CN107256877B - led - Google Patents

Abstract

A light emitting diode is disclosed herein. The light emitting diode includes a plurality of light emitting units and interconnects connecting the light emitting units to each other, wherein at least one of the interconnects includes a common cathode electrically connected to the two light emitting units in common; each light emitting unit includes a first A conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer; the two light-emitting units share the first conductive type semiconductor layer; a transparent electrode layer is continuously disposed between the two light emitting units, and a common cathode is electrically connected to the two light emitting units through a transparent electrode layer.

Description

led

technical field

The present invention relates to a light emitting diode, and more particularly, to a light emitting diode including a plurality of light emitting cells connected to each other by interconnects on a single substrate.

Background technique

Gallium Nitride (GaN)-based Light Emitting Diodes (LEDs) have been used in a wide range of applications including full-color LED displays, LED traffic light panels, white LEDs, and the like. In recent years, white light-emitting diodes with higher luminous efficiency than existing fluorescent lamps are expected to surpass existing fluorescent lamps in the field of general lighting.

Light emitting diodes can be driven to emit light at a low forward voltage of about 2V to about 4V and need to supply a direct current. Therefore, when the light emitting diode is directly connected to an alternating current (AC) power source, the light emitting diode repeats on/off operations according to the direction of the current, so it cannot continuously emit light and may be easily damaged by reverse current.

To address such problems with light emitting diodes, WO 2004/023568(A1) by Sakai et al. (titled "LIGHT-EMITTING DEVICE HAVING LIGHT-EMITTINGELEMENTS") discloses a device that can be used by connecting directly to a high voltage AC power supply led.

The AC light emitting diode of WO 2004/023568 (A1 ) comprises a plurality of light emitting elements connected to each other by air bridge interconnects to be driven by an AC power source. Such air bridge interconnects can be easily damaged by external forces and can be deformed by external forces to cause short circuits.

In order to solve such a disadvantage of the air bridge interconnect, for example, AC light emitting diodes are disclosed in Korean Patent Nos. 10-069023 and 10-1186684.

1 is a schematic plan view of a typical light emitting diode including a plurality of light emitting units, and FIGS. 2 and 3 are cross-sectional views taken along line A-A of FIG. 1 .

1 and 2 , the light emitting diode includes a substrate 21 , a plurality of light emitting cells 26 including S1 and S2 , a transparent electrode layer 31 , an insulating layer 33 and interconnects 35 . In addition, each of the light emitting units 26 includes a lower semiconductor layer 25 , an active layer 27 and an upper semiconductor layer 29 , and a buffer layer 23 may be disposed between the substrate 21 and the light emitting unit 26 .

The light emitting unit 26 is formed by patterning the lower semiconductor layer 25, the active layer 27, and the upper semiconductor layer 29 grown on the substrate 21, and the transparent electrode layer 31 is formed on each of the light emitting units S1, S2. In each light emitting cell 26 , the upper surface of the lower semiconductor layer 25 is partially exposed by partially removing the active layer 27 and the upper semiconductor layer 29 to be connected to the interconnection 35 .

Next, the insulating layer 33 is formed to cover the light emitting unit 26 . The insulating layer 33 includes a side insulating layer 33 a covering the side surface of the light emitting unit 26 and an insulating protective layer 33 b covering the transparent electrode layer 31 . The insulating layer 33 is formed with an opening through which a portion of the transparent electrode layer 31 is exposed and an opening through which the lower semiconductor layer 25 is exposed. Then, the interconnection member 35 is formed on the insulating layer 33, wherein the first interconnection portion 35p of the interconnection member 35 is connected to the transparent electrode layer 31 of one light emitting cell S1 through the opening of the insulating layer 33, The two interconnection portions 35n are connected to the lower semiconductor layer 25 of the other light emitting cell S2 adjacent to the one light emitting cell S1 through another opening of the insulating layer 33 . The second interconnection portion 35 n is connected to the upper surface of the lower semiconductor layer 25 exposed by partially removing the active layer 27 and the upper semiconductor layer 29 .

In the conventional technology, the interconnection 35 is formed on the insulating layer 33, and thus deformation due to external force can be prevented. In addition, since the interconnection 35 is separated from the light emitting unit 26 by the side insulating layer 33a, the light emitting unit 26 can be prevented from being short-circuited due to the interconnection 35.

However, such conventional light emitting diodes may have limitations in terms of current spreading in the area of the light emitting unit 26 . Specifically, the current may be concentrated under the end of the interconnect 35 connected to the transparent electrode layer 31 , and not spread uniformly in the area of the light emitting unit 26 . Current crowding may become severe as the current density increases.

In addition, the transparent electrode layer 31 is restrictively placed in the region of the upper semiconductor layer 29 . As a result, the transparent electrode layer 31 has a relatively narrow area and increases the resistance of the light emitting diode, thereby causing the forward voltage (Vf) of the light emitting diode to increase. As the number of light emitting cells 26 increases, the resistance of the transparent electrode layer 31 becomes considerably large.

On the other hand, in order to prevent current crowding, the current blocking layer 30 may be provided between the transparent electrode layer 31 and the light emitting unit 26 to prevent current crowding under the first interconnection portion 35p of the interconnection member 35 .

FIG. 3 is a cross-sectional view of a light emitting diode including a current blocking layer 30 in the prior art.

Referring to FIGS. 1 and 3 , the current blocking layer 30 is placed under the first interconnection portion 35p of the interconnection member 35 . The current blocking layer 30 blocks current from flowing from the first interconnection portion 35p to the upper semiconductor layer 29 located directly under the first interconnection portion 35p. Therefore, the current blocking layer 30 can prevent current crowding under the first interconnection portion 35p of the interconnection 35. FIG. In addition, the current blocking layer 30 may be formed as a reflector such as a distributed Bragg reflector to prevent light generated in the active layer 27 from being absorbed into the first interconnection portion 35p of the interconnection 35 .

However, when the light emitting diode further includes the current blocking layer 30 , as shown in FIG. 3 , an additional process of forming the current blocking layer 30 by photolithography and etching is required, making it difficult to ensure process stability while improving manufacturing cost. Specifically, when the current blocking layer 30 is exposed outside the transparent electrode layer 31, the current blocking layer 30 may be damaged due to BOE or the like in a subsequent process. Therefore, in the related art, in order to prevent damage to the current blocking layer 30 in subsequent processes, the current blocking layer 30 is covered by the transparent electrode layer 31 as shown in FIG. 3 .

Furthermore, since the transparent electrode layer 31 is restrictively placed in the area of the upper semiconductor layer 29 , it is difficult to achieve uniform current spreading over the entire upper semiconductor layer 29 , and the light emitting diode still has resistance due to the small area of the transparent electrode layer 31 too big a problem.

SUMMARY OF THE INVENTION

An object of the present invention is to provide a light emitting diode.

Another object of the present invention is to provide a light emitting diode capable of solving at least one of the above technical problems.

The present invention provides a light emitting diode comprising: a plurality of light emitting units; and interconnects to connect the light emitting units to each other, wherein at least one of the interconnects may include a common electrical connection to the two light emitting units the common cathode; each light-emitting unit may include a first conductive type semiconductor layer, a second conductive type semiconductor layer, and an active layer disposed between the first conductive type semiconductor layer and the second conductive type semiconductor layer; the two light-emitting The cells may share the first conductive type semiconductor layer; wherein a transparent electrode layer may be continuously disposed between the two light-emitting cells, and a common cathode may be electrically connected to the two light-emitting cells through the transparent electrode layer.

The present invention also provides a light emitting diode, the light emitting diode comprises: a first light emitting unit and a second light emitting unit, which are separated from each other on a substrate; a first transparent electrode layer, which is electrically connected to the first light emitting unit; an interconnection member, electrically connecting the first light emitting unit to the second light emitting unit; and a first insulating layer, wherein a first transparent electrode layer may be disposed on the upper surface of the first light emitting unit to be connected to the first light emitting unit while at least partially covering The side surface of the first light emitting unit, and the first insulating layer may separate the first transparent electrode layer from the side surface of the first light emitting unit.

Description of drawings

The accompanying drawings, which are included to provide a further understanding of the invention, are incorporated in and constitute a part of this specification, illustrate embodiments of the invention, and together with the description serve to explain the principles of the invention.

FIG. 1 is a schematic plan view of a light emitting diode in the related art.

FIG. 2 is a cross-sectional view taken along line A-A of FIG. 1 .

FIG. 3 is a cross-sectional view of a light emitting diode including a current blocking layer 30 in the prior art.

4 is a schematic plan view of a light emitting diode according to an exemplary embodiment of the present invention, and FIG. 5 is a schematic cross-sectional view taken along line B-B of FIG. 4 .

6 to 10 are schematic cross-sectional views illustrating a method of manufacturing the light emitting diode according to the exemplary embodiment of FIG. 4 .

11 is a schematic plan view of a light emitting diode according to another exemplary embodiment of the present invention, and FIG. 12 is a cross-sectional view taken along line B-B of FIG. 11 .

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

(a) and (b) in FIG. 14 are cross-sectional views taken along line A-A and line B-B of FIG. 13 , respectively.

FIG. 15 is a schematic circuit diagram of the light emitting diode of FIG. 13 .

FIG. 16 is a schematic circuit diagram illustrating a light emitting diode according to yet another embodiment of the present invention.

Detailed ways

The present invention is described more fully hereinafter with reference to the accompanying drawings, in which embodiments of the invention are shown. However, the present invention may be embodied in many different forms and should not be construed as limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough, and will fully convey the scope of the invention to those skilled in the art. In the drawings, the size and relative sizes of layers and regions may be exaggerated for clarity. The same reference numbers refer to the same elements in the figures.

It will be understood that when an element or layer is referred to as being "on" or "connected to" another element or layer, the element or layer can be directly on the other element or layer or directly connected to the other element or layer, or intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on" or "directly connected to" another element or layer, there are no intervening elements or layers present. It will be understood that, for the purposes of this disclosure, "at least one (species) of X, Y, and Z" can be construed to mean only X, only Y, only Z, or two or more of X, Y, and Z Any combination of terms (eg, XYZ, XYY, YZ, ZZ).

For ease of description, spatially relative terms such as "below", "below", "below", "above", and "above" may be used herein to describe the figures as shown in the figures. The relationship of one element or feature to another element or feature is shown in . It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation other than the orientation depicted in the figures. For example, if the device in the figures is turned over, elements described as "below" or "beneath" other elements or features would then be oriented "above" the other elements or features. Thus, the exemplary term "below" can include both an orientation of "above" and "below". The device may be otherwise oriented (rotated 90 degrees or at other orientations) and the spatially relative descriptors used herein interpreted accordingly.

4 is a schematic plan view of a light emitting diode according to an exemplary embodiment of the present invention, and FIG. 5 is a schematic cross-sectional view taken along line B-B of FIG. 4 .

4 and 5 , the light emitting diode includes a substrate 151 , a light emitting cell S1 , a light emitting cell S2 , a first insulating layer 160 a , a second insulating layer 160 b , a transparent electrode layer 161 , and interconnects 165 . The light emitting diode may further include a buffer layer 153 .

The substrate 151 may be an insulating substrate or a conductive substrate. For example, the substrate 151 may be a sapphire substrate, a gallium nitride substrate, a silicon carbide (SiC) substrate, or a silicon substrate. In addition, the substrate 151 may be a substrate having a concavo-convex pattern (not shown) on its upper surface, for example, a patterned sapphire substrate.

On the single substrate 151, the first light emitting unit S1 and the second light emitting unit S2 are separated from each other. The first light emitting unit S1 and the second light emitting unit S2 may be formed of a gallium nitride semiconductor. Each of the first light emitting unit S1 and the second light emitting unit S2 has a stack structure 156 including a lower semiconductor layer 155, an upper semiconductor layer 159 disposed on one region of the lower semiconductor layer 155, and an upper semiconductor layer 159 disposed on the lower semiconductor layer 155 and The active layer 157 between the upper semiconductor layers 159 . Here, the lower semiconductor layer 155 and the upper semiconductor layer 159 may be a p-type semiconductor layer and an n-type semiconductor layer, respectively, or vice versa.

Each of the lower semiconductor layer 155, the active layer 157, and the upper semiconductor layer 159 may be formed of a gallium nitride-based material (eg, (Al,In,Ga)N). The active layer 157 may be formed of a material having a composition capable of emitting light in a desired wavelength range (eg, UV light or blue light), and the lower semiconductor layer 155 and the upper semiconductor layer 159 may be formed of a material having a wider band gap than that of the active layer 157 . The material of the gap is formed.

As shown, the lower semiconductor layer 155 and/or the upper semiconductor layer 159 may be formed of a single layer or multiple layers. In addition, the active layer 157 may have a single quantum well structure or a multiple quantum well structure.

Each of the first light emitting unit S1 and the second light emitting unit S2 may have an inclined side surface whose inclination angle with respect to the upper surface of the substrate 151 ranges from 15° to 80°.

As shown in FIG. 5, the active layer 157 and the upper semiconductor layer 159 may be placed on some regions of the lower semiconductor layer 155, and other regions of the lower semiconductor layer 155 may be exposed. Alternatively, the upper surface of the lower semiconductor layer 155 may be completely covered by the active layer 157 so that side surfaces of the lower semiconductor layer 155 are exposed.

In FIG. 5 , the first light emitting unit S1 and the second light emitting unit S2 are partially shown. However, it should be noted that the first light emitting unit S1 and the second light emitting unit S2 may have similar or identical structures, as shown in FIG. 4 . Specifically, the first light emitting unit S1 and the second light emitting unit S2 may have the same gallium nitride-based semiconductor stack structure, and may have inclined side surfaces of the same structure.

The buffer layer 153 may be disposed between the light emitting cells S1 , S2 and the substrate 151 . When the substrate 151 is a growth substrate, the buffer layer 153 is used to relieve lattice mismatch between the substrate 151 and the lower semiconductor layer 155 formed thereon.

The transparent electrode layer 161 is provided on each of the light emitting cells S1, S2. Specifically, the first transparent electrode layer 161 is disposed on the first light emitting unit S1, and the second transparent electrode layer 161 is disposed on the second light emitting unit S2. The transparent electrode layer 161 may be disposed on the upper surface of the upper semiconductor layer 159 to be connected to the upper semiconductor layer 159 .

The first transparent electrode layer 161 and/or the second transparent electrode layer 161 may cover a part of the side surface of the first light emitting unit S1 and/or the second light emitting unit S2, and may cover the first light emitting unit S1 and/or the second light emitting unit S1 At least three surfaces of cell S2. In the embodiment shown in FIG. 4 , each of the first transparent electrode layer 161 and the second transparent electrode layer 161 covers four side surfaces of the first light emitting unit S1 or the second light emitting unit S2.

Therefore, the transparent electrode layer 161 may have a wider area than the upper area of the corresponding light emitting cell S1 or S2. In addition, the transparent electrode layer 161 may cover the entire upper surface of the upper semiconductor layer 159 . The transparent electrode layer 161 has a wider area (or area) than the area (or area) of the corresponding light emitting unit S1 or S2, so that the resistance of the transparent electrode layer 161 can be reduced. The transparent electrode layer 161 placed on the second light emitting unit S2 adjoins the upper semiconductor layer 159 of the second light emitting unit S2 and is insulated from the lower semiconductor layer 155 of the second light emitting unit S2 by the first insulating layer 160a. That is, the transparent electrode layer 161 may adjoin the exposed area of the upper semiconductor layer 159 and may be placed on the first insulating layer 160 a covering the exposed area of the lower semiconductor layer 155 .

The first insulating layer 160 a separates the transparent electrode layer 161 from the side surface of the corresponding light emitting cell S1 or S2 to prevent the light emitting cell S1 or S2 from being electrically connected to the transparent electrode layer 161 . The first insulating layer 160a may cover the side surface of the corresponding light emitting unit S1 or S2 along the edge of the corresponding light emitting unit. In addition, the first insulating layer 160a may cover the upper surface of the substrate 151 around the light emitting cells S1, S2. On the other hand, the first insulating layer 160a has an opening 160hn exposing the lower semiconductor layer 155 and an opening 160hp exposing the upper semiconductor layer 159 . The transparent electrode layer 161 is connected to the upper semiconductor layer 159 through the opening 160hp formed on the upper surface of each of the light emitting cells S1, S2. Since the first insulating layer 160 a is formed along the edge of the upper surface of the upper semiconductor layer 159 , the transparent electrode layer 161 may be recessed from the edge of the upper semiconductor layer 159 to be connected to the upper semiconductor layer 159 . Therefore, the light emitting diode according to the present embodiment can prevent current crowding at the edge of the upper semiconductor layer 159 through the sidewalls of the light emitting cells S1, S2.

The second insulating layer 160b may be formed on each of the light emitting cells S1, S2 so as to be interposed between the transparent electrode layer 161 and the light emitting cells S1, S2. A portion of the transparent electrode layer 161 is placed on the second insulating layer 160b. The second insulating layer 160b may be disposed close to the edge of each of the light emitting cells S1, S2, without being limited thereto. Alternatively, the second insulating layer 160b may be disposed at the central region of each of the light emitting cells S1, S2. The second insulating layer 160b may be formed of the same material as that of the first insulating layer 160a (eg, silicon oxide or silicon nitride).

The interconnect 165 electrically connects the first light emitting cell S1 to the second light emitting cell S2. The interconnect 165 includes a first connection portion (one end) 165p and a second connection portion (the other end) 165n. The first connection part 165p is electrically connected to the transparent electrode layer 161 on the first light emitting unit S1, and the second connection part 165n is electrically connected to the lower semiconductor layer 155 of the second light emitting unit S2. Specifically, the second connection part 165n may be connected to the lower semiconductor layer 155 through the opening 160hn of the first insulating layer 160a. The first light emitting cell S1 is connected in series to the second light emitting cell S2 through the first connection portion 165p and the second connection portion 165n of the interconnection member 165 .

On the other hand, the first connection part 165p may be disposed close to one edge of the first light emitting unit S1, without being limited thereto. Alternatively, the first connection part 165p may be disposed at the central area of the first light emitting unit S1.

The interconnection 165 may be in contact with the transparent electrode layer 161 over the entire overlapping area between the interconnection 165 and the transparent electrode layer 161 . In the related art, a part of the insulating layer 33 is provided between the transparent electrode layer 31 and the interconnection member 35 . However, in this embodiment, the interconnection 165 is in direct contact with the transparent electrode layer 161 without interposing any insulating material therebetween.

In addition, the second insulating layer 160b may be disposed on the entire overlapping area between the interconnect 165 and the transparent electrode layer 161 on the first light emitting cell S1.

In this embodiment, the second connection portion 165n is connected to the exposed upper side of the lower semiconductor layer 155 . Alternatively, the second connection part 165n may be connected to the inclined side surface of the second light emitting cell S2, in particular, to the inclined side surface of the lower semiconductor layer 155 of the second light emitting cell S2. In this case, it is not necessary to expose the upper surface of the lower semiconductor layer 155 , and the first insulating layer 160 a is formed to expose the inclined side surface of the lower semiconductor layer 155 .

In this embodiment, the light emitting diode is shown to include two light emitting cells, namely, a first light emitting cell S1 and a second light emitting cell S2. However, the present invention is not limited thereto, and more light emitting cells may be electrically connected to each other through the interconnection 165 . For example, the interconnects 165 may electrically connect the lower semiconductor layers 155 of adjacent light emitting cells to their transparent electrode layers 161 to form a series array of light emitting cells. Although the light emitting diodes may have a single series array formed on a single substrate 151, the present invention is not limited thereto. Alternatively, the light emitting diodes may comprise multiple series arrays connected in parallel or anti-parallel to each other. Additionally, the light emitting diodes may be provided with bridge rectifiers (not shown) connected to the series array of light emitting units, so that the light emitting units may be driven by AC power. The bridge rectifier may be formed by connecting light emitting cells having the same structure as that of the light emitting cells S1 , S2 using the interconnect 165 .

6 to 10 are cross-sectional views illustrating a method of manufacturing the light emitting diode according to the exemplary embodiment of FIG. 4 .

6 , a semiconductor stack structure 156 is formed on the substrate 151 , and the semiconductor stack structure 156 includes a lower semiconductor layer 155 , an active layer 157 and an upper semiconductor layer 159 . In addition, before forming the lower semiconductor layer 155, a buffer layer 153 may be formed on the substrate 151.

The substrate 151 may be a sapphire (Al ₂ O ₃ ) substrate, a silicon carbide (SiC) substrate, a zinc oxide (ZnO) substrate, a silicon (Si) substrate, a gallium arsenide (GaAs) substrate, a gallium phosphide (GaP) substrate, an oxide A lithium aluminum (LiAl ₂ O ₃ ) substrate, a boron nitride (BN) substrate, an aluminum nitride (AlN) substrate, or a gallium nitride (GaN) substrate, but not limited thereto. That is, the substrate 151 may be formed of a material selected from various materials according to the material of the semiconductor layer to be formed on the substrate 151 . In addition, the substrate 151 may be a substrate having a concavo-convex pattern on its upper surface, for example, a patterned sapphire substrate.

The buffer layer 153 is formed to relieve lattice mismatch between the substrate 151 and the lower semiconductor layer 155 formed thereon, and may be formed of, for example, gallium nitride (GaN) or aluminum nitride (AlN). When the substrate 151 is a conductive substrate, the buffer layer 153 may be formed as an insulating layer or a semi-insulating layer, eg, AlN or semi-insulating GaN.

Each of the lower semiconductor layer 155, the active layer 157, and the upper semiconductor layer 159 may be formed of a gallium nitride-based semiconductor material such as (Al,In,Ga)N. The lower semiconductor layer 155, the upper semiconductor layer 159 and the active layer 157 may be intermittently or continuously formed by metal organic chemical vapor deposition (MOCVD), molecular beam epitaxy, hydride vapor phase epitaxy (HVPE), or the like.

Here, the lower semiconductor layer 155 and the upper semiconductor layer 159 may be an n-type semiconductor layer and a p-type semiconductor layer, respectively, or vice versa. The n-type semiconductor layer may be formed by doping the gallium nitride-based compound semiconductor layer with, for example, silicon (Si) impurities, and the p-type semiconductor layer may be formed by doping the gallium nitride-based compound semiconductor layer with, for example, magnesium (Mg) impurities mixed to form.

Referring to FIG. 7, a plurality of light emitting cells S1, S2 are formed to be separated from each other by photolithography and etching. Each of the light emitting cells S1, S2 may be formed to have inclined side surfaces, and the upper surface of the lower semiconductor layer 155 of each of the light emitting cells S1, S2 is partially exposed.

In each of the light emitting cells S1, S2, the lower semiconductor layer 155 is first exposed by mesa etching, and the light emitting cells are separated from each other by a cell isolation process. Alternatively, the light emitting cells S1, S2 may be first separated from each other through a cell isolation process, and then subjected to mesa etching to expose the lower semiconductor layers 155 of the light emitting cells S1, S2.

When the interconnect is connected to the inclined side surface, the mesa etching for exposing the upper surface of the lower semiconductor layer 155 may be omitted.

8, a second insulating layer 160b covering some regions of the first light emitting unit S1 is formed together with the second insulating layer 160b covering a side surface of the first light emitting unit S1. The first insulating layer 160a may extend to cover a region between the first light emitting unit S1 and the second light emitting unit S2. The first insulating layer 160a has openings 160hp exposing the upper semiconductor layer 159 and openings 160hn exposing the lower semiconductor layer 155 . On the other hand, the first insulating layer 160a may be connected to the second insulating layer 160b, but the present invention is not limited thereto. In some embodiments, the first insulating layer 160a may be separated from the second insulating layer 160b.

The first insulating layer 160a and the second insulating layer 160b may be simultaneously formed of silicon oxide or silicon nitride through the same process. For example, the first insulating layer 160a and the second insulating layer 160b may be formed by depositing insulating materials and then patterning by photolithography and etching.

Next, referring to FIG. 9 , a transparent electrode layer 161 is formed on the first light emitting unit S1 and the second light emitting unit S2. The transparent electrode layer 161 is formed of a conductive oxide such as indium tin oxide (ITO) or zinc oxide, or a metal layer such as Ni/Au. The transparent electrode layer 161 is connected to the upper semiconductor layer 159 through the opening 160hp and the transparent electrode layer 161 covers the second insulating layer 160b.

In addition, the transparent electrode layer 161 covers the side surfaces of the light emitting cells S1, S2. The transparent electrode layer 161 may also cover at least three side surfaces of the corresponding light emitting unit S1 or S2. Here, the transparent electrode layer 161 is formed on the outer side of the opening 160hn so that the lower semiconductor layer 155 is exposed.

On the other hand, the transparent electrode layer 161 is separated from the side surface of the light emitting cell S1 or S2 by the first insulating layer 160a. In addition, the first transparent electrode layer 161 on the first light emitting unit S1 is separated from the second transparent electrode layer 161 on the second light emitting unit S2, and the first transparent electrode layer 161 on the first light emitting unit S1 may be separated from the second transparent electrode layer 161 on the second light emitting unit S2. The second light emitting unit S2 is separated.

The transparent electrode layer 161 may be formed through a lift-off process, without being limited thereto. Alternatively, the transparent electrode layer 161 may be formed by photolithography and etching.

Referring to FIG. 10 , interconnects 165 are formed on the transparent electrode layer 161 . The interconnection 165 includes a first connection part 165p and a second connection part 165n, wherein the first connection part 165p is connected to the first transparent electrode layer 161 of the first light emitting unit S1, and the second connection part 165n is connected to the second light emitting unit The lower semiconductor layer 155 of S2. The interconnect 165 may be formed through a lift-off process.

According to this embodiment, the first insulating layer 160a and the second insulating layer 160b may be simultaneously formed, thereby simplifying the manufacturing process. In addition, the method according to the present embodiment does not include an etching process using BOE after forming the first insulating layer 160a and the second insulating layer 160b, thereby preventing the first insulating layer 160a and the second insulating layer 160a and the second insulating layer 160a and the second insulating layer Damage to the insulating layer 160b.

11 is a plan view of a light emitting diode according to another exemplary embodiment of the present invention, and FIG. 12 is a cross-sectional view taken along line B-B of FIG. 11 .

Referring to FIGS. 11 and 12 , the light emitting diode according to this embodiment is substantially similar to the light emitting diode explained with reference to FIGS. 4 and 5 except for the position of the transparent electrode layer 161 .

That is, in the embodiments shown in FIGS. 4 and 5 , the transparent electrode layer 161 is formed to cover the four side surfaces of the corresponding light emitting cell S1 or S2 and to be separated from the adjacent light emitting cells. In contrast, in this embodiment, the first transparent electrode layer 161 covers the three side surfaces of the first light emitting unit S1 while extending to cover a portion of the side surface of the second light emitting unit S2.

The first transparent electrode layer 161 may be connected to the lower semiconductor layer 155 of the second light emitting unit S2. However, the first transparent electrode layer 161 is separated from the second transparent electrode layer and is also separated from the upper semiconductor layer 159 of the second light emitting unit S2.

According to this embodiment, the transparent electrode layer 161 can be used to supply current between the adjacent light-emitting units S1 and S2, thereby further reducing the forward voltage of the light-emitting diode.

To avoid repetition, the description of the method of manufacturing the light emitting diode according to this embodiment of the present invention will be omitted.

Although various embodiments have been described above, the present invention is not limited thereto, and various modifications, changes, and substitutions may be made without departing from the scope of the present invention.

13 is a schematic plan view of a light emitting diode according to an exemplary embodiment of the present invention, (a) and (b) of FIG. 14 are cross-sectional views taken along line A-A and line B-B of FIG. 13 , respectively, and FIG. 15 is a view of 13. Schematic circuit diagram of the light-emitting diode.

13 to 15 , the light emitting diode includes a substrate 221, a plurality of light emitting cells LEC, a current blocking layer 229, a transparent electrode layer 231, an insulating protection layer 233, a first interconnection 235, a second interconnection 237, a first interconnection The electrode pad 239a and the second electrode pad 239b.

The substrate 221 is used to support the light emitting cell LEC, and may be a growth substrate for growing a nitride semiconductor layer, such as a sapphire substrate, a silicon substrate, a GaN substrate, without limitation. The substrate 221 generally refers to the substrate in the light emitting diode chip.

A plurality of light emitting cells LEC are arranged on the substrate 221 . As shown in (a) and (b) of FIG. 14 , each light emitting cell LEC includes a first conductive type semiconductor layer 223 , an active layer 225 and a second conductive type semiconductor layer 227 . Here, the first conductive type semiconductor layer 223 and the second conductive type semiconductor layer 227 may be an n-type semiconductor layer and a p-type semiconductor layer, respectively, or vice versa. The active layer 225 is placed between the first conductive type semiconductor layer 223 and the second conductive type semiconductor layer 227, and may have a single quantum well structure or a multiple quantum well structure. The material and composition of the active layer 225 are determined according to the desired wavelength of light. For example, the active layer 225 may be formed of an AlInGaN-based compound semiconductor (eg, InGaN). The first conductive type semiconductor layer 223 and the second conductive type semiconductor layer 227 are composed of an AlInGaN-based compound semiconductor (eg, GaN) having a wider band gap than that of the active layer 225 . On the other hand, a buffer layer (not shown) may be disposed between the first conductive type semiconductor layer 223 and the substrate 221 .

The first conductive type semiconductor layer 223, the active layer 225 and the second conductive type semiconductor layer 227 may be grown on the substrate 221 by metal organic chemical vapor deposition, and then patterned by photolithography and etching.

As shown in FIGS. 13 and 14( a ), the active layer 225 and the second conductive type semiconductor layer 227 may be divided from each other on a single first conductive type semiconductor layer 223 . That is, the two light emitting cells LEC may share the first conductive type semiconductor layer 223 .

The interconnects (ie, the first interconnect 235 and the second interconnect 237 ) electrically connect the light emitting cells LEC to each other. The first interconnection 235 and the second interconnection 237 connect the light emitting cells LEC placed on the different first conductive type semiconductor layers 223 to each other in series. The first interconnect 235 electrically connects the first conductive type semiconductor layer 223 of one light emitting cell to the second conductive type semiconductor layer 227 of the adjacent light emitting cell LEC.

The first interconnect 235 includes: a first connection part 235a (anode) connected to the first conductive type semiconductor layer 223; and a second connection part 235b (cathode) placed on the second conductive type semiconductor layer 227 to be electrically connected to The second conductive type semiconductor layer 227; and the interconnection portion 235c interconnecting the first connection portion 235a and the second connection portion 235b.

The second interconnection 237 includes: a first connection part 237a (common anode) connected to the first conductive type semiconductor layer 223; and a second connection part 237b (common cathode) placed on the second conductive type semiconductor layer 227 to electrically connected to the second conductive type semiconductor layer 227; and an interconnection portion 237c, interconnecting the first connection portion 237a and the second connection portion 237b.

The common anode 237a is commonly connected to the two light emitting cells LEC. For example, the common anode 237a is electrically connected to, for example, the first conductive type semiconductor layer 223 shared by the two light emitting cells LEC. On the other hand, the common cathode 237b is commonly connected to the two light emitting cells 2LEC. For example, the common cathode 237b is electrically connected to the second conductive type semiconductor layer 227 placed on the common first conductive type semiconductor layer 223 . The common cathode 237b is placed on the area between the two light emitting cells 2LEC.

Although the first interconnection member 235 and the second interconnection member 237 have been described above, it should be understood that the light emitting cells LEC may be connected to each other through various types of interconnection members. For example, similar to the interconnect in FIG. 13 that connects the first light emitting cell to two light emitting cells adjacent to the first light emitting cell, the first connection portion 235a connected to one light emitting cell LEC may pass through the interconnection portion Connected to the common cathode 237b, the common cathode 237b is commonly connected to the two light emitting cells LEC. In addition, the common anode 237a may be connected to the two second connection parts 235b, and the two first connection parts 235a may be connected to the common cathode 237b.

A plurality of series arrays are formed by interconnects 235, 237, and the plurality of series arrays are connected in parallel with each other.

On the other hand, the transparent electrode layer 231 is connected to the second conductive type semiconductor layer 227 of the light emitting cell LEC. Although some transparent electrode layers 231 are limitedly placed on the corresponding light emitting cells, other transparent electrode layers 231 may be continuously placed on two light emitting cells LEC.

The cathodes 235b, 237b may be electrically connected to the second conductive type semiconductor layer 227 through the transparent electrode layer 231. Specifically, the common cathode 237b may be electrically connected to the two light emitting cells LEC at the same time through the transparent electrode layer 231 continuously placed on the two light emitting cells.

A current blocking layer 229 is placed under the common cathode 237b. Specifically, the current blocking layer 229 is placed under the transparent electrode layer 231 to separate the transparent electrode layer 231 from the side surface of the light emitting cell 2LEC, especially from the first conductive type semiconductor layer 223 . The current blocking layer 229 may have a width greater than that of the common cathode 237b. Also, the current blocking layer 229 may partially cover the upper region of the light emitting cell LEC. Additionally, a current blocking layer (not shown) may be placed under the cathode 235b.

The current blocking layer 229 is formed of an insulating layer to prevent current crowding under the cathodes 235b, 237b. Additionally, the current blocking layer 229 may include a distributed Bragg reflector. A distributed Bragg reflector that reflects light emitted from the active layer 225 may be formed by repeatedly stacking layers having different refractive indices (eg, TiO ₂ /SiO ₂ ). Since the current blocking layer 229 includes the distributed Bragg reflector, light generated from the active layer 225 can be prevented from being absorbed into the interconnects 235 , 237 .

As shown in FIG. 13 , a portion of the current blocking layer 229 may extend to the outside of the first conductive type semiconductor layer 223 . A portion of the interconnection portion 237c may be placed on an extension of the current blocking layer 229, so the extension will reflect light traveling toward the interconnection portion 237c. On the other hand, the transparent electrode layer 231 may extend to cover the extended portion of the current blocking layer 229 . In addition, the transparent electrode layer 231 may also extend to cover a part of the adjacent first conductive type semiconductor layer 223 .

The first electrode pads 239a and the second electrode pads 239b are placed at opposite ends of the series array. The first electrode pad 239a and the second electrode pad 239b may be placed on the light emitting cells LEC at opposite sides of the series array, respectively.

The insulating protection layer 233 may substantially cover the entire light emitting diode except for the regions where the interconnects 235, 237 and the electrode pads 239a, 239b are to be formed. The insulating protective layer 233 may be formed to protect the light emitting diode from external moisture or external force.

According to this embodiment, as shown in FIG. 15 , two series arrays of light emitting cells LEC may be formed between the first electrode pad 239a and the second electrode pad 239b. In FIG. 15, one light emitting unit is placed at one end of the series array where the second electrode pad 239b is placed, and two light emitting units are placed at the other end of the series array where the first electrode pad 239a is placed. However, the present invention is not limited to this arrangement of the light emitting cells LEC. For example, one or two light emitting cells can be placed at either end of these arrays.

In addition, according to this embodiment, as indicated by a dotted line in FIG. 15 , the common cathode 237b or the interconnects 237 including the common cathode 237b are provided to an interconnection array connected in parallel with each other. As a result, the light emitting cells connected to the common cathode 237b have the same potential, thereby alleviating current crowding on a particular array.

Although this embodiment has been shown as having four light emitting cells in the tandem array, the number of light emitting cells in the tandem array is not particularly limited as long as the tandem array includes one or more light emitting cells. In addition, the number of light emitting cells may be determined in various ways as needed or in consideration of the available voltage.

In addition, this embodiment has been shown to have a series-parallel structure in which two series arrays are formed on the substrate 221 through interconnects and connected in parallel with each other. However, it should be understood that the number of tandem arrays formed on the substrate 221 is not limited thereto, and more tandem arrays may be formed on the substrate 221 .

16 is a schematic circuit diagram illustrating a light emitting diode in which four series arrays are formed according to yet another embodiment of the present invention.

16 , the light emitting cells LEC are connected to each other by interconnects to form four series arrays, which are connected in parallel to each other between the first electrode pad 239a and the second electrode pad 239b. Light emitting cells having a larger area than the light emitting cells within the tandem array may be provided at opposite ends of the tandem array. In this embodiment, two light emitting cells are provided to the first electrode pad 239a, and one light emitting cell is provided to the second electrode pad 239b. However, it should be understood that the present invention is not limited thereto and that various numbers of light emitting cells may be provided to opposite ends of the series array.

On the other hand, some of the light emitting cells LEC in adjacent series arrays are connected to each other through a common cathode 237b, and some of the light emitting cells are connected to each other through a common anode 237a. In addition, the interconnect 237 including the common cathode 237b and the common anode 237a may connect adjacent light emitting cells to each other. The positions of the common cathode 237b and the common anode 237a are indicated by dashed lines. As described with reference to FIG. 13 , the light emitting cells 2LEC including the common cathode 237b or the common anode 237a may share the first conductive type semiconductor layer 223 . In addition, all adjacent light emitting cells between the respective series arrays may share the first conductive type semiconductor layer 223 . For example, in this embodiment, the first light emitting unit, the second light emitting unit and the third light emitting unit in each series array may share the first conductive type semiconductor layer 223 .

Although this embodiment has been shown with three light emitting cells arranged in each series array, the number of light emitting cells in the series array is not particularly limited as long as the series array includes one or more light emitting cells.

While the present invention has been shown with reference to some embodiments in conjunction with the accompanying drawings, it will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. Additionally, it should be understood that some of the features of a particular embodiment may also be applied to other embodiments without departing from the spirit and scope of the invention. Therefore, it is to be understood that the embodiments are provided by way of illustration only and are given to provide a complete disclosure of the present invention and to provide those skilled in the art with a thorough understanding of the present invention. Therefore, it is intended that this invention cover modifications and variations provided they come within the scope of the claims and their equivalents.

Claims (10)

1. A light-emitting diode comprising: the first light-emitting unit and the second light-emitting unit are separated from each other on the substrate, and the first light-emitting unit includes a side surface opposite to the second light-emitting unit; a first transparent electrode layer, electrically connected to the first light-emitting unit; an interconnect to electrically connect the first light emitting unit to the second light emitting unit; and first insulating layer, wherein the first transparent electrode layer is disposed on the upper surface of the first light-emitting unit to be electrically connected to the first light-emitting unit while at least partially covering the side surface of the first light-emitting unit, a first insulating layer separates the first transparent electrode layer from the side surface of the first light emitting unit, wherein the first insulating layer includes an opening configured to expose a lower semiconductor layer of the first light emitting unit adjacent to the second light emitting unit, Wherein, the opening is disposed between the covered side surface of the first light-emitting unit and the end of the lower semiconductor layer of the first light-emitting unit, Wherein, the interconnect is directly connected to the lower semiconductor layer through the opening. 2. The light emitting diode of claim 1, further comprising: A second insulating layer is disposed between the interconnect and the first light emitting unit on the upper surface of the first light emitting unit to block current. 3. The light emitting diode of claim 2, wherein the second insulating layer is formed of the same material as that of the first insulating layer. 4. The light emitting diode of claim 2, wherein the second insulating layer is disposed under the first transparent electrode layer, and the interconnect is connected to the first transparent electrode layer. 5. The light emitting diode of claim 1, wherein the first transparent electrode layer covers at least three side surfaces of the first light emitting unit. 6. The light emitting diode of claim 5, wherein a portion of the first transparent electrode layer partially covers the side surface of the second light emitting unit. 7. The light emitting diode of claim 1, wherein each of the first light emitting unit and the second light emitting unit comprises a lower semiconductor layer, an upper semiconductor layer, and an active layer disposed between the lower semiconductor layer and the upper semiconductor layer; the first transparent electrode layer is electrically connected to the upper semiconductor layer; and The interconnect is electrically connected to the first transparent electrode layer at one end thereof, and is electrically connected to the lower semiconductor layer of the second light emitting unit at the other end thereof. 8. The light emitting diode of claim 7, wherein the interconnect is directly connected to the first transparent electrode layer without including insulating material disposed on the entire overlapping area therebetween. 9. The light emitting diode of claim 8, further comprising: a second insulating layer disposed on the upper semiconductor layer of the first light-emitting unit, Wherein, the second insulating layer is disposed under the region where the first transparent electrode layer and the interconnection are connected. 10. The light emitting diode of claim 7, wherein the first light emitting unit and the second light emitting unit have the same structure.

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