KR100991720B1 - Beam shaping module for laser processing apparatus - Google Patents

Abstract

PURPOSE: A beam shaping module for a laser processor is provided to process a substrate without decreasing brightness and strength and to prevent process time from becoming increased. CONSTITUTION: A beam shaping module for a laser processor is composed of a cylindrical concave lens, a cylindrical convex lens, and a moving unit(600). The cylindrical concave lens emits a laser beam. The cylindrical concave lens corrects the angle of the emitted laser beam. A spot of the laser beam is formed in an object by the angle correction. The moving unit changes a distance between the c cylindrical concave and convex lenses.

Description

Beam shaping module for laser processing equipment {BEAM SHAPING MODULE FOR LASER PROCESSING APPARATUS}

The present invention relates to a beam shaping module for use in laser processing apparatus.

Laser processing refers to a method of processing an object using a laser as a high-density energy source. Types of lasers used for laser processing are classified into solid lasers, gas lasers, liquid lasers and semiconductor lasers according to the type of oscillation material. Recently, with the development of laser technology, a method of scribing or cutting an object with a laser is used in order to chip separation of an object such as a semiconductor substrate or an LED substrate.

Conventionally, a scribing method using a laser uses a process of irradiating a surface of a substrate with a laser beam to form a scribing line first along a cutting line of the substrate, and then breaking by giving a physical or thermal shock. It was common.

In the conventional method, fine dust is generated during cutting, which adversely affects the device characteristics of the substrate. In addition, in the conventional method, since the cutting area is formed relatively wide, there is a limit in integrating a plurality of stacks on a single wafer at high density.

In addition, the conventional method necessarily requires a separate cutting process after scribing, and in this cutting process, a considerable amount of external force must be applied to the substrate. This resulted in an increase in the number of processes and time, and also a cost increase. In addition, if the scribing is not made precisely, the cutting is performed in an undesired direction or the cutting surface is poor.

In addition, in the process of forming the scribing line on the surface of the substrate, the substrate particles melted by the heat of the laser beam are adhered around the scribing line. The phenomenon occurs that is hard to remove due to coagulation, which may cause uneven smooth surface of the substrate and may break in an unexpected direction when breaking.

In addition, when the laser beam is irradiated to the surface of the substrate, the portion with the highest energy density of the laser beam is present on the surface, so irregular micro cracks on the surface of the substrate due to volume expansion due to amorphous or vaporization on the surface. ). For this reason, there exists a problem that a cut | disconnection cross section becomes rough and the characteristic of an element itself also falls.

On the other hand, as one of the scribing methods using a laser, the process of condensing a laser inside the board | substrate is known. However, in order to process the laser by irradiating the inside of the thin substrate, it is necessary to precisely control the position and shape of the spot formed inside the substrate. In particular, each laser has its own divergence angle, which is different even when using the same type of laser light source. Therefore, the conventional laser beam delivery system is used to form spots suitable for internal processing of the substrate. It was difficult.

On the other hand, sapphire substrate is most commonly used as the LED substrate. However, sapphire substrates are very hard and the process of cutting wafers into chips is costly and time consuming.

Conventionally, a method of cutting by mechanically cutting using a dicing saw having a diamond tip for cutting the sapphire substrate, or by applying heat energy to the substrate using a laser to heat and then cooling to apply a thermal stress Mainly used. In this case, there is a problem in that the state of the cut surface of the sapphire substrate is poor and the brightness is reduced, which has become a more serious problem as the high brightness of the LED device is recently advanced. Although the mechanism of reducing the brightness is not known precisely due to the cutting process, the absorption of light in the amorphous region occurring in the cutting region is considered to be the main cause of the reduction of the brightness.

SUMMARY OF THE INVENTION The present invention has been made to overcome the above-mentioned conventional problems, and an object of the present invention is to suppress the generation of fine dust which adversely affects device characteristics, to prevent the generation of unwanted amorphous regions on the substrate surface, An object processing method and an object processing apparatus that can integrate a plurality of laminates in a high density in the same.

Another object of the present invention is to provide an object processing method and an object processing apparatus, which do not cause an increase in the number of processes and processing time and are advantageous in terms of cost.

Another object of the present invention is to provide an object processing method and an object processing apparatus capable of processing a substrate without degrading the device characteristics of the object, such as strength or light brightness.

It is still another object of the present invention to provide an object processing method and an object processing apparatus for forming the spot shape and size of a laser beam suitable for internal processing of a substrate by correcting the divergence angle inherent in the laser.

It is still another object of the present invention to provide an object processing method and an object processing apparatus for controlling a beam intensity profile or energy density of a laser beam formed inside a substrate by correcting an inherent divergence angle of a laser. To provide.

It is still another object of the present invention to provide an object processing method and an object processing apparatus capable of effectively cutting a substrate in a specific direction by controlling the spot shape and size of the laser beam, the light intensity profile or the energy density of the laser beam. .

It is still another object of the present invention to provide an object processing method and an object processing apparatus in which the state of the cut surface is good and the reduction of the brightness is suppressed.

According to a first aspect of the present invention for achieving the above object of the present invention, an object processing method for self-breaking an object using a laser, comprising: generating a laser beam in a laser light source; Correcting a divergence angle of the generated laser beam; And condensing the calibrated laser beam inside the object to form a spot, wherein the shape or size of the spot is adjusted by the divergence angle correction of the laser beam, and the spot is formed inside the object. The phase change region is formed in the object, and the object processing method characterized in that the self-cutting of the object is performed from the phase change region as a starting point.

According to a second aspect of the present invention for achieving the object of the present invention, an object processing method for self-cutting an object having a laminated portion formed on the surface using a laser, comprising: generating a laser beam in a laser light source; Correcting the divergence angle of the generated laser beam; And condensing the calibrated laser beam inside the object to form a spot, wherein the shape or size of the spot is adjusted by the divergence angle correction of the laser beam, and the spot is formed inside the object. The phase change region is formed in the object, and the object processing method characterized in that the self-cutting of the object is performed from the phase change region as a starting point.

According to a third aspect of the present invention for achieving the object of the present invention, as an object processing method for self-cutting an object using a laser, the laser beam generated by the laser light source is passed through a beam shaping module After correcting the divergence angle, by focusing the corrected laser beam in the interior of the object, there is provided a method for processing an object, characterized in that to form a phase shift region having a stress concentration in the interior of the object.

According to a fourth aspect of the present invention for achieving the object of the present invention, an object processing method for self-cutting an object having a laminated portion formed on the surface by using a laser, the laser beam generated from the laser light source to the beam shaping module After passing through the divergence angle to correct, the corrected laser beam is focused on the inside of the object, thereby providing an object processing method characterized by forming a phase shift region having a stress concentration portion inside the object.

According to a fifth aspect of the present invention for achieving the object of the present invention, an object processing apparatus for self-cutting an object using a laser, comprising: a laser light source for generating a laser beam; A beam shaping module for correcting the divergence angle of the laser beam; A condenser lens for condensing the corrected laser beam inside the object to form a spot; And a control unit connected to and controlling the laser light source, the beam shaping module, and the condenser lens, wherein the shape or size of the spot is adjusted by the divergence angle correction of the laser beam, and the object is controlled by the spot. A phase change region is formed in the inside, and the object processing apparatus is characterized in that self-cutting of the object is performed based on the phase change region.

The present invention suppresses the generation of fine dust that adversely affects the device characteristics, prevents the generation of unwanted amorphous regions on the surface of the substrate, and the object processing method capable of high density integration of a plurality of laminates on one wafer and The object processing apparatus can be provided.

In addition, the present invention can provide an object processing method and an object processing apparatus capable of processing a substrate without degrading the device characteristics of the substrate.

In addition, the present invention can provide an object processing method and an object processing apparatus for forming the spot shape and size of the laser beam suitable for the internal processing of the substrate by correcting the divergence angle inherent in the laser.

In addition, the present invention can provide an object processing method and an object processing apparatus for controlling the light intensity profile or the energy density of the laser beam formed inside the substrate by correcting the inherent divergence angle of the laser.

The present invention can also provide an object processing method and an object processing apparatus capable of effectively cutting a substrate in a specific direction by controlling the spot shape and size of the laser beam, the light intensity profile or the energy density of the laser beam.

In addition, the present invention can provide an object processing method and an object processing apparatus in which the state of the cut surface is good and the reduction of the brightness is suppressed.

1 is a schematic configuration diagram of an object processing apparatus according to an embodiment of the present invention.
FIG. 2 is a cross-sectional view of an optical part of the object processing apparatus disclosed in FIG. 1. FIG.
FIG. 3 is a view for explaining a shape change of a spot according to a distance between a cylindrical concave lens and a cylindrical convex lens in the optical unit of FIG. 2.
4 is a cross-sectional view of an optical unit of an object processing apparatus according to another embodiment of the present invention.
FIG. 5 is a view for explaining a shape change of a spot according to a distance between a spherical concave lens and a first cylindrical convex lens in the optical unit of FIG. 4.
FIG. 6 is a view for explaining a shape change of a spot according to a distance between a spherical concave lens and a second cylindrical convex lens in the optical unit of FIG. 4.
7 is a view for explaining the change in the light intensity profile according to the shape change of the spot.
8 is a schematic block diagram showing a light collecting point position control means of the object processing apparatus according to the embodiment of the present invention.
9 is still another schematic configuration diagram showing a light collecting point position control means of the object processing apparatus according to the embodiment of the present invention.
10 is a plan view schematically showing a wafer as an example of an object according to an embodiment of the present invention.
11 is a plan view illustrating a substrate on which a phase change region is formed.
12 is a horizontal cross-sectional view showing a substrate on which two interphase transition regions are formed.
13 is a vertical cross-sectional view showing a substrate on which a phase change region is formed.
14 is a view for explaining the influence of the divergence angle of the laser beam when passing through the lens.
15 is a diagram for explaining a stress concentration phenomenon due to the shape of the phase change region.
16 is a diagram for explaining the relationship between the shape of the spot and the scribing direction.
17 is a view showing a phase change region formed by a laser beam spot.
18 is an actual photograph for comparing a substrate on which self-cutting occurred and a substrate on which self-cutting occurred.
19 is a cross-sectional view of the laminate according to an embodiment of the present invention.

Hereinafter, an embodiment of the present invention will be described with reference to the accompanying drawings.

The following examples of the present invention are not intended to limit or limit the scope of the present invention, but are intended to embody the present invention. As those skilled in the art would realize, the described embodiments may be modified in various different ways, all without departing from the spirit or scope of the present invention. In the drawings, parts irrelevant to the description are omitted in order to clearly describe the present invention, and like reference numerals designate like parts throughout the specification.

Throughout the specification, when a part is "connected" to another part, this includes not only "directly connected" but also "electrically connected" with another element in between. . In addition, when a part is said to "include" a certain component, which means that it may further include other components, except to exclude other components unless otherwise stated.

In addition, in the present invention, "wafer" refers to the state of the substrate before cutting, and "LED chip" or "chip" refers to the state before the package process after cutting the wafer, and "LED package" Means elementized through a package process. In addition, in this invention, the "surface" of a wafer or board | substrate means the upper surface of the board | substrate in which a laminated part is formed, and the "back surface" of a wafer or board | substrate means the lower surface of the board | substrate which is the opposite side to the said surface.

1 is a schematic configuration diagram of an object processing apparatus according to an embodiment of the present invention, and FIG. 2 is a cross-sectional view of an optical part of the object processing apparatus disclosed in FIG. 1.

In one embodiment of the present invention, the object processing apparatus 1 is a mounting table 100 for loading the object 200, the laser light source 300 for generating a laser beam, passing the generated laser beam and the characteristics of the beam and It includes an optical unit 400 for adjusting the path, the control unit 500 for controlling each component, the moving unit 600 and the focusing distance adjusting unit 700.

The object 200 may include a wafer 210 and a stack 220 formed on a surface of the wafer 210 (see FIG. 1). The object 200 may be a semiconductor substrate or an LED substrate, but is not limited thereto. For example, the substrate may be a silicon wafer, a compound semiconductor wafer, a ceramic semiconductor substrate, a sapphire substrate, a metal substrate, a glass substrate, or the like. In addition, the LED substrate may be, but is not limited to, a sapphire single crystal substrate, a ZnO single crystal substrate, a GaN single crystal substrate, and a SiC single crystal substrate. As shown in FIG. 1, the object 200 is maintained in a state in which the lamination part 220 faces downward, that is, a state in which a laser beam is incident through the rear surface of the object 200. However, the object 200 may be maintained on the mounting table 100 in a state in which the lamination part 220 faces upward, that is, the laser beam is incident through the surface of the object 200.

The object 200 includes a wafer 210 and a stack 220 formed on the surface of the wafer 210. The stacking unit 22 may include at least one of an N-GaN layer, a P-GaN layer, an InGaN layer, a P-electrode layer, and an N-electrode layer.

When manufacturing an LED chip, a plurality of nitride layers for forming a functional element are stacked on the surface of an object 200 such as a sapphire substrate. The nitride layer may be formed by epitaxial growth using, for example, a metal organic chemical vapor deposition (MOCVD) method.

In FIG. 19A, the N-GaN layer 221, the InGaN layer 222, and the P-GaN layer 223 are sequentially stacked on the surface of the wafer 210. After etching the stacked substrate 200, the P-electrode layer 224 and the N-electrode layer 225, which are lead portions connected to an external power source, are disposed on the P-GaN layer 223 and the N-GaN layer 221. To form each. At this time, the stacked portion 220 in which the N-GaN layer 221, the InGaN layer 222, the P-GaN layer 223, the P-electrode layer 224, and the N-electrode layer 225 operate as a functional element is used. It constitutes (refer FIG. 19 (b)).

After the stack 220 is formed on the surface of the wafer 210 as described above, an LED chip can be obtained by cutting the substrate 200 along the cut line L shown in FIG. 19B. . The line to be cut L may be partitioned by avoiding the functional elements on the stack 220.

In the above embodiment, the MOCVD method is described as an example of the method of forming the nitride layer, but the present invention is not limited to this method, and other methods well known as the method of forming the nitride layer may be used.

The mounting table 100 may load the object 200 on the upper portion, and may process the object 200 on the upper surface through a rising, lowering or moving forward, backward, and rotation.

The laser light source 300 generates a laser beam used for the processing of the object 200, and the generated laser beam is lasered through a series of devices not shown along the optical axis of the laser light source 300. The light is incident on the cylindrical concave lens 411 of the optical unit 400 through a process of expanding, reducing or outputting the beam size, adjusting the polarization direction, and the like. In this case, the optical axis of the laser light source 300 and the optical axis of the optical unit 400 are arranged to coincide with each other.

The laser light source 300 may be a solid state laser, a gas laser or a liquid laser, and preferably may have a Gaussian beam profile. The laser light source 300 is CO ₂ The laser light source of any one of a laser, an excimer laser, and a DPSS laser may be sufficient.

The laser beam may be a pulse type laser beam, in particular an ultra short pulsed laser beam. Here, the ultra short pulse laser is a nanosecond, pico second, or femto second class laser, and can process thin substrates with high precision. It is advantageous to form spots inside.

The optical unit 400 passes through the laser beam and controls the characteristics and path of the laser beam. The optical unit 400 may include a beam shaping module 410 and a condenser lens 430.

The beam shaping module 410 corrects the divergence angle of the laser beam, and includes a cylindrical concave lens 411 and a cylindrical convex lens 412 that are movable as shown in FIG. 2.

The cylindrical concave lens 411 is positioned above the optical unit 400 and emits a laser beam generated from the laser light source 300. Since the laser beam has a single wavelength and collimation compared to the normal light beam, the laser beam does not spread during propagation and proceeds parallel to the optical axis. However, since the laser beam also has wave characteristics, it is affected by diffraction and thus has a divergence angle. For example, in the case of gas lasers (CO ₂ laser, He-Ne laser, etc.), it is common that the divergence angle does not exceed 1 mrad (0.05 °).

In the case of spherical concave lenses, both orthogonal X- and Y-axis components of the laser beam are emitted. However, in the case of the cylindrical concave lens 411, only one direction component of the orthogonal X-axis or Y-axis is emitted. For example, as shown in FIG. 3, the cylindrical concave lens 411 may emit only the X-axis component of the laser beam.

The laser beam emitted through the cylindrical concave lens 411 passes through the cylindrical convex lens 412, thereby correcting the divergence angle of the laser beam to a desired angle.

That is, when the cylindrical concave lens 411 and the cylindrical convex lens 412 are used, the divergence angle correction for one direction component (for example, the X-axis component) is performed, which causes any one axis in the shape of the spot. Only the size of the direction (for example, the X-axis direction) changes. For example, in the scribing of the object, if the long axis of the spot is arranged along the scribing direction, that is, the line to be cut, the divergence angle correction may be unnecessary in the long axis direction of the spot. In other words, the desired effect can be achieved by reducing the size (shortening of the spot, or the width of the spot) in a direction perpendicular to the cutting line, and the size of the direction along the cutting line (the long axis, or spot). Length) is rather disadvantageously reduced, so that the cylindrical concave lens 411 and the cylindrical convex lens 412 are cylindrical lenses arranged in the same direction, so that divergence angle correction can be performed in only one direction. .

In addition, the divergence angle of the laser beam may be corrected by adjusting the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412, and the cylindrical concave lens 411 using the moving part 600 which will be described later. Or move the position of the cylindrical convex lens 412.

The beam shaping module 410 may further include a beam stopper 420. The beam stopper 420 prevents a portion of the laser beam from being transmitted. For example, a slit or an opening is formed at a central portion thereof to transmit the central region of the laser beam and block the outer region. The outer region of the laser beam with the Gaussian beam profile may not have sufficient intensity and may have an undesirable effect on the stack 220 of the object 200.

The condenser lens 430 collects the corrected laser beam inside the object 200 to form a spot P. The spot shift region T is formed inside the object 200 by the formed spot P. As described above, at least one axial size of the spot P may be changed by the divergence angle correction of the laser beam.

The controller 500 performs various processes related to the laser light source 300, and simultaneously controls the moving unit 600 to adjust the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412. It is possible to correct the divergence angle of, and also, by controlling the light collecting distance adjusting unit 700 to be described later, the distance between the light collecting lens 430 and the spot P of the optical unit 400, that is, the inside of the object 200 The depth of the spot P can be adjusted.

In this case, the controller 500 may control the condensing distance adjusting unit 700 such that a plurality of spots P are formed in the vertical direction in the interior of the object 200. In addition, the controller 500 may control the condensing distance adjusting unit 700 such that a plurality of spots P are formed in the horizontal direction in the inside of the object 200.

The moving unit 600 adjusts the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412 of the optical unit 400 to adjust the divergence angle of the laser beam emitted from the cylindrical concave lens 411. Precise control

Hereinafter, the operation of the optical unit 400 will be described in more detail with reference to FIG. 3. 3 is a view for explaining the shape change of the spot according to the distance between the cylindrical concave lens and the cylindrical convex lens in the optical unit shown in FIG.

The laser beam generated from the laser light source 300 is incident on the cylindrical concave lens 411, and the divergent angle of the laser beam emitted by the cylindrical concave lens 411 is corrected by the cylindrical convex lens 412. . However, when the laser beam generated from the laser light source 300 is perfectly parallel light, the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412 is d _f1 and the focal length of the cylindrical concave lens 411 is When f _c1 and the focal length of the cylindrical convex lens 412 is f _v1 , the size of the spot of the laser beam formed inside the object is minimized when the following conditions are satisfied.

…(수식1)

… (Formula 1)

However, the actual laser beam has a divergence angle of a predetermined size, whereby the point where the spot size of the laser beam is minimized is changed as follows.

…(수식2)

… (Formula 2)

Here, α is an increase component of the focal length of the cylindrical concave lens 411 lengthened by the divergence angle of the laser beam, β is an increase component of the focal length of the cylindrical convex lens 412 lengthened by the divergence angle of the laser beam. to be.

A process of changing the above formula will be described with reference to FIG. 14. First, when assuming a single lens, and assumed that the laser beam is a perfect parallel light, the focal length of the lens (C _c) in the optical axis line of the laser beam passing through the lens (C _c) is a lens _{(C c)} ( Pass the position corresponding to f) (see light path B in Fig. 14). However, when the emitted light diverging angle θ of the laser beam lens (C _c) to pass a laser beam is farther point than the lens (C _c) focal length (f) of the optical axis line of the lens (C _c) to Pass (S ₁ ) (see light path B ₁ of FIG. 14). Here, the increasing component of the focal length, that is, the distance between S ₁ and f becomes a function of θ.

Therefore, as shown in FIG. 3, when the beam shaping module is configured with a pair of cylindrical concave lenses 411 and cylindrical convex lenses 412, Equation 2 may be expressed as follows.

…(수식3)

… (Formula 3)

와

는 각각 레이저 빔의 발산각에 의해 길어진 실린더형 오목렌즈(411)의 초점거리의 증가성분과, 실린더형 볼록렌즈(412)의 초점거리의 증가성분이며, 이들은 각각 레이저 빔의 발산각의 함수가 된다. 따라서, 각 레이저의 발산각에 따라 실린더형 오목렌즈(411)와 실린더형 볼록렌즈(412)의 위치를 적절히 조절함으로써 발산각을 교정할 수 있다.here,

Wow

Are components of increasing the focal length of the cylindrical concave lens 411 lengthened by the divergence angle of the laser beam and components of increasing the focal length of the cylindrical convex lens 412, respectively. do. Therefore, the divergence angle can be corrected by appropriately adjusting the positions of the cylindrical concave lens 411 and the cylindrical convex lens 412 according to the divergence angle of each laser.

On the other hand, the size of the spot of the laser beam formed at the focusing point is expressed as follows.

…(수식4)

… (Equation 4)

Here, M ² is a beam quality factor and is expressed as a function of divergence angle as follows.

…(수식5)

… (Formula 5)

In Equations 4 and 5, f is the focal length of the condenser lens, and D is the diameter of the laser beam incident on the condenser lens. As can be seen from the above formula, 5 M ² is proportional to the angle (θ) the divergence of the laser beam and, as can be seen from the above Equation 4, since the size d of the spot is proportional to M ^2, spots of the end laser beam It can be seen that the magnitude d is proportional to the divergence angle θ of the laser beam. Therefore, when the divergence angle of the laser beam is given a predetermined value, the spot size can be controlled by correcting the divergence angle.

On the basis of the above theory, with reference to FIG. 3 again, the process of adjusting the shape of the spot in the beam shaping module composed of the cylindrical concave lens and the cylindrical convex lens will be described.

First, when the cylindrical convex lens 412 moves in the direction of the arrow as shown in FIG. 3 (a), the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412 satisfies Equation 3 above. Assume we move away from _f1 . In this case, the width of the spot of the laser beam focused by the condenser lens 430 becomes large.

When the cylindrical convex lens 412, as shown in 3 (b) is also contrary to move in the direction of the arrow, d` <sub>f1</sub> to the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412 satisfies the formula 3 Assume that you are close to. In this case, the width of the spot of the laser beam focused by the condenser lens 430 becomes small. Ideally, if the distance between the cylindrical concave lens 411 and the cylindrical convex lens 412 is d` _f1 satisfying the above Equation 3, the width of the spot of the focused laser beam can be minimum.

By adjusting the positions of the cylindrical concave lens 411 and the cylindrical convex lens 412 in this way, the shape of the spot, that is, the width of the spot can be controlled in the interior of the object 200. In general, the shape of the spot is expressed as a function of the size, the divergence angle, and the wavelength of the incident beam. As described above, it is possible to form a spot having a desired shape and size only by correcting the divergence angle, and in particular, an object It is very useful when condensing a laser beam inside the.

When using the non-spherical cylindrical concave lens 411 as described above, the laser beam diverges only in one direction component of the X-axis and Y-axis of the laser beam. For example, as shown in FIG. The axial component passes through the cylindrical concave lens 411 without any change. In other words, the Y-axis component of the laser beam is not affected by the cylindrical concave lens 411 at all.

Referring to the light intensity graph of FIG. 7, the spot size decreases as the width of the spot is narrowed from d1 to d2, while the overall light intensity is preserved, so that the light intensity per unit area is rather increased.

In this way, by adjusting the positions of the cylindrical concave lens 411 and the cylindrical convex lens 412 according to the divergence angle of the laser beam, the spot can be formed into an elliptical shape, or more nearly a linear shape. When the major axis of the elliptical or linear spot is in the scribing direction of the object 200, that is, the direction of the cutting line, the processing speed is significantly improved, and the object is merely irradiated with the laser beam inside the object 200. It is possible to induce self-cutting of (200). Details thereof will be described later.

Next, the structure of the optical unit of the object processing apparatus according to another embodiment of the present invention will be described with reference to FIG. 4.

The beam shaping module 410 of the optical unit 400 according to this embodiment includes a spherical concave lens 413, a first cylindrical convex lens 414, and a first movable convex lens 414, as shown in FIG. 4. And a two-cylindrical convex lens 415.

The spherical concave lens 413 is positioned above the optical unit 400 and emits a laser beam generated from the laser light source 300. The spherical concave lens 413 is distinguished from the cylindrical concave lens 411 described above in that the spherical concave lens 413 can emit a laser beam with respect to both orthogonal X and Y axis components. In this way, since the laser beam is divergent on both the X and Y axes, two cylindrical convex lenses capable of correcting the divergence angle on the X and Y axis components in order to correct the divergent angle of the divergent laser beam Will be needed.

The laser beam emitted through the spherical concave lens 413 in turn passes through the first cylindrical convex lens 414 and the second cylindrical convex lens 415. The positions of the spherical concave lens 413, the first cylindrical convex lens 414, and the second cylindrical convex lens 415 may be changed by the moving unit 600 according to a control command of the controller 500. As a result, the shape or size of the spot formed inside the object is changed. This will be described in detail with reference to FIGS. 5 and 6.

FIG. 5 is a view for explaining a shape change of a spot according to a distance between a spherical concave lens and a first cylindrical convex lens in the optical part disclosed in FIG. 4, and FIG. 6 is a spherical concave lens in the optical part disclosed in FIG. 4. And a shape change of the spot according to the distance between the second cylindrical convex lens.

First, the laser beam generated from the laser light source 300 is incident on the spherical concave lens 413, and the X-axis direction component of the laser beam emitted by the spherical concave lens 413 is the first cylindrical convex lens 414. The divergence angle is corrected by At this time, the distance between the spherical concave lens 413 and the first cylindrical convex lens 414 is the focal length of the spherical concave lens 413 and the focal length of the first cylindrical convex lens 414 and the laser beam. When the value of the increase in the focal length according to the divergence angle is close to the sum value, the width of the spot of the laser beam focused by the condenser lens 430 becomes small (see Fig. 5 (a)). On the contrary, the distance between the spherical concave lens 413 and the first cylindrical convex lens 414 is the focal length of the spherical concave lens 413 and the focal length of the first cylindrical convex lens 414 and the divergence angle of the laser beam. In the case where the increase component of the focal length increases from the sum value, the width of the spot of the laser beam focused by the condenser lens 430 becomes large (see FIG. 5 (b)). As described above, only the divergence angle correction for the X-axis component of the laser beam has been described, and the description thereof will be omitted since it is the same as described with reference to FIG. 3.

However, since the spherical concave lens 413 also diverges the Y-axis component of the laser beam differently from the cylindrical concave lens 411, a second cylindrical convex lens 415 is additionally required.

As shown in FIG. 6, the Y-axis component of the laser beam emitted by the spherical concave lens 413 passes through the first cylindrical convex lens 414 as it is and is diverged by the second cylindrical convex lens 415. The angle is corrected. That is, the first cylindrical convex lens 414 can be treated as if the Y-axis component of the laser beam does not exist. Therefore, the distance between the spherical concave lens 413 and the second cylindrical convex lens 415 is the focal length of the spherical concave lens 413 and the focal length of the second cylindrical convex lens 415 and the divergence of the laser beam. In the case of moving away from the sum of the increase components of the focal length according to the angle, the length of the spot of the laser beam collected by the condenser lens 430 becomes large (see FIG. 6 (a)). On the contrary, the distance between the spherical concave lens 413 and the second cylindrical convex lens 415 is the focal length of the spherical concave lens 413 and the focal length of the second cylindrical convex lens 415 and the divergence angle of the laser beam. In the case where the increase component of the focal length is closer to the sum value, the length of the spot of the laser beam focused by the condenser lens 430 becomes small (see Fig. 6 (b)).

Here, the "width" of the spot indicates the size of the spot in the X-axis direction, that is, the size of the spot in the vertical direction of the object 200 shown in FIGS. 3, 5, and 6, and the "length" of the spot indicates the Y-axis direction of the spot. The size, that is, the size of the spot in the left and right directions in the object 200 shown in FIGS. 3, 5, and 6 is shown.

When the width of the spot is narrow and the length is long, the short axis of the spot is formed in the X-axis direction, and the long axis of the spot is formed in the Y-axis direction (see FIGS. 3 (b) and 5 (a)). When the long axis direction of the spot coincides with the scribing direction, the machining process can be made more efficiently and quickly, and the self-cutting of the object 200 can be induced. This will be described with reference to FIGS. 15 to 19.

15 is a view for explaining a stress concentration phenomenon due to the shape of the phase transition region, FIG. 16 is a view for explaining the relationship between the shape of the spot and the scribing direction, Figure 17 is a phase change formed by the laser beam spot 18 is an actual photograph for comparing a substrate on which self-cutting occurred and a substrate on which the self-cutting occurred.

Fig. 15A shows a case where the spot is formed in a circular shape by not correcting the divergence angle of the laser beam. In this case, looking at the cross section (XZ plane) which cut | disconnected the phase change area | region T perpendicular | vertical to the scribing direction (Y-axis direction) of an object, it will become a substantially round shape. That is, the size of the Z-axis direction and the size of the X-axis direction of the phase shift area are the same.

On the other hand, Fig. 15 (b) shows a case where the spot is formed in an elliptical shape by correcting the divergence angle of the laser beam. In this case, looking at the cross section (XZ plane) which cut | disconnected the phase change area | region T perpendicular | vertical to the scribing direction (Y-axis direction) of an object, it becomes an oval perpendicular to a scribing direction. That is, as shown in the figure, the size of the X-axis direction of the phase change region T in the cross section is small and the size of the Z-axis direction is large. When the shape of the phase change region T is three-dimensionally shown in FIG. 17, it can be seen that both the vertical cross section C1 and the horizontal cross section C2 are elliptical.

On the other hand, in Figure 15, looking at the radius of curvature at the vertical end point of the upper transition region (T), the radius of curvature (R2) of the elliptical spot is smaller than the radius of curvature (R1) of the circular spot Able to know.

In general, the degree of stress generated at a specific point in the phase transition region (T) is represented by the stress concentration factor (S) as follows.

…(수식6)

… (Equation 6)

Here, D is the vertical size of the phase change region T, R is the radius of curvature of the point.

In the case of a circular spot, the stress concentration coefficient at the vertical end point of the phase change area T is S1. In the case of an elliptical spot, the stress concentration coefficient at the vertical end point of the phase change area T is S2. In the case of a circular spot, the vertical size (D1) of the phase change area (T) and the elliptical spot in the vertical direction (D2) of the phase change area (T) are similar to each other, and the radius of curvature is R1> R2. <S2 becomes. That is, in the case of an elliptical spot, it can be seen that the stress is concentrated at the vertical end point of the phase change region T as compared to the circular spot.

In the case of the elliptical spot, cracks can be concentrated at the end points in the longitudinal direction of the elliptical spot due to the concentration of such stress (see FIG. 16 (b)). In other words, in the case of an elliptical spot, a stress concentration part is formed in which the stress is concentrated in the phase change region T as compared with other points. The stress concentration part is formed at the front end or the rear end portion of the object in the phase transition region T. As shown in FIG. The radius of curvature of the phase transition region T is minimized at the stress concentration portion, and thus the crack generation at the stress concentration portion is more active than at other points.

However, in the case of the circular spot, there is no part where stress is particularly concentrated, so that no crack is formed, or even if cracks are formed, they are formed randomly without any particular direction (see Fig. 16 (a)). As described above, in the case of the circular spot, the formation of the cracks cannot be controlled, so that self-cutting is not performed, or even if the cracks are formed, they may be formed in an undesired direction, thereby causing a problem in that the direction of the cutting surface becomes poor.

In the case of an elliptical spot, when the optical unit 400 and the object 200 are arranged such that the long axis of the spot coincides with the cutting line L1 of the object, the spot is formed long in the direction along the cutting line L1. As a result, stress is concentrated in the phase change region formed at both ends of the spot located in the cut line L1, and cracks are formed in the direction along the cut line L1. Therefore, the space | interval of a spot can be enlarged and a processing speed improves remarkably. When such a crack reaches the surface or the back of the object, the object may be self-cut. In this case, by simply irradiating the laser beam inside the object 200, the wafer can be separated into chips without a separate cutting process, thereby reducing the number of processes, reducing process time, and reducing costs. .

As such, after the divergence angle of the laser beam is corrected, the corrected laser beam is focused on the inside of the object to form a spot, thereby inducing cracks in the scribing direction (the long axis direction of the elliptic or linear spot). .

On the other hand, when the object is thick, it is also possible to form a plurality of spots in the vertical direction (thickness direction) of the object. In this case, in the case of a circular spot, as described above, cracks (microcracks) are formed at each spot at random, so that cracks formed at any one spot meet with cracks formed at adjacent spots, thereby propagating the cracks. Is amplified. This directional long crack doubles the adverse effect of randomly forming cracks compared to the case of a single spot (one spot in the thickness direction of the object).

However, in the case of an elliptical spot, cracks formed at any one spot proceed along a scribing direction, that is, a direction in which a cut plane is formed, and since such spots and cracks formed therein are formed at a plurality of points in the thickness direction of the object, The effect of cleavage is amplified.

As such, when the self-cutting is performed on the object, the object can be separated or cut with only a small external force, and ideally, the object can be separated without the application of an external force. In fact, in the case where a phase change area due to a circular spot is formed inside the object (if self-cutting is not performed), the cutting is almost equivalent to forming a cutting line by irradiating a laser beam to the surface or the back of the object. External force F1 is required, but if an elliptical spot is formed inside the object to allow self-cutting, cutting is possible even with a small external force F2 of tens or less as compared with the circular spot.

Particularly, in the case of the circular spot, since the cutting external force F1 is equally applied to the crack formed without special directionality, crack propagation in an undesired direction may be amplified and the direction of the cutting surface may be poor. However, when the elliptical spot is formed inside the object by the divergent angle correction of the laser beam, the crack direction can be guided in the cutting direction, and even if there are cracks formed in a direction other than the cutting direction, the crack is applied to the crack. Since the external force F2 is very small, there is almost no problem that crack propagation is amplified in a direction other than the cut surface and the cut surface is poor.

18 is a photograph showing a laser beam irradiated to a real device having a laminated portion formed on the surface of the object, and photographed from the back side where the laser beam is irradiated before the cutting process after scribing the object (XY plane) to be. FIG. 18A shows a case where a circular spot is formed without performing a divergence angle correction of the laser beam, and FIG. 18B shows a case where an elliptical spot is formed by performing a divergence angle correction of the laser beam. In FIG. 18B, a clean self-cutting line (line formed left and right in the center of the drawing) formed in the direction in which the scribing proceeds (the Y-axis direction) can be seen. In contrast, in Fig. 18A, the self-cutting line in the direction in which the scribing proceeds cannot be seen. In other words, the cutting is performed by giving a physical or thermal impact to the object through a separate subsequent process.

In the present specification, "self-cutting" refers to a case in which a crack generated in a phase change region formed inside an object is propagated and reaches the surface or the back of the object, thereby completely cutting the object, as well as the crack on the surface or the back of the object. It should be understood that even if not reached, cracks propagate to a degree substantially close to the surface or back side of the object, or if some of the cracks reach the surface or back side of the object and others do not.

Although not shown, the laser beam may be polarized in a specific direction. When the polarization direction of the laser beam coincides with the scribing direction, the cutting surface of the object is formed cleanly, and the cutting width becomes small. Therefore, the cutting quality is improved, and a larger number of chips can be obtained with the same size wafer. On the other hand, when the polarization direction of the laser beam is orthogonal to the scribing direction, the cutting surface of the object becomes rough and the cutting width becomes large.

The object processing apparatus 1 according to the embodiments of the present invention as described above may further include a condensing distance adjusting unit 700 for changing the relative position of the object 200 with respect to the condensing lens 430. . The condensing distance adjusting unit 700 may adjust the depth of the condensing point, that is, the spot P, inside the object 200.

In the present invention, by generating the spot (P) of the laser beam on the inside of the object 200 without generating on the surface of the object 200, it is possible to generate the phase change region (T) only inside the object 200, Therefore, the laser beam is not absorbed and melted on the surface of the object 200. Accordingly, irregular irregularities do not occur on the surface of the object 200, so that the cracking in the unexpected direction is reduced when breaking, and the strength and characteristics of the object 200 are reduced due to the occurrence of irregular microcracks on the surface of the object 200. Does not happen.

In addition, since the phase change region T is formed in the interior of the object 200 instead of the surface of the object 200, the fine dust generated during the processing of the object 200 is significantly reduced.

A method of adjusting the depth of the spot P formed inside the object 200 will be described with reference to FIGS. 8 and 9.

If the phase change area | region T is formed in the position of the object 200 closer to the surface side than the back surface side, the cutting precision in the surface side can be improved. However, when the thickness of the object 200 is thin, there is a possibility that the phase change region T formed around the spot P is formed to the surface of the object 200 and exposed to the outside. Therefore, it is necessary to precisely adjust the depth of the spot P.

As a method for adjusting the depth of the spot P, it may be adjusted by changing the relative position of the object 200 with respect to the condenser lens 430. The distance between the condenser lens 430 and the surface of the object 200 is measured by the condenser point detecting means, which is not shown, and the control unit 500 controls the condensing distance adjusting unit 700 using this information. The optical unit 400 is moved up and down so that P is positioned at a desired depth (see FIG. 8). In this case, as an example of the condensing distance adjusting unit 700, an actuator using a piezo element or the like may be used. Piezo actuators are a type of actuator using piezoelectric elements that are used to make movements of several nano resolutions.

As another method, instead of moving the optical unit 400 up and down, a condensing distance adjusting unit 700 is installed below the mounting table 100 on which the object 200 is loaded, and a condensing point position detecting unit (not shown) is provided. The mounting table 100 may be moved up and down by using the distance information between the condenser lens 430 and the surface of the object 200 measured through (see FIG. 9).

As described above, the object processing system is configured to irradiate a laser beam to the inside of the object 200 to form a phase change region T in the inside of the object 200. The laser beam generated by the laser light source 300 may include an optical unit ( By passing through 400, it is possible to implement an object processing system for changing the shape or size of the spot (P) formed in the inside of the object 200.

In addition, the distance between each component in the optical unit may be changed such that at least one uniaxial size of the spot P is changed. At this time, the long axis of the spot (P) is formed substantially along the line (L) to be cut of the object (200).

Thus, in one embodiment of the present invention, the object processing apparatus 1 for self-cutting the object 200 using a laser, the laser light source 300 for generating a laser beam, the divergence angle of the generated laser beam A beam shaping module 410 for correcting the condensation, a condenser lens 430 for condensing the corrected laser beam inside the object 200 to form a spot, and these laser light sources 300, the beam shaping module 410, and the The control unit 500 may be connected to the condenser lens 430 and control them. In addition, the shape or size of the spot is adjusted by the divergence angle correction of the laser beam, a phase shift region is formed in the interior of the object 200 by the spot, and the self-cutting of the object 200 starts from the phase shift region. Can be done.

Next, the object processing method will be described.

An object processing method for self-cutting an object by using a laser may include generating a laser beam in the laser light source 300, correcting a divergence angle of the generated laser beam, and correcting the corrected laser beam inside the object 200. Condensing on to form a spot (P). Here, the shape or size of the spot is adjusted by the divergence angle correction of the laser beam, the phase shift region is formed in the interior of the object 200 by the spot, the self-cutting of the object can be made from the phase shift region. .

In addition, the object processing method for self-cutting the object having a laminated portion formed on the surface using a laser, generating a laser beam in the laser light source 300, correcting the divergence angle of the generated laser beam, Concentrating the laser beam inside the object 200 to form a spot (P). Here, the shape or size of the spot is adjusted by the divergence angle correction of the laser beam, the phase shift region is formed in the interior of the object 200 by the spot, the self-cutting of the object can be made from the phase shift region. .

Here, the laminate may include a nitride layer or a metal layer. In addition, the nitride layer may include a gallium compound. In addition, the object 200 may be a semiconductor substrate or a sapphire substrate. In addition, the laser beam may be incident through the rear surface of the object 200 in which the lamination part is not formed.

In addition, in the phase change region, a stress concentration part may be formed at an end portion of the front surface or the rear surface of the object 200. In addition, the radius of curvature of the phase shift region may be minimum at the stress concentration portion. In addition, the phase change region T may not reach the surface or the rear surface of the object 200.

On the other hand, the step of calibrating the divergence angle of the laser beam, passing the laser beam through the cylindrical concave lens 411, and the laser beam passing through the cylindrical concave lens 411 the cylindrical convex lens ( 412 may be passed (see FIG. 2). Here, the cylindrical concave lens 411 and the cylindrical convex lens 412 can substantially correct the divergence angle of the laser beam in the same direction. In addition, the width of the spot may be changed by changing the distance between the cylindrical concave lens 411 and the cylindrical convex lens.

On the other hand, correcting the divergence angle of the laser beam, passing the laser beam through the spherical concave lens 413, the laser beam passed through the spherical concave lens 413, the first cylindrical convex lens 414 ), And passing the laser beam passed through the first cylindrical convex lens 414 to the second cylindrical convex lens 415 (see FIG. 4).

The first cylindrical convex lens 414 corrects the first divergence angle of the laser beam, and the second cylindrical convex lens 415 diverges the second direction of the laser beam substantially perpendicular to the first direction. You can correct the angle. Here, the first direction may be a direction orthogonal to the long axis of the spot (the X-axis direction or the width direction of the spot), and the second direction may be a direction parallel to the long axis of the spot (the Y-axis direction or the longitudinal direction of the spot). have. In addition, the direction parallel to the long axis of the spot may be a direction in which the line to be cut of the LED substrate is formed, that is, a scribing direction.

Meanwhile, the width of the spot may be changed by changing the position of the first cylindrical convex lens 414 between the spherical concave lens 413 and the second cylindrical convex lens 415. In addition, the length of the spot may be changed by changing the position of the second cylindrical convex lens 415 between the first cylindrical convex lens 414 and the condenser lens 430.

The object processing method may further include passing the corrected laser beam through the beam stopper 420 after correcting the divergence angle of the laser beam.

On the other hand, concentrating the laser beam inside the object 200 to form a spot may include passing the laser beam through the condenser lens 430.

Meanwhile, a plurality of spots may be formed in the vertical direction in the interior of the object 200 by changing the distance between the condenser lens 430 and the object 200. In addition, by changing the relative position of the object 200 with respect to the spot in the horizontal direction along the line to be cut, a plurality of spots may be formed in the horizontal direction inside the object 200. In addition, a scheduled line of cutting of the object 200 is formed along the horizontal direction, and the long axis direction of the spot may substantially coincide with the horizontal direction.

The object processing method may further include cutting the object 200 along the scheduled cutting line.

In the object processing method for self-cutting the object 200 using a laser, the laser beam generated by the laser light source is passed through the beam shaping module 410 to correct the divergence angle, and then the corrected laser beam is converted into the object ( By condensing in the interior of the object 200, a phase change region having a stress concentration part inside the object 200 may be formed.

In addition, the object processing method for self-cutting the object 200 having a laminated portion formed on the surface by using a laser, after passing the laser beam generated by the laser light source through the beam shaping module 410 to correct the divergence angle, By condensing the calibrated laser beam inside the object 200, a phase change region having a stress concentration part may be formed in the object 200.

Here, self-cutting may be performed from the stress concentration part toward the surface of the object in which the lamination part is formed.

An object processing method using a laser will be described in more detail with reference to the drawings.

FIG. 10 is a plan view schematically illustrating a wafer as an example of an object according to an exemplary embodiment of the present invention, FIG. 11 is a plan view illustrating a substrate on which phase shift regions are formed, and FIG. 12 is a horizontal view illustrating a substrate on which two interphase transition regions are formed. 13 is a vertical cross-sectional view showing a substrate on which a phase change region is formed.

First, as shown in FIG. 10, the object 200 to be scribed with a predetermined interval of cutting lines L1 and L2 orthogonal to each other on the surface is positioned on the mounting table 100.

Next, after generating and outputting a laser beam from the laser light source 300, diverging the output laser beam, and correcting the divergence angle, the corrected laser beam is condensed inside the object 200 to spot P To form.

When the spot P1 is formed inside the perpendicular to the cutting line L1 to avoid the stacking part 220 formed on the surface of the object 200, the phase change region T is formed around the spot P1. (See FIG. 11 (a)). Thereafter, the mounting table 100 is moved to change the relative position of the object 200 with respect to the condenser lens 430 so that the spots P2 and P3 are to be cut in the interior of the object 200. To be formed adjacent to the spot P1 in the horizontal direction (see FIGS. 11B and 11C).

In this case, the scheduled cutting line L of the object 200 is formed along the horizontal direction, and the major axis direction of the spot P substantially coincides with the horizontal direction.

12 shows the case where all the spots P needed on the cutting lines L1 and L2 are formed. The phase change region T is formed to be connected around the spot P inside the object 200. 13 is a vertical cross-sectional view of the object 200 in which the phase change region T is formed.

After the phase change region T is formed inside the object 200, the object 200 is separated along the cut line L, starting from the phase change region T. FIG.

Specifically, the object 200 is cut by applying an external force to the phase change region T from the outside so that cracks are formed from the phase change region T toward the front and rear surfaces of the object 200.

For example, both sides of the object 200 are fixed with a jig or the like about the cutting line L, and both sides of the object 200 are bent around the cutting line L, or the pressing member has a tip. By moving upward from the rear surface side of the object 200 along the cutting line (L), an external force is applied from the rear surface of the object 200 toward the upper side. In this case, cracks are formed in the direction from the phase change region T toward the surface of the object 200 to cut the object 200.

Alternatively, a method of cutting by applying an external force downward from the surface of the object 200 or by attaching an extension film to the back surface of the object 200 and expanding it in a plane direction to apply a tensile force to the object 200 to cut it. There is also.

In one embodiment of the present invention by precisely adjusting the depth of the spot (P), the crack is generated from the phase change area (T) to the surface or the rear surface of the object 200, the crack is the surface of the object 200 Or it can be self-cut as a result by reaching the back side as already described. At this time, when the thickness of the object 200 is thick, the distance between the condenser lens and the object 200 is changed, and a plurality of spots P are arranged in the vertical direction in the interior of the object 200 (P1, P2). It can also be formed. Thereafter, the object 200 is cut by applying an external force or by self cutting. In the case of the object 200 in which the self-cutting is performed, the subsequent cutting process may be unnecessary, but it is also possible to perform the cutting or separating process as described above to more surely separate the chip into chips.

The foregoing description of the present invention is intended for illustration, and it will be understood by those skilled in the art that the present invention may be easily modified in other specific forms without changing the technical spirit or essential features of the present invention. will be.

It is therefore to be understood that the above-described embodiments are illustrative in all aspects and not restrictive. For example, each component described as a single type may be implemented in a distributed manner, and similarly, components described as distributed may be implemented in a combined form.

The scope of the present invention is shown by the following claims rather than the above description, and all changes or modifications derived from the meaning and scope of the claims and their equivalents should be construed as being included in the scope of the present invention. do.

Claims (8)

Beam shaping module used in laser processing equipment,
A cylindrical concave lens for emitting a laser beam; And
It includes a cylindrical convex lens for correcting the divergence angle of the laser beam passing through the cylindrical concave lens,
At least one lateral length of a spot of the laser beam formed on the object is changed by the divergence angle correction of the laser beam,
The focal length of the cylindrical concave lens is f _c1 , the focal length of the cylindrical convex lens is f _v1 , the divergence angle of the laser beam is θ, and the focal length of the cylindrical concave lens lengthened by the divergence angle of the laser beam. If the increase component of a (θ) and the increase component of the focal length of the cylindrical convex lens lengthened by the divergence angle of the laser beam are b (θ), the cylindrical concave lens having the minimum size of the spot And the distance d` _f1 between the cylindrical convex lens is

Beam shaping module, characterized in that.
The method of claim 1,
And the cylindrical convex lens and the cylindrical convex lens are arranged to correct a divergence angle in substantially the same direction of the laser beam.
The method according to claim 1 or 2,
And a moving unit for moving at least one of the cylindrical concave lens and the cylindrical convex lens such that a distance between the cylindrical concave lens and the cylindrical convex lens is changed.
Beam shaping module used in laser processing equipment,
A spherical concave lens for emitting a laser beam;
A first cylindrical convex lens for correcting the divergence angle of the laser beam passing through the spherical concave lens; And
A second cylindrical convex lens for correcting the divergence angle of the laser beam passing through the first cylindrical convex lens,
At least one lateral length of the spot of the laser beam formed on the object is changed by the divergence angle correction of the laser beam,
When the vertical size of the phase change region formed inside the object by the spot is D, and the radius of curvature of the specific point of the phase change region is R, the degree of stress generated at the specific point of the phase change region is R. The stress concentration coefficient (S) is

Beam shaping module, characterized in that.
The method of claim 4, wherein
The first cylindrical convex lens corrects a first direction divergence angle of the laser beam, and the second cylindrical convex lens corrects a second direction divergence angle of the laser beam substantially orthogonal to the first direction; And a first cylindrical convex lens and a second cylindrical convex lens.
The method according to claim 4 or 5,
The spherical concave lens, the first cylindrical convex lens, and the second cylindrical convex lens such that a relative distance between the spherical concave lens, the first cylindrical convex lens, and the second cylindrical convex lens is changed. Beam shaping module further comprises a moving unit for moving one or more of the.
The method according to claim 1 or 4,
And the laser beam has a Gaussian beam profile.
The method according to claim 1 or 4,
And the laser beam is a pulse type laser beam.

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