APPARATUS AND METHOD FOR MANUFACTURING LIGHT- EMITTING DIODE

Technical Field

[ 1 ] This application claims the benefit of Korean Application Nos. 10-2008-0093223 filed on September 23, 2008, 10-2008-0097806 filed on October 6, 2008, and 10-2009-0033107 filed on April 16, 2009, all of which are hereby incorporated by reference for all purposes as if fully set forth herein.

[2] The present invention relates to an apparatus and method for manufacturing a light- emitting diode, and more particularly to an apparatus and method for manufacturing a light-emitting diode, which is capable of separating a thin film from a substrate to manufacture a vertical type light-emitting diode. Background Art

[3] A light-emitting diode (hereinafter, referred to as "LED") is a well-known semiconductor device for converting current into light. The LED emits light when electrons in an active layer made of semiconductor, which are excited from a valence band to a conduction band across a band gap, transit the valence band. This transition of the electrons enables the emission of light depending on band gap energy. Thus, wavelength or color of the light emitted by the LED is determined based on the semiconductor of the active layer since the band gap is one of the specific characteristics of a corresponding material.

[4] The LED is used for emitting light of various ranges of colors such as red, green, blue, and yellow. However, the LED has a limitation in that it is a monochromatic light source. There may be a requirement for emission of white light which includes all of the red, green, and blue lights. For example, a notebook computer using a liquid crystal display (hereinafter, referred to as "LCD") inevitably requires a backlight unit emitting white light. Typically, the white light is provided by an incandescent bulb or a fluorescent lamp. In case of the incandescent bulb, it is advantageous in that it is inexpensive, but it has very short lifetime and low light-emitting efficiency. The fluorescent lamp has higher light-emitting efficiency than the incandescent bulb, but the fluorescent lamp is disadvantageous in that its lifetime is limited. In addition, the fluorescent lamp requires a relatively large, heavy, and expensive additional component such as a stabilizer.

[5] A light source of white LED may be manufactured by closely positioning red, green, and blue LEDs which respectively emit light at an appropriate ratio. However, a process for manufacturing the blue LED is not easy since it is difficult to make good- quality crystal with the appropriate band gap. Particularly, if using compound semiconductor of indium phosphide (InP), gallium arsenide (GaAs), and gallium phosphide (GaP), it is difficult to realize the blue LED with good quality.

[6] In spite of these difficulties, the GaN-based blue LED has been used commercially.

Especially, since the GaN-based blue LED was introduced to the market in 1994, a rapid development for technology of the GaN-based blue LED enable the GaN-based blue LED to surpass the incandescent bulb or fluorescent lamp in terms of efficiency in the field of illumination.

[7] In case of the InP-based, GaAs-based, and GaP-based LEDs, a semiconductor layer grows on a conductive substrate, whereby it is not difficult to manufacture a vertical type LED having a p-n junction structure. However, the GaN-based LED uses a substrate made of sapphire (Al ₂ O ₃ ) so as to reduce a crystal defect that might occur during the epitaxial growth of GaN. In this case, a horizontal type structure having both first and second electrodes formed on a top surface of epi layer has been generally adopted since sapphire is non-conductive.

[8] FIG. 1 and FIG. 2 illustrate a related art horizontal type LED using a sapphire substrate.

[9] As shown in FIG. 1 which is a cross section view illustrating a related art LED 10, an n-GaN layer 12, an active layer 13 having multiple quantum wells, a p-GaN layer 14, and a transparent conductive layer 15 are formed sequentially on a sapphire substrate 11. Then, a first electrode 16 is formed on a predetermined portion of the transparent conductive layer 15.

[10] Then, photoresist patterns (not shown) are formed on the transparent conductive layer 15 including the first electrode 16 by photolithography, wherein the photoresist patterns (not shown) are provided to expose predetermined portions of the transparent conductive layer 15 on which the first electrode 16 is not formed. The transparent conductive layer 15, the p-GaN layer 14, and the active layer 13 are selectively etched under such circumstance that the photoresist patterns are used as a mask. At this time, a portion of the n-GaN layer 12 is etched slightly. Wet etch is preferred to dry etch since GaN layer is difficult to etch.

[11] After removing the photoresist patterns by a strip process, a second electrode 17 is formed on the exposed n-GaN layer 12.

[12] As shown in FIG. 2 which is a top view of the related art LED 10, in case of the horizontal type structure, both the first and second electrodes 16 and 17 require a wire bonding, a chip size of the LED 10 should be large enough to ensure an electrode area, which acts as an obstacle to improvement of an output per unit area of a wafer. In addition, a manufacturing cost is increased due to complexity of the wire bonding in a packing process. [13] Further, using the non-conductive sapphire substrate 11 makes it difficult to emit externally-provided static electricity, thereby increasing failure possibility and lowering device reliability. Also, since the sapphire substrate 11 has low thermal conductivity, it is difficult to emit heat generated for an operation of the LED 10 to the external, which acts as a limitation in applying high electric current for high output power of the LED 10.

[14] To overcome the problems of the horizontal type LED 10 using the sapphire substrate 11, a vertical type LED, especially a vertical type LED whose final product does not have a sapphire substrate, has been studied and researched actively.

[15] FIGs. 3 to 7 illustrate sequential steps for manufacturing a vertical type LED.

[16] As shown in FIG. 3, serial GaN-based layers 30 including a GaN buffer layer 31, an n-GaN layer 32, a InGaN/GaN/AlGalnN active layer 33 having a multiple quantum well, and a p-GaN layer 34 are formed sequentially on a sapphire substrate 20 by a typical semiconductor process technology, for example, MOCVD (Metal Oxide Chemical Vapor Deposition) or MBE (Molecular Beam Epitaxy). If a thin film of GaN directly grows on a sapphire (Al ₂ O ₃ ) (001) substrate, a surface uniformity of the thin film might be adversely affected due to a lattice incoherency. In this respect, it is desirable to firstly form the GaN buffer layer 31 on the sapphire substrate 20, and then to form the other GaN-based layers on the GaN buffer layer 31. Typically, the sapphire substrate 20 has a thickness of about 330 to 430/an, and an entire thickness of the serial GaN-based layers 30 is less than about 10/im.

[17] Then, as shown in FIG. 4, a plurality of trenches 30b are formed through the serial

GaN-based layers 30 by an ICP RIE (Inductively Coupled Plasma Reactive Ion Etching) method. Each trench 30b defines an individual LED. Also, the trench 30b is provided to make the individual LED formed in a square of about 200/im long and 200/M wide. The trench 30b in itself has a width less than about 10μm. Since the hardness of the serial GaN-based layers 30 is good, the trenches 30b are formed by RIE (Reactive Ion Etching), especially ICP RIE. In order to form the trenches 30b, a photoresist (not shown) is coated on the GaN-based layers 30 by a spin coating, and then is treated with a selective exposure and development process, thereby forming photoresist patterns (not shown). Then, the GaN-based layers 30 are partially etched by the ICP RIE using the photoresist patterns as an etching mask, thereby forming the plurality of trenches 30b.

[18] In comparison with an energy density of beam spot, the beam spot has such a large size as to cause fracture or crack at the GaN-based epi layer by a stress concentrated at the edge of the beam spot. Thus, a process for forming the trenches 30b is inevitable. That is, the stress causing the fracture or crack of the GaN-based layers 30a should be discharged through the trenches 30b when performing a laser lift-off process so as to separate the sapphire substrate 20 from the GaN-based layers 30a. Thus, it has been widely known that the process for forming the trenches 30b is inevitably performed before the laser lift-off process.

[19] After forming the trenches 30b, as shown in FIG. 5, a conductive supporting layer 40 is formed on the GaN-based layers 30a.

[20] Then, the sapphire substrate 20 is separated from the GaN-based layers 30a. In order to separate the sapphire substrate 20 from the GaN-based layers 30, laser beam passing through a beam homogenizer (not shown) is applied to the GaN-based layers 30a through the sapphire substrate 20 under such circumstances that the sapphire substrate 20 and the conductive supporting layers 40 are pulled in the opposite directions through the use of vacuum chucks (not shown) adhered thereon. At this time, since the stress is concentrated at the edge of the laser beam spot (A), the edge of the laser beam spot (A) should be applied to the trenches 30b. Thus, it causes difficulties related with precise adjustments for irradiation of laser beam pulse and movement of a stage with a wafer loaded thereon.

[21] According as the laser beam is sequentially applied to an entire area of a interface between the sapphire substrate 20 and the GaN-based layers 30a through the sapphire substrate 20, the sapphires substrate 20 is separated from the GaN-based epi layer 30a. In this case, the remaining epi layer 30a includes the GaN buffer layer 31 which was in contact with the sapphire substrate 20. Thus, it is necessary to additionally perform a process for removing the GaN buffer layer 31.

[22] As shown in FIG. 6, after removing the GaN buffer layer 31 , a contact layer 50 is formed on the respective n-GaN layers 32a.

[23] After forming the contact layer 50, the individual LEDs are divided by a dicing process. The dicing process may be performed by various mechanical or chemical methods. FIG. 7 illustrates a cross section view illustrating the final product divided as the individual LED. Disclosure of Invention Technical Problem

[24] Accordingly, the present invention is directed to an apparatus and method for manufacturing an LED that substantially obviates one or more of the problems due to limitations and disadvantages of the related art.

[25] An aspect of the present invention is to provide an apparatus and method for manufacturing an LED, which is capable of improving the yield by omitting a process of forming a trench in a GaN-based epi layer before a process of separating a sapphire substrate from the GaN-based epi layer.

[26] Another aspect of the present invention is to provide an apparatus and method for manufacturing an LED, which is capable of preventing damage to a GaN-based epi layer, the damage caused by imprecisely aligning an edge of beam spot with a trench in the GaN-based epi layer for a laser lift-off process of separating a sapphire substrate from the GaN-based epi layer, thereby realizing simplification and easiness in process.

[27] Another aspect of the present invention is to provide an apparatus and method for manufacturing an LED, which is capable of improving the yield by omitting a process for removing a GaN buffer layer after separating a sapphire substrate from a GaN- based epi layer.

[28] Additional features and aspects of the invention will be set forth in the description which follows, and in part will be apparent from the description, or may be learned by practice of the invention. The objectives and other advantages of the invention will be realized and attained by the structure particularly pointed out in the written description and claims hereof as well as the appended drawings. Technical Solution

[29] To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described, there is provided an apparatus for manufacturing an LED comprising a laser beam source for emitting laser beam; a mesh-typed mask having a plurality of apertures for selectively passing the laser beam; and an imaging lens for forming a plurality of beam spots by focusing the laser beam passing through the mesh-typed mask, so as to separate a substrate from a semiconductor layer formed on the substrate.

[30] In another aspect of the present invention, there is provided a method for manufacturing an LED comprising forming a semiconductor layer on a substrate; forming a conductive supporting layer on the semiconductor layer; forming a plurality of unit beams by passing a laser beam through a mesh-typed mask having a plurality of apertures; and forming a plurality of beam spots at an interface between the semiconductor layer and the substrate, wherein the plurality of beam spots are formed by passing the plurality of unit beams through an imaging lens.

[31] It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed.

Brief Description of Drawings

[32] The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.

[33] In the drawings: [34] FIGs. 1 and 2 illustrate a related art horizontal type LED;

[35] FIGs. 3 to 7 illustrate a related art process for manufacturing a vertical type LED;

[36] FIGs. 8 to 12 illustrate a process for manufacturing a vertical type LED according to one embodiment of the present invention;

[37] FIG. 13 illustrates an apparatus for manufacturing an LED according to the first embodiment of the present invention;

[38] FIG. 14 illustrates a mesh-typed mask according to one embodiment of the present invention;

[39] FIG. 15 illustrates an apparatus for manufacturing an LED according to the second embodiment of the present invention;

[40] FIGs. 16 to 19 illustrate various embodiments of beam expanding telescope (BET) according to the present invention; and

[41] FIGs. 20 to 23 illustrate apparatuses for manufacturing an LED according to the third to sixth embodiments of the present invention. Mode for the Invention

[42] Reference will now be made in detail to an embodiment of the present invention, example of which is illustrated in the accompanying drawings.

[43] Hereinafter, an apparatus and method for manufacturing an LED according to the present invention will be described with reference to the accompanying drawings.

[44] According to one embodiment of the present invention, as shown in FIG. 8, serial

GaN-based epi layers 200 including a GaN buffer layer 210, an N-type GaN layer 220, a InGaN/GaN/ AlGaInN active layer 230 having a multiple quantum well, and a P-type GaN layer 240 are sequentially formed on a sapphire substrate 100 by a typical semiconductor process technology, for example, MOCVD (Metal Oxide Chemical Vapor Deposition) or MBE (Molecular Beam Epitaxy).

[45] If a thin film of GaN grows on a sapphire (Al ₂ O ₃ ) (001) substrate, a surface uniformity of the thin film might be adversely affected due to a lattice incoherency. In this respect, it is desirable to firstly form the GaN buffer layer 210 on the sapphire substrate 100, and then to sequentially form the other GaN-based layers 220, 230, and 240 on the GaN buffer layer 210. Typically, the sapphire substrate 100 has a thickness of about 330 to 430/ffli, and an entire thickness of the serial GaN-based layers 200 is less than about 10/im.

[46] Then, as shown in FIG. 9, a conductive supporting layer 300 is formed on the GaN- based epi layer 200. The conductive supporting layer 300 may be formed by physical vapor deposition, electroplating, or bonding. It is preferable that the conductive supporting layer 300 have about 500/αn thickness or less, but not necessarily. The conductive supporting layer 300 is formed of metal, for example, Cu, Au, or Al. However, the conductive supporting layer 300 may be formed of any material with an electrical conductivity such as Si.

[47] In order to enhance an adhesive strength between the GaN-based epi layer 200 and the conductive supporting layer 300, an adhesive layer (not shown) including Cr or Au may be additionally provided therebetween.

[48] Then, the sapphire substrate 100 is separated from the GaN-based epi layer 200 by a laser lift-off process. This separation may be performed by applying laser beam to the GaN-based epi layer 200 through the sapphire substrate 100.

[49] According to one embodiment of the present invention, the process of separating the sapphire substrate 100 includes a step for forming a plurality of beam spots (B) on an interface between the GaN-based epi layer 200 and the sapphire substrate 100 by making the laser beam pass through a mesh-typed mask having a plurality of apertures.

[50] FIG. 13 illustrates an apparatus 500a for manufacturing an LED according to the first embodiment of the present invention, and FIG. 14 illustrates a mesh-typed mask 520 according to one embodiment of the present invention.

[51] The apparatus 500a according to the first embodiment of the present invention may be a laser lift-off apparatus, which includes a laser beam source 510 for emitting laser beam; a mesh-typed mask 520 provided with a plurality of apertures 521 for selectively passing the laser beam emitted from the laser beam source 510; and an imaging lens 530 for forming a plurality of beam spots (B) by focusing the laser beam passing through the plurality of apertures 521 in the mesh-typed mask 520 on a target.

[52] The wavelength of the laser beam may be between about 150 nm and about 1100 nm.

The laser beam source 510 may be KrF eximer laser or ArF eximer laser.

[53] The target corresponds to the GaN-based epi layer 200 formed on the sapphire substrate 100. The plurality of beam spots (B) are formed on the interface between the GaN-based epi layer 200 and the sapphire substrate 100. That is, the laser beam is firstly divided into a plurality of unit beams by passing through the plurality of apertures 521 in the mesh-typed mask 520, the divided unit beams are focused by the imaging lens 530, and then focused beam is applied to the GaN-based epi layer 200 through the sapphire substrate 100, thereby forming the plurality of beam spots (B) on the interface between the GaN-based epi layer 200 and the sapphire substrate 100.

[54] According to one embodiment of the present invention, each of the beam spots (B) is formed in a circular shape satisfying the following formula:

[55] 1.67XlO ³ XTxE _d ¹ < R < 2OxIO ³ XTxE _d ¹

[56] wherein R represents the semi-diameter(m) of the circular shape, T represents the thickness(m) of the GaN-based epi layers 200, and E _d represents the energy density(J/cm ² ) of the beam spot (B). Generally, the thickness of the GaN-based epi layer 200 is about 5 to 10/im, and the appropriate energy density of the beam spot (B) is about 0.6 to 2J/cm ² . Thus, each beam spot (B) has the semi-diameter of about 0.4 to 32/zm, and more preferably about 5 to 20/im, but not necessarily.

[57] In order to uniformly disperse the stress applied to the GaN-based epi layer 200, it is preferable that the beam spot (B) have the circular shape, but not necessarily. Also, if the semi-diameter of the beam spot (B) is less than the aforementioned range, the size of the beam spot (B) becomes excessively small, thereby lowering the efficiency and yield. If the semi-diameter of the beam spot (B) is above the aforementioned range, the size of the beam spot (B) becomes excessively large as compared with the energy density of the beam spot (B), whereby the stress is excessively concentrated at the edge of the beam spot (B), which might cause the fracture or crack in the GaN-based epi layer 200.

[58] According to one embodiment of the present invention, when applying the laser beam to the sapphire substrate 100, the size of the beam spot (B) is adjusted to be proportional to the thickness of the GaN-based epi layer 200 on the sapphire substrate 100, and to be inversely proportional to the energy density of the beam spot (B), thereby preventing the fracture or crack from occurring in the GaN-based epi layer 200 by the stress concentrated at the edge of the beam spot (B).

[59] According to the present invention, there is no requirement for forming a trench

(through which the stress concentrated at the edge of the beam spot is discharged to the external) in the GaN-based epi layer 200 before the laser lift-off process for separating the sapphire substrate 100 from the GaN-based epi layer 200. Also, since the plurality of beam spots (B) having the appropriate size are formed from the laser beam, it is possible to maximize the efficiency and yield.

[60] The size of the beam spot (B) can be adjusted by changing the position of the mesh- typed mask 520. In this case, all optical elements have to be re-aligned based on the change in position of the mesh-typed mask 520, and the energy density of the beam spot (B) applied to the sapphire substrate 100 is changed. Thus, it is more desirable that the size of the beam spot (B) should be adjusted by changing the size of the aperture 521 in the mesh-typed mask 520, but not necessarily.

[61] If each aperture 521 has a diameter 'D', it is preferable that a pitch between the neighboring apertures 521 be less than '2D' in terms of the efficiency and yield.

[62] As shown in FIG. 9, it is unnecessary to precisely align the respective edges of the plurality of beam spots (B), formed on the interface between the GaN-based epi layer 200 and the sapphire substrate 100, with respective LEDs (C) through the use of laser beam. Thus, there is no requirement for precise timing control for the laser beam irradiation and wafer movement, whereby the process can be simplified and easily done with minimum errors.

[63] As shown in FIGs. 10 and 11, while the wafer is moved in the X-axis direction, a first pulse for forming the plurality of beam spots (B 1), a second pulse for forming the plurality of beam spots (B2), and a third pulse for forming the plurality of beam spots (B3) are sequentially applied to the wafer, to thereby divide the sapphire substrate 100 into the individual LEDs (C). Selectively, while a stage with the wafer loaded thereon is moved in the Y-axis direction or X-Y axis direction, the laser beam may be applied thereto.

[64] According as the laser beam pulse is applied according to the aforementioned method, the entire area of the interface beteen the GaN -based epi layer 200 and the sapphire substrate 100 may be repeatedly irradiated with the laser beam. In this case, the GaN buffer layer 210 being in direct contact with the sapphire substrate 100 may be completely removed for the laser lift-off process. According to the present invention, there is no requirement for an additional process for removing the GaN buffer layer 210 after the laser lift-off process, thereby maximizing the efficiency and yield.

[65] The circular shape of the beam spot (B) enables the uniform dispersion of the stress applied to the GaN-based epi layer 200 so that the stress concentrated at the edge of the beam spot can be minimized. However, the geometrical arrangement of the circular- shaped beam spots (B) may cause different numbers of laser-beam irradiation applications according to the respective positions of the sapphire substrate 100. That is, the number of laser-beam irradiation applications may be different according to the corresponding position of the respective areas of the sapphire substrate 100.

[66] In order to identically apply the laser beam to the entire area of the sapphire substrate

100 by the same number of laser-beam irradiation applications, the beam spot may be formed in a rectangular shape. For providing the rectangular- shaped beam spot, the mesh-typed mask 520 may have a rectangular-shaped aperture. In this case, the size of the rectangular- shaped beam spot may be the same as or smaller than the size of the circular-shaped beam spot, to thereby prevent the GaN-based epi layer 200 from being damaged by the stress concentrated at the edge of the beam spot.

[67] After the laser lift-off process, a contact layer 400 is formed on the N-type GaN layer

220, and is then divided into the individual LEDs by a dicing process. The dicing process may be performed by various mechanical or chemical methods. FIG. 12 illustrates a cross section view illustrating the final product divided as the individual LED.

[68] FIG. 15 illustrates an apparatus 500b for manufacturing an LED according to the second embodiment of the present invention.

[69] The apparatus 500b according to the second embodiment of the present invention further includes a beam expanding telescope (BET) 540 positioned between a laser beam source 510 and a mesh-typed mask 520. Except that, the apparatus 500b is provided with the same optical elements as those included in the apparatus 500a according to the first embodiment of the present invention.

[70] The beam expanding telescope (BET) 540 expands laser beam emitted from the laser beam source 510, to thereby expand a laser-beam irradiation area. According as the expanded laser beam passes through more apertures 52 in the mesh-typed mask 520 as compared to the first embodiment of the present invention, more beam spots (B) are formed on a sapphire substrate 100, thereby improving the yield.

[71] FIGs. 16 to 19 illustrate various embodiments of the beam expanding telescope

(BET) 540 according to the present invention.

[72] As shown in FIG. 16, the beam expanding telescope (BET) 540 includes a cylindrical concave lens 514 and a cylindrical convex lens 542 aligned in sequence. Thus, the laser beam incident on the beam expanding telescope (BET) 540 is expanded only in the single axis (Y-axis). For expanding the laser beam in the single axis, the beam expanding telescope (BET) 540 may include two cylindrical convex lenses, wherein the laser beam is focused on an optical path between the two cylindrical convex lenses.

[73] As shown in FIG. 17, the beam expanding telescope (BET) 540 includes a spherical concave lens 543 and a spherical convex lens 544 aligned in sequence. Thus, the laser beam incident on the beam expanding telescope (BET) 540 is expanded in the both axes (X-Y axes).

[74] As shown in FIG. 18, the beam expanding telescope (BET) 540 includes a spherical concave lens 545 and two cylindrical convex lenses 546 and 547 aligned in sequence. In this case, the two cylindrical convex lenses 546 and 547 are perpendicular in their curvature directions so that the laser beam incident on the beam expanding telescope (BET) 540 is expanded in the both axes.

[75] As shown in FIG. 19, the beam expanding telescope (BET) 540 includes two cylindrical concave lenses 548a and 548b and two cylindrical convex lenses 549a and 549b aligned in sequence. According as a curvature direction of each lens is perpendicular to a curvature direction of the neighboring lens, the laser beam incident on the beam expanding telescope (BET) 540 is expanded in the both axes.

[76] FIGs. 20 to 23 illustrate apparatuses for manufacturing an LED according to the third to sixth embodiments of the present invention.

[77] As shown in FIG. 20, the apparatus 500c for manufacturing an LED according to the third embodiment of the present invention further includes a field lens 550 positioned between a laser beam source 510 and a mesh-typed mask 520. Except that, the apparatus 500c according to the third embodiment of the present invention is provided with the same optical elements as those included in the apparatus 500a according to the first embodiment of the present invention. The field lens 550 may be a convex lens or concave lens. If the field lens 550 is the concave lens, the laser beam passing through the field lens 550 passes more apertures 520 in the mesh-typed mask 520 as compared with the first embodiment of the present invention, whereby the number of beam spots (B) formed on a sapphire substrate 100 is relatively high, but the energy density of each beam spot (B) becomes low. If the field lens 550 is the convex lens, the number of beam spots (B) formed on a sapphire substrate 100 is relatively low, but the energy density of each beam spot (B) becomes high.

[78] As shown in FIG. 21, the apparatus 500d for manufacturing an LED according to the fourth embodiment of the present invention further includes a beam expanding telescope (BET) 540 positioned between a laser beam source 510 and a field lens 550. Except that, the apparatus 500d according to the fourth embodiment of the present invention is provided with the same optical elements as those included in the apparatus 500c according to the third embodiment of the present invention. As mentioned above, the beam expanding telescope (BET) 540 may expand the laser beam in the singular axis or both axes. The beam expanding telescope (BET) 540 enables to form more beam spots (B) on a sapphire substrate 100, thereby improving the yield.

[79] As shown in FIG. 22, the apparatus 500e for manufacturing an LED according to the fifth embodiment of the present invention further includes a beam homogenizer 560 positioned between a beam expanding telescope (BET) 540 and a mesh-typed mask 520. Except that, the apparatus 500e according to the fifth embodiment of the present invention is provided with the same optical elements as those included in the apparatus 500b according to the second embodiment of the present invention. The beam homogenizer 560 improves uniformity in energy intensity of the laser beam expanded by the beam expanding telescope (BET) 540, whereby beam spots (B) with uniform energy intensity profile are formed on a sapphire substrate 100.

[80] As shown in FIG. 23, the apparatus 500f for manufacturing an LED according to the sixth embodiment of the present invention further includes a field lens 550 positioned between a beam homogenizer 560 and a mesh-typed mask 520, for adjusting an interval therebetween. Except that, the apparatus 500f according to the sixth embodiment of the present invention is provided with the same optical elements as those included in the apparatus 500e according to the fifth embodiment of the present invention.

[81] Accordingly, the apparatus and method for manufacturing an LED according to the present invention has the following advantages.

[82] The apparatus and method for manufacturing an LED according to the present invention can improve the yield by omitting the troublesome process for forming the trench in the GaN-based epi layer 200 before the process for separating the sapphire substrate 100 from the GaN-based epi layer 200.

[83] Also, the apparatus and method for manufacturing an LED according to the present invention is capable of preventing damage to the GaN-based epi layer 200, the damage caused by imprecisely aligning the edge of beam spot (B) with the trench in the GaN- based epi layer for the laser lift-off process of separating the sapphire substrate 100 from the GaN-based epi layer 200, thereby realizing simplification and easiness in process.

[84] Furthermore, after separating the sapphire substrate 100 from the GaN-based epi layer 200, there is no requirement for the process of removing the GaN buffer layer 210, which enables the improved yield. Industrial Applicability

[85] It will be apparent to those skilled in the art that various modifications and variation can be made in the present invention without departing from the spirit or scope of the invention. Thus, it is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.