KR101679395B1 - Light emitting diode and method of fabricating the same - Google Patents

Light emitting diode and method of fabricating the same Download PDF

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KR101679395B1
KR101679395B1 KR1020160003271A KR20160003271A KR101679395B1 KR 101679395 B1 KR101679395 B1 KR 101679395B1 KR 1020160003271 A KR1020160003271 A KR 1020160003271A KR 20160003271 A KR20160003271 A KR 20160003271A KR 101679395 B1 KR101679395 B1 KR 101679395B1
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layer
semiconductor layer
type semiconductor
conductivity type
mesa
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KR1020160003271A
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KR20160009098A (en
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채종현
서대웅
노원영
장종민
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서울바이오시스 주식회사
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    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/36Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the electrodes
    • H01L33/40Materials therefor
    • H01L33/405Reflective materials
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/12Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a stress relaxation structure, e.g. buffer layer
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/02Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies
    • H01L33/14Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor bodies with a carrier transport control structure, e.g. highly-doped semiconductor layer or current-blocking structure
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L33/00Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48Semiconductor devices with at least one potential-jump barrier or surface barrier specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50Wavelength conversion elements
    • HELECTRICITY
    • H01BASIC ELECTRIC ELEMENTS
    • H01LSEMICONDUCTOR DEVICES; ELECTRIC SOLID STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H01L2924/00Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
    • H01L2924/10Details of semiconductor or other solid state devices to be connected
    • H01L2924/11Device type
    • H01L2924/12Passive devices, e.g. 2 terminal devices
    • H01L2924/1204Optical Diode
    • H01L2924/12041LED

Abstract

A light emitting diode according to embodiments of the present invention includes: a first conductive semiconductor layer; A mesa disposed on the first conductivity type semiconductor layer and including an active layer and a second conductivity type semiconductor layer; A reflective electrode positioned on the mesa and ohmic-contacting the second conductive semiconductor layer; A current diffusion layer positioned on the mesa and the reflective electrode and ohmic-contacting the first conductivity type semiconductor layer; A lower insulating layer disposed between the mesa and the reflective electrode and the current dispersion layer to insulate the current dispersion layer from the mesa and the reflective electrode; And an upper insulating layer covering the current spreading layer, the upper insulating layer having a first opening exposing the current spreading layer at an upper portion of the mesa region, wherein a part of the current spreading layer is formed near one edge of the first conductive semiconductor layer The ohmic contact is made to the first conductivity type semiconductor layer.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a light emitting diode (LED)

The present invention relates to a light emitting diode, and more particularly to a flip chip type light emitting diode having improved light emitting efficiency.

BACKGROUND ART GaN-based LEDs have been used in various applications such as color LED display devices, LED traffic signals, and white LEDs since gallium nitride (GaN) -based light emitting diodes have been developed.

Gallium nitride based light emitting diodes are generally formed by growing epitaxial layers on a substrate such as sapphire and include an N-type semiconductor layer, a P-type semiconductor layer, and an active layer interposed therebetween. On the other hand, an N-electrode pad is formed on the N-type semiconductor layer, and a P-electrode pad is formed on the P-type semiconductor layer. The light emitting diode is electrically connected to an external power source through the electrode pads. At this time, current flows from the P-electrode pad to the N-electrode pad through the semiconductor layers.

On the other hand, a flip-chip type light emitting diode is used to prevent light loss caused by the P-electrode pad and to increase heat dissipation efficiency, and various electrode structures for assisting current dispersion in a light emitting diode having a large area flip chip structure have been proposed See US 6,486,499). For example, a reflective electrode is formed on the P-type semiconductor layer, and the P-type semiconductor layer and the active layer are etched to form extensions for current dispersion on the exposed N-type semiconductor layer.

The reflective electrode formed on the P-type semiconductor layer reflects light generated in the active layer to improve the light extraction efficiency and also helps to distribute current in the P-type semiconductor layer. On the other hand, the extensions connected to the N-type semiconductor layer help to distribute the current in the N-type semiconductor layer, thereby generating light evenly in a wide active region. Particularly, in a large area light emitting diode of about 1 mm 2 or more, which is used for high output, current dispersion in the P-type semiconductor layer and current dispersion in the N-type semiconductor layer are required.

However, according to the prior art, since the linear extensions are used, the resistance of the extensions is so large that there is a limit in dispersing the current. Further, since the reflective electrode is located on the P-type semiconductor layer, light that is not reflected by the reflective electrode and is lost by the pads and extensions is significantly generated.

US Patent No. 6,486,499

A problem to be solved by the present invention is to provide a light emitting diode improved in current dispersion performance.

Another object of the present invention is to provide a light emitting diode capable of improving the light extraction efficiency by increasing the reflectance.

Another object of the present invention is to provide a method of manufacturing a light emitting diode that can improve the current dispersion performance while preventing the manufacturing process from being complicated.

According to an embodiment of the present invention, a light emitting diode includes: a first conductive semiconductor layer; A mesa disposed on the first conductivity type semiconductor layer and including an active layer and a second conductivity type semiconductor layer; A reflective electrode positioned on the mesa and ohmic-contacting the second conductive semiconductor layer; A current diffusion layer positioned on the mesa and the reflective electrode and ohmic-contacting the first conductivity type semiconductor layer; A lower insulating layer disposed between the mesa and the reflective electrode and the current dispersion layer to insulate the current dispersion layer from the mesa and the reflective electrode; And an upper insulating layer covering the current spreading layer, the upper insulating layer having a first opening exposing the current spreading layer at an upper portion of the mesa region, wherein a part of the current spreading layer is formed near one edge of the first conductive semiconductor layer The ohmic contact is made to the first conductivity type semiconductor layer.

According to another embodiment of the present invention, there is provided a light emitting diode comprising: a first conductive semiconductor layer; A plurality of mesas spaced apart from each other on the first conductive type semiconductor layer and each including an active layer and a second conductive type semiconductor layer; Reflective electrodes positioned on the plurality of mesas and ohmic-contacting the second conductivity type semiconductor layer, respectively; And a second conductive semiconductor layer over the first conductive semiconductor layer, the second conductive semiconductor layer having an opening for covering the mesa and the first conductive type semiconductor layer, the opening for exposing the reflective electrodes located in each of the mesa upper regions, And a current spreading layer insulated from the current spreading layer.

Since the current spreading layer covers a plurality of mesas and the first conductivity type semiconductor layer, the current dispersion performance is improved through the current dispersion layer.

The first conductive semiconductor layer is continuous. Furthermore, the plurality of mesas may have an elongated shape extending parallel to each other in one direction, and openings of the current dispersion layer may be biased toward the same end side of the plurality of mesas. Therefore, it is possible to easily form a pad connecting the reflective electrodes exposed in the openings of the current-spreading layer.

The current spreading layer may include a reflective metal such as Al. Thus, light reflection by the current-spreading layer can be obtained in addition to light reflection by the reflective electrodes, and thus light traveling through the plurality of mesa sidewalls and the first conductivity type semiconductor layer can be reflected.

The reflective electrodes may include a reflective metal layer and a barrier metal layer, respectively. Further, the barrier metal layer may cover the upper surface and side surfaces of the reflective metal layer. Thus, the reflective metal layer can be prevented from being exposed to the outside, and deterioration of the reflective metal layer can be prevented.

Wherein the light emitting diode comprises: an upper insulating layer covering at least a part of the current spreading layer, the upper insulating layer having openings for exposing the reflective electrodes; And a second pad disposed on the upper insulating layer and connected to the reflective electrodes exposed through the openings of the upper insulating layer. The display device may further include a first pad connected to the current dispersion layer . The first pad and the second pad may be formed in the same shape and size, so that flip chip bonding can be easily performed.

The light emitting diode may further include a lower insulating layer disposed between the plurality of mesas and the current dispersion layer to insulate the current dispersion layer from the plurality of mesas. The lower insulating layer may have openings located in the respective mesa upper regions and exposing the reflective electrodes.

Further, the openings of the current-spreading layer may have a wider width than the openings of the lower insulating layer so that the openings of the lower insulating layer are all exposed. That is, the sidewalls of the openings of the current spreading layer are located on the lower insulating layer. In addition, the light emitting diode may further include an upper insulating layer covering at least a part of the current spreading layer and having openings exposing the reflective electrodes. The upper insulating layer may cover sidewalls of the openings of the current spreading layer.

The lower insulating layer may be a reflective dielectric layer, such as a distributed Bragg reflector (DBR).

In some embodiments, the light emitting diode includes: an upper insulating layer covering the current dispersion layer, the upper insulating layer having openings exposing the reflective electrodes and an opening exposing the current dispersion layer; A first pad connected to the current spreading layer exposed through an opening of the upper insulating layer; And at least one second pad connected to the reflective electrodes exposed through the opening of the upper insulating layer.

The pad may further include a support portion surrounding the first pad and the second pad, and the support portion may be insulated from the first pad and the second pad. The support can support the epilayers, thus preventing cracking of the epilayers when thinning or separating the growth substrate.

The support portion may be formed of the same metal material as the first pad and the second pad. The first pad and the second pad may be formed one by one or a plurality of the first and second pads, respectively.

The support portion may include an outer frame surrounding the first pad and the second pad, and an inner connection portion located in a region between the first pad and the second pad.

In some embodiments, the pad of either the first pad or the second pad may surround another pad. One pad surrounding the other pad performs the function of the support together.

The light emitting diode may further include a wavelength conversion layer located on the first conductivity type semiconductor layer side facing the mesas, and the wavelength conversion layer may have a sheet shape or a lens shape. A transparent resin may be disposed on the wavelength conversion layer or between the wavelength conversion layer and the first conductivity type semiconductor layer.

Furthermore, a growth substrate may be positioned between the wavelength conversion layer and the first conductivity type semiconductor layer, but the growth substrate may be removed, and the wavelength conversion layer may be formed on the first conductivity type semiconductor layer.

A method of manufacturing a light emitting diode according to an embodiment of the present invention includes forming a first conductive semiconductor layer, an active layer, and a second conductive semiconductor layer on a substrate, patterning the second conductive semiconductor layer and the active layer, A plurality of mesas are formed on the first conductivity type semiconductor layer, reflection electrodes are formed on the plurality of mesas to make ohmic contact with each other, and the plurality of mesas and the first conductivity type semiconductor layer are covered, And forming openings for exposing the reflective electrodes, wherein the current spreading layer is ohmic-contacted with the first conductivity type semiconductor layer and is insulated from the plurality of mesas.

The method for fabricating a light emitting diode may further include forming a plurality of mesa and the first conductive type semiconductor layer on the first conductive type semiconductor layer before forming the current dispersion layer, And forming a lower insulating layer located above the mesa region and having openings exposing the reflective electrodes.

The method of manufacturing a light emitting diode may further include forming an upper insulating layer on the current spreading layer. Here, the upper insulating layer may have openings for exposing the reflective electrodes, and may cover the sidewalls of the openings of the current-spreading layer.

A second pad may be formed on the upper insulating layer and the second pad may be connected to the reflective electrodes exposed through the openings of the upper insulating layer. Furthermore, during formation of the second pad, a first pad connected to the current dispersion layer may be formed.

The upper insulating layer may have an opening exposing the current spreading layer, and the first pad may be connected to the current spreading layer through an opening exposing the current spreading layer.

In some embodiments, while forming the first pad and the second pad, a support portion surrounding the first pad and the second pad may be formed.

The forming of the first pad, the second pad, and the supporting portion may include forming a seed layer on the upper insulating layer, forming a mold defining the first pad region and the second pad region on the seed layer , Forming a plating layer on the seed layer inside and outside the region surrounded by the mold, removing the mold, and removing the seed layer located under the mold. Further, an insulating layer may be further formed to cover the support portion.

In some embodiments, any one of the first pad and the second pad may be formed to surround the other pad.

According to the embodiments of the present invention, a light emitting diode, particularly a flip chip type light emitting diode, having improved current dispersion performance can be provided. In addition, a light emitting diode having improved reflectance and improved light extraction efficiency can be provided. Furthermore, the growth substrate can be easily removed by forming the support together with the first pad and the second pad. Further, by simplifying the plurality of mesa structures, the manufacturing process of the light emitting diode can be simplified.

FIGS. 1 to 5 are views for explaining a method of manufacturing a light emitting diode according to an embodiment of the present invention, in which (a) is a plan view, and (b) is a cross-sectional view taken along the cutting line AA.
6 is a plan view for explaining a modified example of the mesa structure.
FIGS. 7 to 16 are views for explaining a method of fabricating a light emitting diode according to another embodiment of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view taken along a percutaneous line BB.
17 and 18 are sectional views for explaining various modifications of the light emitting diode of FIG.
19 is a plan view illustrating a method of fabricating a light emitting diode according to another embodiment of the present invention.
20 to 22 are plan views illustrating a method of fabricating a light emitting diode according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided by way of example so that those skilled in the art can fully understand the spirit of the present invention. Therefore, the present invention is not limited to the embodiments described below, but may be embodied in other forms. In the drawings, the width, length, thickness, etc. of components may be exaggerated for convenience. Like reference numerals designate like elements throughout the specification.

FIGS. 1 to 5 are views for explaining a method of manufacturing a light emitting diode according to an embodiment of the present invention, wherein (a) is a plan view and (b) is a cross-sectional view taken along the cutting line A-A.

1, a first conductivity type semiconductor layer 23 is formed on a substrate 21 and a plurality of mesas M spaced apart from each other on the first conductivity type semiconductor layer 23 . The plurality of mesas M each include an active layer 25 and a second conductivity type semiconductor layer 27. The active layer 25 is located between the first conductivity type semiconductor layer 23 and the second conductivity type semiconductor layer 27. [ On the other hand, the reflective electrodes 30 are positioned on the plurality of mesas M, respectively.

The plurality of mesas M may be formed by depositing an epitaxial layer including a first conductive semiconductor layer 23, an active layer 25 and a second conductive semiconductor layer 27 on a substrate 21 by a metal organic chemical vapor deposition And then patterning the second conductivity type semiconductor layer 27 and the active layer 25 so that the first conductivity type semiconductor layer 23 is exposed. The sides of the plurality of mesas M may be formed obliquely by using a technique such as photoresist reflow. The inclined profile of the mesa (M) side improves the extraction efficiency of the light generated in the active layer 25.

The plurality of mesas M may have an elongated shape extending parallel to each other in one direction as shown. This shape simplifies the formation of a plurality of mesas M of the same shape in a plurality of chip areas on the substrate 21. [

The reflective electrodes 30 may be formed on each of the mesas M after the plurality of mesas M are formed. However, the present invention is not limited thereto, and the second conductivity type semiconductor layer 27 may be grown It may be formed on the second conductive type semiconductor layer 27 before forming the mesas M. [ The reflective electrode 30 covers most of the upper surface of the mesa M and has substantially the same shape as the planar shape of the mesa M. [

The reflective electrodes 30 include a reflective layer 28 and may further comprise a barrier layer 29. [ The barrier layer 29 may cover the top and side surfaces of the reflective layer 28. For example, the barrier layer 29 may be formed to cover the upper surface and the side surface of the reflective layer 28 by forming a pattern of the reflective layer 28 and forming a barrier layer 29 thereon. For example, the reflective layer 28 may be formed by depositing and patterning Ag, Ag alloy, Ni / Ag, NiZn / Ag, and TiO / Ag layers. The barrier layer 29 may be formed of Ni, Cr, Ti, Pt, Rd, Ru, W, Mo, TiW or a composite layer thereof to prevent diffusion or contamination of the metal material of the reflection layer.

After the plurality of mesas M are formed, the edges of the first conductive type semiconductor layer 23 may also be etched. Thus, the upper surface of the substrate 21 can be exposed. The side surfaces of the first conductivity type semiconductor layer 23 may also be inclined.

The plurality of mesas M may be formed to be confined within the upper region of the first conductivity type semiconductor layer 23 as shown in FIG. That is, a plurality of mesas M may be located on the upper region of the first conductivity type semiconductor layer 23 in an island shape. Alternatively, as shown in FIG. 6, the mesa M extending in one direction may be formed to reach the upper edge of the first conductive type semiconductor layer 23. That is, the one side edge of the lower surface of the plurality of mesas M coincides with the edge of one side of the first conductivity type semiconductor layer 23. Accordingly, the upper surface of the first conductivity type semiconductor layer 23 is partitioned by the plurality of mesas M.

Referring to FIG. 2, a lower insulating layer 31 covering the plurality of mesas M and the first conductivity type semiconductor layer 23 is formed. The lower insulating layer 31 has openings 31a and 31b for allowing electrical connection to the first conductivity type semiconductor layer 23 and the second conductivity type semiconductor layer 27 in a specific region. For example, the lower insulating layer 31 may have openings 31a for exposing the first conductivity type semiconductor layer 23 and openings 31b for exposing the reflective electrodes 30.

The openings 31a may be located near the region between the mesas M and the edge of the substrate 21 and may have an elongated shape extending along the mesas M. [ On the other hand, the openings 31b are located on the upper portion of the mesa M and are biased to the same end side of the mesa.

The lower insulating layer 31 may be formed of an oxide film such as SiO 2 , a nitride film such as SiN x, or an insulating film of SiON or MgF 2 using a technique such as chemical vapor deposition (CVD). The lower insulating layer 31 may be formed of a single layer, but is not limited thereto and may be formed of multiple layers. Further, the lower insulating layer 31 may be formed of a distributed Bragg reflector (DBR) in which a low refractive index material layer and a high refractive index material layer are alternately laminated. For example, an insulating reflection layer having a high reflectance can be formed by laminating layers such as SiO 2 / TiO 2 and SiO 2 / Nb 2 O 5 .

Referring to FIG. 3, a current spreading layer 33 is formed on the lower insulating layer 31. The current spreading layer 33 covers the plurality of mesas M and the first conductivity type semiconductor layer 23. In addition, the current spreading layer 33 has openings 33a located in the respective upper portions of the mesa M and exposing the reflective electrodes. The current spreading layer 33 may be in ohmic contact with the first conductive semiconductor layer 23 through the openings 31a of the lower insulating layer 31. [ The current spreading layer 33 is insulated from the plurality of mesas M and the reflective electrodes 30 by the lower insulating layer 31.

The openings 33a of the current spreading layer 33 are formed to have a larger area than the openings 31b of the lower insulating layer 31 so as to prevent the current spreading layer 33 from being connected to the reflective electrodes 30. [ Respectively. Therefore, the side walls of the openings 33a are located on the lower insulating layer 31. [

The current spreading layer 33 is formed on almost the entire region of the substrate 31 except for the openings 33a. Therefore, the current can be easily dispersed through the current dispersion layer 33. The current spreading layer 33 may include a highly reflective metal layer such as an Al layer and the highly reflective metal layer may be formed on an adhesive layer such as Ti, Cr, or Ni. Further, a protective layer of a single layer or a multi-layer structure such as Ni, Cr, Au or the like may be formed on the highly reflective metal layer. The current spreading layer 33 may have a multilayer structure of Ti / Al / Ti / Ni / Au, for example.

Referring to FIG. 4, an upper insulating layer 35 is formed on the current spreading layer 33. The upper insulating layer 35 has openings 35b for exposing the reflective electrodes 30 together with openings 35a for exposing the current spreading layer 33. [ The opening 35a may have an elongated shape in a direction perpendicular to the longitudinal direction of the mesa M and has a relatively large area as compared with the openings 35b. The openings 35b expose the exposed reflective electrodes 30 through the openings 33a of the current spreading layer 33 and the openings 31b of the lower insulating layer 31. [ The openings 35b may have a smaller area than the openings 33a of the current spreading layer 33 and may have a larger area than the openings 31b of the lower insulating layer 31. [ Accordingly, the sidewalls of the openings 33a of the current-spreading layer 33 may be covered with the upper insulating layer 35.

The upper insulating layer 35 may be formed using an oxide insulating layer, a nitride insulating layer, a mixed layer or a cross layer of these insulating layers, or a polymer such as polyimide, Teflon, or parylene.

Referring to FIG. 5, a first pad 37a and a second pad 37b are formed on the upper insulating layer 35. Referring to FIG. The first pad 37a is connected to the current spreading layer 33 through the opening 35a of the upper insulating layer 35 and the second pad 37b is connected to the openings 35b of the upper insulating layer 35 To the reflective electrodes 30. The first pad 37a and the second pad 37b may be used as pads for connecting SMTs or connecting bumps for mounting the light emitting diode on a submount, a package, a printed circuit board, or the like.

The first and second pads 37a and 37b may be formed together in the same process and may be formed using, for example, a photo and etch technique or a lift-off technique. The first and second pads 37a and 37b may include, for example, an adhesive layer of Ti, Cr, Ni, or the like and a high-conductivity layer of metal such as Al, Cu, Ag, or Au.

Thereafter, the substrate 21 is divided into individual LED chip units to complete the light emitting diode. The substrate 21 may be removed from the light emitting diode chip before or after being divided into individual light emitting diode chip units.

Hereinafter, a structure of a light emitting diode according to an embodiment of the present invention will be described in detail with reference to FIG.

The light emitting diode includes a first conductive semiconductor layer 23, a mesa M, reflective electrodes 30 and a current dispersion layer 33. The light emitting diode includes a substrate 21, a lower insulating layer 31, An upper insulating layer 35 and first and second pads 37a and 37b.

The substrate 21 may be a growth substrate for growing gallium nitride epilayers, for example, sapphire, silicon carbide, silicon, or a gallium nitride substrate.

The first conductivity type semiconductor layer 23 is continuous and a plurality of mesas M are disposed on the first conductivity type semiconductor layer 23 so as to be spaced apart from each other. The mesas M include the active layer 25 and the second conductivity type semiconductor layer 27 as described with reference to FIG. 1 and have an elongated shape extending toward one side. Here, the mesas M are stacked layers of gallium nitride compound semiconductors. The mesa M may be located within the upper region of the first conductivity type semiconductor layer 23 as shown in FIG. 6, the mesa M may extend to a top edge of the first conductivity type semiconductor layer 23 along one direction, so that the first conductivity type semiconductor layer 23 can be divided into a plurality of regions. Accordingly, concentration of current in the vicinity of the edge of the mesa M can be mitigated to further enhance the current dispersion performance.

Each of the reflective electrodes 30 is located on the plurality of mesas M and ohmically contacts the second conductive type semiconductor layer 27. The reflective electrodes 300 may include a reflective layer 28 and a barrier layer 29 as described with reference to Figure 1 and a barrier layer 29 may cover the top and sides of the reflective layer 28.

The current spreading layer 33 covers the plurality of mesas M and the first conductivity type semiconductor layer 23. The current spreading layer 33 has openings 33a that are located in the respective upper portions of the mesa M and expose the reflective electrodes 30. [ The current spreading layer 33 is also in ohmic contact with the first conductivity type semiconductor layer 23 and is insulated from the plurality of mesas M. [ The current spreading layer 33 may include a reflective metal such as Al.

The current spreading layer 33 may be insulated from the plurality of mesas M by a lower insulating layer 31. For example, the lower insulating layer 31 may be positioned between the plurality of mesas M and the current spreading layer 33 to isolate the current spreading layer 33 from the plurality of mesas M . The lower insulating layer 31 may have openings 31b that are located in the respective upper portions of the mesa M and expose the reflective electrodes 30. The lower insulating layer 31 may have openings 31b, (Not shown). The current spreading layer 33 may be connected to the first conductivity type semiconductor layer 23 through the openings 31a. The openings 31b of the lower insulating layer 31 have a smaller area than the openings 33a of the current spreading layer 33 and are all exposed by the openings 33a.

The upper insulating layer 35 covers at least a part of the current-spreading layer 33. The upper insulating layer 35 has openings 35b for exposing the reflective electrodes 30. Furthermore, the upper insulating layer 35 may have an opening 35a for exposing the current-spreading layer 33. [ The upper insulating layer 35 may cover the sidewalls of the openings 33a of the current spreading layer 33.

The first pad 37a may be located on the current spreading layer 33 and may be connected to the current spreading layer 33 through the opening 35a of the upper insulating layer 35, for example. The second pad 37b is connected to the reflective electrodes 30 exposed through the openings 35b.

According to the present invention, the current-spreading layer 33 covers almost the entire region of the first conductivity type semiconductor layer 23 between the mesas M and the mesas M. [ Therefore, the current can be easily dispersed through the current dispersion layer 33. [

The current dispersion layer 23 includes a reflective metal layer such as Al or the lower insulating layer is formed of an insulating reflection layer so that the light that is not reflected by the reflective electrodes 30 is separated from the current dispersion layer 23 or the lower insulating layer 23. [ Layer 31, so that the light extraction efficiency can be improved.

An embodiment of the present invention has been described in detail with reference to Figs. 1 to 5, and it has been described that the substrate 21 can be finally removed. However, since the first pad 37a and the second pad 37b are separated from each other and there is no supporting member for supporting the epilayers, when the substrate 21 is thinned or separated, the problem that the epilayers are fragile . Conventionally, a technique of attaching a secondary substrate to an epi layer and then separating the growth substrate using a chemical etching technique or a laser lift-off technique is well known. However, since the secondary substrate must be attached separately, the manufacturing cost is increased. Therefore, there is also a demand for a technique capable of forming the first and second pads while replacing the secondary substrate at the wafer level in order to prevent cracking of the epilayers generated when the substrate 21 is thinned or separated.

FIGS. 7 to 16 are views for explaining a method of manufacturing a light emitting diode according to another embodiment of the present invention, wherein (a) is a plan view and (b) is a sectional view taken along a perforated line B-B.

Referring to FIG. 7, a first conductive semiconductor layer 21, a plurality of mesas M, and reflective electrodes 30 are formed on a substrate 21, as described with reference to FIG. The first conductive semiconductor layer 21, the plurality of mesas M, and the reflective electrodes 30 are the same as those described with reference to FIG. 1, and a detailed description thereof will be omitted. 7A, the mesa M extending in one direction is formed so as to reach the upper edge of the first conductivity type semiconductor layer 23 as shown in Fig. 6, Respectively. However, the plurality of mesas M may be formed to be confined within the upper region of the first conductivity type semiconductor layer 23 as shown in FIG. That is, the plurality of mesas M may be located in an island shape on the upper region of the first conductivity type semiconductor layer 23.

Referring to FIG. 8, a lower insulating layer 31 is formed to cover the plurality of mesas M and the first conductivity type semiconductor layer 23, and the lower insulating layer 31 Has openings 31a and 31b for allowing electrical connection to the first conductivity type semiconductor layer 23 and the second conductivity type semiconductor layer 27. [ However, in the present embodiment, the openings 31b may be formed in a triangular shape instead of being positioned at the same end side. Respectively. Furthermore, a plurality of the openings 31b may be formed on each of the mesas M. [

3, a current spreading layer 33 is formed on the lower insulating layer 31 and the current spreading layer 33 is formed on the lower surface of the plurality of mesas M, And the first conductivity type semiconductor layer (23). 3, the current dispersion layer 33 is insulated from the plurality of mesas M and the reflective electrodes 30 by the lower insulating layer 31, and each of the mesas M ) Openings (33a) located in the upper region and exposing the reflective electrodes.

Referring to FIG. 10, an upper insulating layer 35 is formed on the current spreading layer 33. The upper insulating layer 35 has openings 35b for exposing the reflective electrodes 30 together with openings 35a for exposing the current spreading layer 33. [ The opening 35a may have substantially the same area as the openings 35b. The openings 35b expose the exposed reflective electrodes 30 through the openings 33a of the current spreading layer 33 and the openings 31b of the lower insulating layer 31. [ The openings 35b may have a smaller area than the openings 33a of the current spreading layer 33 and may have a larger area than the openings 31b of the lower insulating layer 31. [ Accordingly, the sidewalls of the openings 33a of the current-spreading layer 33 may be covered with the upper insulating layer 35.

The upper insulating layer 35 may be formed using an oxide insulating layer, a nitride insulating layer, or a polymer such as polyimide, Teflon, or parylene.

Referring to FIG. 11, a seed layer 41 is formed on the upper insulating layer 35. The seed layer 41 is a seed layer for plating, and may be formed of Au or Cu. The seed layer 41 covers the upper insulating layer 35 and covers the inside of the openings 35a and 35b.

Referring to FIG. 12, a mold 43 is formed on the seed layer 41. The mold 43 may be formed to a thickness of, for example, 20um or more, and may be formed using a photoresist, SU8, polyimide or the like.

As shown in the figure, the mold 43 may be formed in a ring shape such as a triangular ring, a rectangular ring, or a circular ring so as to surround the openings 35a and 35b.

The first pad region located above the opening portion 35a and the second pad regions located above the opening portions 35b are separated from the external region by the mold 43. [

Referring to FIG. 13, a plating layer is formed on the first pad region and the second pad regions surrounded by the mold 43, and on the outer region of the regions surrounded by the mold 43. The plating layer may be formed of Ni, Cu, or the like on the seed layer 41. 45a and 45b, the first pad 47a and the second pad 47b by planarizing the plating layer and the mold 43 using a planarization process such as lapping or CMP, .

The first pad 47a is connected to the current dispersion layer 33 and the second pad 47b is connected to the reflective electrode 30. [

The supporting portion 45 includes an outer frame 45a surrounding the entirety of the first pad 47a and the second pad 47b and an inner frame 45b located between the pads 47a and 47b And may have a connecting portion 45b.

Referring to FIG. 14, the mold 43 and the seed layer 41 located under the mold 43 are removed. The mold 43 may be removed using ashing or wet etching techniques, and the seed layer 41 may be removed using a wet etch technique. Accordingly, the support portion 45 is insulated from the first and second pads 47a and 47b.

A bonding layer (not shown) such as an Au or AuSn layer for eutectic bonding may be formed on the first pad 47a and the second pad 47b before the mold 43 is removed.

An insulating layer 49 may further be formed to prevent the short circuit between the supporting portion 45 and the first and second pads 47a and 47b. The insulating layer 49 covers the surface of the supporting part 45 to insulate the supporting part 45 from the first and second pads 47a and 47b. The insulating layer 49 can prevent the first pad 47a and the second pad 47b from being short-circuited in the subsequent bonding process. The insulating layer 49 may be formed of an oxide-based or nitride-based insulating layer or polyimide, Teflon, paraphenylene, paralin, etc. Openings for exposing the first pad 47a and the second pad 47b (49a, 49b) can be formed by photolithography, dry etching, or the like.

Referring to FIG. 15, after the rigidity is secured by the supporting portion 45, the substrate 21 may be thinned or separated from the first conductivity type semiconductor layer 23. For example, the substrate 21 may be partially or completely removed using lapping and / or CMP techniques, or may be separated using chemical lift-off or laser lift-off techniques.

When the first conductivity type semiconductor layer 23 is exposed, the exposed surface of the first conductivity type semiconductor layer 23 is exposed to a rough surface R using a photo-enhanced chemical etch, Can be formed.

Referring to FIG. 16, the wavelength conversion layer 51 may be formed on the first conductivity type semiconductor layer 23 side. The wavelength conversion layer 51 may contain a phosphor to change the wavelength of light emitted from the active layer 25. The wavelength conversion layer 51 may be in the form of a sheet having a flat surface and a lens-shaped transparent resin 53 may be formed on the wavelength conversion layer 51. Alternatively, as shown in Fig. 17, the wavelength conversion layer 55 may be formed in a lens shape. As shown in Fig. 18, on the first conductivity type semiconductor layer 23, a lens- (57) may be formed first, and the wavelength conversion layer (59) may be formed thereon.

Although it has been described that the wavelength conversion layers 51, 55, and 59 and the transparent resins 53 and 37 are formed on the first conductivity type semiconductor layer 23, if the substrate 21 is left unremoved , These wavelength conversion layers and the transparent resin can be formed on the substrate 21. [

According to the present embodiment, by forming the supporting portions 45 together with the first pads 47a and the second pads 47b, cracks can be prevented from occurring in the epilayers when the substrate 21 is thinned or separated have.

Further, the light emitting diode manufactured according to this embodiment is provided as a wafer level package that does not require a separate packaging process.

19 is a plan view illustrating a method of fabricating a light emitting diode according to another embodiment of the present invention.

19, in the above embodiments, one first pad 47a is formed and one first pad 47b is connected to each of the reflective electrodes 30, Two or more first pads 47a may be formed and connected to the current dispersion layer 33 and two or more second pads 47b may be connected to each of the reflection electrodes 30. In this embodiment, have.

The upper insulating layer 35 corresponding to the first pads 47a may have a plurality of openings for exposing the current dispersion layer 33 and may have a plurality of openings for exposing the reflective electrodes 30 on the respective mesa- .

The inner connecting portions 45b of the supporting portion 45 can be formed more by separating the first pad 47a and the second pads 47b into a plurality of portions and the rigidity of the supporting portion 45 can be improved .

20 to 23 are plan views illustrating a method of fabricating a light emitting diode according to another embodiment of the present invention.

Referring to FIG. 20, a seed layer 41 is formed through the same steps as those described with reference to FIGS. 7 to 11. 12, the mold 43 is formed. In the present embodiment, only the mold 43 surrounding the opening 35a for exposing the current-spreading layer 33 is formed, The mold surrounding the grooves 35b is omitted. That is, in the present embodiment, the mold 43 separates the region around the opening 35a, that is, the first pad region from another external region, and the second pad region is not separately separated.

21, a plated layer is formed and the mold 43 and the plated layer are planarized to form a first pad 47a in an area surrounded by the mold 43, A second pad 67b is formed on the outer side of the second pad 43. [ That is, in the present embodiment, the second pad 67b surrounds the first pad 47a, and has a function as a pad connected to the reflective electrodes 30 and a function as a support.

Referring to FIG. 22, the mold 43 and the seed layer 41 under the mold 43 are removed to remove the first pad 47a from the second pad 67b electrically And an insulating layer 69 is formed to prevent a short circuit between the first pad 47a and the second pad 67b. The insulating layer 69 may have an opening 69a exposing the first pad 47a and an opening 69b exposing the bonding area of the second pad 67b.

According to the present embodiment, the second pad 67b is formed so as to function as a support portion, thereby further increasing the formation area of the support portion, thereby improving the rigidity.

In the present embodiment, the second pad 67b is formed to surround the first pad 47a and functions as a support. Conversely, the first pad 47a is formed to surround the second pad 67b And may have the function of a supporting portion. In this case, in FIG. 20, the mold 43 surrounding the opening 35a for exposing the current-spreading layer 33 is omitted, and a mold surrounding the openings 35b will be formed.

Claims (19)

  1. A first conductive semiconductor layer;
    A mesa disposed on the first conductivity type semiconductor layer and including an active layer and a second conductivity type semiconductor layer;
    A reflective electrode positioned on the mesa and ohmic-contacting the second conductive semiconductor layer;
    A current diffusion layer positioned on the mesa and the reflective electrode and ohmic-contacting the first conductivity type semiconductor layer;
    A lower insulating layer disposed between the mesa and the reflective electrode and the current dispersion layer to insulate the current dispersion layer from the mesa and the reflective electrode;
    An upper insulating layer covering the current spreading layer, the upper insulating layer having a first opening exposing the current spreading layer at an upper portion of the mesa region;
    A first pad electrically connecting to the current spreading layer; And
    And a second pad electrically connected to the reflective electrode,
    A part of the current spreading layer is in ohmic contact with the first conductivity type semiconductor layer in the vicinity of one edge of the first conductivity type semiconductor layer,
    The first pad is connected to the current dispersion layer through a first opening of the upper insulating layer,
    Wherein the lower insulating layer has an opening for exposing the reflective electrode,
    Wherein the current-spreading layer has an opening for exposing an opening of the lower insulating layer on the reflective electrode,
    Wherein the upper insulating layer has a second opening narrower than an opening region of the current spreading layer,
    And the second pad electrically connects to the reflective electrode through the second opening of the upper insulating layer, the opening of the current dispersion layer, and the opening of the lower insulating layer.
  2. The method according to claim 1,
    A portion of the current spreading layer that makes an ohmic contact with the first conductivity type semiconductor layer in the vicinity of one edge of the first conductivity type semiconductor layer is spaced apart from one side edge of the mesa and the first conductivity type semiconductor layer, A light emitting diode that makes an ohmic contact with a semiconductor layer.
  3. The method of claim 2,
    A part of the current spreading layer which makes an ohmic contact with the first conductivity type semiconductor layer near one edge of the first conductivity type semiconductor layer is formed in a long shape along one side edge of the first conductivity type semiconductor layer, A light emitting diode that makes an ohmic contact with a semiconductor layer.
  4. The method of claim 2,
    Wherein the current-spreading layer further makes an ohmic contact with the first conductivity-type semiconductor layer in the vicinity of the other edge opposite to one side edge of the first conductivity type semiconductor layer.
  5. The method of claim 4,
    Wherein the current spreading layer has ohmic contact with the first conductivity type semiconductor layer in the vicinity of the one side edge and the other side edge and in addition to the first conductivity type semiconductor layer in the plurality of regions near the one side edge and the other side edge, A light emitting diode that makes an ohmic contact with a semiconductor layer.
  6. The method of claim 2,
    Wherein an area between a part of the current spreading layer and one side edge of the first conductivity type semiconductor layer is covered with an insulating layer.
  7. The method according to claim 1,
    Wherein the mesa is confined within an upper region of the first conductive semiconductor layer.
  8. The method according to claim 1,
    Wherein the current dispersion layer comprises a reflective metal.
  9. delete
  10. delete
  11. The method according to claim 1,
    And the second pad has a larger area than the second opening of the upper insulating layer and covers the second opening.
  12. The method according to claim 1,
    Wherein an opening of the current spreading layer has a larger width than an opening of the lower insulating layer that exposes the reflective electrode.
  13. The method according to claim 1,
    Wherein the opening of the current spreading layer is biased to one side edge of the mesa.
  14. The method according to claim 1,
    Wherein the reflective electrodes each include a reflective metal layer and a barrier metal layer, wherein the barrier metal layer covers the top and side surfaces of the reflective metal layer.
  15. The method according to claim 1,
    And a wavelength conversion layer located on the side of the first conductivity type semiconductor layer opposite to the mesa.
  16. 16. The method of claim 15,
    Wherein the wavelength conversion layer has a flat surface.
  17. 18. The method of claim 16,
    And a substrate between the first conductivity type semiconductor layer and the wavelength conversion layer.
  18. 18. The method of claim 17,
    Wherein the substrate is a growth substrate on which the first conductivity type semiconductor layer is grown.
  19. The method according to claim 1,
    Wherein the lower insulating layer has a plurality of openings exposing the first conductive type semiconductor layer,
    And the current spreading layer is electrically connected to the first conductivity type semiconductor layer at a plurality of positions through openings of the lower insulating layer.
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Citations (3)

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Publication number Priority date Publication date Assignee Title
JP2008160046A (en) * 2006-12-21 2008-07-10 Lg Electronics Inc Light emitting element package and its manufacturing method
US20090283787A1 (en) * 2007-11-14 2009-11-19 Matthew Donofrio Semiconductor light emitting diodes having reflective structures and methods of fabricating same
JP2010087515A (en) 2008-09-30 2010-04-15 Seoul Opto Devices Co Ltd Light emitting device and method of manufacturing the same

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2008160046A (en) * 2006-12-21 2008-07-10 Lg Electronics Inc Light emitting element package and its manufacturing method
US20090283787A1 (en) * 2007-11-14 2009-11-19 Matthew Donofrio Semiconductor light emitting diodes having reflective structures and methods of fabricating same
JP2010087515A (en) 2008-09-30 2010-04-15 Seoul Opto Devices Co Ltd Light emitting device and method of manufacturing the same

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