JP2009241119A - Dividing method of crystalline material, and its apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide the dividing method of a crystalline material, and its apparatus for reforming a laser beam irradiated portion in a dividable state by irradiating a laser beam transmitting the crystalline material along the division scheduled line of the crystalline material. <P>SOLUTION: In the dividing method of the crystalline material, and its apparatus, a laser beam oscillator 4 is provided, which oscillates laser beam L transmitting the crystalline material 2 as a workpiece, and a laser beam irradiated portion is reformed in a dividable state by irradiating the laser beam L along the division scheduled line of the crystalline material. In the present invention, the apparatus includes a machining head 6 which jets the liquid toward the crystalline material in a liquid column W shape, a liquid feed means 7 for feeding the high-pressure liquid to the machining head, and a laser beam introducing means 10 for introducing the laser beam oscillated from the laser beam oscillator in the liquid column. The laser beam irradiated portion can be reformed in a dividable state by making the laser beam pass through the liquid jetted in the liquid column state, and guiding it to the crystalline material for irradiation with the laser beam while relatively moving the liquid jetted in the liquid column shape along the division scheduled line of the crystalline material. In the present invention, highly accurate focusing is not needed, and the crystalline material such as sapphire can be reformed in a dividable state. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  More particularly, the present invention relates to a method and apparatus for cleaving a crystalline material, and more specifically, irradiates a laser beam that passes through the crystalline material along a planned cutting line of the crystalline material so that the irradiated portion can be cleaved. The present invention relates to a method and apparatus for cleaving a crystalline material to be modified.

Conventionally, for example, YAG laser light having a wavelength of 355 nm has a property of transmitting a crystalline material such as sapphire used as an LED substrate. For this reason, even if it irradiates with YAG laser light so that it may permeate | transmit sapphire, it cannot modify | reform to the state which can cleave the irradiated part.
For this reason, conventionally, laser light is condensed inside sapphire and the condensing portion is modified so as to be cleaved (Patent Documents 1 and 2).

Conventionally, by moving the liquid jetted in the liquid column shape along the planned cutting line of the workpiece, by passing the laser light into the liquid jetted liquid and guiding it to the workpiece, A laser processing method is known in which laser light is irradiated along a planned cutting line of a workpiece (Patent Document 3).
In this case, for example, a groove is formed by irradiating a laser beam passing through a workpiece such as glass or a silicon wafer along the planned cutting line, and the workpiece is cut using the groove. Yes.
Japanese Patent No. 3873098 JP 2008-6492 A JP 2007-253213 A

Sapphire used as a substrate for LED usually has a thickness of about 100 μm, and it has been an extremely complicated task to adjust the light condensing point inside such a thin film. In particular, when a femtosecond laser oscillator is used as in Patent Document 2, the apparatus is very expensive.
On the other hand, in the laser processing method using a liquid column disclosed in Patent Document 3, a region to be a product is taken to form a groove on the surface of the workpiece, and the surface accuracy of the groove is good. There was no problem.
By the way, in the laser processing method of Patent Document 3, the laser beam is introduced into the liquid column by the condensing lens, but this condensing lens is used to introduce the laser beam into the liquid column. This is not to focus the laser beam on the workpiece. That is, the laser beam introduced into the liquid column is guided toward the workpiece by the liquid column while being totally reflected at the boundary surface between the liquid column and air due to the difference in refractive index between the liquid column and external air. As a result, the laser beam guided by the liquid column and irradiated onto the workpiece is a luminous flux having a divergence angle because of the function of the liquid column as a waveguide.
Therefore, conventionally, a laser processing method using a liquid column is used to form a focal point inside a crystalline material that transmits laser light, thereby modifying the inside of the crystalline material to a state that can be cleaved. It was never considered to do.
However, according to the present invention, when a laser beam is irradiated to a crystalline material that transmits the laser beam by using a laser processing method using a liquid column, the irradiated portion can be modified to a state that can be cleaved. It was made based on the knowledge that.

That is, the invention of claim 1 includes a laser oscillator that oscillates a laser beam that passes through a crystalline material as a workpiece, irradiates the laser beam along a planned cutting line of the crystalline material, and In the method of cleaving a crystalline material that has been modified so that it can be cleaved,
A processing head that ejects liquid in a liquid column shape toward the crystalline material, a liquid supply unit that supplies high-pressure liquid to the processing head, and a laser beam oscillated from the laser oscillator is introduced into the liquid column. Laser introducing means is provided, and the liquid jetted in the liquid column shape is relatively moved along the planned cutting line of the crystalline material, and the laser beam is passed through the liquid column-shaped jetted liquid and guided to the crystalline material. Then, the irradiated portion is modified so that the irradiated portion can be cut off.
The invention of claim 7 provides a processing table for supporting a crystalline material as a workpiece, a laser oscillator for oscillating a pulsed laser beam that passes through the crystalline material, and the laser beam for the crystalline material. In the crystal material cleaving apparatus comprising a moving means for relatively moving the irradiation position of
A processing head that ejects liquid in a liquid column shape toward the crystalline material, a liquid supply unit that supplies high-pressure liquid to the processing head, and a laser beam oscillated from the laser oscillator is introduced into the liquid column. A laser introducing means;
The laser oscillator is a laser oscillator that oscillates a pulsed laser beam having a pulse width of 10 to 100 ns, a peak power density of 30 to 120 MW / cm ² , and a wavelength of 460 nm or less, and the processing head has a diameter of the liquid column. As a processing head for spraying to a crystalline material with a thickness of 100 μm or less, the crystalline material is modified by the laser beam so that it can be cut along the planned cutting line.

According to the above-described invention of the present application, while the liquid jetted in the liquid column shape is relatively moved along the planned cutting line of the crystalline material, the laser beam is passed through the liquid jetted liquid to the workpiece. By irradiating with guidance, the irradiated portion can be modified to a state that can be cleaved without requiring an operation of focusing on the inside of the crystalline material.
Therefore, since it is not necessary to focus on the inside of a thin crystalline material with high accuracy as in the prior art, there is an effect that workability is greatly improved.

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below with reference to the drawings. FIG. 1 shows a laser processing apparatus 1 and guides a laser beam L to a liquid column W formed by jetting a liquid, thereby forming a crystal as a workpiece. The material 2 can be cleaved into a required shape.
The laser processing apparatus 1 includes a processing table 3 that supports the crystalline material 2, a YAG laser oscillator 4 that oscillates a laser beam L with a Q switch pulse, a liquid supply means 5 that supplies a high-pressure liquid, and a crystalline material And a processing head 6 for injecting a liquid as a liquid column W toward the liquid crystal 2 and guiding a laser beam L to the liquid column W, which are controlled by a control means 7.

The laser processing apparatus 1 includes a reflection mirror 8 that reflects the laser light L toward the processing head 6 and a condenser lens 9 that condenses the laser light L between the laser oscillator 4 and the processing head 6. The laser beam L condensed by the condenser lens 9 passes through the passage in the processing head 6 and is introduced into the liquid column W.
In this embodiment, the reflecting mirror 8 and the condenser lens 9 constitute a laser introducing means 10 for introducing the laser light L oscillated from the laser oscillator 4 into the liquid column W. Then, the laser beam L introduced into the liquid column W is transmitted through the crystalline material 2 while being guided by the inside while being totally reflected by the boundary surface between the liquid column W and the outside air. .

The processing head 6 includes a cylindrical housing 11 having a hollow portion penetrating in the vertical direction, an injection nozzle 12 provided at a lower portion of the hollow portion of the housing 11, and an upper portion of the hollow portion of the housing 11. And a transparent transmission member 13 provided.
The hollow portion of the housing 11 is formed on the optical path of the laser light L condensed by the condenser lens 9, and the injection nozzle 12 and the transmission member 13 are provided on the optical path.
The injection nozzle 12 is fitted in a recess formed in the lower end portion of the housing 11 via a seal ring, and is pressed and held by a fixing member 14 from below the housing 11.

The transmission member 13 is made of transparent glass that transmits the laser light L, is located between the injection nozzle 12 and the condenser lens 9, and maintains a liquid-tight state by interposing a seal ring between the housing 11. It is held in the state. The transmission member 13 is fixed to the housing 11 by a hollow nut member 15.
A liquid passage 16 to which the liquid supply means 5 is connected is formed in a space formed between the jet nozzle 12 and the transmission member 13 so that high-pressure liquid is supplied from the liquid supply means 5. Yes.
An injection hole 12 a for injecting liquid is formed in the center of the injection nozzle 12, and a through-hole 14 a having a larger diameter than the injection hole 12 a of the injection nozzle 12 is formed in the center of the fixing member 14.

For this reason, when a high-pressure liquid is supplied from the liquid supply means 5 to the processing head 6, the liquid flows through the liquid passage 16 and is injected as a liquid column W from the injection hole 12 a of the injection nozzle 12. The liquid column W passes through the through hole 14a and collides with the crystalline material 2.
Further, the laser beam L from the laser oscillator 4 is condensed inside the liquid column W ejected from the ejection hole 12a by the condensing lens 9, whereby the laser beam L is condensed into the liquid column. The crystalline material 2 is irradiated with W guided as a light guide.

Next, the processing table 3 is provided on the X direction moving mechanism 17 and is movable in the X direction on the horizontal plane. The X-direction moving mechanism 17 is provided on the Y-direction moving mechanism 18 and can move in the Y direction orthogonal to the X direction on the horizontal plane. The operation of the X direction moving mechanism 17 and the Y direction moving mechanism 18 is controlled by the control device 7.
Then, when both the moving mechanisms 17 and 18 are moved in the XY direction by the required amount by the control device 7, the crystalline material 2 and the processing head 6 on the processing table 3 are relatively moved in the XY direction. It has become so. In this embodiment, the X-direction moving mechanism 17 and the Y-direction moving mechanism 18 constitute moving means 21 that relatively moves the machining head 6 and the machining table 3 on a horizontal plane.

In this embodiment, the YAG laser oscillator 4 is a semiconductor laser-pumped Nd: YAG laser oscillator with a Q switch, which can oscillate the third harmonic with a wavelength of 355 nm, and change the oscillation conditions such as the pulse frequency. Can be done. The laser oscillator 4 may be Nd: YVO ₄ or Nd: YLF.
Further, as the crystalline material 2, sapphire serving as a substrate for LED is used. The YAG laser beam has a wavelength of 355 nm that is transparent to sapphire, but when sapphire is irradiated with the laser beam L via the liquid column W, a modified portion suitable for cleaving is generated by causing multiphoton absorption. Can be formed. Examples of the crystalline material other than sapphire include gallium nitride and crystalline silicon.
The wavelength of the laser oscillator 4 may be a wavelength transparent to the crystalline material 2, and may be 460 nm or less in the case of sapphire.

Further, the liquid supply means supplies water having a refractive index 1.34 smaller than the refractive index 1.79 of the sapphire at a high pressure, and the injection hole 12a of the injection nozzle 12 has a liquid column W. The high-pressure liquid can be sprayed onto the crystalline material 2 so that the diameter of the liquid crystal becomes 100 μm or less.
According to the experiment, if the diameter of the liquid column W is small, the laser beam L can be concentrated more effectively. If the diameter of the liquid column W is increased, the portion where the laser beam is concentrated spreads and the crystalline material 2 is concentrated. This is because a high output is required to form a modified portion suitable for cleaving.

The cleaving process of the crystalline material 2 by the laser processing apparatus 1 having the above configuration will be described.
First, in a state where the oscillation of the laser beam L from the YAG laser oscillator 4 is stopped and the supply of high-pressure water from the liquid supply means 5 is stopped, the crystalline material 2 as a workpiece is processed on the processing table. 3 is mounted and fixed.
Thereafter, both the moving mechanisms 17 and 18 of the moving means 21 are operated by the control device 7, and the processing table 3 is moved by a required amount in the XY direction on the horizontal plane, and the crystalline material 2 is placed below the processing head 6. The machining start position is positioned.
Thereafter, the control device 7 operates the liquid supply means 5 to supply high-pressure water to the processing head 6, and injects the high-pressure water formed in the liquid column W from the processing head 6 to the processing start position of the crystalline material 2. Let Thereafter, the control device 7 oscillates the laser beam L from the laser oscillator 4, and irradiates the laser beam L oscillated from the laser oscillator 4 from the machining head 6 through the liquid column W to the machining start position of the crystalline material 2. Let

The laser beam L that passes through the liquid column W has a refractive index difference between water having a refractive index of 1.34 and air having a refractive index of 1.0. It is totally reflected by the boundary surface, and is guided toward the crystalline material 2 by the liquid column W without being emitted outside the liquid column W due to the total reflection. At this time, the liquid column W functions as a laser beam waveguide, and the guided laser beam has a spread angle.
When the laser beam L reaches the inner surface of the crystalline material 2, the crystalline material 2 is transparent to the laser beam L having a wavelength of 355 nm, so that the laser beam L enters the crystalline material 2, At this time, since the refractive index 1.79 of sapphire as the crystalline material 2 is larger than the refractive index of water 1.34, the laser light L has a small incident angle (transmission angle) with respect to a large incident angle. To be incident on the crystalline material 2.
The laser beam L incident into the crystalline material 2 caused multiphoton absorption by a part of the laser beam L, and the irradiated portion could be modified to be cleaved.

As described above, when the crystalline material 2 is irradiated with the laser beam L through the liquid column W, the control device 7 causes the processing head 6 and the processing table 3 to pass through both the moving mechanisms 17 and 18 of the moving means 21. And move relative to each other.
The relative movement speed at this time is preferably not more than D * F, where D is the diameter of the liquid column W and F is the pulse repetition frequency of the laser light L. The mass part can be formed continuously in the relative movement direction. However, since the processing speed is too slow at 0.0002 D * F or less, the relative movement speed is preferably in the range of (0.0002 to 1) D · F.
As described above, the relative position of the irradiation position of the laser beam L in the liquid column W can be traced along the planned cutting line inside the crystalline material 2 by sequentially moving along the planned cutting line of the crystalline material 2. A reforming part is formed.
If the modified portion is continuously formed along the planned cutting line, the crystalline material 2 can be easily cut with a weak bending stress in a subsequent process.

Specific experimental examples in the present invention are as follows.
Sapphire 2 thickness: 100 μm
Diameter of liquid column W: 100 μm
Wavelength of laser light L: 355 nm
Pulse width of laser light L: 10 ns
Under the above-mentioned conditions, when irradiation is performed while changing the pulse energy per pulse, a good modified portion can be formed on the back side of sapphire 2 (opposite to the laser light irradiation side) in the range of 25 to 100 μJ. did it. When the peak power density of the laser light is corrected, the range is 30 to 120 MW / cm ² .
When the pulse energy was less than 25 μJ, the modified portion was not formed. On the other hand, when it exceeds 100 μJ, a scribing groove was generated on the surface of sapphire 2. Further, even if the pulse energy is increased, the modified portion can be formed on the surface of the sapphire 2, but this is not desirable because the boundary of the modified portion becomes rough and the accuracy of the fractured surface deteriorates.

From the above experimental example, when the pulse width was changed to 100 ns and irradiation was performed while changing the pulse energy per pulse, a good modified portion could be formed in the range of 25 to 100 μJ.
When the pulse width was shorter than 10 ns, a scribe groove was formed on the surface of sapphire, and conversely, when the pulse width was longer than 100 ns, the modified portion was not formed.
The modified portion is formed on the back side or inside of the crystalline material 2 when viewed in the optical axis direction of the laser beam L, and is formed to extend longer in the thickness direction when the output is increased. I was able to. Further, the formation position of the reforming portion could be changed in the depth direction depending on the diameter of the liquid column W.

Sectional drawing which shows one Example of this invention.

Explanation of symbols

1 Laser processing equipment 2 Workpiece (Sapphire)
DESCRIPTION OF SYMBOLS 3 Processing table 4 Laser oscillator 5 Liquid supply apparatus 6 Processing head 7 Control means 9 Condensing lens 10 Laser introduction means 12 Injection nozzle 12a Injection hole 13 Transmission member 21 Moving means L Laser beam W Liquid column

Claims (7)

A laser oscillator that oscillates a laser beam that passes through a crystalline material as a workpiece is provided, and the laser beam is irradiated along the planned cutting line of the crystalline material, so that the irradiated portion is modified into a cleaving state. In the method for cleaving the crystalline material,
A processing head that ejects liquid in a liquid column shape toward the crystalline material, a liquid supply unit that supplies high-pressure liquid to the processing head, and a laser beam oscillated from the laser oscillator is introduced into the liquid column. Laser introducing means is provided, and the liquid jetted in the liquid column shape is relatively moved along the planned cutting line of the crystalline material, and the laser beam is passed through the liquid column-shaped jetted liquid and guided to the crystalline material. A method for cleaving a crystalline material, wherein the irradiated portion is modified so that the irradiated portion can be cleaved by irradiation.   The method for cleaving a crystalline material according to claim 1, wherein a modified portion is formed on the opposite side or inside of the crystalline material on the side irradiated with laser light.   The method for cleaving a crystalline material according to claim 1 or 2, wherein the liquid is water and the crystalline material is sapphire. The method for cleaving a crystalline material according to any one of claims 1 to 3, wherein the laser beam is a pulse laser beam having a pulse width of 10 to 100 ns and a peak power density of 30 to 120 MW / cm ^2. .   The method for cleaving a crystalline material according to claim 4, wherein the diameter of the liquid column is 100 μm or less.   The relative movement speed between the crystalline material and the irradiation position of the laser beam is in the range of (0.0002 to 1) D · F, where D is the diameter of the liquid column and F is the pulse repetition frequency of the laser beam. The method for cleaving a crystalline material according to claim 5, wherein: A processing table that supports a crystalline material as a workpiece, a laser oscillator that oscillates a pulsed laser beam that passes through the crystalline material, and a movement that moves the irradiation position of the laser light relative to the crystalline material A crystal material cleaving apparatus comprising:
A processing head that ejects liquid in a liquid column shape toward the crystalline material, a liquid supply unit that supplies high-pressure liquid to the processing head, and a laser beam oscillated from the laser oscillator is introduced into the liquid column. A laser introducing means;
The laser oscillator is a laser oscillator that oscillates a pulsed laser beam having a pulse width of 10 to 100 ns, a peak power density of 30 to 120 MW / cm ² , and a wavelength of 460 nm or less, and the processing head has a diameter of the liquid column. An apparatus for cleaving a crystalline material, wherein the crystalline material is modified into a state that can be cleaved along the planned cutting line by the laser beam as a processing head that is injected to the crystalline material at 100 μm or less.

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