CN113851566A - Deep ultraviolet LED flip chip and manufacturing method thereof - Google Patents
Deep ultraviolet LED flip chip and manufacturing method thereof Download PDFInfo
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- CN113851566A CN113851566A CN202111448886.2A CN202111448886A CN113851566A CN 113851566 A CN113851566 A CN 113851566A CN 202111448886 A CN202111448886 A CN 202111448886A CN 113851566 A CN113851566 A CN 113851566A
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers 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 having potential barriers 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
- H01L33/38—Semiconductor devices having potential barriers 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 with a particular shape
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- H—ELECTRICITY
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- H01L33/00—Semiconductor devices having potential barriers 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 having potential barriers 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
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- H—ELECTRICITY
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- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
- H01L33/48—Semiconductor devices having potential barriers 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
- H01L33/64—Heat extraction or cooling elements
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Abstract
The invention relates to a deep ultraviolet LED flip chip and a manufacturing method thereof, wherein the deep ultraviolet LED flip chip comprises an LED epitaxial wafer, an n electrode (8) and a p electrode (9), the n electrode (8) is provided with an n current expansion electrode (10), the p electrode (9) is provided with a p current expansion electrode (11), the edge of the orthographic projection of the n current expansion electrode (10) is retracted by 2-7um relative to the edge of the orthographic projection of the n electrode (8), and the edge of the orthographic projection of the p current expansion electrode (11) is retracted by 2-7um relative to the edge of the orthographic projection of the p electrode (9). The service life of the deep ultraviolet LED flip chip can be prolonged, and the luminous intensity of the deep ultraviolet LED flip chip can be improved.
Description
Technical Field
The invention belongs to the technical field of semiconductor chip manufacturing, relates to an LED (light emitting diode) chip and a manufacturing method thereof, and particularly relates to a deep ultraviolet LED flip chip and a manufacturing method thereof.
Background
In recent years, with the progress of the global LED industry technology, the LED light-emitting waveband is expanded from a visible light waveband to an ultraviolet and deep ultraviolet waveband. The ultraviolet LED has the functions of photocatalysis, medical phototherapy, health care, air purification, sterilization and the like. Particularly, in 2020, the outbreak of the global novel coronavirus epidemic situation, and the deep ultraviolet LED has the functions of quick sterilization and disinfection, so that the deep ultraviolet LED has a wide market prospect.
At present, after research and development for more than 10 years, the external quantum efficiency of deep ultraviolet LEDs below 280nm exceeds 5%, the corresponding luminous power is more than 5mW, and the service life reaches 5000 h. However, the external quantum efficiency is far from 60% for blue LEDs of InGaN material.
At present, an electrode of a deep ultraviolet LED chip is generally manufactured by using a flip structure. The flip chip structure has strong absorption to deep ultraviolet light because P type GaN, and simultaneously in the process that light is transmitted out from the back, the light-emitting efficiency is low and the brightness is low because of the light absorption phenomenon between the material of the internal contact layer in the deep ultraviolet LED epitaxial wafer and the epitaxial layer structure. Meanwhile, the n electrode and the p electrode are positioned on the same side of the epitaxial wafer, and the current congestion phenomenon still exists, so that the chip has poor heat dissipation, short service life and low external quantum efficiency, and most electric energy is converted into heat energy.
For manufacturing electrodes of the deep ultraviolet LED chip, a flip structure is adopted, and a layer of silicon oxide insulating medium is plated below an n electrode to serve as a current blocking layer. Although this can reduce the current ratio under the n-electrode and increase the current diffusivity to some extent, increasing the current blocking layer also limits the formation of the process.
In view of the above technical defects in the prior art, it is urgently needed to develop a novel deep ultraviolet LED flip chip and a manufacturing method thereof.
Disclosure of Invention
In order to overcome the defects of the prior art, the invention provides a deep ultraviolet LED flip chip and a manufacturing method thereof, which can prolong the service life of the deep ultraviolet LED flip chip and improve the luminous intensity of the deep ultraviolet LED flip chip.
In order to achieve the above object, the present invention provides a deep ultraviolet LED flip chip, which includes an LED epitaxial wafer, and an n-electrode and a p-electrode both disposed on the LED epitaxial wafer, and is characterized in that an n-current spreading electrode is disposed on the n-electrode, a p-current spreading electrode is disposed on the p-electrode, an edge of an orthographic projection of the n-current spreading electrode is recessed by 2-7um relative to an edge of an orthographic projection of the n-electrode, and an edge of an orthographic projection of the p-current spreading electrode is recessed by 2-7um relative to an edge of an orthographic projection of the p-electrode.
Preferably, wherein the edge of the orthographic projection of the n-current spreading electrode is recessed by 4um relative to the edge of the orthographic projection of the n-electrode and the edge of the orthographic projection of the p-current spreading electrode is recessed by 4um relative to the edge of the orthographic projection of the p-electrode.
Preferably, wherein, n electric current extension electrode and p electric current extension electrode have the hole that the array was arranged, the diameter of hole is 3-5um and adjacent two interval between the hole is 5-7 um.
Preferably, the n current spreading electrode and the p current spreading electrode are formed by evaporation of a metal system Cr/Al/Ti/Au/Ti.
Preferably, in the n current spreading electrode and the p current spreading electrode, the thickness of the Cr film is 20-50nm, the thickness of the Al film is 20-60nm, the thickness of the middle Ti film is 10-30nm, the thickness of the Au film is 40-50nm, and the thickness of the top Ti film is 5-10 nm.
Preferably, the n-electrode is formed by evaporation of a metal system Ti/Al/Ti/Au, the thickness of the bottom Ti film is 20nm, the thickness of the Al film is 60nm, the thickness of the middle Ti film is 50nm, and the thickness of the Au film is 20 nm.
Preferably, the p-electrode is formed by evaporation of a metal system Ni/Au/Ti, and the thickness of the Ni film is 10nm, the thickness of the Au film is 200nm, and the thickness of the Ti film is 20 nm.
Preferably, the LED epitaxial wafer includes a substrate, and an aluminum nitride template layer, a superlattice stress buffer layer, an n-type AlGaN layer, a multi-quantum hydrazine structure layer, an electron blocking layer, and a P-type hole conduction layer sequentially formed on the substrate, where the n electrode is disposed on the n-type AlGaN layer, and the P electrode is disposed on the P-type hole conduction layer.
Preferably, a pad electrode is vapor-deposited on each of the n-current spreading electrode and the p-current spreading electrode.
Preferably, a passivation layer is disposed between the two pad electrodes, between the n-current spreading electrode and the p-current spreading electrode, and between the n-electrode and the p-electrode.
In addition, the invention also provides a manufacturing method of the deep ultraviolet LED flip chip, which is characterized by comprising the following steps:
1) sequentially growing an aluminum nitride template layer, a superlattice stress buffer layer, an n-type AlGaN layer, a multi-quantum hydrazine structural layer, an electron blocking layer and a P-type hole conducting layer on the substrate to obtain an LED epitaxial wafer;
2) etching part of the LED epitaxial wafer downwards until the n-type AlGaN layer is etched to form an n-electrode table top, and forming a P-electrode table top at the un-etched part;
3) obtaining an n electrode on the surface of the n electrode table board by a photoetching and evaporation method;
4) obtaining a P electrode on the surface of the P electrode table board by a photoetching and evaporation method;
5) manufacturing an n current expansion electrode on the n electrode through photoetching and evaporation process, manufacturing a p current expansion electrode on the p electrode, and enabling the edge of the orthographic projection of the n current expansion electrode to be retracted by 2-7um relative to the edge of the orthographic projection of the n electrode, and enabling the edge of the orthographic projection of the p current expansion electrode to be retracted by 2-7um relative to the edge of the orthographic projection of the p electrode;
6) manufacturing a passivation layer through deposition, photoetching and etching processes;
7) and forming through holes respectively opposite to the n current expansion electrode and the p current expansion electrode on the passivation layer, and evaporating pad electrodes connected with the n current expansion electrode and the p current expansion electrode in the through holes respectively.
Preferably, wherein, n electric current extension electrode and p electric current extension electrode have the hole that the array was arranged, the diameter of hole is 3-5um and adjacent two interval between the hole is 5-7 um.
Preferably, the n current spreading electrode and the p current spreading electrode are formed by evaporation of a metal system Cr/Al/Ti/Au/Ti, and in the n current spreading electrode and the p current spreading electrode, the thickness of a Cr film is 20-50nm, the thickness of an Al film is 20-60nm, the thickness of a middle Ti film is 10-30nm, the thickness of an Au film is 40-50nm, and the thickness of a top Ti film is 5-10 nm.
Preferably, wherein, after obtaining the N-electrode, the N-electrode is made to be at N2And carrying out high-temperature annealing in the atmosphere, wherein the annealing temperature is 900 ℃, and the annealing time is 30 s.
Preferably, wherein, after obtaining the p-electrode, the p-electrode is made to be N2Or annealing in air atmosphere, wherein the annealing temperature is 550 ℃ and the annealing time is 180 s.
Compared with the prior art, the deep ultraviolet LED flip chip and the manufacturing method thereof have one or more of the following beneficial technical effects:
1. it has n electric current extension electrode and p electric current extension electrode, and the edge of the orthographic projection of n electric current extension electrode contracts in for the edge of the orthographic projection of n electrode, the edge of the orthographic projection of p electric current extension electrode contracts in for the edge of the orthographic projection of p electrode, thus, when fully guaranteeing ohmic contact, the phenomenon that the electric current of flip structure concentrates and blocks up intensively is reduced, very big reduction deep ultraviolet LED flip chip's operating voltage, the heat radiating area of deep ultraviolet LED flip chip has been increased, the life-span of deep ultraviolet LED flip chip is prolonged.
2. The n current spreading electrode and the p current spreading electrode are provided with holes arranged in an array mode, and a metal system with a reflection effect is evaporated, so that light can oscillate back and forth in the holes of the reflection metal when transversely propagating, light with the wavelength matched with a window can be enhanced, and the luminous intensity of the deep ultraviolet LED flip chip is improved.
3. The manufacturing process related by the invention is a conventional process and is easy to realize.
Drawings
Fig. 1 is a schematic structural diagram of a deep ultraviolet LED flip chip of the present invention.
Fig. 2 is a flow chart of a manufacturing method of the deep ultraviolet LED flip chip of the present invention.
Detailed Description
The present invention is further described with reference to the following drawings and examples, which are not intended to limit the scope of the present invention.
Aiming at the problems of high working voltage and low external quantum efficiency of the current deep ultraviolet inverted structure, the invention adds the current expansion layer on the traditional ohmic contact p/n electrode, and the current expansion layer is composed of special patterns of holes of reflective metal, so that the service life of the deep ultraviolet LED inverted chip can be prolonged, and the luminous intensity of the deep ultraviolet LED inverted chip can be improved.
Fig. 1 shows a schematic structural diagram of a deep ultraviolet LED flip chip of the present invention. As shown in fig. 1, the deep ultraviolet LED flip chip of the present invention includes an LED epitaxial wafer, and an n-electrode 8 and a p-electrode 9 disposed on the LED epitaxial wafer.
Preferably, the LED epitaxial wafer comprises a substrate 1, and an aluminum nitride template layer 2, a superlattice stress buffer layer 3, an n-type AlGaN layer 4, a multi-quantum hydrazine structure layer 5, an electron blocking layer 6 and a P-type hole conduction layer 7 which are sequentially formed on the substrate 1. The superlattice stress buffer layer 3 may be made of AlN or AlGaN. The electron blocking layer 6 may be a p-AlGaN layer. The P-type hole conduction layer 7 may be a P-GaN layer.
The n-electrode 8 is provided on the n-type AlGaN layer 4. The P-electrode 9 is disposed on the P-type hole conduction layer 7.
Preferably, the n-electrode 8 is formed by evaporation of a metal system of Ti/Al/Ti/Au, and the thickness of the bottom Ti film is 20nm, the thickness of the Al film is 60nm, the thickness of the middle Ti film is 50nm, and the thickness of the Au film is 20 nm.
More preferably, the p-electrode 9 is formed by vapor deposition of a metal system Ni/Au/Ti, and the Ni film has a thickness of 10nm, the Au film has a thickness of 200nm, and the Ti film has a thickness of 20 nm.
In the present invention, the n-electrode 8 is provided with an n-current spreading electrode 10. The edge of the orthographic projection of the n current spreading electrode 10 is retracted by 2-7um relative to the edge of the orthographic projection of the n electrode 8. That is, when looking down from the top, the area of the n current spreading electrode 10 is smaller than the area of the n electrode 8 and the distance between the edge of the n current spreading electrode 10 and the edge of the n electrode 8 is 2-7 um.
Preferably, the edge of the forward projection of the n-current spreading electrode 10 is recessed by 4um with respect to the edge of the forward projection of the n-electrode 8.
The p-electrode 9 is provided with a p-current spreading electrode 11. The edge of the orthographic projection of the p-current spreading electrode 11 is also indented by 2-7um relative to the edge of the orthographic projection of the p-electrode 9. That is, when looking down from the top, the area of the p-current extension electrode 11 is smaller than the area of the p-electrode 9 and the distance between the edge of the p-current extension electrode 11 and the edge of the p-electrode 9 is 2-7 um.
Preferably, the edge of the forward projection of the p-current spreading electrode 11 is recessed by 4um relative to the edge of the forward projection of the p-electrode 9.
Like this, the edge of the orthographic projection of n electric current extension electrode 10 contracts in the edge of the orthographic projection of n electrode 8, the edge of the orthographic projection of p electric current extension electrode 11 contracts in the edge of the orthographic projection of p electrode 9, on the one hand when fully guaranteeing ohmic contact, has reduced the intensive phenomenon of concentrating and blocking up of current of flip structure, and very big reduction deep ultraviolet LED flip chip's operating voltage has increased deep ultraviolet LED flip chip's heat radiating area, has prolonged deep ultraviolet LED flip chip's life-span.
In the present invention, the n current spreading electrode 10 and the p current spreading electrode 11 have holes arranged in an array. The diameter of hole is 3-5um and adjacent two interval between the hole is 5-7 um.
Further, the n-current spreading electrode 10 and the p-current spreading electrode 11 are formed by vapor deposition of a highly reflective metal system, for example, a metal system of Cr/Al/Ti/Au/Ti, that is, a stack of a Cr film, an Al film, an intermediate Ti film, an Au film, and a top Ti film.
The Cr metal has good adhesion and conductivity, is beneficial to current transmission, has low requirement on vacuum degree for evaporating Cr, and a high-purity Cr source is easy to find. In the present invention, the thickness of the Cr film is made to be 20 to 50 nm.
The reflectivity of Al metal in a deep ultraviolet band is 60-70 percent, the reflectivity is higher, meanwhile, the cost of Al is very low, and the Al plays a role of a reflecting electrode. In the present invention, the thickness of the Al film is 20 to 60 nm.
Since Ti metal has a high resistivity, it is not preferable that the Ti film is too thick. In the present invention, the thickness of the intermediate Ti film is 10 to 30 nm.
The Au metal is a protective layer and has good stability in air. In the present invention, the thickness of the Au film is 40 to 50 nm.
Because of Au and SiO2The wettability is poor, and the deep ultraviolet LED flip chip process generally needs SiO on an electrode2Passivation protection, SiO2When the protective layer exceeds 500nm, cracks often appear when the protective layer is deposited on the Au layer, the passivation significance is lost, and the electric leakage yield of the deep ultraviolet LED flip chip is reduced. Therefore, there is a need for a stable in air SiO-based Au layer2The metal Ti has good affinity and wettability. In the invention, the thickness of the top Ti film is 5-10 nm.
Therefore, the n current spreading electrode 10 and the p current spreading electrode 11 are provided with holes arranged in an array mode, and a metal system with a high reflection effect is evaporated, so that the n current spreading electrode and the p current spreading electrode can oscillate back and forth in the holes of the high reflection metal when light is transversely transmitted, light with a wavelength matched with a window can be enhanced, and the luminous intensity of the deep ultraviolet LED flip chip is improved.
In the present invention, a pad electrode 13 is deposited on each of the n-current spreading electrode 10 and the p-current spreading electrode 11. The pad electrode 13 facilitates connection of an external power source, thereby facilitating power supply thereto for light emission thereof.
Further, passivation layers 12 are provided between the two pad electrodes 13, between the n-current spreading electrode 10 and the p-current spreading electrode 11, and between the n-electrode 8 and the p-electrode 9. The passivation layer 12 can prevent the pad electrodes 13, the n-current spreading electrode 10 and the p-current spreading electrode 11, and the n-electrode 8 and the p-electrode 9 from contacting each other to cause electric leakage, thereby protecting the pad electrodes.
Preferably, the passivation layer 12 is SiO2And a passivation layer.
The method for manufacturing the deep ultraviolet LED flip chip of the present invention is described below, so that those skilled in the art can manufacture the deep ultraviolet LED flip chip according to the description of the present invention.
Fig. 2 shows a flow chart of a manufacturing method of the deep ultraviolet LED flip chip of the present invention. As shown in fig. 2, the manufacturing method of the deep ultraviolet LED flip chip of the present invention includes the following steps:
firstly, preparing an LED epitaxial wafer.
Similar to the prior art, when an LED epitaxial wafer is prepared, a substrate 1 is provided, and an aluminum nitride template layer 2, a superlattice stress buffer layer 3, an n-type AlGaN layer 4, a multi-quantum hydrazine structure layer 5, an electron blocking layer 6 and a P-type hole conduction layer 7 are sequentially grown on the substrate 1.
And secondly, preparing an n electrode table top and a p electrode table top.
Before the n-electrode table top and the p-electrode table top are prepared, the prepared LED epitaxial wafer can be cleaned, so that impurities on the LED epitaxial wafer can be removed conveniently.
In the cleaning, cleaning may be performed using an inorganic solvent, an organic solvent (e.g., a sulfuric acid/hydrogen peroxide mixed solution, an isopropyl alcohol solution), or the like.
When the n electrode table top and the p electrode table top are prepared, parts of the LED epitaxial wafer can be etched from top to bottom by adopting methods such as photoetching, dry etching and the like. As shown in fig. 1, during etching, the n-type AlGaN layer 4 needs to be etched, that is, the P-type hole conducting layer 7, the electron blocking layer 6, and the multi-quantum hydrazine structure layer 5 need to be etched away until the n-type AlGaN layer 4 is exposed, so as to form an n-electrode mesa.
If necessary, the etching may be performed only to the surface of the n-type AlGaN layer 4, or a part of the n-type AlGaN layer 4 may be etched away, and only a part of the thickness of the n-type AlGaN layer 4 may be left.
According to the thickness of each layer in the LED epitaxial wafer, preferably, when the LED epitaxial wafer is etched, the etching depth is 500-800 nm. More preferably, the etch depth is 600 nm.
Meanwhile, the p electrode mesa is formed by the unetched part.
And thirdly, preparing the n electrode 8.
In the present invention, the n-electrode 8 can be obtained on the exposed n-type AlGaN layer 4, that is, on the n-electrode mesa, by photolithography and evaporation processes.
Preferably, the n-electrode 8 is formed by evaporation of a metal system of Ti/Al/Ti/Au, and the thickness of the bottom Ti film is 20nm, the thickness of the Al film is 60nm, the thickness of the middle Ti film is 50nm, and the thickness of the Au film is 20 nm.
More preferably, after obtaining the N-electrode 8, the N-electrode 8 is made to be N2And carrying out high-temperature annealing in the atmosphere. Wherein the annealing temperature is 900 ℃, and the annealing time is 30 s.
And fourthly, preparing the p electrode 9.
In the present invention, the P-electrode 9 can be fabricated on the P-type GaN hole conduction layer 7, that is, the P-electrode mesa, by photolithography and evaporation processes.
Preferably, the p-electrode 9 is formed by vapor deposition of a metal system of Ni/Au/Ti, and the Ni film has a thickness of 10nm, the Au film has a thickness of 200nm, and the Ti film has a thickness of 20 nm.
More preferably, after obtaining the p-electrode 9, the p-electrode 9 is made to be N2Or annealing in an air atmosphere. Wherein the annealing temperature is 550 ℃ and the annealing time is 180 s.
And fifthly, preparing an n current spreading electrode 10 and a p current spreading electrode 11.
In the present invention, the n current spreading electrode 10 may be fabricated on the n electrode 8 by photolithography and evaporation processes. A p-current spreading electrode 11 is formed on the p-electrode 9.
Wherein the edge of the orthographic projection of the n current spreading electrode 10 is retracted by 2-7um relative to the edge of the orthographic projection of the n electrode 8. That is, when looking down from the top, the area of the n current spreading electrode 10 is smaller than the area of the n electrode 8 and the distance between the edge of the n current spreading electrode 10 and the edge of the n electrode 8 is 2-7 um.
Preferably, the edge of the forward projection of the n-current spreading electrode 10 is recessed by 4um with respect to the edge of the forward projection of the n-electrode 8.
And the orthographic projection edge of the p current spreading electrode 11 is also retracted by 2-7um relative to the orthographic projection edge of the p electrode 9. That is, when looking down from the top, the area of the p-current extension electrode 11 is smaller than the area of the p-electrode 9 and the distance between the edge of the p-current extension electrode 11 and the edge of the p-electrode 9 is 2-7 um.
Preferably, the edge of the forward projection of the p-current spreading electrode 11 is recessed by 4um relative to the edge of the forward projection of the p-electrode 9.
Like this, the edge of the orthographic projection of n electric current extension electrode 10 contracts in the edge of the orthographic projection of n electrode 8, the edge of the orthographic projection of p electric current extension electrode 11 contracts in the edge of the orthographic projection of p electrode 9, on the one hand when fully guaranteeing ohmic contact, has reduced the intensive phenomenon of concentrating and blocking up of current of flip structure, and very big reduction deep ultraviolet LED flip chip's operating voltage has increased deep ultraviolet LED flip chip's heat radiating area, has prolonged deep ultraviolet LED flip chip's life-span.
In addition, in the present invention, the n-current spreading electrode 10 and the p-current spreading electrode 11 have holes arranged in an array. The diameter of hole is 3-5um and adjacent two interval between the hole is 5-7 um.
Further, the n-current spreading electrode 10 and the p-current spreading electrode 11 are formed by vapor deposition of a highly reflective metal system, for example, a metal system of Cr/Al/Ti/Au/Ti, that is, a stack of a Cr film, an Al film, an intermediate Ti film, an Au film, and a top Ti film.
The Cr metal has good adhesion and conductivity, is beneficial to current transmission, has low requirement on vacuum degree for evaporating Cr, and a high-purity Cr source is easy to find. In the present invention, the thickness of the Cr film is made to be 20 to 50 nm.
The reflectivity of Al metal in a deep ultraviolet band is 60-70 percent, the reflectivity is higher, meanwhile, the cost of Al is very low, and the Al plays a role of a reflecting electrode. In the present invention, the thickness of the Al film is 20 to 60 nm.
Since Ti metal has a high resistivity, it is not preferable that the Ti film is too thick. In the present invention, the thickness of the intermediate Ti film is 10 to 30 nm.
The Au metal is a protective layer and has good stability in air. In the present invention, the thickness of the Au film is 40 to 50 nm.
Because of Au and SiO2The wettability is poor, and the deep ultraviolet LED flip chip process generally needs SiO on an electrode2Passivation protection, SiO2When the protective layer exceeds 500nm, cracks often appear when the protective layer is deposited on the Au layer, the passivation significance is lost, and the electric leakage yield of the deep ultraviolet LED flip chip is reduced. Therefore, there is a need for a stable in air SiO-based Au layer2The metal Ti has good affinity and wettability. In the invention, the thickness of the top Ti film is 5-10 nm.
Therefore, the n current spreading electrode 10 and the p current spreading electrode 11 are provided with holes arranged in an array mode, and a metal system with a high reflection effect is evaporated, so that the n current spreading electrode and the p current spreading electrode can oscillate back and forth in the holes of the high reflection metal when light is transversely transmitted, light with a wavelength matched with a window can be enhanced, and the luminous intensity of the deep ultraviolet LED flip chip is improved.
Sixthly, preparing a passivation layer 12.
That is, after the n-current spreading electrode 10 and the p-current spreading electrode 11 are prepared, the passivation layer 12 is manufactured through deposition, photolithography, and etching processes.
Preferably, the passivation layer 12 is a silicon oxide layer. By preparing the passivation layer 12, it is possible to prevent electric leakage caused by contact between the two pad electrodes 13, between the n-current spreading electrode 10 and the p-current spreading electrode 11, and between the n-electrode 8 and the p-electrode 9, and thus it is possible to perform a protective function.
And seventhly, preparing the pad electrode 13.
Two through holes respectively opposite to the n current spreading electrode 10 and the p current spreading electrode 11 may be formed on the passivation layer 12 by using a photolithography method, a dry etching method, or the like. Then, the pad electrodes 13 connected to the n-current spreading electrode 10 and the p-current spreading electrode 11 are respectively evaporated in the through holes by an evaporation process.
After the pad electrode 13 is prepared, the manufacturing process of the deep ultraviolet LED flip chip of the present invention is completed.
Finally, it should be noted that the above embodiments are only used for illustrating the technical solutions of the present invention, and do not limit the protection scope of the present invention. Those skilled in the art can make modifications or equivalent substitutions to the technical solution of the present invention without departing from the spirit and scope of the technical solution of the present invention.
Claims (15)
1. The utility model provides a deep ultraviolet LED flip chip, it includes the LED epitaxial wafer and sets up n electrode (8) and p electrode (9) on the LED epitaxial wafer, its characterized in that, be equipped with n electric current extension electrode (10) on n electrode (8), be equipped with p electric current extension electrode (11) on p electrode (9), the orthographic projection's of n electric current extension electrode (10) edge for the orthographic projection's of n electrode (8) edge is retracted 2-7um just the orthographic projection's of p electric current extension electrode (11) edge for the orthographic projection's of p electrode (9) edge is retracted 2-7 um.
2. The deep ultraviolet LED flip chip according to claim 1, characterized in that the edge of the orthographic projection of the n-current spreading electrode (10) is recessed by 4um with respect to the edge of the orthographic projection of the n-electrode (8) and the edge of the orthographic projection of the p-current spreading electrode (11) is recessed by 4um with respect to the edge of the orthographic projection of the p-electrode (9).
3. The deep ultraviolet LED flip chip according to claim 1, wherein the n current spreading electrode (10) and the p current spreading electrode (11) have holes arranged in an array, the holes have a diameter of 3-5um and a distance between two adjacent holes is 5-7 um.
4. The deep ultraviolet LED flip chip according to claim 3, characterized in that the n-current spreading electrode (10) and the p-current spreading electrode (11) are evaporated from the metallic system Cr/Al/Ti/Au/Ti.
5. The deep ultraviolet LED flip chip as claimed in claim 4, wherein in the n current spreading electrode (10) and the p current spreading electrode (11), the thickness of the Cr film is 20-50nm, the thickness of the Al film is 20-60nm, the thickness of the middle Ti film is 10-30nm, the thickness of the Au film is 40-50nm, and the thickness of the top Ti film is 5-10 nm.
6. The deep ultraviolet LED flip chip according to claim 1, characterized in that the n-electrode (8) is formed by evaporation of a metal system Ti/Al/Ti/Au, and the thickness of the bottom Ti film is 20nm, the thickness of the Al film is 60nm, the thickness of the middle Ti film is 50nm, and the thickness of the Au film is 20 nm.
7. The deep ultraviolet LED flip chip according to claim 1, characterized in that the p-electrode (9) is formed by evaporation of a metal system Ni/Au/Ti, and the thickness of the Ni film is 10nm, the thickness of the Au film is 200nm, and the thickness of the Ti film is 20 nm.
8. The deep ultraviolet LED flip chip according to claim 1, characterized in that the LED epitaxial wafer comprises a substrate (1) and an aluminum nitride template layer (2), a superlattice stress buffer layer (3), an n-type AlGaN layer (4), a multi-quantum hydrazine structure layer (5), an electron blocking layer (6) and a P-type hole conduction layer (7) which are sequentially formed on the substrate (1), and the n-electrode (8) is disposed on the n-type AlGaN layer (4), and the P-electrode (9) is disposed on the P-type hole conduction layer (7).
9. The deep ultraviolet LED flip chip according to claim 1, characterized in that a pad electrode (13) is evaporated on each of the n current spreading electrode (10) and the p current spreading electrode (11).
10. The deep ultraviolet LED flip chip according to claim 9, characterized in that a passivation layer (12) is provided between the two pad electrodes (13), between the n-current spreading electrode (10) and the p-current spreading electrode (11), and between the n-electrode (8) and the p-electrode (9).
11. A manufacturing method of a deep ultraviolet LED flip chip is characterized by comprising the following steps:
1) sequentially growing an aluminum nitride template layer (2), a superlattice stress buffer layer (3), an n-type AlGaN layer (4), a multi-quantum hydrazine structure layer (5), an electron blocking layer (6) and a P-type hole conducting layer (7) on a substrate (1) to obtain an LED epitaxial wafer;
2) etching part of the LED epitaxial wafer downwards until the n-type AlGaN layer (4) is etched to form an n-electrode table top, and forming a P-electrode table top at the un-etched part;
3) obtaining an n electrode (8) on the surface of the n electrode table board by a photoetching and evaporation method;
4) obtaining a P electrode (9) on the surface of the P electrode table board by a photoetching and evaporation method;
5) manufacturing an n current spreading electrode (10) on the n electrode (8) through a photoetching and evaporation process, manufacturing a p current spreading electrode (11) on the p electrode (9), and enabling the edge of the orthographic projection of the n current spreading electrode (10) to be retracted by 2-7um relative to the edge of the orthographic projection of the n electrode (8), and enabling the edge of the orthographic projection of the p current spreading electrode (11) to be retracted by 2-7um relative to the edge of the orthographic projection of the p electrode (9);
6) manufacturing a passivation layer (12) by deposition, photoetching and etching processes;
7) and forming through holes respectively opposite to the n current spreading electrode (10) and the p current spreading electrode (11) on the passivation layer (12) and evaporating pad electrodes (13) connected with the n current spreading electrode (10) and the p current spreading electrode (11) in the through holes respectively.
12. The manufacturing method of the deep ultraviolet LED flip chip as claimed in claim 11, wherein the n current spreading electrode (10) and the p current spreading electrode (11) have holes arranged in an array, the diameter of the holes is 3-5um, and the distance between two adjacent holes is 5-7 um.
13. The method for manufacturing the deep ultraviolet LED flip chip according to claim 11, wherein the n current spreading electrode (10) and the p current spreading electrode (11) are formed by evaporation of a metal system Cr/Al/Ti/Au/Ti, and in the n current spreading electrode (10) and the p current spreading electrode (11), the thickness of a Cr film is 20-50nm, the thickness of an Al film is 20-60nm, the thickness of a middle Ti film is 10-30nm, the thickness of an Au film is 40-50nm, and the thickness of a top Ti film is 5-10 nm.
14. The method for manufacturing the deep ultraviolet LED flip chip according to claim 11, wherein the N electrode (8) is N after the N electrode (8) is obtained2And carrying out high-temperature annealing in the atmosphere, wherein the annealing temperature is 900 ℃, and the annealing time is 30 s.
15. The method for manufacturing the deep ultraviolet LED flip chip according to claim 11, wherein the p-electrode (9) is N after the p-electrode (9) is obtained2Or annealing in air atmosphere, wherein the annealing temperature is 550 ℃ and the annealing time is 180 s.
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