CN111261762A - Gallium nitride-based vertical structure light-emitting diode with current blocking layer and manufacturing method thereof - Google Patents
Gallium nitride-based vertical structure light-emitting diode with current blocking layer and manufacturing method thereof Download PDFInfo
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- CN111261762A CN111261762A CN202010201845.2A CN202010201845A CN111261762A CN 111261762 A CN111261762 A CN 111261762A CN 202010201845 A CN202010201845 A CN 202010201845A CN 111261762 A CN111261762 A CN 111261762A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor 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
- H01L33/36—Semiconductor 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
- H01L33/40—Materials therefor
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor 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
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0066—Processes for devices with an active region comprising only III-V compounds with a substrate not being a III-V compound
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor 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
- H01L33/005—Processes
- H01L33/0062—Processes for devices with an active region comprising only III-V compounds
- H01L33/0075—Processes for devices with an active region comprising only III-V compounds comprising nitride compounds
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor 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
- H01L33/36—Semiconductor 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
- H01L33/40—Materials therefor
- H01L33/405—Reflective materials
Abstract
The invention discloses a gallium nitride-based vertical structure light-emitting diode with a current barrier layer, which comprises: a conductive substrate located at the bottom layer; a second welding layer positioned on the surface of the conductive substrate; the first welding layer is positioned on the surface of the second welding layer; the diffusion barrier layer is positioned on the surface of the first welding layer; the nickel silver reflecting layer is positioned on the surface of the diffusion barrier layer; the Al layer is positioned on the surface of the diffusion barrier layer; the gallium nitride-based light-emitting epitaxial layer is positioned on the nickel silver reflecting layer and the surface of the Al layer; the LED light-emitting device comprises an n electrode positioned on the surface of the light-emitting epitaxial layer, an Al metal layer positioned in a projection area below the n electrode, and the Al metal layer serving as a current blocking layer changes current injection, so that the light-emitting efficiency is improved.
Description
Technical Field
The invention belongs to the field of semiconductors, and particularly relates to a gallium nitride-based vertical structure light-emitting diode with a current blocking layer and a manufacturing method thereof.
Background
In recent years, a vertical structure LED gains a place in the market because of good performance under the condition of large current injection, the vertical structure LED transfers a gallium nitride-based luminous layer to a secondary substrate with better heat conduction by removing a growth substrate, so that the heat dissipation performance under the condition of large current is improved.
Since the n-electrode of the vertical LED is on top and most of the light emitted by the injected current under the n-electrode is blocked by the electrode and cannot exit, the designer proposes the design idea of the current blocking layer. The CN200810237845 patent proposes a scheme of adopting a diffusion barrier layer in a local area and Ag to degrade through high temperature annealing, and when the scheme is implemented, it is necessary to ensure that Au is diffused to the surface of the current blocking area, and the reflectivity of Au is lower than that of Ag, which causes the reflectivity of the current blocking area to decrease, and reduces the light extraction efficiency. The solution disclosed in the published application No. 201811636723.5 is similar to the present invention, but the structure is slightly complicated, and when one or more layers of transparent dielectric materials are used as the current blocking layer, and the dielectric materials are used as the current blocking layer, because the difference between the thermal expansion coefficients of the common dielectric materials of semiconductors and the metal materials is large, and the adhesion between the dielectric materials and the metal materials is poor, the bonding difficulty is large during bonding, and bonding failure is easy to occur, so that the light emitting layer is peeled off.
Disclosure of Invention
The gallium nitride-based vertical structure light-emitting diode with the current blocking layer and the manufacturing method thereof overcome the defects, and the Al metal is used as the current blocking layer, so that the current distribution adjustment of the light-emitting layer is realized, the good light reflection is realized, and the method is simple and easy to realize.
The invention is realized by the following technical scheme:
a gallium nitride-based light emitting diode with a vertical structure comprises:
providing a conductive substrate;
covering a second welding layer on the upper surface of the conductive substrate;
a first welding layer covers the surface of the second welding layer;
covering a diffusion barrier layer on the surface of the first welding layer;
covering a nickel-silver metal layer on the partial surface area of the diffusion barrier layer to serve as a p-type ohmic contact reflection metal film;
covering an Al layer on the partial surface area of the diffusion barrier layer to serve as a current barrier layer for changing current injection;
the surfaces of the Al layer and the current barrier layer are covered with gallium nitride-based light-emitting epitaxial layers;
and partially covering the n electrode on the upper surface of the gallium nitride-based light-emitting epitaxial layer.
In the vertical light emitting diode structure, the innovation of the invention is that the n metal electrode is over against the lower surface area of the gallium nitride base epitaxy below, and an Al metal film is used as a current blocking layer instead of an insulating medium.
In order to achieve the above object, the present invention further provides a method for manufacturing a light emitting diode with a gallium nitride-based vertical structure, including:
1) growing a gallium nitride-based epitaxial layer, and sequentially growing an n-GaN layer, an MQW layer and a p-GaN layer on the sapphire substrate;
2) depositing a Ni/Ag layer on the p-GaN layer;
3) photoetching on the Ni/Ag layer;
4) carrying out wet etching on the Ni/Ag layer, and reserving the photoresist;
5) depositing an Al layer on the surface of the wafer with the adhesive;
6) stripping off the photoresist and the surface Al layer by a wet method;
7) forming a diffusion barrier layer on the surface of the Ni/Ag layer and the surface of the Al layer;
8) forming a first welding layer containing Au on the surface of the diffusion impervious layer;
9) providing a conductive substrate, and forming a second welding layer containing Au on the surface of the substrate;
10) pressurizing and heating the first welding layer and the second welding layer to enable the epitaxial layer and the conductive substrate to be connected together;
11) removing the sapphire substrate to expose the n-GaN layer;
12) coarsening the exposed n-GaN layer;
13) and forming an n electrode in a local area on the coarsened n-GaN layer.
In the steps of the invention, the pattern definition of the Al layer and the Ni/Ag layer is realized by adopting a self-aligned process and the pattern definition of the two films is completed by only adopting one-step photoetching, so that the two films can be ensured not to be overlapped, and the cost is reduced to be lower.
Drawings
Fig. 1 is a cross-sectional view of a vertical structure gan-based led according to an embodiment of the present invention.
Fig. 2-10 are schematic cross-sectional views illustrating a process for fabricating a vertical structure gallium nitride-based light emitting diode according to an embodiment.
Parts symbol description in the drawings:
101: sapphire substrate
102: n-GaN layer
103: MQW light emitting layer
104: p-GaN layer
120: diffusion barrier layer
121: first welding layer
130: Ni/Ag layer
140: layer of Al
150: n electrode
220: second solder layer
Detailed Description
The present invention will now be described in further detail with reference to specific examples, which are intended to be illustrative, but not limiting, of the invention.
The invention mainly aims to provide a vertical gallium nitride-based light emitting diode, which has a specific structure shown in figure 1, and adopts Al metal as a current blocking layer of the vertical gallium nitride-based light emitting diode. The Al metal is used as a current barrier layer and is mainly based on the following reasons: 1. when the heat treatment temperature is lower than 320 ℃, the Al metal and the surface of the p-GaN form non-ohmic contact, so that the Al metal can realize the current blocking; 2. the bonding process needs pressurization and heating, when the two are matched, the thermal expansion coefficients of Ag and Al are respectively 19.5E-6/K and 23.2E-6/K, the sizes are close, and in addition, the adhesion of Al and p-GaN is good, so that high-reliability bonding is easy to realize; 3. the reflectivity of Al is higher in the light-emitting waveband of the gallium nitride-based device. In conclusion, the scheme not only realizes the current blocking effect, but also realizes the maximum reflection light-emitting. When Ni is contacted with highly doped p-GaN, a better ohmic contact can be formed under the condition of no annealing, so that the Ni/Ag layer can form a reflecting electrode with good contact and high reflectivity.
Manufacturing a gallium nitride-based epitaxial wafer, and sequentially growing a 102n-GaN layer, a 103MQW light-emitting layer and a 104p-GaN layer on a 101 sapphire substrate; as shown in fig. 2.
Evaporating a 110Ni/Ag film as a reflecting layer on the 104p-GaN layer in a thickness of 1nm/200nm, photoetching by using negative photoresist to expose a region to be corroded, and corroding the Ni/Ag layer which is not covered by the photoresist by a wet method; as shown in fig. 3.
Evaporating Al metal on the surface of the epitaxial wafer formed in the previous step, then soaking an organic solvent, stripping off the photoresist and the Al metal on the surface of the photoresist, and forming a current blocking layer 140Al layer in a current blocking area, wherein the thickness is 201 nm; as shown in fig. 4.
A diffusion barrier layer 120Ti/Au and a first welding layer 121Ti/Au are sequentially evaporated on the surface of the epitaxial wafer formed in the previous step, wherein the thickness of 120 is 100nm/100nm, and the thickness of 121 is 250nm/500 nm; as shown in fig. 5.
Evaporating a second welding layer 220Ti/Au/AuSn on a 210 tungsten copper substrate, wherein the thickness of the second welding layer is 100nm/200nm/2500nm, and the ratio of Au to Sn of the AuSn is 80: 20; as shown in fig. 6.
Bonding a second metal connecting layer 220 on the surface of a 210 tungsten copper substrate and a 121 on the surface of an epitaxial wafer, heating to 295 ℃, pressurizing 3000N, and bonding into a whole; as shown in fig. 7.
Irradiating sapphire surface of epitaxial wafer with 248nm laser, and allowing the laser to penetrate the sapphire substrate to decompose gallium nitride at the interface between sapphire and gallium nitride into Ga metal and N2Removing the sapphire substrate 101; as shown in fig. 8.
Soaking the stripped wafer with the exposed n-type gallium nitride in 20% KOH solution heated to 75 ℃ to roughen the surface of the n-type gallium nitride; as shown in fig. 9.
Forming an n electrode 150Al/Ti/Au in the region opposite to the 140 on the 102n-GaN layer by photoetching and evaporation processes, wherein the thicknesses of the n electrode and the n electrode are 250nm/150nm/2000nm respectively; as shown in fig. 10.
The foregoing shows and describes the general principles and broad features of the present invention and advantages thereof. It will be understood by those skilled in the art that the present invention is not limited to the embodiments described above, which are described in the specification and illustrated only to illustrate the principle of the present invention, but that various changes and modifications may be made therein without departing from the spirit and scope of the present invention, which fall within the scope of the invention as claimed. The scope of the invention is defined by the appended claims and equivalents thereof.
Claims (10)
1. A gallium nitride-based vertical structure light emitting diode with a current blocking layer, the structure comprising:
providing a conductive substrate;
covering a second welding layer on the upper surface of the conductive substrate;
a first welding layer covers the surface of the second welding layer;
covering a diffusion barrier layer on the surface of the first welding layer;
covering a nickel-silver metal layer on the partial surface area of the diffusion barrier layer to serve as a p-type ohmic contact reflection metal film;
covering an aluminum layer on the partial surface area of the diffusion barrier layer to serve as a current barrier layer for changing current injection;
covering the surfaces of the aluminum layer and the current barrier layer with a gallium nitride-based epitaxial layer;
and covering the upper surface part of the gallium nitride-based epitaxial layer with an n electrode.
2. The light-emitting diode with the gallium nitride-based vertical structure and the current blocking layer according to claim 1, wherein: the gallium nitride-based epitaxial layer sequentially comprises an n-GaN layer, an MQW light-emitting layer and a p-GaN layer from top to bottom.
3. The light-emitting diode with the gallium nitride-based vertical structure and the current blocking layer according to claim 1, wherein: the aluminum layer is positioned in a projection area right below the n metal electrode and is not overlapped with the nickel silver layer, and the area of the aluminum layer is the same as or close to that of the n metal electrode.
4. The light-emitting diode with the gallium nitride-based vertical structure and the current blocking layer according to claim 1, wherein: the nickel-silver layer is composed of a nickel layer and a silver layer, the nickel layer covers the lower surface of the gallium nitride-based epitaxial layer, the silver layer covers the lower surface of the nickel layer, and the thickness of the nickel layer is 0.2-20 nm.
5. The light-emitting diode with the gallium nitride-based vertical structure and the current blocking layer according to claim 1, wherein: the thickness of the aluminum layer is the same as or close to that of the nickel silver layer.
6. The light-emitting diode with the gallium nitride-based vertical structure and the current blocking layer according to claim 2, wherein: the doping concentration of the p-GaN layer is more than or equal to 1019/cm3。
7. A method for manufacturing a gallium nitride-based vertical structure light-emitting diode with a current blocking layer comprises the following steps:
1) growing a gallium nitride-based epitaxial layer, and sequentially growing an n-GaN layer, an MQW layer and a p-GaN layer on the sapphire substrate;
2) depositing a Ni/Ag layer on the p-GaN layer;
3) photoetching on the Ni/Ag layer;
4) carrying out wet etching on the Ni/Ag layer, and reserving the photoresist;
5) depositing an Al layer on the surface of the wafer with the adhesive;
6) stripping off the photoresist and the surface Al layer by a wet method;
7) forming a diffusion barrier layer on the surface of the Ni/Ag layer and the surface of the Al layer;
8) forming a first welding layer containing Au on the surface of the diffusion impervious layer;
9) providing a conductive substrate, and forming a second welding layer containing Au on the surface of the substrate;
10) pressurizing and heating the first welding layer and the second welding layer to enable the epitaxial layer and the conductive substrate to be connected together;
11) removing the sapphire substrate to expose the n-GaN layer;
12) coarsening the exposed n-GaN layer;
13) and forming an n electrode in a local area on the coarsened n-GaN layer.
8. The method for manufacturing a light-emitting diode with a gallium nitride-based vertical structure according to claim 7, wherein: the highest temperature of the preparation process does not exceed 320 ℃.
9. The method for manufacturing a light-emitting diode with a gallium nitride-based vertical structure according to claim 7, wherein: the metal deposition method of steps 2) to 6) may be one or more of evaporation, sputtering, or electroplating.
10. The method for manufacturing a light-emitting diode with a gallium nitride-based vertical structure according to claim 7, wherein: the coarsening of the n-type layer is realized by adopting a solution containing KOH for wet etching, the molar concentration of the KOH is 2-20mol/L, and the etching temperature is 60-90 ℃.
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| CN202010201845.2A CN111261762A (en) | 2020-03-20 | 2020-03-20 | Gallium nitride-based vertical structure light-emitting diode with current blocking layer and manufacturing method thereof |
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Citations (6)
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| CN101494268A (en) * | 2008-11-24 | 2009-07-29 | 厦门市三安光电科技有限公司 | Preparation method for vertical LED with current countercheck structure |
| CN102047454A (en) * | 2008-04-16 | 2011-05-04 | Lg伊诺特有限公司 | Light-emitting device and fabricating method thereof |
| US20130328092A1 (en) * | 2009-05-04 | 2013-12-12 | Lg Innotek Co., Ltd. | Light emitting device, light emitting device package and lighting system including the same |
| CN104638069A (en) * | 2015-02-04 | 2015-05-20 | 映瑞光电科技(上海)有限公司 | Vertical LED (Light-Emitting Diode) chip structure and manufacturing method thereof |
| CN105609596A (en) * | 2015-09-11 | 2016-05-25 | 映瑞光电科技(上海)有限公司 | LED vertical chip possessing current blocking structure and manufacturing method thereof |
| CN109768137A (en) * | 2018-12-29 | 2019-05-17 | 晶能光电（江西）有限公司 | Light emitting diode (LED) chip with vertical structure and preparation method thereof |
-
2020
- 2020-03-20 CN CN202010201845.2A patent/CN111261762A/en active Pending
Patent Citations (6)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102047454A (en) * | 2008-04-16 | 2011-05-04 | Lg伊诺特有限公司 | Light-emitting device and fabricating method thereof |
| CN101494268A (en) * | 2008-11-24 | 2009-07-29 | 厦门市三安光电科技有限公司 | Preparation method for vertical LED with current countercheck structure |
| US20130328092A1 (en) * | 2009-05-04 | 2013-12-12 | Lg Innotek Co., Ltd. | Light emitting device, light emitting device package and lighting system including the same |
| CN104638069A (en) * | 2015-02-04 | 2015-05-20 | 映瑞光电科技(上海)有限公司 | Vertical LED (Light-Emitting Diode) chip structure and manufacturing method thereof |
| CN105609596A (en) * | 2015-09-11 | 2016-05-25 | 映瑞光电科技(上海)有限公司 | LED vertical chip possessing current blocking structure and manufacturing method thereof |
| CN109768137A (en) * | 2018-12-29 | 2019-05-17 | 晶能光电（江西）有限公司 | Light emitting diode (LED) chip with vertical structure and preparation method thereof |
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