KR100862522B1 - Laser beam machining system and method for cutting of substrate using the same - Google Patents

Abstract

A laser beam machining system and a method for cutting a substrate using the same are provided to cut a transparent substrate rapidly by collecting a plurality of beams through a first objective lens and scanning the beams on the transparent substrate. Three beams are scanned on a transparent substrate(110). The beams have different divergence angles which are formed at a first objective lens(105). Focus positions(f1,f2,f3) are laid on a visual straight line to a thickness direction to which the substrate is processed. The focus of the three beams is formed at one side, the other side, and the center of the substrate. The first objective lens collects a plurality of output beams and scans the beams to different positions on the transparent substrate. A second laser beam is branched from a laser beam and is scanned to an opposite direction to a first laser beam(L1) to cut the substrate.

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 forming an optical waveguide on an object to be processed by the first laser beam in the embodiment of FIG. 1.

3 is a view showing in more detail the state in which the second laser beam is irradiated to the optical waveguide formed on the transparent substrate in FIG.

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

101a and 101b: first and second reflection mirrors 103: internal lens

104, 102: first and second beam splitter 107: beam path adjusting unit

105,106: first and second objective lenses 110: transparent substrate

120: stage W: optical waveguide

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 for emitting a laser beam, a first beam splitter for dividing the laser beam into first and second laser beams, first and second reflecting mirrors disposed in parallel so that respective reflecting surfaces face each other; Between the first and second reflecting mirrors and between the first and second reflecting mirrors and a second beam splitter arranged to be parallel to the first and second reflecting mirrors and splitting the incident beam into transmitted and reflected beams. An internal lens disposed at and provided to alter the convergence or divergence of the incident beam, wherein the first laser beam is passed through the second beam splitter and the internal lens at least twice by the first and second reflecting mirrors. After being incident and divided into a plurality of beams having different divergence angles, the laser beam is irradiated to one region of the object to be processed, and the second laser beam is irradiated to another region of the object to be processed. It provides.

Preferably, the plurality of beams divided from the first laser beam are each focused at different areas of the workpiece, and the focal points are located on the same straight line, and the virtual straight line connecting the focal points is in the thickness direction of the workpiece. May be a straight line.

Furthermore, it is preferable that an optical waveguide is formed on a virtual straight line in the thickness direction by a plurality of beams divided from the first laser beam, and the second laser beam is irradiated onto the optical waveguide to process an object to be processed.

When forming and processing the optical waveguide as described above, after the optical waveguide is formed, further comprising a beam path adjusting unit for adjusting the path of the second laser beam so that the second laser beam is irradiated to the object to be processed, the beam path The adjusting unit preferably has a structure in which a plurality of reflecting mirrors capable of adjusting a distance between each other are arranged in a space.

The second laser beam is preferably irradiated to the object to be processed in a direction opposite to the first laser beam.

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.

On the other hand, the light transmittance of the second beam splitter may be appropriately adjusted, preferably 50%.

Preferably, the distances from the second beam splitter to the first and second reflection mirrors are the same.

In addition, the second beam splitter and the inner lens may be disposed in parallel with each other.

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

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

The method may further include a first objective lens for condensing the plurality of divided beams and irradiating the object to be processed, and further comprising a second objective lens for condensing the second laser beam and irradiating the object to be processed. It may be.

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 first and second laser beams, and dividing the first laser beam into a plurality of beams having different divergence angles from each other; Dividing, irradiating the plurality of divided beams to different areas of the transparent substrate to form an optical waveguide in a thickness direction on the transparent substrate, and adjusting a path of the second laser beam to control the second laser beam. It provides a transparent substrate cutting method comprising the step of irradiating the optical waveguide.

In this case, the method may further include moving the stage in a direction to cut the transparent substrate during the forming of the optical waveguide and irradiating the second laser beam to the optical waveguide.

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 for emitting a laser beam L, first and second beam splitters 104 and 102, first and second reflecting mirrors 101a and 101b, and an internal lens 103. And the beam path adjusting unit 107 and the first and second objective lenses 105 and 106.

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.

In addition, the stage 120 may move in the direction in which the transparent substrate 110 is to be cut, and thus, the cutting of the substrate may be performed by expanding a processing region linearly formed along the thickness direction.

Thereafter, the laser beam L is emitted from the light source, and the laser beam L is divided into first and second laser beams L1 and L2 by the first beam splitter 104. In this case, the light transmittance of the first beam splitter 104 may be appropriately considered in consideration of the required intensities of the first and second laser beams, and as described below, the first laser beam L1 may be a transparent substrate. Since the optical waveguide is divided into a plurality of beams once again to form an optical waveguide at 110, it is preferable to have a higher light intensity than the second laser beam L2.

The first laser beam L1 is incident on the second beam splitter 102, is divided into a plurality of beams, and is irradiated onto the transparent substrate 110, and the second laser beam L2 is beam path adjusting unit 107. After passing through the transparent substrate 110 is irradiated.

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

Hereinafter, referring to FIG. 1, the principle of outputting a plurality of beams in which the first laser beam L1 is divided and converged or diverged to each other (hereinafter referred to as divergence angle) is output.

First, the first laser beam L1 emitted from the laser light source and split by the first beam splitter 104 is incident on the second beam splitter 102 at a predetermined incident angle θ. Here, some of the incident beams pass through the second 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 second beam splitter 102, is the first reflection mirror 101a. Headed to.

In this case, the light transmittance and the light reflectivity of the second beam splitter 102 with respect to the laser beam L may be appropriately adjusted, except that the light transmittance and The ratio of light reflectance is 1: 1, that is, the light transmittance of the second beam splitter 102 is preferably 50%.

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

Similarly, when the first laser beam L1 is incident, the beam reflected by the second 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 L1 may be divided into a plurality of beams and output. That is, each time the second beam splitter 102 passes through, one beam is divided into two, and the divided beam is divided while going back and forth between the first and second reflecting mirrors 101a and 101b. The number of beams added increases. Accordingly, the first laser beam L1 may be incident by the first and second reflecting mirrors 101a and 101b to pass through the beam splitter 102 at least twice and may be output as a plurality of divided beams. .

Meanwhile, as shown in FIG. 1, when the first laser beam L1 is output as a plurality of split beams, the plurality of split beams are irradiated onto the transparent substrate 110 with the same path. As such, in the case of having the same path, that is, when the plurality of split beams pass through the first objective lens 105 in an overlapping form, the beams may be concentrated in the processing region of the transparent substrate 110. There is this.

In order for the plurality of split beams to have the same paths, the second 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 second 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 exemplary embodiment, the incident angle θ is an angle at which the first laser beam L1 is incident on the second beam splitter 102, that is, a case where the incident angle θ is incident directly on the beam splitter 22 has been described. Also, the case where the first reflection mirror 101a or the second reflection mirror 101b is incident first may be considered. In this case, although not shown, if the second beam splitter 102 is parallel to the first and second reflecting mirrors 101a and 101b, the second beam splitter 102 may be applied to the first reflecting mirror 101a or the second reflecting mirror 101b. The incident angle with respect to the beam splitter 102 is equal to the incident angle, and the process of splitting and outputting the beam is as described above.

The splitting process of the first laser beam L1 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 dividing the first laser beam L1 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 second reflecting mirror 101b and the second beam splitter 102, but the present invention is not limited thereto, and the first reflecting mirror 101a is provided. ) And the second beam splitter 102 do not change their function.

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

FIG. 2 illustrates a process of forming an optical waveguide on an object to be processed by the first laser beam in the embodiment of FIG. 1.

Referring to FIG. 2, the focal points of the plurality of output beams divided from the first laser beam L1 are positioned in a straight line in the thickness direction of the transparent substrate 110, and in this case, the respective focal positions f1 and f2. , 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 shown by different lines have different divergence angles incident on the first objective lens 105, and accordingly, focal points positioned on the transparent substrate 110 are respectively different. This is different. In this case, the focal positions f1, f2, and f3 lie on an imaginary 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 first 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 inner lens 103 is moved in the optical axis direction, that is, when the inner lens 103 is parallel to the second beam splitter 102 while moving away from or near the second beam splitter 102. The position at which the plurality of output beams are irradiated onto the transparent substrate 110 may be adjusted. In this case, the lens shifting device may be a movable rail or a stage coupled to the inner lens 103.

As described above, when the 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. An optical waveguide may be formed at 110. In this case, the transparent substrate 110 may be cut by applying pressure with a brake bar after scribing by irradiating a plurality of output beams, or may be cut by irradiating another laser beam to the optical waveguide.

Referring to the process of cutting the transparent substrate 110 by irradiating another laser beam to the optical waveguide, the second laser beam (L2) divided from the laser beam (L) is the first laser beam to the optical waveguide Irradiated in the opposite direction to (L1) serves to cut the transparent substrate 110. In this case, the second laser beam L2 must reach the transparent substrate 110 later than the first laser beam L1.

The path of the second laser beam L2 is adjusted by the beam path adjusting unit 107, and the beam path adjusting unit 107 is composed of a plurality of reflective mirrors M. Specifically, the second laser beam L2 is provided to the beam path adjusting unit 107 via a reflecting mirror and is reflected by the reflecting mirrors M constituting the beam path adjusting unit 107. Here, the distance d between the reflective mirrors M may be appropriately adjusted, whereby the time for the second laser beam L2 to reach the transparent substrate 110 may be adjusted.

On the other hand, Figure 3 shows in more detail the state in which the second laser beam is irradiated to the optical waveguide formed on the transparent substrate in FIG.

As described above, the second laser beam L2 split from the laser beam L reaches the transparent substrate 110 via the beam path adjusting unit 107.

As shown in FIG. 3, the laser beam L2 is irradiated onto the optical waveguide W formed on the transparent substrate 110 in a direction opposite to the first laser beam L1.

In this case, the second laser beam L2 may be irradiated in a focused form by the second objective lens 106, and the second laser beam L2 may be adjusted by adjusting the position of the second objective lens 106. ) Irradiation position can be appropriately selected.

As such, the second laser beam L2 may serve to irradiate the optical waveguide W formed by the first laser beam L1 to finally cut the transparent substrate 110.

The laser processing apparatus according to the present embodiment cuts the transparent substrate 110 after forming the optical waveguide W through a plurality of output beams having different focal positions, and thus is more efficient than the conventional physical scribing process. The substrate can be cut by this, 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 (19)

A light source for emitting a laser beam; A first beam splitter dividing the laser beam into first and second laser beams; First and second reflecting mirrors disposed in parallel such that respective reflecting surfaces face each other; A second beam splitter disposed between the first and second reflecting mirrors so as to be parallel to 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 first laser beam is incident to the second beam splitter and the internal lens at least twice by the first and second reflection mirrors, and is divided into a plurality of beams having different divergence angles, and then a region of the object to be processed. Will be investigated in And the second laser beam is irradiated to another region of the object to be processed. The method of claim 1, The plurality of beams divided from the first laser beam are each focused at different areas of the workpiece, and the focal points are located on the same straight line, and the virtual straight lines connecting the focal points are straight lines in the thickness direction of the workpiece. Laser processing apparatus, characterized in that. The method of claim 2, An optical waveguide is formed on a virtual straight line in the thickness direction of the object by the plurality of beams divided from the first laser beam, and the second laser beam is irradiated to the optical waveguide. . The method of claim 3, After the optical waveguide is formed further comprises a beam path adjusting unit for adjusting the path of the second laser beam so that the second laser beam is irradiated to the object to be processed, And the beam path adjusting unit has a structure in which a plurality of reflecting mirrors capable of adjusting a distance from each other are arranged in a space. The method of claim 1, And the second laser beam is irradiated to the object to be processed in a direction opposite to the first laser beam. The method of claim 1, And the plurality of beams divided from the first laser beam 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 second beam splitter is 50%. The method of claim 1, And a distance from the second beam splitter to the first and second reflecting mirrors is the same. The method of claim 1, And the second beam splitter and the inner lens are disposed in parallel to each other. The method of claim 1, And the inner lens is disposed between the first reflecting mirror and the second beam splitter. The method of claim 1, And the inner lens is disposed between the second reflecting mirror and the second beam splitter. The method of claim 1, And a lens shifting device capable of adjusting a focus position of each of the plurality of beams divided from the first laser beam by moving the internal lens in an optical axis direction. The method of claim 1, And a first objective lens for collecting the plurality of beams divided from the first laser beam and irradiating the object to be processed. The method of claim 1, And a second objective lens for collecting the second laser beam 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. Aligning the transparent substrate on a stage and oscillating a laser beam from a light source; Dividing the laser beam into first and second laser beams; Dividing the first laser beam into a plurality of beams having different divergence angles from each other; Irradiating the plurality of beams divided from the first laser beam to different regions of the transparent substrate to form an optical waveguide on the transparent substrate in a thickness direction; And Adjusting the path of the second laser beam to irradiate the second laser beam to the optical waveguide; Substrate cutting method comprising a. The method of claim 18, Moving the stage in a direction to cut the transparent substrate during the forming of the optical waveguide and irradiating the second laser beam to the optical waveguide.

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