Vertically stacked full-color Micro-LED, preparation method and display panel
By designing a multi-layer LED epitaxial structure and fine electrode structure in a vertical stacked Micro-LED chip, the problems of epitaxial damage and high number of photolithography in the prior art are solved, and a high yield and low cost manufacturing process is achieved.
Patent Information
- Application Number
- CN202510234841.7
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-28
- Publication Date
- 2025-06-03
AI Technical Summary
There are problems of epitaxial damage and core particles during the manufacturing process of existing vertical stacked Micro-LED chips, and excessive lithography exposures lead to low yields and cannot meet production needs.
The vertical stacked full-color Micro-LED design is adopted, including epitaxial structure and electrode structure. The epitaxial structure consists of blue, green and red LED epitaxial layers. The electrode structure includes a variety of electrode through-holes and fine designs of electrode materials, and an insulating material and an omnidirectional all-band reflective layer are provided in the structure.
It significantly reduces the number of lithography times, improves the yield of the chip, simplifies the manufacturing process, and reduces process costs.
Smart Images
Figure CN120091673A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the technical field of semiconductor display chips, and particularly relates to a vertically stacked full-color Micro-LED, a preparation method and a display panel. Background Art
[0002] The vertical stacking technology can achieve seamless connection of multiple chips to achieve higher brightness and resolution, providing a feasible method for realizing higher-resolution displays. The vertical stacking Micro-LED technology can be achieved in two ways: one is to stack multiple Micro-LED chips together to form a large chip; the other is to separately package multiple Micro-LED chips on different chips and then assemble them together. No matter which method is adopted, precise design and optimization are required in aspects such as circuits and optics to ensure the performance and stability of the chips.
[0003] Currently, the manufacturing of vertically stacked Micro-LED chips generally requires multiple bonding and peeling processes, which often accompany epitaxial breakage and die loss. At the same time, vertically stacked wafers often face more than 40 exposure times, and excessive exposure times will lead to too low a yield, so the current vertical stacking technology does not meet the production requirements. Summary of the Invention
[0004] In order to solve the problems existing in the prior art, the present invention provides a vertically stacked full-color Micro-LED, which is characterized in that it includes an epitaxial structure and an electrode structure; The epitaxial structure includes a blue LED epitaxial layer, a green LED epitaxial layer and a red LED epitaxial layer from bottom to top; A first electrode through hole leading to the blue LED epitaxial layer is provided in the green LED epitaxial layer and the red LED epitaxial layer, a second electrode through hole is provided outside the blue LED epitaxial layer, the green LED epitaxial layer and the red LED epitaxial layer, a third electrode through hole is provided outside the red LED epitaxial layer, and a fourth electrode through hole and a fifth electrode through hole leading to the green LED epitaxial layer are provided; The electrode structure includes a blue anode electrode, a common red and blue cathode electrode, a red anode electrode, a green anode electrode and a green cathode electrode; The blue anode electrode, the common red and blue cathode electrode, the red anode electrode, the green anode electrode and the green cathode electrode are respectively arranged in the first to fifth electrode through holes.
[0005] Further, insulating materials are provided on the sidewalls of the blue LED epitaxial layer, the green LED epitaxial layer, and the red LED epitaxial layer, outside the blue LED epitaxial layer, on the tops of the green LED epitaxial layer and the red LED epitaxial layer, and on the sidewalls of the first to fifth electrode vias; Omnidirectional and full-band reflection layers are further provided on the insulating materials on the sidewalls of the blue LED epitaxial layer, the green LED epitaxial layer, and the red LED epitaxial layer and on the outside of the red LED epitaxial layer.
[0006] Further, the omnidirectional and full-band reflection layer sequentially includes a first total reflection layer, a DBR layer, a metal reflection layer, and a second total reflection layer. Among them, the first total reflection layer is composed of a low-refractive-index transparent insulating material, and its thickness is equal to the red light emission wavelength divided by the material refractive index; the second total reflection layer is composed of a high-refractive-index transparent insulating material, and its thickness is equal to the blue light emission wavelength divided by the material refractive index; the DBR layer is a reflective optical structure formed by alternately stacking high-refractive-index materials and low-refractive-index materials with gradually changing thicknesses. The film layer close to the epitaxial structure is designed for the red light wavelength, and the film layer far from the epitaxial structure is designed for the blue light wavelength. The high-refractive-index material can be Ti 3 O 5 or TiO 2 at least one of them, and the low-refractive-index material is SiO 2 ; the metal reflection layer includes at least one of Cr / Au / Ag, Ni / Ag, Ag / Ti / W with a thickness of 100 - 500 nm.
[0007] Further, the blue LED epitaxial layer includes a blue n-type layer, a blue multi-quantum well layer, and a blue p-type layer from bottom to top; The green LED epitaxial layer includes a green n-type layer, a green multi-quantum well layer, a green p-type layer, and a transparent conductive layer from bottom to top; The red LED epitaxial layer includes a first contact layer, a red p-type layer, a red multi-quantum well layer, a red n-type layer, and a second contact layer from bottom to top.
[0008] Further, the blue LED epitaxial layer and the green LED epitaxial layer are connected by a connection structure, and the connection structure includes a tunnel junction and a current blocking layer on the top of the tunnel junction. The composition of the tunnel junction includes, but is not limited to, n + -GaN / p + -GaN, n + -GaN / i-InGaN / p + -GaN, n + -GaN / i-AlGaN / p + -GaN, etc.
[0009] Further, the green LED epitaxial layer and the red LED epitaxial layer are connected by a bonding method.
[0010] Preferably, the bonding is performed by thermocompression bonding. Among them, the bonding layer material is an insulator, including Al 2 O 3 -SiO 2 、SiO 2 -SiO 2 and other bonding layer structures.
[0011] Furthermore, it also includes electrode pads, and the electrode pads include the first to fifth pads respectively connected to the blue light anode electrode, the red and blue light common cathode electrode, the red light anode electrode, the green light anode electrode, and the green light cathode electrode.
[0012] The present invention also provides a method for manufacturing the above-mentioned vertically stacked full-color Micro-LED, including, Obtaining a substrate, on which a blue light epitaxial material and a green light epitaxial material are sequentially arranged; Connecting a red light epitaxial material on the green light epitaxial material of the substrate, and forming a first electrode through hole reaching the blue light epitaxial material within the green light epitaxial material and the red light epitaxial material, forming a second electrode through hole in the blue light epitaxial material, the green light epitaxial material, and the red light epitaxial material, forming a third electrode through hole, a fourth electrode through hole reaching the green light epitaxial material, and a fifth electrode through hole in the red light LED epitaxial layer material. Correspondingly, a blue light LED structure, a green light LED structure, and a red light LED structure are formed; Preparing a blue light anode electrode, a red and blue light common cathode electrode, a red light anode electrode, a green light anode electrode, and a green light cathode electrode respectively in the first to fifth electrode through holes, and then peeling off the substrate.
[0013] Furthermore, the first electrode through hole, the second electrode through hole, and the fifth electrode through hole are prepared by stepwise etching; The blue light anode electrode, the red and blue light common cathode electrode, the red light anode electrode, the green light anode electrode, and the green light cathode electrode are prepared after insulating materials are prepared on the inner walls of the first to fifth electrode through holes.
[0014] Preferably, the stepwise etching preparation means that first, a first bottom layer electrode, a second bottom layer electrode, and a third bottom layer electrode are deposited in the blue light epitaxial material and the green light epitaxial material. After connecting the red light epitaxial material, a first upper through hole, a second upper through hole, and a third upper through hole are etched in the red light epitaxial material, and a first upper electrode, a second upper electrode, and a third upper electrode are deposited to obtain the blue light anode electrode, the red and blue light common cathode electrode, and the green light cathode electrode.
[0015] The present invention also provides a display panel, including the above-mentioned vertically stacked full-color Micro-LED and a driving backplane; A common cathode circuit and an anode power supply electrode are provided on the driving backplane. The common cathode circuit is connected to a red and blue common cathode electrode and a green cathode electrode; the anode power supply electrode is connected to a blue anode electrode, a red anode electrode, and a green anode electrode.
[0016] Compared with the prior art, the present invention has the following beneficial effects: During the preparation process of the vertical stacked full-color Micro-LED of the present invention, the number of photolithography times can be greatly reduced, thereby significantly improving the yield. Compared with the traditional preparation process, the vertical stacked Micro-LED chip of the present invention has a simple manufacturing process and low process cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0017] In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the following will briefly introduce the drawings required for the description of the embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.
[0018] Figure 1 The top view of the vertical stacked full-color Micro-LED is shown. In the figure, the omnidirectional and full-band reflection layer is omitted and not shown; Figure 2 Shows Figure 1 The schematic cross-sectional structure along the AA section; Figure 3 Shows Figure 1 The schematic cross-sectional structure along the BB section; Figure 4 Shows Figure 1 The schematic cross-sectional structure along the CC section; Figure 5 The AA cross-sectional view of the substrate with blue light epitaxial material, connection material, and green light epitaxial material is shown; Figure 6 The BB cross-sectional view of the product of step S102 is shown; Figure 7 The BB cross-sectional view of the product of step S103 is shown; Figure 8 The AA cross-sectional view of the product of step S104 is shown; Figure 9 The AA cross-sectional view of the product of step S105 is shown; Figure 10 The AA cross-sectional view of the product of step S106 is shown; Figure 11 The AA cross-sectional view of the product of step S107 is shown; Figure 12Shows the BB cross-sectional view of the product in step S107; Figure 13 Shows the AA cross-sectional view of the product in step S108; Figure 14 Shows the AA cross-sectional view of the product in step S109; Figure 15 Shows the AA cross-sectional view of the product in step S110; Figure 16 Shows the AA cross-sectional view of the product in step S111; Figure 17 Shows the AA cross-sectional view of the product in step S112; Figure 18 Shows the AA cross-sectional view of the product in step S113; Figure 19 Shows the BB cross-sectional view of the product in step S113; Figure 20 Shows the CC cross-sectional view of the product in step S113; Figure 21 Shows the AA cross-sectional view of the product in step S114; Figure 22 Shows the BB cross-sectional view of the product in step S114; Figure 23 Shows the CC cross-sectional view of the product in step S114; Figure 24 Shows the AA cross-sectional view of the product in step S115; Figure 25 Shows the AA cross-sectional view of the product in step S116; Figure 26 Shows the AA cross-sectional view of the product in step S117; Figure 27 Shows the cross-sectional view of the omnidirectional and full-band reflection layer; Figure 28 Shows the AA cross-sectional view of the product in step S118; Figure 29 Shows the AA cross-sectional view of the product in step S119; Figure 30 Shows the scanning electron microscope image of the exposed surface of the blue light n-GaN layer; Figure 31 Shows the AA cross-sectional view of the product in step S120; Figure 32 Shows the simulated reflection curves of the omnidirectional and full-band reflection layer in Example 1 and the DBR layer in the comparative example at incident angles of 0° and 60° Figure 33 Shows the top view of the display panel; Explanation of reference numerals: 1. Substrate; 2. Blue light LED epitaxial layer; 201. Blue light n-GaN layer; 202. Blue light multi-quantum well layer; 203. Blue light p-GaN layer; 3. Connection structure; 301. GaN tunnel junction; 302. Undoped GaN layer; 4. Green light LED epitaxial layer; 401. Green light n-GaN layer; 402. Green light multi-quantum well layer; 403. Green light p-GaN layer; 5. Indium tin oxide layer; 6. Blue light anode electrode; 601. First bottom electrode; 7. Red and blue common cathode electrode; 701. Second bottom electrode; 8. Red light anode electrode; 9. Green light anode electrode; 10. Green light cathode electrode; 1001. Third bottom electrode; 11. First insulating material; 12. Red light LED epitaxial layer; 1201. Red light p-GaP contact layer; 1202. Red light p-AlGaInP layer; 1203. Red light multi-quantum well layer; 1204. Red light n-AlGaInP layer; 1205. n-GaAs contact layer; 1206. Second electrode hole; 13. Second insulating material; 1301. Fourth electrode through hole; 1302. First upper through hole; 1303. Second upper through hole; 1304. Third upper through hole; 1305. Third electrode through hole; 14. Omnidirectional and full-band reflection material; 15. Omnidirectional and full-band reflection layer; 1501. First total reflection layer; 1502. DBR layer; 1503. Metal reflection layer; 1504. Second total reflection layer; 16. Electrode pad; 1601. First pad; 1602. Second pad; 1603. Third pad; 1604. Fourth pad; 1605. Fifth pad; 17. Third insulating material; 1701. Collimating lens; 18. Driving backplane; 1801. Common cathode circuit; 1802. Anode power supply electrode. Detailed implementation manners
[0019] In the description of the present application, it should be understood that the terms "first" and "second" are only used for descriptive purposes and cannot be construed as indicating or implying relative importance or implicitly specifying the quantity of the indicated technical features. Thus, the features defined with "first" and "second" may explicitly or implicitly include one or more of the described features. In the description of the present application, "a plurality of" means two or more unless otherwise specifically defined.
[0020] In the description of the present application, it should be noted that unless otherwise clearly specified and defined, the terms "installation", "connection", and "linkage" should be understood in a broad sense. For example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection, an electrical connection, or a connection that allows mutual communication; it can be a direct connection, or an indirect connection through an intermediate medium, and can be the communication inside two components or the interaction relationship between two components. For those of ordinary skill in the art, the specific meanings of the above terms in the present application can be understood according to specific circumstances.
[0021] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the specific embodiments of the present invention and the accompanying drawings of the specification. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all of the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the scope of protection of the present invention.
[0022] Embodiment 1 As Figures 1-4 shown in the vertical stacked full-color Micro-LED, its manufacturing method includes the following steps: S101: As shown in, obtain a sapphire substrate 1. As Figure 5 shown, a blue light epitaxial material, a connection material, and a green light epitaxial material are sequentially arranged on this substrate 1. Among them, the blue light epitaxial material includes a blue light n-GaN layer 201, a blue light multi-quantum well material, and a blue light p-GaN material; the connection structure includes a GaN tunnel junction material and an undoped GaN material on the top of the GaN tunnel junction; the green light epitaxial material includes a green light n-GaN material, a green light multi-quantum well material, and a green light p-GaN material; and indium tin oxide material is deposited on the surface of the green light p-GaN by magnetron sputtering process.
[0023] S102: As Figure 6 shown, use photolithography and ICP etching process to etch the indium tin oxide material to the green light n-GaN material; S103: As Figure 7 shown, use photolithography and electron beam evaporation process to deposit a third bottom electrode 1001 on the green light n-GaN material; S104: As Figure 8 shown, use photolithography and ICP etching process to etch the indium tin oxide material to the blue light n-GaN layer 201.
[0024] S105: As Figure 9 shown, use photolithography and electron beam evaporation process to deposit a second bottom electrode 701 on the blue light n-GaN layer 201.
[0025] S106: AsFigure 10 As shown, indium tin oxide is etched to the GaN tunnel junction material by photolithography and ICP etching processes to form a first electrode hole.
[0026] S107: Indium tin oxide is etched to the substrate by photolithography and ICP etching processes to expose the isolation trench. After this step, a blue light LED epitaxial layer 2, a connection structure 3, and a green light LED epitaxial layer 4 are formed on the substrate. Among them, the blue light LED epitaxial layer 2 includes a blue light n-GaN layer 201, a blue light multiple quantum well layer 202, and a blue light p-GaN layer 203; the bonding structure 3 includes a GaN tunnel junction layer 301 and an undoped GaN layer 302; the green light LED epitaxial layer 4 includes a green light n-GaN layer 401, a green light multiple quantum well layer 402, and a green light p-GaN layer 403. There is an indium tin oxide layer 5 on the top of the green light LED epitaxial layer 4. As Figure 11 shown, a first insulating material 11 is deposited by PECVD process to fill the isolation trench and the first electrode trench, on the outside of the blue light LED epitaxial layer 2, and on the outside and upper end of the green light LED epitaxial layer 4. At this time, the second bottom electrode 701 is enclosed by the first insulating material 11, and at the same time as Figure 12 shown, the third bottom electrode 1001 is enclosed by the first insulating material 11.
[0027] S108: As Figure 13 shown, the first insulating material 11 in the first electrode trench is etched by photolithography and ICP etching processes to form a first bottom through hole.
[0028] S109: As Figure 14 shown, a first bottom electrode 601 is deposited in the first bottom through hole by photolithography and electron beam evaporation processes.
[0029] S110: A red light epitaxial wafer is obtained, which sequentially includes a red light p-GaP contact material, a red light p-AlGaInP material, a red light multiple quantum well material, a red light n-AlGaInP material, a red light n-GaAs contact material, and a GaAs substrate from top to bottom. The red light epitaxial wafer is turned upside down, and the red light p-GaP contact material of the red light epitaxial wafer is bonded to the first insulating material on the top of the green light LED epitaxial layer by a thermal compression bonding method. After bonding, the GaAs substrate of the red light epitaxial wafer is removed by a wet etching process to obtain the product as Figure 15 shown.
[0030] S111: As Figure 16As shown, the first insulating material 11 etched from the red light n-GaAs contact material to the top of the green light LED epitaxial layer 4 is etched using a photolithography and ICP etching process, and a second electrode hole 1206 is formed in the red light epitaxial wafer; after this step, a red light LED epitaxial layer 12 is formed on the green light LED epitaxial layer 4, and the red light LED epitaxial layer 12 includes, from bottom to top, a red light p-GaP contact layer 1201, a red light p-AlGaInP layer 1202, a red light multi-quantum well layer 1203, a red light n-AlGaInP layer 1204, and an n-GaAs contact layer 1205.
[0031] S112, as Figure 17 shown, a second insulating material 13 is deposited using a PECVD process to cover the top of the green light LED epitaxial layer 4 and the second electrode hole 1206.
[0032] S113, the second insulating material 13 on the top of the green light LED epitaxial layer 4 and in the second electrode hole 1206 is etched using a photolithography and ICP etching process, as Figure 18 shown, a fourth electrode through-hole 1301 communicating with the indium tin oxide layer 5, a first upper through-hole 1302 communicating with the first bottom electrode 601, and a second upper through-hole 1303 communicating with the second bottom electrode 701 are formed; as Figure 19 shown, a third upper through-hole 1304 communicating with the third bottom electrode 1001 is formed; as Figure 20 shown, a third electrode through-hole 1305 communicating with the red light p-GaP contact layer 1201 is formed; S114, electrode materials are deposited in the fourth electrode through-hole 1301, the first upper through-hole 1302, the second upper through-hole 1303, the third upper through-hole 1304, and the third electrode through-hole 1305 using a photolithography and electron beam evaporation process, as Figure 21 shown, a green light anode electrode 9, a blue light anode electrode 6, and a red and blue common cathode electrode 7 are formed; as Figure 22 shown, a green light cathode electrode 10 is formed; as Figure 23 shown, a red light anode electrode 8 is formed.
[0033] S115, the first insulating material 11 and the second insulating material 13 outside the blue light LED epitaxial layer 2, the green light LED epitaxial layer 4, and the red light LED epitaxial layer 12 are etched using a photolithography and ICP etching process, as Figure 24 shown.
[0034] S116, a first total reflection material is deposited on the surface of the product obtained in S115 and the top of the red light LED epitaxial layer 12 in sequence using a PECVD process, a DBR material is deposited using an electron beam deposition process, a metal reflection material is evaporated using an electron beam evaporation process, and a second total reflection material is deposited using a PECVD process, asFigure 25 As shown, an omnidirectional and all-band reflection material 14 is formed.
[0035] S117. Using a photolithography process, an ICP etching process, and a wet etching process, etch away the omnidirectional and all-band reflection material 14 near the blue light anodic electrode 6, the red and blue light common cathodic electrode 7, the red light anodic electrode 8, the green light anodic electrode 9, and the green light cathodic electrode 10, as Figure 26 and Figure 27 shown, to form an omnidirectional and all-band reflection layer 15. The omnidirectional and all-band reflection layer 15 includes a first total reflection layer 1501, a DBR layer 1502, a metal reflection layer 1503, and a second total reflection layer 1504; and obtain a first pad via hole, a second pad via hole, a third pad via hole, a fourth pad via hole, and a fifth pad via hole.
[0036] S118. As Figure 28 shown, prepare an electrode pad 16. Specifically, use a photolithography and electron beam evaporation process to form a first pad 1601, a second pad 1602, a third pad 1603, a fourth pad 1604, and a fifth pad 1605 that are respectively connected to the blue light anodic electrode 6, the red and blue light common cathodic electrode 7, the red light anodic electrode 8, the green light anodic electrode 9, and the green light cathodic electrode 10 in the first to fifth pad via holes.
[0037] S119. As Figure 29 and Figure 30 shown, flip the product obtained in S118 upside down and use a laser lift-off process to lift off the substrate 1 so that the blue light n-GaN layer 201 is exposed.
[0038] S120. As Figure 31 shown, use a PECVD process and a photolithography process to deposit a third insulating material 17 on the exposed blue light n-GaN layer 201.
[0039] S121. Using a photolithography and ICP etching process, etch the third insulating material 17 to form a collimating lens 1701 on the blue light n-GaN layer 201, and obtain a vertically stacked full-color Micro-LED as Figure 2 shown.
[0040] In this embodiment, the first insulating material 11, the second insulating material 13, and the third insulating material 17 are of the same material, and are all SiO 2 .
[0041] The first total reflection layer 1501 of the omnidirectional and all-band reflection layer 15 is Al with a thickness of 260 nm 2 O 3 ; The DBR layer 1502 is, from the inside to the outside, 4 pairs of SiO 2 (110 nm) / Ti 3 O 5(70 nm), 4 pairs of SiO 2 (90 nm) / Ti 3 O 5 (60 nm), 4 pairs of SiO 2 (85 nm) / Ti 3 O 5 (50 nm); the metal reflective layer 1503 is Ni / Ag with a thickness of 200 nm; the second total reflection layer 1504 is SiO with a thickness of 425 nm 2 .
[0042] As Figure 32 shown ( Figure 32 in, the omnidirectional and full-band reflector is the omnidirectional and full-band reflective layer; DBR refers to the DBR layer), for the omnidirectional and full-band reflective layer 15 of this embodiment at an incident angle of 0°, the reflectivities for red light at 620 nm, green light at 530 nm, and blue light at 460 nm are 98.5%, 96.3%, and 97.2% respectively. At an incident angle of 60°, the reflectivities for red light at 620 nm, green light at 530 nm, and blue light at 460 nm are 97.9%, 97.9%, and 95.8% respectively. It can be seen that the omnidirectional and full-band reflective layer 15 of this embodiment has a high reflection ability for visible light at any angle and full band.
[0043] Overall, in the preparation method of this embodiment, only 1 wafer bonding and 17 photolithography processes are required, which can significantly improve the process yield of vertically stacked RGB Micro-LEDs. And by combining the omnidirectional and full-band reflective layer and the collimating lens, high luminous efficiency Micro-LEDs and small light output angles can be achieved.
[0044] Embodiment 2 A method for preparing a display panel, based on the vertically stacked full-color Micro-LED prepared in Embodiment 1, the steps are as follows, T101. Obtain a driving backplane, on which a common cathode circuit and an anode power supply electrode are arranged; T102. As Figure 33 shown, adopt the eutectic bonding process to bond the blue anode electrode, red anode electrode, and green anode electrode of the vertically stacked full-color Micro-LED to the anode power supply electrode, and bond the red and blue common cathode electrodes and the green cathode electrode to the common cathode circuit to obtain a display panel.
[0045] Comparative Example 1 Compared with Embodiment 1, a vertically stacked full-color Micro-LED is obtained by only replacing the omnidirectional and full-band reflective layer with a DBR layer of the same structure..
[0046] As Figure 32As shown, at an incident angle of 0°, the reflectivities of Comparative Example 1 for red light at 620 nm, green light at 530 nm, and blue light at 460 nm are 99.9%, 69.3%, and 56.9% respectively. On the contrary, the reflectivities of Example 1 for red light at 620 nm, green light at 530 nm, and blue light at 460 nm reach 98.5%, 96.3%, and 97.2% respectively; at an incident angle of 60°, the reflectivities of Comparative Example 1 for red light at 620 nm, green light at 530 nm, and blue light at 460 nm are 93.6%, 99.8%, and 73.8% respectively. On the contrary, the reflectivities of Example 1 for red light at 620 nm, green light at 530 nm, and blue light at 460 nm reach 97.9%, 97.9%, and 95.8% respectively. Therefore, the reflective layer 25 provided in this application has a high reflection ability for visible light at any angle and over the entire wavelength range.
[0047] Finally, it should be noted that the above are only the preferred embodiments of the present invention and are not used to limit the present invention. Although the present invention has been described in detail with reference to the foregoing embodiments, for those skilled in the art, they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements for some of the technical features. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.
Claims
1. A vertically stacked full-color Micro-LED, characterized in that: including epitaxial structure and electrode structure; The epitaxial structure includes, from bottom to top, a blue LED epitaxial layer, a green LED epitaxial layer and a red LED epitaxial layer; The green LED epitaxial layer and the red LED epitaxial layer are provided with a first electrode through hole directly reaching the blue LED epitaxial layer, the blue LED epitaxial layer, the green LED epitaxial layer and the red LED epitaxial layer are provided with a second electrode through hole outside, and the red LED epitaxial layer is provided with a third electrode through hole and a fourth electrode through hole and a fifth electrode through hole directly reaching the green LED epitaxial layer outside; The electrode structure includes a blue light anode electrode, a red and blue light common cathode electrode, a red light anode electrode, a green light anode electrode and a green light cathode electrode; The blue light anode electrode, the red and blue light common cathode electrode, the red light anode electrode, the green light anode electrode and the green light cathode electrode are respectively arranged in the first to fifth electrode through holes.
2. The vertically stacked full-color Micro-LED according to claim 1, characterized in that: Insulating material is provided on the side walls of the blue LED epitaxial layer, the green LED epitaxial layer, and the red LED epitaxial layer, the outside of the blue LED epitaxial layer, the top of the green LED epitaxial layer, the red LED epitaxial layer, and the side walls of the first to fifth electrode through holes; An omnidirectional full-band reflective layer is also arranged on the side walls of the blue light LED epitaxial layer, the green light LED epitaxial layer, the red light LED epitaxial layer and the insulating material outside the red light LED epitaxial layer.
3. The vertically stacked full-color Micro-LED according to claim 2, characterized in that: The omnidirectional and full-band reflection layer includes a first total reflection layer, a DBR layer, a metal reflection layer and a second total reflection layer in sequence; The material of the first total reflection layer is Al2O3 or SiO2 or SiN x , thickness is between 200-400nm; DBR layer is composed of several pairs of SiO2 / Ti3O5, SiO2 thickness is between 85-110nm, Ti3O5 thickness is between 50-70nm; metal reflection layer thickness is between 50-300nm; the second total reflection layer material is Al2O3 or SiO2 or SiN x , with a thickness between 300-500nm.
4. The vertically stacked full-color Micro-LED according to claim 1, characterized in that: The blue light LED epitaxial layer includes a blue light n-type layer, a blue light multi-quantum well layer and a blue light p-type layer from bottom to top; The green LED epitaxial layer includes, from bottom to top, a green n-type layer, a green multi-quantum well layer, a green p-type layer and a transparent conductive layer; The red light LED epitaxial layer comprises, from bottom to top, a first contact layer, a red light p-type layer, a red light multi-quantum well layer, a red light n-type layer, and a second contact layer.
5. The vertically stacked full-color Micro-LED according to claim 1, characterized in that: The blue LED epitaxial layer and the green LED epitaxial layer are connected via a connection structure, and the connection structure includes a tunnel junction and a current blocking layer on the top of the tunnel junction.
6. The vertically stacked full-color Micro-LED according to claim 1, characterized in that: The green light LED epitaxial layer and the red light LED epitaxial layer are connected by bonding.
7. The vertically stacked full-color Micro-LED according to claim 1, characterized in that: It also includes electrode pads, which include first to fifth pads connected to the blue light anode electrode, the red and blue light common cathode electrode, the red light anode electrode, the green light anode electrode and the green light cathode electrode respectively.
8. A method for preparing vertically stacked full-color Micro-LEDs, characterized in that: include, Obtaining a substrate, on which a blue light epitaxial material and a green light epitaxial material are sequentially arranged; Connecting the red epitaxial material to the green epitaxial material of the substrate, and forming a first electrode through hole directly reaching the blue epitaxial material in the green epitaxial material and the red epitaxial material, forming a second electrode through hole in the blue epitaxial material, the green epitaxial material and the red epitaxial material, forming a third electrode through hole, a fourth electrode through hole directly reaching the green epitaxial material and a fifth electrode through hole in the red LED epitaxial layer material, and accordingly forming a blue LED structure, a green LED structure and a red LED structure; A blue light anode electrode, a red and blue light common cathode electrode, a red light anode electrode, a green light anode electrode and a green light cathode electrode are prepared in the first to fifth electrode through holes respectively, and then the substrate is peeled off.
9. The method for preparing a vertically stacked full-color Micro-LED according to claim 8, characterized in that: The first electrode through hole, the second electrode through hole and the fifth electrode through hole are prepared by step-by-step etching; The blue light anode electrode, the red and blue light common cathode electrode, the red light anode electrode, the green light anode electrode and the green light cathode electrode are prepared after the insulating material is prepared on the inner walls of the first to fifth electrode through holes.
10. A display panel, characterized in that: Comprising the vertically stacked full-color Micro-LED and a driving backplane as described in any one of claims 1 to 7; The driving backplane is provided with a common cathode circuit and an anode power supply electrode, the common cathode circuit is connected to the red and blue light common cathode electrode and the green light cathode electrode; the anode power supply electrode is connected to the blue light anode electrode, the red light anode electrode and the green light anode electrode.