CN103358408A - Processing method for sapphire wafer - Google Patents

Abstract

The invention provides a processing method for a sapphire wafer, which can divide the sapphire wafer into chips by using a high-speed rotating cutting tool. The processing method of the sapphire wafer is a method of cutting and dividing the sapphire wafer with a high-speed rotating cutting tool, and it is characterized in that the processing method of the sapphire wafer has: a holding step, and in the holding step, the sapphire wafer is held on the holding surface of the chuck table; and a dividing step in which the cutting tool rotated at a high speed is cut into the sapphire wafer held in the holding step to divide the sapphire wafer, The above-mentioned cutting tool is a cutting tool in which diamond abrasive grains with a particle size of about 10-50 μm are bonded with a vitrified bond with a porosity of about 30-70%.

Description

Processing method of sapphire wafer

technical field

The invention relates to a processing method of a sapphire wafer, which is a method for dividing the sapphire wafer into chips by using a high-speed rotating cutting tool.

Background technique

Single crystal sapphire is used in various devices due to its excellent heat resistance, mechanical stability, chemical stability and light transmission. However, since the Mohs hardness is very high, there is a side where processing is difficult.

Therefore, in the case of laminating an epitaxial layer on a sapphire wafer and forming a plurality of LEDs on the sapphire wafer, as a processing method for dividing the sapphire wafer, scribing and cutting with a diamond turning tool and forming a starting point for division with a laser beam are selected. And the method of cutting along the starting point of the segmentation.

As a method of dividing a sapphire wafer formed with a plurality of LEDs into individual LEDs using a laser beam, the first and second processing methods described below are known. The first processing method is a method of irradiating a laser beam with an absorbing wavelength (for example, 355 nm) to a sapphire wafer to an area corresponding to a planned division line, forming a division starting groove as a division starting point by ablation processing, and then External force is applied to separate the sapphire wafer into individual LEDs.

The second processing method is a method in which a laser beam of a wavelength (for example, 1064 nm) that is transparent to the sapphire wafer is positioned at the inside of the sapphire wafer corresponding to the planned dividing line, and the laser is irradiated along the planned dividing line. beam to form a modified layer inside the wafer, and then apply an external force to split the sapphire wafer into individual LEDs with the modified layer as the starting point for splitting.

As a method of using a sapphire wafer, in addition to being used as a substrate of an LED, there is also a polarizer holding plate of a projector as an example of an optical component that fully utilizes its characteristics (for example, refer to Japanese Patent Application Laid-Open No. 2009-003232 ).

The holding plate of the polarizer is not a mass-produced product like LED, and since the size of one chip is relatively large, the specifications of the chips generated during cutting are also large, so it is suitable for processing with a cutting device and not suitable for the initial stage of use. Invest in expensive laser processing equipment for processing.

Patent Document 1: Japanese Patent Laid-Open No. 2006-319198

Patent Document 2: Japanese Patent Laid-Open No. 2009-003232

However, in the dicing of a sapphire wafer using a cutting blade, a resin-bonded or metal-bonded cutting blade has conventionally been used to divide the sapphire wafer into individual chips by cutting multiple times in one line. This is because the sapphire wafer has a high Mohs hardness, and it is very difficult to reduce the chip and cut it quickly.

Contents of the invention

The present invention has been made in view of such circumstances, and an object of the present invention is to provide a method for processing a sapphire wafer capable of dividing the sapphire wafer into chips by using a high-speed rotating cutting tool.

According to the present invention, a kind of processing method of sapphire wafer is provided, the processing method of described sapphire wafer is to utilize the cutting tool of high-speed rotation to cut sapphire wafer to divide it, it is characterized in that, the processing method of described sapphire wafer has: a holding step of holding the sapphire wafer on a holding surface of a chuck table; and a dividing step of cutting the cutting tool rotating at a high speed into the holding step The sapphire wafer held in the center is used to divide the sapphire wafer, and the cutting tool is a cutting tool that combines diamond abrasive grains with a particle size of about 10 to 50 μm with a vitrified bond with a porosity of about 30 to 70%. .

The processing method of the sapphire wafer of the present invention adopts a cutting tool that the diamond abrasive grains with a particle diameter of about 10 to 50 μm are combined with a vitrified bond with a porosity of about 30 to 70%. Therefore, it is different from using a resin bond or a metal Compared with the cutting of the cutting tool of the bond, the processing speed can be improved by about 1.3 to 2 times, and the chip size can be improved by about 1/2 to 1/3. This is achieved by a moderate cooling effect and dirt discharge effect due to the pores, as well as a moderate retention force and a moderate consumption of abrasive grains.

Description of drawings

Fig. 1 is a perspective view of a cutting device suitable for carrying out the processing method of the present invention.

Fig. 2 is an exploded perspective view showing a state in which the tool holder is fixed to the tip of the main shaft.

Fig. 3 is an exploded perspective view showing a state in which a washer-shaped cutter is attached to a cutter holder.

Fig. 4 is a partial sectional side view showing a dividing step.

(A) of FIG. 5 is a photograph showing the cutting result of cutting with a cutting tool using a vitrified bond according to the present invention, and (B) of FIG. Photo of the cutting result of the chipping.

Label description

11: sapphire wafer;

13: cutting groove;

15: Gap;

18: chuck table;

24: shooting unit;

26: Spindle unit (cutting unit);

28: spindle;

30: cutting tool;

40: knife holder;

50: loading and unloading flange.

Detailed ways

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 implementing the machining method of the present invention. On the front side of the cutting device 2 is provided an operation panel 4 for an operator to input instructions to the device such as machining conditions. A display 6 such as a CRT is provided on the upper part of the device, and the display 6 displays a guidance screen for guiding an operator and an image captured by an imaging unit described later.

After the sapphire wafer 11 to be cut by the cutting device 2 is attached to the dicing tape T attached to the ring frame F, a plurality of sapphire wafers are accommodated in the wafer cassette 8 shown in FIG. 1 . The wafer cassette 8 is placed on a cassette elevating device 9 capable of moving up and down.

A carry-out unit 10 for carrying out wafers 11 before cutting from the cassette 8 and carrying wafers after cutting into the cassette 8 is disposed behind the cassette 8 .

A temporary storage area 12 is provided between the wafer cassette 8 and the loading/unloading unit 10. The temporary storage area 12 is used as an area for temporarily placing the sapphire wafer 11 which is the target of loading/unloading. An alignment mechanism 14 for aligning the wafer 11 with a fixed position.

Near the temporary storage area 12 is equipped with a transfer unit 16 with a rotary arm, the transfer unit 16 is used to absorb and transfer the sapphire wafer 11, and the sapphire wafer 11 carried out to the temporary storage area 12 and aligned The unit 16 is sucked and transported onto the chuck table 18 , and the sapphire wafer 11 is sucked and held on the chuck table 18 .

The chuck table 18 is configured to be rotatable and capable of reciprocating movement in the X-axis direction by a processing feed mechanism not shown, and a calibration unit 22 is arranged above the movement path of the chuck table 18 in the X-axis direction, so that The above-mentioned calibration unit 22 is used to detect the area to be cut of the sapphire wafer 11 . Reference numeral 20 is a clamp for clamping the ring frame F. As shown in FIG.

The calibration unit 22 includes an imaging unit 24 for imaging the surface of the sapphire wafer 11 , and the calibration unit 22 can detect a region to be ablated by processing such as pattern matching based on an image obtained by imaging. Images acquired by the imaging unit 24 are displayed on the display 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 main shaft unit 26 and the calibration unit 22 are integrally formed, and the two move along the Y-axis and the Z-axis in a linked manner.

The spindle unit 26 is constituted by attaching a cutting tool 30 to the tip of a rotatable spindle 28 , and the spindle unit 26 is movable in the Y-axis direction and the Z-axis direction. The cutting tool 30 is located on the extension line of the imaging unit 24 in the X-axis direction. The movement of the spindle unit 26 in the Y-axis direction is realized by an index feed mechanism not shown.

Reference numeral 34 is a spin cleaning unit for cleaning the sapphire wafer 11 after the cutting process is completed. The sapphire wafer 11 after the cutting process is transported to the spin cleaning unit 34 by the transport unit 32, and the spin cleaning unit 34 performs spin cleaning and cleaning. Spin dry.

Referring to FIG. 2 , there is shown an exploded perspective view showing the condition in which the tool holder 40 is mounted to the end of the main shaft 28 . A main shaft 28 is rotatably accommodated in a main shaft case 36 of the main shaft unit 26 , and the main shaft 28 is rotationally driven by an electric motor not shown. The main shaft 28 has a tapered portion 28a and a small-diameter tip portion 28b, and an external thread 38 is formed on the small-diameter tip portion 28b.

Reference numeral 40 is a tool holder composed of a boss portion 42 and a fixing flange 44 integrally formed with the boss portion 42 , and an external thread 46 is formed on the boss portion 42 . Also, the tool holder 40 has a mounting hole 47 .

The mounting hole 47 is inserted into the end small diameter portion 28b and the tapered portion 28a of the main shaft 28, and the nut 48 is screwed with the external thread 46 and tightened, so that the tool holder 40 is installed on the end small diameter of the main shaft 28 as shown in FIG. 3 Section 28b.

Referring to FIG. 3 , there is shown an exploded perspective view showing a state in which a washer-shaped cutting tool 30 is attached to a tool holder 40 fixed to the end of the main shaft 28 . The washer-shaped cutting tool 30 is formed by bonding diamond abrasive grains with a particle size of about 10 to 50 μm with a vitrified bond with a porosity of about 30 to 70%.

Such a cutting tool 30 using a vitrified bond is, for example, as described in Japanese Patent Publication No. 6-24700, in which ceramic or vitreous abrasive grains, organic abrasive grains and diamond abrasive grains are mixed and fired at a predetermined temperature. manufactured in a manner.

The cutting tool 30 is inserted into the boss portion 42 of the tool holder 40, then the loading and unloading flange 50 is inserted into the boss portion 42, and the fixing nut 52 is screwed to the external thread 46 and tightened, so that the cutting tool 30 is fixed by the fixing flange 44. Mounted to the main shaft 28 by clamping and attaching and detaching flanges 50 from both sides.

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 cutting tool 30 using a vitrified bond. Before implementing the dividing step, calibration is performed: the surface of the sapphire wafer 11 is photographed by the imaging unit 24, and the planned dividing line extending along the first direction is detected.

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

After calibration, the cutting tool is rotated in the A direction at a high speed while cutting into the sapphire wafer 11, and the chuck table 18 is processed and fed in the X-axis direction at a processing feed rate of, for example, 3 mm/s to completely cut the sapphire. Wafer 11 forms cutting grooves 13 . The planned dividing lines extending in the first direction are sequentially cut while indexing and feeding in the Y direction.

Next, the chuck table 18 is rotated by 90 degrees, and the dividing line extending in the second direction is sequentially cut while indexing and feeding in the Y-axis direction, thereby dividing the sapphire wafer 11 into individual chips.

In the processing method of the sapphire wafer of the present embodiment, a vitrified bond tool formed by bonding diamond abrasive grains with a particle size of about 10 to 50 μm with a vitrified bond with a porosity of about 30 to 70% is used as a washer-shaped The cutting tool 30 can improve the processing speed by about 1.3 to 2 times, and improve the chips by about 1/2 to 1/3.

Referring to (A) and (B) of FIG. 5 , there is shown a comparison between chip processing results using a vitrified bond tool of the present invention and cutting processing results using a conventional resin bond tool. (A) of FIG. 5 shows a photo of a result of cutting with a vitrified bond tool of the present invention, and (B) of FIG. 5 shows a photo of a result of cutting with a conventional resin bond tool.

For the vitrified bond tool, use #400 purpose diamond abrasive grains, the result is to cut off the sapphire wafer with a thickness of 0.7mm at a processing feed rate of 3mm/s. For the resin bond tool, use #240 purpose diamond abrasive grains. As a result, a sapphire wafer with a thickness of 0.7 mm was cut at a processing feed rate of 2 mm/s.

Here, although #240 mesh diamond abrasive grains are used for the resin bond tool, this is because fine abrasive grains such as #400 mesh cannot be used to process sapphire wafers.

In the conventional example shown in (B) of FIG. 5 , a large notch is generated as indicated by reference numeral 15 . On the other hand, in the machining method of the present invention using a vitrified bond tool shown in FIG. 5(A), it can be seen that almost no chipping occurs.

Claims (1)

1. the processing method of a sapphire wafer, the processing method of described sapphire wafer are to utilize the method for cutting tool cutting sapphire wafer so that it is cut apart of High Rotation Speed, it is characterized in that,

The processing method of described sapphire wafer possesses:

Keep step, in described maintenance step, described sapphire wafer is remained in the maintenance face of chuck table; With

Segmentation procedure, in described segmentation procedure, the described sapphire wafer that the described cutting tool incision of High Rotation Speed is kept in described maintenance step is cut apart described sapphire wafer,

Described cutting tool is that the diamond abrasive grain that particle diameter is approximately 10～50 μ m is utilized the porosity is the cutting tool that about 30～70% vitrified bond is combined into.

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