KR20140049877A - 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 element comprising a light emitting region separation trench and a contact hole structure. The semiconductor light emitting element according to the present invention can widen an effective light emitting area by evenly dispersing a flowing current through a semiconductor layer. In addition, each light emitting region is separated by the light emitting region separation trench, thereby having an effect similar to an effect caused by the parallel connection of elements, and improving optical efficiency.

Description

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

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a semiconductor light emitting device having improved luminance characteristics, including a light emitting region isolation trench and a contact hole structure.

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.

Accordingly, the present inventors have conducted research and efforts to develop a semiconductor light emitting device having a structure capable of exhibiting an excellent current dispersion effect, and as a result, the first semiconductor layer exposed inside the contact hole and the upper portion of the second semiconductor layer formed to expose the first semiconductor layer. A first extension electrode that electrically connects the second electrode, a trench that can separate a plurality of light emitting regions, a gap between the second semiconductor layer and the first extension electrode, between the sidewall of the contact hole and the first extension electrode; The present invention has been completed by discovering that an insulating layer is formed between the surface of the trench and the first extension electrode to form a semiconductor light emitting device having a plurality of light emitting regions, thereby maximizing current dispersion to improve luminance.

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

The semiconductor light emitting device of the present invention for achieving the above object comprises a first semiconductor layer, an active layer and a second semiconductor layer, it characterized in that it comprises a contact hole and trench for current diffusion.

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

In addition, the semiconductor light emitting device of the present invention is formed such that the current diffusion contact hole exposes the first semiconductor layer, and a first extension electrically connecting the first semiconductor layer exposed by the current diffusion contact hole. And an second extension electrode electrically connected to the electrode and the second semiconductor layer.

In addition, the semiconductor light emitting device of the present invention includes an insulating layer electrically insulating the first extension electrode and the active layer, the second semiconductor layer or the trench region, and electrically insulating the second extension electrode and the trench region. The insulating layer may be formed between the second semiconductor layer and the first extension electrode, between the sidewall of the current diffusion contact hole and the first extension electrode, and between the surface of the trench and the first extension electrode.

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

In addition, as the respective light emitting regions are separated by the light emitting region isolation trenches, the same effects as those of individual elements connected in parallel can be obtained, and the light efficiency can 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 embodiment, the first semiconductor layer is an n-type nitride layer, and the second semiconductor layer is a p-type nitride. The layer and the first extension electrode are n-side extension electrode, the second extension electrode is p-side extension electrode, the first electrode pad is n-side electrode pad, and the second electrode pad is 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 light emitting region isolation trench 120 formed through the p-type nitride layer and the active layer to expose the n-type nitride layer are formed. In addition, an n-side extension electrode 111 electrically connecting the n-type nitride layer exposed by the contact hole 110 to the inside of the contact hole, the p-type nitride layer and the light emitting region isolation trench 120 is included. do. The emission region isolation trench 120 may be formed in a vertical direction of the n-side extension electrode 111. The n-side extension electrode 111 may be electrically connected to the n-side electrode pad 112, and two or more contact holes 110 may be included in one n-side extension electrode 111. The two or more contact holes 110 may be regularly spaced apart from each other, but the position at which the two or more contact holes 110 are formed is not particularly limited and may be arranged in various forms rather than in a straight line.

The p-side extension electrode 121 is electrically connected to the p-side electrode pad 122 positioned on a part of the upper portion of the p-type nitride layer to form the p-side electrode part. 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.

The 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. In addition, 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 using a photoresist as a pattern mask, photo-lithography, e-beam lithography, and ion beam lithography Ion-beam Lithography, Extreme Ultraviolet Lithography, Proximity X-ray Lithography, or Nano imprint lithography, or the like, may be formed. The dry or wet etching may be used.

An n-contact layer 151 may be further included on the n-type nitride layer 150 exposed by the contact hole 110. The n-contact layer 151 is ohmic contacted to the n-type nitride 150 to lower the contact resistance. The n-contact layer 151 may be made of a transparent conductive oxide, and the material may include elements such as In, Sn, Al, Zn, Ga, and the like, for example, of ITO, CIO, ZnO, NiO, and In ₂ O ₃ . It can be formed of either.

In addition, an insulating layer 180 is formed on the sidewalls of the contact holes 110 to separate the sidewalls of the contact holes 110 from the n-side extension electrode 111 and are exposed by the contact holes 110. Part of the form nitride layer is exposed. The insulating layer 180 extends over the p-type nitride 170 to separate the p-type nitride layer 170 from the n-side extension electrode 111, and extends over the trench 120 to form a trench. The area 120 is spaced apart from 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, a 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 n-type nitride layer exposed by the contact hole 110. It serves to connect, it may be made of a material capable of electrical connection, such as metal, alloy or metal oxide.

In addition, the n-side extension electrode 111 is electrically connected to the n-side electrode pad 112 present on the insulating layer 180.

A p-contact layer 171 may be formed below the p-side extension electrode 121 formed to be spaced apart from the n-side extension electrode 111, and the p-contact layer 171 may be a p-type nitride 170. Ohmic contact reduces contact resistance. The p-contact layer 171 may be made of a transparent conductive oxide, and the material may include elements such as In, Sn, Al, Zn, Ga, and the like, for example, of ITO, CIO, ZnO, NiO, and In ₂ O ₃ . It can be formed of either.

As shown in FIG. 4, the buffer layer 140, the n-type nitride layer 150, the active layer 160, and the p-type nitride layer 170 are disposed below the p-side extension electrode 121 in the upper direction of the substrate 130. ) And p-contact layer 171 are sequentially formed, and a trench 120 region where the active layer 160 and the p-type nitride layer 170 are etched is also formed, and the p-side extension electrode 121 is a p-side electrode. It is electrically connected to the pad 122. In addition, the trench 120 is electrically insulated from the p-side extension electrode 121 by the insulating layer 180. As shown in FIG. 3, the insulating layer 180 which separates the p-contact layer 171 from the sidewalls and the bottom surface of the trench 120 includes the sidewalls of the n-side extension electrode 111 and the contact hole 110 and p. The nitride layer 170 may be formed to be connected to or separated from the insulating layer 180 spaced apart from each other.

On the other hand, as shown in the plan view of Figure 2, the cross section of the contact hole 110 may be formed as a circle, but is not limited to this, it may be formed in the form of a triangle, a square or other polygons.

In addition, the diameter of the cross section of the contact hole 110 may be formed in the range of 1 to 200 μm, preferably 5 to 150 μm, and when two or more contact holes are formed, the size of the cross sections may be all the same or different. have.

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

On the other hand, the width of the light emitting region separation trench 120 is preferably formed in the range of 0.5 to 20 ㎛, preferably 3 to 10 ㎛.

In addition, the width of the n-side extension electrode 111 may be adjusted within the 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 while being constant, but as the distance from the n-side electrode pad 112 increases, the width of the n-side extension electrode 111 connecting the contact holes is increased. The width of the n-side extension electrode 111 connecting the contact hole may increase as the distance from the n-side electrode pad 112 increases in the one n-side extension electrode.

One or two or more n-side extension electrodes 111 may be electrically connected to the n-side electrode pad 112, and at least one contact hole may be formed in each of the n-side extension electrodes. In particular, the n-side extension electrode 111 may be formed to have one or more bending points as well as a straight shape having no bending points.

One or more p-side extension electrodes 121 may also be electrically connected to the p-side electrode pad 122. When the two or more p-side extension electrodes 121 are formed, opposite ends that are not connected to the p-side electrode pad 122 are generally formed to be spaced apart from each other, but the ends may be connected to each other to form a closed figure. . As described above, even if the ends of the p-side extension electrode 121 are connected to each other, the n-side extension electrode 111 may be spaced apart by an insulating layer.

The light emitting regions of the semiconductor light emitting device of the present invention may be divided into a plurality of by the trench 120. As shown in FIG. 2, when two trenches 120 are formed, the light emitting regions are divided into three regions. do. As the trench 120 regions are formed between the plurality of contact holes 110, each light emitting region may include one or more contact holes 110. The number of light emitting regions separated and formed by the trench in one device is not particularly limited, but is preferably divided into three to five regions, and more preferably, so that the area of each of the light emitting regions is uniform.

As the light emitting regions are separated, the respective light emitting regions may have the same effect as if the individual elements are connected in parallel by the n-side extension electrode 111 and the p-side extension electrode 121, and the plurality of contact holes Current dispersion effect can be expected and brightness can be increased by improving 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

2 to 4, GaN was applied as a nitride layer of a nitride light emitting device to a sapphire substrate, and a general Au-based electrode was applied as an extension electrode to obtain a light emitting device.

Comparative Example

A light emitting device was manufactured by stacking the same nitride-based component as in Example on a sapphire substrate, but having a plan view as illustrated in FIG. 5.

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, the light emitting device of the embodiment was improved by about 3.1% or more light output compared to the comparative example, it was confirmed that the light emitting device of the embodiment can exhibit 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 extension electrode
112: n-side electrode pad 120: trench for separating light emitting region
121: p-side extension 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 semiconductor light emitting device comprising a current spreading contact hole and a trench.
The method of claim 1,
A plurality of light emitting regions are separated by the trench.
3. The method of claim 2,
And at least one contact hole is present in the light emitting region separated by the trench.
3. The method of claim 2,
And the area of each of the light emitting regions separated by the trench is formed uniformly.
The method of claim 1,
The current diffusion contact hole is formed to expose the first semiconductor layer.
6. The method of claim 5,
A first extension electrode electrically connecting the first semiconductor layer exposed by the current diffusion contact hole;
And a second extension electrode electrically connected to the second semiconductor layer.
The method according to claim 6,
And an insulating layer electrically insulating between the first extension electrode and the active layer, the second semiconductor layer, or the trench region, and electrically insulating the second extension electrode and the trench region.
8. The method of claim 7,
And the insulating layer is formed between the second semiconductor layer and the first extension electrode, between the sidewall of the current spreading contact hole and the first extension electrode, and between the surface of the trench and the first extension electrode. .
The method according to claim 6,
And the first extension electrode is formed in the current diffusion contact hole, the second semiconductor layer, and the trench.
The method according to claim 6,
And at least two contact diffusion holes for current spreading in the first extension electrode.
The method according to claim 6,
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 of claim 1,
The diameter of the cross section of the current diffusion contact hole is in the range of 1 ~ 200 ㎛ semiconductor light emitting device.
The method of claim 1,
A cross section of the current spreading contact hole has a circular, triangular or rectangular shape.
The method of claim 1,
The width of the trench is a semiconductor light emitting device, characterized in that in the range of 0.5 ~ 20 ㎛.

Images