KR101077769B1 - Luminescence device and method of manufacturing the same - Google Patents

Abstract

The present invention relates to a light emitting device and a method of manufacturing the same, which comprises forming an N-type semiconductor layer, an active layer, a P-type semiconductor layer, and a transparent electrode layer on a substrate, and forming irregularities having a predetermined roughness on the surface of the transparent electrode layer. Exposing the N-type semiconductor layer by removing the transparent electrode layer, the P-type semiconductor layer, and the active layer in a predetermined region; and forming an electrode on the exposed N-type semiconductor layer and the transparent electrode layer. A method of manufacturing a light emitting device, comprising: a sapphire substrate, an N-type semiconductor layer formed on the sapphire substrate, an active layer, a P-type semiconductor layer and a transparent electrode layer sequentially formed on a predetermined region of the N-type semiconductor layer, and the N The N-type semiconductor layer including an electrode formed on each of the semiconductor layer and the transparent electrode, the transparent electrode layer and / or the active layer is not formed To provide a light emitting device having a predetermined roughness.

As a result, irregularities having a predetermined roughness may be formed on the transparent electrode surface and the N-type semiconductor layer surface of the light emitting device to improve external quantum efficiency of the light emitting device.

Light emitting element, transparent electrode, roughness, surface irregularities treatment, gallium nitride, ion treatment

Description

Light emitting device and method for manufacturing same             

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

2A to 2E are cross-sectional views illustrating a method of manufacturing a light emitting device according to 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: transparent electrode 60, 70, 160, 170: electrode

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

155 photosensitive film pattern

The present invention relates to a light emitting device and a method for manufacturing the same, and more particularly, to surface treatment of a transparent electrode and an N semiconductor layer.

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 is formed to expose only the upper portion of the P-GaN layer 40, 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 causes photons (light) generated in the active layer 30 to exit the sapphire substrate 10 below the light emitting chip as well as the top of the light emitting chip. At this time, a part of the photons emitted to the upper portion of the light emitting chip may be reflected on the surface of the smooth transparent electrode 50, and the reflected photons may be canceled out from other photons generated in the active layer 30. In addition, most of the photons emitted under the light emitting chip may be absorbed by the sapphire substrate 10 or reflected from the substrate to cancel out other photons generated in the active layer 30.

Accordingly, many studies have been conducted to improve external quantum efficiency of such light emitting devices.

Accordingly, in order to solve the above problems, the present invention provides a predetermined roughness on the surface of the transparent electrode to increase the quantum efficiency of the light emitting device, and gives the roughness on the exposed N-type semiconductor layer to effectively increase the quantum efficiency. It is an object of the present invention to provide a light emitting device and a method of manufacturing the same.

Forming an N-type semiconductor layer, an active layer, a P-type semiconductor layer, and a transparent electrode layer on a substrate according to the present invention, forming irregularities having a predetermined roughness on a surface of the transparent electrode layer, and forming the transparent electrode layer in a predetermined region And removing the P-type semiconductor layer and the active layer to expose the N-type semiconductor layer and forming an electrode on the exposed N-type semiconductor layer and the transparent electrode layer. do.

Unevenness is placed on the surface of the transparent electrode layer through ion treatment using the ions. In addition, ion treatment is performed using Ar ions so that the roughness of the unevenness is 50 to 50000 Pa. The exposing the N-type semiconductor layer by removing the transparent electrode layer, the P-type semiconductor layer, and the active layer in a predetermined region may include forming a predetermined photoresist pattern on the transparent electrode layer and etching the photoresist pattern. Performing a first etching process using a mask to remove a portion of the transparent electrode layer; and performing a second etching process using the photoresist pattern as an etching mask to remove the transparent electrode layer, the P-type semiconductor layer, and the active layer. And removing the photoresist pattern.

The present invention also provides a method for forming an N-type semiconductor layer, an active layer, a P-type semiconductor layer, and a transparent electrode layer on a substrate, removing a portion of the transparent electrode layer in a predetermined region, and remaining in the region where the portion is removed. Removing the P-type semiconductor layer and the active layer under the transparent electrode layer and the active layer to expose the N-type semiconductor layer, forming irregularities having a predetermined roughness on the N-type semiconductor layer surface, and the exposed N-type It provides a method of manufacturing a light emitting device comprising forming an electrode on the semiconductor layer and the transparent electrode layer.

The present invention also provides a sapphire substrate, an N-type semiconductor layer formed on the sapphire substrate, an active layer sequentially formed on a predetermined region of the N-type semiconductor layer, a P-type semiconductor layer and a transparent electrode layer, and the N-type semiconductor layer; A light emitting device including an electrode formed on the transparent electrode and having a predetermined roughness on a surface of the N-type semiconductor layer in which the transparent electrode layer and / or the active layer is not provided is provided. At this time, the roughness is preferably 50 to 50000 Pa.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It will be apparent to those skilled in the art that the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, It is provided to let you know. Like numbers refer to like elements in the figures.

2A to 2E 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 transparent electrode layer 150 are sequentially formed on the sapphire substrate 110.

The semiconductor layers 120 and 140 and the active layer 130 may include metal organic chemical vapor deposition (MOCVD), molecular beam epitaxial growth (MBE), hydride gas phase growth (HVPE); It is formed through various deposition and growth methods including Hydride Vapor Phase Epitaxy. The N-type semiconductor layer 120 preferably uses a gallium nitride (GaN) film implanted with N-type impurities, and is not limited thereto. A material layer having various semiconductor properties may be used. In addition, the P-type semiconductor layer 140 also uses a gallium nitride film implanted with P-type impurities. In addition, the contact resistance between the upper transparent electrode layer 150 and the P-type semiconductor layer 140 is reduced by high concentration ion implantation into the P-type semiconductor layer 140. 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.

In addition, an InGaN film is used as the active layer 130, and a multi-quantum well structure is inserted to increase efficiency. 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, the present invention is not limited to the above-described structure, and various layers may be further formed between each layer according to the characteristics of the light emitting device. That is, a separate buffer layer may be further formed between the N-type semiconductor layer and the substrate. Moreover, it can also be comprised by the layer which consists of many films as an active layer. Indium Tin Oxide (ITO) is used as the transparent electrode.

Referring to FIG. 2B, predetermined irregularities are applied to the surface of the transparent electrode layer 150 through a surface irregularities treatment process. It is preferable that roughness Ra of the unevenness | corrugation by this invention is about 100-3000 GPa. To this end, in the present embodiment, it is preferable to give irregularities to the surface of the transparent electrode layer 150 through ion treatment using predetermined ions. At this time, it is effective to use Ar ion as the ion. Ion treatment refers to treatment using a physical reaction using the ionization energy of ions as well as chemical reactions by ions. Of course, not limited to such an ion treatment, various methods that can give a surface roughness such as polishing, etching, etc. may be used. In addition, since a part of the transparent electrode layer 150 may be removed during the surface irregularities treatment process, it is preferable to form the thickness of the transparent electrode layer 150 by about 1 to 50% thicker than the conventional one in order to compensate for this.

As described above, by providing predetermined irregularities on the surface of the transparent electrode layer 150, the light emitting efficiency of about 5 to 15% can be improved as compared with the conventional light emitting device. This is because photons that have been reflected on the surface of the conventional transparent transparent electrode layer 150 exit outside the transparent electrode layer 150 without being reflected by the rough surface.

2C and 2D, a portion of the N-type semiconductor layer 120 under the active layer is exposed through predetermined mask patterning. In addition, in the present invention, the surface of the exposed N-type semiconductor layer 120 gives irregularities. The roughness Ra of the unevenness of the N-type semiconductor layer 120 is preferably 50 to 50000 Pa.

In order to expose a portion of the lower N-type semiconductor layer 120, first, a photoresist film is coated on the transparent electrode layer 150, and then a photoresist pattern 155 is formed through a photolithography process using a mask. In this case, the photoresist pattern 155 is 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 photosensitive film pattern 155 is viewed from above, 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 is open.

Thereafter, a part of the exposed transparent electrode layer 150 is removed by performing a first etching process using the photoresist pattern as an etching mask. At this time, the remaining thickness of the transparent electrode layer 150 is 1 to 500 내지. Subsequently, the 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 to expose the N-type semiconductor layer 120 and give predetermined irregularities to the surface thereof. Can be. 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, when the transparent electrode layer 150, the P-type semiconductor layer 140, and the active layer 130 which remain through dry etching without removing the entire transparent electrode layer 150 through wet etching are removed, the N-type semiconductor is removed. The surface of layer 120 is roughened. This is because the transparent electrode layer 150 serves 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 predetermined irregularities.

A portion of the N-type semiconductor layer 120 is etched as shown in FIG. 2D during the second etching process. Of course, the etching parameters may be well adjusted during etching to prevent a portion of the N-type semiconductor layer 120 from being etched. In addition, the transparent electrode layer 150 may be completely removed during the first etching process.

As described above, the surface of the exposed N-type semiconductor layer 120 of the light emitting device may be provided with a predetermined unevenness to emit light in the N-type semiconductor layer 120. The efficiency can be improved by 40 to 70%.

Referring to FIG. 2E, after removing the photoresist pattern, a predetermined cleaning process is performed. Thereafter, the N electrode 160 is formed on the N-type semiconductor layer 120 opened through the electrode pad forming process, and the P electrode 170 is formed on the transparent electrode layer 150.

The light emitting device of the present invention is not limited to the above-described process steps, and various process steps can be changed. That is, an N-type semiconductor layer, an active layer, a P-type semiconductor layer, and a transparent electrode are formed, a roughness is applied to the surface of the transparent electrode, and a part of the N-type semiconductor layer is exposed by etching a part of the transparent electrode, the P-type semiconductor layer, and the active layer. Next, an electrode may be formed on the exposed N-type semiconductor layer and the transparent electrode, respectively. This can improve the quantum efficiency of about 10%. In addition, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a transparent electrode are formed, and a portion of the transparent electrode in a predetermined region is removed to leave a transparent electrode having a thickness of several tens of 에 in a predetermined region, The lower portion of the P-type semiconductor layer and the active layer may be etched to expose a portion of the N-type semiconductor layer, and then electrodes may be formed on the exposed N-type semiconductor layer and the transparent electrode, respectively. In addition, an N-type semiconductor layer, an active layer, a P-type semiconductor layer and a transparent electrode are formed, and a portion of the N-type semiconductor layer is exposed by etching a portion of the transparent electrode, the P-type semiconductor layer and the active layer, and then exposing the exposed N-type. After roughening the surface of the semiconductor layer, the electrodes may be formed on the transparent electrodes, respectively. As a result, light emission efficiency of about 50% can be improved. 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.

As described above, the present invention can improve the external quantum efficiency of the light emitting device by forming irregularities having a predetermined roughness on the transparent electrode surface of the light emitting device.

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 (7)

Forming an N-type semiconductor layer, an active layer, a P-type semiconductor layer, and a transparent electrode layer on the substrate; Forming unevenness having a predetermined roughness on the surface of the transparent electrode layer through ion treatment using ions on the surface of the transparent electrode layer; Exposing the N-type semiconductor layer by removing the transparent electrode layer, the P-type semiconductor layer, and the active layer in a predetermined region; And Forming an electrode on the exposed N-type semiconductor layer and the transparent electrode layer. delete The method according to claim 1, A method of manufacturing a light emitting device to perform ion treatment using Ar ions so that the roughness of the unevenness is 50 to 50000 Pa. The method of claim 1 or 3, wherein removing the transparent electrode layer, the P-type semiconductor layer and the active layer in a predetermined region to expose the N-type semiconductor layer, Forming a predetermined photoresist pattern on the transparent electrode layer; Removing a part of the transparent electrode layer by performing a first etching process using the photoresist pattern as an etching mask; Removing the 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; And The method of manufacturing a light emitting device comprising the step of removing the photosensitive film pattern. Forming an N-type semiconductor layer, an active layer, a P-type semiconductor layer, and a transparent electrode layer on the substrate; Performing a first etching process to remove a portion of the transparent electrode layer in a predetermined region; After the first etching process is completed, a second etching process is performed to remove the transparent electrode layer and the P-type semiconductor layer and the active layer below the partially exposed region, thereby exposing the N-type semiconductor layer. Forming irregularities on the surface of the N-type semiconductor layer by the remaining transparent electrode layers; And Forming an electrode on the exposed N-type semiconductor layer and the transparent electrode layer. delete delete

Images