KR100843411B1 - Laser beam machining system and method for cutting of substrate using the same - Google Patents

Abstract

A laser machining apparatus is provided to cut the transparent substrate more efficiently by splitting a single beam into multiple beams and irradiating the multiple beams onto a transparent substrate, and a method for cutting a substrate using the laser machining apparatus is provided. A laser machining apparatus comprises: a light source for projecting a laser beam(L); first and second reflection mirrors(101a,101b) disposed to be parallel to each other such that respective reflecting faces of the reflection mirrors face each other; a beam splitter(102) which is disposed between the first and second reflection mirrors such that the beam splitter is parallel to the first and second reflection mirrors, and which splits an incident beam into a transmitting beam and a reflecting beam; and an internal lens(103) disposed between the first and second reflection mirrors and provided to change convergence or divergence of the incident beam, wherein the laser beam is irradiated onto one area of a machining object after splitting the laser beam into a plurality of laser beams with different divergence angles by projecting the laser beam such that the laser beam passes through the beam splitter and the internal lens at least twice by the first and second reflection mirrors.

Description

LASER BEAM MACHINING SYSTEM AND METHOD FOR CUTTING OF SUBSTRATE USING THE SAME}

1 is a schematic view showing a laser processing apparatus according to an embodiment of the present invention.

FIG. 2 illustrates a process of scribing an object to be processed by a laser beam in the embodiment of FIG. 1.

3 shows a state in which a crack is generated by the scribing process according to the present embodiment, and the transparent substrate is cut using a brake bar.

<Description of the symbols for the main parts of the drawings>

101a, 101b: first and second reflecting mirror 102: first and beam splitter

103: internal lens 105: objective lens

110: transparent substrate 120: stage

300: brake bar

The present invention relates to a laser processing apparatus and a method for cutting a transparent substrate, and more particularly, to a laser processing apparatus and a substrate cutting method capable of cutting a transparent substrate more efficiently by dividing a single beam into multiple beams and irradiating the transparent substrate. It is about.

Recently, as the importance of the display industry for displaying various information on the screen increases, research on a flat panel display capable of high resolution and a portable display has been actively conducted.

Such flat panel displays are generally formed in a plurality of matrix forms on a brittle substrate, such as a semiconductor chip such as a large scale integrated circuit, and manufactured by cutting a substrate into each device unit.

In this case, as a method used for cutting brittle substrates such as glass, silicon, ceramics, etc., the substrate is cut by a diamond blade having a thickness of about 50 to 200 µm to rotate the substrate at high speed, and a groove for cutting is formed in the substrate. A scribing method such as a scribing method of forming cracks in the thickness direction of the substrate by forming a groove for cutting on the surface of the substrate by a dicing and a scribing wheel made of diamond having a thickness of about 0.6 to 2 mm Representative.

First, since the dicing uses a very thin blade as compared to scribing, the dicing is suitable for cutting a substrate having a thin film or convex portion on its surface. However, in the case of dicing, frictional heat is generated in the area where the blade is cut and supplied while cooling water is supplied to the area, so that it is never a preferred method for a flat panel display including a metal electrode layer, a metal terminal, and the like. Dicing also has a problem that the cutting time is longer compared to scribing, and the productivity is not good.

On the other hand, scribing has an advantage that the product yield is good and the productivity is excellent because the cutting time is shorter than dicing. However, scribing wheels made of diamonds are expensive and may cause defects in flat panel display devices due to the lamination of particles generated during scribing.

The present invention is to solve the above problems, an object of the present invention is to provide a laser processing apparatus and a substrate cutting method that can cut a transparent substrate more efficiently by dividing a single beam into multiple beams and irradiating the transparent substrate. It is.

In order to achieve the above object, one aspect of the present invention,

A light source that emits a laser beam, first and second reflecting mirrors disposed in parallel so that respective reflecting surfaces face each other, and parallel to the first and second reflecting mirrors between the first and second reflecting mirrors; A beam splitter disposed between the first and second reflecting mirrors and disposed between the first and second reflecting mirrors and arranged to alter the convergence or divergence of the incident beams, wherein the laser beam The laser is incident on the beam splitter and the inner lens by the first and second reflecting mirrors at least twice, divided into a plurality of beams having different divergence angles, and then irradiated to one region of the workpiece. Provide a processing device.

Preferably, the plurality of beams divided from the laser beam are each positioned in a different area of the workpiece, and the focal points are positioned immediately before the same, and an imaginary straight line connecting the focal points is in the thickness direction of the workpiece. It may be straight.

In addition, in terms of improving processing efficiency, the divided plurality of beams may be output in the direction of the object to be processed with the same path to each other.

Meanwhile, the light transmittance of the beam splitter may be 50%, and the distances from the beam splitter to the first and second reflecting mirrors are preferably equal to each other.

In addition, the beam splitter and the inner lens are preferably arranged in parallel with each other.

Preferably, the inner lens may be disposed between the first reflecting mirror and the beam splitter or between the second reflecting mirror and the beam splitter.

As an additional component, the lens shifting device may further include a lens shifting device that adjusts a focus position of the divided plurality of beams by moving the inner lens in an optical axis direction.

The method may further include an objective lens that collects the plurality of divided beams and irradiates the processed object.

On the other hand, the object is preferably made of a transparent material.

Preferably, the method may further include a CCD camera or an image sensor for photographing the processing area of the processing object.

In addition, it is preferable that the laser beam emitted from the light source is a femtosecond laser beam in terms of processing efficiency.

Another aspect of the invention,

Aligning the transparent substrate on a stage and oscillating a laser beam from a light source, dividing the laser beam into a plurality of beams having different divergence angles, and dividing the divided plurality of beams into different regions of the transparent substrate. It provides a transparent substrate cutting method comprising the step of scribing the transparent substrate in the thickness direction by irradiation.

In this case, during the scribing, the method may further include moving the stage in a direction to cut the transparent substrate.

The method may further include cutting the transparent substrate by pressing the crack with a brake bar after forming a crack in the transparent substrate by the scribing.

Hereinafter, embodiments of the present invention will be described with reference to the accompanying drawings. However, embodiments of the present invention may be modified in various other forms, and the scope of the present invention is not limited to the embodiments described below. Embodiments of the present invention are provided to more completely explain the present invention to those skilled in the art. Accordingly, the shape and size of elements in the drawings may be exaggerated for clarity, and the elements denoted by the same reference numerals in the drawings are the same elements.

1 is a schematic view showing a laser processing apparatus according to an embodiment of the present invention.

The laser processing apparatus according to the present embodiment includes a light source that emits a laser beam L, a beam splitter 102, first and second reflecting mirrors 101a and 101b, an internal lens 103, and an objective lens 105. It is comprised.

First, before the laser beam L is emitted, the transparent substrate 110 to be processed is disposed on the movable stage 120. In this case, the transparent substrate 110 is disposed so that the output beam of the laser processing apparatus is directly irradiated on the processing surface of the transparent substrate 110. On the other hand, the present embodiment relates to processing a transparent substrate with a laser beam, but in the present invention can be processed as long as the object to be processed is made of a material that can transmit the laser beam even if it is not transparent.

Subsequently, the laser beam L is emitted from the light source, the laser beam L is incident to the beam splitter 102, is divided into a plurality of beams, and is irradiated onto the transparent substrate 110. do.

The first and second reflecting mirrors 101a, 101b, which reflect the incident beam to provide the reflected beam to the beam splitter 102, are parallel to each other and are disposed such that the respective reflecting surfaces face each other. In addition, the beam splitter 102 and the inner lens 103 are also disposed in parallel with the first and second reflecting mirrors 101a and 101b, even if the beam splitter 102 and the inner lens 103 are not slightly parallel to each other. There is no big problem in irradiating and processing a laser beam.

Hereinafter, with reference to FIG. 1, the principle that the laser beam L is divided and outputted as a plurality of beams different in convergence or divergence degree (hereinafter described by divergence angle) from each other will be described.

First, the laser beam L emitted from the laser light source is incident on the beam splitter 102 at a predetermined incident angle θ. Here, some of the incident beams pass through the beam splitter 102. The transmission beam passes through the internal lens 103 to the second reflection mirror 101b, and the remaining non-transmission beam, that is, the beam reflected by the beam splitter 102, is directed to the first reflection mirror 101a. .

In this case, the light transmittance and the light reflectivity of the beam splitter 102 with respect to the laser beam L may be appropriately adjusted, except that the light transmittance and the light reflectivity in terms of uniformizing the intensity of the plurality of output beams. The ratio of is 1: 1, that is, the light transmittance of the beam splitter 102 is preferably 50%.

On the other hand, the beam directed to the second reflecting mirror 101b via the inner lens 103 is reflected by the second reflecting mirror 101b, and again to the beam splitter 102 via the inner lens 103. Come back. Accordingly, once again, the beam splitter 102 undergoes the transmission and reflection process. That is, a part of the beam reflected by the second reflecting mirror 101b passes through the beam splitter 102 and is directed to the first reflecting mirror 101a, and the other beam, that is, by the beam splitter 102 The reflected beam is returned to the second reflecting mirror 101b again.

Similarly, when the laser beam L is incident, the beam reflected by the beam splitter 22 for the first time also undergoes a process of reflection and transmission.

As described above, the beam reflection and transmission process is repeated, and the first laser beam L may be divided into a plurality of beams and output. That is, one beam is divided into two each time the beam splitter 102 passes through the beam splitter 102, and the divided beam passes through the process of reciprocating between the first and second reflecting mirrors 101a and 101b. The number increases. Accordingly, the laser beam L may be incident by the first and second reflection mirrors 101a and 101b to pass through the beam splitter 102 at least twice and output as a plurality of divided beams.

Meanwhile, as shown in FIG. 1, when the laser beam L is output as a plurality of split beams, the plurality of split beams are irradiated to the transparent substrate 110 with the same path to each other. As such, in the case of having the same path, that is, when the plurality of split beams pass through the objective lens 105 in a superimposed form, the beams may be concentrated in the processing region of the transparent substrate 110. .

In order for the plurality of split beams to have the same paths, the beam splitter 102 is preferably positioned at the center of the first and second reflecting mirrors 101a and 101b. In this case, when the incident angle θ is 45 °, the plurality of split beams have the same path to each other. If the beam splitter 102 is disposed at a position different from this embodiment, the incident angle θ may be adjusted so that the plurality of split beams have the same path to each other.

In the present embodiment, the incident angle θ is the angle at which the laser beam L is incident on the beam splitter 102, that is, the case where the incident beam is directly incident on the beam splitter 22 has been described. It is also conceivable to enter the first reflecting mirror 101a or the second reflecting mirror 101b. In this case, although not shown, if the beam splitter 102 is parallel to the first and second reflecting mirrors 101a and 101b, an incident angle to the first reflecting mirror 101a or the second reflecting mirror 101b. Is equal to the angle incident on the beam splitter 102, and the process of splitting and outputting the beam is as described above.

The splitting process of the laser beam L has been described above, and the following describes a process of varying the degree of convergence or divergence of the divided beams by passing through the internal lens 103 during the splitting process.

The inner lens 103 functions to focus the incident beam, like other lenses in general. In the present embodiment, during the process of splitting the laser beam L as described above, the divided plurality of output beams have different times or paths through the internal lens 103. Therefore, the plurality of output beams have different divergence angles, and thus, when the transparent substrate 110 is irradiated, the focus positions are different from each other. In other words, the plurality of output beams have different irradiation positions irradiated to the transparent substrate 110. Accordingly, by properly adjusting the focal positions of the plurality of output beams, the efficiency of laser processing can be improved.

On the other hand, the internal lens 103 may be any lens that can vary the divergence angle of the plurality of output beams, but considering the distance to the transparent substrate 110 in terms of improving the processing efficiency For example, a lens having a long focal length may be preferable.

Also, in the present embodiment, the internal lens 103 has been described as being disposed between the first reflecting mirror 101a and the beam splitter 102, but is not limited thereto, and the second reflecting mirror 101b Even if arranged between the beam splitters 102, the function does not change.

Referring to FIG. 2, the process of scribing the transparent substrate 110 by the plurality of output beams having different divergence angles will be described.

FIG. 2 illustrates a process of scribing an object to be processed by a laser beam in the embodiment of FIG. 1.

Referring to FIG. 2, the focal points of the plurality of output beams divided from the laser beam L are located in a straight line in the thickness direction of the transparent substrate 110. In this case, the respective focal positions f1, f2, and f3. ) Are different. This is because, as described above, the plurality of output beams converge or diverge with each other, that is, divergence angles are different.

In FIG. 2, a path through which three beams are irradiated onto the transparent substrate 110 is illustrated. That is, as shown in FIG. 2, the three beams illustrated by different lines have different divergence angles incident on the objective lens 105, and accordingly, the focal points positioned on the transparent substrate 110 are different. . In this case, the focal positions f1, f2, and f3 lie on a virtual straight line in the thickness direction of the transparent substrate 110 to be processed. That is, the focal points of three beams having different divergence angles are located on one surface of the transparent substrate 110, on the opposite surface, and on the center of the center.

On the other hand, a plurality of other beams (not shown) are irradiated onto the transparent substrate 110 with the focal point located at another point on the straight line.

In this case, the objective lens 105 functions to focus the plurality of output beams and to irradiate different positions of the transparent substrate 110.

In this embodiment, the case where the irradiation positions of the plurality of output beams are different from each other has been described. However, as the number of split and output beams increases, beams having the same divergence angle may be generated. That is, when the number of output beams is very large, the distance between the positions where the output beams are irradiated on the transparent substrate 110 is gradually reduced, and all the lines in the thickness direction to be processed of the transparent substrate 110 can be irradiated. have.

Although not shown, the laser processing apparatus according to the present embodiment may further include a lens shifting device capable of moving the internal lens 103. The plurality of output beams while moving the inner lens 103 in an optical axis direction, i.e., when the inner lens 103 is parallel to the beam splitter 102, in a direction away from or close to the beam splitter 102; The position irradiated to the transparent substrate 110 can be adjusted. In this case, the lens shifting device may be a movable rail or a stage in which the inner lens 103 is aligned.

As described above, when a plurality of output beams having different divergence angles are irradiated onto the transparent substrate 110, scribing can be easily performed in the thickness direction of the transparent substrate 110. In this case, the transparent substrate 110 may be cut by applying pressure with a brake bar after scribing by irradiation of a plurality of output beams.

3 shows a state in which a crack is generated by the scribing process according to the present embodiment, and the transparent substrate is cut using a brake bar.

Referring to FIG. 3, a crack C having a very large taper angle occurs on the transparent substrate 110 through the scribing process described above. When the pressure is applied to the crack C using the brake bar 300 or the like, the transparent substrate 110 may be easily cut.

As described above, the laser processing apparatus according to the present embodiment cuts the transparent substrate 110 by pressing the brake bar or the like after scribing through a plurality of output beams having different focal positions. The substrate can be cut more efficiently than the crushing step, and the quality of the cut surface is also excellent.

Meanwhile, in the present embodiment, the laser beam L may be a femtosecond laser, in which case, the efficiency in substrate processing can be improved.

As a pulsed laser, a femto second laser having a pulse emission time of 10 ^-15 seconds oscillates at an ultra-short pulse emission time, so the oscillation density of energy is very large. In general, with 1 mJ of light energy and pulse emission times of less than 100 femtoseconds, the energy density of the laser beam is approximately 10 gigawatts, allowing any material to be processed. In addition, when the ultra-short pulsed laser beam is radiated to the workpiece, the incident pulse is generated more than the time that the photons transfer heat to the surrounding constituent lattice while the multi-photon phenomenon occurs in the constituent lattice of the material and thereby the atoms are excited. Since it is short, the heat spread at the time of processing of a workpiece can be minimized. Therefore, it is possible to prevent the deterioration of the processing accuracy due to the heat diffusion during the processing, the problem that the physical and chemical changes of the material and the processing part of the workpiece is partially melted is solved, it is possible to perform a high-precision machining.

However, the processing using the femtosecond laser beam has a critical obstacle to commercialization due to the low repetition rate of the femtosecond laser, the processing time is significantly lower than the conventional nanosecond laser or CO ₂ laser processing. The repetition rate of the nanosecond laser used for processing is several to several tens of MHz, and the titanium sapphire laser which is generally used for femtosecond laser processing is 1 KHz and the femtosecond laser processing speed is reduced by 10 ⁴ times.

Therefore, when the femtosecond laser beam is used in the laser processing apparatus according to the present invention, since the desired number of output beams can be easily adjusted and divided, the laser processing speed can be significantly improved.

Finally, although not shown, the laser processing apparatus according to the present invention may further include a CCD camera or an image sensor for photographing a processing region of the object, in particular, a transparent substrate, and in this case, a display displaying the photographed image. Device may also be included. Accordingly, the focusing position of the laser beam may be more easily adjusted while looking at the processing area.

The present invention is not limited by the above-described embodiment and the accompanying drawings, but is intended to be limited by the appended claims. Accordingly, various forms of substitution, modification, and alteration may be made by those skilled in the art without departing from the technical spirit of the present invention described in the claims, which are also within the scope of the present invention. something to do.

As described above, according to the present invention, it is possible to provide a laser processing apparatus and a substrate cutting method capable of cutting a transparent substrate more efficiently by dividing a single beam into multiple beams and irradiating the transparent substrate.

Claims (16)

A light source for emitting a laser beam; First and second reflecting mirrors disposed in parallel such that respective reflecting surfaces face each other; A beam splitter disposed between the first and second reflecting mirrors in parallel with the first and second reflecting mirrors and splitting the incident beam into a transmission beam and a reflection beam; And An internal lens disposed between the first and second reflecting mirrors and provided to change the convergence or divergence of the incident beam; The laser beam is incident by the first and second reflection mirrors through the beam splitter and the inner lens at least twice, is divided into a plurality of beams having different divergence angles, and then irradiated onto a region of the object to be processed. Laser processing device characterized in that. The method of claim 1, The divided plurality of beams are each focused at different areas of the object, and the focal points are located on the same straight line, and the virtual straight line connecting the foci is a straight line in the thickness direction of the object. Processing equipment. The method of claim 1, And the plurality of divided beams have the same path and are output in the direction of the object to be processed. The method of claim 1, And a light transmittance of the beam splitter is 50%. The method of claim 1, And a distance from the beam splitter to the first and second reflecting mirrors is the same. The method of claim 1, The beam splitter and the internal lens are laser processing apparatus, characterized in that arranged in parallel to each other. The method of claim 1, And the inner lens is disposed between the first reflecting mirror and the beam splitter. The method of claim 1, And the inner lens is disposed between the second reflecting mirror and the beam splitter. The method of claim 1, And a lens shifting device capable of adjusting a focus position of each of the divided plurality of beams by moving the inner lens in an optical axis direction. The method of claim 1, And a objective lens for condensing the plurality of divided beams and irradiating the object to be processed. The method of claim 1, Laser processing apparatus, characterized in that the object is made of a transparent material. The method of claim 1, Laser processing apparatus further comprises a CCD camera or an image sensor for photographing the processing area of the processing object. The method of claim 1, And a laser beam emitted from the light source is a femtosecond laser beam. delete delete delete

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