JP2014123601A - Grinding apparatus and method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a grinding apparatus and method capable of reducing a risk of breakage of a workpiece or a grinding wheel.SOLUTION: A grinding apparatus for grinding a workpiece, includes: grinding means having a chuck table for rotatably holding the workpiece, a spindle, and a grinding wheel attached to the spindle and grinding the workpiece held by the chuck table; processing feed means for relatively feeding the grinding means for processing in a direction coming close to or separating from the workpiece held by the chuck table; vibration signal generating means for detecting vibration acting on the grinding means to generate a vibration signal corresponding to the detected vibration; and control means for controlling the processing feed by the processing feed means on the basis of the vibration signal generated in the vibration signal generating means.

Description

  The present invention relates to a grinding apparatus and a grinding method 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 widely used in various 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.

  When grinding a workpiece such as a wafer, the grinding wheel is brought into contact with the workpiece held on the chuck table while rotating the grinding wheel, and the grinding wheel is moved at a desired grinding feed rate by the grinding feed mechanism. The workpiece is ground while being fed downward.

  The grinding feed speed is appropriately set according to the type of grinding wheel used, the type of workpiece to be ground, and the like. For example, when grinding semiconductor wafers made of silicon, a relatively fast grinding feed rate is set, and when grinding brittle hard materials such as sapphire and Altic, a relatively slow grinding feed rate is set. The

JP 2003-068690 A JP 2011-189456 A

  The setting of the grinding feed rate is important. For example, when grinding is started with the grinding feed rate set too high for the workpiece, the grinding wheel is focused on while grinding the workpiece. Abnormalities such as crushing and clogging occur and the grinding load increases. If grinding feed is continued at a constant speed in this state, the workpiece and the grinding wheel may be damaged.

  This invention is made | formed in view of such a point, The place made into the objective is providing the grinding apparatus and grinding method which can reduce a possibility that a to-be-processed object and a grinding wheel will be damaged. .

  According to the first aspect of the present invention, there is provided a grinding apparatus for grinding a workpiece, the chuck table holding the workpiece rotatably, a spindle, and the spindle mounted on the spindle and held by the chuck table. A grinding wheel having a grinding wheel for grinding the workpiece; a processing feeding means for relatively feeding the grinding means in a direction approaching and separating from the workpiece held on the chuck table; A vibration signal generating means for detecting a vibration acting on the grinding means and generating a vibration signal corresponding to the detected vibration, and a machining feed by the machining feed means based on the vibration signal generated by the vibration signal generating means And a control means for providing a grinding device.

  Preferably, the vibration signal generation means is an ultrasonic vibrator that generates a voltage corresponding to vibration acting on the grinding means disposed in the grinding means, and a power transmission that is connected to the ultrasonic vibrator and transmits the voltage to the control means. Means.

  According to a third aspect of the present invention, there is provided a grinding method for grinding a workpiece by the grinding apparatus according to the first or second aspect, wherein the workpiece is held by the chuck table, and the chuck table holds the workpiece. A grinding step in which the grinding wheel that rotates while rotating the processed workpiece is brought into contact with the workpiece, and the grinding means is processed and fed by the processing feeding means to grind the workpiece, and the grinding step A vibration signal detecting step for detecting a vibration signal generated by the vibration signal generating means during the execution of the processing, and in the grinding step, the machining feed means based on the vibration signal detected in the vibration signal detecting step There is provided a grinding method characterized by controlling the machining feed of the steel.

  In general, when the machining load increases, the vibration acting on the grinding means increases, and when the machining load decreases, the vibration acting on the grinding means decreases. Therefore, the grinding device of the present invention detects vibration acting on the grinding means, generates a vibration signal corresponding to the detected vibration, and performs machining feed by the machining feed means based on the generated vibration signal. Control means for controlling is provided.

  Therefore, when a vibration signal indicating that the vibration is large can be detected, the machining feed by the machining feed means can be decelerated, so that the machining feed is not continued at a constant speed in a state where the machining load is increased, The possibility that the workpiece and the grinding wheel are damaged can be reduced.

  In addition, when a vibration signal indicating that the vibration is smaller than a predetermined value is detected, the machining feed rate by the machining feed means can be increased, so that the grinding time can be shortened and productivity can be improved. It becomes.

1 is a perspective view of a grinding apparatus according to an embodiment of the present invention. It is a partial cross section front view of the grinding unit of this invention embodiment. It is a disassembled perspective view of the wheel mount with which the front-end | tip part of the spindle was mounted | worn. It is a disassembled perspective view which shows a mode that a grinding wheel is mounted | worn with a wheel mount. It is a time chart which shows progress of the detection voltage during grinding of a workpiece.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is an external perspective view of a grinding apparatus 2 according to an embodiment of the present invention. Reference numeral 4 denotes a housing of the grinding device 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, an electric motor 20 that rotates the spindle 18, a wheel mount 22 that is fixed to the tip of the spindle 18, and an annular screw-tightened to the wheel mount 22. And a grinding wheel 24 having a plurality of grinding wheels.

  The grinding apparatus 2 includes a grinding unit feed mechanism 34 including a ball screw 30 and a pulse motor 32 that move the grinding unit 10 in the vertical direction along the pair of guide rails 8. When the pulse motor 32 is driven, the ball screw 30 is rotated and the moving base 16 is moved in the vertical direction.

  A recess 4 a is formed on the upper surface of the housing 4, and a chuck table mechanism 36 is disposed in the recess 4 a. The chuck table mechanism 36 has a chuck table 38 and is moved in the Y-axis direction between a wafer attaching / detaching position A and a grinding position B facing the grinding unit 10 by a moving mechanism (not shown). 40 and 42 are bellows. On the front side of the housing 4, an operation panel 44 through which an operator of the grinding device 2 inputs grinding conditions and the like is disposed.

  As shown in FIGS. 2 and 3, a wheel mount 22 is fixed to the tip of the spindle 18. The wheel mount 22 has a wheel base mounting part 22a and an ultrasonic transducer mounting part 22b surrounding the wheel base mounting part 22a.

  Four bolt insertion holes 47 are provided in the wheel base mounting portion 22a. Furthermore, four holes 49 communicating with the through hole 21 of the spindle 18 are formed in the wheel base mounting portion 22a so as to open to the outer peripheral surface.

  The ultrasonic transducer mounting portion 22b of the wheel mount 22 is formed with a step below the upper surface of the wheel base mounting portion 22a, and has four circumferential portions at the boundary with the wheel base mounting portion 22a. A circular slit 48 is formed penetrating from the upper surface to the lower surface.

  On the upper surface of the ultrasonic transducer mounting portion 22b formed in this way, four arc-shaped ultrasonic transducers 46 are firmly bonded to the positions corresponding to the four arc-shaped slits 48 by an adhesive. .

As the ultrasonic transducer 46, 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.

  As shown in FIGS. 2 and 4, the ultrasonic transducer 46 bonded to the ultrasonic transducer mounting portion 22 b of the wheel mount 22 includes the through hole 21 and the wheel formed in the axial direction at the center of the spindle 18, respectively. A conductive wire 61 wired through a hole 49 formed in the base mounting portion 22a is connected to a power feeding coil 78 of a power transmission means (rotary transformer) 70.

  The rotary transformer 70 includes a power feeding unit 72 disposed at the upper end of the spindle 18 and a power receiving unit 74 disposed to face the power feeding unit 72. The power supply means 72 includes a rotor core 76 attached to the spindle 18 and a power supply coil 78 wound around the rotor core 76.

  The power receiving unit 74 includes a stator core 80 disposed on the outer peripheral side of the power feeding unit 72 and a power receiving coil 82 disposed on the stator core 80. The power receiving coil 82 of the power receiving means 74 configured as described above is connected to the controller 86 via the wiring 84. The controller 86 includes a voltage detection unit 88 and a comparison unit 90 that compares the voltage detected by the voltage detection unit 88 with a predetermined voltage.

  Referring again to FIG. 4, the grinding wheel 24 includes an annular wheel base 50 and a plurality of grinding wheels 52 fixed to the outer periphery of the lower surface of the wheel base 50. The wheel base 50 is formed with four screw holes 51 corresponding to the bolt insertion holes 47 formed in the wheel mount 22.

  The grinding wheel 24 is screwed into the screw holes 51 formed in the wheel base 50 by screwing the fastening bolts 53 respectively inserted into the bolt insertion holes 47 provided in the wheel base mounting portion 22 a of the wheel mount 22. The wheel mount 22 is detachably attached.

  Referring back to FIG. 2, the grinding unit 10 includes an electric motor 20 that rotates the spindle 18. The electric motor 20 is composed of, for example, a permanent magnet motor. The electric motor 20 includes a rotor 58 made of a permanent magnet mounted on a motor mounting portion 56 formed at an intermediate portion of the spindle 18, and a stator coil 60 disposed on the spindle housing 12 at the outer peripheral portion of the rotor 58. Is done.

  The stator coil 60 of the electric motor 20 is connected to a drive circuit 64 via an electric wiring 66, and the drive circuit 64 is connected to an AC power supply 62. When AC power is applied to the stator coil 60 of the electric motor 20 by the drive circuit 64, the rotor 58 rotates and the spindle 18 to which the rotor 58 is attached is rotated.

  The grinding operation of the grinding device 2 configured as described above will be described below. A sapphire wafer having a protective tape affixed to the surface is sucked and held on the chuck table 38 positioned at the wafer attachment / detachment position A shown in FIG. Next, the chuck table 38 is moved in the Y-axis direction and positioned at the grinding position B.

  For the sapphire wafer thus positioned, while rotating the chuck table 38 at, for example, 300 rpm, the grinding wheel 24 is rotated in the same direction as the chuck table 38, for example, at 1000 rpm, and a grinding unit feed mechanism (work feed means) ) 34 is operated to bring the grinding wheel 52 into contact with the back surface of the wafer.

  Then, the wafer is ground while the grinding wheel 24 is ground and fed downward at a predetermined grinding feed rate (processing feed rate). When grinding is performed, vibration is generated, and a voltage is generated in the ultrasonic vibrator 46 bonded to the wheel mount 22 in accordance with the vibration.

  This voltage is supplied to the power supply coil 78 of the power transmission means 70 via the conductive wire 61, and a voltage is generated in the power reception coil 82 according to this voltage. This voltage is input to the controller 86 via the wiring 84 and is detected by the voltage detector 88 of the controller 86.

  The voltage detected by the voltage detector 88 is compared with a predetermined voltage by the comparator 90. This predetermined voltage includes the first voltage value V1, the second voltage value V2, and the third voltage value V3 shown in the time chart of FIG.

  Here, when the voltage becomes equal to or higher than the first voltage value V1, the grinding feed is decelerated. When the voltage becomes equal to or lower than the second voltage value V2, the grinding feed speed is increased. Further, when the voltage becomes equal to or higher than the third voltage value V3 higher than the first voltage value V1, the grinding feed is stopped and the grinding unit 10 is retracted from the workpiece.

  The time chart of FIG. 5 shows a change in voltage detected by the voltage detector 88 from the machining start time T1 to the machining end time T2. If the detected voltage exceeds the first voltage value V1, it is determined that the vibration detected by the ultrasonic vibrator 46 has exceeded the allowable value, and the pulse motor 32 is controlled to decrease the grinding feed speed.

  On the other hand, when the detected voltage becomes equal to or lower than the second voltage value V2, the pulse motor 32 is controlled to increase the grinding feed speed. In this way, the workpiece is ground so that the voltage generated by the ultrasonic transducer 46 is controlled within the range of the first voltage value V1 or less and the second voltage value V2 or more.

  Therefore, when a vibration signal indicating that the vibration is large is generated, this can be detected by the first voltage value V1, and the grinding feed speed by the grinding feed mechanism 34 can be reduced, so that the grinding load is increased. Grinding feed is not continued at a constant speed, and the risk of damage to the workpiece and the grinding wheel 24 can be reduced.

  Further, when a vibration signal indicating that the vibration is small is generated, it can be detected by the second voltage value V2, and the grinding feed speed by the grinding feed mechanism 34 can be increased, so that the grinding time is shortened. Productivity.

  In the above-described embodiment, the workpiece is described as a sapphire wafer. However, the grinding apparatus and the grinding method of the present invention are not limited to a sapphire wafer, and a semiconductor wafer, an Altic substrate, a glass substrate. The present invention can be similarly applied to other workpieces.

2 Grinding device 10 Grinding unit 18 Spindle 20 Electric motor 22 Wheel mount 24 Grinding wheel 32 Pulse motor 34 Grinding feed mechanism 38 Chuck table 46 Ultrasonic vibrator 70 Power transmission means 86 Controller 88 Voltage detection unit 90 Comparison unit

Claims (3)

A grinding device for grinding a workpiece,
A chuck table that rotatably holds the workpiece;
A grinding means having a spindle, and a grinding wheel that is mounted on the spindle and grinds a workpiece held on the chuck table;
Processing feed means for relatively feeding the grinding means in a direction approaching and separating from the workpiece held on the chuck table;
Vibration signal generating means for detecting vibration acting on the grinding means and generating a vibration signal corresponding to the detected vibration;
Control means for controlling machining feed by the machining feed means based on the vibration signal generated by the vibration signal generating means;
A grinding apparatus comprising: The vibration signal generating means is an ultrasonic vibrator that is arranged in the grinding means and generates a voltage corresponding to vibration acting on the grinding means;
The grinding apparatus according to claim 1, further comprising: a power transmission unit connected to the ultrasonic transducer and transmitting a voltage to the control unit. A grinding method for grinding a workpiece with the grinding apparatus according to claim 1 or 2,
A holding step for holding a workpiece on the chuck table;
A grinding step in which the grinding wheel rotating while rotating the workpiece held on the chuck table is brought into contact with the workpiece, and the grinding means is processed and fed by the processing feeding means to grind the workpiece. When,
A vibration signal detecting step of detecting a vibration signal generated by the vibration signal generating means during the grinding step;
In the grinding step, the machining feed of the machining feed means is controlled based on the vibration signal detected in the vibration signal detection step.

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