WO2018208015A1

WO2018208015A1 - Light emitting diode including zinc oxide layer

Info

Publication number: WO2018208015A1
Application number: PCT/KR2018/004050
Authority: WO
Inventors: 이섬근; 이진웅; 양명학; 신찬섭
Original assignee: 서울바이오시스주식회사
Priority date: 2017-05-11
Filing date: 2018-04-06
Publication date: 2018-11-15
Also published as: KR20180124224A

Abstract

A light emitting diode according to embodiments of the present invention comprises: a plurality of light emitting cells which are arranged on a substrate and include active layers interposed between first conductivity type semiconductor layers and second conductivity type semiconductor layers, respectively; ZnO transparent electrodes arranged on the second conductivity type semiconductor layers of the light emitting cells, respectively; first contact electrodes in electrical contact with the first conductivity type semiconductor layers of the light emitting cells, respectively; second contact electrodes in electrical contact with the ZnO transparent electrodes, respectively; first pad electrodes electrically connected to some of the first contact electrodes; and second pad electrodes electrically connected to some of the second contact electrodes, wherein each of the light emitting cells has at least one through hole which extends through the second conductivity type semiconductor layer and the active layer to expose the first conductivity type semiconductor layer, and the active layers have the same light generating region.

Description

Light Emitting Diodes With Zinc Oxide Layer

The present invention relates to a light emitting diode having a zinc oxide (ZnO) layer.

Group III-nitride (III-N) based lasers or light emitting diodes have changed the field of lighting, display and data storage significantly and continue to expand their applications.

In III-N based LED devices, the typically low electrical conductivity of the p-type layer results in current concentration in the light emitting diode, causing low light efficiency. In order to achieve high light efficiency, a low ohmic contact is formed in the p-GaN layer which is highly transparent to the light generated by the light emitting diode, and a current dispersion layer having a low sheet resistance is introduced.

Indium-tin oxide (ITO), due to its relatively high electrical conductivity and low optical absorption, is currently the material of choice for LED current dispersion layers by various LED manufacturers. However, there are significant variations in the reported properties of ITO films depending on various factors such as deposition method, deposition surface properties, annealing conditions, element ratio of indium and tin in the film. In particular, since ITO contains a large amount of defects in the film, there is a limit to increasing the thickness, and therefore, there is a limit to improving current dispersion performance using high electrical conductivity.

To overcome this limitation of ITO, a technique has been employed which employs a relatively thin thickness ITO film and further introduces an extension electrode extending from the electrode pads. In this case, however, an increase in sheet resistance of ITO concentrates currents under the electrode pads and the extension electrode, and thus, an additional current block layer has been introduced under the ITO film near the electrode pads and the extension electrode. However, the introduction of the current block layer complicates the light emitting diode manufacturing process and also increases the forward voltage of the light emitting diode by reducing the contact area between the ITO film and the p-GaN layer. Further, when the n electrode pad is formed over the p-GaN layer, it is necessary to form an additional insulating layer or to remove the ITO film to expose the current block layer to insulate the n electrode pad and the ITO film. The formation of additional insulating layers further complicates the light emitting diode manufacturing process, and the ITO film removal further reduces the contact area between the ITO film and the p-GaN layer.

On the other hand, a single light emitting diode generally operates under a low voltage corresponding to the bandgap of the active layer. In order to solve such low voltage operating characteristics, a structure for connecting a plurality of light emitting cells in series has been developed. Furthermore, a plurality of light emitting cells may be connected in parallel to operate under a high current, and connecting the light emitting cells in parallel may help to distribute current.

However, a light emitting diode adopting a plurality of light emitting cells has a different light emitting area due to the limitation of the ITO film, and also has a shape in which the transparent electrodes formed on the light emitting cells or the shape of the extension electrodes are different from each other and thus enter the light emitting cells. A difference occurs in the current, and thus the current is concentrated in a specific light emitting cell.

An object of the present invention is to provide a light emitting diode capable of operating under high current and high voltage, and capable of uniformly distributing current in a plurality of light emitting cells.

A light emitting diode according to embodiments of the present invention includes a substrate; A plurality of light emitting cells disposed on the substrate, each of the light emitting cells including an active layer interposed between a first conductive semiconductor layer and a second conductive semiconductor layer; ZnO transparent electrodes disposed on second conductive semiconductor layers of the light emitting cells, respectively; First contact electrodes electrically contacting first conductive semiconductor layers of the light emitting cells; Second contact electrodes in electrical contact with the ZnO transparent electrodes, respectively; A first pad electrode electrically connected to some of the first contact electrodes; And a second pad electrode electrically connected to some of the second contact electrodes, wherein each of the light emitting cells exposes the first conductive semiconductor layer through the second conductive semiconductor layer and the active layer. It has at least one through hole, and the active layers have the same light generating region.

According to embodiments of the present invention, by adopting a ZnO transparent electrode and using second contact electrodes, current dispersing performance can be improved without a current block layer. Furthermore, a plurality of light emitting cells have the same light generating region. Since it is possible to distribute the current evenly to the plurality of light emitting cells.

Other advantages and effects of the present invention will become more apparent from the detailed description.

1 is a schematic plan view illustrating a light emitting diode according to an embodiment of the present invention.

2A and 2B are cross-sectional views taken along the cut lines A-A and B-B of FIG. 1, respectively.

3 is a schematic circuit diagram of the light emitting diode of FIG. 1.

4A, 4B, 4C, and 4D are schematic plan views illustrating a method of manufacturing a light emitting diode according to an embodiment of the present invention.

5 is a schematic plan view illustrating a light emitting diode according to still another embodiment of the present invention.

6A and 6B are cross-sectional views taken along the cut lines A-A and B-B of FIG. 5, respectively.

7 is a schematic plan view illustrating a light emitting diode according to still another embodiment of the present invention.

8 is a schematic plan view illustrating a light emitting diode according to still another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described embodiments of the present invention; The following embodiments are provided as examples to sufficiently convey the spirit of the present invention to those skilled in the art to which the present invention pertains. Accordingly, the present invention is not limited to the embodiments described below and may be embodied in other forms. In the drawings, widths, lengths, thicknesses, and the like of components may be exaggerated for convenience. In addition, when one component is described as "on" or "on" another component, each component is different from each other as well as when the component is "just above" or "on" the other component. It also includes a case where another component is interposed therebetween. Like numbers refer to like elements throughout.

A light emitting diode according to an embodiment of the present invention, a substrate; A plurality of light emitting cells disposed on the substrate, each of the light emitting cells including an active layer interposed between a first conductive semiconductor layer and a second conductive semiconductor layer; ZnO transparent electrodes disposed on second conductive semiconductor layers of the light emitting cells, respectively; First contact electrodes electrically contacting first conductive semiconductor layers of the light emitting cells; Second contact electrodes in electrical contact with the ZnO transparent electrodes, respectively; A first pad electrode electrically connected to some of the first contact electrodes; And a second pad electrode electrically connected to some of the second contact electrodes, wherein each of the light emitting cells exposes the first conductive semiconductor layer through the second conductive semiconductor layer and the active layer. It has at least one through hole, and the active layers have the same light generating region.

When the active layers have different areas, it is difficult to uniformly control the current input to the active layers. On the contrary, in the embodiments of the present invention, since the active layers have the same light generating region, currents flowing into the light emitting cells can be uniformly dispersed.

Furthermore, contact areas of the ZnO transparent electrodes and the second conductive semiconductor layers may be the same. Accordingly, the current can be more uniformly distributed in the plurality of light emitting cells.

In addition, each of the lower surfaces of the ZnO transparent electrodes may contact the upper surface of the second conductive semiconductor layer. Unlike the ITO film, no current block layer is used in embodiments of the present invention. Accordingly, the light emitting diode manufacturing process can be simplified.

In addition, the contact area between the first contact electrode and the first conductive semiconductor layer may be the same for each light emitting cell.

In addition, the first contact electrodes may have the same shape.

The light emitting diode may further include an insulating layer interposed between the first pad electrode and the ZnO transparent electrode. The first pad electrode may be disposed above the light emitting cell, and a ZnO transparent electrode may remain below the first pad electrode. Therefore, the light emitting area is formed under the first electrode pad like the other areas, thereby ensuring the light emitting area. Furthermore, all of the ZnO transparent electrodes on all the light emitting cells may have the same size, so that current may be uniformly distributed in the light emitting cells.

The first pad electrode may be disposed on the ZnO transparent electrode and directly connected to the first contact electrode contacting the first conductive semiconductor layer through the through hole.

In addition, the light emitting diode may further include an insulating layer interposed between the second pad electrode and the ZnO transparent electrode. In addition, a portion of the second pad electrode may contact the ZnO transparent electrode.

The second contact electrodes may be arranged in a mirror symmetric structure. In addition, the first contact electrodes may be arranged in a mirror symmetric structure.

The light emitting diode may include at least one first electrode connection part for electrically connecting neighboring first contact electrodes to connect the plurality of light emitting cells in parallel; At least one second electrode connector for electrically connecting neighboring second contact electrodes to connect the plurality of light emitting cells in parallel; And third electrode connection parts for electrically connecting a neighboring first contact electrode and a second contact electrode to connect the plurality of light emitting cells in series.

The plurality of light emitting cells may be electrically connected in a series-parallel structure through the first to third electrode connectors.

The first electrode connector may be connected to the first pad electrode, and the first electrode connector may be insulated from the ZnO transparent electrode by an insulating layer.

In addition, the second electrode connection part may be insulated from the first conductive semiconductor layer by an insulating layer.

In some embodiments, the plurality of light emitting cells are arranged in a matrix, the light emitting cells arranged in the same row share a first conductivity type semiconductor layer, and the light emitting cells arranged in the same column are separated from each other. A semiconductor layer, wherein the first electrode connector electrically connects the first contact electrodes on the light emitting cells arranged in the same row, and the second electrode connector is the second contact electrode on the light emitting cells arranged in the same row. And the third electrode connection part may electrically connect the first contact electrode and the second contact electrode on the light emitting cells arranged in the same column.

By arranging the light emitting cells as described above, it is possible to prevent the current from concentrating on the light emitting cells arranged in a specific column.

The first pad electrode and the second pad electrode may be disposed on the light emitting cells arranged in different rows.

Each of the ZnO transparent electrodes may have a roughened surface. The roughened surface improves the light extraction efficiency through the ZnO transparent electrode.

1 is a schematic plan view illustrating a light emitting diode according to an embodiment of the present invention, FIGS. 2A and 2B are cross-sectional views taken along the cutting lines AA and BB of FIG. 1, respectively, and FIG. 3 is the light emitting diode of FIG. 1. A schematic circuit diagram of the is shown.

First, referring to FIGS. 1, 2A, and 2B, the light emitting diode includes a substrate 21, a plurality of light emitting cells R1C1 to R3C3, ZnO transparent electrodes 29, and insulating

layers

31a, 31b, and 31aa. , 31bb, 31ab, first electrode pad 33a, first contact electrodes 33b, first electrode connectors 33ab, second electrode pad 35a, second contact electrodes 35b, and It may include the second electrode connectors 35ab and the third electrode connectors 335.

The substrate 21 is not particularly limited as long as it is a substrate capable of growing a gallium nitride semiconductor layer. Examples of the substrate 21 may include a sapphire substrate, a gallium nitride substrate, a SiC substrate, and the like, and may be a patterned sapphire substrate. The substrate 21 may have a rectangular or square outer shape as shown in the plan view of FIG. 1, but is not necessarily limited thereto. The size of the substrate 21 is not particularly limited and may be variously selected.

The plurality of light emitting cells R1C1 to R3C3 are disposed on the substrate 21. Each light emitting cell includes a first conductive semiconductor layer 23, a second conductive semiconductor layer 27, and an active layer 25 interposed therebetween. The first conductivity type semiconductor layer 23 is disposed on the substrate 21. The first conductivity type semiconductor layer 23 may be a layer grown on the substrate 21, and may be a gallium nitride based semiconductor layer doped with impurities such as Si.

The active layer 25 and the second conductive semiconductor layer 27 are disposed on the first conductive semiconductor layer 23. The active layer 25 and the second conductive semiconductor layer 27 may have an area smaller than that of the first conductive semiconductor layer 23. The active layer 25 and the second conductive semiconductor layer 27 may be located on the first conductive semiconductor layer 23 by mesa M formed by mesa etching.

The active layer 25 is formed of a gallium nitride-based semiconductor layer, and may have a single quantum well structure or a multiple quantum well structure. The composition and thickness of the well layer in the active layer 25 determines the wavelength of the light produced. In particular, it is possible to provide an active layer that generates ultraviolet light, blue light or green light by adjusting the composition of the well layer.

The second conductivity-type semiconductor layer 27 may be a gallium nitride-based semiconductor layer doped with p-type impurities, for example, Mg. Each of the first conductive semiconductor layer 23 and the second conductive semiconductor layer 27 may be a single layer, but is not limited thereto, and may be a multilayer or a superlattice layer. The first conductive semiconductor layer 23, the active layer 25, and the second conductive semiconductor layer 27 may be formed using a known method such as metal organic chemical vapor deposition (MOCVD) or molecular beam epitaxy (MBE). It may be formed and grown on the substrate 21 within.

The plurality of light emitting cells R1C1 to R3C3 may be arranged in a matrix structure by mesa etching regions and cell isolation regions ISO. Although the drawings show that the plurality of light emitting cells are arranged in a 3 × 3 matrix, the present invention is not limited thereto and may be arranged in various matrices of 2 × 2 or more.

Meanwhile, the light emitting cells arranged in the same row may share the first conductivity type semiconductor layer 23. For example, the light emitting cells R1C1, R1C2, and R1C3 arranged in the first row share the first conductive semiconductor layer, and the light emitting cells R2C1, R2C2, R2C3 arranged in the second row may also be formed in the second row. The first conductive semiconductor layer is shared, and the light emitting cells R3C1, R3C2, and R3C3 arranged in the third row also share the first conductive semiconductor layer. However, the light emitting cells arranged in the same row may have the active layer 25 and the second conductive semiconductor layer 27 separated from each other.

Meanwhile, the light emitting cells arranged in the same column may have the first conductivity type semiconductor layer 23 separated from each other. For example, the first conductive semiconductor layers 23 of the light emitting cells R1C1, R2C1, and R3C1 arranged in the first column are separated from each other by the cell isolation regions ISO, and the light emission arranged in the second column. The first conductive semiconductor layers 23 of the cells R1C2, R2C2, and R3C2 are also separated from each other by the cell isolation regions ISO, and the light emitting cells R1C3, R2C3, and R3C3 arranged in a third column. The first conductive semiconductor layers 23 are also separated by the cell isolation regions ISO.

In the present embodiment, the light emitting cells arranged in the same row share the first conductivity type semiconductor layer 23, thereby preventing the current from being concentrated along a specific column. That is, even if the current is concentrated through a specific light emitting cell in one row, the current may be redistributed through the first conductive semiconductor layer 23 shared with each other. It can be supplied uniformly distributed.

However, the present invention is not limited thereto, and light emitting cells in the same row may have first conductive semiconductor layers 23 separated from each other by a cell isolation region.

ZnO transparent electrodes 29 are disposed on the light emitting cells. The ZnO transparent electrode 29 has substantially the same shape as the second conductive semiconductor layer 27. However, the ZnO transparent electrode 29 may have a smaller area than the second conductivity type semiconductor layer 27. The lower surface of the ZnO transparent electrode 29 may be in contact with the upper surface of the second conductive semiconductor layer 27.

The ZnO transparent electrode 29 may comprise any material so long as Zn and O make up the majority of the compound and retain the ZulO crystal structure. ZnO transparent electrode 29 includes aluminum doped zinc oxide (AZO), gallium doped zinc oxide (GZO), and indium doped zinc oxide (IZO). ZnO transparent electrode 29 also includes materials having small amounts of other dopants and / or other impurities or inclusion materials, as well as nonstoichiometric materials due to the presence of vacancy and insertion-based material defects. .

The ZnO transparent electrode 29 deposits a thin continuous ZnO seed layer on the second conductive semiconductor layer 27, for example a p-type GaN layer, and then grows a ZnO bulk layer from the ZnO seed layer. Can be formed. The ZnO transparent electrode 29 may have a single crystal structure. The ZnO transparent electrode 29 may have a thickness of at least about five times the general thickness of the ITO film. For example, the ITO film is usually formed to have a thickness of about 500 GPa because of the absorptivity. However, since the ZnO transparent electrode 29 has a low absorption, it may be formed to have a thickness of 3000 Pa or more, and more than about 5000 Pa. The upper limit of the ZnO transparent electrode 29 is not particularly limited, but may be about 1 μm or less.

Each of the light emitting cells may include a through hole 30a penetrating through the second conductive semiconductor layer 27 and the active layer 27 to expose the first conductive semiconductor layer 23. The through hole 30a may also be formed in the ZnO transparent electrode 29. Therefore, the through hole 30a is surrounded by the ZnO transparent electrode 29, the second conductive semiconductor layer 27, and the active layer 25. The through hole 30a may have an elongated shape from one edge of the light emitting cell toward the other edge as shown. For example, as shown in FIG. 1, the through holes 30a may have an elongated shape in a direction perpendicular to the cell isolation region ISO.

The through holes 30a formed in the light emitting cells have the same size, and therefore, the exposed areas of the first conductive semiconductor layers 23 exposed by the through holes 30a have the same size. In addition, since the plurality of light emitting cells R1C1 to R3C3 have the same size and furthermore, the through holes 30a have the same size, the active layers 25 may have the same light generating area. have. That is, the active layers 25 may have the same outer shape, and through holes 30a having the same size penetrate through the active layers 25. Accordingly, regions in which the light may be generated in the active layers 25 are the same. Since the light generating regions of the active layers 25 are identical to each other, current may be uniformly distributed in the light emitting cells.

Meanwhile, as shown in FIG. 1, the through holes 30a may be formed at substantially the same positions in the active layers 25, but the light emitting cells R1C2 in which the second electrode pads 35a are formed. In this case, the position of the through hole 30a may be slightly modified by the second electrode pad 35a. That is, the through hole 30a formed in the light emitting cell R1C2 may be disposed slightly below the through holes 30a formed in the other light emitting cells in order to secure the separation distance from the second electrode pad 35a. have.

The first pad electrode 33a and the second pad electrode 35a are disposed to introduce electricity from the outside. As illustrated in FIG. 1, the first and

second pad electrodes

33a and 35a may be limitedly disposed in the upper region of the light emitting cell. For example, the first pad electrode 33a may be disposed on the light emitting cell R3C2, and the second pad electrode 35a may be disposed on the light emitting cell R1C2. However, when the light emitting cells are arranged in even rows, the first and second pad electrodes 33a 35a may be disposed over two light emitting cells.

On the other hand, the first pad electrode 33a is insulated from the ZnO transparent electrode 29 by the insulating layer 31a. The insulating layer 31a may be disposed under a portion of the first pad electrode 33a, and a portion of the first pad electrode 33a is exposed through the through hole 30a. ) May be electrically connected to constitute a part of the first contact electrode 33b.

The second pad electrode 35a may be partially spaced apart from the ZnO transparent electrode 29 by the insulating layer 31b. A portion of the second pad electrode 35a may contact the ZnO transparent electrode 29 and may form a portion of the second contact electrode 35b.

The first contact electrodes 33b are disposed in the through holes 30a and make ohmic contact with the first conductive semiconductor layers 23. Each first contact electrode 33b is spaced apart from the second conductivity type semiconductor layer 27 and the active layer 25. The first contact electrodes 33b may have the same size, and the areas where the first contact electrodes 33b and the first conductive semiconductor layer contact each other may also be the same.

The second contact electrodes 35b are positioned on the ZnO transparent electrodes 29 and are in electrical contact with the ZnO transparent electrodes 29, respectively. The second contact electrodes 35b may have substantially the same shape. Furthermore, the part where the 2nd electrode pad 35a contacts the ZnO transparent electrode 29 can also be made to be the same as some shape of a 2nd contact electrode.

The second contact electrodes 29 may be arranged in a mirror symmetric structure. These may be symmetrical with respect to the plane across the first pad electrode 33a and the second pad electrode 35a, for example. The first contact electrodes 29 may also be arranged in a mirror symmetric structure. By forming the first and

second contact electrodes

33b and 35b in a mirror symmetrical structure, a current can be uniformly supplied to both sides of the first and

second electrode pads

33a and 35a.

Meanwhile, the first electrode connector 33ab electrically connects adjacent first contact electrodes 33b to connect the plurality of light emitting cells in parallel. In particular, the first electrode connection part 33ab electrically connects the first contact electrodes 33b on the light emitting cells arranged in the same row. As illustrated in FIG. 1, the first electrode connection part 33ab may connect the first electrode pad 33a and the first electrode electrodes 33b. Meanwhile, an insulating layer 31aa is disposed between the first electrode connecting portion 33ab and the ZnO transparent electrode 29 to insulate the first electrode connecting portion 33ab from the ZnO transparent electrode 29. The insulating layer 31aa may be continuous from the insulating layer 31a.

The second electrode connector 35ab electrically connects adjacent second contact electrodes to connect the plurality of light emitting cells in parallel. In particular, the second electrode connection part 35ab electrically connects the second contact electrodes 35b on the light emitting cells arranged in the same row. Meanwhile, the insulating layer 31bb is disposed between the first conductivity type semiconductor layer 23 and the second electrode connection part 35ab in the mesa etching region to form the second electrode connection part 35ab in the first conductivity type semiconductor layer 23. Insulate from

The third electrode connector 335 electrically connects the neighboring first and second contact electrodes to connect the plurality of light emitting cells in series. The third electrode connector 335 electrically connects the first contact electrode 33b and the second contact electrode 35b on the light emitting cells arranged in the same column. Meanwhile, the insulating layer 31ab is interposed between the third electrode connector 335 and the ZnO transparent electrode 29 to prevent the third electrode connector 335 from being short-circuited to the ZnO transparent electrode 29. The insulating layer 31ab may also be disposed in the cell isolation region (ISO) region, and the third electrode connection portion 335 may include the first conductive semiconductor layer 23, the active layer 25, or the second conductive semiconductor layer 27. To prevent a short circuit.

As shown in FIG. 3, through the first electrode connection part 33ab, the second electrode connection part 35ab, and the third electrode connection part 335. The light emitting cells are connected in a series-parallel structure. In FIG. 3, the dotted line shows the electrical connection by the first conductivity type semiconductor layer 23 shared with each other.

According to the present embodiment, the ZnO transparent electrode 29 is adopted, and the light generating regions of the active layers 25 are the same, and the first contact electrodes 33b and the second contact electrodes 35b are made. By forming the same substantially, it is possible to uniformly distribute the current in the plurality of light emitting cells.

4A through 4D are schematic plan views illustrating a method of manufacturing a light emitting diode according to an exemplary embodiment of the present invention.

2A, 2B, and 4A, first, the first conductive semiconductor layer 23, the active layer 25, and the second conductive semiconductor layer 27 are grown on the substrate 21. As shown in FIG. These semiconductor layers can be formed using techniques such as metal organic chemical vapor growth, molecular beam epitaxy, hydride vapor phase growth, and the like. Subsequently, a ZnO transparent electrode 29 is formed on the second conductivity type semiconductor layer 27. The ZnO transparent electrode 29 may be formed by various methods, but in particular, the single crystal ZnO transparent electrode 29 having a wurtzite structure may be formed by growing a ZnO bulk layer using an aqueous solution method in which a ZnO seed layer is formed. have.

Thereafter, through-holes 30a and mesas M are formed using a photo and etching process. The ZnO transparent electrode 29, the second conductive semiconductor layer 27, and the active layer 25 may be patterned using the same photoresist pattern. In this case, the ZnO transparent electrode 29 may be etched by using wet etching, for example, and the second conductive semiconductor layer 27 and the active layer 25 may be etched by using dry etching. Accordingly, a plurality of light emitting cell regions arranged in a matrix structure may be defined.

Furthermore, the through holes 30a formed in the light emitting cell regions all have the same size, and thus, the active layer 25 in each light emitting cell region has a constant light generating region.

2A, 2B, and 4B, cell isolation regions ISO are formed. The cell isolation regions ISO may be formed using a photolithography and etching process, and the upper surface of the substrate 21 may be exposed in the cell isolation regions ISO. Rows of light emitting cells are separated from each other by the cell isolation regions ISO.

2A, 2B, and 4C, insulating

layers

31a, 31b, 31aa, 31bb, and 31ab are formed. The insulating layer may be formed of, for example, a single layer of SiO 2 or Si 3 N 4, but is not limited thereto. For example, the insulating layer may have a multi-layer structure including a silicon nitride film and a silicon oxide film, and a distribution bragg is formed by alternately stacking layers having different refractive indices in an SiO 2 film, a TiO 2 film, a ZrO 2 film, an MgF 2 film, or an Nb 2 O 5 film. It may also include a reflector DBR. In particular, the adoption of DBR prevents light generated in the active layer 25 from being absorbed and lost by various electrodes and connections disposed on the insulating

layers

31a, 31b, 31aa, 31bb, 31ab.

2A, 2B, and 4D, the first pad electrode 33a, the first contact electrodes 33b, the second pad electrode 35a, the second contact electrodes 35ab, and the first electrode connection part ( 33ab, second electrode connectors 35ab, and third electrode connectors 335 are formed. These can be formed together in the same process with the same material.

Subsequently, the light emitting diode of FIG. 1 is completed by dividing the substrate 21 into individual light emitting diodes through a scribing process.

According to embodiments of the present invention, the ZnO transparent electrode 29 is directly formed on the second conductive semiconductor layer 27 without introducing a current block layer. As a result, the light emitting diode manufacturing process is extremely simple.

5 is a schematic plan view illustrating a light emitting diode according to still another embodiment of the present invention, and FIGS. 6A and 6B are cross-sectional views taken along the cutting lines A-A and B-B of FIG. 5.

5, 6A and 6B, the light emitting diode according to the present embodiment has a surface R roughened by ZnO transparent electrodes 29, which is generally similar to the light emitting diode described with reference to FIGS. There is a difference in having.

The ZnO transparent electrodes 29 have a flat surface and a roughened surface R. The roughened surface R improves the light extraction efficiency. For example, the first electrode pad 33a, the second electrode pad 35a, the second contact electrodes 35b and the electrode connecting portions 33ab, 35ab, and 335 and the insulating

layers

31a, 31b, 31aa, and 31bb. , 31ab) and the like have a flat surface, and a roughened surface R is formed in the surrounding areas. In addition, a flat surface may be formed in the edge regions of the ZnO transparent electrode 29.

The roughened surface R forms a photoresist pattern exposing a region where the roughened surface R is to be formed before forming the insulating

layers

31a, 31b, 31aa, 31bb, and 31ab, and using ZnO using an acid solution. It can be formed by wet treating the surface. The maximum depth of the roughened surface R produced by the wet treatment may be in the range of approximately 200 mm to 2000 mm.

Referring to FIG. 7, the light emitting diode according to the present embodiment is generally similar to the light emitting diode described with reference to FIGS. 1 to 3, but there is a difference in that a plurality of through holes 130a are formed in some light emitting cells. . In order to spread the contact position of the first contact electrode 33b widely, a plurality of through holes 130a may be formed in one light emitting cell. However, when it is difficult to widely disperse the first contact electrode 33b in the light emitting cells in which the first electrode pad 33a or the second electrode pad 35a is formed, each of the light emitting cells has one through hole ( 30a) may be formed. However, the sum of the sizes of the plurality of through holes 130a formed in each of the light emitting cells may be the same as that of the through holes 30a. Thus, the first contact electrode 33b may be formed of the first conductive semiconductor layer. The contact area in contact with 23 may be the same in all light emitting cells.

Also in this embodiment, as described above with reference to FIGS. 5, 6A, and 6B, a roughened surface R may be further formed on the ZnO surface.

Referring to FIG. 8, the light emitting diode according to the present embodiment is generally similar to the light emitting diode described with reference to FIGS. 1 to 3, but in the previous embodiment, the second electrode connecting portions 35ab are formed in the first row R1. Unlike to be positioned on the light emitting cells disposed in the ()), in the present embodiment, the second electrode connecting portions (35ab) is different from that disposed on the light emitting cells of all the rows.

According to the present embodiment, the second electrode connecting portions 35ab are disposed not only in the first row R1 but also in the other rows R2 and R3, so that even if current is concentrated through a specific light emitting cell in the first row R1, In addition to the current dispersion by the first conductivity type semiconductor layer 23, the current can be distributed using the second electrode connecting portions 35ab to more evenly distribute the current to the light emitting cells in the next rows R2 and R3. You can.

In addition, in the present embodiment, as described above with reference to FIGS. 5, 6A, and 6B, the roughened surface R may be further formed on the ZnO surface, and as described with reference to FIG. Likewise, a plurality of through holes 130a may be formed in one light emitting cell.

In the above, various embodiments of the present invention have been described, but the present invention is not limited to these embodiments. In addition, the matters or components described with respect to one embodiment may be applied to other embodiments without departing from the technical spirit of the present invention.

Claims

Board;

A plurality of light emitting cells disposed on the substrate, each of the light emitting cells including an active layer interposed between a first conductive semiconductor layer and a second conductive semiconductor layer;

ZnO transparent electrodes disposed on second conductive semiconductor layers of the light emitting cells, respectively;

First contact electrodes electrically contacting first conductive semiconductor layers of the light emitting cells;

Second contact electrodes in electrical contact with the ZnO transparent electrodes, respectively;

A first pad electrode electrically connected to some of the first contact electrodes; And

A second pad electrode electrically connected to some of the second contact electrodes,

Each of the light emitting cells has at least one through hole through the second conductive semiconductor layer and the active layer to expose the first conductive semiconductor layer,

The active layers have the same light generating region with each other.
The method according to claim 1,

And a contact area between the ZnO transparent electrodes and the second conductive semiconductor layer is the same.
The method according to claim 2,

Each of the ZnO transparent electrodes has a bottom surface thereof in contact with an upper surface of the second conductive semiconductor layer.
The method according to claim 1,

The light emitting diode of claim 1, wherein the contact area between the first contact electrode and the first conductive semiconductor layer is the same for each light emitting cell.
The light emitting diode of claim 4, wherein the first contact electrodes have the same shape.
The method according to claim 1,

The light emitting diode further comprising an insulating layer interposed between the first pad electrode and the ZnO transparent electrode.
The method according to claim 6,

The first pad electrode is disposed on the ZnO transparent electrode, the light emitting diode directly connected to the first contact electrode in contact with the first conductive semiconductor layer through the through hole.
The method according to claim 1,

Further comprising an insulating layer interposed between the second pad electrode and the ZnO transparent electrode,

A portion of the second pad electrode is in contact with the ZnO transparent electrode.
The method according to claim 1,

And the second contact electrodes are arranged in a mirror symmetric structure.
The method according to claim 9,

And the first contact electrodes are arranged in a mirror symmetric structure.
The method according to claim 1,

At least one first electrode connection part for electrically connecting neighboring first contact electrodes to connect the plurality of light emitting cells in parallel;

At least one second electrode connector for electrically connecting neighboring second contact electrodes to connect the plurality of light emitting cells in parallel; And

And a third electrode connection part for electrically connecting a neighboring first contact electrode and a second contact electrode to connect the plurality of light emitting cells in series.
The method according to claim 11,

The first electrode connection part is connected to the first pad electrode,

The first electrode connector is insulated from the ZnO transparent electrode by an insulating layer.
The method according to claim 11,

The second electrode connection part is insulated from the first conductive semiconductor layer by an insulating layer.
The method according to claim 11,

The plurality of light emitting cells are arranged in a matrix,

The light emitting cells arranged in the same row share the first conductivity type semiconductor layer,

The light emitting cells arranged in the same column have a first conductivity type semiconductor layer separated from each other,

The first electrode connector electrically connects the first contact electrodes on the light emitting cells arranged in the same row.

The second electrode connector electrically connects the second contact electrodes on the light emitting cells arranged in the same row.

The third electrode connector is a light emitting diode for electrically connecting the first contact electrode and the second contact electrode on the light emitting cells arranged in the same column.
The method according to claim 14,

The first pad electrode and the second pad electrode are disposed on top of the light emitting cells arranged in different rows.
The method according to claim 1,

Each of the ZnO transparent electrodes has a roughened surface.