High-efficiency deep ultraviolet LED chip

Abstract

The invention belongs to the technical field of deep ultraviolet LED chips, and particularly relates to a high-efficiency deep ultraviolet LED chip which comprises an epitaxial wafer structure, etching regions, an N contact electrode, a P contact electrode, a thickened electrode, a passivation layer, a P thick gold layer and an N thick gold layer, the n etching regions are etched on the epitaxial wafer structure, the N contact electrode grows in the etching regions, and the N contact electrode grows in the N thick gold layer. The P contact electrode grows on the epitaxial wafer structure, a first thickened electrode and a second thickened electrode grow on the N contact electrode and the P contact electrode, the P thick gold layer and the N thick gold layer both grow on the passivation layer, the P thick gold layer is connected with the P contact electrode through the second thickened electrode, and the N thick gold layer is connected with the N contact electrode through the first thickened electrode. According to the invention, the n etching regions are etched on the N-type AlGaN composite structure layer, and the N contact electrodes are prepared in the etching regions, so that the uniform injection of current in the chip is realized, and the current injection efficiency is further improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of deep ultraviolet LED chips, and in particular relates to a high-efficiency deep ultraviolet LED chip. Background Art

[0002] In recent years, technological advances in the global LED industry have expanded the LED emission wavelength range from the visible light band to the ultraviolet and deep ultraviolet bands. Deep ultraviolet LEDs offer advantages such as high efficiency, long life, compact size, and environmental friendliness. They hold broad application prospects in water purification, air purification, ultraviolet communications, food processing and preservation, formaldehyde treatment, biochemical testing, and medical applications. However, existing deep ultraviolet LED chips suffer from low electro-optical conversion efficiency and short lifespan, hindering their widespread adoption.

[0003] The main reason is that the high-aluminum P-type AlGaN material in deep ultraviolet LED chips is difficult to dope, resulting in low chip luminescence efficiency. At the same time, the P-type AlGaN layer has a strong absorption effect on ultraviolet light, which reduces the chip's light extraction efficiency. In addition, the doping efficiency of the high-aluminum N-type AlGaN material is affected by the self-compensation of Si doping defects, resulting in high lateral resistance, further limiting current expansion. When the chip is injected with large currents, the uneven current distribution will be aggravated, causing current concentration, further limiting the chip's electro-optical conversion efficiency.

[0004] In existing technologies for p-type AlGaN layers, the growth conditions for the p-type GaN and n-type AlGaN layers, as well as the chip's N and P electrodes and annealing conditions, still need to be further optimized. Furthermore, the current density is higher in areas where the N and P electrodes are closer, while it is lower at the farther ends. This reduces the efficiency of current injection, leading to lower electro-optical conversion efficiency and a shorter lifespan. Therefore, it is necessary to further improve the uniformity of current distribution within the chip structure and optimize the electrode structure and electrical performance. Summary of the Invention

[0005] In response to the technical problems existing in existing deep ultraviolet LED chips, the present invention provides a high-efficiency deep ultraviolet LED chip.

[0006] In order to solve the above technical problems, the technical solution adopted by the present invention is: A high-efficiency deep ultraviolet LED chip, comprising an epitaxial wafer structure, an etching region, an N contact electrode, a P contact electrode, a first thickened electrode, a second thickened electrode, a passivation layer, a P thick gold layer, and an N thick gold layer, wherein n etching regions are provided, and the n etching regions are sequentially etched to the nth layer to the first layer of the N-type AlGaN composite structure layer of the epitaxial wafer structure, wherein the N-type AlGaN composite structure layer has n layers, which are sequentially the first layer to the nth layer from bottom to top, and n is a positive integer greater than 1; the N contact electrode is grown in the etching region, and the P contact electrode is grown on the epitaxial wafer. Structurally, a first thickened electrode is grown on the N contact electrode, and a second thickened electrode is grown on the P contact electrode. A passivation layer is grown on the epitaxial wafer structure, the first thickened electrode, and the second thickened electrode. The passivation layer has a connecting hole directly above the N contact electrode and the P contact electrode. The P thick gold layer is grown on the passivation layer above the P contact electrode, and the N thick gold layer is grown on the passivation layer above the N contact electrode. The P thick gold layer is connected to the P contact electrode through the second thickened electrode, and the N thick gold layer is connected to the N contact electrode through the first thickened electrode.

[0007] The epitaxial wafer structure includes a sapphire substrate, an AlN buffer layer, an N-type AlGaN composite structure layer, a quantum light-emitting layer, a P-type AlGaN layer and a P-GaN contact layer. The AlN buffer layer is grown on the sapphire substrate, the N-type AlGaN composite structure layer is grown on the AlN buffer layer, the quantum light-emitting layer is grown on the N-type AlGaN composite structure layer, the P-type AlGaN layer is grown on the quantum light-emitting layer, the P-GaN contact layer is grown on the P-type AlGaN layer, and the P contact electrode is grown on the P-GaN contact layer.

[0008] The etching area is etched from the P-GaN contact layer to the N-type AlGaN composite structure layer.

[0009] The etching area is etched to a position of 1 / 3-1 / 2 of the total thickness of a single layer of the N-type AlGaN composite structure layer.

[0010] The sheet resistance of the N-type AlGaN composite structure layer from the first layer to the nth layer increases layer by layer, decreases layer by layer, or first increases and then decreases, and the current lateral expansion capability decreases layer by layer, increases layer by layer, or first decreases and then increases.

[0011] A high-efficiency deep ultraviolet LED chip, wherein the preparation method of the chip comprises the following steps: S1. Growing an AlN buffer layer, an N-type AlGaN composite structure layer, a quantum light-emitting layer, a P-type AlGaN layer, and a P-GaN contact layer on a sapphire substrate in sequence from bottom to top to prepare an epitaxial wafer structure; S2. Using photolithography and dry etching processes, according to the designed area, n etching regions are respectively etched from the P-GaN contact layer, wherein the n etching regions are respectively etched to the nth layer to the first layer of the N-type AlGaN composite structure layer, and to a position of 1 / 3 to 1 / 2 of the total thickness of a single layer of the N-type AlGaN composite structure layer; S3, using photolithography, metal evaporation and high-temperature annealing processes to prepare N contact electrodes in n etched regions of the N-type AlGaN composite structure layer to form ohmic contacts; S4, using photolithography, metal evaporation and high temperature annealing processes to prepare a P contact electrode on the P-GaN contact layer; S5. Using photolithography and metal evaporation processes, prepare a first thickened electrode on the N contact electrode and prepare a second thickened electrode on the P contact electrode; S6. Using PECVD and photolithography processes, a passivation layer is formed on the epitaxial wafer structure, the first thickened electrode, and the second thickened electrode; S7, using photolithography, metal evaporation and metal lift-off processes to simultaneously form a P-thick gold layer and an N-thick gold layer on the passivation layer above the P-contact electrode and the N-contact electrode; S8. Use back-end substrate thinning and cutting processes to form independent unit chips.

[0012] The N contact electrode in S3 is made of one or more metal systems of Au, Cr, Ti, Al, Pt, and Ni. The annealing temperature of the N contact electrode is 700° C.-900° C., the annealing time is 60s-240s, and the annealing atmosphere is N2; The P contact electrode in S4 is made of one or more metal systems of Ni, Au, Pt, Rh or ITO material. The annealing temperature of the P contact electrode is 500°C-700°C, the annealing time is 60s-240s, and the annealing atmosphere is N2, Air or O2.

[0013] The first thickened electrode and the second thickened electrode in S5 are both made of one or more metal systems of Cr, Au, Pt, Ti, and Al, and the thickness of the first thickened electrode and the second thickened electrode are both 0.5 μm to 3 μm.

[0014] The passivation layer in S6 is made of SiO2 or Si3N4, and the thickness of the passivation layer is 0.5 μm-3 μm.

[0015] The P-thick gold layer and the N-thick gold layer in S7 are both made of Au / Sn alloy or Au / Sn superposition structure, and the thickness of the P-thick gold layer and the N-thick gold layer are both 2 μm-5 μm.

[0016] Compared with the prior art, the present invention has the following beneficial effects: 1. The present invention achieves uniform current injection in the chip by etching n etched regions on the N-type AlGaN composite structure layer and preparing N contact electrodes in each etched region, thereby further improving the current injection efficiency.

[0017] 2. The present invention designs an N-type AlGaN composite structure layer, whose sheet resistance increases layer by layer, decreases layer by layer, or first increases and then decreases, which is manifested as the lateral expansion capability of current decreases layer by layer, increases layer by layer, or first decreases and then increases, effectively optimizing the distribution of current in the chip, avoiding current concentration, and improving the electro-optical conversion efficiency.

[0018] 3. The present invention optimizes the design of the N-type AlGaN composite structure layer, optimizes current injection and distribution, and adopts a flip-chip structure, which effectively improves the electro-optical conversion efficiency of the deep ultraviolet LED chip and extends its service life. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] To more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for the embodiments or the description of the prior art. Obviously, the drawings described below are merely exemplary, and those skilled in the art can, without inventive effort, derive other implementation drawings based on the provided drawings.

[0020] The structures, proportions, sizes, etc. illustrated in this specification are intended solely to complement the contents disclosed herein and to facilitate understanding and reading by persons skilled in the art. They are not intended to limit the conditions under which the present invention may be implemented and therefore have no substantive technical significance. Any structural modifications, changes in proportions, or adjustments in sizes, without affecting the efficacy and objectives of the present invention, shall remain within the scope of the technical contents disclosed herein.

[0021] Figure 1 Schematic diagram of the epitaxial wafer structure of the present invention; Figure 2 Schematic cross-sectional view of the etching area of ​​the present invention; Figure 3 This is a schematic diagram of the chip structure of the present invention; Figure 4 A top view of the etched area in the chip structure of the present invention; Figure 5 is the light distribution diagram of the comparative example; Figure 6 This is the light distribution diagram of the experimental example.

[0022] Wherein: 101 is a sapphire substrate, 102 is an AlN buffer layer, 103 is an N-type AlGaN composite structure layer, 104 is a quantum light emitting layer, 105 is a P-type AlGaN layer, 106 is a P-GaN contact layer, 301 is an etching area, 401 is an N-type contact electrode, 402 is a P-type contact electrode, 4031 is a first thickened electrode, 4032 is a second thickened electrode, 404 is a passivation layer, 405 is a P-type gold layer, and 406 is an N-type gold layer. DETAILED DESCRIPTION

[0023] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only part of the embodiments of this application, not all the embodiments. These descriptions are only to further illustrate the features and advantages of the present invention, rather than to limit the claims of the present invention. Based on the embodiments in this application, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of this application.

[0024] The following embodiments of the present invention are described in further detail with reference to the accompanying drawings and examples. The following embodiments are used to illustrate the present invention but are not intended to limit the scope of the present invention.

[0025] In the description of this application, it should be noted that, unless otherwise expressly specified or limited, the terms "mounted," "connected," and "connected" should be understood in a broad sense. For example, they can refer to fixed, detachable, or integral connections; mechanical or electrical connections; direct or indirect connections through an intermediate medium; and internal communication between two components. Those skilled in the art will understand the specific meanings of the above terms in this application based on the specific circumstances.

[0026] Example 1

[0027] This embodiment provides a deep ultraviolet LED chip, such as Figure 1-4 As shown in FIG, the epitaxial wafer structure of the deep ultraviolet LED chip is composed of a sapphire substrate 101, an AlN buffer layer 102, an N-type AlGaN composite structure layer 103, a quantum light emitting layer 104, a P-type AlGaN layer 105 and a P-GaN contact layer 106 from bottom to top. The etched area 301 is etched from the P-GaN contact layer 106 to the N-type AlGaN composite structure layer 103. Figure 3As shown, the P contact electrode 402 is grown on the P-GaN contact layer 106, the first thickened electrode 4031 is grown on the N contact electrode 401, and the second thickened electrode 4032 is grown on the P contact electrode 402. A passivation layer 404 is grown on the P-GaN contact layer 106, the first thickened electrode 4031, and the second thickened electrode 4032. The passivation layer 404 has a connecting hole directly above the N contact electrode 401 and the P contact electrode 402. The P thick gold layer 405 and the N thick gold layer 406 are both grown on the passivation layer 404. The P thick gold layer 405 is connected to the P contact electrode 402 through the second thickened electrode 4032, and the N thick gold layer 406 is connected to the N contact electrode 401 through the first thickened electrode 4031.

[0028] Furthermore, the N-type AlGaN composite structure layer 103 is composed of n layers, which are sequentially arranged from the first layer to the nth layer from bottom to top. The sheet resistance of the N-type AlGaN composite structure layer 103 increases layer by layer, which is manifested as a layer-by-layer decrease in the lateral current expansion capability. For example, the sheet resistance of the first layer is 30Ω-39Ω, the sheet resistance of the second layer is 40Ω-49Ω, the sheet resistance of the third layer is 50Ω-59Ω, and so on.

[0029] The method for preparing the high-efficiency deep ultraviolet LED chip of this embodiment includes the following steps: Step 1: An AlN buffer layer 102, an N-type AlGaN composite structure layer 103, a quantum light emitting layer 104, a P-type AlGaN layer 105 and a P-GaN contact layer 106 are grown on a sapphire substrate 101 from bottom to top, thereby preparing an epitaxial wafer structure.

[0030] Step 2: Using the MESA photolithography process and the MESA-ICP dry etching process, n etching regions 301 are respectively etched from the P-GaN contact layer 106 according to the designed area. The n etching regions 301 are respectively etched to the nth layer to the 1st layer of the N-type AlGaN composite structure layer 103, and etched to 1 / 3 of the total thickness of the single layer of the N-type AlGaN composite structure layer 103.

[0031] Step 3: Using photolithography, metal evaporation and high-temperature annealing, N-type contact electrodes 401 are prepared in the n etched areas 301 of the N-type AlGaN composite structure layer 103 to form ohmic contacts. The N-type contact electrode 401 uses a Ti / Al / Ni / Au multilayer metal system. The annealing temperature is 800°C, the time is 120s, and the atmosphere is N2.

[0032] Step 4: Prepare the P contact electrode 402 by photolithography, metal evaporation and high temperature annealing. The P contact electrode 402 uses a Ni / Au multilayer metal system. The annealing temperature is 550° C., the time is 120 s, and the atmosphere is air.

[0033] Step 5: Use photolithography and metal evaporation to prepare the first thickened electrode 4031 and the second thickened electrode 4032, using a Ti / Pt / Au multilayer metal system with a total thickness of 1 μm.

[0034] Step 6: Use PECVD process and photolithography process to prepare passivation layer 404, the material of which is SiO2 with a thickness of 1 μm.

[0035] Step 7: Use photolithography, metal evaporation and metal stripping processes to simultaneously prepare a P-thick gold layer 405 and an N-thick gold layer 406, using an Au / Sn alloy structure with a total thickness of 3 μm.

[0036] Step 8: Use back-end substrate thinning and cutting processes to form independent unit chips.

[0037] Example 2

[0038] The N-type AlGaN composite structure layer 103 of this embodiment is composed of n layers. From bottom to top, the N-type AlGaN composite structure layer 103 is sequentially arranged from the first layer to the nth layer. The sheet resistance of the N-type AlGaN composite structure layer 103 decreases layer by layer, indicating a gradual increase in the lateral current spreading capability. For example, the sheet resistance of the first layer is 50Ω-59Ω, the sheet resistance of the second layer is 40Ω-49Ω, the sheet resistance of the third layer is 30Ω-39Ω, and the sheet resistance of the fourth layer is 20Ω-29Ω.

[0039] The method for preparing the high-efficiency deep ultraviolet LED chip of this embodiment includes the following steps: Step 1: An AlN buffer layer 102, an N-type AlGaN composite structure layer 103, a quantum light emitting layer 104, a P-type AlGaN layer 105 and a P-GaN contact layer 106 are grown sequentially on a sapphire substrate 101 from bottom to top, thereby preparing an epitaxial wafer structure.

[0040] Step 2: Using the MESA photolithography process and the MESA-ICP dry etching process, n etching regions 301 are respectively etched from the P-GaN contact layer 106 according to the designed area. The n etching regions 301 are respectively etched to the nth layer to the 1st layer of the N-type AlGaN composite structure layer 103, and etched to 1 / 2 of the total thickness of the single layer of the N-type AlGaN composite structure layer 103.

[0041] Step 3: Using photolithography, metal evaporation and high-temperature annealing, N contact electrodes 401 are prepared in the n etched areas 301 of the N-type AlGaN composite structure layer to form ohmic contacts. The N contact electrode 401 uses a Ti / Al / Ni / Au multilayer metal system, the annealing temperature is 850°C, the time is 150s, and the atmosphere is N2.

[0042] Step 4: Prepare the P contact electrode 402 by photolithography, metal evaporation and high temperature annealing. The electrode uses a Ni / Pt / Au multilayer metal system. The annealing temperature is 550° C., the time is 120 s, and the atmosphere is O 2 .

[0043] Step 5: Use photolithography and metal evaporation to prepare the first thickened electrode 4031 and the second thickened electrode 4032, using a Cr / Pt / Au multilayer metal system with a total thickness of 2 μm.

[0044] Step 6: Use PECVD process and photolithography process to prepare passivation layer 404, the material of which is Si3N4 with a thickness of 1.5μm.

[0045] Step 7: Use photolithography, metal evaporation and metal lift-off processes to simultaneously prepare a P-thick gold layer 405 and an N-thick gold layer 406, using an Au / Sn stacking structure with a total thickness of 4 μm.

[0046] Step 8: Use back-end substrate thinning and cutting processes to form independent unit chips.

[0047] Example 3

[0048] The N-type AlGaN composite structure layer 103 of this embodiment is composed of n layers, wherein the sheet resistance of the first to third layers increases layer by layer, and the sheet resistance of the fourth and fifth layers decreases layer by layer. For example, the sheet resistance of the first layer is 30Ω-39Ω, the sheet resistance of the second layer is 40Ω-49Ω, the sheet resistance of the third layer is 50Ω-59Ω, the sheet resistance of the fourth layer is 40Ω-59Ω, and the sheet resistance of the fifth layer is 30Ω-39Ω.

[0049] The method for preparing the high-efficiency deep ultraviolet LED chip of this embodiment includes the following steps: Step 1: An AlN buffer layer 102, an N-type AlGaN composite structure layer 103, a quantum light emitting layer 104, a P-type AlGaN layer 105 and a P-GaN contact layer 106 are grown sequentially on a sapphire substrate 101 from bottom to top, thereby preparing an epitaxial wafer structure.

[0050] Step 2: Using the MESA photolithography process and the MESA-ICP dry etching process, n etching regions 301 are etched from the P-GaN contact layer 106 according to the designed area. The n etching regions 301 are etched to the nth layer to the 1st layer of the N-type AlGaN composite structure layer 103, and are etched to 2 / 5 of the total thickness of the single layer.

[0051] Step 3: Using photolithography, metal evaporation and high-temperature annealing, N contact electrodes 401 are prepared on the n etched areas 301 of the N-type AlGaN composite structure layer 103 to form ohmic contacts. The electrodes are made of a Ti / Al / Pt / Au multilayer metal system. The annealing temperature is 850°C, the time is 180s, and the atmosphere is N2.

[0052] Step 4: Prepare the P contact electrode 402 by photolithography, metal evaporation and high temperature annealing. The P contact electrode 402 uses a Ni / Pt / Au multilayer metal system. The annealing temperature is 550° C., the time is 150 s, and the atmosphere is air.

[0053] Step 5: Use photolithography and metal evaporation to prepare the first thickened electrode 4031 and the second thickened electrode 4032, using a Ti / Pt / Au multilayer metal system with a total thickness of 1.5 μm.

[0054] Step 6: Prepare the passivation layer 404 by using PECVD process and photolithography process. The material is SiO2 with a thickness of 1.2 μm.

[0055] Step 7: Using photolithography, metal evaporation and metal lift-off processes, prepare the P-thick gold layer 405 and the N-thick gold layer 406 simultaneously, using an Au / Sn alloy structure with a total thickness of 3.5 μm.

[0056] Step 8: Use back-end substrate thinning and cutting processes to form independent unit chips.

[0057] Experimental comparison and effect verification To verify the beneficial effects of the high-efficiency deep ultraviolet LED chip provided by the present invention, comparative tests were conducted between a comparative example (a conventional structure chip) and three embodiments of the present invention (Experimental Example 1, Experimental Example 2, and Experimental Example 3), as follows: The comparative example (conventional structure chip) adopts the traditional deep ultraviolet LED chip structure, including a sapphire substrate, an AlN buffer layer, a single N-type AlGaN layer, a quantum light-emitting layer, a P-type AlGaN layer, and a P-GaN contact layer; only one etching area is set, and etching reaches the surface of the single N-type AlGaN layer; the N-contact electrode and the P-contact electrode are directly led out through the metal layer, and there is no layered N-type AlGaN composite structure layer, and the lateral current expansion capability is uniform and weak.

[0058] Experimental Example-1 is the chip of Example 1 of the present invention, Experimental Example-2 is the chip of Example 2 of the present invention, and Experimental Example-3 is the chip of Example 3 of the present invention.

[0059] Table 1 Comparison of chip performance parameters of the embodiment and the comparative example

[0060] The test results are shown in Table 1. The voltage (VF3) of the experimental example and the comparative example is basically the same, but the optical output power (LOP) is significantly improved: Experimental example-1 is about 29% higher than the comparative example, Experimental example-2 is about 38% higher, and Experimental example-3 is about 34% higher. Figure 5 、 Figure 6 As shown, combined with the microscopic light distribution characterization, the comparative example has obvious current crowding, while the experimental example has more uniform current distribution and more uniform light emission, which fully verifies that the present invention can effectively improve the electro-optical conversion efficiency and light emission uniformity of deep ultraviolet LED chips through multi-layer etching area design, N-type AlGaN composite structure layer optimization and electrode structure improvement.

[0061] The above only describes in detail the preferred embodiments of the present invention, but the present invention is not limited to the above embodiments. Various changes can be made within the knowledge of ordinary technicians in this field without departing from the purpose of the present invention, and various changes should be included in the scope of protection of the present invention.

Claims

1. A high-efficiency deep ultraviolet LED chip, characterized by: The invention comprises an epitaxial wafer structure, an etching region (301), an N contact electrode (401), a P contact electrode (402), a first thickened electrode (4031), a second thickened electrode (4032), a passivation layer (404), a P thick gold layer (405) and an N thick gold layer (406), wherein n etching regions (301) are provided, and the n etching regions (301) are sequentially etched to the nth layer to the first layer of the N-type AlGaN composite structure layer (103) of the epitaxial wafer structure, and the N-type AlGaN composite structure layer (103) is provided with n layers, which are sequentially the first layer to the nth layer from bottom to top, and n is a positive integer greater than 1; the N contact electrode (401) is grown in the etching region (301), the P contact electrode (402) is grown on the epitaxial wafer structure, and the first thickened electrode is grown on the N contact electrode (401). (4031), a second thickened electrode (4032) is grown on the P contact electrode (402), a passivation layer (404) is grown on the epitaxial wafer structure, the first thickened electrode (4031) and the second thickened electrode (4032), the passivation layer (404) is provided with a connecting hole directly above the N contact electrode (401) and the P contact electrode (402), the P thick gold layer (405) is grown on the passivation layer (404) above the P contact electrode (402), the N thick gold layer (406) is grown on the passivation layer (404) above the N contact electrode (401), the P thick gold layer (405) is connected to the P contact electrode (402) through the second thickened electrode (4032), and the N thick gold layer (406) is connected to the N contact electrode (401) through the first thickened electrode (4031).

2. The high-efficiency deep ultraviolet LED chip according to claim 1, characterized in that: The epitaxial wafer structure comprises a sapphire substrate (101), an AlN buffer layer (102), an N-type AlGaN composite structure layer (103), a quantum light-emitting layer (104), a P-type AlGaN layer (105), and a P-GaN contact layer (106); the AlN buffer layer (102) is grown on the sapphire substrate (101); the N-type AlGaN composite structure layer (103) is grown on the AlN buffer layer (102); the quantum light-emitting layer (104) is grown on the N-type AlGaN composite structure layer (103); the P-type AlGaN layer (105) is grown on the quantum light-emitting layer (104); the P-GaN contact layer (106) is grown on the P-type AlGaN layer (105); and the P contact electrode (402) is grown on the P-GaN contact layer (106).

3. The high-efficiency deep ultraviolet LED chip according to claim 2, characterized in that: The etching area (301) is etched from the P-GaN contact layer (106) to the N-type AlGaN composite structure layer (103).

4. The high-efficiency deep ultraviolet LED chip according to claim 3, characterized in that: The etching area (301) is etched to a position of 1 / 3-1 / 2 of the total thickness of a single layer of the N-type AlGaN composite structure layer (103).

5. The high-efficiency deep ultraviolet LED chip according to claim 4, characterized in that: The sheet resistance of the N-type AlGaN composite structure layer (103) from the first layer to the nth layer increases layer by layer, decreases layer by layer, or first increases and then decreases, and the current lateral expansion capability decreases layer by layer, increases layer by layer, or first decreases and then increases.

6. The high-efficiency deep ultraviolet LED chip according to claim 2, characterized in that: The chip preparation method comprises the following steps: S1, sequentially growing an AlN buffer layer (102), an N-type AlGaN composite structure layer (103), a quantum light-emitting layer (104), a P-type AlGaN layer (105), and a P-GaN contact layer (106) on a sapphire substrate (101) from bottom to top to obtain an epitaxial wafer structure; S2. Using photolithography and dry etching processes, n etching regions (301) are respectively etched from the P-GaN contact layer (106) according to the designed area, wherein the n etching regions (301) are respectively etched to the nth layer to the first layer of the N-type AlGaN composite structure layer (103), and to a position of 1 / 3 to 1 / 2 of the total thickness of a single layer of the N-type AlGaN composite structure layer (103); S3, using a photolithography process, metal evaporation and high-temperature annealing process to prepare N contact electrodes (401) in n etched regions (301) of the N-type AlGaN composite structure layer (103) to form ohmic contacts; S4, using photolithography, metal evaporation and high temperature annealing processes to prepare a P contact electrode (402) on the P-GaN contact layer (106); S5. Using photolithography and metal evaporation processes, prepare a first thickened electrode (4031) on the N contact electrode (401), and prepare a second thickened electrode (4032) on the P contact electrode (402); S6. Using PECVD and photolithography processes, a passivation layer (404) is prepared on the epitaxial wafer structure, the first thickened electrode (4031), and the second thickened electrode (4032); S7, using photolithography, metal evaporation and metal stripping processes to simultaneously prepare a P thick gold layer (405) and an N thick gold layer (406) on the passivation layer (404) above the P contact electrode (402) and the N contact electrode (401); S8. Use back-end substrate thinning and cutting processes to form independent unit chips.

7. The high-efficiency deep ultraviolet LED chip according to claim 6, characterized in that: The N contact electrode (401) in S3 is made of one or more metal systems of Au, Cr, Ti, Al, Pt, and Ni, and the annealing temperature of the N contact electrode (401) is 700° C.-900° C., the annealing time is 60s-240s, and the annealing atmosphere is N2; The P contact electrode (402) in S4 is made of one or more metal systems of Ni, Au, Pt, Rh or ITO material, the annealing temperature of the P contact electrode (402) is 500°C-700°C, the annealing time is 60s-240s, and the annealing atmosphere is N2, Air or O2.

8. The high-efficiency deep ultraviolet LED chip according to claim 6, characterized in that: The first thickened electrode (4031) and the second thickened electrode (4032) in S5 are both made of one or more metal systems of Cr, Au, Pt, Ti, and Al, and the thickness of the first thickened electrode (4031) and the second thickened electrode (4032) are both 0.5 μm-3 μm.

9. The high-efficiency deep ultraviolet LED chip according to claim 6, characterized in that: The passivation layer (404) in S6 is made of SiO2 or Si3N4, and the thickness of the passivation layer (404) is 0.5 μm-3 μm.

10. The high-efficiency deep ultraviolet LED chip according to claim 6, characterized in that: The P-thick gold layer (405) and the N-thick gold layer (406) in S7 both adopt an Au / Sn alloy or an Au / Sn superposition structure, and the thickness of the P-thick gold layer (405) and the N-thick gold layer (406) are both 2 μm-5 μm.

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