KR20170083353A - 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 penetrating the first insulating layer and connected to the first semiconductor layer; A second electrode pad penetrating 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

[0001] LIGHT EMITTING DEVICE [0002]

An embodiment relates to a light emitting element.

Light emitting diodes (LEDs) are compound semiconductor devices that convert electrical energy into light energy. By controlling the composition ratio of compound semiconductors, various colors can be realized.

The nitride semiconductor light emitting device has advantages of low power consumption, semi-permanent lifetime, fast response speed, safety, and environmental friendliness compared to conventional light sources such as fluorescent lamps and incandescent lamps. Accordingly, application to backlights of LCD (Liquid Crystal Display) displays, lighting devices, and automotive headlights has been expanded.

In general, the light emitting device may have a reflective electrode disposed under the light emitting structure to improve light extraction efficiency. However, there is a problem that the reflective electrode is peeled off from the light emitting structure due to thermal stress or the like, thereby deteriorating the 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 penetrating the first insulating layer and connected to the first semiconductor layer; A second electrode pad penetrating 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, 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 the side surfaces of the first electrode pad and the second electrode pad.

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

The area of the extending portion covering the bottom surface of the first electrode pad and the second electrode pad may be 5% to 30% of the total area of the bottom surface.

Wherein 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 a side surface of the first electrode pad and the second electrode pad, The second region, and the third region may be the same.

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

The second insulation layer may have a reflectance of 96% or more for light having a wavelength of 450 nm.

A light emitting device package according to an embodiment of the present invention includes: a light emitting element; And a wavelength conversion layer converting light emitted from the light emitting device into white light, wherein the light emitting device includes 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 penetrating the first insulating layer and connected to the first semiconductor layer; A second electrode pad penetrating 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 the embodiment, the peeling of the reflective electrode is improved and the electrical characteristics are improved.

The various and advantageous advantages and effects of the present invention are not limited to the above description, and can be more easily understood in the course of describing a specific embodiment of the present invention.

1 is a view illustrating a light emitting device according to an embodiment of the present invention,
2 is a graph showing a change in current due to an increase in the voltage applied to the light emitting device,
3 is an enlarged view of a portion A in Fig. 1,
4 is a graph showing the reflectance of the second insulating layer,
5 is a view for explaining an area where the second insulating layer covers the electrode pad,
6 is a view illustrating a light emitting device package according to an embodiment of the present invention,
7A to 7F are flowcharts illustrating a method of manufacturing a light emitting device according to an embodiment of the present invention.

While the invention is susceptible to various modifications and alternative forms, specific embodiments thereof are shown by way of example in the drawings and will herein be described in detail. It should be understood, however, that the embodiments of the present invention are not intended to be limited to the specific embodiments but include all modifications, equivalents, and alternatives falling within the spirit and scope of the embodiments.

Terms including ordinals, such as first, second, etc., may be used to describe various elements, but the elements are not limited to these terms. The terms are used only for the purpose of distinguishing one component from another. For example, without departing from the scope of the embodiments, the second component may be referred to as a first component, and similarly, the first component may also be referred to as a second component. And / or < / RTI > includes any combination of a plurality of related listed items or any of a plurality of related listed items.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of the invention. The singular expressions include plural expressions unless the context clearly dictates otherwise. In the present application, the terms "comprises" or "having" and the like are used to specify that there is a feature, a number, a step, an operation, an element, a component or a combination thereof described in the specification, But do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, or combinations thereof.

In the description of the embodiments, in the case where one element is described as being formed "on or under" another element, the upper (upper) or lower (lower) or under are all such that two elements are in direct contact with each other or one or more other elements are indirectly formed between the two elements. Also, when expressed as "on or under", it may include not only an upward direction but also a downward direction with respect to one element.

Hereinafter, embodiments will be described in detail with reference to the accompanying drawings, wherein like or corresponding elements are denoted by the same reference numerals, and redundant description thereof will be omitted.

FIG. 1 is a graph showing a light emitting device according to an embodiment of the present invention. FIG. 2 is a graph illustrating a current change according to an increase in a voltage applied to a light emitting device. FIG. , FIG. 4 is a graph showing the reflectance of the second insulating layer, and FIG. 5 is a view for explaining the area of the second insulating layer covering the electrode pad.

1, a light emitting device according to an embodiment includes a light emitting structure 120 including a first semiconductor layer 121, an active layer 122, and a second semiconductor layer 123, A first insulating layer 142 covering the reflective electrode layer 132 disposed on the first semiconductor layer 121 and a reflective electrode layer 132 disposed on the first semiconductor layer 121 through the first insulating layer 142, A second electrode pad 160 which is connected to the second semiconductor layer 123 through the electrode pad 150 and the first insulating layer 142 and a second electrode pad 160 which covers 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 the group consisting of sapphire (Al ₂ O ₃ ), GaN, SiC, GaAs, GaN, ZnO, Si, GaP, InP and Ge. The substrate 110 can be removed as needed.

The substrate 110 may include a plurality of light extraction structures 112 formed on one side 111 thereof. The plurality of light extracting 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 divided into a plurality of portions in the process of cutting the substrate 110.

The first semiconductor layer 121 may be a compound semiconductor such as a III-V group or a II-VI group, 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 _{x 1} Al _{y 1} Ga ₁ -x ₁ -y ₁ N (0? X _{1? 1} , 0? Y _{1? 1} , 0? X 1 + _{y 1? 1} ) GaN, AlGaN, InGaN, InAlGaN, and the like. 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 where 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 transitions to a low energy level as electrons and holes are recombined, and light having a wavelength corresponding thereto can be generated. There is no limitation on the emission wavelength in this embodiment.

The active layer 122 may have any one of a single well structure, a multiple well structure, a single quantum well structure, a multi quantum well (MQW) structure, a quantum dot structure, Is not limited thereto.

The second semiconductor layer 123 may be formed of a compound semiconductor such as a group III-V or II-VI group, and the second semiconductor layer 123 may be doped with a second dopant. The second semiconductor layer 123 may be a semiconductor material having a composition formula of In _{x 5} Al _{y 2} Ga _{1 -x5-y 2} N (0? X 5? 1, 0? Y 2? 1, 0? X 5 + y 2? 1) , GaP, GaAs, GaAsP, and 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 can block the flow of electrons supplied from the first semiconductor layer 121 to the second semiconductor layer 123 and increase the probability of recombination of electrons and holes in the active layer 122.

The light emitting structure 120 may have a first groove H1 through which the first semiconductor layer 121 is exposed through the second semiconductor layer 123 and the active layer 122. [ The first semiconductor layer 121 can also be partially etched by the first trench H1. The first grooves H1 may be plural. A first ohmic electrode 151 may be disposed in the first groove H1 and 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 may be formed of indium tin oxide (ITO), indium zinc oxide (IZO), indium zinc oxide (IZTO), indium aluminum zinc oxide (IAZO) zinc oxide, IGTO, aluminum zinc oxide, ATO, gallium zinc oxide, SnO, InO, INZnO, ZnO, IrOx, RuOx, NiO, Ti, Al , Ni, Cr, and their optional compounds or alloys, and may be formed of at least one layer. The thickness of the ohmic electrode is not particularly limited.

The protective layer 141 may isolate the first ohmic electrode 151 from the active layer 122 and the second semiconductor layer 123. The protective layer 141 may be formed entirely in the light emitting structure 120 except for a 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, for example, of 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 may be formed of a metal such as In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, W, Ti, Ag, Cr, Mo, , Ni, Cu, and WTi.

The first insulating layer 142 entirely covers the light emitting structure 120 in 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 oxides, nitrides, fluorides, and sulfides having at least one of Al, Cr, Si, Ti, Zn, and Zr. The first insulating layer 142 may be selectively formed of, for example, SiO2, Si3N4, Al2O3, or 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 a first layer having a first refractive index and a second layer having a second refractive index are alternately stacked two or more layers, and the first layer and the second layer have a refractive index And may be formed of a conductive or insulating material between 1.5 and 2.4. Such a structure may be a DBR (distributed bragg reflection) structure. Further, it may be a structure in which a dielectric layer having a low refractive index and a metal layer are laminated (Omnidirectional Reflector).

With this structure, most of the light emitted from the active layer 122 toward the second semiconductor layer 123 can be reflected toward the substrate 110 side. Therefore, the reflection efficiency can be increased and the light extraction efficiency can be improved.

The first electrode pad 150 may be electrically connected to the first ohmic electrode 151 through the first insulating layer 142. The area of the first ohmic electrode 151 increases as the proximity of the first ohmic electrode 151 to the substrate 110 decreases while the area of the first electrode pad 150 decreases as the proximity of the first electrode pad 150 to the substrate 110 increases.

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

The first electrode pad 150 and the second electrode pad 160 may be formed of a material selected from the group consisting of In, Co, Si, Ge, Au, Pd, Pt, Ru, Re, Mg, Zn, Hf, Ta, Rh, Ir, Ag, Cr, Mo, Nb, Al, Ni, Cu, and 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. At least one of SiO 2, Si 3 N 4, Al 2 O 3, and TiO 2 may be selectively formed in the second insulating layer 170.

When power is applied to the light emitting device, current crowding occurs at the outer portion of the chip, and high heat is generated. Therefore, the reflective electrode layer 132 can be peeled from the outer periphery of the chip. In addition, when the first insulating layer 142 is cracked, the reflective electrode layer 132 can be easily peeled off.

The second insulating layer 170 covers the entire side surface of the light emitting device so that the light emitting structure 120 and the reflective electrode layer 132 can be doubly protected together with the first insulating layer 142. [ Therefore, it is possible to prevent the reflection electrode layer 132 from peeling off.

The second insulating layer 170 includes a first region 171 covering a side surface of the first insulating layer 142, a second region 172 covering a side surface of the substrate 110, And a third region 173 covering the sides of the pads 150 and 160.

As described above, the first region 171 covers the reflective electrode layer 132 in a duplex manner, thereby preventing the reflective electrode layer from being peeled off even when a high current is injected. The second insulating layer 170 may reflect the 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. Therefore, cracks can be prevented from occurring between the substrate 110 and the light emitting structure 120. When the second insulating layer 170 is a reflective layer, light emitted from the light emitting structure 120 can be condensed.

The third region 173 may cover the sides of the first electrode pad 150 and the second electrode pad 160. Accordingly, it is possible to prevent the interface between the first and second electrode pads 160 and the first insulating layer 142 from being separated from each other.

The third region 173 may include an extended 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 extended portion 173a is fixed between the first and second electrode pads 150 and 160 and the circuit board, And the first and second electrode pads 150 and 160 can be improved.

Referring to FIG. 2, in the case of the structure S1 in which the second insulating layer 170 is not provided, the current value gradually increases as the voltage rises. This is caused by the fact that the reflective electrode layer is peeled off by a high current. However, it can be seen that, in the case of the embodiment (S2), even if the voltage exceeds about 2.0 V, the current has a relatively constant current value. Therefore, 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 be 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.

In one 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 be formed of about 3 to 40 pairs of the high-refractive index layer 170a and the low-refractive index layer 170b. The thickness of each layer may be between about 50 nm and 100 nm. Thus, the total thickness of the second insulating layer 170 may be between about 10 um and 30 um. Referring to FIG. 4, the second insulating layer 170 can reflect 96% or more of light having a wavelength of 450 nm. The first insulating layer 142 and the second insulating layer 170 may be DBR layers having the same structure.

5, the area of the extension 173a covering 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%, the second insulation layer 170 is difficult to stably adhere, and when it exceeds 30%, the exposed area of the first electrode pad 150 and the second electrode pad 160 becomes small, Can be increased. Therefore, the operating voltage can be increased.

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

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

The wavelength conversion layer 180 may include a phosphor or a quantum dot dispersed in the polymer resin. The kind of the phosphor is not particularly limited. In order to realize white light, a fluorescent material of at least one of YAG, TAG, silicate, Sulfide or Nitride may be included.

The extended portion 173a is fixed between the first and second electrode pads 150 and 160 and the circuit board 10 so that the second insulating layer 170 and the first and second electrode pads 150, 160 can be improved. 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 are in contact with the circuit board 10.

7A to 7F are flowcharts illustrating 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 may be formed to expose the first semiconductor layer 121 by etching the second semiconductor layer 123 and the active layer 122.

7B, after the protective layer 141 is formed on the light emitting structure 120 having the first groove H1 formed thereon, the first ohmic electrode 151 and the second ohmic electrode 131 are formed can do.

A reflective electrode layer 142 is formed on the second ohmic electrode 131. The reflective electrode layer 142 can be formed in the order of Ag / Ni / Ti using sputtering. At this time, 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, a first insulating layer 142 is formed on the entire surface. There is no limitation on the method of forming each layer. A mask pattern may be used or a photoresist may be used.

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

Referring to FIG. 7D, the second insulating layer 170 is formed on the side of the light emitting device in which the first electrode pad 150 and the second electrode pad 160 are disposed. The 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 structure, the problem that the reflective electrode layer is peeled off due to the current leaking phenomenon can be solved and the extraction efficiency of light emitted from the light emitting structure can be improved.

The light emitting device of the embodiment further includes optical members such as a light guide plate, a prism sheet, and a diffusion sheet, and can function as a backlight unit. Further, the light emitting element of the embodiment can be further applied to a display device, a lighting device, and a pointing device.

At this time, 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 forward, and the optical sheet includes a prism sheet or the like and is disposed in front of the light guide plate. The display panel is disposed in front of the optical sheet, and the image signal output circuit supplies an image signal to the display panel, and the color filter is disposed in front of the display panel.

The lighting device may include a light source module including a substrate and a light emitting device of the embodiment, a heat dissipation unit that dissipates heat of the light source module, and a power supply unit that processes or converts an electric signal provided from the outside and provides the light source module . Further, the lighting device may include a lamp, a head lamp, or a street lamp or the like.

It will be apparent to those skilled in the art that various changes, substitutions, and alterations can be made hereto without departing from the spirit and scope of the invention as defined in the appended claims. Will be apparent to those of ordinary skill in the art.

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 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 penetrating the first insulating layer and connected to the first semiconductor layer;
A second electrode pad penetrating 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.
The method according to claim 1,
And the second insulating layer reflects light emitted from the light emitting structure.
3. The method of claim 2,
Wherein the first insulating layer reflects light emitted from the light emitting structure.
The method according to claim 1,
And a substrate for supporting the light emitting structure,
And the second insulating layer includes a second region covering a side surface of the substrate.
The method according to claim 1,
And the second insulating layer includes a third region covering a side surface of the first electrode pad and the second electrode pad.
6. The method of claim 5,
And the third region includes an extension extending to a bottom surface of the first electrode pad and the second electrode pad.
The method according to claim 6,
Wherein the extending portion covers an area of a bottom surface of the first electrode pad and a surface of the second electrode pad is 5% to 30% of a total area of the bottom surface.
The method according to claim 1,
Wherein 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 a side surface of the first electrode pad and the second electrode pad,
Wherein the first region, the second region, and the third region have the same thickness.
9. The method of claim 8,
Wherein the second insulating layer includes a high refractive index layer and a low refractive index layer stacked alternately.
9. The method of claim 8,
Wherein the second insulating layer has a reflectance of 96% or more with respect to light having a wavelength of 450 nm.
A light emitting element; And
And a wavelength conversion layer for converting light emitted from the light emitting device into white light,
The light-
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 penetrating the first insulating layer and connected to the first semiconductor layer;
A second electrode pad penetrating 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.

Images