JP2013219215A - Method for processing sapphire wafer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for processing a sapphire wafer in which a cutting blade rotating at a high speed can divide the sapphire wafer into chips.SOLUTION: A method for processing a sapphire wafer cuts and divides the sapphire wafer with a cutting blade rotating at a high speed. The method includes: a holding step for holding the sapphire wafer on a holding surface of a chuck table; and a dividing step for cutting the sapphire wafer with the cutting blade rotating at a high speed held at the holding step to divide the sapphire wafer. In the cutting blade, diamond abrasive having a gain diameter of about 10-50 μm are bound by a vitrified bond having a porosity of about 30-70%.

Description

  The present invention relates to a method for processing a sapphire wafer in which a sapphire wafer is divided into chips with a cutting blade that rotates at high speed.

  Single crystal sapphire is used in various devices because of its excellent heat resistance, mechanical stability, chemical stability, light transmission, and the like. However, since the Mohs hardness is very high, there is an aspect that the processing is difficult.

  Therefore, in the case of a sapphire wafer in which an epitaxial layer is laminated on a sapphire wafer and a plurality of LEDs are formed on this epitaxial layer, the sapphire wafer is divided by scribing and cleaving using a diamond bite, and by using a laser beam. Cleavage along the formation and division starting points is selected as the processing method.

  As a method of dividing a sapphire wafer in which a plurality of LEDs are formed using a laser beam into individual LEDs, first and second processing methods described below are known. In the first processing method, a laser beam having a wavelength (for example, 355 nm) having an absorptivity with respect to the sapphire wafer is irradiated to a region corresponding to the planned split line to form a split starting groove serving as a split starting point by ablation processing. Then, an external force is applied thereafter, and the sapphire wafer is divided into individual LEDs.

  In the second processing method, a condensing point of a laser beam having a wavelength that is transmissive to the sapphire wafer (for example, 1064 nm) is positioned inside the sapphire wafer corresponding to the division line, and the laser beam is arranged on the division line. This is a method in which a sapphire wafer is divided into individual LEDs by applying an external force and then applying an external force to divide the sapphire wafer into divisional starting points.

  As a method of using a sapphire wafer, there is a polarizing film holding plate of a projector as an example of an optical component that is utilized by utilizing its characteristics in addition to using as a substrate of an LED (see, for example, JP 2009-003232 A). .

  The polarizing film holding plate is not a mass-produced product like an LED, and since the size of one chip is relatively large, the standard of chipping that occurs during cutting is also large, so the initial investment is a dicing device instead of processing by an expensive laser processing device Is suitable.

JP 2006-319198 A JP 2009-003232 A

  However, in the dicing of a sapphire wafer with a cutting blade, conventionally, a sapphire wafer is divided into individual chips by cutting a line a plurality of times using a resin bond or metal bond type cutting blade. This is because the Mohs hardness of the sapphire wafer is high, and it is very difficult to cut at a high speed with a small chip.

  The present invention has been made in view of these points, and an object of the present invention is to provide a method for processing a sapphire wafer that can be divided into chips with a cutting blade that rotates the sapphire wafer at a high speed.

  According to the present invention, there is provided a sapphire wafer processing method in which a sapphire wafer is cut and divided by a cutting blade that rotates at a high speed, the holding step of holding the sapphire wafer on a holding surface of a chuck table, and the holding step. A cutting step of cutting the cutting blade rotating at high speed into the sapphire wafer to divide the sapphire wafer, and the cutting blade has diamond abrasive grains with a porosity of 30 to about 10 to 50 μm. There is provided a method for processing a sapphire wafer, which is a cutting blade bonded with about 70% vitrified bond.

  The processing method of the sapphire wafer of the present invention uses a cutting blade in which diamond abrasive grains having a particle size of about 10 to 50 μm are bonded by vitrified bonds having a porosity of about 30 to 70%, so that resin bonds and metal bonds can be processed. Compared with cutting using a cutting blade, it is possible to improve the processing speed by about 1.3 to 2 times and the chipping size to about 1/2 to 1/3. This is obtained by a cooling effect and contamination discharging effect by appropriate pores, an appropriate holding power of abrasive grains, and an appropriate consumption.

It is a perspective view of the cutting device suitable for implementing the processing method of this invention. It is a disassembled perspective view which shows a mode that a blade mount is fixed to the front-end | tip of a spindle. It is a disassembled perspective view which shows a mode that a washer blade is mounted | worn with a blade mount. It is a partial cross section side view which shows a division | segmentation step. FIG. 5A is a photograph showing a cutting result cut with a vitrified bond cutting blade according to the present invention, and FIG. 5B is a photograph showing a cutting result cut with a conventional resin bond cutting blade.

  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 device 2 suitable for carrying out the processing method of the present invention. 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, a display monitor 6 such as a CRT on which a guidance screen for an operator and an image captured by an imaging unit described later are displayed is provided.

  A plurality of sapphire wafers 11 to be cut by the cutting apparatus 2 are attached to a dicing tape T attached to an annular frame F, and then housed 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 unit 10 is provided for unloading the wafer 11 from the wafer cassette 8 and loading the wafer after cutting into the wafer cassette 8.

  Between the wafer cassette 8 and the carry-in / out unit 10, a temporary placement area 12, which is an area on which the sapphire wafer 11 to be carried in / out, is temporarily placed, is provided. An alignment mechanism 14 for aligning the wafer 11 at a certain position is provided.

  A transport unit 16 having a swivel arm that sucks and transports the sapphire wafer 11 is disposed in the vicinity of the temporary placement area 12, and the sapphire wafer 11 that has been unloaded and aligned to the temporary placement area 12 is transported. It is sucked by the unit 16 and conveyed onto the chuck table 18 and sucked and held on the chuck table 18.

  The chuck table 18 is configured to be rotatable and reciprocally movable in the X-axis direction by a machining feed mechanism (not shown). Above the movement path of the chuck table 18 in the X-axis direction, an area to be cut by the sapphire wafer 11. An alignment unit 22 is provided for detecting. Reference numeral 20 denotes a clamp for clamping the annular frame F.

  The alignment unit 22 includes an imaging unit 24 that images the surface of the sapphire wafer 11, and can detect a region to be cut by processing such as pattern matching based on an image acquired by imaging. The image acquired by the imaging unit 24 is displayed on the display monitor 6.

  A spindle unit (cutting unit) 26 for cutting the sapphire wafer 11 held on the chuck table 18 is disposed on the left side of the alignment unit 22. The spindle unit 26 is configured integrally with the alignment unit 22 and moves in the Y-axis direction and the Z-axis direction in conjunction with each other.

  The spindle unit 26 is configured by mounting a cutting blade 30 on the tip of a rotatable spindle 28 and is movable in the Y-axis direction and the Z-axis direction. The cutting blade 30 is located on the extended line of the imaging unit 24 in the X-axis direction. The movement of the spindle unit 26 in the Y-axis direction is achieved by an index feed mechanism (not shown).

  Reference numeral 34 denotes a spinner cleaning unit that cleans the sapphire wafer 11 that has been cut. The sapphire wafer 11 that has been cut is transported to the spinner cleaning unit 34 by the transport unit 32, and spin cleaning and spin drying are performed by the spinner cleaning unit 34. Is done.

  Referring to FIG. 2, an exploded perspective view showing a state where the blade mount 40 is attached to the tip of the spindle 28 is shown. A spindle 28 that is rotationally driven by an electric motor (not shown) is rotatably accommodated in a spindle housing 36 of the spindle unit 26. The spindle 28 has a tapered portion 28a and a small distal end portion 28b, and a male screw 38 is formed on the small distal end portion 28b.

  A blade mount 40 includes a boss portion 42 and a fixed flange 44 formed integrally with the boss portion 42, and a male screw 46 is formed on the boss portion 42. Further, the blade mount 40 has a mounting hole 47.

  In the blade mount 40, the mounting hole 47 is inserted into the tip small diameter portion 28 b and the tapered portion 28 a of the spindle 28, and the nut 48 is screwed into the male screw 46 and tightened, so that the tip small diameter of the spindle 28 is shown in FIG. It is attached to the part 28b.

  Referring to FIG. 3, there is shown an exploded perspective view showing a state where the washer-like cutting blade 30 is mounted on the blade mount 40 fixed to the tip of the spindle 28. The washer-shaped cutting blade 30 is configured by bonding diamond abrasive grains having a particle size of about 10 to 50 μm with vitrified bonds having a porosity of about 30 to 70%.

  Such a vitrified bond cutting blade 30 is prepared by mixing ceramic or glassy abrasive grains, organic abrasive grains, and diamond abrasive grains, as described in, for example, Japanese Patent Publication No. 6-24700. It is manufactured by baking.

  The cutting blade 30 is inserted into the boss portion 42 of the blade mount 40, the detachable flange 50 is further inserted into the boss portion 42, and the fixing nut 52 is screwed into the male screw 48 and tightened, whereby the cutting blade 30 is fixed to the fixing flange 44. And is attached to the spindle 28 by being sandwiched from both sides by the detachable flange 50.

  Referring to FIG. 4, there is shown a partial cross-sectional side view showing a state in which the sapphire wafer 11 is divided into individual chips by a vitrified bond cutting blade 30. Before performing this division step, the imaging unit 24 images the surface of the sapphire wafer 11 and performs alignment for detecting a division planned line extending in the first direction.

  After the alignment in the first direction, the chuck table 18 is rotated by 90 degrees, and the alignment for detecting the division line extending in the second direction orthogonal to the first direction is similarly performed.

  After the alignment, the cutting blade is cut into the sapphire wafer 11 while rotating the cutting blade in the A direction at high speed, and the sapphire wafer 11 is completely cut and cut while the chuck table 18 is fed in the X-axis direction at a machining feed rate of 3 mm / s, for example. A groove 13 is formed. The dividing lines extending in the first direction while being indexed and fed in the Y-axis direction are cut one after another.

  Next, the chuck table 18 is rotated 90 degrees, and the division line to be extended in the second direction is cut one after another while being indexed and fed in the Y-axis direction to divide the sapphire wafer 11 into individual chips.

  In the processing method of the sapphire wafer of this embodiment, a vitrified bond blade in which diamond abrasive grains having a particle size of about 10 to 50 μm are bonded by vitrified bonds having a porosity of about 30 to 70% is used as the washer-like cutting blade 30. By adopting, the processing speed can be improved by about 1.3 to 2 times, and the chipping size can be improved to about 1 to 〜.

  Referring to FIG. 5, there is shown a comparison of the cutting results with the vitrified bond blade of the present invention and the cutting results with a conventional range bond blade. FIG. 5A shows a photograph of the cutting result with the vitrified bond blade of the present invention, and FIG. 5B shows a photograph of the cutting result with the conventional resin bond blade.

  For vitrified bond blades, diamond abrasive grains of # 400 mesh were used and processed at a feed rate of 3 mm / s to cut a 0.7 mm thick sapphire wafer. For resin bond blades, # 240 mesh This is a result of cutting a sapphire wafer having a thickness of 0.7 mm at a processing feed rate of 2 mm / s.

  Here, the resin bond blade employs # 240 mesh diamond abrasive grains because the sapphire wafer cannot be processed with fine abrasive grains such as # 400 mesh.

  In the conventional example shown in FIG. 5B, a large chip as shown by reference numeral 15 occurs. In contrast, it can be seen that in the processing method of the present invention using the vitrified bond blade shown in FIG.

11 Sapphire wafer 13 Cutting groove 15 Chip 18 Chuck table 24 Imaging unit 26 Spindle unit (cutting unit)
28 Spindle 30 Cutting blade 40 Blade mount 50 Removable flange

Claims (1)

A method for processing a sapphire wafer, which is cut by a cutting blade rotating at high speed and divided.
Holding step for holding the sapphire wafer on the holding surface of the chuck table;
A dividing step of dividing the sapphire wafer by cutting the cutting blade rotating at high speed into the sapphire wafer held in the holding step,
The sapphire wafer processing method, wherein the cutting blade is a cutting blade in which diamond abrasive grains having a particle size of about 10 to 50 μm are bonded by vitrified bonds having a porosity of about 30 to 70%.

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