KR100905859B1 - Nitride semiconductor light emitting device and manufacturing method thereof - Google Patents

Abstract

A method of manufacturing a nitride semiconductor light emitting device is disclosed. The method of manufacturing the nitride semiconductor light emitting device includes forming a nitride single crystal base layer on a nitride single crystal growth substrate, forming an insulating pattern layer having a plurality of window regions on the nitride single crystal base layer, and exposing the window region. Growing a first nitride single crystal layer having a hexagonal pyramid structure in the upper surface region of the nitride single crystal base layer, having a refractive index different from that of the first nitride single crystal layer, and filling a space between the first nitride single crystal layers having a hexagonal pyramid structure Forming a second nitride single crystal layer having a surface, forming a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer on the second nitride single crystal layer, a nitride single crystal growth substrate, and a nitride single crystal base The uneven pattern is formed on one surface of the first nitride single crystal layer by removing the layer and the insulating pattern layer. Forming a first electrode on the first nitride single crystal layer and forming a second electrode on the light emitting structure.

Light emitting element, hexagonal pyramid, irregular pattern, GaN

Description

Nitride semiconductor light emitting device and manufacturing method thereof

The present invention relates to a nitride semiconductor light emitting device for improving light extraction efficiency and a method of manufacturing the same.

Recently, Group III nitride semiconductors (hereinafter, simply referred to as 'nitride semiconductors') have been widely used as light emitting device materials for ultraviolet (UV) light, blue light, and green light in various fields such as LCD backlights, camera flashes, and lighting. Generally, the nitride semiconductor has a composition formula of _{Al x Ga y In 1 -x- y} N (0≤x≤1, 0≤y≤1, 0≤x + y≤1). In order to manufacture such a nitride semiconductor light emitting device (including an LED), an n-type nitride semiconductor layer, an active layer and a p-type nitride semiconductor layer are sequentially grown on a growth substrate such as sapphire to form a light emitting structure.

Nitride semiconductors have a higher refractive index than external environments such as epoxy or air. Due to the large difference in refractive index between the external environment (resin such as air or epoxy) and the nitride semiconductor, a substantial portion of the light generated inside the nitride semiconductor light emitting device is reflected several times at the interface or the wall and cannot escape to the outside. Extinct from Since the light loss due to the total internal reflection is very large, the light extraction efficiency of the nitride semiconductor light emitting device is not high enough.

1 is a vertical cross-sectional view of a nitride semiconductor light emitting device according to the prior art. Referring to FIG. 1, the light emitting device 10 includes a p-type semiconductor layer 13, an active layer 14, and an n-type semiconductor layer sequentially formed on the first electrode 11, the reflective layer 12, and the reflective layer 12. A light emitting structure comprising a 15 and a second electrode 16 is included.

Light emitted from the active layer 14 by recombination of electrons and holes may have various propagation angles. In order for the light to be emitted to the outside through the wall or the interface of the light emitting device, the propagation angle of the light must be smaller than the critical angle θ _c . Lost as heat. Due to such total internal reflection and heat loss, the light extraction efficiency of the nitride semiconductor light emitting device has a low value.

The present invention is to solve the above problems, an object of the present invention, by forming a nitride single crystal layer having an upper surface having an uneven pattern on the top of the light emitting structure, the lower surface of the hexagonal pyramid structure, thereby improving the light extraction efficiency To provide a nitride semiconductor light emitting device and a method for manufacturing the same.

In the method for manufacturing a nitride single crystal semiconductor according to an embodiment of the present invention for achieving the above object, the step of forming a nitride single crystal base layer on the nitride single crystal growth substrate, a plurality of windows on the nitride single crystal base layer Forming an insulating pattern layer having a region, growing a first nitride single crystal layer having a hexagonal pyramid structure in an upper surface region of the nitride single crystal base layer exposed to the window region, and having a refractive index different from that of the first nitride single crystal layer; Filling a space between the first nitride single crystal layers of the hexagonal pyramid structure to form a second nitride single crystal layer having a flat surface; a first semiconductor layer, an active layer, and a second semiconductor layer on the second nitride single crystal layer Forming a light emitting structure comprising a, the nitride single crystal growth substrate, the nitride Removing a crystal base layer and the insulating pattern layer to form an uneven pattern on one surface of the first nitride single crystal layer, forming a first electrode on the first nitride single crystal layer, and forming a first electrode on the light emitting structure Forming two electrodes.

In this case, the first nitride single crystal layer may be made of undoped GaN.

In addition, the insulating pattern layer may be made of a material having a porous deposition characteristics, preferably made of a SiN material.

In addition, the second nitride single crystal layer may be made of one of AlGaN, SiN, and InGaN.

On the other hand, removing the nitride single crystal growth substrate, the nitride single crystal base layer and the insulating pattern layer to form an uneven pattern on one surface of the first nitride single crystal layer, the laser substrate and the nitride single crystal growth substrate Irradiating and separating the nitride single crystal base layer and removing the insulating pattern layer through etching.

The forming of the second electrode on the light emitting structure may include forming a reflective layer on the light emitting structure, forming the second electrode under the reflective layer, and forming a silicon submount substrate on the second electrode. Forming a step.

In the nitride semiconductor light emitting device according to the embodiment of the present invention, the upper surface is formed with an uneven pattern, the lower surface has a refractive index different from that of the first nitride single crystal layer, the first nitride single crystal layer formed of a hexagonal pyramid structure A light emitting device including a first nitride layer, an active layer, and a second semiconductor layer formed under the second nitride single crystal layer having a flat surface by filling a space between the first nitride single crystal layers having a hexagonal pyramid structure, and having a flat surface. A structure, a first electrode formed on the first nitride single crystal layer, and a second electrode formed under the light emitting structure.

In this case, the first nitride single crystal layer may be made of undoped GaN. In addition, the second nitride single crystal layer may be made of one of AlGaN, SiN, and InGaN.

The nitride semiconductor light emitting device may further include a reflective layer formed between the light emitting structure and the second electrode to reflect light, and a sub mount formed below the second electrode to emit heat.

According to the present invention, by forming a nitride single crystal layer having a hexagonal pyramid structure on the lower surface, it is possible to increase the amount of light incident in the nitride single crystal layer and to reduce the incident angle of light to improve the light extraction efficiency of the nitride semiconductor light emitting device. .

In addition, by forming the upper surface of the nitride single crystal layer in an uneven pattern, it is possible to improve the linearity of the light to improve the light extraction efficiency of the nitride semiconductor light emitting device.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

2A to 2F are flowcharts illustrating a method of manufacturing a semiconductor light emitting device according to an embodiment of the present invention. Referring to FIG. 2A, first, a nitride single crystal base layer 120 and an insulating pattern layer 130 are sequentially deposited on the nitride single crystal growth substrate 110. In this case, the nitride single crystal growth substrate 110 may be a sapphire substrate or a Si substrate, and the nitride single crystal base layer 120 is formed through deposition of an undoped gallium nitride (GaN) -based material. In addition, the insulating pattern layer 130 may be formed by depositing an insulating material having a porous deposition property such as SiN. In this case, the insulating pattern layer 130 may have a plurality of windows formed in the deposition process by the porous deposition characteristics.

Thereafter, as illustrated in FIG. 2B, the nitride single crystal base layer 120 is regrown to form the first nitride single crystal layer 140. In this case, the first nitride single crystal layer 140 is formed through the growth of the nitride single crystal base layer 120 exposed through the window region of the insulating pattern layer 130 and has a hexagonal pyramid structure. In addition, the first nitride single crystal layer 140 is formed of the same gallium nitride (GaN) -based material as the nitride single crystal base layer 120.

As illustrated in FIG. 2C, the second nitride single crystal layer 150 is formed over the first nitride single crystal layer 140. Specifically, the second nitride single crystal layer 150 is formed to fill a space between the first nitride single crystal layer 140 having a hexagonal pyramid structure, and is formed to have a flat surface. In this case, the second nitride single crystal layer 150 may be formed of a material having a refractive index different from that of the first nitride single crystal layer 140. Preferably, the second nitride single crystal layer 140 has a refractive index greater than that of the first nitride single crystal layer 140. It can be formed of a material having. Specifically, it may be formed of any one of AlGaN, SiN and InGaN.

Next, as illustrated in FIG. 2D, the first semiconductor layer 160, the active layer 170, and the second semiconductor layer 180 are sequentially formed on the second nitride single crystal layer 150. In detail, the first semiconductor layer 160 may be formed by doping an n-type dopant such as Si, In, or Sn into a GaN semiconductor material. In this case, when the second nitride single crystal layer 150 is formed of AlGaN or InGaN, the first semiconductor layer 160 may be formed by doping an n-type dopant on the second nitride single crystal layer 150. have. In addition, when the second nitride single crystal layer 150 is formed of SiN having porous deposition characteristics, a method of growing by doping an n-type dopant on the second nitride single crystal layer 150 exposed through the window region of SiN. As a result, the first semiconductor layer 160 may be formed.

In addition, the active layer 170 may be formed in a form having a single or multiple quantum well structure using a GaN-based material such as GaN or InGaN. The second semiconductor layer 180 may be formed by doping a p-type dopant such as Zn, Cd, Mg, or the like into the GaN semiconductor material. In this case, each of the first semiconductor layer 160, the active layer 170, and the second semiconductor layer 180 may be formed using a deposition method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). have.

Thereafter, as shown in FIG. 2E, the nitride single crystal growth substrate 110 and the nitride single crystal base layer 120 are removed on the structure shown in FIG. 2D by using a laser lift off method. In detail, an excimer laser of 248 nm may be irradiated on the lower portion of the structure to remove the nitride single crystal growth substrate 110 and the nitride single crystal base layer 120. After the nitride single crystal growth substrate 110 and the nitride single crystal base layer 120 are removed, the first nitride single crystal layer 140 may be exposed by removing the insulating pattern layer 130 using a semiconductor etching method. To help. In this case, the first nitride single crystal layer 140 can be clearly seen that the uneven pattern is formed by removing the insulating pattern layer 130.

On the other hand, the structure shown in Figure 2f is a picture of rotating the structure shown in Figure 2e 180 °. In this structure, the first electrode 194 is formed on the first nitride single crystal layer 140 having an uneven pattern, and the reflective layer 191, the second electrode 192, and the sub are formed under the second semiconductor layer 180. The mounts 193 are formed sequentially. In this case, the first electrode 194 may be an n-electrode, and the second electrode 192 may be a p-electrode.

The reflective layer 192 reflects the light generated by the active layer 170 and output to the lower surface of the light emitting structure, so that the reflective layer 192 can be extracted to the outside through the second nitride semiconductor layer 150 and the first nitride single crystal layer 140. do. Therefore, the reflective layer 192 is preferably formed of a metal material having a high reflectance. Specifically, it may be formed of a material such as Al, Ti and Cu.

When the nitride semiconductor light emitting device 100 is manufactured according to the above method, the light extraction efficiency may be improved through a hexagonal pyramid structure formed on the lower surface of the first nitride single crystal layer 140 and an uneven pattern formed on the upper surface. do.

FIG. 3 is a schematic diagram showing a light extraction path in the semiconductor light emitting device shown in FIG. 2F. Referring to FIG. 3, light is generated in the active layer 170 by recombination of electrons and holes. This light is refracted by the difference in refractive index at the interface between the first semiconductor layer 160 and the second nitride single crystal layer 150 and is incident. In this case, light incident on the second nitride single crystal layer 150 may be incident on the first nitride single crystal layer 140 without losing light through an interface of a hexagonal pyramid structure of the first nitride single crystal layer 140. . In addition, even if the incident angle of the light incident on the second nitride single crystal layer 150 is large, it is totally reflected so that it can be incident on the first nitride single crystal layer 140 through another hexagonal pyramid located on the side to reduce the light loss. do.

In addition, as shown in FIG. 3, the incidence angle of the light incident on the first nitride single crystal layer 140 may be reduced by the inclined interface of the hexagonal pyramid structure of the first nitride single crystal layer 140. Accordingly, when light is output to the outside through the first nitride single crystal layer 140, light loss may be reduced. In addition, as the light incident on the first nitride single crystal layer 140 is output through the uneven pattern formed on the upper surface, the linearity of the light may be improved.

While the above has been shown and described with respect to preferred embodiments of the invention, the invention is not limited to the specific embodiments described above, it is usually in the art to which the invention belongs without departing from the spirit of the invention claimed in the claims. Various modifications can be made by those skilled in the art, and these modifications should not be individually understood from the technical spirit or the prospect of the present invention.

1 is a vertical cross-sectional view of a nitride semiconductor light emitting device according to the prior art,

2A to 2F are process diagrams for explaining a method of manufacturing a semiconductor light emitting device according to an embodiment of the present invention, and

FIG. 3 is a schematic diagram showing a light extraction path in the semiconductor light emitting device shown in FIG. 2F.

<Description of Signs for Main Parts of Drawings>

100 semiconductor light emitting device 110 sapphire substrate

120: nitride single crystal growth layer 130: insulating pattern layer

140: nitride single crystal layer 150: light transmitting layer

160: first semiconductor layer 170: active layer

180: second semiconductor layer 191: first electrode

192: reflective layer 193: second electrode

194: submount

Claims (11)

Forming a nitride single crystal base layer on the nitride single crystal growth substrate; Forming an insulating pattern layer having a plurality of window regions on the nitride single crystal base layer; Growing a first nitride single crystal layer having a hexagonal pyramid structure in the upper surface region of the nitride single crystal base layer exposed to the window region; Forming a second nitride single crystal layer having a flat surface by filling a space between the first nitride single crystal layer having a different refractive index than the first nitride single crystal layer and having a hexagonal pyramid structure; Forming a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer on the second nitride single crystal layer; And, Forming an uneven pattern on one surface of the first nitride single crystal layer by removing the nitride single crystal growth substrate, the nitride single crystal base layer and the insulating pattern layer; Forming a first electrode on the first nitride single crystal layer; And, Forming a second electrode on the light emitting structure; Method of manufacturing a nitride semiconductor light emitting device comprising a. The method of claim 1, The first nitride single crystal layer, A method of manufacturing a nitride semiconductor light emitting device, characterized in that it is made of undoped GaN. The method of claim 1, The insulating pattern layer, Method of manufacturing a nitride semiconductor light emitting device, characterized in that made of a material having a porous deposition characteristics. The method of claim 1, The insulating pattern layer, A method of manufacturing a nitride semiconductor light emitting device, characterized in that the SiN material. The method of claim 1, The second nitride single crystal layer, A method of manufacturing a nitride semiconductor light emitting device, characterized in that the material is made of any one of AlGaN, SiN and InGaN. The method of claim 1, Removing the substrate for nitride single crystal growth, the nitride single crystal base layer and the insulating pattern layer to form an uneven pattern on one surface of the first nitride single crystal layer, Irradiating and separating a laser onto the nitride single crystal growth substrate and the nitride single crystal base layer; And, Removing the insulating pattern layer through etching; and manufacturing a nitride semiconductor light emitting device. The method of claim 1, Forming a second electrode on the light emitting structure, Forming a reflective layer on the light emitting structure; Forming the second electrode under the reflective layer; And, Forming a silicon submount substrate on the second electrode; and manufacturing a nitride semiconductor light emitting device. A first nitride single crystal layer having an upper surface formed of a concave-convex pattern and a lower surface formed of a hexagonal pyramid structure; A second nitride single crystal layer having a refractive index different from that of the first nitride single crystal layer and having a flat surface by filling a space between the first nitride single crystal layers of the hexagonal pyramid structure; A light emitting structure formed under the second nitride single crystal layer and including a first semiconductor layer, an active layer, and a second semiconductor layer; A first electrode formed on the first nitride single crystal layer; And, And a second electrode formed under the light emitting structure. The method of claim 8, The first nitride single crystal layer, A nitride semiconductor light emitting device comprising an undoped GaN. The method of claim 8, The second nitride single crystal layer, A nitride semiconductor light emitting device, comprising: any one of AlGaN, SiN, and InGaN. The method of claim 8, A reflective layer formed between the light emitting structure and the second electrode to reflect light; And, And a sub-mount formed under the second electrode to dissipate heat.

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