KR20120100359A - Iii-nitride semiconductor light emitting device - Google Patents

Abstract

PURPOSE: An III group nitride semiconductor light emitting diode is provided to improve photonic efficiency by minimizing the area of an active layer creating light in the process forming an electrode to be diminished. CONSTITUTION: A buffer layer is formed on a substrate(111). An n-type III group nitride semiconductor layer(113) is formed on the buffer layer. An active layer(114) is formed on the n-type III group nitride semiconductor layer. A p-type III group nitride semiconductor layer(115) is formed on the active layer. A p-side electrode(116) is formed on the p-type III group nitride semiconductor layer. A p-side bonding pad(117) is formed on the p-side electrode. An n-side electrode is formed the -type III group nitride semiconductor layer which is exposed by etching the p-type III group nitride semiconductor layer and the active layer.

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, and more particularly, to a laminated structure of a group III nitride semiconductor layer forming a group III nitride semiconductor light emitting device.

Herein, the background art relating to the present disclosure is provided, and these are not necessarily meant to be known arts.

In general, the group 3-5 compound semiconductor light emitting device refers to a semiconductor device that generates light through recombination of electrons and holes, Al (x) Ga (y) In (1-xy) N (0≤x≤1 , Group III nitride semiconductor light emitting device comprising a compound of 0 ≦ y ≦ 1, 0 ≦ x + y ≦ 1), GaAs semiconductor light emitting device for red light emission, GaP semiconductor light emitting device for green light emission, etc. For example.

1 is a view showing an example of a conventional group III nitride semiconductor light emitting device, the group III nitride semiconductor light emitting device 10 is a substrate 11, a buffer layer 12, a buffer layer 12 grown on the substrate 11 An n-type group III nitride semiconductor layer 13 grown thereon, an active layer 14 grown on the n-type group III nitride semiconductor layer 13, a p-type group III nitride semiconductor layer 15 grown on the active layer 14, p-side electrode 16 formed on p-type Group III nitride semiconductor layer 15, p-side bonding pad 17 formed on p-side electrode 16, p-type Group III nitride semiconductor layer 15 and active layer ( 14 includes an n-side electrode 18 and a passivation layer 19 formed on the n-type Group III nitride semiconductor layer 13 exposed by mesa etching.

As the substrate 11, 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 18 may be formed on the SiC substrate side.

Group III nitride semiconductor layers grown on the substrate 11 are mainly grown by MOCVD (organic metal vapor growth method).

The buffer layer 12 is intended to overcome the difference in lattice constant and thermal expansion coefficient between the dissimilar substrate 11 and the group III nitride semiconductor, and US Pat. No. 5,122,845 shows a sapphire substrate on a sapphire substrate at a temperature of 380 캜 to 800 캜 at 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.

Meanwhile, a undoped GaN layer is grown prior to the growth of the n-type group III nitride semiconductor layer 13, which may be viewed as part of the buffer layer 12 or as part of the n-type group 3 nitride semiconductor layer 13.

In the n-type group III nitride semiconductor layer 13, at least a region (n-type contact layer) in which the n-side electrode 18 is formed is doped with an impurity, 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 14 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 15 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 growth of the p-type III-nitride semiconductor layer. Techniques for having this p-type conductivity have been described.

The p-side electrode 16 is provided to ensure good current supply to the entire p-type group III nitride semiconductor layer 15, and 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 15 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 16 can 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 for 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 17 and the n-side electrode 18 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 protective film 19 is formed of a material such as silicon dioxide, and may be omitted.

Meanwhile, in order to improve light efficiency and electrical characteristics of the group III nitride semiconductor light emitting device, a technique of manufacturing a vertical group III nitride semiconductor light emitting device by separating the substrate 11 from the group III nitride semiconductor layers through laser or wet etching. This was introduced.

In addition, as the demand for a large-area group III nitride semiconductor light emitting device increases, a technology including branch electrodes extending from the p-side bonding pad 17 or the n-side electrode 18 is introduced to spread current. have.

The present disclosure aims to provide a group III nitride semiconductor light emitting device having greatly improved light efficiency by minimizing the reduction of the area of the active layer where light is generated in the process of forming an electrode.

In order to solve the above problems, according to an aspect of the present disclosure, 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 interposed between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer, wherein light is generated by recombination of electrons and holes; A first contact hole passing through the first group III nitride semiconductor layer and the active layer and reaching the second group III nitride semiconductor layer; A first electrode electrically connected to the first group III nitride semiconductor layer; And a second electrode provided on the first group III nitride semiconductor layer, the second electrode being electrically connected to the second group III nitride semiconductor layer through the first contact hole and electrically insulated from the first group III nitride semiconductor layer. A group III nitride semiconductor light emitting device comprising a is provided.

Also, a second contact hole penetrating through the first group III nitride semiconductor layer and the active layer and reaching the second group III nitride semiconductor layer; And a second sub-electrode provided on the first group III nitride semiconductor layer and electrically connected to the second group III nitride semiconductor layer through the second contact hole and electrically insulated from the first group III nitride semiconductor layer. And, a second sub-electrode provided to be electrically connected to the second electrode.

Further, it extends long from the second electrode, is provided on the first group III nitride semiconductor layer, and electrically connected to the second sub-electrode and the second electrode, and provided to be electrically insulated from the first group III nitride semiconductor layer. Branch electrode; characterized in that it further comprises.

In addition, a plurality of second sub-electrodes electrically connected to the second group III nitride semiconductor layer through the second contact hole and the second contact hole may be provided, and the plurality of second sub-electrodes may be electrically connected to the second electrode. It is characterized by.

The at least one second sub electrode may be electrically connected to the second electrode via another second sub electrode.

In addition, the at least two second sub-electrodes may be electrically connected to the second electrode via one other second sub-electrode.

In addition, a conductive material layer provided in the first contact hole and in contact with the second electrode and the second group III nitride semiconductor layer, respectively; And an insulating material layer that insulates the conductive material layer from the first group III nitride semiconductor layer and the active layer, wherein the insulating material layer is interposed between the conductive material layer and the first group III nitride semiconductor layer and between the conductive material layer and the active layer in the first contact hole. The insulating material layer is characterized in that it further comprises.

In addition, the conductive material layer is in contact with at least four surfaces of the second group III nitride semiconductor layer.

In addition, irregularities are provided on the surface of the second group III nitride semiconductor layer in contact with the conductive material layer.

In addition, the first contact hole may be provided such that the cross-sectional area of the first contact hole increases from the first group III nitride semiconductor layer toward the second group III nitride semiconductor layer.

According to an example of the group III nitride semiconductor light emitting device according to the present disclosure, since the electrodes are connected through the contact holes, the area of the active layer is reduced by the mesa etching as before, thereby improving the problem of low light efficiency.

In addition, since the plurality of sub-electrodes electrically connected to the electrodes are connected to the semiconductor layer by the plurality of contact holes, it is possible to control the current to be uniformly spread.

Therefore, the light efficiency can be improved and the driving voltage can be lowered.

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 a group III nitride semiconductor light emitting device according to the present disclosure;
3 is an enlarged view of A of FIG. 2;
4 is a view showing another example of the group III nitride semiconductor light emitting device according to the present disclosure;
5 is a view illustrating II of FIG. 4,
6 is a view illustrating optical characteristics of the group III nitride semiconductor light emitting device of FIG. 4;
7 and 8 show still another example of the group III nitride semiconductor light emitting device according to the present disclosure;
9 is a view showing various modifications of FIG.

Hereinafter, various embodiments of the group III nitride semiconductor light emitting device according to the present disclosure will be described in detail with reference to the accompanying drawings.

2 is a diagram illustrating an example of a group III nitride semiconductor light emitting device according to the present disclosure, and FIG. 3 is an enlarged view of A of FIG. 2.

2 and 3, the group III nitride semiconductor light emitting device 100 according to the present disclosure is formed on the substrate 111 and the substrate 111, like the group III nitride semiconductor light emitting device 10 illustrated in FIG. 1. A buffer layer 112 to be grown, an n-type group III nitride semiconductor layer 113 grown on the buffer layer 112, an active layer 114 grown on the n-type group III nitride semiconductor layer 113, and grown on the active layer 114 The p-type electrode 116 and the p-type electrode 116 formed on the p-type group III nitride semiconductor layer 115 and the p-type group III nitride semiconductor layer 115 (or the p-type group III nitride semiconductor layer 115). P-side bonding pads 117 formed on the back side).

Accordingly, the substrate 111, the buffer layer 112, the n-type Group III nitride semiconductor layer 113, the active layer 114, the p-type Group III nitride semiconductor layer 115, the p-side electrode 116 and the p-side bonding pad The detailed description of 117 is replaced with the foregoing description.

However, in the present example, the n-side electrode 121 is positioned on the p-type Group III nitride semiconductor layer and is provided to be electrically connected to the n-type Group III nitride semiconductor layer 113.

For the electrical connection between the n-side electrode 121 and the n-type Group III nitride semiconductor layer 113, the p-type Group III nitride semiconductor layer 115 and the active layer (from the upper surface of the p-type Group III nitride semiconductor layer 115) A contact hole 123 penetrating through 114 and reaching the n-type group III nitride semiconductor layer 113 is provided.

The conductive material layer 127 in contact with the n-side electrode 121 and the n-type group III nitride semiconductor layer 113 is provided inside the contact hole 123.

The conductive material layer 127 may be formed of Ag and Al to prevent absorption of light generated and emitted from the active layer 114.

In addition, in order to prevent the n-side electrode 121 from being energized with the p-type group III nitride semiconductor layer 115 and the active layer 114 through the conductive material layer 127, that is, the inner surface of the contact hole 123, that is, the conductive material. An insulating material layer 125 is interposed between the material layer 127 and the p-type group III nitride semiconductor layer 115 and between the conductive material layer 127 and the active layer 114.

In addition, since a bonding wire (for example, Au) having a diameter of about 70 nm connected to an external power source (not shown) is bonded to the n-side electrode 121, the diameter of the n-side electrode 121 may correspond to the contact hole 123. It is provided larger than the diameter of.

Therefore, electrical insulation is required between the lower surface of the n-side electrode 121 and the p-type group III nitride semiconductor layer 115 (or the p-side electrode 116), and the insulating material layer 125 is formed of the n-side electrode ( It is also necessary to be interposed between the lower surface of 121 and the p-type group III nitride semiconductor layer 115 (or the p-side electrode 116).

The insulating material layer 125 may be formed of SiO ₂ or SiN _x .

The process of interposing the insulating material layer 125 between the conductive material layer 127 and the p-type group III nitride semiconductor layer 115 and between the conductive material layer 127 and the active layer 114 includes an insulating material. After the layer 125 is applied (or deposited) to the entire inner surface of the contact hole 123 including the n-type group III nitride semiconductor layer 113, the insulating material is exposed to expose the n-type group III nitride semiconductor layer 113. It is preferable to proceed with the order of removing (or etching) the layer 125 and forming the conductive material layer 127 inside the contact hole 123.

Here, the upper surface of the conductive material layer 127 provided in the contact hole 123 may be provided to have a groove recessed toward the inner side of the contact hole 123.

This is because the problem that the n-side electrode 121 is peeled off can be prevented by increasing the contact area between the n-side electrode 121 and the conductive material layer 127.

Thus, according to the Group III nitride semiconductor light emitting device 100 according to the present example, the n-type Group III nitride semiconductor layer is used for electrical connection between the n-side electrode 121 and the n-type Group III nitride semiconductor layer 113. The mesa etching process of removing the p-type group III nitride semiconductor layer 115 and the active layer 114 to expose the 113 is removed.

Therefore, since the area of the active layer 114 in which light is generated is improved, the light efficiency is improved.

4 is a view showing another example of a group III nitride semiconductor light emitting device according to the present disclosure, FIG. 5 is a view showing II of FIG. 4, and FIG. 6 is a view showing optical characteristics of the group 3 nitride semiconductor light emitting device of FIG. 4. .

4 to 6, the group III nitride semiconductor light emitting device 100 according to the present example is substantially the same as the example illustrated in FIGS. 1 to 2, but in that a plurality of contact holes 123 are provided. There is a difference.

As described above, the plurality of contact holes 123 include a conductive material layer 127 and an insulating material layer 125 therein, and the conductive material layer 127 provided in each of the plurality of contact holes 123. Is provided to be electrically connected to the n-side electrode 121.

To this end, branch electrodes 121a which extend from the n-side electrode 121 and are respectively bonded to the conductive material layers 127 provided in the plurality of contact holes 123 are provided.

Here, the branch electrodes 121a are respectively bonded to the conductive material layers 127 provided in the plurality of contact holes 123 to form a plurality of sub-electrodes, and portions not bonded to the conductive material layer 127 are p. The insulating material layer 125 is interposed on the lower surface of the type III group nitride semiconductor layer 115 (or the p-side electrode 116).

As a result, the current input through the n-side electrode 121 can be more uniformly spread over the n-type Group III nitride semiconductor layer 113.

On the other hand, for a more uniform distribution of the current, it is preferable that the top electrode 117a extending from the p-side bonding pad 117 is further provided.

Meanwhile, in order to improve the bonding force between the conductive material layer 127 and the branch electrode 121a provided in each of the plurality of contact holes 123, the conductive material layer 127 is recessed in the direction of the contact hole 123 on the upper surface. It is preferable to be provided to form a groove.

FIG. 6 illustrates the driving voltage Vf and the light output Pout of the group III nitride semiconductor light emitting device 100 illustrated in FIG. 4 in comparison with the group III nitride semiconductor light emitting device 10 illustrated in FIG. 1. According to the group III nitride semiconductor light emitting device 100 according to the present example, it can be seen that the light output is increased by 3.3% without increasing the driving voltage Vf.

7 and 8 illustrate still another example of the group III nitride semiconductor light emitting device according to the present disclosure.

7 and 8, in the group III nitride semiconductor light emitting device 100 according to the present example, the branch electrodes 121a extending from the n-side electrode 121 are provided in each of the plurality of contact holes 123. It is bonded to the conductive material layer 127 in turn, and is insulated from the p-type group III nitride semiconductor layer 115 (or the p-side electrode 116).

In addition, two branch electrodes 123 bonded to different contact holes 123 are provided to be connected to the n-side electrode 121 via one contact hole 123.

This makes it possible to more uniformly improve the distribution of the current.

9 is a diagram illustrating various modified examples of FIG. 3.

Referring to FIG. 9, in the Group III nitride semiconductor light emitting device 100 according to the present disclosure, the contact hole 123 may be strengthened so that the bonding between the conductive material layer 127 and the n type Group III nitride semiconductor layer 113 is enhanced. Is preferably provided as shown in Figs. 9A to 9C.

Specifically, as shown in (a) and (c), it is preferable that the bonding surface of the conductive material layer 127 and the n-type group III nitride semiconductor layer 113 is formed to be bent.

In particular, the bonding surface is preferably formed such that the conductive material layer 127 is in contact with at least four surfaces of the n-type group III nitride semiconductor layer 113.

Moreover, it is preferable to form so that an unevenness | corrugation is formed in a joining surface.

As a result, the junction area between the conductive material layer 127 and the n-type Group III nitride semiconductor layer 113 is widened, so that a current input through the n-side electrode 121 is transferred to the n-type Group III nitride semiconductor layer 113. The smooth flow can be prevented to increase the driving voltage Vf.

On the other hand, as shown in (b), it is preferable that the contact hole 123 is provided so that the cross-sectional area becomes wider from the p-type group III nitride semiconductor layer 115 toward the n-type group III nitride semiconductor layer 113.

As a result, the junction area between the conductive material layer 127 and the n-type group III nitride semiconductor layer 113 is increased, and the conductive material layer 127 can be prevented from being separated from the contact hole 123. .

In the above, specific embodiments of the present invention have been shown and described. However, the present invention can be embodied in various forms without departing from the spirit or essential characteristics thereof, and therefore, the above-described embodiments should not be limited by the contents of the detailed description, and further described above. Even if embodiments are not listed one by one in the description, they should be construed broadly within the spirit and scope defined in the appended claims. It is intended that the present invention cover the modifications and variations of this invention provided they come within the scope of the appended claims and their equivalents.

Claims (10)

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 interposed between the first group III nitride semiconductor layer and the second group III nitride semiconductor layer, wherein light is generated by recombination of electrons and holes;
A first contact hole penetrating through the first group III nitride semiconductor layer and the active layer and reaching the second group III nitride semiconductor layer;
A first electrode electrically connected to the first group III nitride semiconductor layer; And
A second electrode provided on the first group III nitride semiconductor layer and electrically connected to the second group III nitride semiconductor layer through the first contact hole and provided to be electrically insulated from the first group III nitride semiconductor layer; Group III nitride semiconductor light emitting device comprising. The method according to claim 1,
A second contact hole penetrating through the first group III nitride semiconductor layer and the active layer and reaching the second group III nitride semiconductor layer; And
A second sub-electrode provided on the first group III nitride semiconductor layer and electrically connected to the second group III nitride semiconductor layer through the second contact hole and electrically insulated from the first group III nitride semiconductor layer; And a second sub-electrode provided to be electrically connected to the second electrode. The method according to claim 2,
A branch electrode extending long from the second electrode, provided on the first group III nitride semiconductor layer, electrically connecting the second sub-electrode to the second electrode, and being electrically insulated from the first group III nitride semiconductor layer. Group III nitride semiconductor light-emitting device further comprises. The method according to claim 2,
A plurality of second sub-electrodes electrically connected to the second group III nitride semiconductor layer through the second contact hole and the second contact hole are provided.
The group III nitride semiconductor light emitting device of claim 2, wherein the plurality of second sub-electrodes are electrically connected to the second electrodes. The method of claim 4,
And at least one second sub-electrode is electrically connected to the second electrode via another second sub-electrode. The method of claim 4,
And at least two second sub-electrodes are electrically connected to the second electrode via one other second sub-electrode. The method according to claim 1,
A conductive material layer provided inside the first contact hole and contacting the second electrode and the second group III nitride semiconductor layer, respectively; And
An insulating material layer that insulates the conductive material layer from the first group III nitride semiconductor layer and the active layer, wherein the insulating material layer is interposed between the conductive material layer and the first group III nitride semiconductor layer and between the conductive material layer and the active layer inside the first contact hole. A group III nitride semiconductor light emitting device, further comprising an insulating material layer. The method of claim 7,
The group III nitride semiconductor light emitting device of claim 3, wherein the conductive material layer is in contact with at least four surfaces of the second group III nitride semiconductor layer. The method according to claim 8,
A group III nitride semiconductor light emitting device, characterized in that irregularities are provided on the surface of the second group III nitride semiconductor layer in contact with the conductive material layer. The method according to claim 1,
The first contact hole is a group III nitride semiconductor light emitting device, characterized in that the cross-sectional area is widened from the first group III nitride semiconductor layer toward the second group III nitride semiconductor layer.

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