KR102413447B1 - 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 reflective electrode layer disposed on the second semiconductor layer; a first insulating layer covering the light emitting structure and the reflective electrode layer; a first electrode pad connected to the first semiconductor layer through the first insulating layer; a second electrode pad passing through the first insulating layer and connected to the second semiconductor layer; and a second insulating layer including a first region covering a side surface of the first insulating layer.

Description

Light emitting device {LIGHT EMITTING DEVICE}

The embodiment relates to a light emitting device.

A light emitting diode (LED) 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, applications are being expanded to backlights of liquid crystal display (LCD) display devices, lighting devices, and automobile headlights.

In general, a light emitting device may have a reflective electrode disposed under the light emitting structure to improve light extraction efficiency. However, there is a problem in that the reflective electrode is peeled off from the light emitting structure due to thermal stress or the like, resulting in poor electrical reliability.

The embodiment provides a light emitting device having excellent electrical characteristics.

A light emitting device according to an embodiment of the present invention includes: a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer; a reflective electrode layer disposed on the second semiconductor layer; a first insulating layer covering the light emitting structure and the reflective electrode layer; a first electrode pad connected to the first semiconductor layer through the first insulating layer; a second electrode pad passing through the first insulating layer and connected to the second semiconductor layer; and a second insulating layer including a first region covering a side surface of the first insulating layer.

The second insulating layer may reflect light emitted from the light emitting structure.

The first insulating layer may reflect light emitted from the light emitting structure.

A substrate supporting the light emitting structure may be included, and the second insulating layer may include a second region covering a side surface of the substrate.

The second insulating layer may include a third region covering side surfaces of the first electrode pad and the second electrode pad.

The third region may include an extension portion extending to the bottom surface of the first electrode pad and the second electrode pad.

An area in which the extension part covers the bottom surfaces of the first electrode pad and the second electrode pad may be 5% to 30% of the total area of the bottom surface.

The second insulating layer includes a second region covering a side surface of the substrate supporting the light emitting structure, and a third region covering side surfaces of the first electrode pad and the second electrode pad, the first region; The thickness of the second region and the third region may be the same.

The second insulating layer may include a high refractive index layer and a low refractive index layer alternately stacked.

The second insulating layer may have a reflectance of 96% or more with respect to light in a wavelength band of 450 nm.

A light emitting device package according to an embodiment of the present invention includes: a light emitting device; and a wavelength conversion layer for converting the light emitted from the light emitting device into white light, wherein the light emitting device includes: a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer; a reflective electrode layer disposed on the second semiconductor layer; a first insulating layer covering the light emitting structure and the reflective electrode layer; a first electrode pad connected to the first semiconductor layer through the first insulating layer; a second electrode pad passing through the first insulating layer and connected to the second semiconductor layer; and a second insulating layer including a first region covering a side surface of the first insulating layer.

According to an embodiment, peeling of the reflective electrode is improved, and thus electrical characteristics are improved.

Various and beneficial 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 view showing a light emitting device according to an embodiment of the present invention,
2 is a graph measuring a change in current according to an increase in voltage applied to a light emitting device;
3 is an enlarged view of part A of FIG. 1;
4 is a graph of measuring the reflectance of the second insulating layer;
5 is a view for explaining an area in which the second insulating layer covers the electrode pad;
6 is a view showing a light emitting device package according to an embodiment of the present invention,
7A to 7F are flowcharts for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention.

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 in "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 view showing a light emitting device according to an embodiment of the present invention, FIG. 2 is a graph measuring current change according to an increase in voltage applied to the light emitting device, and FIG. 3 is an enlarged view of part A of FIG. , FIG. 4 is a graph measuring the reflectance of the second insulating layer, and FIG. 5 is a view for explaining an area of the second insulating layer covering the electrode pad.

Referring to FIG. 1 , the light emitting device 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 , and a second semiconductor layer ( The reflective electrode layer 132 disposed on the 123 , the first insulating layer 142 covering the reflective electrode layer 132 , and the first passing through the first insulating layer 142 and connected to the first semiconductor layer 121 . The electrode pad 150 , the second electrode pad 160 connected to the second semiconductor layer 123 through the first insulating layer 142 , and the second insulating layer covering the entire side surface of the light emitting device 100 . (170).

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. If necessary, the substrate 110 may be removed.

The substrate 110 may include a plurality of light extraction structures 112 formed on one surface 111 . The plurality of light extraction structures 112 may have different heights.

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 as 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 recombination of electrons and holes 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 ohmic electrode 151 may be disposed in the first groove H1 to be electrically connected to the first semiconductor layer 121 . A second ohmic electrode 131 may be disposed under the second semiconductor layer 123 .

The first ohmic electrode 151 and the second ohmic electrode 131 are indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc tin oxide (IZTO), indium aluminum zinc oxide (IAZO), and indium gallium (IGZO). zinc oxide), 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 ohmic 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 ohmic electrode 151 and the second ohmic 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 ohmic 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, and the first layer and the second layer have 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 electrode pad 150 may pass through the first insulating layer 142 to be electrically connected to the first ohmic electrode 151 . The area of the first ohmic electrode 151 increases as it approaches the substrate 110 , whereas the area of the first electrode pad 150 decreases as it approaches the substrate 110 .

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

The first electrode pad 150 and the second electrode pad 160 include 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 second insulating layer 170 may cover the entire side surface of the light emitting device to which the first electrode pad 150 and the second electrode pad 160 are connected. The second insulating layer 170 may be selectively formed of, for example, at least one of SiO2, Si3N4, Al2O3, and TiO2.

When power is applied to the light emitting device, current crowding occurs in the outer part of the chip and high heat is generated. Accordingly, the reflective electrode layer 132 may be peeled off from the outside of the chip. Also, when a crack occurs in the first insulating layer 142 , the reflective electrode layer 132 may be easily peeled off.

According to an embodiment, since the second insulating layer 170 entirely covers the side surface of the light emitting device, the light emitting structure 120 and the reflective electrode layer 132 together with the first insulating layer 142 can be double protected. Accordingly, it is possible to prevent the reflective electrode layer 132 from being peeled off.

The second insulating layer 170 includes a first region 171 covering the side surface of the first insulating layer 142 , a second region 172 covering the side surface of the substrate 110 , and first and second electrodes. A third region 173 covering side surfaces of the pads 150 and 160 is included.

As described above, the first region 171 doubles the reflective electrode layer 132 to prevent the reflective electrode layer from peeling off even when a high current is injected. In addition, the second insulating layer 170 may reflect light emitted from the light emitting structure 120 upward.

The second region 172 of the second insulating layer 170 covers the side surface of the substrate 110 . Accordingly, it is possible to prevent cracks from occurring between the substrate 110 and the light emitting structure 120 . When the second insulating layer 170 is a reflective layer, the light emitted from the light emitting structure 120 may be condensed.

The third region 173 may cover side surfaces of the first electrode pad 150 and the second electrode pad 160 . Accordingly, it is possible to prevent the separation of the interface between the first and second electrode pads 160 and the first insulating layer 142 .

The third region 173 may include an extension portion 173a extending to the bottom surface of the first electrode pad 150 and the second electrode pad 160 . When the first and second electrode pads 150 and 160 are mounted on the circuit board, the extension 173a is fixed between the first and second electrode pads 150 and 160 and the circuit board, so that the second insulating layer 170 . and the lifting phenomenon between the first and second electrode pads 150 and 160 may be improved.

Referring to FIG. 2 , in the case of the structure S1 without the second insulating layer 170 , it can be seen that the current value gradually increases as the voltage increases. This is due to the reflective electrode layer being peeled off by the high current. However, in the case of the embodiment (S2), it can be seen that even when the voltage exceeds about 2.0V, it has a relatively constant current value. Accordingly, it can be seen that the peeling of the reflective electrode layer is improved by the second insulating layer 170 .

Referring to FIG. 3 , the second insulating layer 170 may have a distributed bragg reflection (DBR) structure including a structure in which a high refractive index layer 170a and a low refractive index layer 170b are alternately stacked.

For example, the high refractive index layer 170a may be TiO2, and the low refractive index layer 170b may be SiO2. The second insulating layer 170 may include about 3 to 40 pairs of a high refractive index layer 170a and a low refractive index layer 170b. The thickness of each layer may be between about 50 nm and 100 nm. Accordingly, the total thickness of the second insulating layer 170 may be about 10 μm to 30 μm. Referring to FIG. 4 , the second insulating layer 170 may reflect 96% or more of light in a wavelength band of 450 nm. The first insulating layer 142 and the second insulating layer 170 may be DBR layers having the same structure.

Referring to FIG. 5 , the area in which the extension part 173a covers the bottom surfaces of the first electrode pad 150 and the second electrode pad 160 may be 5% to 30% of the total area of the bottom surface. When the cover area is less than 5%, it becomes difficult to stably attach the second insulating layer 170, and when the cover area exceeds 30%, the exposed areas of the first electrode pad 150 and the second electrode pad 160 become small and the resistance this can be higher Accordingly, the operating voltage may be increased.

6 is a view showing a light emitting device package according to an embodiment of the present invention.

Referring to FIG. 6 , a wavelength conversion layer 180 may be disposed on the substrate 110 . The blue wavelength light emitted from the active layer 122 by the wavelength conversion layer 180 may be converted into white light. The package having this structure may be a chip scale package (CSP).

In the wavelength conversion layer 180 , a phosphor or quantum dots may be dispersed in a polymer resin. The type of the phosphor is not particularly limited. In order to realize white light, at least one of YAG-based, TAG-based, Silicate-based, Sulfide-based, and Nitride-based fluorescent materials may be included.

When the substrate is mounted, since the extension 173a is fixed between the first and second electrode pads 150 and 160 and the circuit board 10 , the second insulating layer 170 and the first and second electrode pads 150 , 160) can improve the floating phenomenon between. Also, the second insulating layer 170 may protect the first insulating layer 142 and the reflective electrode layer 132 when the first and second electrode pads 150 and 160 and the circuit board 10 are in contact.

7A to 7F are flowcharts for explaining a method of manufacturing a light emitting device according to an embodiment of the present invention.

Referring to FIG. 7A , a first semiconductor layer 121 , an active layer 122 , and a second semiconductor layer 123 are sequentially formed on a substrate 110 . Thereafter, at least one first groove H1 exposing the first semiconductor layer 121 may be formed by etching the second semiconductor layer 123 and the active layer 122 .

Referring to FIG. 7B , after the protective layer 141 is formed on the light emitting structure 120 in which the first groove H1 is formed, a portion is removed to form the first ohmic electrode 151 and the second ohmic electrode 131 . can do.

A reflective electrode layer 142 is formed on the second ohmic electrode 131 . The reflective electrode layer 142 may be formed in the order of Ag/Ni/Ti by sputtering. In this case, a plasma cleaning process may be performed to increase the bonding strength between the second ohmic electrode 131 and the reflective electrode layer 142 .

Thereafter, the first insulating layer 142 is formed as a whole thereon. There is no limitation on the method of forming the respective layers. A mask pattern may be used or a photoresist may be used.

Referring to FIG. 7C , a portion of the first insulating layer 142 is etched, and a first electrode pad 150 and a second electrode pad 160 are respectively formed thereon.

Referring to FIG. 7D , the second insulating layer 170 is formed entirely on the side surface of the light emitting device on which the first electrode pad 150 and the second electrode pad 160 are disposed. A method of forming the second insulating layer 170 is not limited. Thereafter, the second insulating layer formed on the bottom surfaces of the first and second electrode pads 150 and 160 may be partially removed. According to this configuration, it is possible to solve the problem that the reflective electrode layer is peeled off due to the current concentration phenomenon, and at the same time, it is possible to improve the extraction efficiency of light emitted from the light emitting structure.

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 reflection plate, 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 the 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 without departing from the technical spirit of the embodiments. It will be clear to those with prior knowledge in

110: substrate
120: light emitting structure
121: first semiconductor layer
122: active layer
123: second semiconductor layer
131: second ohmic electrode
132: reflective electrode layer
141: protective layer
142: first insulating layer
150: first electrode pad
151: first ohmic electrode
160: second electrode pad
170: second insulating layer

Claims (11)

a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer;
a protective layer covering side surfaces of the first semiconductor layer, the active layer, and the second semiconductor layer;
a reflective electrode layer passing through the protective layer and disposed on the second semiconductor layer;
a first insulating layer covering the light emitting structure and the reflective electrode layer;
a first electrode pad connected to the first semiconductor layer through the first insulating layer;
a second electrode pad passing through the first insulating layer and connected to the second semiconductor layer; and
and a second insulating layer including a first region covering a side surface of the first insulating layer and a side surface of the passivation layer.
According to claim 1,
The second insulating layer is a light emitting device that reflects the light emitted from the light emitting structure.
3. The method of claim 2,
The first insulating layer is a light emitting device that reflects the light emitted from the light emitting structure.
According to claim 1,
and a substrate supporting the light emitting structure,
The second insulating layer may include a second region covering a side surface of the substrate.
According to claim 1,
The second insulating layer may include a third region covering side surfaces of the first electrode pad and the second electrode pad.
6. The method of claim 5,
The third region is a light emitting device including an extension portion extending to the bottom surface of the first electrode pad and the second electrode pad.
7. The method of claim 6,
An area in which the extension portion covers the bottom surfaces of the first electrode pad and the second electrode pad is 5% to 30% of the total area of the bottom surface.
According to claim 1,
The second insulating layer includes a second region covering a side surface of the substrate supporting the light emitting structure, and a third region covering side surfaces of the first electrode pad and the second electrode pad,
The first region, the second region, and the third region have the same thickness.
9. The method of claim 8,
The second insulating layer is a light emitting device comprising a high refractive index layer and a low refractive index layer alternately stacked.
9. The method of claim 8,
The second insulating layer is a light emitting device having a reflectance of 96% or more with respect to light in a wavelength band of 450 nm.
light emitting device; and
and a wavelength conversion layer for converting the light emitted from the light emitting device into white light,
The light emitting device is
a light emitting structure including a first semiconductor layer, an active layer, and a second semiconductor layer;
a protective layer covering side surfaces of the first semiconductor layer, the active layer, and the second semiconductor layer;
a reflective electrode layer passing through the protective layer and disposed on the second semiconductor layer;
a first insulating layer covering the light emitting structure and the reflective electrode layer;
a first electrode pad connected to the first semiconductor layer through the first insulating layer;
a second electrode pad passing through the first insulating layer and connected to the second semiconductor layer; and
and a second insulating layer including a first region covering a side surface of the first insulating layer and a side surface of the protective layer.

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