KR20120047714A - Led and manufacturing method thereof - Google Patents

Led and manufacturing method thereof Download PDF

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KR20120047714A
KR20120047714A KR1020100109434A KR20100109434A KR20120047714A KR 20120047714 A KR20120047714 A KR 20120047714A KR 1020100109434 A KR1020100109434 A KR 1020100109434A KR 20100109434 A KR20100109434 A KR 20100109434A KR 20120047714 A KR20120047714 A KR 20120047714A
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layer
light emitting
emitting diode
light
thin film
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KR1020100109434A
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Korean (ko)
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박윤석
정다운
한예지
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엘지디스플레이 주식회사
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    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/005—Processes
    • H01L33/0062—Processes for devices with an active region comprising only III-V compounds
    • H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/04—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction
    • H01L33/06—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a quantum effect structure or superlattice, e.g. tunnel junction within the light emitting region, e.g. quantum confinement structure or tunnel barrier
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/12—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a stress relaxation structure, e.g. buffer layer
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/40—Materials therefor
    • H01L33/42—Transparent materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/44—Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0025—Processes relating to coatings

Abstract

The present invention discloses a light emitting diode device and a method of manufacturing the same. More particularly, the present invention relates to a light emitting diode device and a method of manufacturing the same, which reduce light extraction efficiency according to different refractive indices of respective material layers in a semiconductor light emitting diode device (LED) using a group III nitride compound.
A light emitting diode device according to a preferred embodiment of the present invention includes a substrate, a lower layer formed on the substrate and having a first electrode in a partial region, an active layer formed on the upper layer, an upper layer, and an upper layer formed on the substrate. And a light diffusion layer formed on at least one of the lower portion of the substrate or the upper portion of the transparent electrode layer to increase the directivity angle of the incident light.
Accordingly, the present invention diffuses the light emitted from the light emitting diode elements through a plurality of thin film layers formed on the light emitting diode elements and diffuses the light emitted in the vertical direction to the panel, thereby providing a quality of the screen displayed by the liquid crystal display device. Has the effect of improving.

Description

Light Emitting Diode Device and Manufacturing Method Thereof {LED AND MANUFACTURING METHOD THEREOF}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting diode device, and more particularly, to a light emitting diode device having improved light extraction efficiency according to different refractive indices of respective material layers in a semiconductor light emitting diode device (LED) using a group III nitride compound and a method of manufacturing the same. It is about.

As is well known, a light emitting diode (LED), which is a semiconductor light emitting device, is a device that emits light energy of various wavelengths by applying an electrical signal using characteristics of a compound semiconductor. The commercially available light emitting diode device is a compound semiconductor process using a p-type semiconductor (Group III) having a large number of holes and an n-type semiconductor (Group V) having a large number of electrons.

The above-described light emitting diode device is a high-efficiency low-power device, which has the advantages of miniaturization, thinning, and lightening, and does not require long life, preheating time, and very fast turn on / off speed, and thus, lighting of existing incandescent lamps, fluorescent lamps, etc. It is attracting more attention as it replaces the device and is utilized in a backlight module of a large area liquid crystal display (LCD).

1 is a view showing the structure of a conventional group III nitride based light emitting diode device.

As shown in the drawing, a conventional group III nitride-based light emitting diode device forms a buffer layer 15 for buffering on a substrate 10, and is formed of an n-type nitride-based semiconductor on the buffer layer 15. The lower layer 20 is formed. Further, the active layer 25 made of a nitride semiconductor and the top layer 40 made of a p-type nitride semiconductor are sequentially grown on the lower layer 20. Subsequently, after forming the transparent electrode layer 42 which makes an ohmic contact with the upper layer 40, an etching process for exposing the lower layer 20 is performed, and contact pads 24 and 44 for electrical connection to the outside are formed. It is manufactured to have the structure shown. According to this structure, the LED chip emits light according to the combination of electrons and holes in the active layer 25 by the voltage applied to the contact pads 24 and 44.

In the material layers such as sapphire substrate, epitaxial and epoxy, constituting the light emitting diode device having the above-mentioned structure, most of the light components are not vertically but vertically due to the difference in refractive index of the interlayer materials. Is formed. FIG. 2 is a graph showing a direction angle and a distribution of light emitted from an active layer of a conventional light emitting diode device. As shown in the related art, a light emitting angle of light emitted from an active layer is within a predetermined range. O a convergence (a), and also has a characteristic that the distribution of light is concentrated in the vertical direction (h) components rather than the horizontal direction (b) (b).

Accordingly, as shown in FIG. 3, when the above-described light emitting diode element is used for the direct type backlight unit a and the edge type backlight unit b included in the liquid crystal display device. Since the distribution of light emitted from the light emitting diode elements l 1 and l 2 is concentrated in the vertical direction, the regions f1 and f2 corresponding to the positions where the light emitting diode elements are arranged on the screen when the liquid crystal display is driven are displayed. A phenomenon that looks brighter than the area occurs. Such a phenomenon cannot be removed only by the optical compensation sheet provided in the backlight unit, and thus it is difficult to realize a uniform surface light source.

This causes a decrease in the quality of the entire image displayed by the liquid crystal display.

The present invention has been made to solve the above-described problems, by scattering the direction of the light emitted through the light emitting diode elements used in the backlight unit of the conventional liquid crystal display device, which can implement a uniform surface light source and Its purpose is to provide a method for producing the same.

In order to achieve the above object, a light emitting diode device according to a preferred embodiment of the present invention, the light emitting structure for emitting light; And a light diffusion layer formed on at least one of a lower portion and an upper portion of the light emitting structure to increase a direction angle of light emitted from the light emitting structure, wherein the light diffusion layer includes a plurality of thin film layers having different refractive indices. It is done.

The light emitting structure, the substrate; A lower layer formed on the substrate and having a first electrode in one region; An active layer formed on the lower layer to emit light; An upper layer formed on the active layer; And a transparent electrode layer formed on the upper layer and having a second electrode.

A buffer layer is further provided between the substrate and the lower layer.

The plurality of thin film layers is characterized in that the refractive index of at least the lowermost thin film layer is higher than the refractive index of the uppermost thin film layer.

The lowermost thin film layer is characterized in that the refractive index is at least lower than the light emitting structure.

The plurality of thin film layers is characterized in that each of the same material having a different thickness.

The plurality of thin film layers may be one of silicon oxide (SiO) or silicon nitride (SiN).

The substrate is composed of one of sapphire, silicon (si), silicon carbide (SiC), gallium arsenide (GaAs) and zinc oxide (ZnO), and the lower layer is an n-type gallium nitride (GaN) layer, An undoped n-type gallium nitride (GaN) layer below the gallium nitride layer, the upper layer includes p-type gallium nitride (GaN), and the transparent electrode layer is indium tin oxide (Indium Tin) Oxide, ITO) or Indium Zinc Oxide (IZO), and the active layer is characterized in that the multi-quantum well (MQW) structure.

It characterized in that it further comprises a reflective layer formed on the lower portion of the substrate or the transparent electrode layer.

In order to achieve the above object, a method of manufacturing a light emitting diode device according to a preferred embodiment of the present invention, forming a light emitting structure for emitting light; And forming a light diffusion layer on at least one of the lower portion and the upper portion of the light emitting structure to increase a direction angle of light emitted from the light emitting structure, wherein the light diffusion layer includes a plurality of thin film layers having different refractive indices. It is characterized by.

The forming of the light emitting structure may include forming a substrate; Forming a lower layer having a first electrode on one region of the substrate; Forming an active layer emitting light on top of the lower layer; Forming an upper layer on top of the active layer; And forming a transparent electrode layer having a second electrode on the upper layer.

And forming a buffer layer over the substrate, between forming the substrate and forming the lower layer.

The plurality of thin film layers is characterized in that the refractive index of at least the lowermost thin film layer is higher than the refractive index of the uppermost thin film layer.

The lowermost thin film layer is characterized in that the refractive index is at least lower than the light emitting structure.

The plurality of thin film layers is characterized in that each of the same material having a different thickness.

The plurality of thin film layers may be one of silicon oxide (SiO) or silicon nitride (SiN).

The substrate is composed of one of sapphire, silicon (si), silicon carbide (SiC), gallium arsenide (GaAs) and zinc oxide (ZnO), and the lower layer is an n-type gallium nitride (GaN) layer and the An undoped n-type gallium nitride (GaN) layer below the gallium nitride layer, the upper layer includes p-type gallium nitride (GaN), and the transparent electrode layer is indium tin oxide. , ITO) or indium zinc oxide (IZO), wherein the active layer is characterized in that the multi-quantum well (MQW) structure.

After the forming of the light emitting structure, the method may further include forming a reflective layer at a position opposite to the light diffusion layer.

According to a preferred embodiment of the present invention, through the plurality of thin film layers formed on the light emitting diode element can increase the light in the horizontal direction by increasing the angle of refraction of the light emitted by the light emitting diode element, thereby the light of the light emitting diode element There is an effect of increasing the orientation angle. Therefore, it is possible to improve the screen quality of the liquid crystal display device having the backlight unit composed of the light emitting diode elements of the present invention.

1 is a view showing the structure of a conventional group III nitride based light emitting diode device.
FIG. 2 is a view schematically showing a direction angle and distribution of light emitted from an active layer of a conventional light emitting diode device.
FIG. 3 is a diagram for describing image quality deterioration occurring in a liquid crystal display device having a conventional LED device.
4 is a view showing the structure of a light emitting diode device according to a first embodiment of the present invention.
5 is a cross-sectional view of a portion of a light emitting device according to an embodiment of the present invention.
6 is a graph illustrating a direction angle and a distribution of light emitted from a light emitting diode device according to an exemplary embodiment of the present invention.
7 is a flowchart illustrating a method of manufacturing a light emitting diode device according to an embodiment of the present invention.
8 is a cross-sectional view of a light emitting diode device according to a second exemplary embodiment of the present invention.

Hereinafter, a light emitting diode device and a method of manufacturing the same according to a preferred embodiment of the present invention will be described with reference to the drawings.

The growth method of the substrate and each layer described below is not only a conventional metal organic chemical vapor deposition (MOCVD) method but also a molecular beam epitaxy (MBE), a plasma enhanced chemical vapor deposition (PECVD), and a vapor phase (VPE) Epitaxy) can be implemented.

4 is a view showing the structure of a light emitting diode device according to a first embodiment of the present invention.

As shown, the LED device of the present invention includes a substrate 100, a buffer layer 150, a lower layer 200 and 210, an n-type semiconductor pad 240, an active layer 300, an upper layer 400, and a transparent electrode layer ( 420, a light emitting structure including the p-type semiconductor pad 440, the above-described transparent electrode layer 320, and the p-type semiconductor pad 440, and a light diffusion layer 500 for increasing a directing angle of light emitted from the light emitting structure. It includes.

More specifically, the substrate 100 is to grow a gallium nitride (GaN) thin film, the gallium nitride (GaN) substrate ideal for such a nitride-based LED as the substrate 100, but gallium nitride (GaN) The single crystal substrate using is difficult to manufacture and has a disadvantage of high unit cost. Accordingly, sapphire, silicon (si), silicon carbide (SiC), gallium arsenide (GaAs), zinc oxide (ZnO), and the like, which are relatively easy to obtain and low in cost, may be used.

In addition, a rear surface of the substrate 100 may further include a reflecting plate (not shown) for increasing light efficiency, and the reflecting plate may be formed by a method such as sputtering or evaporation.

The buffer layer 150 is grown to complement the characteristics of the substrate 100. The buffer layer 150 includes lower layers 200 and 210 including n-type GaN as an epi layer on the sapphire or silicon carbide (SiC) substrate. ) Is directly grown between the substrate 100 and the lower layers 200 and 210 to overcome this problem because it is difficult to manufacture a high quality device by lattice mismatch.

The lower layers 200 and 210 serve to supply electrons to the active layer 300 to be described later in the light emitting diode device of the present invention, and are undoped as a base layer of a gallium nitride (GaN) layer on the buffer layer 150. The gallium nitride (GaN) layer 210 is grown, and the gallium nitride (GaN) semiconductor layer 200 is grown by doping n-type impurities. Si may be used as the n-type impurity, and a semiconductor pad to be described later is formed in a portion of the gallium nitride (GaN) semiconductor layer 200.

The n-type semiconductor pad 240 is for wire bonding when the LED package is mounted in the LED package after the chip process. The n-type semiconductor pad 240 is formed in a portion where the aforementioned GaN layer 210 is etched.

The active layer 300 serves to convert excess energy into light by recombining electrons and holes supplied from the n-type gallium nitride (GaN) layer 200 and the p-type gallium nitride (GaN) layer described later. The active layer 300 may have a conventional well structure (Quantum Well, QW) or a multiple quantum well structure (MQW) in order to increase efficiency, and by controlling the composition and thickness of the well layer and the barrier layer, Make sure you get the wavelength of the band.

The upper layer 400 is composed of p-type gallium nitride (GaN) to provide holes to the active layer described above. Mg may be used as a doping material for the p-type gallium nitride (GaN) of the upper layer 400.

The transparent electrode layer 420 is formed for ohmic contact on the upper layer 400 and the p-type semiconductor pad for wire bonding. The p-type gallium nitride (GaN) of the upper layer 400 described above has a high resistance and a current that is not sufficiently diffused in the layer. Accordingly, the transparent electrode layer 420 has an area for uniformly flowing current to the entire surface of the device. It should be configured the same as the upper layer 400. The transparent electrode layer 420 is preferably formed of a transparent conductive oxide layer such as an indium tin oxide (ITO), a cadmium tin oxide (CTO), or the like, which is a transparent electrode material of metal.

The p-type semiconductor pad 440 is for electrically connecting the upper layer to the package through wire bonding, and is etched to a predetermined depth from the upper portion of the transparent electrode layer 420 onto the n-type gallium nitride (GaN) layer 200 described above. The n-type gallium nitride (GaN) layer 200 is exposed and then formed together with the n-type semiconductor pad 240. In this case, as the etching method, a dry etching method may be applied.

The light diffusion layer 500 is formed on the entire surface of the above-described transparent electrode layer 420 and has a structure in which a plurality of thin films having different refractive indices are stacked.

In addition, the light diffusion layer 500 has a portion in which a portion of the p-type semiconductor pad 440 is removed to electrically connect the transparent electrode layer 420 and the p-type semiconductor pad 440.

5 is a cross-sectional view of a portion of a light emitting device according to an embodiment of the present invention.

As shown, the light emitting device of the present invention is the n-type GaN layer 200, the active layer 300 formed on the n-type GaN layer 200, the p-type GaN layer 400 formed on the active layer 300 , a transparent electrode layer 420 formed on the p-type GaN layer 400, a p-type semiconductor pad 440 electrically connected to the transparent electrode layer 420, and a light diffusion layer formed on the transparent electrode layer 420 ( 500).

Here, the light diffusion layer 500 is composed of at least one thin film layer as part of the enlarged, each thin film has a different refractive index (n 1 , n 2 , n 3 ). In particular, the thin film layers are characterized by having a relatively low refractive index from the bottom to the top (n 1 <n 2 <n 3 ).

Specifically, the refractive index of the lowermost thin film is higher than the refractive index of the thin film formed on the uppermost thin film (n 2 <n 3 ). The refractive index of the thin film formed on the top of the bottom thin film is higher than that of the top thin film (n 1 <n 2 ).

Light has the property of changing the direction of travel at the interface of a medium as it progresses from one medium to another, which is Snell's law

Figure pat00001

As a result, the light propagating from the medium having the large refractive index to the medium has a large refractive angle.

For example, when the refractive index in air is 1, the light diffusion layer 500 sequentially n 1 from the upper thin film layer. <= 1.4, n 2 <= 1.6, n 3 It may have a value of <= 1.8. In addition, the refractive index n 3 of the thin film layer disposed at the bottom of the light diffusion layer 500 should be at least smaller than the refractive index of the transparent electrode layer 420 formed under the light diffusion layer 500.

The aforementioned thin film layers may be formed to have different thicknesses by using different thicknesses of the same material, or may be implemented to have different refractive indices, or may be implemented with different materials having the same thickness, respectively, and are preferably silicon oxide (SiO) or silicon nitride. (SiN) or the like.

Therefore, the vertical component light emitted from the active layer 300 passes through the p-type GaN layer 400 and the transparent electrode layer 420, is scattered as a horizontal component through the light diffusion layer 500, and emitted to the outside.

FIG. 6 is a graph illustrating a direction angle and component distribution of light emitted from a light emitting diode device according to an exemplary embodiment of the present invention. FIG.

As shown, in the conventional light emitting diode device, the directing angle of emitted light converges to 0 ° within a predetermined range (i), but the light emitted by the light emitting diode device of the present invention is scattered in the form of a directing angle of 40 °. Diffuse within (j).

According to the above-described structure, the light emitting diode device of the present invention is horizontally formed by scattering light emitted from the transparent electrode by the light diffusion layer. In other words, in the light emitting diode device of the present invention, when light emitted from the active layer passes through each of the thin film layers of the light diffusing layer shown in FIG. 5, light closer to the vertical direction at the interface of each thin film layer has a larger refractive angle in the horizontal direction. The light in the horizontal direction is increased, thereby increasing the directing angle of the light emitted from the light emitting diode device.

Hereinafter, a method of manufacturing a light emitting diode device according to a preferred embodiment of the present invention will be described with reference to the drawings.

7 is a flowchart illustrating a method of manufacturing a light emitting diode device according to an embodiment of the present invention.

As shown, the method of manufacturing the light emitting diode of the present invention comprises the steps of forming a buffer layer (S100), forming an undoped GaN layer (S110), forming an n-type GaN layer (S120), forming an active layer The step S130, the step of forming a p-type GaN layer (S140), the step of forming a transparent electrode layer (S150), the step of forming a light diffusion layer (S160) and the step of forming a pad (S170).

More specifically, the step of forming a buffer layer (S100) is to form a buffer layer for the growth of the GaN layer by a method such as MOCVD or MBE, in order to grow the GaN layer on the sapphire substrate or silicon carbide substrate It's a step.

The forming of the undoped GaN layer (S110) is a step of forming an undoped GaN layer which is not doped with impurities on the buffer layer.

In the forming of the n-type gallium nitride (GaN) layer (S120), the n-type GaN layer is formed by doping Si, which is an n-type impurity, on the undoped GaN layer.

Forming an active layer (S130) is a step of forming a quantum well (QW) or a multi quantum well (MQW) layer on the n-type GaN layer.

In the forming of the p-type GaN layer (S140), an n-type GaN layer is formed on the active layer, and an n-type GaN layer is formed by doping Mg, which is an impurity.

In the forming of the transparent electrode layer (S150), a transparent electrode layer for ohmic contact of the p-type GaN layer is formed on the entire surface of the upper portion of the p-type GaN layer by using a material such as ITO.

Forming the light diffusion layer (S160) is a step of forming a thin film layer on the transparent electrode layer. Here, the multiple thin film layers are composed of a plurality of thin film layers, and each of the plurality of thin film layers has a different refractive index. In addition, the plurality of thin film layers is characterized in that the value of the refractive index decreases toward the outside from the contact surface.

In addition, when the light emitting diode device is a flip type rather than a general type, the above-described light diffusion layer may be formed below the substrate rather than the upper portion of the transparent electrode layer, which will be described later.

Thereafter, forming the pad (S170) includes forming a first semiconductor pad electrically connected to the transparent electrode layer and a second semiconductor pad electrically connected to the n-type GaN layer. In this step, a portion of the light diffusion layer is removed to expose a portion of the transparent electrode layer, and a portion of the light diffusion layer, the transparent electrode layer, the p-type GaN layer, and the active layer is exposed to expose a portion of the n-type GaN layer. Etch to a predetermined height of the GaN layer. Thereafter, the first and the first semiconductor pads are formed in the exposed regions.

According to the above-described steps, according to the manufacturing method of the light emitting diode device of the present invention, the light diffusion layer is provided on the transparent electrode layer of the light emitting diode device to scatter the vertical component of the emitted light to convert to a horizontal component. Hereinafter, a light emitting diode device according to a second embodiment of the present invention will be described with reference to the drawings. In the following description, for the convenience of description, detailed descriptions of the same parts as in the first embodiment will be omitted.

8 is a cross-sectional view of a light emitting diode device according to a second exemplary embodiment of the present invention. The second embodiment to be described below is a flip chip type light emitting diode device, which has a similar structure to the light emitting diode device according to the first embodiment, but differs in the direction in which light is emitted. As a result, the position of the light diffusion layer formed is different.

In a conventional light emitting diode device, light generated in the active layer travels in an arbitrary direction, is absorbed by the active layer itself, or is reflected by the surface or a pad of the device and part or all of it is returned to the inside of the device. When the total loss of light is added, about 80% or more cannot escape and is dissipated from the inside to be converted into heat. The flip chip method is designed to solve these drawbacks, and is designed to emit light through the transparent substrate, thereby eliminating losses in the pads and other layers, thereby improving light extraction efficiency and improving current spreading.

Referring to the drawings, as described above, the flip chip type light emitting diode device according to the second embodiment is a type in which light emitted from the active layer is emitted in the direction of the substrate rather than in the direction of the transparent electrode layer. A buffer layer 152, an undoped n-type GaN layer 212, an n-type GaN layer 202, an n-type semiconductor pad 242, an active layer 302, and a p-type GaN layer 402 below the substrate 102. , A transparent electrode layer 422, a p-type semiconductor pad 442, and a light diffusion layer 502 formed over the substrate 102. Although not shown, a reflective layer may be further formed below the transparent electrode layer 422.

Here, the light diffusion layer 502 is composed of at least one thin film layer as in the first embodiment, each thin film layer has a different refractive index. In addition, the thin film layers have a lower refractive index than the substrate, and have a relatively low refractive index toward the upper direction of the substrate.

That is, the refractive index of the lowest thin film is higher than the refractive index of the thin film formed on the uppermost thin film (n 2 <n 3 ). The refractive index of the thin film formed on the top of the bottom thin film is higher than that of the top thin film (n 1 <n 2 ).

This is because, according to Equation 1, light propagating from a medium having a large refractive index to a small medium has a large refractive angle. For example, when the refractive index in air is 1, the light diffusion layer 502 is formed from the upper thin film layer. Sequentially n 1 <= 1.4, n 2 <= 1.6, n 3 It may have a value of <= 1.8. In addition, the refractive index n 3 of the thin film layer disposed at the bottom of the light diffusion layer 502 should be at least smaller than the refractive index of the substrate 102 formed under the light diffusion layer 502.

The thin film layers described above may be formed to have different thicknesses by using the same material, and may have different refractive indices, or may be implemented with different materials having the same thickness, respectively. In the same manner as in the first embodiment, silicon oxide (SiO), It is preferably composed of silicon nitride (SiN) or the like.

According to the above-described structure, the light emitting diode device of the present invention scatters the light emitted from the substrate by the light diffusion layer so that the traveling direction is formed horizontally.

In addition, although not shown, a method of manufacturing a light emitting diode device according to the second embodiment of the present invention is also similar to the first embodiment, except that the light diffusion layer is formed on a substrate rather than a transparent electrode layer.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed exemplary embodiments.

100 substrate 150 buffer layer
200, 210: Lower layer 240: n-type semiconductor pad
300: active layer 400: upper layer
420: transparent electrode layer 440: p-type semiconductor pad
500: light diffusion layer

Claims (18)

A light emitting structure that emits light; And,
A light diffusion layer formed on at least one of the lower and upper portions of the light emitting structure to increase a directing angle of light emitted from the light emitting structure,
The light diffusing layer comprises a plurality of thin film layers having different refractive indices
Light emitting diode device. The method of claim 1,
The light emitting structure, the substrate;
A lower layer formed on the substrate and having a first electrode in one region;
An active layer formed on the lower layer to emit light;
An upper layer formed on the active layer; And,
A transparent electrode layer formed on the upper layer and having a second electrode
Light emitting diode device comprising a. The method of claim 2,
A light emitting diode device, further comprising a buffer layer between the substrate and the lower layer. The method of claim 2,
The substrate is composed of one of sapphire, silicon (si), silicon carbide (SiC), gallium arsenide (GaAs) and zinc oxide (ZnO),
The lower layer includes an n-type gallium nitride (GaN) layer and an undoped n-type gallium nitride (GaN) layer below the gallium nitride layer,
The upper layer includes p-type gallium nitride (GaN),
The transparent electrode layer includes one of Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO),
The active layer is a light emitting diode device, characterized in that the multi quantum well (MQW) structure. The method of claim 1,
The plurality of thin film layers, the refractive index of at least the lowermost thin film layer is higher than the refractive index of the uppermost thin film layer. The method of claim 1,
And the lowermost thin film layer has a lower refractive index than at least the light emitting structure. The method of claim 1,
The plurality of thin film layers, the light emitting diode device, characterized in that each of the same material having a different thickness. The method of claim 1,
The thin film layer is a light emitting diode device, characterized in that one of silicon oxide (SiO) or silicon nitride (SiN). The method of claim 1,
The light emitting diode device further comprises a reflective layer formed on the lower portion of the substrate or the upper portion of the transparent electrode layer. In the method of manufacturing a light emitting diode device,
Forming a light emitting structure that emits light; And,
Forming a light diffusion layer on at least one of a lower portion and an upper portion of the light emitting structure to increase a directing angle of light emitted from the light emitting structure,
The light diffusion layer includes a plurality of thin film layers having different refractive indices. The method of claim 10,
Forming the light emitting structure,
Preparing a substrate;
Forming a lower layer having a first electrode on one region of the substrate;
Forming an active layer emitting light on top of the lower layer;
Forming an upper layer on top of the active layer; And,
Forming a transparent electrode layer having a second electrode on the upper layer
Method of manufacturing a light emitting diode device comprising a. The method of claim 11,
Between forming the substrate and forming the lower layer,
The method of manufacturing a light emitting diode device, characterized in that it further comprises the step of forming a buffer layer on top of the substrate. The method of claim 11,
The substrate is composed of one of sapphire, silicon (si), silicon carbide (SiC), gallium arsenide (GaAs) and zinc oxide (ZnO),
The lower layer includes an n-type gallium nitride (GaN) layer and an undoped n-type gallium nitride (GaN) layer below the gallium nitride layer,
The upper layer includes p-type gallium nitride (GaN),
The transparent electrode layer includes one of Indium Tin Oxide (ITO) or Indium Zinc Oxide (IZO),
The active layer is a manufacturing method of a light emitting diode device, characterized in that the multi quantum well (MQW) structure. The method of claim 10,
The plurality of thin film layers have a refractive index of at least the lowermost thin film layer is higher than the refractive index of the uppermost thin film layer. 15. The method of claim 14,
The lowermost thin film layer has a lower refractive index than at least the light emitting structure. The method of claim 10,
The plurality of thin film layers, the method of manufacturing a light emitting diode device, characterized in that each of the same material having a different thickness. The method of claim 10,
The thin film layer is a method of manufacturing a light emitting diode device, characterized in that one of silicon oxide (SiO) or silicon nitride (SiN). The method of claim 10,
And after the forming of the light emitting structure, forming a reflective layer at a position opposite to the light diffusion layer.
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Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150091923A (en) * 2014-02-04 2015-08-12 엘지이노텍 주식회사 Light Emitting Device Package

Cited By (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
KR20150091923A (en) * 2014-02-04 2015-08-12 엘지이노텍 주식회사 Light Emitting Device Package

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