A vertical structure deep ultraviolet LED device and a preparation method thereof

Abstract

This application discloses a vertical-structure deep ultraviolet (DUV) LED device and its fabrication method, relating to the field of semiconductor device technology. The fabrication method of the vertical-structure DUV LED device includes: providing a composite substrate and forming a light-emitting epitaxial wafer on the composite substrate; etching the light-emitting epitaxial wafer to form nanopores, forming a photonic crystal structure; depositing a first passivation layer within the nanopores and depositing Al metal particles; filling the nanopores with a passivation material; depositing a P-electrode and an Al metal mirror, connecting them to a conductive substrate through a metal bonding layer, and then peeling off the composite substrate; grinding or etching down to the n-AlGaN layer, followed by selective etching on the n-AlGaN layer to form micro / nanopores; and depositing an N-electrode in the unetched n-AlGaN region. The fabrication method of the vertical-structure DUV LED device of this application can further improve the light extraction efficiency and luminous efficiency of the device, and also achieve high-power emission.

Description

Technical Field

[0001] This application relates to the field of semiconductor device technology, and more specifically, to a vertical structure deep ultraviolet LED device and its fabrication method. Background Technology

[0002] Compared to traditional deep ultraviolet light sources, deep ultraviolet light-emitting diodes (LEDs) based on group III-V nitride material systems have shown potential application value in fields such as photocuring, sterilization and disinfection, phototherapy, biomedical equipment, ultraviolet light communication, and full-spectrum lighting due to their advantages such as easy integration, high energy density, good stability, low power consumption, and long lifespan. They have already been widely used in some fields.

[0003] However, deep ultraviolet LED products still face serious problems, and related technologies need further improvement. Currently, the external quantum efficiency of deep ultraviolet (DUV) LED products is very low, generally not exceeding 10%, which is significantly lower than that of blue-green LED products. The main reasons for this are as follows: First, the epitaxial quality of DUV LEDs is not ideal, with high defect density leading to low internal quantum efficiency. Second, the significant difference in refractive index between AlGaN and air results in a very small light escape cone inside the chip, preventing most light from entering the escape cone and causing it to be continuously reflected internally and eventually absorbed by the material and converted into heat. Third, the use of a p-type doped GaN (p-GaN) layer as the ohmic contact layer, coupled with the strong absorption of deep ultraviolet light by p-GaN, leads to severe absorption of deep ultraviolet light. Fourth, as the Al content in the quantum well increases, the light emitted by DUV LEDs is predominantly transverse magnetic (TM) polar light with a propagation direction perpendicular to the C-axis. TM polar light falls outside the escape cone of the emitting surface, making it difficult to exit the LED device, and the extraction efficiency of TM polar light is only about one-tenth that of transverse electrical (TE) polar light. These are all pressing technical problems that need to be solved. Therefore, researchers have proposed various methods to improve light extraction efficiency, such as surface roughening structures, mesh-like P-type contact layer structures, and tilted sidewall structures. Utilizing photonic crystal structures to improve the light extraction efficiency of LED devices is another important method following these techniques. It mainly utilizes the photonic bandgap effect and diffraction of photonic crystal structures to improve the light extraction efficiency of the device. In addition, localized surface plasmons (LSPs) are also an effective way to improve the luminous efficiency of deep ultraviolet LEDs. When the distance between the metal particle and the active region of the LED is less than the penetration depth of the surface plasmons and their energies are matched, the electron-hole pairs in the active region will undergo LSP resonant coupling with the metal particle, resulting in energy transfer. This essentially provides an additional ultrafast recombination channel for the electron-hole pairs, thereby improving their luminous efficiency. At the same time, the presence of the metal particle also changes the light escape angle, thus improving the light extraction efficiency of the LED.

[0004] Currently, traditional deep ultraviolet (DUV) LEDs use sapphire substrates for growth. However, sapphire is an insulating material, and in most cases, its packaging is a flip-chip design, where both the N-electrode and P-electrode are fabricated on the same side of the chip. This packaging method has the following drawbacks: First, the poor thermal conductivity of the sapphire substrate limits the heat dissipation of the DUV LED device, affecting its lifespan. Second, the uneven lateral current flow in the N-type layer leads to current congestion, resulting in severe current pooling and reducing the LED's efficiency at high currents. Vertical LEDs promise to overcome the aforementioned problems on sapphire substrates. Due to their more direct layout, vertical LEDs have lower series resistance, which can reduce the turn-on voltage and thermal resistance. The reduced thermal resistance can alleviate the heat dissipation problem of vertical LEDs to some extent. Furthermore, the vertical current injection method allows for more uniform current distribution, avoiding localized heating that could degrade device performance. Therefore, compared to traditional flip-chip structures, vertical LEDs are an effective method for achieving high-power LED output. Currently, the most common method for fabricating vertical structures is laser lift-off to remove the sapphire substrate. However, during the fabrication process, due to the poor thermal conductivity of sapphire, the high-energy laser generates thermal shock upon irradiation of the sapphire substrate, resulting in numerous defects. This leads to decreased luminous efficiency and can even damage the epitaxial film, destroying the device and further hindering the development of deep ultraviolet LEDs. Therefore, a novel approach has emerged—electrochemical etching of the sacrificial layer. Its advantages include: no damage, selectability of the sacrificial layer location, and thus, diverse epitaxial layer designs.

[0005] In most literature on sacrificial layers in electrochemical corrosion, GaN is used as the sacrificial layer material. In this application, we use another material as the sacrificial layer—titanium nitride (TiN). TiN has a high melting point, high hardness, good chemical stability, and good electrical conductivity. It is a high-temperature resistant material and is therefore a suitable choice for the sacrificial layer. Summary of the Invention

[0006] The purpose of this application is to provide a vertical structure deep ultraviolet LED device and its fabrication method, which can not only further improve the light extraction efficiency and luminous efficiency of deep ultraviolet LED devices, but also achieve high-power emission.

[0007] One embodiment of this application provides a method for fabricating a vertical structure deep ultraviolet LED device, comprising: providing a composite substrate and forming a light-emitting epitaxial wafer on the composite substrate, the light-emitting epitaxial wafer comprising, sequentially disposed, an AlN layer, an undoped AlGaN (u-AlGaN) layer, an N-type doped AlGaN (n-AlGaN) layer, a deep ultraviolet multi-quantum-well layer, an electron blocking layer, a P-type doped AlGaN (p-AlGaN) layer, and a p-GaN layer; etching the light-emitting epitaxial wafer to form nanopores, forming a photonic crystal structure, depositing a first passivation layer within the nanopores using atomic deposition, and then forming a filling layer on the first passivation layer within the nanopores using electron beam lithography. Al metal particles are deposited in the nanopores. After depositing the Al metal particles, a passivation material is used to fill the nanopores. The passivation material encapsulates the Al metal particles. The Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material form a photonic crystal layer containing Al metal particles. A P electrode and an Al metal mirror are deposited on the photonic crystal layer containing Al metal particles. Then, they are connected to a conductive substrate through a metal bonding layer, and the composite substrate is peeled off. The side away from the conductive substrate is ground or etched until the n-AlGaN layer is reached. Then, selective etching is performed on the n-AlGaN layer to form micro- and nano-pores. An N electrode is deposited on the unetched n-AlGaN area, and the N electrode and the P electrode are located on opposite sides of the light-emitting epitaxial wafer.

[0008] As one feasible approach, an etched light-emitting epitaxial wafer is used to form nanopores, creating a photonic crystal structure. A first passivation layer is deposited within the nanopores using atomic deposition. Then, electron beam lithography is used to form filling holes and deposit Al metal particles on the first passivation layer within the nanopores. After depositing the Al metal particles, a passivation material is used to fill the nanopores, encapsulating the Al metal particles. The Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material together form a photonic crystal layer containing Al metal particles. This involves: etching multiple nanopores on one side of p-GaN using a nanosphere self-assembly method or nanoimprint lithography to form a photonic crystal structure, with the bottom of the nanopores extending to an electron blocking layer; depositing a first passivation layer within the nanopores using atomic deposition; then forming filling holes on the first passivation layer within the nanopores using electron beam lithography and depositing Al metal particles within the filling holes; and finally depositing a passivation material within the nanopores containing Al metal particles. The Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material together form a photonic crystal layer containing Al metal particles.

[0009] As a feasible approach, nanopores are arranged in an array to form a photonic crystal structure.

[0010] As one feasible approach, providing a composite substrate and forming a light-emitting epitaxial wafer on the composite substrate includes: a sapphire substrate; sputtering a release layer on the sapphire substrate, the release layer being made of titanium nitride material; and sputtering a layer of AlN material on the release layer. ； The sapphire substrate, release layer, and AlN material are subjected to high-temperature annealing, with the annealing temperature ranging from 1200℃ to 1700℃.

[0011] One feasible approach involves grinding or inductively coupled plasma etching down to the n-AlGaN layer, followed by selective etching on the n-AlGaN layer to form micro / nanopores. This includes: thinning the sapphire substrate and then using a laser to cut the thinned sapphire substrate with a mesh-like cutting path, exposing the release layer; using electrochemical etching to remove the release layer; grinding or inductively coupled plasma etching down to the n-AlGaN layer on the side away from the conductive substrate; and then selective etching on the n-AlGaN layer to form micro / nanopores.

[0012] As one feasible approach, a first passivation layer is deposited inside the nanopores using atomic deposition, followed by forming filling holes and depositing Al metal particles on the first passivation layer inside the nanopores using electron beam lithography. This includes: spin-coating a layer of photoresist onto the first passivation layer; forming multiple filling holes on the photoresist on the first passivation layer inside the nanopores using electron beam lithography, wherein the diameter of the filling holes is less than 50 nm; and depositing Al metal particles inside the filling holes so that the Al metal particles fill the filling holes.

[0013] As one feasible approach, providing a composite substrate and forming a light-emitting epitaxial wafer on the composite substrate includes: sequentially growing an AlN layer, a u-AlGaN layer, an n-AlGaN layer, a deep ultraviolet multi-quantum-well layer, an electron blocking layer, a p-AlGaN layer, and a p-GaN layer on the composite substrate.

[0014] One feasible approach involves depositing a P-electrode and an Al metal mirror on a photonic crystal layer containing Al metal particles, then connecting them to a conductive substrate via a metal bonding layer, and finally peeling off the composite substrate. This includes: removing the first passivation layer and passivation material on the p-GaN layer using photolithography and inductively coupled plasma etching until the p-GaN layer is exposed; depositing a P-electrode on the p-GaN layer; depositing an Al metal mirror on the P-electrode; connecting the Al metal mirror to the conductive substrate via a metal bonding layer; and peeling off the composite substrate.

[0015] As one possible approach, the material of the first passivation layer includes aluminum oxide (Al2O3) or silicon dioxide (SiO2).

[0016] As one feasible approach, an etched epitaxial wafer is used to form nanopores, creating a photonic crystal structure. A first passivation layer is deposited within the nanopores using atomic deposition. Then, electron beam lithography is used to form filling holes and deposit Al metal particles on the first passivation layer within the nanopores. After depositing the Al metal particles, a passivation material is used to fill the nanopores, encapsulating the Al metal particles. The Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material together form a photonic crystal layer containing Al metal particles. This includes depositing the passivation material using plasma-enhanced chemical vapor deposition, where the passivation material includes SiO2 or silicon nitride (SiO2). x N y ).

[0017] This application also provides a vertical structure deep ultraviolet LED device, which is fabricated using the above-described method for fabricating vertical structure deep ultraviolet LED devices.

[0018] The beneficial effects of the embodiments of this application include:

[0019] The vertical-structure deep ultraviolet LED device provided in this application uses TiN as a sacrificial layer to fabricate the vertical structure LED, avoiding the epitaxial wafer damage problems associated with laser-based vertical structure LED fabrication, thereby improving the LED yield. Furthermore, combining a photonic crystal layer containing Al metal particles with the vertical structure not only avoids the current congestion and poor heat dissipation issues associated with flip-chip structures, enabling high-power emission, but also further enhances the light extraction efficiency by utilizing the characteristics of the photonic crystal. Simultaneously, electron-hole pairs in the active region undergo LSP resonant coupling with the Al metal particles, thereby improving its luminous efficiency. Additionally, the reduction in p-GaN decreases light absorption, and the presence of Al metal particles alters the light escape angle, both contributing to improved light extraction efficiency. Therefore, the structure of this application further enhances the performance of the LED device. Attached Figure Description

[0020] To more clearly illustrate the technical solutions of the embodiments of this application, the accompanying drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this application and should not be regarded as a limitation of the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 One of the flowcharts for the fabrication method of the vertical structure deep ultraviolet LED device provided in the embodiments of this application;

[0022] Figure 2This is one of the state diagrams of a vertical structure deep ultraviolet LED device provided in an embodiment of this application;

[0023] Figure 3 This is the second state diagram of a vertical structure deep ultraviolet LED device provided in the embodiments of this application;

[0024] Figure 4 This is the third state diagram of a vertical deep ultraviolet LED device provided in the embodiments of this application;

[0025] Figure 5 This is the fourth state diagram of a vertical structure deep ultraviolet LED device provided in the embodiments of this application;

[0026] Figure 6 Fifth state diagram of a vertical structure deep ultraviolet LED device provided in the embodiments of this application;

[0027] Figure 7 This is the sixth state diagram of a vertical deep ultraviolet LED device provided in the embodiments of this application;

[0028] Figure 8 The seventh state diagram of a vertical structure deep ultraviolet LED device provided in the embodiments of this application;

[0029] Figure 9 This is the eighth state diagram of a vertical structure deep ultraviolet LED device provided in the embodiments of this application;

[0030] Figure 10 The second flowchart illustrates the fabrication method of the vertical structure deep ultraviolet LED device provided in the embodiments of this application.

[0031] Figure 11 The third flowchart illustrates the fabrication method of the vertical structure deep ultraviolet LED device provided in the embodiments of this application.

[0032] Icons: 11-Composite substrate; 111-Sapphire substrate; 112-Lifting layer; 113-AlN material; 12-Light-emitting epitaxial wafer; 121-u-AlGaN layer; 122-n-AlGaN layer; 123-Deep ultraviolet multi-quantum well layer; 124-Electron blocking layer; 125-p-AlGaN layer; 126-p-GaN layer; 127-AlN layer; 13-Nanopores; 131-Al metal particles; 132-First passivation layer; 133-Passivation material; 14-P electrode; 15-Al metal mirror; 16-Metal bonding layer; 17-Conductive substrate; 18-Micro / nanopores; 19-N electrode. Detailed Implementation

[0033] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. The components of the embodiments of this application described and shown in the accompanying drawings can generally be arranged and designed in various different configurations.

[0034] Therefore, the following detailed description of the embodiments of this application provided in the accompanying drawings is not intended to limit the scope of the claimed application, but merely to illustrate selected embodiments of the application. All other embodiments obtained by those skilled in the art based on the embodiments of this application without inventive effort are within the scope of protection of this application.

[0035] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0036] In the description of this application, it should be noted that the terms "center," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, or the orientation or positional relationship commonly used when the product is in use. They are used only for the convenience of describing this application and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on this application. Furthermore, the terms "first," "second," and "third," etc., are used only to distinguish descriptions and should not be construed as indicating or implying relative importance.

[0037] Furthermore, terms such as "horizontal" and "vertical" do not imply that components must be absolutely horizontal or suspended, but rather that they can be slightly tilted. For example, "horizontal" simply means that its direction is more horizontal than "vertical," and does not mean that the structure must be completely horizontal, but can be slightly tilted.

[0038] In the description of this application, it should also be noted that, unless otherwise expressly specified and limited, the terms "set up," "install," "connect," and "link" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in this application based on the specific circumstances.

[0039] This application provides a method for fabricating a vertically structured deep ultraviolet LED device, such as... Figure 1 As shown, it includes:

[0040] S10: As Figure 2 As shown, a composite substrate 11 is provided, and a light-emitting epitaxial wafer 12 is formed on the composite substrate 11. The light-emitting epitaxial wafer includes an AlN layer 127, a u-AlGaN layer 121, an n-AlGaN layer 122, a deep ultraviolet multi-quantum well layer 123, an electron blocking layer 124, a p-AlGaN layer 125, and a p-GaN layer 126 arranged sequentially.

[0041] S20: As Figure 3 , Figure 4 As shown, the light-emitting epitaxial wafer 12 is etched to form nanopores 13, and a first passivation layer 132 is deposited in the nanopores 13 by atomic deposition. Then, an electron beam exposure is used to form filling holes and deposit Al metal particles 131 on the first passivation layer 132 in the nanopores 13. After depositing Al metal particles 131, the nanopores 13 are filled with passivation material 133. The passivation material 133 encapsulates the Al metal particles 131. The Al metal particles 131, the photonic crystal structure, the first passivation layer 132, and the passivation material 133 form a photonic crystal layer containing Al metal particles 131.

[0042] S30: As Figure 5 As shown, the first passivation layer 132 and passivation material 133 on the photonic crystal layer containing Al metal particles 131, i.e., the first passivation layer 132 and passivation material 133 on the p-GaN layer 126, are removed by photolithography and inductively coupled plasma etching until the p-GaN layer 126 is exposed. Figure 6 As shown, a P electrode 14 and an Al metal mirror 15 are then deposited sequentially and connected to a conductive substrate 17 via a metal bonding layer 16.

[0043] S40: As Figure 7 As shown, the sapphire substrate 111 is thinned, and the thinned sapphire substrate 111 is cut using a laser with a grid-like cutting path, exposing the release layer 112. The release layer 112 is then removed using electrochemical etching. Grinding or inductively coupled plasma is then performed until the n-AlGaN layer 122 is reached. Afterwards, as... Figure 8 As shown, micro- and nano-pores 18 are formed by selective etching on the n-AlGaN layer 122;

[0044] S50: such as Figure 8 As shown, an N electrode 19 is deposited on the unetched n-AlGaN122 region, and the N electrode 19 and the P electrode 14 are located on opposite sides of the light-emitting epitaxial wafer 12.

[0045] In this embodiment, the N-electrode 19 and P-electrode 14 are respectively disposed on both sides of the light-emitting epitaxial wafer 12, making the deep ultraviolet LED device a vertical structure. Vertical structure optoelectronic devices have lower series resistance, thereby reducing the turn-on voltage and thermal resistance. The reduced thermal resistance can alleviate the heat dissipation problem of vertical structure optoelectronic devices to some extent. Secondly, the vertical current injection method allows for more uniform current distribution, avoiding localized heating and performance degradation. Therefore, compared to traditional flip-chip structures, vertical structure LEDs are an effective method for achieving high-power output in LED devices.

[0046] The vertical structure deep ultraviolet LED device provided in this application embodiment has an epitaxial wafer 12 etched with an array of nanopores 13 to form a photonic crystal structure. This photonic crystal structure can utilize the photonic bandgap effect and diffraction to improve the light extraction efficiency of the device. Furthermore, the electron-hole pairs in the active region (deep ultraviolet multi-quantum well layer 123) of the epitaxial wafer 12 undergo LSP resonant coupling with Al metal particles 131, thereby improving its luminous efficiency. Simultaneously, the presence of Al metal particles 131 also alters the light escape angle, further enhancing the LED's light extraction efficiency. Therefore, the deep ultraviolet LED device provided in this application can further improve both the light extraction efficiency and luminous efficiency of ultraviolet LEDs.

[0047] Optional, such as Figure 10 As shown, the etched epitaxial wafer 12 is etched into nanopores 13 to form a photonic crystal structure. A first passivation layer 132 is deposited within the nanopores using atomic deposition. Then, electron beam lithography is used to form filling holes and deposit Al metal particles 131 on the first passivation layer 132 within the nanopores 13. After depositing the Al metal particles 131, a passivation material 133 is used to fill the nanopores 13. The passivation material 133 encapsulates the Al metal particles 131. The Al metal particles 131, the photonic crystal structure, the first passivation layer 132, and the passivation material 133 form a photonic crystal layer containing Al metal particles, including:

[0048] S21: As Figure 3 As shown, multiple nanopores 13 are formed on one side of the p-GaN layer 126 by nanosphere self-assembly or nanoimprint lithography to form a photonic crystal structure. The bottom of the nanopores extends to the electron blocking layer 124. The light-emitting epitaxial wafer 12 includes an AlN layer 127, a u-AlGaN layer 121, an n-AlGaN layer 122, a deep ultraviolet multi-quantum well layer 123, an electron blocking layer 124, a p-AlGaN layer 125, and a p-GaN layer 126 grown on the composite substrate 11.

[0049] It should be understood that those skilled in the art can also use other nanoscale photolithography methods to etch nanopores, as long as multiple arrayed nanopores 13 can be etched on the p-GaN layer 126, p-AlGaN layer 125 and electron blocking layer to form a photonic crystal.

[0050] The nanopores are etched down to the electron blocking layer 124, and the distance between the bottom of the nanopores and the deep ultraviolet multi-quantum well layer 123 is between 2 nm and 40 mm.

[0051] S22: As Figure 4 As shown, a first passivation layer 132 is deposited in the nanopore 13, and then an electron beam exposure is used to form a filling hole and deposit Al metal particles 131 on the first passivation layer 132 in the nanopore 13.

[0052] S23: As Figure 4 As shown, a passivation material 133 is deposited in the nanopores 13 containing Al metal particles 131 to fill the nanopores 13. The passivation material 133 encapsulates the Al metal particles 131. The Al metal particles 131, the photonic crystal structure, the first passivation layer 132, and the passivation material 133 form a photonic crystal layer containing Al metal particles.

[0053] In one possible implementation of this application embodiment, the nanopores 13 are arranged in an array.

[0054] The photonic crystal has a period of 100nm to 400nm, and is etched up to the electron blocking layer 124 and up to 2nm to 40nm away from the deep ultraviolet multi-quantum well layer 123.

[0055] In addition, the etching of the p-GaN layer 126 forms nanopores 13, thereby reducing the material of the p-GaN layer 126. The reduction of the p-GaN layer 126 leads to a reduction in light absorption, thereby improving its light extraction efficiency.

[0056] Optionally, a composite substrate 11 is provided, and a light-emitting epitaxial wafer 12 is formed on the composite substrate 11, including:

[0057] S11: A sapphire substrate 111 is provided, and a release layer 112 is sputtered on the sapphire substrate 111. The release layer 112 is made of TiN material.

[0058] Specifically, a release layer 112 is sputtered on a sapphire substrate 111 at a sputtering temperature between 25°C and 600°C and a sputtering thickness between 5nm and 200nm.

[0059] The release layer 112 is made of TiN material. Titanium nitride has a high melting point, high hardness, good chemical stability, and good electrical conductivity. It is a high-temperature resistant material and is therefore a suitable choice as a sacrificial layer.

[0060] S12: A layer of AlN material 113 is sputtered onto the release layer;

[0061] Specifically, an AlN material 113 is sputtered onto the release layer at a temperature between 25°C and 600°C, with a sputtering thickness between 20 nm and 600 nm.

[0062] S13: The sapphire substrate 111, the release layer 112 and the AlN material 113 are subjected to high-temperature annealing treatment, wherein the annealing temperature is between 1200℃ and 1700℃.

[0063] Annealing allows AlN material 113 to recrystallize, improving crystal quality and thus providing a good template for the subsequent growth of the light-emitting epitaxial wafer 12.

[0064] In one possible implementation of the embodiments of this application, such as Figure 11 As shown, grinding or inductively coupled plasma etching is performed until the n-AlGaN layer 122 is reached, followed by selective etching on the n-AlGaN layer 122 to form micro / nanopores 18, including:

[0065] S41: Thin the sapphire substrate 111, wherein the thickness of the sapphire substrate 111 is reduced to 70μm to 100μm, and the thinned sapphire substrate 111 is cut by laser, with the cutting trajectory being a grid structure, so that the release layer 112 is exposed.

[0066] S42: The stripping layer 112 is removed by electrochemical corrosion.

[0067] S43: Grinding or inductively coupled plasma etching until the n-AlGaN layer 122 is reached;

[0068] S44: Selective etching is performed on the n-AlGaN layer 122 to form micro- and nano-pores 18.

[0069] Optionally, a first passivation layer 132 is deposited within the nanopores 13 using atomic deposition, followed by the formation of filling pores and deposition of Al metal particles 131 on the first passivation layer 132 within the nanopores 13 using electron beam lithography, including:

[0070] S221: A first passivation layer 132 is deposited inside the nanopores 13, and the thickness of the first passivation layer is 2nm to 10nm;

[0071] S222: Spin-coat a layer of photoresist onto the first passivation layer 132;

[0072] S223: Multiple filling holes are formed on the photoresist inside the nanopore 13 by electron beam exposure on the first passivation layer 132 inside the nanopore 13, wherein the diameter of the filling hole is less than 50nm.

[0073] Because the diameter of the filling holes is small, traditional photolithography techniques cannot meet the requirements for high-precision filling hole lithography. This application employs electron beam lithography, which offers higher photolithographic precision. The diameter of the filling holes is equal to the diameter of the Al metal particles 131, thus ensuring a small diameter for the Al metal particles 131.

[0074] S224: Deposit Al metal particles 131 in the filling holes so that the Al metal particles 131 fill the filling holes.

[0075] In one possible implementation of this application embodiment, providing a composite substrate 11 and forming a light-emitting epitaxial wafer 12 on the composite substrate 11 includes:

[0076] AlN layer 127, u-AlGaN layer 121, n-AlGaN layer 122, deep ultraviolet multi-quantum well layer 123, electron blocking layer 124, p-AlGaN layer 125 and p-GaN layer 126 grown on the composite substrate.

[0077] Specifically, an AlN layer 127 with a thickness of 0.2 μm to 10 μm is grown on the composite substrate 11. ， A u-AlGaN layer 121 with a thickness of 0.2 μm to 10 μm is then grown on the AlN layer 127. An n-AlGaN layer 122 with a thickness of 0.2 μm to 10 μm is then grown on the u-AlGaN layer 121. A deep ultraviolet multi-quantum well layer 123 is then grown on the n-AlGaN layer 122. An electron blocking layer 124 with a thickness of 5 nm to 200 nm is then grown on the deep ultraviolet multi-quantum well layer 123. A p-AlGaN layer 125 with a thickness of 10 nm to 300 nm is then grown on the electron blocking layer 124. Finally, a p-GaN layer 126 with a thickness of 10 nm to 300 nm is grown on the p-AlGaN layer 125. The p-GaN layer 126 can form an ohmic contact with the P electrode 14, reducing the turn-on voltage and heat generation.

[0078] Optional, such as Figure 5 , Figure 6As shown, the first passivation layer 132 and passivation material 133 on the epitaxial wafer containing the photonic crystal layer 131, i.e., the first passivation layer 132 and passivation material 133 on the p-GaN layer 126, are removed by photolithography and inductively coupled plasma etching until the p-GaN layer 126 is exposed. Then, a P electrode 14 and an Al metal mirror 15 are sequentially deposited and connected to the conductive substrate 17 through the metal bonding layer 16.

[0079] S31: As Figure 5 As shown, the first passivation layer 132 and passivation material 133 on the epitaxial wafer containing Al metal particles 131, i.e. the first passivation layer 132 and passivation material 133 on the p-GaN layer 126, are removed by photolithography and inductively coupled plasma etching until the p-GaN layer 126 is exposed.

[0080] S32: As Figure 6 As shown, P electrode 14 is deposited;

[0081] S33: Deposit Al metal mirror 15 on P electrode 14;

[0082] S34: The Al metal mirror 15 is connected to the conductive substrate 17 via the metal bonding layer 16.

[0083] As one possible approach, the material of the first passivation layer 132 includes Al2O3 or SiO2.

[0084] Optionally, etching the light-emitting epitaxial wafer forms nanopores 13, forming a photonic crystal structure. A first passivation layer 132 is deposited within the nanopores 13 using atomic deposition. Then, electron beam lithography is used to form filling holes on the first passivation layer 132 within the nanopores 13, and Al metal particles 131 are deposited. After depositing the Al metal particles 131, a passivation material 133 is used to fill the nanopores. The passivation material 133 encapsulates the Al metal particles 131. The formation of a photonic crystal layer containing Al metal particles 131 by the Al metal particles 131, the photonic crystal structure, the first passivation layer 132, and the passivation material 133 includes: depositing the passivation material 133 using plasma-enhanced chemical vapor deposition. The passivation material 133 includes SiO2 or Si. x N y .

[0085] This application also provides a vertically structured deep ultraviolet LED device, such as... Figure 8 , Figure 9As shown, the vertical structure deep ultraviolet LED device is fabricated using the above-described method. This vertical structure deep ultraviolet LED device has the same beneficial effects as the vertical structure deep ultraviolet LED device fabrication method in the foregoing embodiments. The fabrication method and beneficial effects of the vertical structure deep ultraviolet LED device have been described in detail in the foregoing embodiments and will not be repeated here.

[0086] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Various modifications and variations can be made to this application by those skilled in the art. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A method for fabricating a vertically structured deep ultraviolet LED device, characterized in that, include: A composite substrate is provided, and a light-emitting epitaxial wafer is formed on the composite substrate. The light-emitting epitaxial wafer includes an AlN layer, an undoped AlGaN layer, an N-type doped AlGaN layer, a deep ultraviolet multiple quantum well layer, an electron blocking layer, a P-type doped AlGaN layer, and a P-type doped GaN layer arranged sequentially. Etching the light-emitting epitaxial wafer forms nanopores, forming a photonic crystal structure. A first passivation layer is deposited in the nanopores using atomic deposition. Then, electron beam exposure is used to form filling holes and deposit Al metal particles on the first passivation layer in the nanopores. After depositing Al metal particles, a passivation material is used to fill the nanopores. The passivation material encapsulates the Al metal particles, and the Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material form a photonic crystal layer containing Al metal particles. A P-electrode and an Al metal mirror are deposited on the photonic crystal layer containing Al metal particles, and then connected to a conductive substrate through a metal bonding layer, and the composite substrate is peeled off. The side away from the conductive substrate is ground or inductively coupled plasma etched until the N-type doped AlGaN layer is formed. Then, selective etching is performed on the N-type doped AlGaN layer to form micro- and nano-pores. An N-electrode is deposited on a region of the unetched N-type doped AlGaN layer, with the N-electrode and the P-electrode located on opposite sides of the light-emitting epitaxial wafer.

2. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 1, characterized in that, The etched light-emitting epitaxial wafer forms nanopores, forming a photonic crystal structure. A first passivation layer is deposited in the nanopores using atomic deposition. Then, electron beam exposure is used to form filling holes and deposit Al metal particles on the first passivation layer in the nanopores. After depositing Al metal particles, a passivation material is used to fill the nanopores. The passivation material encapsulates the Al metal particles. The Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material form a photonic crystal layer containing Al metal particles, comprising: Multiple nanopores are formed on one side of the P-type doped GaN layer by nanosphere self-assembly or nanoimprint lithography to form a photonic crystal structure, and the bottom of the nanopores extends to the electron blocking layer. The first passivation layer is deposited in the nanopores by atomic deposition, and then a filling hole is formed on the first passivation layer in the nanopores by electron beam exposure, and Al metal particles are deposited in the filling hole. A passivation material is deposited within the nanopores containing the Al metal particles, wherein the Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material form the photonic crystal layer containing the Al metal particles.

3. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 2, characterized in that, The nanopores are arranged in an array.

4. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 2, characterized in that, The provision of a composite substrate and the formation of a light-emitting epitaxial wafer on the composite substrate include: A sapphire substrate, on which a release layer is sputtered, the release layer being made of titanium nitride material; AlN material is sputtered onto the release layer; The sapphire substrate, the release layer, and the AlN material are subjected to high-temperature annealing, wherein the annealing temperature is between 1200 and 1700°C.

5. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 4, characterized in that, The side furthest from the conductive substrate is ground or inductively coupled plasma etched until an N-type doped AlGaN layer is formed. Then, selected area etching is performed on the N-type doped AlGaN layer to form micro / nanopores, including: The sapphire substrate is thinned, and the thinned sapphire substrate is cut with a laser. The cutting trajectory is a grid structure, which exposes the release layer. The stripping layer is removed by electrochemical corrosion. Grinding or inductively coupled plasma etching is performed on one side of the conductive substrate until an N-type doped AlGaN layer is formed; Micro- and nano-pores were formed on an N-type doped AlGaN layer by selective etching using photolithography and inductively coupled plasma etching.

6. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 2, characterized in that, The process of depositing a first passivation layer within the nanopores using atomic deposition, followed by forming filling pores and depositing Al metal particles on the first passivation layer within the nanopores using electron beam lithography, includes: A layer of photoresist is spin-coated onto the first passivation layer; Multiple filling holes are formed on the photoresist on the first passivation layer inside the nanopore using electron beam lithography, wherein the diameter of the filling holes is less than 50 nm; Al metal particles are deposited in the filling holes so that the Al metal particles fill the filling holes.

7. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 1, characterized in that, The process of depositing a P-electrode and an Al metal mirror on the photonic crystal layer containing Al metal particles, then connecting them to a conductive substrate via a metal bonding layer, and finally peeling off the composite substrate includes: The first passivation layer and passivation material on the P-type doped GaN layer are removed by photolithography and inductively coupled plasma etching until the P-type doped GaN layer is exposed. Deposited P electrode; An Al metal mirror is deposited on the P electrode; The Al metal mirror is connected to the conductive substrate through the metal bonding layer; Peel off the composite substrate.

8. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 1, characterized in that, The material of the first passivation layer includes Al2O3 or SiO2.

9. The method for fabricating a vertical structure deep ultraviolet LED device according to claim 1, characterized in that, The etched light-emitting epitaxial wafer forms nanopores, forming a photonic crystal structure. A first passivation layer is deposited in the nanopores using atomic deposition. Then, electron beam exposure is used to form filling holes and deposit Al metal particles on the first passivation layer in the nanopores. After depositing Al metal particles, a passivation material is used to fill the nanopores. The passivation material encapsulates the Al metal particles. The Al metal particles, the photonic crystal structure, the first passivation layer, and the passivation material form a photonic crystal layer containing Al metal particles, comprising: The passivation material is deposited using plasma-enhanced chemical vapor deposition, and the passivation material includes SiO2 or Si. x N y .

10. A vertically structured deep ultraviolet LED device, characterized in that, It is prepared using the fabrication method of the vertical structure deep ultraviolet LED device according to any one of claims 1-9.

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