An AlGaN-based deep ultraviolet LED chip and its preparation method

Abstract

The present invention discloses an AlGaN-based deep ultraviolet LED chip and a preparation method thereof, relating to the field of semiconductor technology. The AlGaN-based deep ultraviolet LED chip includes an epitaxial wafer, and a p-type electrode and an n-type electrode disposed on the epitaxial wafer. The n-type electrode is provided with a stacked structure, comprising an ITO layer, a first Al layer, a first metal layer, a second Al layer, a second metal layer, and a third Al layer stacked in sequence on the n-type electrode. The ITO layer is composed of a plurality of ITO hemispheres arranged in an array, and the first Al layer fills the gaps between the plurality of ITO hemispheres arranged in an array. By providing the stacked structure on the n-type electrode, the arrayed ITO hemispheres in the stacked structure, and the stacked Al and metal layers, the present invention can effectively improve the current dispersion of the n-type electrode and reduce the light loss of the n-type electrode, thereby facilitating improved luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

Description

Technical Field

[0001] The present invention relates to the field of semiconductor technology, and in particular to an AlGaN-based deep ultraviolet LED chip and a preparation method thereof. Background Art

[0002] AlGaN-based deep ultraviolet LED chips refer to LED chips that use AlGaN materials as the light-emitting layer and can generate 260nm-285nm ultraviolet light waves. They have the advantages of being mercury-free, energy-saving, and environmentally friendly. They have important application markets in biomedicine, anti-counterfeiting identification, purification (water, air, etc.), etc.

[0003] However, during use, the existing AlGaN-based deep ultraviolet LED chips have problems such as high local current density and large light loss on their n-type electrodes, which seriously affect the luminous efficiency of the AlGaN-based deep ultraviolet LED chips. Summary of the Invention

[0004] The purpose of the present invention is to overcome the shortcomings of the existing technology. The present invention provides an AlGaN-based deep ultraviolet LED chip and a preparation method thereof. By arranging a stacked structure on an n-type electrode, an array of ITO hemispheres arranged in the stacked structure, and stacking Al layers and metal layers, the current dispersion of the n-type electrode can be effectively improved, and the light loss of the n-type electrode can be reduced, which is conducive to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0005] The present invention provides an AlGaN-based deep ultraviolet LED chip, comprising an epitaxial wafer, and a p-type electrode and an n-type electrode arranged on the epitaxial wafer. The n-type electrode is provided with a stacked structure, the stacked structure comprising an ITO layer, a first Al layer, a first metal layer, a second Al layer, a second metal layer and a third Al layer stacked in sequence on the n-type electrode; wherein the ITO layer is composed of a plurality of ITO hemispheres arranged in an array, and the first Al layer fills the gaps between the plurality of ITO hemispheres arranged in the array.

[0006] Specifically, the diameter of the ITO hemisphere ranges from 20 nm to 100 nm.

[0007] Specifically, the distance between adjacent ITO hemispheres ranges from 10 nm to 200 nm.

[0008] Specifically, the thickness of the first Al layer is in the range of 60 nm to 80 nm; the thickness of the second Al layer is in the range of 60 nm to 80 nm; and the thickness of the third Al layer is in the range of 80 nm to 100 nm.

[0009] Specifically, the thickness of the first metal layer is in the range of 2 nm to 4 nm.

[0010] Specifically, the thickness of the second metal layer is in the range of 2 nm to 4 nm.

[0011] Specifically, the material of the first metal layer is one of indium, lanthanum, rubidium, ruthenium, zinc, and rhodium.

[0012] Specifically, the material of the second metal layer is one of indium, lanthanum, rubidium, ruthenium, zinc, and rhodium.

[0013] The present invention also provides a method for preparing the AlGaN-based deep ultraviolet LED chip, comprising the following steps:

[0014] S1, preparing an epitaxial wafer with a p-type electrode and an n-type electrode;

[0015] S2, depositing an original ITO film layer on the n-type electrode;

[0016] S3, patterning the original ITO film layer to form a plurality of ITO hemispheres arranged in an array;

[0017] S4, depositing a first Al layer on the plurality of ITO hemispheres arranged in an array;

[0018] S5. Depositing a first metal layer on the first Al layer;

[0019] S6. Depositing a second Al layer on the first metal layer;

[0020] S7, depositing a second metal layer on the second Al layer;

[0021] S8. Deposit a third Al layer on the second metal layer.

[0022] Specifically, after step S8, the method further includes:

[0023] Under an inert atmosphere, the n-type electrode, the plurality of arrayed ITO hemispheres, the first Al layer, the first metal layer, the second Al layer, the second metal layer and the third Al layer are annealed; wherein the annealing temperature range is 300°C-600°C.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] In the AlGaN-based deep ultraviolet LED chip of the present invention, a stacked structure is provided on the n-type electrode, an ITO layer in the stacked structure is in direct contact with the n-type electrode, and the ITO layer is composed of a plurality of ITO hemispheres arranged in an array, and a first Al layer fills the gaps between the plurality of ITO hemispheres arranged in the array. Since the ITO material has good light transmittance and conductivity, the arrayed ITO hemispheres can promote the dispersion of current into the n-type electrode, directly improving the current dispersion of the n-type electrode and reducing light loss. Moreover, under the action of the ITO hemispheres, the side of the first Al layer in contact with the ITO layer forms an uneven rough surface, thereby obtaining a larger reflection area, which is conducive to reflecting back light emitted from the n-type electrode. At the same time, the tiny ITO hemispheres can form a microcavity to increase the light extraction effect. The Al element of the first Al layer adheres to the microcavity to form a metal structure of the microcavity, thereby forming a resonant cavity, which is conducive to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0026] The first Al layer, the first metal layer, the second Al layer, the second metal layer and the third Al layer in the stacked structure cooperate with each other to reduce light loss while reflecting back as much light emitted from the n-type electrode as possible, which is beneficial to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip; moreover, the stacked structure can provide good flatness, which is beneficial to maintaining good ohmic contact without losing the metal's reflectivity to light, which has a positive effect on the luminous efficiency of the AlGaN-based deep ultraviolet LED chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order 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 use in the embodiments or the description of the prior art. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0028] Figure 1 Schematic diagram of the structure of an AlGaN-based deep ultraviolet LED chip in an embodiment of the present invention;

[0029] Figure 2 is a schematic structural diagram of a laminated structure according to an embodiment of the present invention;

[0030] Figure 3 is a schematic diagram of the relevant structure of the n-type electrode in an embodiment of the present invention;

[0031] Figure 4 1 is a schematic flow chart of a method for preparing an AlGaN-based deep ultraviolet LED chip according to an embodiment of the present invention;

[0032] Figure 5Schematic diagram of the structure of an epitaxial wafer in an embodiment of the present invention;

[0033] Figure 6 Schematic diagram of the structure of preparing n-type mesas in an embodiment of the present invention;

[0034] Figure 7 Schematic diagram of the structure of an epitaxial wafer with a p-type electrode and an n-type electrode in an embodiment of the present invention;

[0035] Figure 8 This is a schematic diagram of the structure of preparing the original ITO film layer in an embodiment of the present invention;

[0036] Figure 9 This is a schematic diagram of the structure of preparing an ITO block in an embodiment of the present invention;

[0037] Figure 10 Schematic diagram of the structure of preparing ITO hemispheres in an embodiment of the present invention;

[0038] Figure 11 2 is a schematic diagram of the structure of preparing the first Al layer in an embodiment of the present invention;

[0039] Figure 12 is a schematic structural diagram of preparing a first metal layer in an embodiment of the present invention;

[0040] Figure 13 2 is a schematic diagram of the structure of preparing the second Al layer in an embodiment of the present invention;

[0041] Figure 14 is a schematic structural diagram of preparing the second metal layer in an embodiment of the present invention;

[0042] Figure 15 2 is a schematic diagram of the structure of preparing the third Al layer in an embodiment of the present invention;

[0043] Figure 16 Schematic diagram of the structure of preparing a passivation protective layer in an embodiment of the present invention;

[0044] Figure 17 It is a schematic diagram of the structure of preparing an n-type pad in an embodiment of the present invention.

[0045] In the accompanying drawings, 100, epitaxial wafer; 101, n-type mesa; 110, substrate; 120, AlN layer; 130, AlN / AlGaN stress buffer layer; 140, n-AlGaN layer; 150, multi-quantum well structure layer; 160, electron blocking layer; 170, p-AlGaN layer; 180, p-GaN layer; 200, p-type electrode; 300, n-type electrode; 400, stacked structure; 401, original ITO film layer; 402, ITO block; 410, ITO layer; 411, ITO hemisphere; 420, first Al layer; 430, first metal layer; 440, second Al layer; 450, second metal layer; 460, third Al layer; 500, passivation protection layer; 600, n-type pad. DETAILED DESCRIPTION

[0046] The following will clearly and completely describe the technical solutions in the embodiments of the present invention in conjunction with the accompanying drawings. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative efforts shall fall within the scope of protection of the present invention.

[0047] Example 1

[0048] The present invention provides an AlGaN-based deep ultraviolet LED chip. Figure 1 FIG2 shows a schematic structural diagram of an AlGaN-based deep ultraviolet LED chip according to an embodiment of the present invention. The AlGaN-based deep ultraviolet LED chip includes an epitaxial wafer 100, and a p-type electrode 200 and an n-type electrode 300 disposed on the epitaxial wafer 100. A stacked structure 400 is disposed on the n-type electrode 300. Figure 2 A schematic structural diagram of a stacked structure in an embodiment of the present invention is shown, wherein the stacked structure 400 includes an ITO layer 410, a first Al layer 420, a first metal layer 430, a second Al layer 440, a second metal layer 450, and a third Al layer 460 sequentially stacked on the n-type electrode 300; wherein the ITO layer 410 is composed of a plurality of ITO hemispheres 411 arranged in an array, and the first Al layer 420 fills the gaps between the plurality of ITO hemispheres 411 arranged in an array.

[0049] In the AlGaN-based deep ultraviolet LED chip of the present invention, since the ITO material has good light transmittance and conductivity, the arrayed ITO hemispheres 411 can promote the dispersion of current into the n-type electrode 300, directly improving the current dispersion of the n-type electrode 300 and reducing light loss. Moreover, under the action of the ITO hemispheres 411, the side of the first Al layer 420 in contact with the ITO layer 410 forms an uneven rough surface, thereby obtaining a larger reflection area, which is beneficial for reflecting back the light emitted from the n-type electrode 300. At the same time, the tiny ITO hemispheres 411 can form a microcavity to increase the light extraction effect. The Al element of the first Al layer 420 adheres to the microcavity to form a metal structure of the microcavity, thereby forming a resonant cavity, which is beneficial for improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0050] The first Al layer 420, the first metal layer 430, the second Al layer 440, the second metal layer 450 and the third Al layer 460 in the stacked structure 400 cooperate with each other to reduce light loss while reflecting back as much light emitted from the n-type electrode 300 as possible, which is beneficial to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip; moreover, the stacked structure 400 can provide good flatness, which is beneficial to maintaining good ohmic contact without losing the metal's reflectivity to light, which has a positive effect on the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0051] In some specific embodiments, the diameter of the ITO hemispheres 411 ranges from 20 nm to 100 nm, and the spacing between adjacent ITO hemispheres 411 ranges from 10 nm to 200 nm, making them easy to process and shape. The nanoscale ITO hemispheres 411 provide a large surface area, which not only facilitates uniform current distribution but also promotes interaction between light and matter. Preferably, the diameter of the ITO hemispheres 411 is 20 nm, and the spacing between adjacent ITO hemispheres 411 ranges from 200 nm.

[0052] In some specific embodiments, the thickness of the first Al layer 420 ranges from 60 nm to 80 nm (this thickness does not include the portion filling the gaps between the ITO hemispheres); the thickness of the second Al layer 440 ranges from 60 nm to 80 nm; and the thickness of the third Al layer 460 ranges from 80 nm to 100 nm. Each Al layer is used to reflect light emitted from the n-type electrode 300 and is relatively thin to reduce light absorption. The first Al layer 420 and the second Al layer 440 are of similar or equal thickness, while the third Al layer 460 is relatively thick, which facilitates step-by-step reflection of light and reduces light loss.

[0053] Preferably, the thickness of the first Al layer 420 is 60 nm, the thickness of the second Al layer 440 is 60 nm, and the thickness of the third Al layer 460 is in the range of 80 nm.

[0054] In some specific embodiments, the thickness of the first metal layer 430 is in the range of 2 nm to 4 nm, and the thickness of the second metal layer 450 is in the range of 2 nm to 4 nm. The material of the first metal layer 430 is one of indium, lanthanum, rubidium, ruthenium, zinc, and rhodium, and the material of the second metal layer 450 is one of indium, lanthanum, rubidium, ruthenium, zinc, and rhodium. Each metal layer is used to separate each Al layer, which can prevent Al electromigration and weaken the standing wave effect. Preferably, the thickness of the first metal layer 430 is 2 nm, the thickness of the second metal layer 450 is 2 nm, the material of the first metal layer 430 is indium, and the material of the second metal layer 450 is indium.

[0055] Figure 3 The schematic diagram of the structure of the n-type electrode in the embodiment of the present invention is shown. A passivation protection layer 500 is provided around the stacked structure 400. The passivation protection layer 500 also surrounds the n-type electrode 300, which can prevent Al electromigration and protect the stacked structure 400 and the n-type electrode 300 from oxidation. Specifically, the material of the passivation protection layer 500 is one or more of SiO2, SiNx, and SiOxNy. Furthermore, the thickness of the passivation protection layer 500 is in the range of

[0056] In some specific embodiments, see Figure 3 An n-type pad 600 is disposed at the upper end of the stacked structure 400. The n-type pad 600 is directly connected to the stacked structure 400. The n-type pad 600 has a relatively large surface area, facilitating the packaging and soldering of the AlGaN-based deep ultraviolet LED chip. Specifically, the material of the n-type pad 600 is one or more of Ni, Ti, Pt, and Au. Furthermore, the orthographic projection area of ​​the n-type pad 600 is at least 1.5 times the orthographic projection area of ​​the n-type electrode 300.

[0057] In some specific embodiments, see Figure 3 The orthographic projection area of ​​the stacked structure 400 is equal to the orthographic projection area of ​​the n-type electrode 300, which can ensure that the stacked structure 400 and the n-type electrode 300 are in full contact. On the one hand, it is beneficial to weaken the phenomenon of high local current density of the n-type electrode 300, and on the other hand, it is beneficial to reflect the light emitted from the n-type electrode 300 back and reduce light loss; it has a positive effect on improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0058] The AlGaN-based deep ultraviolet LED chip of the present invention can effectively improve the current dispersion of the n-type electrode 300 and reduce the loss of light by the n-type electrode 300 by providing a stacked structure 400 on the n-type electrode 300, an array of ITO hemispheres 411 arranged in the stacked structure 400, and a stacked Al layer and a metal layer, which is beneficial to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0059] Example 2

[0060] The present invention also provides a method for preparing the AlGaN-based deep ultraviolet LED chip. Figure 4 The flowchart of the method for preparing an AlGaN-based deep ultraviolet LED chip according to an embodiment of the present invention is shown. The method comprises the following steps:

[0061] S1, preparing an epitaxial wafer with a p-type electrode and an n-type electrode;

[0062] Figure 5 Schematic diagram of the structure of an epitaxial wafer in an embodiment of the present invention is shown. A substrate 110 is provided, and an AlN layer 120, an AlN / AlGaN stress buffer layer 130, an n-AlGaN layer 140, a multi-quantum well structure layer 150, an electron blocking layer 160, a p-AlGaN layer 170, and a p-GaN layer 180 are sequentially grown on the substrate 110.

[0063] Figure 6 Schematic diagram of the structure of preparing n-type mesas in an embodiment of the present invention is shown, wherein the predetermined area of ​​the p-GaN layer 180 is etched down to the n-AlGaN layer 140 to form an n-type mesa 101;

[0064] Figure 7 A schematic structural diagram of an epitaxial wafer with a p-type electrode and an n-type electrode in an embodiment of the present invention is shown. A p-type electrode 200 is deposited on the unetched p-GaN layer 180, and an n-type electrode 300 is deposited on the n-type mesa 101 to obtain an epitaxial wafer 100 with a p-type electrode 200 and an n-type electrode 300.

[0065] S2, depositing an original ITO film layer on the n-type electrode;

[0066] Figure 8 The schematic diagram of the structure of preparing the original ITO film layer in the embodiment of the present invention is shown. The original ITO film layer 401 is deposited on the n-type electrode 300 by magnetron sputtering. The thickness of the original ITO film layer 401 is in the range of 50nm-130nm.

[0067] Specifically, the epitaxial wafer 100 with the p-type electrode 200 and the n-type electrode 300 is placed in a vacuum chamber at a vacuum degree of 4.5×10-4 Pa-5.5×10 -4 The original ITO film layer 401 is grown under the conditions of 0.5 nm / s-0.8 nm / s, argon flow rate of 20 L / min-30 L / min, power of 40 W-50 W, sputtering rate of 0.5 nm / s-0.8 nm / s and temperature of 400 ° C-500 ° C; the obtained original ITO film layer 401 has a dense texture and good adhesion to the n-type electrode 300, laying the foundation for the subsequent formation of the ITO hemisphere 411.

[0068] Furthermore, by mass fraction, using 10%-15% SnO2 and 85%-90% In2O3 as target sources can improve the carrier concentration and mobility of the original ITO film layer 401, thereby having a positive effect on the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0069] S3, patterning the original ITO film layer to form a plurality of ITO hemispheres arranged in an array;

[0070] Figure 9 A schematic diagram of the structure of preparing ITO blocks in an embodiment of the present invention is shown. Using a photoresist as a mask, the original ITO film layer 401 is etched with argon plasma to form a plurality of ITO blocks 402 arranged in an array. Figure 10 A schematic diagram of the structure for preparing ITO hemispheres in an embodiment of the present invention is shown. Argon plasma is then used to bombard the array of ITO blocks 402, forming an array of ITO hemispheres 411. The resulting ITO hemispheres 411 have a well-defined spherical morphology. Because ITO material has excellent light transmittance and conductivity, the array of ITO hemispheres 411 promotes current dispersion into the n-type electrode 300, directly improving the current dispersion of the n-type electrode 300 while minimizing light loss.

[0071] In some specific embodiments, Cr elements are injected into the plurality of ITO hemispheres 411 arranged in an array, and the injection concentration of Cr elements ranges from 1.1E18 cm -3 to 1.5E19cm -3 The injection energy is between 0.1keV and 0.2keV, and the average distribution depth of the Cr element is 1.5nm-2.0nm, which can enhance the microcavity effect of the ITO hemisphere 411, thereby improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0072] In some specific embodiments, the diameter of the ITO hemispheres 411 ranges from 20 nm to 100 nm, and the spacing between adjacent ITO hemispheres 411 ranges from 10 nm to 200 nm, making them easy to process and form. The nanoscale nature of the ITO hemispheres 411 provides a large surface area, which not only facilitates uniform current distribution but also promotes interaction between light and matter.

[0073] S4, depositing a first Al layer on the plurality of ITO hemispheres arranged in an array;

[0074] Figure 11 The schematic diagram of the structure of the preparation of the first Al layer in the embodiment of the present invention is shown. The first Al layer 420 is deposited on the plurality of ITO hemispheres 411 arranged in an array by magnetron sputtering. It is not easy to damage the surface of the ITO hemispheres 411, and the gaps between the ITO hemispheres 411 can be fully filled. Specifically, the thickness of the first Al layer 420 ranges from 60nm to 80nm (this thickness does not include the portion filling the gaps between the ITO hemispheres). Under the action of the ITO hemispheres 411 arranged in the array, the side of the first Al layer 420 in contact with the ITO hemispheres 411 forms an uneven rough surface, obtaining a larger reflection area, which is conducive to reflecting back the light emitted from the n-type electrode 300; at the same time, the tiny ITO hemispheres 411 can form a microcavity to increase the light output effect. The Al element of the first Al layer 420 adheres to the microcavity to form a metal structure of the microcavity, thereby forming a resonant cavity, which is conducive to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0075] Furthermore, at a vacuum degree of 4.5×10 -4 Pa-5.5×10 -4 Under the conditions of Pa, argon flow rate 30L / min-40L / min, power 60W-70W, sputtering rate 0.1nm / s-0.3nm / s and temperature 100℃-200℃, the first Al layer 420 is grown. The obtained first Al layer 420 is smooth, dense and has good light reflectivity.

[0076] S5. Depositing a first metal layer on the first Al layer;

[0077] Figure 12 A schematic diagram of the structure for preparing a first metal layer in an embodiment of the present invention is shown. A first metal layer 430 is deposited on the first Al layer 420 using magnetron sputtering. The thickness of the first metal layer 430 ranges from 2 nm to 4 nm, and the material of the first metal layer 430 is one of indium, lanthanum, rubidium, ruthenium, zinc, and rhodium. The first metal layer 430 serves to separate the first Al layer 420 from the subsequent second Al layer 440, preventing Al electromigration and reducing the standing wave effect.

[0078] Specifically, at a vacuum degree of 4.5×10 -4 Pa-5.5×10 -4 The first metal layer 430 is grown under the conditions of 0.01 nm / s-0.02 nm / s, argon flow rate of 10 L / min-15 L / min, power of 20 W-30 W, sputtering rate of 0.01 nm / s-0.02 nm / s and temperature of 100 ° C-200 ° C, which is gentle and controllable, and helps to avoid damaging the first Al layer 420.

[0079] S6. Depositing a second Al layer on the first metal layer;

[0080] Figure 13 A schematic structural diagram of preparing the second Al layer in an embodiment of the present invention is shown. The second Al layer 440 is deposited on the first metal layer 430 by magnetron sputtering. The thickness of the second Al layer 440 is in the range of 60nm-80nm.

[0081] Specifically, at a vacuum degree of 4.5×10 -4 Pa-5.5×10 -4 Under the conditions of Pa, argon flow rate 30L / min-40L / min, power 60W-70W, sputtering rate 0.1nm / s-0.3nm / s and temperature 100℃-200℃, the second Al layer 440 is grown. The obtained second Al layer 440 is smooth, dense and has good light reflectivity.

[0082] S7, depositing a second metal layer on the second Al layer;

[0083] Figure 14 A schematic diagram of the structure for preparing a second metal layer according to an embodiment of the present invention is shown. A second metal layer 450 is deposited on the second Al layer 440 using magnetron sputtering. The thickness of the second metal layer 450 ranges from 2 nm to 4 nm, and the material of the second metal layer 450 is one of indium, lanthanum, rubidium, ruthenium, zinc, and rhodium. The second metal layer 450 serves to separate the second Al layer 440 from the subsequent third Al layer 460, preventing Al electromigration and reducing the standing wave effect.

[0084] Specifically, at a vacuum degree of 4.5×10 -4 Pa-5.5×10 -4 Under the conditions of 0.05 nm Pa, argon flow rate of 10 L / min-15 L / min, power of 20 W-30 W, sputtering rate of 0.01 nm / s-0.02 nm / s and temperature of 100 ° C-200 ° C, the second metal layer 450 is grown in a gentle and controllable manner, which is beneficial to avoid damaging the second Al layer 440.

[0085] S8, depositing a third Al layer on the second metal layer;

[0086] Figure 15 A schematic structural diagram of preparing the third Al layer in an embodiment of the present invention is shown. The third Al layer 460 is deposited on the second metal layer 450 by magnetron sputtering. The thickness of the third Al layer 460 is in the range of 80 nm to 100 nm.

[0087] Specifically, at a vacuum degree of 4.5×10 -4 Pa-5.5×10 -4 Under the conditions of Pa, argon flow rate 30L / min-40L / min, power 60W-70W, sputtering rate 0.1nm / s-0.3nm / s and temperature 100℃-200℃, the third Al layer 460 is grown. The obtained third Al layer 460 is smooth, dense and has good light reflectivity.

[0088] The array-arranged ITO hemispheres 411, the first Al layer 420, the first metal layer 430, the second Al layer 440, the second metal layer 450 and the third Al layer 460 constitute a stacked structure 400. The stacked structure 400 can reduce light loss while reflecting back as much light as possible emitted from the n-type electrode 300, which is beneficial to improving the luminous efficiency of the AlGaN-based deep ultraviolet LED chip; moreover, the stacked structure 400 can provide good flatness, which is beneficial to maintaining good ohmic contact, while not losing the metal's reflectivity to light, which has a positive effect on the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0089] In some specific embodiments, after step S8, the method further includes:

[0090] Under an inert atmosphere, the n-type electrode 300, the plurality of arrayed ITO hemispheres 411, the first Al layer 420, the first metal layer 430, the second Al layer 440, the second metal layer 450 and the third Al layer 460 are annealed; wherein the annealing temperature range is 300°C-600°C.

[0091] During the formation of the n-type electrode 300 and the stacked structure 400, impurities are inevitably present, which can affect the performance and reliability of the AlGaN-based deep-ultraviolet LED chip. Annealing heats the n-type electrode 300 and the stacked structure 400, removing some of these impurities and improving the quality of the AlGaN-based deep-ultraviolet LED chip. Furthermore, annealing improves the crystal structure of the n-type electrode 300 and the stacked structure 400, repairing some crystal defects (such as holes and oxygen vacancies), thereby enhancing the performance and stability of the AlGaN-based deep-ultraviolet LED chip.

[0092] In addition, the stacked structure 400 can reduce the temperature required for the annealing process, which is beneficial to saving energy and protecting the AlGaN-based deep ultraviolet LED chip from high temperature damage; the stacked structure 400 can maintain good flatness during the annealing process, which is beneficial to maintaining good ohmic contact, while not losing the metal's reflectivity to light, which has a positive effect on the luminous efficiency of the AlGaN-based deep ultraviolet LED chip.

[0093] Figure 16 The schematic diagram of the structure of preparing the passivation protection layer in an embodiment of the present invention is shown, and after step S8, the following steps are further included:

[0094] A passivation protection layer 500 is deposited along the surface of the n-type electrode 300 and the stacked structure 400; the material of the passivation protection layer 500 is one or more of SiO2, SiNx, and SiOxNy, and the thickness of the passivation protection layer 500 is in the range of This can prevent Al electromigration and protect the stacked structure 400 and the n-type electrode 300 from being oxidized.

[0095] Figure 17 A schematic diagram of the structure for preparing an n-type pad in an embodiment of the present invention is shown. A portion of the passivation layer 500 at the top of the stacked structure 400 is etched away, and then an n-type pad 600 is deposited on the stacked structure 400 using a technique such as magnetron sputtering or electron beam evaporation. The n-type pad 600 passes through the passivation layer 500 and directly connects to the stacked structure 400. The n-type pad 600 has a relatively large surface area, facilitating the packaging and soldering of AlGaN-based deep ultraviolet LED chips. The material of the n-type pad 600 is one or more of Ni, Ti, Pt, and Au. The orthographic projection area of ​​the n-type pad 600 is at least 1.5 times the orthographic projection area of ​​the n-type electrode 300.

[0096] The present invention's method for fabricating an AlGaN-based deep-ultraviolet LED chip involves forming a stacked structure 400 on an n-type electrode 300 and performing an annealing process. First, the stacked structure 400 minimizes light loss while reflecting as much light as possible from the n-type electrode 300, thereby improving the luminous efficiency of the AlGaN-based deep-ultraviolet LED chip. Furthermore, the array of ITO hemispheres 411 arranged within the stacked structure 400 encourages current to disperse into the n-type electrode 300, directly improving the current dispersion of the n-type electrode 300. Furthermore, the stacked structure 400 maintains good flatness during the annealing process, facilitating good ohmic contact without compromising the metal's reflectivity, positively impacting the luminous efficiency of the AlGaN-based deep-ultraviolet LED chip.

[0097] Secondly, the stacked structure 400 can reduce the temperature required for the annealing process, which is beneficial to saving energy and protecting the AlGaN-based deep ultraviolet LED chip from high temperature damage; the annealing process is beneficial to eliminating impurities and improving the crystal structure, thereby improving the quality of the stacked structure 400 and the n-type electrode 300, thereby improving the performance and stability of the AlGaN-based deep ultraviolet LED chip.

[0098] The above is a detailed introduction to an AlGaN-based deep ultraviolet LED chip and a preparation method thereof provided in an embodiment of the present invention. Specific examples are used herein to illustrate the principles and implementation methods of the present invention. The description of the above embodiments is only used to help understand the method of the present invention and its core idea. At the same time, for those skilled in the art, according to the idea of ​​the present invention, there will be changes in the specific implementation methods and application scopes. In summary, the content of this specification should not be understood as limiting the present invention.

Claims

1. An AlGaN-based deep ultraviolet LED chip, comprising an epitaxial wafer, and a p-type electrode and an n-type electrode disposed on the epitaxial wafer, characterized in that: The n-type electrode is provided with a stacked structure, the stacked structure comprising an ITO layer, a first Al layer, a first metal layer, a second Al layer, a second metal layer, and a third Al layer stacked in sequence on the n-type electrode; wherein the ITO layer is composed of a plurality of ITO hemispheres arranged in an array, and the first Al layer fills the gaps between the plurality of ITO hemispheres arranged in an array; Under the action of the ITO hemisphere, the side of the first Al layer in contact with the ITO layer forms an uneven rough surface; the ITO hemisphere forms a microcavity, and the Al element of the first Al layer adheres to the microcavity to form the metal structure of the microcavity, and the microcavity and the metal structure form a resonant cavity.

2. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The diameter of the ITO hemisphere ranges from 20 nm to 100 nm.

3. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The spacing between adjacent ITO hemispheres ranges from 10nm to 200nm.

4. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The thickness of the first Al layer is in the range of 60 nm to 80 nm; the thickness of the second Al layer is in the range of 60 nm to 80 nm; and the thickness of the third Al layer is in the range of 80 nm to 100 nm.

5. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The thickness of the first metal layer is in the range of 2 nm to 4 nm.

6. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The thickness of the second metal layer is in the range of 2 nm to 4 nm.

7. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The material of the first metal layer is one of indium, lanthanum, rubidium, ruthenium, zinc and rhodium.

8. The AlGaN-based deep ultraviolet LED chip according to claim 1, wherein: The material of the second metal layer is one of indium, lanthanum, rubidium, ruthenium, zinc and rhodium.

9. A method for preparing an AlGaN-based deep ultraviolet LED chip according to any one of claims 1 to 8, characterized in that: The following steps are involved: S1, preparing an epitaxial wafer with a p-type electrode and an n-type electrode; S2, depositing an original ITO film layer on the n-type electrode; S3, patterning the original ITO film layer to form a plurality of ITO hemispheres arranged in an array; S4, depositing a first Al layer on the plurality of ITO hemispheres arranged in an array; S5. Depositing a first metal layer on the first Al layer; S6. Depositing a second Al layer on the first metal layer; S7, depositing a second metal layer on the second Al layer; S8. Deposit a third Al layer on the second metal layer.

10. The preparation method according to claim 9, characterized in that After step S8, the method further includes: Under an inert atmosphere, the n-type electrode, the plurality of arrayed ITO hemispheres, the first Al layer, the first metal layer, the second Al layer, the second metal layer and the third Al layer are annealed; wherein the annealing temperature range is 300°C-600°C.

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