KR100960276B1 - Iii-nitride semiconductor light emitting device - Google Patents

Abstract

PURPOSE: A third group nitride semiconductor light emitting diode is provided to improve the luminescence of a light emitting diode by reducing the size of a bonding pad and/or the length of a branch electrode in order to decrease the amount of light absorption. CONSTITUTION: A buffer layer(20) is formed on a substrate(10). An n-type third group nitride semiconductor layer(30) is formed on the buffer layer. An active layer(40) is formed on the n-type third group nitride semiconductor layer. A p-type third group nitride semiconductor layer(50) is formed on the active layer. A p-type electrode(60) is formed on the p-type third group nitride semiconductor layer. Branch electrodes(71A-2,71C) are formed on the p-type electrode.

Description

Group III nitride semiconductor light emitting device {III-NITRIDE SEMICONDUCTOR LIGHT EMITTING DEVICE}

The present disclosure relates to a group III nitride semiconductor light emitting device as a whole, and more particularly, to a group III nitride semiconductor light emitting device having improved current spreading.

Here, the group III nitride semiconductor light emitting device has a compound semiconductor layer of Al (x) Ga (y) In (1-xy) N (0 ≦ x ≦ 1, 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1). Means a light emitting device, such as a light emitting diode comprising a, and does not exclude the inclusion of a material consisting of elements of other groups such as SiC, SiN, SiCN, CN or a semiconductor layer of these materials.

This section provides background informaton related to the present disclosure which is not necessarily prior art.

1 is a view illustrating an example of a conventional Group III nitride semiconductor light emitting device, wherein the Group III nitride semiconductor light emitting device is grown on the substrate 100, the buffer layer 200 grown on the substrate 100, and the buffer layer 200. n-type group III nitride semiconductor layer 300, the active layer 400 grown on the n-type group III nitride semiconductor layer 300, p-type group III nitride semiconductor layer 500, p-type 3 grown on the active layer 400 The p-side electrode 600 formed on the group nitride semiconductor layer 500, the p-side bonding pad 700 formed on the p-side electrode 600, the p-type group III nitride semiconductor layer 500 and the active layer 400 are formed. The n-side electrode 800 and the passivation layer 900 are formed on the n-type group III nitride semiconductor layer 300 exposed by mesa etching.

As the substrate 100, a GaN-based substrate is used as the homogeneous substrate, and a sapphire substrate, a SiC substrate, or a Si substrate is used as the heterogeneous substrate. Any substrate may be used as long as the group III nitride semiconductor layer can be grown. When a SiC substrate is used, the n-side electrode 800 may be formed on the SiC substrate side.

Group III nitride semiconductor layers grown on the substrate 100 are mainly grown by MOCVD (organic metal vapor growth method).

The buffer layer 200 is intended to overcome the difference in lattice constant and thermal expansion coefficient between the dissimilar substrate 100 and the group III nitride semiconductor, and US Pat. A technique for growing an AlN buffer layer having a thickness of US Pat. No. 5,290,393 describes Al (x) Ga (1-x) N having a thickness of 10 kPa to 5000 kPa at a temperature of 200 to 900 C on a sapphire substrate. (0 ≦ x <1) A technique for growing a buffer layer is described, and US Patent Publication No. 2006/154454 discloses growing a SiC buffer layer (seed layer) at a temperature of 600 ° C. to 990 ° C., followed by In (x Techniques for growing a Ga (1-x) N (0 <x≤1) layer are described. Preferably, the undoped GaN layer is grown prior to the growth of the n-type group III nitride semiconductor layer 300, which may be viewed as part of the buffer layer 200 or as part of the n-type group III nitride semiconductor layer 300. good.

In the n-type group III nitride semiconductor layer 300, at least a region (n-type contact layer) in which the n-side electrode 800 is formed is doped with impurities, and the n-type contact layer is preferably made of GaN and doped with Si. . U. S. Patent No. 5,733, 796 describes a technique for doping an n-type contact layer to a desired doping concentration by controlling the mixing ratio of Si and other source materials.

The active layer 400 is a layer that generates photons (light) through recombination of electrons and holes, and is mainly composed of In (x) Ga (1-x) N (0 <x≤1), and one quantum well layer (single quantum wells) or multiple quantum wells.

The p-type III-nitride semiconductor layer 500 is doped with an appropriate impurity such as Mg, and has an p-type conductivity through an activation process. U.S. Patent No. 5,247,533 describes a technique for activating a p-type group III nitride semiconductor layer by electron beam irradiation, and U.S. Patent No. 5,306,662 annealing at a temperature of 400 DEG C or higher to provide a p-type group III nitride semiconductor layer. A technique for activating is described, and US Patent Publication No. 2006/157714 discloses a p-type III-nitride semiconductor layer without an activation process by using ammonia and a hydrazine-based source material together as a nitrogen precursor for growing the p-type III-nitride semiconductor layer. Techniques for having this p-type conductivity have been described.

The p-side electrode 600 is provided to supply a good current to the entire p-type group III nitride semiconductor layer 500. US Patent No. 5,563,422 is formed over almost the entire surface of the p-type group III nitride semiconductor layer. A light-transmitting electrode made of Ni and Au in ohmic contact with the p-type III-nitride semiconductor layer 500 is described. US Pat. No. 6,515,306 discloses n on the p-type III-nitride semiconductor layer. A technique is described in which a type superlattice layer is formed and then a translucent electrode made of indium tin oxide (ITO) is formed thereon.

On the other hand, the p-side electrode 600 may be formed to have a thick thickness so as not to transmit light, that is, to reflect the light toward the substrate side, this technique is referred to as flip chip (flip chip) technology. U. S. Patent No. 6,194, 743 describes a technique relating to an electrode structure including an Ag layer having a thickness of 20 nm or more, a diffusion barrier layer covering the Ag layer, and a bonding layer made of Au and Al covering the diffusion barrier layer.

The p-side bonding pad 700 and the n-side electrode 800 are for supplying current and wire bonding to the outside, and US Patent No. 5,563,422 describes a technique in which the n-side electrode is composed of Ti and Al.

The passivation layer 900 is formed of a material such as silicon dioxide and may be omitted.

Meanwhile, the n-type Group III nitride semiconductor layer 300 or the p-type Group III nitride semiconductor layer 500 may be composed of a single layer or a plurality of layers.

FIG. 2 is a view showing an example of the electrode structure disclosed in US Pat. No. 5,563,422, in which the p-side bonding pad 700 and the n-side electrode 800 functioning as the n-side bonding pad are diagonally disposed at the corners of the light emitting device. It is located in the farthest place in the light emitting device improves the current spreading.

3 is a view showing an example of the electrode structure disclosed in US Patent Publication No. 2007-0096115, for the purpose of current diffusion in the light emitting device of a rectangular shape (for example, 600um / 300um horizontal / vertical) The branch electrode 710 and the branch electrode 810 are provided in each of the p-side bonding pad 700 and the n-side electrode 800 that functions as the n-side bonding pad.

4 is a diagram illustrating an example of an electrode structure disclosed in US Pat. No. 6,307,218. As the light emitting device is large in area (for example, 1000 μm / 1000 μm in width and length), the p-side bonding pad 700 may be formed. By providing branch electrodes having equal intervals in the n-side electrode 800 functioning as the n-side bonding pad, current spreading is improved, and in addition, the p-side bonding pad 700 and the n-side electrode 800 are provided for sufficient current supply. There are two).

According to the large area of the light emitting device and high power consumption, the branch electrodes 710 and 810 and the plurality of bonding pads should be introduced for smooth current diffusion in the light emitting device. However, the introduction of the light emitting devices reduces the light emitting area, thereby reducing the light emitting efficiency. In addition, since it includes a reverse function, it is also necessary to improve their design to meet the large area and high power consumption of the light emitting device.

This will be described later in the Specification for Implementation of the Invention.

SUMMARY OF THE INVENTION Herein, a general summary of the present disclosure is provided, which should not be construed as limiting the scope of the present disclosure. of its features).

According to one aspect of the present disclosure, in a Group III nitride semiconductor light emitting device having a long side and a short side as viewed from above, the first Group III nitride semiconductor layer having a first conductivity ; A second group III nitride semiconductor layer having a second conductivity different from the first conductivity; An active layer positioned between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer, and receiving light to generate light; A first bonding pad electrically connected to the first group III nitride semiconductor layer; Two second bonding pads electrically connected to the second group III nitride semiconductor layer at the long sides; and branch electrodes extending along the long sides and limited at both ends by the two second bonding pads. A branch electrode having a distance between the branch electrodes longer than the distance from the first bonding pads to the branch electrodes; and having only one first bonding pad configured to spread current with the second bonding pads. An element is provided. Here, the distance between the first bonding pad and the branch electrode refers to the length of the repair line from the first bonding pad to the branch electrode, and the length of the first bonding pad and the branch electrode is shorter than the distance between both ends of the branch electrode. Means that it is particularly suitable for rectangular light emitting devices.

According to another aspect of the present disclosure (According to one aspect of the present disclosure), in a group III nitride semiconductor light emitting device having a long side and a short side as viewed from above, a first group III nitride semiconductor layer having a first conductivity ; A second group III nitride semiconductor layer having a second conductivity different from the first conductivity; An active layer positioned between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer, and receiving light to generate light; A first bonding pad electrically connected to the first group III nitride semiconductor layer; Two second bonding pads electrically connected to the second group III nitride semiconductor layer at the long sides; A branch electrode electrically connected to two second bonding pads and extending along a long side thereof; And a first additional branch electrode electrically connected to the first bonding pad and extending along the branch electrode, wherein the first bonding pad is located on an opposite side of the branch electrode with respect to the first additional branch electrode. A group III nitride semiconductor light emitting device is provided.

This will be described later in the Specification for Implementation of the Invention.

The present disclosure will now be described in detail with reference to the accompanying drawing (s).

FIG. 5 is a diagram illustrating an example of a group III nitride semiconductor light emitting device according to the present disclosure, and includes two p-side bonding pads 70A, which are formed on a p-side electrode 60, which is a transmissive electrode disposed on the p-type nitride semiconductor layer 50. 70B), an n-side electrode 80 serving as one n-side bonding pad is provided on the n-type nitride semiconductor 30 exposed through etching, and the p-side bonding pad 70A and p are provided. Branch electrodes 71C are provided between the side bonding pads 70B.

In the rectangular light emitting device shown in FIG. 3, branch electrodes may be enlarged and / or the addition of bonding pads may be considered as necessary (large area, increase in power, improvement in current spreading, etc.).

First of all, in view of adding a bonding pad, a method of arranging two bonding pads on the corner of the short side S of a light emitting device (for example, 1000 μm / 550 μm in width / length) may be considered. When supplied to the light emitting device, the distance between the bonding pads is short, and current flows between them, which may not only improve current spreading but also inhibit current spreading. Therefore, it is preferable to arrange two bonding pads at the corner of the long side L of the light emitting device. On the other hand, in relation to which two of the p-side bonding pad and the n-side bonding pad should be provided, since the n-type nitride semiconductor layer on which the n-side bonding pad is placed enables smoother current diffusion than the p-type nitride semiconductor layer, the p-side bonding pad It is preferable to arrange two. If both p-side bonding pads or n-side bonding pads are provided two by one, it may be a problem because the p-side bonding pads and the n-side bonding pads face each other at the short side S. Preferably, the n-side bonding pad or the n-side electrode 80 is located in the middle of the two p-side bonding pads 70A, 70B on the opposite side of the two p-side bonding pads 70A, 70B (see FIG. 5). . At this time, the n-side electrode 80 may be positioned by being slightly pulled into the light emitting device than the position in the embodiment of FIGS. 6 to 8 to be described later.

In view of branch electrode introduction, referring to the light emitting device disclosed in FIG. 3 (eg, 600 μm / 300 μm in width / length), a bonding pad 700 or 800 in which the branch electrode 710 or 810 is located at a short side thereof is described. In the case where the branch electrode 710 or 810 extends along the long side of the light emitting element in the case of facing toward the opposite bonding pad 800 or 700, the resistance increases as the distance from the bonding pad increases, so that the supply of current is smooth. There is no possibility. Accordingly, in the case of the group III nitride semiconductor light emitting device disclosed in FIG. 5, the p-side bonding pads 70A and 70B are positioned on both sides of the branch electrode 71C positioned along the long side L to form a branch electrode 71C. It is formed by equipotential lines. Meanwhile, in the case of the light emitting device shown in FIG. 4 (for example, 1000 μm / 1000 μm in width / length), branch electrodes are formed between the bonding pads. And the current diffusion in the light emitting device is made by branch electrodes extending at uniform intervals toward each other in interdigitated shape, and the branch electrodes located between the bonding pads are connected to these interdigitated branch electrodes. It can be seen that it is provided for supplying a current.

FIG. 6 is a view showing another example of the group III nitride semiconductor light emitting device according to the present disclosure, in addition to the p-side bonding pads 70A and 70B, the n-side bonding pad or the n-side electrode 80, and the branch electrode 71C. The branch electrode 71A-1 is provided along the short side S, and the branch electrodes 81-1, 81-2, 81-3, 81-4 are formed from the n-side electrode 80. FIG. . Branch electrodes 71A-2, 71A-3, 71C-2 may be further provided as necessary (larger area, increased power, improved current spreading, etc.). Preferably, the branch extending along the short side S and the gap a between the branch electrode 71C and the branch electrode 81-2 extending along the long side L for uniform current spreading. The spacing c between the p-side bonding pad 70A and the branch electrode 81-3 is larger than the spacing b between the electrode 71A-1 and the branch electrode 81-4. This is to prevent current dropping around the p-side bonding pad 70A. The description of the unexplained symbols 50 and 60 will be omitted.

FIG. 7 is a diagram illustrating an example of an actual measured photograph of the light emitting device disclosed in FIG. 6. In order to explain the principle according to the present disclosure, an experiment result when a current is supplied to only one of the p-side bonding pads is shown. It can be seen that the light emission of the left p-side bonding pad side to which no current is supplied is weak, and the overall uniform light emission can be confirmed from the right p-side bonding pad side to which the current is supplied. From this, two n-side bonding pads positioned on the long side and one n-side bonding pad positioned on the opposite side (and / or one n-side positioned on the opposite side to the branch electrode connecting the two p-side bonding pads) It can be seen that a uniform light emission can be obtained by using a bonding pad.

FIG. 8 is a view showing another example of the group III nitride semiconductor light emitting device according to the present disclosure, and is provided on the p-side bonding pads 70A and 70B, the n-side bonding pad or the n-side electrode 80, and the branch electrode 71C. In addition, a branch electrode 81A extending from the n-side electrode 80 along the branch electrode 71C is further provided. By introducing the branch electrode 81A which is facing the branch electrode 71C, the current spreading in the long side L direction in the light emitting element can be more smoothly performed. The branch electrode 81A does not necessarily need to be positioned at the center of the light emitting device, and the branch electrode 81B may be used depending on the positions of the branch electrode 81A and the n-side electrode 80. When the light emitting device has a large area, the branch electrode 71A-1 extending along the short side S is provided or branched together for smooth current spreading on the opposite side of the branch electrode 71C based on the branch electrode 81A. The electrode 71A-2 may be provided. Preferably, the sum of the lengths of the branch electrodes 71A-1 and the branch electrodes 71A-2 is shorter than the length of the branch electrodes 71C. The description of the unexplained symbols 50 and 60 will be omitted.

FIG. 9 is a diagram illustrating an example of a cross section taken along the AA line of FIG. 8, wherein the substrate 10, the buffer layer 20 grown on the substrate 10, and the n-type group III nitride semiconductor grown on the buffer layer 20 are illustrated in FIG. Layer 30, active layer 40 grown on n-type Group III nitride semiconductor layer 30, p-type Group III nitride semiconductor layer 50 grown on active layer 40, p-type Group III nitride semiconductor layer 50 P-side electrode 60 formed on the p-type electrode 60, branch electrodes 71A-2 and 71C formed on the p-side electrode 60, and the p-type group III nitride semiconductor layer 50 and the active layer 40 are mesa-etched. An n-side electrode 80 formed on the exposed n-type Group III nitride semiconductor layer 30 is formed.

Various embodiments of the present disclosure will be described below.

And (1) a first additional branch electrode electrically connected to the first bonding pad and extending along the branch electrode. The branch electrode 81-2 of FIG. 6 and the branch electrode 81A of FIG. 8 may be examples of the first additional branch electrode.

(2) a second additional branch electrode 81-3 connected to the first additional branch electrode 81-2 and facing one of the two second bonding pads; A group III nitride semiconductor light emitting element, characterized in that the spacing (a) between the branch electrode and the branch electrode is smaller than the spacing (b) between the second additional branch electrode and the branch electrode.

(3) third additional branch electrodes 81-1 and 81B connected to the first additional branch electrodes 81-2 and 81A and extending from the first bonding pad toward the branch electrodes. Group III nitride semiconductor light emitting device.

(4) Fourth additional branch electrodes 71A-1, 71A-1, 71A-2 or 71A-1, 71A-2, 71A- connected to one of the two second bonding pads, one end of which is open; 3); Group III nitride semiconductor light emitting device comprising a.

(5) A group III nitride semiconductor light emitting element comprising: a fifth additional branch electrode 71C-2 electrically connected to the branch electrode 71C, and one end of which is open.

delete

(6) The group III nitride semiconductor light emitting element, wherein the light emitting element is rectangular when viewed from above. This corresponds to the most preferable example of the group III nitride semiconductor light emitting device according to the present disclosure, for example, a light emitting device having a width / length of 1000um / 550um. The effect of the foot opening becomes greater when the length difference between the long side and the short side becomes larger, and the technical idea according to the present disclosure will be more evident when the length of the rectangular long side is 1.5 times larger than the length of the short side. .

(7) A Group III nitride semiconductor light emitting element, wherein the length of the fourth additional branch electrode is shorter than the length of the branch electrode.

(8) A group III nitride semiconductor light emitting element, wherein an area of the first bonding pad is smaller than that of two second bonding pads.

According to one group III nitride semiconductor light emitting device according to the present disclosure, it is possible to improve the current spreading of the light emitting device.

In addition, according to another group III nitride semiconductor light emitting device according to the present disclosure, light emission of the light emitting device can be improved. This can be done in particular by reducing the size of the bonding pads and / or the length of the branch electrodes to reduce the amount of light they absorb.

In addition, according to another group III nitride semiconductor light emitting device according to the present disclosure, by arranging the bonding pads along a long side, it is possible to improve the problems caused by current driving therebetween.

In addition, according to another group III nitride semiconductor light emitting device according to the present disclosure, current diffusion is performed by using branch electrodes positioned between bonding pads, thereby improving the problem of using branch electrodes having open ends. Will be.

In addition, according to another group III nitride semiconductor light emitting device according to the present disclosure, by arranging two p-side bonding pads and one n-side bonding pad, light is emitted by the bonding pads despite the introduction of additional bonding pads. Absorption can be reduced.

In addition, according to another Group III nitride semiconductor light emitting device according to the present disclosure, by placing one n-side bonding pad in a substantially central portion facing two p-side bonding pads, the n-side bonding pad and the two p-side Uniform current spreading can be achieved between the bonding pads.

1 is a view showing an example of a conventional group III nitride semiconductor light emitting device,

2 is a view showing an example of an electrode structure disclosed in US Patent No. 5,563,422;

3 is a view showing an example of the electrode structure disclosed in US Patent Publication No. 2007-0096115,

4 is a view showing an example of an electrode structure disclosed in US Pat. No. 6,307,218;

5 is a view showing an example of a group III nitride semiconductor light emitting device according to the present disclosure;

6 is a view showing another example of the group III nitride semiconductor light emitting device according to the present disclosure;

7 is a view showing an example of an actual measurement photo of the light emitting device disclosed in FIG.

8 is a view showing another example of a group III nitride semiconductor light emitting device according to the present disclosure;

9 is a view showing an example of a cross section taken along the line A-A of FIG.

Claims (16)

In the group III nitride semiconductor light emitting device having a long side and a short side as viewed from above, A first group III nitride semiconductor layer having a first conductivity; A second group III nitride semiconductor layer having a second conductivity different from the first conductivity; An active layer positioned between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer, and receiving light to generate light; A first bonding pad electrically connected to the first group III nitride semiconductor layer; Two second bonding pads electrically connected to the second group III nitride semiconductor layer at the long sides; and A branch electrode extending along the long side and limited at both ends by two second bonding pads, wherein the distance between the two ends is longer than the distance from the first bonding pad to the branch electrode; A group III nitride semiconductor light-emitting device, characterized in that it has only one first bonding pad for current diffusion to the second bonding pad of the. The method according to claim 1, And a first additional branch electrode electrically connected to the first bonding pad and extending along the branch electrode. The method according to claim 2, A second additional branch electrode connected to the first additional branch electrode and facing one of the two second bonding pads, wherein the spacing between the first additional branch electrode and the branch electrode is equal to the second additional branch electrode; A group III nitride semiconductor light emitting device characterized in that it is smaller than the distance between the branch electrode and the branch electrode. The method according to claim 2, And a third additional branch electrode connected to the first additional branch electrode and extending from the first bonding pad toward the branch electrode. The method according to claim 1, And a fourth additional branch electrode connected to one of the two second bonding pads, one end of which is open. The method according to claim 2, And a fourth additional branch electrode connected to one of the two second bonding pads, one end of which is open. The method according to claim 3, And a fourth additional branch electrode connected to one of the two second bonding pads, one end of which is open. The method of claim 7, wherein And a fifth additional branch electrode electrically connected to the branch electrode and having one end open. The method according to claim 4, And a fourth additional branch electrode connected to one of the two second bonding pads, one end of which is open. delete In the group III nitride semiconductor light emitting device having a long side and a short side as viewed from above, A first group III nitride semiconductor layer having a first conductivity; A second group III nitride semiconductor layer having a second conductivity different from the first conductivity; An active layer positioned between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer, and receiving light to generate light; A first bonding pad electrically connected to the first group III nitride semiconductor layer; Two second bonding pads electrically connected to the second group III nitride semiconductor layer at the long sides; A branch electrode electrically connected to two second bonding pads and extending along a long side thereof; And, And a first additional branch electrode electrically connected to the first bonding pad and extending along the branch electrode, wherein the first bonding pad is positioned on an opposite side of the branch electrode with respect to the first additional branch electrode. Group III nitride semiconductor light emitting device. delete The method according to claim 1, The light emitting device is a group III nitride semiconductor light emitting device, characterized in that the rectangular shape when viewed from above. The method of claim 13, A group III nitride semiconductor light-emitting device, characterized in that the length of the rectangular long side is 1.5 times or more larger than the length of the short side. The method according to claim 5, A group III nitride semiconductor light emitting element, wherein the length of the fourth additional branch electrode is shorter than the length of the branch electrode. The method according to claim 1, A group III nitride semiconductor light emitting device, characterized in that the area of the first bonding pad is smaller than the area of the two second bonding pads.

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