Inverted three-color Micro-LED and preparation method thereof

Abstract

The invention discloses the field of Micro-LED display, and particularly relates to an inverted three-color Micro-LED and a preparation method thereof.The inverted three-color Micro-LED comprises a first epitaxial wafer, and a first table top is etched on the first epitaxial wafer; a second epitaxial wafer is arranged on the first epitaxial wafer, a second table top is formed on the second epitaxial wafer through etching, and a first through hole extending in the axial direction of the second table top is further formed in the second epitaxial wafer; a first epitaxial wafer is arranged on the first epitaxial wafer, a second epitaxial wafer is arranged on the second epitaxial wafer, a third epitaxial wafer is arranged on the second epitaxial wafer, a third table top is etched on the third epitaxial wafer, a second through hole extending in the axial direction of the third table top is further formed in the third epitaxial wafer, and a third through hole is formed in the side, away from the third table top, of the second through hole. And only 1 / 3 or 1 / 4 space of a traditional mode is occupied, so that the size and the thickness of the display equipment are greatly reduced, and the space utilization rate is improved.

Description

Technical Field

[0001] The present invention relates to the field of Micro-LED display, and in particular to an inverted three-color Micro-LED and a preparation method thereof. Background Art

[0002] Because Micro-LED display devices have the advantages of high efficiency, high brightness, high reliability, energy saving, small size and small thickness, Micro-LED display devices have become a new generation of widely used display devices.

[0003] In the process of manufacturing Micro-LED display devices, it is necessary to first make Micro-LED chips one by one, and then arrange the red, green and blue Micro-LED chips on a temporary substrate three times, and then use the arranged temporary substrate to transfer and bind the Micro-LED chips to the substrate of the display device at one time to achieve full color display device.

[0004] In the development of Micro-LED display technology, mass transfer is a key challenge. The mass transfer process requires high-precision alignment technology, and at the same time, it is necessary to solve the alignment deviation problem that may occur in flip-chip welding. In current technical practice, each Micro-LED chip needs to be grabbed and integrated and transferred one by one, which is not only time-consuming, but also requires extremely high precision of the equipment, increasing the complexity and cost of manufacturing.

[0005] Therefore, those skilled in the art are committed to developing an inverted three-color Micro-LED and a preparation method thereof to save process steps and improve the display accuracy of the Micro-LED. Summary of the invention

[0006] In view of the above-mentioned defects of the prior art, the technical problem to be solved by the present invention is to provide a flip-chip three-color Micro-LED and a preparation method thereof.

[0007] To achieve the above-mentioned object, the present invention provides a flip-chip three-color Micro-LED, comprising a first epitaxial wafer, wherein a first mesa is etched on the first epitaxial wafer;

[0008] A second epitaxial wafer is disposed on the first epitaxial wafer, a second mesa is formed by etching on the second epitaxial wafer, and a first through hole extending axially along the second mesa is also opened on the second epitaxial wafer;

[0009] A third epitaxial wafer is arranged on the second epitaxial wafer, a third mesa is etched on the third epitaxial wafer, a second through hole extending axially along the third mesa is formed on the third epitaxial wafer, and a third through hole is formed on the side of the second through hole away from the third mesa.

[0010] Preferably, the first epitaxial wafer is a red light epitaxial wafer, the second epitaxial wafer is a green light epitaxial wafer, and the third epitaxial wafer is a blue light epitaxial wafer.

[0011] Preferably, the second table passes through the second through hole;

[0012] The first table passes through the first through hole and the third through hole in sequence.

[0013] Preferably, the first epitaxial wafer, the second epitaxial wafer and the third epitaxial wafer are insulated.

[0014] Preferably, the first epitaxial wafer, the second epitaxial wafer and the third epitaxial wafer are flipped.

[0015] The present invention also provides a method for preparing an inverted three-color Micro-LED, comprising the following steps:

[0016] S1, preparing a first chip, a second chip and a third chip, and etching to form a first mesa, a second mesa and a third mesa on the first chip, the second chip and the third chip respectively;

[0017] S2, etching a second through hole and a third through hole on the third chip to the substrate respectively, and the second mesa can pass through the second through hole;

[0018] S3, etching a first through hole on the second chip to the substrate, and the first mesa can pass through the first through hole and the third through hole;

[0019] S4, passivating and protecting each chip separately;

[0020] S5, plating metal electrodes on each chip;

[0021] S6, peeling off the substrates on each chip respectively;

[0022] S7, flip-chip soldering the third table onto the driving circuit;

[0023] S8, inserting the second table into the second through hole and flip-chip soldering it on the driving circuit;

[0024] S9, inserting the first table into the first through hole and the third through hole in sequence, and flip-chip soldering them on the driving circuit.

[0025] Preferably, in step S7, the welding material is zinc.

[0026] Preferably, it is characterized in that: in step S8, the welding material is tin.

[0027] Preferably, in step S9, the welding material is indium.

[0028] The beneficial effects of the present invention are as follows: the present invention can integrate three-color chips in the same pixel unit through a vertical stacking design, occupying only 1 / 3 or 1 / 4 of the space of the traditional method. This design greatly reduces the volume and thickness of the display device and improves space utilization. At the same time, due to the vertical stacking of the three-color chips, more pixel units can be accommodated on the same substrate area, thereby significantly improving the pixel density (PPI), which enables the solution to meet the display requirements of 4K, 8K and even higher resolutions, and provides strong support for the next generation of high-definition display technology. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 It is a structural schematic diagram of a specific implementation mode of the present invention.

[0030] Figure 2 It is a schematic diagram of the assembly of a specific implementation mode of the present invention and a driving circuit.

[0031] 1. First epitaxial wafer; 1a. First mesa; 2. Second epitaxial wafer; 2a. Second mesa; 2b. First through hole; 3. Third epitaxial wafer; 3a. Third mesa; 3b. Second through hole; 3c. Third through hole; 4. Driving circuit. DETAILED DESCRIPTION

[0032] The present invention is further described below in conjunction with the accompanying drawings and embodiments. It should be noted that in the description of the present invention, the terms "upper", "lower", "left", "right", "inner", "outer", etc. indicate directions or positional relationships based on the directions or positional relationships shown in the accompanying drawings, which are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific manner, and therefore cannot be understood as limiting the present invention. The terms "first", "second", "third", etc. are only used for descriptive purposes and cannot be understood as indicating or implying relative importance.

[0033] like Figure 1-2 As shown, a flip-chip three-color Micro-LED includes a first epitaxial wafer 1, a second epitaxial wafer 2, and a third epitaxial wafer 3 stacked in sequence from bottom to top. The above-mentioned epitaxial wafers adopt a flip-chip structure design, the third epitaxial wafer 3 is located at the bottom, and the first epitaxial wafer 1 is located at the top. In this embodiment, the first epitaxial wafer 1 is a red light epitaxial wafer, the second epitaxial wafer 2 is a green light epitaxial wafer, and the third epitaxial wafer 3 is a blue light epitaxial wafer. In other embodiments, epitaxial wafer combinations of other colors can also be selected. The use of this structural design can effectively prevent the light crosstalk phenomenon caused by higher wavelength light generated by energy excitation during light emission, thereby ensuring that each color of light maintains its purity and stability during the emission process, and ultimately improves the clarity of the displayed image and the accuracy of the color.

[0034] In this embodiment: a first mesa 1a is etched on the first epitaxial wafer 1, a second mesa 2a is etched on the second epitaxial wafer 2, a third mesa 3a is etched on the third epitaxial wafer 3, a first through hole 2b extending axially along the second mesa 2a is opened on the second epitaxial wafer 2, a second through hole 3b extending axially along the third mesa 3a is opened on the third epitaxial wafer 3, a third through hole 3c is opened on the side of the second through hole 3b away from the third mesa 3a, the first mesa 1a extends outward through the first through hole 2b and the third through hole 3c in sequence, and the second mesa 2a extends outward through the second mesa 2a.

[0035] In this embodiment: the first epitaxial wafer 1 , the second epitaxial wafer 2 and the third epitaxial wafer 3 are insulated.

[0036] The traditional full-color display method is to arrange the red, green and blue chips in a plane and splice them together. The area occupied by each pixel unit is three times the area of ​​a single color chip, which significantly increases the thickness and space requirements of the display panel. However, through the vertical stacking design of this solution, the red, green and blue chips can be integrated into the same pixel unit, occupying only 1 / 3 or 1 / 4 of the space of the traditional method. This design greatly reduces the size and thickness of the display device and improves space utilization.

[0037] At the same time, due to the vertical stacking of red, green and blue chips, more pixel units can be accommodated on the same substrate area, thus significantly improving the pixel density (PPI). This enables the solution to meet the display requirements of 4K, 8K and even higher resolutions, providing strong support for the next generation of high-definition display technology. This technical solution can not only break through the limitations of traditional planar splicing methods, but also provide a more efficient and compact display solution, which is suitable for the development trend of future high-definition and ultra-high-definition display devices.

[0038] In addition, the present invention also provides a method for preparing a flip-chip three-color Micro-LED, comprising the following steps:

[0039] S1. Prepare a first chip, a second chip and a third chip, and etch the first table 1a, the second table 2a and the third table 3a on the first chip, the second chip and the third chip respectively, wherein the etching depth of the third chip is 1.5-3 μm, and the etching depth of the second chip is 2-4 μm. In this example, the first chip is made of aluminum gallium indium phosphide material. Since the material itself is thick, the etching depth is 4-8 μm to ensure that it can pass through the hole opened at the back. In this embodiment, the first chip is a red light chip, the second chip is a green light chip, and the third chip is a blue light chip. In other embodiments, chips of other colors can also be selected for combination;

[0040] S2, etching the second through hole 3b and the third through hole 3c on the third chip to the substrate respectively, and the second mesa 2a can pass through the second through hole 3b;

[0041] S3, etching a first through hole 2b on the second chip to the substrate, and the first mesa 1a can pass through the first through hole 2b and the third through hole 3c;

[0042] S4, passivating and protecting each chip separately;

[0043] S5, plating metal electrodes on each chip. Since steps S4 and S5 are common steps for preparing Micro-LEDs, they will not be described in detail;

[0044] S6. Peel off the substrates on the first chip, the second chip and the third chip respectively, generally by aurora peeling. After peeling, the first through hole 2b, the second through hole 3b and the third through hole 3c etched in step S2 and step S3 become through holes that are transparent from front to back for the first table 1a and the second table 2a to pass through.

[0045] S7, flip-chip soldering the third mesa 3a to the driving circuit 4, in this embodiment, the soldering material is zinc (melting point 419°C);

[0046] S8, insert the second table 2a into the second through hole 3b and flip-chip solder it onto the driving circuit 4. In this embodiment, the soldering material is tin (melting point 232°C);

[0047] S9. Insert the first table 1a into the first through hole 2b and the third through hole 3c in sequence and flip-chip solder them on the driving circuit 4 to complete the manufacturing process. In this embodiment, the soldering material is indium (melting point 157°C).

[0048] During flip-chip soldering, the soldering material with the highest melting point is used first, and then the melting points are gradually reduced. In this way, the subsequent flip-chip soldering process will not affect the previously flip-chip soldered chips. The soldering materials mentioned above do not only include these few, other metals can also be used as soldering materials, such as copper, gold, etc.

[0049] During the bonding process of the Micro-LED array, epoxy resin can also be used for potting to support the fragile film structure and improve its mechanical strength. After the epoxy resin is cured, the reliability of the stacking structure is further enhanced, ensuring the stability and durability of Micro-LED display devices in industrial applications.

[0050] The present invention utilizes flip-chip welding technology to achieve multi-layer stacking under the premise of single mass transfer, and fixes the three-color Micro-LED chips on the driving circuit 4 through three weldings, which greatly improves the production efficiency. The method is simple and has great market promotion value.

[0051] The preferred specific embodiments of the present invention are described in detail above. It should be understood that a person skilled in the art can make many modifications and changes based on the concept of the present invention without creative work. Therefore, any technical solution that can be obtained by a person skilled in the art through logical analysis, reasoning or limited experiments based on the concept of the present invention on the basis of the prior art should be within the scope of protection determined by the claims.

Claims

1. A flip-chip three-color Micro-LED, characterized by: It comprises a first epitaxial wafer (1), on which a first mesa (1a) is etched; A second epitaxial wafer (2) is arranged on the first epitaxial wafer (1), a second table surface (2a) is formed by etching on the second epitaxial wafer (2), and a first through hole (2b) extending axially along the second table surface (2a) is also formed on the second epitaxial wafer (2); A third epitaxial wafer (3) is arranged on the second epitaxial wafer (2), a third table (3a) is etched on the third epitaxial wafer (3), a second through hole (3b) extending axially along the third table (3a) is also formed on the third epitaxial wafer (3), and a third through hole (3c) is formed on the side of the second through hole (3b) away from the third table (3a).

2. The flip-chip three-color Micro-LED according to claim 1, characterized in that: The first epitaxial wafer (1) is a red light epitaxial wafer, the second epitaxial wafer (2) is a green light epitaxial wafer, and the third epitaxial wafer (3) is a blue light epitaxial wafer.

3. The flip-chip three-color Micro-LED according to claim 1, characterized in that: The second table surface (2a) passes through the second through hole (3b); The first table surface (1a) passes through the first through hole (2b) and the third through hole (3c) in sequence.

4. The flip-chip three-color Micro-LED according to claim 1, characterized in that: The first epitaxial wafer (1), the second epitaxial wafer (2) and the third epitaxial wafer (3) are subjected to insulation treatment.

5. The flip-chip three-color Micro-LED according to claim 1, characterized in that: The first epitaxial wafer (1), the second epitaxial wafer (2) and the third epitaxial wafer (3) are arranged in an inverted manner.

6. A method for preparing an inverted three-color Micro-LED, characterized in that: The following steps are involved: S1, preparing a first chip, a second chip and a third chip, and etching to form a first mesa (1a), a second mesa (2a) and a third mesa (3a) on the first chip, the second chip and the third chip respectively; S2, etching a second through hole (3b) and a third through hole (3c) on the third chip to the substrate, respectively, so that the second mesa (2a) can pass through the second through hole (3b); S3, etching a first through hole (2b) on the second chip to the substrate, and the first mesa (1a) can pass through the first through hole (2b) and the third through hole (3c); S4, passivating and protecting each chip separately; S5, plating metal electrodes on each chip; S6, peeling off the substrates on each chip respectively; S7, flip-chip welding the third table (3a) onto the driving circuit (4); S8, inserting the second table (2a) into the second through hole (3b) and flip-chip soldering it onto the driving circuit (4); S9, inserting the first table (1a) into the first through hole (2b) and the third through hole (3c) in sequence, and flip-chip soldering them onto the driving circuit (4).

7. The method for preparing a flip-chip three-color Micro-LED according to claim 6, characterized in that: In step S7, the welding material is zinc.

8. The method for preparing a flip-chip three-color Micro-LED according to claim 6, characterized in that: In step S8, the soldering material is tin.

9. The method for preparing a flip-chip three-color Micro-LED according to claim 6, characterized in that: In step S9, the welding material is indium.

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