KR101078469B1 - Light emitting diode chip and method of manufacturing the same - Google Patents

Abstract

In an embodiment, the LED chip includes a crystalline substrate, an LED device disposed on the crystalline substrate, and a refractive index buffer layer positioned on at least one of the side and bottom surfaces of the crystalline substrate and translucent.

Description

Light emitting diode chip and method of manufacturing the same

The present application generally relates to a light emitting diode device, and more particularly to a light emitting diode chip having a refractive index buffer layer on the side and / or bottom and a method of manufacturing the same.

Light emitting diode (LED) devices are photoelectric conversion devices that emit light by applying a forward current to both ends of a P-N junction. In general, LED devices are released to commercial products through epi wafer fabrication, chip production, packaging, and module processes. Recently, as the LED device is applied to a device that requires high power, such as a lighting fixture, the study of the LED device is actively progressed in the field of increasing the efficiency of the LED, such as internal quantum efficiency, light extraction efficiency.

As a technique for increasing the efficiency of the LED, for example, in the process of manufacturing an epi wafer, a technique for reducing crystal defects acting as a non-emitting center, a technique for promoting efficient recombination of electrons and holes in an active layer, and the like are studied. have. In addition, in the chip production process, techniques such as chip shape design, flip chip process optimization design, and vertical chip design for increasing light emission efficiency have been attempted. In the packaging process and the module process, heat emission improvement techniques that affect the light conversion efficiency have been studied.

In particular, in relation to the light extraction efficiency, which means the ratio of photons generated in the active layer region of the LED device to the outside, the photons are affected by the difference in refractive index between the two materials, such as the interface between the substrate and the epi layer while being emitted to the outside. A certain amount of reflection at the interface of the material is generated. In this case, as the light undergoes multiple reflections, the extinction rate of photons may increase, thereby lowering the light extraction efficiency. Usually, about 8% is emitted from the upper surface of the chip to the outside, about 20% is emitted through the substrate under the chip, and about 72% is lost to the inside of the chip without being released to the outside of the chip. have. At present, various techniques have been attempted to prevent such deterioration of light extraction efficiency. For example, an epitaxial layer and a substrate serving as a reflector may be used to form a structure in which an LED device easily emits light. The technique which isolate | separates, the technique which prevents total reflection by increasing the surface roughness of an LED element, etc. are mentioned.

Due to the research to increase the efficiency of the LED as described above, the recent industry has been able to obtain the light extraction efficiency of about 100 lm / W, and various efforts to increase the efficiency of such LED is in the future at the request of the industry It is expected to continue steadily.

The technical problem to be achieved by the present application is to provide an LED chip having improved light emission efficiency to increase the emission efficiency to the outside for the light emitted from the LED device to reach the lower crystalline substrate.

Another object of the present application is to provide a method of manufacturing an LED chip having the improved light emission efficiency.

An LED chip according to an aspect of the present application for achieving the above technical problem is disclosed. The LED chip includes a crystalline substrate, an LED device disposed on the crystalline substrate, and a refractive index buffer layer positioned on at least one of the side and bottom surfaces of the crystalline substrate and translucent.

Disclosed is a manufacturing method of an LED chip according to another aspect of the present application for achieving the above technical problem. In the method of manufacturing the LED chip, first, a light emitting structure in which the LED device is disposed on the crystalline substrate is formed. A transmissive refractive index buffer layer is formed on at least one of the side and bottom of the crystalline substrate.

According to the exemplary embodiment of the present application, the LED chip may have a refractive index buffer layer on at least one of the side and the bottom of the crystalline substrate, thereby more efficiently emitting the light inside the crystalline substrate to the outside.

According to one embodiment of the present application, by preparing an LED chip, and forming a film or a pattern on at least one of the side and bottom of the crystalline substrate, it is possible to easily improve the light emission efficiency.

1 is a view schematically showing an LED chip according to an embodiment of the present application.
2 is a cross-sectional view schematically showing an LED chip according to embodiments of the present application.
3 is a cross-sectional view schematically showing the function of the refractive index buffer layer according to an embodiment of the present application.
4 is a flowchart illustrating a method of manufacturing an LED chip according to an embodiment of the present application.
5 and 6 are cross-sectional views showing a method of manufacturing an LED chip according to an embodiment of the present application.
7 is a flowchart illustrating a method of manufacturing an LED chip according to another embodiment of the present application.

Embodiments of the present application will now be described in more detail with reference to the accompanying drawings. However, the techniques disclosed in this application are not limited to the embodiments described herein but may be embodied in other forms. It should be understood, however, that the embodiments disclosed herein are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the width, thickness, and the like of the components are enlarged in order to clearly express the components of each device. The description was made at the point of view of the observer as a whole, and one of ordinary skill in the art may realize the spirit of the present application in various other forms without departing from the technical spirit of the present application. In addition, in the drawings, the same reference numerals refer to substantially the same elements.

In addition, singular expressions should be understood to include plural expressions unless the context clearly indicates otherwise, and the terms “comprise,” “comprise,” or “have” should refer to features, numbers, processes, and operations described. To specify that an element, part or combination thereof exists, and not preclude the existence or addition of one or more other features or numbers, processes, operations, components, parts or combinations thereof in advance It must be understood.

In addition, the fact that the first component is “connected” to the second component not only means that the first component is directly connected to the second component, but also that the first component is connected to or via the third component. 2 Anything connected to or attached to a component shall be construed to include both.

In addition, the fact that the first component is disposed on or above the second component is not only when the first component is disposed directly on or directly on the second component. It is interpreted as including all when the 3rd component is interposed between the 1st component and the 2nd component.

In general, a manufacturing process of the LED chip includes an epi wafer manufacturing process, a chip production process, a packaging process process, and a module process process. In an exemplary embodiment of the present application, in the epi wafer manufacturing process, an N-type semiconductor layer, an active layer, and a hole, which provide electrons by growing an epitaxial compound semiconductor on an crystalline wafer used as a substrate, provide an electron. A semiconductor layer is formed. The active layer emits light by combining the electrons and holes. In an embodiment of the present application, in the chip production process, an N-type electrode and a P-type electrode which are electrically connected to the N-type semiconductor layer and the P-type semiconductor layer are formed, and a plurality of formed on the epi wafer. By cutting the LED elements into individual chips, the LED chips can be formed. In the packaging process, the individual chip is packaged to connect the manufactured LED chip with a lead and emit light to the outside. In the module processing step, the packaged LED chip is attached to a predetermined frame such as a PCB. The embodiments of the present application mainly disclose a technique for increasing the light emission efficiency of the LED chip in the chip production process, but the techniques of the embodiments are not excluded from being applied in other processes of the manufacturing process of the LED chip. .

The refractive index buffer layer described herein refers to a material layer disposed between two material layers having different refractive indices and having a refractive index between the refractive index values of the two material layers.

The surface region described in this specification is a concept that refers to both the region in contact with the surface of the base material such as a crystalline substrate and the region formed inside the predetermined depth from the surface.

1 is a view schematically showing an LED chip according to an embodiment of the present application. Specifically, FIG. 1A is a plan view schematically illustrating a crystalline wafer in which a plurality of LED devices are formed, and FIG. 1B is a crystalline wafer of FIG. 1A according to an embodiment. Detailed schematic diagram of the LED chip separated from the. Referring to FIG. 1A, a plurality of LED elements 110 formed on the crystalline wafer 100 are disposed through the epi wafer manufacturing process described above. Specifically, an active layer (not shown), an N-type semiconductor layer (not shown) for providing electrons to the active layer, and a P-type semiconductor layer (not shown) for providing holes in the active layer are formed on the crystalline wafer 100, An N-type electrode and a P-type electrode (not shown) are electrically connected to the N-type semiconductor layer and the P-type semiconductor layer. As such, a plurality of LED elements 110 are positioned on the crystalline wafer 100. In an embodiment, when the crystalline wafer is a sapphire single crystal wafer, the N-type semiconductor layer, the active layer, and the P-type semiconductor layer may be formed from a gallium nitride (GaN) -based compound semiconductor having different doping levels. In another embodiment, when the crystalline wafer is a GaP single crystal wafer, the N-type semiconductor layer, the active layer, and the P-type semiconductor layer may be formed from an aluminum gallium indium (AlGaInP) compound semiconductor having different doping levels. As described above, in the embodiments of the present application, various known materials constituting the light emitting device may be applied to the crystalline wafer, the N-type semiconductor layer, the active layer, and the P-type semiconductor layer.

The plurality of LED elements 110 formed on the crystalline wafer 100 are separated into the plurality of LED chips 120 through a dicing operation. According to one embodiment of the present application, the dicing method is an example using a diamond pencil, diamond saw (saw) or laser.

Referring to FIG. 1B, according to an embodiment of the present application, an individual LED chip 120 separated from the crystalline wafer 100 is schematically illustrated. The LED chip 120 includes a crystalline substrate 122 and an LED element 110 disposed on the crystalline substrate 122. The crystalline substrate 122 herein refers to a portion of the crystalline wafer 100 separated to correspond to the individual LED chips 120. The LED device 110 may include an N-type semiconductor layer (not shown), an active layer (not shown), a P-type semiconductor layer (not shown), an N-type electrode electrically connected to the N-type semiconductor layer, and the P-type semiconductor layer; P-type electrode (not shown) is included.

2 is a view schematically showing an LED chip according to embodiments of the present invention. Specifically, FIG. 2A is a schematic diagram schematically showing an LED chip according to an embodiment of the present application, and FIG. 2C is a cross-sectional view taken along the line AA ′ of FIG. 2A. to be. FIG. 2B is a schematic diagram schematically showing an LED chip according to another embodiment of the present application, and FIG. 2D is a cross-sectional view taken along the line BB ′ of FIG. 2B.

Referring to FIGS. 2A and 2C, the LED chip 220 includes a crystalline substrate 222, an LED element 210 disposed on the crystalline substrate, and a refractive index buffer layer 224. The LED device 210 includes a P-type semiconductor layer, an active layer, and an N-type semiconductor layer. The refractive index buffer layer 224 is positioned on at least one of the side and bottom of the crystalline substrate 222 and is translucent. The refractive index buffer layer 224 may be a layer covering at least one of the side and the bottom of the crystalline substrate 222. In FIGS. 2A and 2C, a refractive index buffer layer 224 is disposed on the side surface and the bottom surface of the crystalline substrate 222. In another embodiment, the refractive index buffer layer 224 may be disposed on either the side or the bottom of the crystalline substrate 222. The refractive index buffer layer 224 may be smaller than the refractive index of the crystalline substrate 222 and larger than the refractive index of air. As an example, the refractive index buffer layer 224 may be formed of indium tin oxide (ITO), indium phosphorous oxide (INPOx), indium arsenic oxide (glass), sodium chloride (sodium chloride), and the like. , NaCl), titanium oxide (TiO 2), quartz, or a combination thereof. The glass has a refractive index of about 1.46, about 1.5 of the sodium chloride, about 1.5 of the titanium oxide, and about 1.46 of the quartz.

Referring to FIGS. 2B and 2D, the LED chip 230 is substantially the same as the LED chip 220 except that the refractive index buffer layer 234 is disposed in a continuous or discontinuous pattern. The refractive index buffer layer 234 may be positioned in a pattern on at least one of side and bottom surfaces of the crystalline substrate 222. In the drawing, as an example, the refractive index buffer layer 234 is disposed in a local region in a discontinuous pattern on the side and bottom of the crystalline substrate 222. In another example, the refractive index buffer layer 234 may have various patterns and may be disposed in a continuous pattern or a discontinuous pattern on either the side or the bottom of the crystalline substrate 222, as shown in FIG. The refractive index buffer layer 234 may be smaller than the refractive index of the crystalline substrate 222 and larger than the refractive index of air. The refractive index buffer layer 234 is, for example, Indium Tin Oxide (ITO), Indium Phorphorus Oxide (InPOx), Indium Arsenic Oxide, Glass, Sodium Chloride , NaCl), titanium oxide (TiO 2), quartz, or a combination thereof. The glass has a refractive index of about 1.46, about 1.5 of the sodium chloride, about 1.5 of the titanium oxide, and about 1.46 of the quartz.

According to an embodiment, the refractive index buffer layers 224 and 234 may be an amorphous material layer pattern composed of the same components as the crystalline substrate 222. As an example, the substrate 122 may be made of single crystal sapphire, and the refractive index buffer layer 124 may be made of amorphous sapphire. The refractive index buffer layers 224 and 234 serve to improve the emission to the outside of the crystalline substrate 222 with respect to the light generated by the LED elements 210 and 212.

3 is a cross-sectional view schematically showing the function of the refractive index buffer layer according to an embodiment of the present application. FIG. 3 is substantially the same as FIG. 2D, which is a cross-sectional view of the LED chip 230 of FIG. 2B taken along the line B-B '. Referring to FIG. 3, the function of the refractive index buffer layer is described as the total reflection theory, which is one of several theories related to the refractive index. First, a part of the light generated from the LED element 212 proceeds to the lower crystalline substrate 222. . In order to increase the light extraction efficiency of the LED chip 330, the ratio of the light I ₃ emitted to the outside of the LED chip 330 among the lights I _{1 in the} crystalline substrate 222 must be increased. In general, when light reaches the interface of media having different refractive indices, the light is reflected or refracted and transmitted at the interface. As shown, when light I ₁ travels from the crystalline substrate 222, which is a relatively optically dense medium, into the outside air, at the interface between the crystalline substrate 222 and the air, a portion I ₃ is determined by the angle of incidence ( It may be refracted at an angle of refraction r greater than i) and part I2 may be reflected. When the magnitude of the incident angle i becomes larger than the predetermined critical angle i _c , which is determined by the refractive index n ₁ of the crystalline substrate 222 and the refractive index n ₂ of the air, the light is both at the interface of the two media. Reflection occurs, which is called total reflection. When total reflection occurs several times inside the LED chip, the light inside the LED chip may be trapped inside and disappeared without being emitted to the outside.

When the refractive index buffer layer 234 does not exist, the following phenomenon may occur when light traveling in the crystalline substrate 222 reaches an interface with air. By the law of refraction, sin i _c1 is represented by the refractive index n ₂ of air / the refractive index n ₁ of the crystalline substrate, and since the refractive index of air is 1, sin i _c1 = 1 / n ₁ . At the critical angle i _c1 at which total reflection occurs, the larger the refractive index n1 of the crystalline substrate is, the smaller the critical angle is. Thus, referring to FIG. 3, light propagating in the crystalline substrate 222 at the interface with the air. The probability of being reflected back into the crystalline substrate 222 is relatively increased.

The inventors of the present application devised a technique for disposing the refractive index buffer layer 234 at the interface between the crystalline substrate 222 and the outside air. The refractive index buffer layer 234 may be disposed in, for example, a local region of the crystalline substrate 222. The refractive index n ₃ of the refractive index buffer layer 234 is smaller than the refractive index n ₁ of the crystalline substrate 222 and larger than the refractive index n _{2 of} air. When the refractive index buffer layer 234 is present between the substrate 222 and the outside air, the critical angle i _c2 at the interface between the substrate 222 and the refractive index buffer layer 234 is represented by sin i _c2 = the refractive index of the refractive index buffer layer ( n ₃ ) / refractive index n _{1 of the} substrate. In addition, the critical angle (i _c3 ) at the interface between the refractive index buffer layer 234 and the outside air is expressed by sin i _c3 = refractive index n ₂ of air / refractive index n ₃ of the refractive index buffer layer. Since the refractive index is 1, the refractive index (n ₃₎ greater than the index of refraction smaller the refractive index of air than the (n ₁₎ (n ₂₎ of the substrate 222 of the _{sin i c3 = 1 / n 3} . refractive index buffer layer 234, The critical angle i _c2 and the critical angle i _c3 at each interface are larger than the critical angle i _c1 As such, the refractive index buffer layer 234 has the interface when the light inside the crystalline substrate 222 travels outward. It is possible to increase the critical angle at, thereby increasing the probability of emission of light propagating in the substrate 222 into the outside air, according to one embodiment, when the crystalline substrate 222 is single crystal sapphire, The refractive index of the crystalline substrate 222 is 1.77 and the refractive index of air is 1. At this time, the refractive index buffer layer 234 is amorphous Amorphous sapphire is an optically insignificant medium because it is crystallographically irregularly arranged than single crystal sapphire, and thus has a relatively low refractive index.

Another theory related to refractive index is described by way of example in Richard H.bube's Electrons in solids, third edition, academic press, inc. pp. 133-138, the following contents are disclosed. In the case where a material of a predetermined material and a vacuum are bound to each other and absorption of light at the interface is not important, the reflectance R at the interface with the vacuum of the light traveling in the material is estimated as follows.

R = (r-1) ² / (r + 1) ² (where r is the refractive index of the material and vacuum is 1)

------- Formula (1)

As expressed in Equation (1), assuming that light propagates in a material having a refractive index greater than 1, it can be seen that the reflectance at the interface with a vacuum increases as the refractive index of the material increases. have. Similarly, it can be seen that the reflectance at the interface with the air is lower when the refractive index buffer layer 234 is at the interface with the air than when the crystalline substrate 222 is at the interface with the air. Therefore, in the case where the refractive index buffer layer 234 and the air form an interface, the transmittance from the interface to the air increases.

As described above, the LED chip according to an embodiment of the present application is provided on at least one or more of the side and bottom of the crystalline substrate and has a refractive index buffer layer that is transparent. As a result, light emitted from the LED device and traveling inside the crystalline substrate may be increased to be emitted to the outside air through the side or bottom of the crystalline substrate.

4 is a flowchart illustrating a method of manufacturing an LED chip according to an embodiment of the present application. 5 and 6 are cross-sectional views showing a method of manufacturing an LED chip according to an embodiment of the present application. Referring to FIG. 4, in block 410, a light emitting structure in which an LED device is disposed is formed on a crystalline substrate. The process of block 410 may include a process of forming a plurality of LED elements on a crystalline wafer in block 412 and a process of cutting the crystalline wafer such that the plurality of LED elements are separated from each other at block 414.

According to an embodiment, in block 412, an N-type semiconductor layer, an active layer, and a P-type semiconductor layer are formed to epitaxially grow a compound semiconductor on the crystalline wafer. An N-type electrode and a P-type electrode are electrically connected to the N-type semiconductor layer and the P-type semiconductor layer. When the crystalline wafer is a sapphire single crystal wafer, the N-type semiconductor layer, the active layer and the P-type semiconductor layer may be formed from a gallium nitride (GaN) -based compound semiconductor having different doping levels. In the embodiments of the present application, a variety of known materials constituting the light emitting device may be applied to the crystalline wafer, the N-type semiconductor layer, the active layer, and the P-type semiconductor layer.

Thereafter, in block 414, the crystalline wafer on which the plurality of LED elements are formed is cut to separate the plurality of LED elements from each other. The cutting of the crystalline wafer may be, for example, a method of mechanically cutting using a diamond saw or a diamond pencil, or a method of cutting by irradiating a laser, and various other known methods may be applied. Detailed description will be omitted. Referring to FIG. 5A, an LED device 510 is formed on a crystalline substrate 522 by the above-described embodiment of the present application.

In block 420, a refractive index buffer layer is formed on at least one of the side and bottom of the crystalline substrate. The refractive index buffer layer is smaller than the refractive index of the crystalline substrate and larger than the refractive index of air. The refractive index buffer layer may perform a function of improving emission to the outside of the crystalline substrate with respect to light generated by the LED device.

In one embodiment, in the step of forming the refractive index buffer layer, a thin film smaller than the refractive index of the crystalline substrate and larger than the refractive index of air is deposited on at least one of the side and bottom of the crystalline substrate. For example, a coating method, an evaporation method, a chemical vapor deposition method, or a sputtering method may be applied. The thin film may be, for example, indium tin oxide (ITO), indium phosphate (Indium Phorphorus Oxide, InPOx), indium arsenic oxide (Indium Arsenic Oxide), glass (glass), sodium chloride (Sodium Chloride, NaCl) , Titanium oxide (TiO 2), quartz (Quartz), or a combination thereof. The glass has a refractive index of about 1.46, about 1.5 of the sodium chloride, about 1.5 of the titanium oxide, and about 1.46 of the quartz. The above deposition methods may be used alone or in combination of two or more. Alternatively, the process of depositing the thin film is not limited thereto, and various other known methods may be applied. FIG. 5B schematically illustrates the formation of the refractive index buffer layer 524 on the side and bottom of the crystalline substrate 522. Although the figure shows that the refractive index buffer layer 524 is formed on both the side surface and the bottom surface of the crystalline substrate 522, the refractive index buffer layer 524 may be formed on either the side surface or the bottom surface.

In another embodiment, in the process of forming the refractive index buffer layer, the deposited thin film may be patterned using a lithography process and an etching process. By the patterning process, the refractive index buffer layer may be formed in a continuous or discontinuous pattern on at least one of the side and bottom of the crystalline substrate. FIG. 5C illustrates the refractive index buffer layer 525 formed in a discontinuous pattern on at least one of the side surface and the bottom surface of the crystalline substrate 522 by the patterning process. Unlike the illustrated example, the refractive index buffer layer 525 may be formed on at least one of the side surfaces and the bottom surface in a continuous pattern.

In another embodiment, in the process of forming the refractive index buffer layer, first, at least one surface area of the side and bottom of the crystalline substrate is melted. The molten surface region is then cooled appropriately to form an amorphous material layer. An amorphous material layer formed when a predetermined surface region of the crystalline substrate is melted serves as the refractive index buffer layer. According to the inventor, the faster the cooling rate of the molten region is, the higher the probability that the amorphous material layer is formed. The high cooling rate results in insufficient diffusion and bonding time for the rearrangement of the members, and consequently the lack of bonding structure in the stoichiometric regular form. Since the bonding structure of the amorphous material layer is not regular compared to the crystalline, it may be an optically small medium. Thus, the amorphous material layer may have a lower refractive index than the crystalline substrate. The process of melting the surface region may be performed using, for example, a laser or a rapid thermal process apparatus.

In one embodiment, in the step of melting the predetermined surface area, at least one of the side and bottom of the crystalline substrate, such that the amorphous material layer is formed as a film covering at least one or more of the side and bottom of the crystalline substrate. At least one region may be irradiated with the laser, or the rapid heat treatment process may be performed. The cooling rate is controlled to form the amorphous material layer. As shown in FIG. 6B, the refractive index buffer layer 624, which is an amorphous material layer, is formed in the form of a thin film over the entire side and bottom surfaces of the crystalline substrate 522.

In another embodiment, in the step of melting the predetermined surface region, at least one or more regions of the side and bottom of the crystalline substrate may be locally melted so that the amorphous material layer is formed as a continuous or discontinuous pattern. . That is, the laser is locally irradiated to a predetermined region of the side surface and the bottom surface of the crystalline substrate 522 or the rapid heat treatment process is performed. The cooling rate is controlled to form a pattern of the amorphous material layer. As shown in FIG. 6C, the refractive index buffer layer 625, which is an amorphous material layer, is formed in the form of a discontinuous pattern.

7 is a flowchart illustrating a method of manufacturing an LED chip according to another embodiment of the present application. Referring to FIG. 7, in block 710, a plurality of LED devices are formed on a crystalline wafer. As described above with reference to FIG. 1A, the plurality of LED devices may be formed on the crystalline wafer through an epi wafer manufacturing process. Specifically, an active layer (not shown), an N-type semiconductor layer (not shown) for providing electrons to the active layer, and a P-type semiconductor layer (not shown) for providing holes in the active layer may be formed on the crystalline wafer. The N-type electrode and the P-type electrode (not shown) may be formed to be electrically connected to the N-type semiconductor layer and the P-type semiconductor layer.

In block 720, a transmissive refractive index buffer layer is formed on the bottom surface of the crystalline wafer. Unlike the embodiment described above with reference to the flowchart of FIG. 4, in the present embodiment, the refractive index buffer layer is formed on the bottom surface of the crystalline wafer while a plurality of LED elements are arranged on the crystalline wafer.

In an embodiment, the process of forming the refractive index buffer layer may be performed by depositing a thin film on the bottom surface of the crystalline wafer that is smaller than the refractive index of the crystalline substrate and larger than the refractive index of air. As the deposition process, for example, a coating method, an evaporation method, a chemical vapor deposition method, or a sputtering method may be applied. The thin film may be, for example, indium tin oxide (ITO), indium phosphate (Indium Phorphorus Oxide, InPOx), indium arsenic oxide (Indium Arsenic Oxide), glass (glass), sodium chloride (Sodium Chloride, NaCl) , Titanium oxide (TiO 2), quartz (Quartz) or a combination thereof. The glass has a refractive index of about 1.46, about 1.5 of the sodium chloride, about 1.5 of the titanium oxide, and about 1.46 of the quartz. The deposition process described above may be used alone or in combination of two or more. Alternatively, the process of depositing the thin film is not limited thereto, and various other known methods may be applied.

In another embodiment, in the process of forming the refractive index buffer layer, the deposited thin film may be patterned using a lithography process and an etching process. By the patterning process, the refractive index buffer layer may be formed in a continuous or discontinuous pattern on the bottom surface of the crystalline wafer.

In another embodiment, in the step of forming the refractive index buffer layer, first, the surface area of the bottom surface of the crystalline wafer is melted. The molten surface region is then cooled appropriately to form an amorphous material layer. An amorphous material layer formed when a predetermined surface area of the bottom of the crystalline wafer is melted serves as the refractive index buffer layer. According to the inventor, the faster the cooling rate of the molten region is, the higher the probability that the amorphous material layer is formed. The high cooling rate results in insufficient diffusion and bonding time for rearrangement of the members, and consequently the lack of binding structure in the stoichiometric regular form. Since the bonding structure of the amorphous material layer is not regular compared to the crystalline, it may be an optically small medium. Therefore, the amorphous material layer may have a lower refractive index than the crystalline wafer. The process of melting the surface region may be performed using, for example, a laser or a rapid thermal process apparatus.

In one embodiment, in the step of melting the predetermined surface area, the laser is irradiated to the area of the bottom of the crystalline wafer or the rapid thermal treatment so that the layer of amorphous material is formed as a film covering the bottom of the crystalline wafer. The process can be carried out. The cooling rate is controlled to form the amorphous material layer.

In another embodiment, in the step of melting the predetermined surface region, at least one or more regions of the side and bottom of the crystalline substrate may be locally melted so that the amorphous material layer is formed as a continuous or discontinuous pattern. .

In block 730, the crystalline wafer having the refractive index buffer layer formed on the bottom surface is cut, and a plurality of LED elements are disposed on the crystalline substrates separated from each other. The cutting of the crystalline wafer may include, for example, a method of mechanically cutting using a diamond saw or a diamond pencil, a method of cutting by irradiating a laser, and various other known methods may be applied.

As described above, the LED chip according to the embodiment presented in the present application is manufactured to have a refractive index buffer layer positioned on at least one or more of the side and bottom of the crystalline substrate and is transparent. As a result, light emitted from the LED device and traveling inside the crystalline substrate may be increased to be emitted to the outside air through the side or bottom of the crystalline substrate. In addition, the refractive index buffer layer forming process may be performed using a method of depositing a thin film smaller than the refractive index of the crystalline substrate and larger than the refractive index of air or a method of patterning the deposited thin film. Alternatively, the refractive index buffer layer forming process may be performed by melting and cooling a predetermined surface region of the crystalline substrate using a laser or a rapid thermal processing apparatus. The above-described method has an advantage that it can be performed using the semiconductor process applied in the chip manufacturing process as it is.

Table 1 is a table comparing the light output of the LED chip with or without the refractive index buffer layer according to an embodiment of the present application. LED chip according to an embodiment of the present application includes a refractive index buffer layer on the side of the crystalline substrate. The LED chip with the refractive index buffer layer and the LED chip without the refractive index buffer layer were each manufactured in the same package and then tested for light output. The emission wavelength of the LED chip is a blue wavelength of about 450 nm.

Serial number Index buffer layer
Presence Emission wavelength (nm) Optical power (mW) One X 445.55 22.02 2 X 446.11 22.02 3 X 450.56 22.04 4 X 452.90 22.22 5 X 453.59 22.71 6 X 448.96 22.41 7 X 448.80 22.46 8 O 449.16 23.35 9 O 452.32 22.70 10 O 445.69 23.43 11 O 446.28 23.47 12 O 450.23 22.86 13 O 451.96 23.10 14 O 450.42 23.39 15 O 450.15 23.41 16 O 450.25 23.41 17 O 449.02 23.19

Referring to Table 1, the LED chips of the present application including the refractive index buffer layer are compared when comparing the light outputs of the LED chips of the serial numbers 1 to 7 without the refractive index buffer layer and the LED chips of the serial numbers 8 to 17 with the refractive index buffer layer. It can be seen that about 4% to 6% improved light output.

From the above, various embodiments of the present disclosure have been described for purposes of illustration, and it will be understood that various modifications are possible without departing from the scope and spirit of the present disclosure. And the various embodiments disclosed are not intended to limit the present disclosure, the true spirit and scope will be presented from the following claims.

100: crystalline wafer, 110: LED element, 120: LED chip, 122: crystalline substrate
210, 212: LED element, 220, 230: LED chip, 222: crystalline substrate, 224, 234: refractive index buffer layer,
330: LED chip, 510: LED element, 522: crystalline substrate, 524, 525, 624, 625: refractive index buffer layer.

Claims (21)

In the LED chip,
Crystalline substrates;
An LED element disposed on the crystalline substrate; And
A refractive index buffer layer disposed on at least one of the side and bottom of the crystalline substrate and translucent,
The refractive index buffer layer is smaller than the refractive index of the crystalline substrate, has a refractive index greater than the refractive index of the air, and the LED chip to perform the function of improving the emission to the outside of the crystalline substrate for the light generated by the LED element.
delete The method according to claim 1,
The refractive index buffer layer is indium tin oxide (ITO), indium phosphate (Indium Phorphorus Oxide, InPOx), Indium Arsenic Oxide (glass), Sodium Chloride (NaCl), Titanium oxide LED chip comprising at least one selected from the group consisting of (titanium oxide, TiO 2) and quartz. The method according to claim 1,
The refractive index buffer layer is an LED chip that covers at least one of the side and bottom of the crystalline substrate (layer). The method according to claim 1,
And the refractive index buffer layer is positioned in a continuous or discontinuous pattern on at least one of the side and the bottom of the crystalline substrate. The method according to claim 1,
The crystalline substrate is a single crystal sapphire, the refractive index buffer layer is an amorphous sapphire LED chip. In the manufacturing method of the LED chip,
(a) forming a light emitting structure in which the LED element is disposed on the crystalline substrate; And
(b) forming at least one of the side surfaces and the bottom surface of the crystalline substrate, the refractive index buffer layer having a refractive index smaller than the refractive index of the crystalline substrate and larger than the refractive index of air and translucent;
Method of manufacturing LED chips.
delete The method of claim 7, wherein
(B) the step of depositing a thin film on the at least one of the side and bottom of the crystalline substrate, the thin film having a refractive index less than the refractive index of the crystalline substrate and greater than the refractive index of air. 10. The method of claim 9,
(B) the process further comprises the step of patterning the deposited thin film using a lithography process and an etching process. The method of claim 9 or 10,
The thin film may be formed of indium tin oxide (ITO), indium phosphate (Indium Phorphorus Oxide, InPOx), indium arsenic oxide (Indium Arsenic Oxide), glass (glass), sodium chloride (NaCl), titanium oxide ( Titanium oxide, TiO 2) and a method of manufacturing an LED chip comprising at least one selected from the group consisting of quartz (Quartz). The method of claim 9 or 10,
The process of depositing the thin film may include at least one of coating, evaporation, chemical vapor deposition, and sputtering. The method of claim 7, wherein
(b) the process
and (b1) melting at least one or more surface regions of the side and bottom of the crystalline substrate to form an amorphous material layer from the molten surface region. The method of claim 13,
(b1) the step of melting the at least one or more of the surface area of the side and the bottom of the crystalline substrate, such that the layer of the amorphous material, to form a layer covering at least one of the side and the bottom of the crystalline substrate; Method of manufacturing the chip. The method of claim 13,
(b1) The manufacturing method of the LED chip which locally melts at least one or more surface areas of the side and bottom of the crystalline substrate so that a continuous or discontinuous pattern is formed as the amorphous material layer. The method according to any one of claims 13 to 15,
The step of melting the surface area is a method of manufacturing an LED chip using a laser or a rapid thermal process (Rapid Thermal Process) device. The method according to any one of claims 13 to 15,
The crystalline substrate is made of a single crystal sapphire, and the amorphous material layer is formed of amorphous sapphire LED chip manufacturing method. In the manufacturing method of the LED chip,
(a) forming a plurality of LED elements on the crystalline wafer;
(b) forming a transmissive refractive index buffer layer on the bottom surface of the crystalline wafer using a thin film deposited with a refractive index smaller than the refractive index of the crystalline wafer and larger than the refractive index of air; And
(c) cutting the crystalline wafer and disposing each of the plurality of LED elements on a crystalline substrate separated from each other.
delete The method of claim 18,
(b) the process
The method of manufacturing an LED chip further comprises the step of patterning the deposited thin film using a lithography process and an etching process. The method of claim 18,
(b) the process
Melting a surface region of the bottom surface of the crystalline wafer to form an amorphous material layer from the molten surface region.

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