KR101552670B1 - Semiconductor Light Emitting Diode with Improved Current Spreading Performance and High Brightness Comprising Trench Isolating Light Emitting Region - Google Patents

Abstract

The present invention relates to a semiconductor light emitting device including a light emitting region isolation trench and a contact hole structure.
INDUSTRIAL APPLICABILITY The semiconductor light emitting device of the present invention can evenly distribute the current flowing through the semiconductor layer, thereby widening the effective light emitting area.
As the light emitting regions are separated by the light emitting region separation trench, the same effect as that of the individual elements connected in parallel can be obtained, and the light efficiency can also be expected to be improved.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a semiconductor light emitting device and a method of manufacturing the same. 2. Description of the Related Art [0002] Semiconductor Light Emitting Diode (OLED)

The present invention relates to a semiconductor light emitting device including a light emitting region isolation trench and a contact hole structure and exhibiting excellent current dispersion effect and improved luminance characteristics.

Examples of conventional semiconductor devices include GaN-based nitride semiconductor devices. The GaN-based nitride semiconductor light emitting device has been widely used for blue light or green LED light emitting devices, high-speed switching devices such as MESFETs and HEMTs, Has been applied.

In particular, blue or green LED light-emitting devices have already been mass-produced, and global sales are increasing.

1 schematically shows a general nitride-based light-emitting device.

Referring to FIG. 1, a nitride-based light-emitting device is formed from a growth substrate 11. Bo

More specifically, the nitride-based light emitting device includes an n-type nitride semiconductor layer 12, an active layer 13, and a p-type nitride semiconductor layer 14.

At this time, in order to inject electrons into the n-type nitride semiconductor layer 12, the n-type electrode pad 15 is formed so as to be electrically connected to the n-type nitride semiconductor layer 12. A p-side electrode pad 16 is formed so as to be electrically connected to the p-type nitride semiconductor layer 14 in order to inject holes into the p-type nitride semiconductor layer 14. [

However, since the p-type nitride semiconductor layer has a high resistivity, the current can not be uniformly dispersed in the p-type nitride semiconductor layer, and a current is concentrated in a portion where the p-side electrode pad is formed. Further, the current flows through the semiconductor layers and escapes to the n-side electrode pad. Accordingly, a current is concentrated at a portion where the n-type electrode pad is formed in the n-type nitride semiconductor layer, and current flows intensively through the edge of the light emitting diode. The concentration of the current as described above leads to reduction of the light emitting region and consequently degrades the luminous efficiency.

In particular, the planar light emitting device in which two electrodes are arranged substantially horizontally on the upper surface of the light emitting structure has a problem that the current flow is not uniformly distributed in the entire light emitting region as compared with the vertical structure light emitting device, There is a problem that the effective area to participate is not large.

On the other hand, for the purpose of high output such as a light emitting element for illumination, the light emitting element is gradually becoming larger than about 1 mm 2. However, it is more difficult to realize a uniform current distribution over the entire area as the light emitting device becomes larger in size. As described above, the problem of the current dispersion efficiency due to the large area is recognized as an important technical problem in the semiconductor light emitting device.

In order to improve the current density and improve the area efficiency, it has been studied mainly to improve the shape and arrangement of various p-side and n-side electrodes. For example, U.S. Patent No. 6,486,499 discloses that the n-side electrode and the p-side electrode include a plurality of electrode fingers extended to be spaced apart from each other by a predetermined distance. Through this electrode structure, an additional current path was provided, a wide effective light emitting area was secured, and a uniform current flow was attempted.

However, in this electrode structure, as the current density increases in the p-type semiconductor layer in the vicinity of the p-side electrode, the output efficiency is lowered and the current dispersion efficiency is limited.

Therefore, there is a continuing need to develop a semiconductor light emitting device capable of uniformly distributing the current flowing through the semiconductor layer.

As a result of research and development to develop a semiconductor light emitting device having a structure capable of exhibiting an excellent current dispersion effect, the present inventors have found that a first semiconductor layer exposed in a contact hole formed above the first semiconductor layer, A first elongated electrode electrically connecting the second semiconductor layer and the first elongated electrode, forming a trench capable of separating the light emitting region into a plurality of elongated holes, and between the second elongated semiconductor layer and the first elongated electrode, between the sidewall of the contact hole and the first elongated electrode, It has been found that when a semiconductor light emitting device having a plurality of light emitting regions is formed by forming an insulating layer between the surface of the trench and the first elongated electrode, the current dispersion can be maximized and the brightness can be improved.

Accordingly, an object of the present invention is to provide a semiconductor light emitting device having an electrode structure and a trench for isolating a light emitting region, which exhibit an excellent current dispersion effect.

In order to achieve the above object, the present invention provides a semiconductor light emitting device including a first semiconductor layer, an active layer, and a second semiconductor layer, and includes a current diffusion contact hole and a trench.

The semiconductor light emitting device of the present invention is characterized in that a plurality of light emitting regions are separated by the trench.

The semiconductor light emitting device of the present invention is characterized in that the current diffusion contact hole is formed to expose the first semiconductor layer and a first extension for electrically connecting the first semiconductor layer exposed by the current diffusion contact hole And an electrode and a second elongated electrode electrically connected to the second semiconductor layer.

The semiconductor light emitting device of the present invention further includes an insulating layer electrically isolating the first extended electrode from the active layer, the second semiconductor layer, or the trench region, and electrically isolating the second extended electrode from the trench region, And the insulating layer is formed between the second semiconductor layer and the first extended electrode, between the sidewall of the current diffusion contact hole and the first extended electrode, and between the surface of the trench and the first extended electrode.

The semiconductor light emitting device of the present invention can spread the current flowing through the semiconductor layer evenly and widen the effective light emitting area.

As the light emitting regions are separated by the light emitting region separation trench, the same effect as that of the individual elements connected in parallel can be obtained, and the light efficiency can also be expected to be improved.

1 is a cross-sectional view of a conventional semiconductor light emitting device.
2 is a plan view of a semiconductor light emitting device according to an embodiment of the present invention.
3 is a cross-sectional view taken at the perforated line AA in Fig.
4 is a cross-sectional view taken at the perforation line BB in Fig.
5 is a plan view of a semiconductor light emitting device according to a comparative example of the present invention.

Advantages and features of the present invention and methods of achieving them will become apparent with reference to the embodiments described in detail below. It should be understood, however, that the invention is not limited to the disclosed embodiments, but is capable of 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, To fully disclose the scope of the invention to those skilled in the art, and the invention is only defined by the scope of the claims. Like reference numerals refer to like elements throughout the specification.

Hereinafter, a semiconductor light emitting device according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. In the following embodiments, a first semiconductor layer is an n-type nitride layer, a second semiconductor layer is a p- Side extending electrode, the second extending electrode is a p-side extending electrode, the first electrode pad is an n-side electrode pad, and the second electrode pad is a p-side electrode pad.

2 is a plan view of a horizontal semiconductor light emitting device according to a first embodiment of the present invention.

As shown in FIG. 2, a contact hole 110 and a trench 120 for isolating the light emitting region are formed to expose the n-type nitride layer through the p-type nitride layer and the active layer. In addition, an n-side extension electrode 111 for electrically connecting the n-type nitride layer exposed by the contact hole 110 is formed on the inside of the contact hole, the p-type nitride layer and the luminescent region separation trench 120 do. The light emitting region separation trench 120 may be formed in a direction perpendicular to the n-side extended electrode 111. The n-side extension electrode 111 is electrically connected to the n-side electrode pad 112, and the contact hole 110 may include two or more of the n-side extension electrodes 111. The two or more contact holes 110 may be regularly formed apart from each other, but their positions are not particularly limited, and they may be arranged in various shapes other than a straight line.

The p-side extended electrode 121 is electrically connected to the p-side electrode pad 122 located in a part of the upper portion of the p-type nitride layer to form a p-side electrode portion. The n-side extension electrode 111 is formed to be electrically insulated from the p-side extension electrode 121.

3 and 4 are cross-sectional views taken along the perforated lines A-A and B-B of FIG. 2 for explaining a more specific configuration.

3, the semiconductor light emitting device of the present invention includes a buffer layer 140, an n-type nitride layer 150, an active layer 160, and a p-type nitride layer 170 stacked in an upper direction of a substrate 130 Respectively.

The substrate 130 may be made of a compound such as SiC, Si, GaN, ZnO, GaAs, GaP, LiAl ₂ O ₃ , BN or AlN. In addition, the buffer layer 140 may be selectively formed to eliminate lattice mismatch between the substrate 130 and the n-type nitride layer 150, and may be formed of AlN or GaN, for example.

The n-type nitride layer 150 is formed on the upper surface of the substrate 130 or the buffer layer 140 and is formed of a nitride doped with an n-type dopant. As the n-type dopant, silicon (Si), germanium (Ge), tin (Sn), or the like may be used. Here, the n-type nitride layer 150 is formed by alternately stacking a first layer made of Si-doped n-type AlGaN or undoped AlGaN and a second layer made of undoped or Si-doped n-type GaN . Of course, the n-type nitride layer 150 can be grown as a single-layer n-type nitride layer, but it can be formed as a laminated structure of the first layer and the second layer, and can function as a carrier- .

The active layer 160 may be composed of a single quantum well structure or a multiple quantum well structure between the n-type nitride layer 150 and the p-type nitride layer 170 and may include electrons flowing through the n-type nitride layer 150 and p Light is generated while the holes flowing through the nitride layer 170 are re-combined. Here, the active layer 160 is a multiple quantum well structure, and the quantum barrier layer and the quantum well layer are Al _x Ga _y In _z N (where x + y + z = 1, 0? X? 1, 1, 0? Z? 1). The active layer 160 having such a structure in which the quantum barrier layer and the quantum well layer are repeatedly formed can suppress spontaneous polarization due to stress and deformation that occur.

The p-type nitride layer 170 is formed of a nitride doped with a p-type dopant. Examples of the p-type dopant include magnesium (Mg), zinc (Zn), cadmium (Cd), and the like. Here, the p-type nitride layer may be formed by alternately stacking a first layer made of Mg-doped p-type AlGaN or undoped AlGaN and a second layer made of undoped or Mg-doped p-type GaN have. Although the p-type nitride layer 170 can be grown as a single p-type nitride layer in the same manner as the n-type nitride layer 150, the p-type nitride layer 170 can be formed as a laminated structure, and can function as a carrier- have.

A contact hole 110 is formed through the p-type nitride layer 170 and the active layer 160 to expose the n-type nitride layer 150. The p-type nitride layer 170 and the active layer 160 are etched to form a light emitting region isolation trench 120.

The contact hole 110 and the trench 120 may be formed through a photoresist or the like. When a photoresist is used as a pattern mask, a photolithography process, an e-beam lithography process, an ion beam lithography process Ion-beam lithography, extreme ultraviolet lithography, proximity X-ray lithography, or nano imprint lithography. In addition, Dry or wet etching may be used.

The n-contact layer 151 may be further formed on the n-type nitride layer 150 exposed by the contact hole 110. The n-contact layer 151 is ohmically contacted with the n-type nitride layer 150 to lower the contact resistance. The n- contact layer 151 may be formed of a transparent conductive oxide, of which the material is In, Sn, Al, Zn, and containing an element such as Ga, for example, ITO, CIO, ZnO, NiO, In ₂ O ₃ It can be formed in any one of them.

An insulating layer 180 is formed on the sidewall of the contact hole 110 to separate the sidewall of the contact hole 110 from the n-side extended electrode 111. The n A portion of the form nitride layer is exposed. The insulating layer 180 extends to the upper portion of the p-type nitride layer 170 and separates the p-type nitride layer 170 from the n-side extended electrode 111. The insulating layer 180 extends to the upper portion of the trench 120, (120) region and the n-side extension electrode (111). The insulating layer 180 may be formed of silicon oxide or silicon nitride and may be formed by a plasma enhanced chemical vapor deposition (PECVD) method, a sputtering method, an MOCVD method, or an e-beam evaporation method.

The n-side extension electrode 111 is formed in the contact hole 110, on the p-type nitride layer 170 and on the trench 120 to electrically connect the n-type nitride layer exposed by the contact hole 110 And may be made of a metal, an alloy, or a metal oxide or other electrically connectable material.

The n-side extending electrode 111 is electrically connected to the n-side electrode pad 112 on the insulating layer 180.

A p-contact layer 171 may be formed under the p-side extending electrode 121 formed apart from the n-side extension electrode 111. The p-contact layer 171 may be formed of a p- The contact resistance is lowered. The p- contact layer 171 may be formed of a transparent conductive oxide, of which the material is In, Sn, Al, Zn, and containing an element such as Ga, for example, ITO, CIO, ZnO, NiO, In ₂ O ₃ It can be formed in any one of them.

4, a buffer layer 140, an n-type nitride layer 150, an active layer 160, a p-type nitride layer 170 (hereinafter, referred to as " And a p-contact layer 171 are sequentially formed on the active layer 160 and the p-type nitride layer 170. The p-side extension electrode 121 is formed on the p- And is electrically connected to the pad 122. In addition, the trench 120 is electrically insulated from the p-side extended electrode 121 by the insulating layer 180. The insulating layer 180 separating the p-contact layer 171 from the sidewalls and the bottom of the trench 120 is formed on the side walls of the n-side extension electrode 111, the side walls of the contact hole 110, and p Or may be formed separately or in connection with an insulating layer 180 that separates the nitride layer 170.

Meanwhile, as shown in the plan view of FIG. 2, the cross-section of the contact hole 110 may be formed in a circle, but is not limited thereto, and may be formed in the shape of a triangle, a quadrangle, or another polygon.

The diameter of the cross-section of the contact hole 110 may be in the range of 1 to 200 μm, preferably 5 to 150 μm. When two or more contact holes are formed, the cross-sectional sizes of the contact holes may be the same or different. have.

The distance between the neighboring contact holes 110 in the one n-side extension electrode 111 may vary according to the cross-sectional area of the entire light emitting device. Preferably, the distance between neighboring contact holes 110 in the n- The distance is adjusted to be in the range of 10 to 500 mu m, more preferably in the range of 50 to 400 mu m.

Meanwhile, the width of the light emitting region separation trench 120 is preferably in the range of 0.5 to 20 탆, preferably 3 to 10 탆.

The width of the n-side extension electrode 111 can be controlled within a range of 1 to 100 μm, preferably 5 to 50 μm, but is not limited thereto. In particular, the width of the n-side extension electrode 111 may be maintained constant. However, as the distance from the n-side electrode pad 112 increases, the width of the n-side extension electrode 111 The width of the n-side extension electrode 111 connecting the contact holes can be increased as the distance from the n-side electrode pad 112 increases in the one n-side extension electrode.

One or more n-side extension electrodes 111 may be electrically connected to the n-side electrode pad 112. At this time, one or more contact holes may be formed in each n-side extension electrode. In particular, the n-side extension electrode 111 may be formed to have not only a linear shape without a bending point but also at least one bending point.

One or more p-side extension electrodes 121 may also be electrically connected to the p-side electrode pads 122. When the two or more p-side extending electrodes 121 are formed, opposite ends not connected to the p-side electrode pad 122 are generally spaced apart from each other, but their ends are connected to each other to form a closed shape . It is obvious to those skilled in the art that the n-side extending electrode 111 may be separated from the n-side extending electrode 111 by the insulating layer even if the ends of the p-side extending electrode 121 are connected to each other.

The light emitting region of the semiconductor light emitting device of the present invention may be divided into a plurality of trenches 120 by the trench 120. When two trenches 120 are formed as shown in FIG. 2, do. As the trench 120 region is formed between the plurality of contact holes 110, each light emitting region includes one or more contact holes 110. The number of the light emitting regions separated and formed by the trenches in one device is not limited, but is preferably divided into 3 to 5 regions, and more preferably, each of the light emitting regions is uniformly separated.

As the light emitting regions are separated, the respective light emitting regions can have the same effect as that of the individual elements connected in parallel by the n-side extending electrode 111 and the p-side extending electrode 121, The current dispersion effect can be expected, and the luminance can be increased by improving the current density.

Hereinafter, the semiconductor light emitting device of the present invention will be described in more detail with reference to the following examples of the present invention.

Example

In order to construct the semiconductor light emitting device as shown in FIGS. 2 to 4, GaN was applied to a nitride layer of a nitride light emitting device on a sapphire substrate, and a general Au based electrode was applied as an extended electrode to obtain a light emitting device.

Comparative Example

A light emitting device having a planar view as shown in FIG. 5 was fabricated by stacking the same nitride-based components as in the example on a sapphire substrate.

The light emission outputs of the light emitting devices of the examples and the comparative examples were measured by applying the same current of 120 mA in the package state, and the results are shown in Table 1 below.

Example Comparative Example Optical power
(mW) 217.2 211

As shown in Table 1, it was confirmed that the light emitting device of the Example improved the light output characteristic by about 3.1% or more as compared with the Comparative Example, and that the light emitting device of the Example exhibited excellent light output characteristics.

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 embodiments, but, on the contrary, is intended to cover various modifications and equivalent arrangements included within the spirit and scope of the appended claims. . Accordingly, the true scope of the present invention should be determined by the following claims.

110: contact hole 111: n-side extended electrode
112: n-side electrode pad 120: light emitting region separation trench
121: p-side extending electrode 122: p-side electrode pad
130: substrate 140: buffer layer
150: n-type nitride layer 151: n- contact layer
160: active layer 170: p-type nitride layer
171: p-contact layer 180: insulating layer

Claims (14)

A semiconductor light emitting device comprising a first semiconductor layer, an active layer and a second semiconductor layer,
A trench separating the second semiconductor layer and the active layer into a plurality of regions and separating the light emitting regions into a plurality of regions;
A current diffusion contact hole formed to expose the first semiconductor layer in a plurality of regions separated by the trench;
A first extension electrode electrically connecting the first semiconductor layer exposed by the current diffusion contact hole; And
And a second extension electrode electrically connected to the second semiconductor layer,
Wherein the first elongated electrode and the second elongated electrode are formed in such a manner that a part of each of the first elongated electrode and the second elongated electrode intersects with the trench.
delete delete The method according to claim 1,
And the area of each of the light emitting regions separated by the trench is uniformly formed.
delete delete The method according to claim 1,
And an insulating layer electrically isolating the first extended electrode from the active layer, the second semiconductor layer, or the trench region, and electrically isolating the second extended electrode from the trench region.
8. The method of claim 7,
Wherein the insulating layer is formed between the second semiconductor layer and the first extended electrode, between the sidewall of the current diffusion contact hole and the first extended electrode, and between the surface of the trench and the first extended electrode. .
The method according to claim 1,
Wherein the first extension electrode is formed in the current diffusion contact hole, the second semiconductor layer, and the trench.
The method according to claim 1,
Wherein at least two of the current diffusion contact holes are included in the first extended electrode.
The method according to claim 1,
Further comprising a first electrode pad electrically connected to the first extension electrode and a second electrode pad electrically connected to the second extension electrode.
The method according to claim 1,
Wherein a diameter of a cross section of the current diffusion contact hole is in a range of 1 to 200 mu m.
The method according to claim 1,
Wherein the current diffusion contact hole has a circular, triangular or rectangular cross section.
The method according to claim 1,
Wherein the width of the trench is in the range of 0.5 to 20 mu m.

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