KR101929678B1 - Filp type white GaN based light emitting diode with AlGaInP yellow light compensation region and a manufacturing method thereof - Google Patents

Abstract

The present invention relates to a white light emitting diode and a manufacturing method thereof and, more specifically, to a flip type white GaN light emitting diode of which a manufacturing process is simple and a manufacturing method thereof. According to the present invention, the flip type white light emitting diode comprises: a sapphire substrate; an AlGaInP-based light compensation unit formed on an upper part of the sapphire substrate; a GaN light emitting unit formed on a lower part of the sapphire substrate; and an etching unit exposing an upper limitation layer formed on one side of the GaN light emitting unit, wherein the GaN light emitting unit outputs a blue light by applied power, the AlGaInP-based light compensation unit outputs a yellow light by the outputted blue light from the GaN light emitting unit, and the diode outputs a white light by the blue light and the yellow light.

Description

FIELD OF THE INVENTION The present invention relates to a flip-type white gallium nitride light-emitting diode having an aluminum gallium indium phosphide yellow light compensation part and a method of manufacturing the white light-

The present invention relates to a white light emitting diode and a method of manufacturing the same, and more particularly, to a flip type white gallium nitride light emitting diode and a method of manufacturing the same.

In the GaN-based white light emitting diode, blue light having a wavelength of 450 nm is emitted from a GaN light emitting portion epitaxially grown on a sapphire (Al ₂ O ₃ ) substrate, and the emitted blue light is converted into a white light source by yellow phosphor fluorescence .

The GaN light emitting portion emitting a 450 nm blue wavelength is composed of an n-GaN confinement layer, a U-GaN / InGaN active layer, and a p-GaN confining layer. In addition, a U-GaN buffer layer is formed between the sapphire substrate and the GaN light emitting portion so that the GaN light emitting portion can be epitaxially grown on the sapphire substrate.

Since the efficiency of the latter type electrode is significantly lowered due to the nonconductive property of the U-GaN buffer layer, the efficiency of the PDL is lowered. Therefore, a flip type (a flip type) in which the p- ) Structure is mainly used, and a yellow phosphor (fluorescent material) is applied on the top of the sapphire substrate.

However, such a flip-type GaN-based white light emitting diode has a problem that not only the production yield is low due to the additional processing steps but also the fluorescent material applied non-uniformly on the sapphire causes a light attenuation phenomenon.

In order to solve this problem, a technique of fabricating a white GaN light emitting diode by bonding an AlGaInP light emitting diode and a GaN blue light emitting diode to each other has been developed.

[0004] Samsung Electronics Co., Ltd., Korean Patent Application No. 10-2006-0124510, which is a "white light emitting device" invented by Kim Minho et al., Discloses a conductive submount substrate; A first light emitting portion joined by a metal layer on a submount substrate and sequentially stacking a p-type nitride semiconductor layer, a first active layer, an n-type nitride semiconductor layer, and a conductive substrate from below; A second light emitting portion formed on one region of the upper surface of the conductive substrate and comprising a p-type AlGaInP semiconductor layer, a second active layer, and an n-type AlGaInP semiconductor layer sequentially laminated from below; And a p-side and an n-side electrode formed on the lower surface of the conductive sub-mount substrate and on the upper surface of the n-type AlGaInP-based semiconductor layer, respectively.

1, the white light emitting device 130 includes a submount substrate 131, first and second light emitting devices 130 and 140, and first and second light emitting devices 130 and 140, which emit different wavelength lights. 2 light emitting units 120 and 140. The submount substrate 131 may include a p-side lead electrode 132a and an n-side lead electrode 132b on an upper surface thereof. The submount substrate 131 may be a silicon substrate or a metal substrate, (Not shown) is formed on an ordinary silicon substrate and then the lead electrodes 132a and 132b, which are electrically separated from each other, are deposited. The first light emitting portion 120 is disposed such that the p-type nitride semiconductor layer 126, the two nitride active layers 124 and 125, the n-type nitride semiconductor layer 122, and the insulating substrate 121 are sequentially positioned from below And a part of the n-type nitride semiconductor layer 122 is exposed. The first metal layer 128 may be formed on the p-type nitride semiconductor layer 126, and the first metal layer 128 may include a highly reflective metal. The highly reflective metal may be a metal selected from the group consisting of aluminum (Al), silver (Ag), rhodium (Rh), ruthenium (Ru), platinum (Pt), palladium (Pd) and alloys thereof. A separate ohmic contact layer (not shown) may be added between the first metal layer 128 and the p-type nitride semiconductor layer 126. Preferably, a transparent oxide layer such as Cu-doped In2O3 may be used. The first light emitting portion 120 is flip-chip bonded onto the submount substrate 131. That is, the p-type nitride semiconductor layer 126 and the exposed n-type nitride semiconductor layer 122 are bonded to the p-side and n-side lead electrodes 132a and 132b by the bump solder S, respectively.

A second metal layer 138 is formed on an upper surface of the insulating substrate 121 on which the second light emitting portion 140 is to be formed. Since the substrate 121 of the first light emitting unit 120 has electrical insulation, the second metal layer 138 may be directly formed on the substrate 121. The area of the second metal layer 138 is smaller than the remaining area of the substrate 121 in order to ensure a sufficient light extraction area of the first light emitting part 120. The second light emitting portion 140 is formed on a part of the upper surface of the second metal layer 128 and includes a p-type AlGaInP semiconductor layer 146, an AlGaInP active layer 145, and an n-type AlGaInP semiconductor layer (143) are sequentially positioned. In the upper surface region of the insulating substrate 121 where the second light emitting portion 140 is not formed, the light extraction efficiency of the first light emitting portion 120 is further improved by forming the concave and convex pattern 121a.

In this structure, the first light emitting unit 120 and the second light emitting unit 140 are independently driven, and the first light emitting unit 120 is connected to each lead (not shown) provided on the upper surface of the submount substrate 131, The second light emitting portion 140 is driven by the electrodes 132a and 132b and the p-side electrode 148 and the n-type AlGaInP-based semiconductor layer 142, which are formed in one region of the second metal layer 138, An n-side electrode 149 formed on the upper surface is provided. Of course, it may be driven simultaneously to realize white light.

However, this method has a problem in that the process of selectively forming the second light emitting portion in a partial region of the upper portion of the nonconductive sapphire substrate is complicated and separate electrodes are required to drive the second light emitting portion.

Accordingly, there is a continuing need for a new flip-type GaN-based white light emitting diode manufacturing method which is easier to manufacture.

A problem to be solved by the present invention is to provide a method of manufacturing a flip type white GaN light emitting diode having a simple manufacturing process.

Another object of the present invention is to provide a new flip type white GaN light emitting diode.

In order to solve the above problems,

Sapphire substrate;

An AlGaInP-based optical compensator formed on the sapphire;

A GaN light emitting portion formed on a lower portion of the sapphire substrate;

And an etch portion exposing an upper confinement layer formed on one side of the GaN light emitting portion,

Here, the GaN light emitting portion emits blue light by a power source applied through the lower portion of the GaN light emitting portion and the etching portion, and the AlGaInP light compensating portion excites the blue light emitted from the GaN light emitting portion to emit the yellow light , And the diode emits white light by the blue light and the yellow light.

The present invention, in another aspect,

Providing a sapphire substrate;

Forming a GaN light emitting portion for emitting blue light in a lower portion of the sapphire substrate;

Etching a part of the GaN light emitting portion so that the upper limiting layer is exposed in the GaN light emitting portion; And

And forming an AlGaInP-based optical compensator on the sapphire substrate,

Here, the GaN light emitting portion emits blue light by a power source applied through the lower portion of the GaN light emitting portion and the etching portion, and the AlGaInP light compensating portion emits yellow light by the blue light emitted from the GaN light emitting portion. The diode emits blue light And white light is emitted by the yellow light. The present invention also provides a method of manufacturing a flip-type white light emitting diode.

In the present invention, the upper part refers to the direction in which the AlGaInP light compensating part is positioned based on the sapphire substrate, and the lower part refers to the direction in which the GaN-based light emitting part is positioned based on the sapphire substrate.

In the present invention, the GaN light emitting portion may include a GaN upper confinement layer, a GaN active layer grown in the GaN upper confinement layer; And a GaN lower confinement layer grown in the GaN active layer.

In the present invention, the GaN light emitting portion can emit blue light having a peak wavelength of 440 to 460 mu m, preferably 450 mu m.

In the practice of the present invention, the GaN upper confinement layer constituting the GaN light emitting portion may be an n-GaN clad, and the GaN active layer may be an active layer formed by alternately growing U-InGaN / GaN, -GaN clad.

In the practice of the present invention, a U-GaN buffer layer having a thickness of preferably 2 to 5 탆, more preferably about 3 탆 may be provided on the lower surface of the sapphire substrate so that the GaN upper confinement layer can be stably grown. A transparent electrode layer may be formed on the lower surface of the lower confinement layer to increase the conductivity.

In the present invention, the AlGaInP-based optical compensator may be composed of an AlGaInP lower limiting layer, an AlGaInP-based active layer grown in the lower limiting layer, and an upper limiting layer grown in the AlGaInP-based active layer.

In the present invention, the AlGaInP lower confinement layer may be a p-AlInP clad, and the active layer may have a band gap band that emits yellow light with a wavelength of 0.3 to 0.35 between U-AlxGa1-xInP / AlyGa1-yInP and quantum barrier AlyGa1 -yInP y has a band gap higher than the quantum well of> 0.5. The active layer may be an active layer alternately grown, and the AlGaInP upper confinement layer may be an N-AlInP clad.

In the practice of the present invention, the AlGaInP yellow light compensating section has a composition represented by AlxGa1-xInP so that yellow light having a peak wavelength of substantially 590 nm can be emitted by blue light, and X is 0.3 ± 0.1, preferably 0.3 0.05, more preferably 0.3 + - 0.02.

In the practice of the present invention, a lattice mismatch between the sapphire substrate and AlGaInP is eliminated on the upper surface of the sapphire substrate, and an AlAs buffer layer having a decreased crystallinity can be formed so that the AlGaInP light compensating portion can be directly grown by MOCVD have. The decrease in the crystallinity means that there are more recrystallized regions due to the external influence than the crystalline AlAs. The recrystallized region has a characteristic that the surface roughness is less than that of the crystalline AlAs region.

In the practice of the present invention, the crystallized AlAs buffer layer may be grown at a temperature lower than the normal growth temperature, and may be grown at a temperature lower than the growth temperature of the normal AlAs layer by 200 ° C or more, Can be achieved by low-temperature growth at 400 to 450 ° C.

In a preferred embodiment of the present invention, the AlAs buffer layer may be subjected to a low-temperature heat treatment for optimized crystalline state adjustment, which may be used as a buffer layer between the sapphire material and the AlGaInP material. The low-temperature heat treatment is performed at a temperature lower than or equal to the low-temperature growth temperature for several tens of minutes, preferably 10 to 20 minutes.

In the practice of the present invention, the thickness of each layer of the flip-type white diode is about 200 to 300 nm, the thickness of p-GaN is about 200 to 300 nm, the thickness of the GaN MQW is about AlInP thickness is about 300 nm, AlInP MQW thickness is about 200 nm, p-AlInP thickness is about 300 nm, and the n-AlInP thickness is about 300 nm. Do.

In the present invention, the AlGaInP yellow light compensation layer converts the wavelength of 450 nm of the GaN blue light emitting diode into white, which is a result of a conventional light interference phenomenon. As shown in FIG. 8, 450nm) and yellow (590nm) optical coupling. [ACS Applied Materials and Interfaces vol.6 p.19482 (2014)]

The present invention provides a flip-type white GaN light-emitting diode improved in optical characteristics and manufacturing process by applying an AlGaInP yellow light compensation layer to a flip-type white GaN light-emitting diode.

The present invention can directly apply an AlGaInP yellow diode structure to a transparent sapphire substrate used as a GaN light emitting diode substrate during epitaxial growth, so that it does not require a separate electrode or etching process, High productivity can be ensured.

1 is a cross-sectional view of a flip-type white diode according to the present invention.
FIG. 2 is a cross-sectional view illustrating a flip-type white diode according to the present invention mounted in a flip state.
FIG. 3 is a view illustrating a step of laminating a GaN light emitting portion in a manufacturing process of a flip-type white diode according to the present invention.
FIG. 4 is a view illustrating a step of laminating an AlGaInP light emitting portion in a manufacturing process of a flip-type white diode according to the present invention.
FIG. 5 is a view showing a step of etching a GaN light emitting portion and stacking the GaN light emitting portion in a flip shape in the manufacturing process of the flip-type white diode according to the present invention.
6 is a view showing a compensation relationship between blue light and red light.
7 is a diagram showing a white flip-type diode according to the prior art.

Hereinafter, the present invention will be described in detail with reference to examples. The following examples are intended to illustrate but not limit the present invention.

1, a flip chip 200 according to the present invention includes a sapphire substrate 210, a GaN light emitting portion 220 formed on a lower portion of the sapphire substrate 210, and a light emitting portion 220 formed on an upper portion of the sapphire substrate 210 And an AlGaInP optical compensation unit 230.

The flip chip 200 emits light from a power source applied to the GaN light emitting unit 220 through the electrodes and the AlGaInP light compensating unit 230 emits light from the GaN light emitting unit 220 As a result, the yellow light source emitted from the AlGaInP light compensating unit 230 compensates for the blue light source emitted from the GaN light emitting unit 220 to emit the white light source.

The GaN light emitting portion 220 includes an ITO transparent electrode 221 having a thickness of about 250 nm from the bottom, a p-GaN cladding 222 having a thickness of about 250 nm sequentially disposed on the ITO transparent electrode, GaN buffer 225 is formed on the upper surface of the U-GaN buffer 225, and a sapphire substrate (not shown) is formed on the upper surface of the U-GaN buffer 225. The GaN active layer 223, 210).

GaN light emitting part 220 has an etched part 226 etched from the ITO transparent electrode 221 to a part of the depth of the n-GaN cladding layer 224.

The AlGaInP optical compensator 230 includes a low temperature grown AlAs buffer 231 having a thickness of 50 nm, an n-AlInP cladding 232 having a thickness of about 300 nm, a U-Al0.3Ga0.7InP / Al0 An active layer 233 having a thickness of about 200 nm made of 0.5 GaP0.5P, and a p-AlInP clad 234 having a thickness of about 300 nm.

2, in the flip chip 200 according to the present invention, the ITO transparent electrode 221 and the n-GaN cladding 224 are soldered to the Si substrate 250 by the solder 240, Blue light is emitted from the GaN light emitting portion to partially excite the AlGaInP yellow active layer 233 after passing through the sapphire substrate 210 to induce Yellow light emission and thereby cause compensation of blue and yellow light White light is generated.

FIGS. 3 to 5 show a process of manufacturing a flip-type white GaN light-emitting diode 200 having an AlGaInP yellow light compensation layer 230.

As shown in FIG. 3, first, a GaN light emitting part is grown on a transparent sapphire substrate 210 in a metal organic chemical vapor deposition (MOCVD) system capable of high-quality growth.

A U-GaN buffer 225 having a thickness of about 3 탆 was grown on a transparent sapphire substrate 210 having a high lattice mismatch ratio at 550 캜 under low temperature growth to remove a gap between the sapphire and GaN, and an n-type GaN cladding layer 224, a U-InGaN / GaN active layer 223, and a p-type GaN cladding layer 222 are successively grown.

4, the AlGaInP yellow light compensating unit 230 is disposed on the GaN light emitting unit 220 of the transparent sapphire substrate 210 of the light emitting diode, and the GaN light emitting unit 220 is formed on the sapphire substrate 210, It was grown on the opposite side.

In order to solve the lattice mismatch between the sapphire substrate 210 and AlGaInP, an AlAs buffer layer 231 grown at a low temperature of 400 ° C on a sapphire substrate is formed. The AlAs buffer layer was heat-treated for 10 to 20 minutes at the same temperature as the low-temperature growth temperature to further lower the crystallinity.

An Al-AlInP cladding layer 232, a U-Al0.3GaInP / Al0.5GaInP active layer 233, and a P-AlInP cladding layer 234 are successively grown on the AlAs buffer layer 231. [

5, an ITO transparent electrode 221 is deposited on the bottom surface of the p-clad layer 222 to compensate the low conductivity of the p-GaN clad layer 222 prior to the formation of the electrode, A portion of the N-GaN cladding 224 was exposed through an ICP dry etching process. The manufactured flip chip 200 was seated on the final Si substrate by the solder ball 240.

Comparative Example 1

In the above embodiment, the same operation was performed except that a GaAs buffer layer was used instead of the AlAs buffer layer. The GaAs layer showed high crystallinity at 450 DEG C and the AlGaInP-based optical compensator could not be grown on the GaAs layer.

Comparative Example 2

In the above example, an AlGaAs buffer layer having an Al content of less than 70% was used instead of using an AlAs buffer layer. Low temperature growth was not achieved.

Comparative Example 3

In the above example, an AlGaAs buffer layer having an Al content of 70% or more was used instead of the AlAs buffer layer. When the content of Al was 70% or more, low temperature growth was achieved, but the buffer layer containing Ga absorbed light and the light efficiency was lowered.

200: Flip chip
210: Sapphire
220:
230: Optical compensation section
240: Solder
250: substrate

Claims (10)

Sapphire substrate;
A crystallized AlAs buffer layer grown on the upper surface of the sapphire substrate;
An AlGaInP optical compensator grown on the surface of the AlAs buffer layer;
A GaN light emitting portion grown at a lower portion of the sapphire substrate;
And an etch portion exposing an upper confinement layer formed on one side of the GaN light emitting portion,
Here, the GaN light emitting portion emits blue light by an applied power source,
The AlGaInP-based optical compensator compensates the blue light emitted from the GaN light-
Emits light, and
The diode is a device in which white light is emitted by blue light and yellow light
Features a white flip-type diode. The GaN light emitting device according to claim 1, wherein the GaN light emitting portion comprises: a GaN upper confinement layer grown on the lower surface of the sapphire substrate; a GaN active layer grown on the GaN upper confinement layer; And a GaN lower confinement layer grown in the GaN active layer. The flip-type white light emitting diode according to claim 1, wherein the GaN light emitting portion emits blue light having a peak wavelength of 450 mu m. The white LED of claim 1, wherein the GaN light emitting portion includes a U-GaN buffer layer located on a lower surface of the sapphire substrate. The white light emitting diode of claim 1, wherein the AlGaInP-based optical compensator has an AlGaInP lower limiting layer, an AlGaInP-based active layer grown in the lower limiting layer, and an upper limiting layer grown in the AlGaInP-based active layer. 6. The flip-type white light emitting diode according to claim 5, wherein the AlGaInP active layer has a layer represented by AlxGa1-xInP, wherein X is 0.3 +/- 0.1. The white LED of claim 1, wherein the AlGaInP-based optical compensator has an AlAs buffer layer grown at a low temperature on a sapphire substrate. The flip-type white light emitting diode according to claim 1, wherein a transparent electrode layer is disposed on a lower surface of the GaN light emitting portion. The flip-type white light emitting diode according to claim 1, wherein a power source is applied by soldering the lower surface of the GaN light emitting portion and the etching portion. Providing a sapphire substrate;
Growing a GaN light emitting portion emitting blue light at a lower portion of the sapphire substrate;
Etching a part of the GaN light emitting portion so that the upper limiting layer is exposed in the GaN light emitting portion;
Growing an AlAs buffer layer on the upper surface of the sapphire substrate and lowering the crystallinity by a low temperature heat treatment;
And growing an AlGaInP-based optical compensator on the upper surface of the AlAs buffer layer,
Here, the GaN light emitting portion emits blue light by a power source applied through a lower portion of the GaN light emitting portion and the etching portion, and the AlGaInP light compensating portion emits yellow light by the blue light emitted from the GaN light emitting portion. The diode emits blue light And the white light is emitted by the yellow light.

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