KR20060074390A - Luminescence device and method of manufacturing the same - Google Patents

Abstract

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a light emitting device and a method of manufacturing the same, wherein a substrate, an N-type semiconductor layer formed on the substrate, a P-type semiconductor layer formed on a predetermined region of the N-type semiconductor layer, and the P-type semiconductor layer A first transparent electrode layer formed on the substrate, a P electrode formed on the first transparent electrode layer, and an N electrode formed on the N-type semiconductor layer, wherein the P-type semiconductor layer is formed on a surface of the N-type semiconductor layer on which the P-type semiconductor layer is not formed. A light emitting device having a roughness of and a method of manufacturing the same are provided. As such, by forming the transparent electrode layer on the exposed N-type semiconductor layer of the light emitting device and using it as the N electrode, the light emitting area can be enlarged, the light output can be maximized, and the surface of the N-type semiconductor layer is predetermined. It is possible to improve the quantum efficiency of the light emitting device by forming the unevenness having the roughness of to emit light also in the N-type semiconductor layer.

Light emitting element, transparent electrode, roughness, gallium nitride, N electrode, surface emission

Description

Light emitting device and method of manufacturing the same {Luminescence device and method of manufacturing the same}             

1A to 1D are cross-sectional views illustrating a method of manufacturing a light emitting device according to a conventional process.

2A to 2F are cross-sectional views illustrating a method of manufacturing a light emitting device according to the present invention.

3 is a cross-sectional view of a light emitting device according to another embodiment of the present invention;

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

10, 110: substrate 20: N-GaN layer

30, 130: active layer 40: P-GaN layer

50, 150, 160: transparent electrode 60, 70, 170, 180: electrode

120: N-type semiconductor layer 140: P-type semiconductor layer

155, 157: Photosensitive film pattern 165: N-type metal pad

The present invention relates to a light emitting device and a method of manufacturing the same, and more particularly, to a light emitting device that emits light in an N-type semiconductor layer region.

Conventional light emitting devices sequentially form an N-GaN layer, an active layer and a P-GaN layer on a sapphire substrate. At this time, since the sapphire substrate under the N-GaN layer is an insulator, a portion of the active layer and the P-GaN layer on the N-GaN layer are etched to expose the N-GaN layer and connected to an external power source. In addition, since the resistance component of the P-GaN layer is very large, a transparent electrode was formed to uniformly apply voltage to the upper surface of the P-GaN layer.

1A to 1D are cross-sectional views illustrating a method of manufacturing a light emitting device according to a conventional process.

Referring to FIG. 1A, an N-GaN layer 20, an active layer 30, and a P-GaN layer 40 are sequentially formed on a sapphire (Al 2 O 3) substrate 10.

Referring to FIG. 1B, a portion of the N-GaN layer 20 is exposed by removing a portion of the P-GaN layer 40 and the active layer 30 through a predetermined patterning process. To this end, a photoresist pattern (not shown) is formed on the P-GaN layer 40, and then the P-GaN layer 40 and the active layer 30 are removed through an etching process using the photoresist pattern as an etching mask. In this case, the photoresist pattern is formed in a shape that exposes a region where the N electrode is to be formed. After the etching process, the photoresist pattern is removed.

Referring to FIG. 1C, a transparent electrode 50 is formed on the P-GaN layer 40. To this end, a photoresist pattern for exposing only the upper portion of the P-GaN layer 40 is formed, and then a transparent electrode 50 is formed in the exposed region.

Referring to FIG. 1D, an N electrode 60 is formed on the exposed N-GaN layer 20, and a P electrode 70 is formed on the transparent electrode 50.

Conventional light emitting devices manufactured as described above have very low external quantum efficiency of 10% or less. This is the light generated in the active layer 30 is spontaneous emission without a specific direction. That is, light is emitted in all directions in the plane forming the PN junction. However, since light is actually reflected, scattered, and absorbed by defects between the semiconductor layer itself and the layers, light is emitted to the outside only in the normal direction perpendicular to the semiconductor layer. However, the amount of light emitted in the normal direction is less than the amount of light emitted along the interface of the PN junction. For this reason, the external quantum efficiency of the light emitting device is lowered.

Therefore, in order to solve the above problem, the present invention can perform light emission not only through the P-type semiconductor layer but also through the N-type semiconductor layer, and gives a predetermined roughness on the N-type semiconductor layer, and the transparent electrode thereon. It is an object of the present invention to provide a light emitting device and a method for manufacturing the same, which can increase the external quantum efficiency by forming a.

Forming an N-type semiconductor layer, a P-type semiconductor layer, and a first transparent electrode layer on the substrate according to the present invention, and removing the first transparent electrode layer and the P-type semiconductor layer in a predetermined region to form the N-type semiconductor layer. And forming a second transparent electrode layer on the exposed N-type semiconductor layer and spaced apart from the P-type semiconductor layer and the first transparent electrode layer by a predetermined distance. .

Here, an active layer is formed between the N-type semiconductor layer and the P-type semiconductor layer. The exposing the N-type semiconductor layer may include forming a predetermined photoresist pattern on the first transparent electrode layer and performing a first etching process using the photoresist pattern as an etching mask. Removing a portion of the photoresist pattern and performing a second etching process using the photoresist pattern as an etching mask to expose the N-type semiconductor layer by removing the remaining first transparent electrode layer, the P-type semiconductor layer, and the active layer; And providing a concave-convex surface having a predetermined roughness on the exposed upper surface of the N-type semiconductor layer, and removing the photoresist pattern.

The method may further include forming a P electrode on the first transparent electrode layer and forming an N-type metal pad on the second transparent electrode layer. And forming an N-type metal pad on the N-type semiconductor layer after forming the P electrode on the first transparent electrode layer and exposing the N-type semiconductor layer.

Further, according to the present invention, a substrate, an N-type semiconductor layer formed on the substrate, a P-type semiconductor layer formed on a predetermined region of the N-type semiconductor layer, and a first transparent electrode layer formed on the P-type semiconductor layer And a P electrode formed on the first transparent electrode layer and an N electrode formed on the N-type semiconductor layer and including a second transparent electrode layer.

At this time, the surface of the N-type semiconductor layer in which the P-type semiconductor layer is not formed has a predetermined roughness. And an active layer formed under the P-type semiconductor layer.

Here, the N electrode includes a second transparent electrode layer formed on the N-type semiconductor layer and a metal pad formed on a predetermined region of the second transparent electrode layer. In addition, the N electrode includes a metal pad formed on a predetermined region of the N type semiconductor layer and a second transparent electrode layer formed on the N type semiconductor layer including the metal pad.

Hereinafter, with reference to the accompanying drawings will be described an embodiment of the present invention in more detail. However, the present invention is not limited to the embodiments disclosed below, but will be implemented in various forms, and only the embodiments are intended to complete the disclosure of the present invention, and to those skilled in the art to fully understand the scope of the invention. It is provided to inform you. Like numbers refer to like elements in the figures.

2A to 2F are cross-sectional views illustrating a method of manufacturing a light emitting device according to the present invention.

Referring to FIG. 2A, the N-type semiconductor layer 120, the active layer 130, the P-type semiconductor layer 140, and the first transparent electrode layer 150 are sequentially formed on the sapphire substrate 110.

In this case, at least one of SiC, ZnO, Si, GaAs, GaP, LiAl 2 O 3, BN, AlN, and GaN may be used instead of the sapphire substrate 110. In addition, a buffer layer (not shown) which serves as a buffer when the N-type semiconductor layer 120 is formed on the substrate 110 may be further formed.

The N-type semiconductor layer 120 preferably uses a gallium nitride (GaN) film in which N-type impurities are implanted, and is not limited thereto. A material layer having various semiconductor properties may be used. In this embodiment, an N-type semiconductor layer 120 including an N _- type Al _x Ga _1-x N (0 ≦ _x ≦ 1) film is formed.

In addition, the P-type semiconductor layer 140 also uses a gallium nitride film into which P-type impurities are implanted. In this embodiment, a P-type semiconductor layer 140 including a P _- type Al _x Ga _1-x N (0≤x≤1) film is formed. In addition, an InGaN film may be used as the semiconductor layer film. In addition, the N-type semiconductor layer 120 and the P-type semiconductor layer 140 may be formed of a multilayer film. In the above, Si is used as the N-type impurity, Zn is used when InGaAlP is used as the P-type impurity, and Mg is used in the case of nitride.

As the active layer 13, a multilayer film in which a quantum well layer and a barrier layer are repeatedly formed on an N-type Al _x Ga _1-x N (0≤x≤1) film is used. As the barrier layer and the well layer, binary compounds such as GaN, InN, and AlN may be used, and ternary compounds In _x Ga _1-x N (0 ≦ _x ≦ ₁ ) and Al _x Ga _1-x N (0 ≤ _x ≤ 1) and the like, and a quaternary compound Al _x In _y Ga _1-xy N (0 ≦ x + y ≦ 1) may be used. Of course, the N-type semiconductor layer 120 and the P-type semiconductor layer 140 may be formed by implanting predetermined impurities into the two- to four-membered compounds. At this time, the composition and thickness of the well layer and the barrier layer may be controlled to obtain light having a target wavelength.

In addition, various material films including indium tin oxide (ITO) are used as the first transparent electrode layer 150. Preferably, a material having a transparency of 50 to 100% is used as the first transparent electrode layer 150.

The above-described material layers can be deposited and grown in various ways including metal organic chemical vapor deposition (MOCVD), molecular beam growth (MBE), hydride vapor phase epitaxy (HVPE), and the like. Is formed through the method.

2B and 2C, a portion of the N-type semiconductor layer 120 is exposed by removing a portion of the first transparent electrode layer 150, the P-type semiconductor layer 140, and the active layer 130. Unevenness having a predetermined roughness is formed on the surface of the type semiconductor layer 120. The roughness Ra of the unevenness of the N-type semiconductor layer 120 is preferably 50 to 50000 Pa.

To this end, first, a photosensitive film is coated on the first transparent electrode layer 150, and then a first photosensitive film pattern 155 is formed through a photolithography process using a mask. In this case, the first photoresist pattern 155 may be formed in a shape that opens an area where the N-type electrode is to be formed and shields the remaining area. That is, as shown in the figure, it is preferable to form so as to open both regions of the P-type semiconductor layer 140. Although not shown, when the first photoresist layer pattern 155 is viewed from the top, the photosensitive film pattern 155 is slightly exposed around the P-type semiconductor layer 140, and has a predetermined width (area) at one vertex region of the rectangular light emitting device. The area with is open.

Thereafter, a part of the exposed first transparent electrode layer 150 is removed by performing a first etching process using the first photoresist pattern 155 as an etching mask. At this time, the thickness of the first transparent electrode layer 150 remaining without being removed during the first etching process is 1 to 500 kPa. When the first transparent electrode layer 150, the P-type semiconductor layer 140, and the active layer 130 that are remaining through the second etching process are removed continuously to expose the N-type semiconductor layer 120, the exposed N-type Certain unevenness is formed on the surface of the semiconductor layer 120.

It is preferable that the first etching process uses a wet etching method and the second etching process uses a dry etching method. That is, the first transparent electrode layer 150, the P-type semiconductor layer 140, and the active layer 130 remaining through dry etching without removing the entirety of the first transparent electrode layer 150 through wet etching are removed. In this case, the surface of the N-type semiconductor layer 120 is roughened. This causes the first transparent electrode layer 150 to act as a barrier to some extent during dry etching, so that the lower layer is not etched smoothly, and the surface thereof has roughness, such as irregularities.

The light output can be further improved by adding a reactive gas to reduce the condition of the rough surface on which the unevenness is formed. At this time, argon (Ar) gas is used as the reactive gas. In other words. Plasma etching, which is physical etching using ionization energy, is performed.

A portion of the N-type semiconductor layer 120 may also be etched together in the second etching process. As described above, a phenomenon in which light is emitted from the N-type semiconductor layer 120 by giving a predetermined uneven surface to the exposed surface of the N-type semiconductor layer 120 of the light emitting device can be seen. It can be improved by 40 to 70%.

2D and 2E, after removing the first photoresist pattern 155, a predetermined cleaning process is performed. Thereafter, the second transparent electrode layer 160 is formed in a predetermined region of the exposed N-type semiconductor layer 120.

To this end, a photoresist film is coated on the entire structure, and then a photolithography process using a mask is performed to form a second photoresist pattern 157 exposing a portion of the N-type semiconductor layer 120. The second photoresist layer pattern 157 is formed to expose all regions of the exposed N-type semiconductor layer 120 except for the region adjacent to the active layer 130. Of course, the present invention is not limited thereto, and the exposed region of the N-type semiconductor layer 120 is exposed, but the active layer 130, the P-type semiconductor layer 140, and the first transparent electrode layer 150 are not exposed. That is, as shown in FIG. 2D, the second photoresist layer pattern 157 is formed to surround the active layer 130, the P-type semiconductor layer 140, and the first transparent electrode layer 150.

Thereafter, a second transparent electrode layer 160 is formed on the N-type semiconductor layer 120 exposed by the second photoresist pattern 157. In this case, the second transparent electrode layer 160 uses the same material layer as the first transparent electrode layer 150 described above. A predetermined strip process is performed to remove the second photoresist pattern 157.

In this case, the second photosensitive film pattern 157 may be formed without removing the first photosensitive film pattern 155. In addition, various material films that may perform a separate barrier function instead of the photoresist pattern may be used instead of the photoresist pattern.

Referring to FIG. 2F, a P electrode 180 is formed in a predetermined region on the first transparent electrode layer 150, and an N-type metal pad 165 is formed in a predetermined region on the second transparent electrode 160 to form an N electrode ( 170).                     

To this end, a mask pattern for forming an electrode is formed on the entire structure. The mask pattern exposes a portion of the first transparent electrode layer 150 formed on the P-type semiconductor layer 130, and exposes a portion of the second transparent electrode layer 160 formed on the N-type semiconductor layer 120. Of course, the mask pattern may expose the entirety of the first transparent electrode layer 150 and the entirety of the second transparent electrode layer 160. Subsequently, a predetermined metal layer is formed on the entire structure, and then the P electrode 180 is formed by removing the metal layer and the mask pattern in a region except the upper portions of the first and second transparent electrode layers 150 and 160 that are open. 2, an N electrode 170 composed of a transparent electrode layer 160 and an N-type metal pad 165 is formed. Of course, the N electrode 170 and the P electrode 180 may be formed through various metal layer deposition methods.

In the present invention, the second transparent electrode layer 160 formed on the N-type semiconductor layer 120 may be used as the N electrode 170. That is, the N-GaN layer used as the N-type semiconductor layer 120 is N type, and the ITO used as the second transparent electrode 160 is also N type. Since ITO is not only excellent in electrical conductivity, but also excellent in refractive index and light transmittance, it can serve as an N-electrode metal. In other words, ITO is more efficient than conventional N metal. In addition, the refractive index n of the ITO is 1.9 to 2.0.

3 is a cross-sectional view of a light emitting device according to another embodiment of the present invention.

Referring to FIG. 3, in the light emitting device according to another embodiment of the present invention, an N-type metal pad 165 is formed on the N-type semiconductor layer 120, and then a second transparent electrode layer 160 is formed thereon. An N electrode 170 is formed.                     

That is, a buffer layer (not shown), an N-type semiconductor layer 120, an active layer 130, a P-type semiconductor layer 140, and a first transparent electrode layer 150 are formed on the substrate 110. The first transparent electrode layer 150 in the predetermined region is etched, but the first transparent electrode layer 150 is left in a predetermined thickness. Subsequently, the N-type semiconductor layer 120 is exposed by removing the first transparent electrode layer 150, the P-type semiconductor layer 140, and the active layer 130 that remain in a predetermined thickness by performing continuous etching. At this time, unevenness having a predetermined roughness is formed on the surface of the N-type semiconductor layer 120 by the above-described process.

Thereafter, an N-type metal pad 165 is formed on the N-type semiconductor layer 120. In this case, the P electrode 180 may be simultaneously formed together with the N-type metal pad 165, or the P electrode 180 may be formed first, and then the N-type metal pad 165 may be formed. In addition, the P electrode 180 may be formed after the N-type metal pad 165 is formed.

Next, the second transparent electrode 160 is formed on the N-type semiconductor layer 120 on which the N-type metal pad 165 is formed. The second transparent electrode 160 is formed to be spaced apart from the active layer 130 by a predetermined interval, and is formed in a shape surrounding the N-type metal pad 165. In addition, after forming the second transparent electrode 160, the P electrode 180 may be formed. In this case, a portion of the second transparent electrode 160 may be removed to open a portion of the region of the N-type metal pad 165 connected to the N pad. That is, the second transparent electrode 160 is formed to surround the N-type metal pad 165, but the upper portion of the N-type metal pad 165 corresponding to the wire bonding region of the subsequent packaging process is opened. In this case, a part of the second transparent electrode 160 may be removed through a predetermined patterning process.                     

Hereinafter, the light emitting element formed by the above-mentioned description is demonstrated.

As shown in FIG. 2 and FIG. 3, the light emitting device of the present invention includes a substrate 110, an N-type semiconductor layer 120 formed on the substrate 110, and a predetermined region of the N-type semiconductor layer 120. The P-type semiconductor layer 140 formed, the first transparent electrode layer 150 formed on the P-type semiconductor layer 140, the P electrode 180 formed on the first transparent electrode layer 150, and the N-type semiconductor layer An N electrode 170 formed on the 120, but has a predetermined roughness on the surface of the N-type semiconductor layer 120 where the P-type semiconductor layer 140 is not formed. In this case, an active layer 130 is further formed below the P-type semiconductor layer 140. In addition, a buffer layer (not shown) is further formed between the N-type semiconductor layer 120 and the substrate 110. As the N electrode 170, a second transparent electrode layer 160 is used. As the N electrode 170, a second transparent electrode layer 160 formed on the N-type semiconductor layer 120 and an N-type metal pad 165 formed on a predetermined region of the second transparent electrode layer 160 may be used. It may be. In addition, the N electrode 170 is formed on an N-type metal pad 165 formed on a predetermined region of the N-type semiconductor layer 120 and on the N-type semiconductor layer 120 including the N-type metal pad 165. The second transparent electrode layer 160 may be used.

It is preferable to deposit or grow a reflective metal layer having a thickness of 0.001 μm to 2.0 μm on the back surface of the ITO of the present invention.

Through this, it is possible to maximize the light output by increasing the light emitting area not only the existing emission area but also the etched N-type semiconductor area.

 As described above, in the present invention, by forming a transparent electrode layer on the exposed N-type semiconductor layer of the light emitting device, and using it as the N electrode, the light emitting area can be enlarged and the light output can be maximized.

In addition, the quantum efficiency of the light emitting device can be improved by forming irregularities having a predetermined roughness on the surface of the N-type semiconductor layer so that light can be emitted from the N-type semiconductor layer.

Claims (10)

Forming an N-type semiconductor layer, a P-type semiconductor layer, and a first transparent electrode layer on the substrate; Exposing the N-type semiconductor layer by removing the first transparent electrode layer and the P-type semiconductor layer in a predetermined region; And Forming a second transparent electrode layer on the exposed N-type semiconductor layer, but spaced apart from the P-type semiconductor layer and the first transparent electrode layer by a predetermined distance. The method according to claim 1, The manufacturing method of the light emitting element in which the active layer was formed between the said N type semiconductor layer and the said P type semiconductor layer. The method of claim 1, wherein exposing the N-type semiconductor layer, Forming a predetermined photoresist pattern on the first transparent electrode layer; Removing a part of the first transparent electrode layer by performing a first etching process using the photoresist pattern as an etching mask; Exposing the N-type semiconductor layer by removing the remaining first transparent electrode layer, the P-type semiconductor layer, and the active layer by performing a second etching process using the photoresist pattern as an etching mask; Giving unevenness with a predetermined roughness to the upper surface; And Removing the photoresist pattern. The method according to any one of claims 1 to 3, Forming a P electrode on the first transparent electrode layer, and forming an N-type metal pad on the second transparent electrode layer. The method according to any one of claims 1 to 3, Forming a P electrode on the first transparent electrode layer, and after exposing the N-type semiconductor layer, forming an N-type metal pad on the N-type semiconductor layer. . Board; An N-type semiconductor layer formed on the substrate; A P-type semiconductor layer formed on a predetermined region of the N-type semiconductor layer; A first transparent electrode layer formed on the P-type semiconductor layer; A P electrode formed on the first transparent electrode layer; And And an N electrode formed on the N-type semiconductor layer and including a second transparent electrode layer. The method according to claim 6, A light emitting device having a predetermined roughness on the surface of the N-type semiconductor layer in which the P-type semiconductor layer is not formed. The method according to claim 6, The light emitting device further comprises an active layer formed under the P-type semiconductor layer. The method according to any one of claims 6 to 8, wherein the N electrode, A second transparent electrode layer formed on the N-type semiconductor layer; And A light emitting device comprising a metal pad formed on a predetermined region of the second transparent electrode layer. The method according to any one of claims 6 to 8, wherein the N electrode, A metal pad formed on a predetermined region of the N-type semiconductor layer; And A light emitting device comprising a second transparent electrode layer formed on the N-type semiconductor layer including the metal pad.

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