to the cutting blade 45. The ultrasonic vibrator 6 includes an annular piezoelectric body 61 polarized in the axial direction of the rotary spindle 42 and two annular electrode plates 62 and 63 attached to both side polarization surfaces of the piezoelectric body 61. It has become. The piezoelectric body 61 is made of piezoelectric ceramics such as barium titanate, lead zirconate titanate, and lithium tantalate. The ultrasonic transducer 6 configured as described above is mounted on the rotary spindle 42, and generates ultrasonic vibration when AC power having a predetermined frequency is applied to the electrode plates 62 and 63 by power supply means described later. A plurality of ultrasonic transducers 6 may be arranged in the axial direction.

The spindle unit 4 in the illustrated embodiment includes power supply means 7 that applies AC power to the ultrasonic vibrator 6 and applies AC power to the electric motor 5.
The power supply means 7 includes a rotary transformer 8 disposed at the rear end of the spindle unit 4. The rotary transformer 8 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. ing. 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. One end of the power receiving coil 812 of the power receiving means 81 configured in this way is connected to the electrode plate 61 of the ultrasonic transducer 6, and the other end is connected to the electrode plate 62. The power supply means 82 includes a stator side core 821 disposed on the outer peripheral side of the power reception means 81 and a power supply coil 822 disposed on the stator side core 821. The power supply coil 822 of the power supply means 82 configured in this way is supplied with AC power via the electrical wirings 73 and 74.

  The power supply means 7 in the illustrated embodiment includes an AC power supply 91 for AC power supplied to the power supply coil 822 of the rotary transformer 8, a voltage adjustment means 92 as power adjustment means, and AC power supplied to the power supply means 82. Frequency adjusting means 93 for adjusting the frequency of the first frequency. As the power adjusting means, a current adjusting means may be used instead of the voltage adjusting means 92.

Further, the power supply means 7 in the illustrated embodiment is based on a supply power detection means 94 that detects the power value of the AC power output from the power supply means 7 and a detection signal from the supply power detection means 94. A control means 95 for controlling the voltage adjustment means 92 as the power adjustment means so that the power value of the alternating current power to be a predetermined value, and an input means 96 for inputting set supply power and the like described later to the control means 95. ing. The supplied power detection means 94 includes a voltmeter that detects a voltage value of AC power and an ammeter that detects a current value.
The power supply means 7 shown in FIG. 2 supplies AC power to the stator coil 52 of the electric motor 5 through the control circuit 97 and the electric wirings 521 and 522.

The spindle unit 4 in the illustrated embodiment is configured as described above, and the operation thereof will be described below.
When performing the cutting operation, AC power is supplied from the power supply means 7 to the stator coil 52 of the electric motor 5. As a result, the electric motor 5 rotates and the rotary spindle 42 rotates, and the cutting blade 45 attached to the resonance member 44 of the cutting tool 43 attached to the tip of the rotary spindle 42 is rotated.

  On the other hand, the power supply means 7 controls the voltage adjusting means 92 and the frequency converting means 93 by the control means 95 to control the voltage of the AC power to a predetermined voltage, and the frequency of the AC power is set to a predetermined frequency (for example, 20 kHz). And is supplied to the power supply coil 822 of the power supply means 82 constituting the rotary transformer 8. When AC power having a predetermined frequency is applied to the feeding coil 822 in this way, an AC voltage having a predetermined frequency is applied between the electrode plate 62 and the electrode plate 63 of the ultrasonic transducer 6 via the power receiving coil 812 of the rotating power receiving means 81. Is applied. As a result, the ultrasonic transducer 6 is repeatedly displaced in the radial direction and vibrates ultrasonically. This ultrasonic vibration is transmitted to the resonance member 44 of the cutting tool 43 via the rotary spindle 42, and the resonance member 44 ultrasonically vibrates in the radial direction. Therefore, the cutting blade 45 mounted on the resonance member 44 vibrates ultrasonically in the radial direction.

As described above, when performing a cutting operation by applying ultrasonic vibration to the cutting blade 45, if the load acting on the cutting blade 45 changes, the amplitude of the ultrasonic vibration applied to the cutting blade 45 changes. That is, when the load acting on the cutting blade 45 increases, the impedance increases, the power consumption of the ultrasonic vibrator 6 decreases, the amplitude of the ultrasonic vibration applied to the cutting blade 45 decreases, and it acts on the cutting blade 45. When the load decreases, the impedance decreases, the power consumption of the ultrasonic vibrator 6 increases, and the amplitude of the ultrasonic vibration applied to the cutting blade 45 increases. Thus, if the amplitude of the ultrasonic vibration applied to the cutting blade 45 during cutting changes, the cutting groove is chipped and the quality of the chip is deteriorated. Therefore, the control means 95 of the power supply means 7 controls the supplied power so that the amplitude of the ultrasonic vibration applied to the cutting blade 45 is stabilized within a predetermined range even if the load acting on the cutting blade 45 changes. . The control procedure of the control means 95 will be described with reference to the flowchart shown in FIG.

When performing the above-described cutting operation, the set power supply (WS) (for example, 40 W) is input from the input means 96 to the control means 95 by the operator (step S1).
The control means 95 controls the voltage value (VA) and current value (IA) detected by the voltmeter and ammeter constituting the supply power detection means 94 in step S2, and more specifically, the AC power output from the voltage adjustment means 92. Read the voltage value (VA) and current value (IA). Then, the control means 95 proceeds to step S3, and calculates supply power (WA) from the voltage value (VA) and current value (IA) read in step S2 (WA = VA × IA). Next, the control means 95 proceeds to step S4 and checks whether or not the supply power (WA) obtained in step S3 is equal to the set supply power (WS). If the supplied power (WA) is equal to the set supplied power (WS) in step S4, it is not necessary to change the supplied power, and the process returns to step S2.

  If the supply power (WA) is not equal to the set supply power (WS) in step S4, the control means 95 proceeds to step S5 and determines whether or not the supply power (WA) is greater than the set supply power (WS). To check. If the supply power (WA) is larger than the set supply power (WS) in step S5, the control means 95 proceeds to step S6 and the difference between the supply power (WA) and the set supply power (WS), that is, the surplus power (WB). ) Is calculated (WB = WA-WS). Then, the control means 95 proceeds to step S7, and calculates a voltage value (VB) corresponding to surplus power (WB) (VB = WB ÷ IA). Next, the control means 95 proceeds to step S8 and subtracts the voltage value (VB) corresponding to the surplus power (WB) from the current voltage value (VA) to obtain the set supply power (WS). Calculate (V) (V = VA-VB). Then, the control means 95 proceeds to step S9, changes the set voltage of the voltage adjustment means 92 to (V), and returns to step S2.

  On the other hand, if the supply power (WA) is not greater than the set supply power (WS) in step S5, that is, if the supply power (WA) is less than the set supply power (WS), the control means 95 proceeds to step S10. The difference between the set supply power (WS) and the supply power (WA), that is, the shortage power (WC) is calculated (WC = WS−WA). Then, the control means 95 proceeds to step S11 and calculates a voltage value (VC) corresponding to the insufficient power (WC) (VC = WC ÷ IA). Next, the control means 95 proceeds to step S12 and adds the voltage value (VC) corresponding to the insufficient power (WC) to the current voltage value (VA) to obtain the set supply power (WS). (V) is calculated (V = VA + VC). Then, the control means 95 proceeds to step S9, changes the set voltage of the voltage adjustment means 92 to (V), and returns to step S2.

  As described above, the voltage applied to the cutting blade 45 is controlled by controlling the voltage value of the AC power supplied by the power supply means 7 in response to the change in the load acting on the cutting blade 45, so The amplitude of the sonic vibration can be stabilized within a predetermined range. Note that the amount of radial displacement of the cutting blade 45 increases as the AC power applied to the ultrasonic transducer 6 increases. FIG. 4 is experimental data showing the relationship between the AC power (W) applied to the ultrasonic transducer 6 and the amplitude of the cutting blade 45 in the spindle unit 4 shown in FIG. As can be seen from FIG. 4, when an AC power of 20 W at a frequency of 20 kHz is applied to the ultrasonic vibrator 6, the cutting blade 45 has an amplitude of 5 μm, and cutting is performed when an AC power of 20 W at a frequency of 20 kHz is applied to the ultrasonic vibrator 6. The blade 45 has an amplitude of 6 μm. When an AC power having a frequency of 20 kHz and 40 W is applied to the ultrasonic transducer 6, the cutting blade 45 has an amplitude of 7 μm.

  Referring back to FIG. 1, the description of the cutting apparatus in the illustrated embodiment is for imaging the surface of the workpiece held on the chuck table 3 and detecting the area to be cut by the cutting blade 45. The alignment means 11 is provided. The alignment unit 11 includes an imaging unit including an optical unit such as a microscope or a CCD camera. In addition, the cutting apparatus includes a display unit 12 that displays an image captured by the alignment unit 11.

  In the cassette mounting area 13a of the apparatus housing 2, a cassette mounting table 13 for mounting a cassette for storing a workpiece is disposed. The cassette mounting table 13 is configured to be movable in the vertical direction by lifting means (not shown). On the cassette mounting table 13, a cassette 14 that accommodates the workpiece 100 is mounted. The workpiece 100 accommodated in the cassette 14 has a lattice-like street formed on the surface of the wafer, and devices such as capacitors, LEDs, and circuits are formed in a plurality of rectangular areas partitioned by the lattice-like street. Has been. The workpiece 100 formed in this way is accommodated in the cassette 14 with the back surface adhered to the front surface of the protective tape 102 mounted on the annular support frame 101.

  In the illustrated embodiment, the cutting apparatus is supported by a workpiece 100 (supported on an annular frame 101 via a protective tape 102) accommodated in a cassette 14 placed on a cassette placement table 13. ) To the temporary table 15, the conveying means 17 for conveying the workpiece 100 conveyed to the temporary table 15 onto the chuck table 3, and the workpiece cut on the chuck table 3. A cleaning unit 18 for cleaning the workpiece 100 and a cleaning / conveying unit 19 for conveying the workpiece 100 cut on the chuck table 3 to the cleaning unit 18 are provided.

The operation of the cutting apparatus configured as described above will be briefly described mainly with reference to FIG.
The workpiece 100 accommodated in a predetermined position of the cassette 14 placed on the cassette placement table 13 is positioned at the unloading position by the vertical movement of the cassette placement table 13 by a lifting means (not shown). Next, the unloading means 16 moves forward and backward to unload the workpiece 100 positioned at the unloading position onto the temporary placement table 15. The workpiece 100 carried out to the temporary placement table 15 is transferred onto the chuck table 3 by the turning operation of the transfer means 17. When the workpiece 100 is placed on the chuck table 3, suction means (not shown) is operated to suck and hold the workpiece 100 on the chuck table 3. The support frame 101 that supports the workpiece 100 via the protective tape 102 is fixed by the clamp 33. The chuck table 3 holding the workpiece 100 in this way is moved to a position immediately below the alignment means 11. When the chuck table 3 is positioned immediately below the alignment means 11, the street formed on the workpiece 100 is detected by the alignment means 11, and the spindle unit 4 is moved and adjusted in the direction of the arrow Y, which is the indexing direction. A precision alignment operation with the cutting blade 45 is performed.

  Thereafter, the cutting blade 45 is cut and fed by a predetermined amount in the direction indicated by the arrow Z and rotated in the predetermined direction, while the chuck table 3 holding the workpiece 100 is sucked and held in the direction indicated by the arrow X (cutting blade). The semiconductor wafer 100 held on the chuck table 3 is cut along a predetermined street by the cutting blade 45 by moving at a predetermined cutting feed rate in a direction orthogonal to the rotation axis 45. In this cutting process, AC power is applied to the ultrasonic transducer 6 by the power supply means 7. As a result, as described above, the ultrasonic transducer 6 is ultrasonically vibrated by being repeatedly displaced in the radial direction. This ultrasonic vibration is transmitted to the resonance member 44 of the cutting tool 43 via the rotary spindle 42, and the resonance member 44 ultrasonically vibrates in the radial direction. Therefore, the cutting blade 45 mounted on the resonance member 44 vibrates ultrasonically in the radial direction. Accordingly, since the cutting resistance by the cutting blade 45 is reduced, even if the wafer 100 is a difficult-to-cut material such as sapphire, it can be easily cut. Then, when the load acting on the cutting blade 45 changes during cutting, the supply power is controlled by controlling the voltage value of the AC power supplied by the power supply means 7 in response to the change in the load as described above. The amplitude of the ultrasonic vibration applied to the cutting blade 45 can be stabilized within a predetermined range. Therefore, even if the load acting on the cutting blade 45 changes, cutting can be performed without causing chipping in the cutting groove.

  Although the present invention has been described based on the illustrated embodiment, the present invention is not limited to the embodiment, and various modifications are possible within the scope of the gist of the present invention. For example, in the illustrated embodiment, the voltage adjustment unit 92 is used as the power adjustment unit. However, the AC power supplied in response to the load acting on the cutting blade 45 using the current adjustment unit as the power adjustment unit. The supplied power may be adjusted by controlling the current value. In the illustrated embodiment, the example in which the ultrasonic transducer 6 is disposed on the rotary spindle 4 is shown, but the ultrasonic transducer 6 may be directly attached to the cutting blade 45.

The perspective view of the cutting device comprised according to this invention. Sectional drawing of the spindle unit with which the cutting apparatus shown in FIG. 1 is equipped. The flowchart which shows the control procedure of the control means with which the cutting apparatus shown in FIG. 1 is equipped. Explanatory drawing which shows the relationship between the alternating current power applied to the ultrasonic vibrator with which the spindle unit shown in FIG. 3 is mounted | worn, and the amplitude of the ultrasonic vibration provided to a cutting blade.

Explanation of symbols

2: housing 3: chuck table 4: spindle unit 41: spindle housing 42: rotary spindle 43: cutting tool 44: resonant member 45: the cutting blade 5: electric motor 6: Ultrasonic transducer 7: power supply means 8: Rotary 82: Power supply means 91: AC power supply 92: Voltage adjustment means 93: Frequency adjustment means 94: Supply power detection means 95: Control means 96: Input means 11: Alignment means 12: Display means 13: Cassette mounting table 14: Cassette 15: Temporary table 16: Unloading means 17: Conveying means 18: Cleaning means 19: Cleaning and conveying means

Claims (1)

In a cutting apparatus comprising: a chuck table for holding a workpiece; and a cutting means including a cutting blade for cutting the workpiece held on the chuck table.
An ultrasonic vibrator disposed on a rotating spindle to which the cutting blade is mounted and applying ultrasonic vibration to the cutting blade; and power supply means for applying AC power to the ultrasonic vibrator,
The power supply means includes a frequency adjustment means for adjusting the frequency of the output AC power, a power adjustment means for adjusting the supply amount of the output AC power, and a supply power detection means for detecting the power value of the output AC power. And a control means for controlling the power adjustment means,
The control means has input means for inputting data indicating the relationship between the AC power applied to the ultrasonic vibrator in the spindle unit and the amplitude of the cutting blade, and for inputting a predetermined value of the set AC power to the control means in advance. provided, said control means power value of the AC power detected by the power supply detection means, if you have different predetermined values set in advance, controls the said power adjusting means so that the predetermined value, super A cutting apparatus characterized in that the amplitude of ultrasonic vibration applied to the cutting blade by a sound wave oscillator is stabilized within a predetermined range .

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