KR102451703B1 - Light emitting device - Google Patents

Abstract

An embodiment includes a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer; a first pad electrically connected to the first semiconductor layer; a second pad electrically connected to the second semiconductor layer; and at least one first electrode disposed between the first semiconductor layer and a first pad, wherein the first electrode is bent along a first region extending toward the second pad and a side surface of the second pad Disclosed is a light emitting device including a second region.

Description

Light emitting device {LIGHT EMITTING DEVICE}

The embodiment relates to a light emitting device.

A light emitting device (LIGHT EMITTING DEVICE) is a compound semiconductor device that converts electrical energy into light energy, and various colors can be realized by adjusting the composition ratio of the compound semiconductor.

The nitride semiconductor light emitting device has advantages of low power consumption, semi-permanent lifespan, fast response speed, safety, and environmental friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps. Accordingly, the application is expanding to a backlight of a liquid crystal display (LCD) display device, a white light emitting diode lighting device, a vehicle headlight, and the like.

The embodiment provides a light emitting device capable of preventing a short circuit between the N-type electrode and the P-type pad.

A light emitting device according to an embodiment includes a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer; a first pad electrically connected to the first semiconductor layer; a second pad electrically connected to the second semiconductor layer; and at least one first electrode disposed between the first semiconductor layer and a first pad, wherein the first electrode is bent along a first region extending toward the second pad and a side surface of the second pad and a second area.

The second pad includes a first surface and a second surface facing each other, and a third surface and a fourth surface connecting the first surface and the second surface and facing each other, the first region of the first electrode may extend toward the first surface, and the second region may be bent along the first surface.

The first electrode may include a third region bent along the third surface or the fourth surface.

The first electrode may include a fourth region connected to the third region and bent along the fourth surface.

The first electrode may be bent along the second pad to form a loop surrounding the second pad.

The loop may include a plurality of branch electrodes protruding toward the second pad.

According to an embodiment, it is possible to prevent a short circuit between the N-type electrode and the P-type pad even when a micro-crack is generated due to an external impact.

Various and advantageous advantages and effects of the present invention are not limited to the above, and will be more easily understood in the course of describing specific embodiments of the present invention.

1 is a plan view of a light emitting device according to an embodiment of the present invention;
Figure 2 is a cross-sectional view in the AA direction of Figure 1,
3 is a plan view of a conventional light emitting device,
Figure 4 is a cross-sectional view in the BB direction of Figure 3,
5 is a plan view of a light emitting device according to another embodiment of the present invention;
6 is a plan view of a light emitting device according to another embodiment of the present invention,
7 is a simulation result of measuring the emission distribution of the light emitting device.

Since the present invention may have various changes and may have various embodiments, specific embodiments will be illustrated and described in the drawings. However, this is not intended to limit the embodiment of the present invention to a specific embodiment, and it should be understood to include all changes, equivalents, or substitutes included in the spirit and scope of the embodiment.

Terms including an ordinal number, such as first, second, etc., may be used to describe various elements, but the elements are not limited by the terms. The above terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the present invention, the second component may be referred to as the first component, and similarly, the first component may also be referred to as the second component. and/or includes a combination of a plurality of related listed items or any of a plurality of related listed items.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the embodiments of the present invention. The singular expression includes the plural expression unless the context clearly dictates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate that a feature, number, step, operation, component, part, or combination thereof described in the specification exists, but one or more other features It should be understood that this does not preclude the possibility of the presence or addition of numbers, steps, operations, components, parts, or combinations thereof.

In the description of the embodiment, in the case where one element is described as being formed on "on or under" of another element, on (above) or below (on) or under) includes both elements in which two elements are in direct contact with each other or one or more other elements are disposed between the two elements indirectly. In addition, when expressed as "up (up) or down (on or under)", it may include the meaning of not only an upward direction but also a downward direction based on one element.

Hereinafter, the embodiment will be described in detail with reference to the accompanying drawings, but the same or corresponding components are given the same reference numerals regardless of reference numerals, and overlapping descriptions thereof will be omitted.

1 is a plan view of a light emitting device according to an embodiment of the present invention, FIG. 2 is a cross-sectional view in the A-A direction of FIG. 1 , FIG. 3 is a plan view of a conventional light emitting device, and FIG. 4 is a B-B direction cross-sectional view of FIG.

1 and 2, the light emitting device 100 according to the embodiment includes a light emitting structure 120 including a first semiconductor layer 121, an active layer 122, and a second semiconductor layer 123; The first pad 150 electrically connected to the first semiconductor layer 121 , the second pad 160 electrically connected to the second semiconductor layer 123 , and the first semiconductor layer 121 and the first pad At least one first electrode 151 disposed between 150 .

One side of the light emitting structure 120 is covered by an insulating layer, and the first pad 150 and the second pad 160 pass through the insulating layer to the first semiconductor layer 121 and the second semiconductor layer 122, respectively. can be connected with

A plurality of first electrodes 151 are disposed on the second pad 150 and include sub-electrodes 152 electrically connected to each other. The sub-electrode 152 connected to the outermost first electrode 151 includes a first region 152a extending toward the second pad 160 and a second bent along side surfaces of the second pad 160 . regions 152b and 152c. That is, the sub-electrode 152 does not overlap the second pad 160 in a plan view. The first electrode 151 and the sub-electrode 152 may have a Cr/Ni/Au layer structure, and each may have a thickness of 30/100/700 nm.

The second pad 160 may have a rectangular shape including four side surfaces. The second pad 160 has a first surface 160a and a second surface 160b that face each other, and a third surface 160c that connects the first surface 160a and the second surface 160b and faces each other. and a fourth surface 160d. The width of the second pad 160 may be 400 um to 800 um.

The first region 152a of the sub-electrode 152 extends toward the first surface 160a. The second regions 152b and 152c are bent along the first surface 160a, between the third surface 160c and the edge 100a of the light emitting device, or the fourth surface 160d and the edge 100a of the light emitting device ) can be placed between The sub-electrode 152 may have a width of 10 μm to 20 μm and a thickness of 0.1 μm to 1.0 μm.

For example, the distance between the second regions 152b and 152c and the second pad 160 may be smaller than the distance between the second regions 152b and 152c and the edge 100a of the light emitting device, but is not limited thereto.

The sub-electrode 152 may further include a third region 152d that is bent along the third surface 160c or the fourth surface 160d and surrounds the second surface 160b.

3 and 4, when the N-type electrode 2 is extended and disposed on the P-type pad 1, if a crack occurs in the insulating layer due to an external impact, etc., the N-type electrode 2 and the P-type pad (1) is short-circuited, and device failure may occur. Also, when cracks occur in the P-type pad 1 , solder diffusion into the chip may destroy chip characteristics.

In the light emitting device according to the embodiment, since the first electrode 151 and the second pad 160 do not overlap on a plane surface, a short circuit between the first electrode 151 and the second pad 160 even when a crack occurs due to an external impact, etc. can be prevented.

Referring to FIG. 5 , the sub-electrode 152 may have a shape that entirely surrounds the side surface of the second pad 160 , or may have a shape that surrounds only some side surfaces 160b and 160c.

Referring to FIG. 6 , the first electrodes 151 may include branch electrodes 153 protruding toward the second pad 160 . The width of the sub-electrode 152 may be 10 μm to 20 μm, and the width of the branch electrode 153 may be 3 μm to 10 μm. The distance between the branch electrodes 153 facing each other may be within 600 nm.

In the second pad 160 , a groove 162 may be formed in a portion corresponding to the branch electrode. Accordingly, the branch electrode 153 and the second pad 160 do not overlap in plan view.

Referring back to FIG. 2 , the substrate 110 includes a conductive substrate or an insulating substrate. The substrate 110 may be a material suitable for semiconductor material growth or a carrier wafer. The substrate 110 may be formed of a material selected from among sapphire (Al ₂ O ₃ ), GaN, SiC, GaAs, GaN, ZnO, Si, GaP, InP, and Ge, but is not limited thereto.

The light emitting structure 120 is disposed on one surface 111 of the substrate 110 , and includes a first semiconductor layer 121 , an active layer 122 , and a second semiconductor layer 123 . The light emitting structure 120 may be separated into a plurality in the process of cutting the substrate 110 .

The first semiconductor layer 121 may be a group III-V or group II-VI compound semiconductor, and the first semiconductor layer 121 may be doped with a first dopant. The first semiconductor layer 121 is a semiconductor material having a composition formula of In _x1 Al _y1 Ga ₁ -x1 _-y1 N (0≤x1≤1, 0≤y1≤1, 0≤x1+y1≤1), for example, It may be selected from GaN, AlGaN, InGaN, InAlGaN, and the like. In addition, the first dopant may be an n-type dopant such as Si, Ge, Sn, Se, or Te. When the first dopant is an n-type dopant, the first semiconductor layer 121 doped with the first dopant may be an n-type semiconductor layer.

The active layer 122 is a layer in which electrons (or holes) injected through the first semiconductor layer 121 and holes (or electrons) injected through the second semiconductor layer 123 meet. The active layer 122 may transition to a low energy level as electrons and holes recombine, and may generate light having a corresponding wavelength. In this embodiment, there is no limitation on the emission wavelength.

The active layer 122 may have any one of a single well structure, a multi-well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, or a quantum wire structure, and the active layer 122 may have a structure. The structure of is not limited thereto.

The second semiconductor layer 123 may be implemented with a group III-V or group II-VI compound semiconductor, and the second semiconductor layer 123 may be doped with a second dopant. The second semiconductor layer 123 is a semiconductor material having a composition formula of In _x5 Al _y2 Ga _1-x5-y2 N (0≤x5≤1, 0≤y2≤1, 0≤x5+y2≤1) or AlInN, AlGaAs , GaP, GaAs, GaAsP, may be formed of a material selected from AlGaInP. When the second dopant is a p-type dopant such as Mg, Zn, Ca, Sr, or Ba, the second semiconductor layer 123 doped with the second dopant may be a p-type semiconductor layer.

Although not shown, an electron blocking layer EBL may be disposed between the active layer 122 and the second semiconductor layer 123 . The electron blocking layer blocks the flow of electrons supplied from the first semiconductor layer 121 from escaping to the second semiconductor layer 123 , thereby increasing the probability of electrons and holes recombination in the active layer 122 .

In the light emitting structure 120 , a first groove H1 through which the first semiconductor layer 121 is exposed may be formed through the second semiconductor layer 123 and the active layer 122 . The first semiconductor layer 121 may also be partially etched by the first groove H1 . The first groove H1 may be plural. A first electrode 151 may be disposed in the first groove H1 to be electrically connected to the first semiconductor layer 121 . A second electrode 131 may be disposed under the second semiconductor layer 123 .

The first electrode 151 and the second electrode 131 include indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), and indium gallium zinc oxide (IGZO). ), indium gallium tin oxide (IGTO), aluminum zinc oxide (AZO), antimony tin oxide (ATO), gallium zinc oxide (GZO), SnO, InO, INZnO, ZnO, IrOx, RuOx, NiO, Ti, Al, Ni , Cr and optional compounds or alloys thereof, and may be formed of at least one layer. The thickness of the ohmic electrode is not particularly limited.

The protective layer 141 may insulate the first electrode 151 from the active layer 122 and the second semiconductor layer 123 . The protective layer 141 may be formed entirely on the light emitting structure 120 except for the region where the first electrode 151 and the second electrode 131 are formed.

The protective layer 141 may include an insulating material or an insulating resin formed of at least one of oxide, nitride, fluoride, and sulfide having at least one of Al, Cr, Si, Ti, Zn, and Zr. The protective layer 141 may be selectively formed from, for example, SiO2, Si3N4, Al2O3, and TiO2. The protective layer 141 may be formed as a single layer or a multilayer, but is not limited thereto.

The reflective electrode layer 132 may be disposed on the second electrode 131 . The reflective electrode layer 132 may be formed of a metallic or non-metallic material. The metallic reflective electrode layer 132 includes In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, Nb, Al , Ni, Cu, and may include any one of a metal selected from WTi.

The first insulating layer 142 entirely covers the light emitting structure 120 on which the reflective electrode layer 132 is disposed. The first insulating layer 142 may include an insulating material or an insulating resin formed of at least one of oxide, nitride, fluoride, and sulfide having at least one of Al, Cr, Si, Ti, Zn, and Zr. The first insulating layer 142 may be selectively formed from, for example, SiO2, Si3N4, Al2O3, and TiO2. The first insulating layer 142 may be formed as a single layer or a multilayer, but is not limited thereto.

The first insulating layer 142 may be a reflective layer. Specifically, the first insulating layer 142 includes a structure in which two or more pairs of a first layer having a first refractive index and a second layer having a second refractive index are alternately stacked, the first layer and the second layer having a refractive index It can be formed of a conductive or insulating material that is between 1.5 and 2.4. This structure may be a distributed bragg reflection (DBR) structure. In addition, it may have a structure in which a dielectric layer having a low refractive index and a metal layer are stacked (omnidirectional reflector).

Due to this configuration, most of the light emitted from the active layer 122 toward the second semiconductor layer 123 may be reflected toward the substrate 110 . Accordingly, the reflection efficiency can be increased, and the light extraction efficiency can be improved.

The first pad 150 may pass through the first insulating layer 142 to be electrically connected to the first electrode 151 . The area of the first electrode 151 increases as it approaches the substrate 110 , whereas the area of the first pad 150 decreases as it approaches the substrate 110 .

The second pad 160 may pass through the first insulating layer 142 to be electrically connected to the second electrode 131 and the reflective electrode layer 132 .

The first pad 150 and the second pad 160 include In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, It may include any one of a metal selected from Cr, Mo, Nb, Al, Ni, Cu, and WTi.

The light emitting device of the embodiment may further include an optical member such as a light guide plate, a prism sheet, and a diffusion sheet to function as a backlight unit. In addition, the light emitting device of the embodiment may be further applied to a display device, a lighting device, and an indicator device.

In this case, the display device may include a bottom cover, a reflector, a light emitting module, a light guide plate, an optical sheet, a display panel, an image signal output circuit, and a color filter. The bottom cover, the reflector, the light emitting module, the light guide plate, and the optical sheet may form a backlight unit.

The reflector is disposed on the bottom cover, and the light emitting module emits light. The light guide plate is disposed in front of the reflection plate to guide light emitted from the light emitting module to the front, and the optical sheet includes a prism sheet and the like, and is disposed in front of the light guide plate. A display panel is disposed in front of the optical sheet, an image signal output circuit supplies an image signal to the display panel, and a color filter is disposed in front of the display panel.

In addition, the lighting device may include a light source module including a substrate and the light emitting device of the embodiment, a heat dissipation unit for dissipating heat of the light source module, and a power supply unit for processing or converting an electrical signal provided from the outside and providing it to the light source module. . Furthermore, the lighting device may include a lamp, a head lamp, or a street lamp.

The embodiments of the present invention described above are not limited to the above-described embodiments and the accompanying drawings, and it is a technical field to which the embodiments of the present invention pertain that various substitutions, modifications and changes are possible within the scope without departing from the technical spirit of the embodiments. It will be clear to those with prior knowledge in

Claims (6)

a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer;
a first pad electrically connected to the first semiconductor layer;
a second pad electrically connected to the second semiconductor layer; and
at least one first electrode disposed between the first semiconductor layer and the first pad;
the first electrode includes a first region extending toward the second pad and a second region bent along a side surface of the second pad;
The first region and the second region of the first electrode do not overlap the second pad in a thickness direction of the light emitting structure. The method of claim 1,
The second pad includes a first surface and a second surface facing each other, and a third surface and a fourth surface connecting the first surface and the second surface and facing each other,
A first region of the first electrode extends toward the first surface, and the second region is bent along the first surface. 3. The method of claim 2,
The first electrode includes a third region bent along the third surface or the fourth surface. 4. The method of claim 3,
and the first electrode is connected to the third region and includes a fourth region bent along the fourth surface. The method of claim 1,
The first electrode is bent along the second pad to form a loop surrounding the second pad. 6. The method of claim 5,
The loop includes a plurality of branched electrodes protruding toward the second pad.

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