Sub-millimeter light emitting diode and preparation method thereof

Abstract

The invention relates to the technical field of Mini LED display, in particular to a sub-millimeter light-emitting diode and a preparation method thereof, and the method comprises the following steps: sequentially arranging a distributed Bragg reflector, a diffusion layer, a quantum dot layer and an organic silicon protection layer on a substrate covered with a pyrolysis film; carrying out wafer expansion on the GaN chip to be arranged at a specific distance through a blue film, and carrying out alignment bonding on the GaN chip and the substrate coated with the organic silicon protection layer; filling white wall glue between the channels of the GaN chips, and etching the division retaining walls, the organic silicon protection layer, the quantum dot layer, the diffusion layer and the DBR layer between the GaN chips to form the channels; a silicon nitride layer is deposited on the surface of the side wall of the channel through ALD or PECVD, and then the sub-millimeter light-emitting diode is obtained, packaging protection of the quantum dot layer is achieved by adopting an inorganic-organic material composite alternating mode, a strong barrier effect on water and oxygen is achieved, and high performance and high reliability of a device are guaranteed.

Description

Technical Field

[0001] This invention relates to the field of Mini LED display technology, specifically to a sub-millimeter light-emitting diode and its fabrication method. Background Technology

[0002] Mini LED (submillimeter-sized light-emitting diode) is a new type of display technology that solves the problems of low brightness and low contrast of traditional LCD (liquid crystal display module). Its display effect is no less than that of OLED (organic light-emitting diode), and it does not have problems such as burn-in and short lifespan. Therefore, it has attracted widespread attention and research in the display industry.

[0003] Quantum dots (QDs), also known as "nanocrystalline materials," are semiconductor nanostructures in which electrons in the conduction band, holes in the valence band, and excitons are bound in three spatial directions. They have a particle size of 1-10 nm and are composed of IIB-VIB or IIIB-VB elements, such as CdS, CdSe, InP, and InAs. Because electrons and holes are quantum-confined, the continuous band structure becomes a discrete energy level structure with molecular characteristics, allowing them to emit fluorescence when excited. Quantum dots, as display materials, are characterized by high color gamut, pure color, and long lifetime.

[0004] Mini LED displays can be categorized into two types based on their light-emitting principle: photoluminescence and electroluminescence. Electroluminescence refers to the Mini direct-view display solution, which is mostly used in large-screen displays such as commercial displays. Photoluminescence mainly refers to the Mini LED backlight solution, which is further divided into COB (Chip On Board) and POB (Package On Board).

[0005] POB (Polymer Optical Array) converts blue light using inorganic phosphors. Due to material limitations, this approach suffers from a low color gamut and limited improvement in display quality. COB (Copyright Optical Array), on the other hand, uses a gallium nitride (GaN) chip paired with a quantum dot film to achieve white light conversion. While this solution can achieve high-quality display, quantum dot materials are susceptible to water and oxygen corrosion, leading to performance degradation. Therefore, high water and oxygen barrier materials are required for encapsulation to ensure high reliability. This presents challenges for quantum dot encapsulation, especially in more complex environments such as automotive displays. Summary of the Invention

[0006] To address the shortcomings of existing technologies, this invention discloses a sub-millimeter light-emitting diode and its fabrication method, thereby solving the aforementioned problems.

[0007] This invention is achieved through the following technical solution:

[0008] In a first aspect, the present invention provides a method for fabricating a sub-millimeter light-emitting diode, comprising the following steps:

[0009] A distributed Bragg reflector, a diffusion layer, a quantum dot layer, and an organosilicon protective layer are sequentially disposed on a substrate covered with a pyrolysis film.

[0010] The GaN chip is expanded into a specific spacing by using a blue film, and then the GaN chip is aligned and bonded to a substrate coated with an organosilicon protective layer.

[0011] White wall adhesive is filled between the channels of GaN chips, and the separation barrier, silicone protective layer, quantum dot layer, diffusion layer and DBR layer between GaN chips are etched out to form the channels.

[0012] Sub-millimeter light-emitting diodes are obtained by depositing a silicon nitride layer on the sidewall surface of the channel through ALD or PECVD.

[0013] Furthermore, the substrate is either a glass substrate or a silicon substrate.

[0014] Furthermore, the distributed Bragg reflector is prepared by plasma chemical vapor deposition and contains two inorganic materials with different refractive indices.

[0015] Furthermore, the thickness of the organosilicon protective layer is 30-60 μm, and the thickness of the diffusion layer is 30-60 μm, wherein the diffusion layer comprises organic resin material, organic diffusion particles, organic solvent and additives.

[0016] Furthermore, the resin material is one or more of acrylic resin, silicone resin, epoxy resin, and polyvinyl chloride resin;

[0017] The diffused particles are one or more of PMMA (polymethyl methacrylate), PBMA (polybutyl methacrylate), PA (nylon), and PU (polyurethane).

[0018] Furthermore, the average particle size of the organic diffusion particles is between 1-15 μm, and the additive plays a leveling role.

[0019] Furthermore, the surface of the diffusion layer is coated with a quantum dot layer by spin coating or inkjet printing. The quantum dot layer is prepared by red and green quantum dots, resin and scattering particles, etc. The red and green quantum dots used are CdSe / ZnS core-shell structures, and the scattering particles are nano-organic transparent microspheres.

[0020] Furthermore, in the method, the GaN chip with the sapphire substrate removed is transferred onto a blue film and expanded into a specific spacing using the blue film. Then, the GaN chip is aligned and bonded to a substrate coated with an organosilicon protective layer, wherein the light-emitting surface of the GaN chip is in contact with the organosilicon protective layer.

[0021] Furthermore, the white wall adhesive comprises organic resin and white titanium dioxide, wherein the mass ratio of titanium dioxide to resin is between 1:1 and 2:1.

[0022] In a second aspect, the present invention provides a sub-millimeter light-emitting diode, which is prepared by the sub-millimeter light-emitting diode preparation method described in the first aspect, and the sub-millimeter light-emitting diode is used in the production of Mini LED or Micro LED backlight products.

[0023] The beneficial effects of this invention are as follows:

[0024] This invention achieves a high color gamut without the need for expensive quantum dot films and facilitates the thinning and lightening of backlight modules. It reduces production costs while delivering high-quality color effects and a thinner backlight module, making the product more portable and compact.

[0025] This invention achieves high reliability by employing an alternating approach of inorganic and organic materials to encapsulate and protect the quantum dot layer. It effectively protects the quantum dot layer from external environmental influences, thereby improving the stability and reliability of the device.

[0026] This invention introduces an inorganic DBR layer, which can improve the luminous brightness of the device. The inorganic DBR layer can effectively reflect and scatter light, allowing more light to escape from the device, thereby enhancing the luminous brightness of the device.

[0027] This invention uses white dividing barriers to separate the chips, which can effectively separate the chips, reduce interference between them, reduce light leakage inside the chips, and improve the luminous efficiency and visual effect of the device.

[0028] This invention is highly compatible with existing Mini LED die bonding equipment, requiring no modification and allowing for easy gripping and transfer. This means that existing Mini LED die bonding equipment can be used for production without any alterations, thereby reducing production costs and increasing efficiency. Simultaneously, this compatibility ensures production stability and reliability. Attached Figure Description

[0029] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0030] Figure 1 This is a flowchart of the fabrication method for sub-millimeter light-emitting diodes;

[0031] Figure 2 A schematic diagram of a substrate covered with a pyrolysis film;

[0032] Figure 3 This is a schematic diagram showing the DBR layer after it has been prepared on the pyrolysis film.

[0033] Figure 4 This is a schematic diagram showing the light diffusion layer fabricated on the DBR.

[0034] Figure 5 This is a schematic diagram showing the quantum dot layer fabricated on the light diffusion layer.

[0035] Figure 6 This is a schematic diagram showing the preparation of an organosilicon protective layer on a quantum dot layer.

[0036] Figure 7 This is a schematic diagram showing the chips after alignment and bonding, with white separator walls filled between the chips.

[0037] Figure 8 This is a schematic diagram showing the process after etching the trench and depositing silicon nitride on the sidewalls.

[0038] The labels in the attached diagram represent:

[0039] 1: Substrate, 2: Pyrolytic film, 3: DBR layer, 4: Light diffusion layer, 5: Quantum dot layer, 6: Silicone protective layer, 7: GaN chip, 8: White separator wall, 9: Silicon nitride layer. Detailed Implementation

[0040] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0041] Reference Figure 1 As shown, this embodiment provides a method for fabricating a sub-millimeter light-emitting diode, including the following steps:

[0042] A distributed Bragg reflector, a diffusion layer, a quantum dot layer, and an organosilicon protective layer are sequentially disposed on a substrate covered with a pyrolysis film.

[0043] The GaN chip is expanded into a specific spacing by using a blue film, and then the GaN chip is aligned and bonded to a substrate coated with an organosilicon protective layer.

[0044] White wall adhesive is filled between the channels of GaN chips, and the separation barrier, silicone protective layer, quantum dot layer, diffusion layer and DBR layer between GaN chips are etched out to form the channels.

[0045] Sub-millimeter light-emitting diodes are obtained by depositing a silicon nitride layer on the sidewall surface of the channel through ALD or PECVD.

[0046] As a preferred embodiment, the substrate is either a glass substrate or a silicon substrate, and in this embodiment, the substrate surface has a thermally degradable film (see reference). Figure 2 As shown in the figure, the adhesiveness of the pyrolysis film gradually decreases upon heating.

[0047] In one embodiment, reference is made to Figure 3 As shown, a DBR distributed Bragg reflector is fabricated on a substrate covered with a pyrolysis film.

[0048] Furthermore, the DBR distributed Bragg reflector layer was prepared using PECVD plasma chemical vapor deposition.

[0049] As a preferred embodiment, the DBR distributed Bragg reflector is made of two inorganic materials with different refractive indices, which can provide effective water and oxygen barrier and improve the brightness of the quantum dot light-emitting diode device of the present invention.

[0050] In one embodiment, reference is made to Figure 4 As shown, a diffusion layer is coated on the surface of the DBR distributed Bragg mirror.

[0051] As a preferred embodiment, the diffusion layer mainly includes organic resin materials, organic diffusion particles, organic solvents, additives, etc.

[0052] As a preferred embodiment, the resin material is one or more of acrylic resin, silicone resin, epoxy resin, and polyvinyl chloride resin.

[0053] As a preferred embodiment, the diffused particles are one or more of PMMA (polymethyl methacrylate), PBMA (polybutyl methacrylate), PA (nylon), and PU (polyurethane).

[0054] In this embodiment, the average particle size of the diffused particles is between 1-15 μm, and the additive has a leveling effect. The thickness of the diffused layer is between 30-60 μm, which can diffuse light and make the chip emit light more uniformly.

[0055] In one embodiment, reference is made to Figure 5 As shown, the surface of the diffusion layer is coated with quantum dot layers by spin coating or inkjet printing.

[0056] As a preferred embodiment, the quantum dot layer is prepared from red and green quantum dots, resin, and scattering particles.

[0057] Furthermore, the red and green quantum dots used have a CdSe / ZnS core-shell structure with center wavelengths of 630nm and 535nm, respectively, and the scattering particles are nano-organic transparent microspheres.

[0058] In one embodiment, reference is made to Figure 6 As shown, an organosilicon protective layer is coated on the surface of the quantum dot layer. This layer has a certain water and oxygen barrier effect, and on the other hand, it creates a certain gap between the quantum dot layer and the chip layer, preventing blue light from directly contacting the quantum dot layer and improving the service life of the quantum dot material. The thickness of the organosilicon protective layer is between 30-60um.

[0059] In one embodiment, reference is made to Figure 7 As shown, the GaN (gallium nitride) chip with the sapphire substrate removed is transferred onto the blue film and expanded into a specific spacing through the blue film. Then, the GaN chip is aligned and bonded to a substrate coated with an organosilicon protective layer, with the light-emitting surface of the chip in contact with the organosilicon protective layer.

[0060] In one embodiment, planarization is achieved by filling the channels of the chip with white wall adhesive.

[0061] As a preferred embodiment, the white wall adhesive is mainly composed of organic resin and white titanium dioxide, wherein the mass ratio of titanium dioxide to resin is between 1:1 and 2:1. The blocking and reflection effects of the white partition wall are used to reduce light leakage from the chip and light crosstalk between chips.

[0062] In one embodiment, reference is made to Figure 8 As shown, the partition walls, silicone protective layer, quantum dot layer, diffusion layer and DBR layer between chips are etched into channels by etching process, and then silicon nitride layer is deposited on the sidewall by ALD or PECVD method to enhance the water and oxygen barrier effect of the material side.

[0063] At the implementation level, this embodiment provides a method for fabricating sub-millimeter light-emitting diodes, including the following steps:

[0064] a. Substrate selection: Either a glass substrate or a silicon substrate is selected. In this embodiment, a glass substrate is selected. The surface of the substrate is covered with a pyrolytic film. The adhesion of the pyrolytic film gradually decreases when heated.

[0065] b. DBR layer fabrication: A DBR distributed Bragg mirror is fabricated on a substrate covered with a pyrolysis film. The DBR distributed Bragg mirror is fabricated using PECVD plasma chemical vapor deposition.

[0066] c. Preparation of light diffusion layer: A light diffusion layer is coated on the surface of the DBR distributed Bragg mirror. The light diffusion layer mainly includes organic resin material, organic diffusion particles, organic solvent, additives, etc.

[0067] d. Quantum dot layer preparation: The quantum dot layer is coated on the surface of the light diffusion layer by spin coating or inkjet printing. The quantum dot layer is prepared by red and green quantum dots, resin and scattering particles, etc.

[0068] e. Protective layer preparation: A layer of organosilicon protective layer is coated on the surface of the quantum dot layer. This layer has a certain water and oxygen barrier effect, and on the other hand, it forms a certain gap between the quantum dot layer and the chip layer, preventing blue light from directly contacting the quantum dot layer and improving the service life of the quantum dot material.

[0069] f. Chip bonding and white wall fabrication: The GaN (gallium nitride) chip with the sapphire substrate removed is transferred onto the blue film and expanded to a specific spacing through the blue film. Then, the GaN chip is aligned and bonded to the substrate coated with an organosilicon protective layer. Finally, white wall adhesive is filled between the channels of the chip to achieve planarization.

[0070] g. Sidewall silicon nitride deposition: Through etching, channels are etched out between the chip partition walls, silicone protective layer, quantum dot layer, diffusion layer and DBR layer. Then, silicon nitride layer is deposited on the sidewall by ALD or PECVD to enhance the water and oxygen barrier effect of the material sidewall.

[0071] This embodiment can directly emit high-quality white light, which can improve the display effect and is suitable for Mini LED display-related fields. The device uses an alternating inorganic-organic material composite method to achieve encapsulation and protection of the quantum dot layer, which has a strong barrier effect against water and oxygen.

[0072] In one embodiment, a sub-millimeter light-emitting diode (LED) is provided, which is prepared by a sub-millimeter LED fabrication method and is used in the production of Mini LED or Micro LED backlight products.

[0073] In summary, this invention achieves a high color gamut without the need for expensive quantum dot films and facilitates the thinning and lightening of backlight modules. It reduces production costs while achieving high-quality color effects and a thinner backlight module, making the product more portable and compact.

[0074] This invention achieves high reliability by employing an alternating approach of inorganic and organic materials to encapsulate and protect the quantum dot layer. It effectively protects the quantum dot layer from external environmental influences, thereby improving the stability and reliability of the device.

[0075] This invention introduces an inorganic DBR layer, which can improve the luminous brightness of the device. The inorganic DBR layer can effectively reflect and scatter light, allowing more light to escape from the device, thereby enhancing the luminous brightness of the device.

[0076] This invention uses white dividing barriers to separate the chips, which can effectively separate the chips, reduce interference between them, reduce light leakage inside the chips, and improve the luminous efficiency and visual effect of the device.

[0077] This invention is highly compatible with existing Mini LED die bonding equipment, requiring no modification and allowing for easy gripping and transfer. This means that existing Mini LED die bonding equipment can be used for production without any alterations, thereby reducing production costs and increasing efficiency. Simultaneously, this compatibility ensures production stability and reliability.

[0078] The above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit it. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for fabricating a sub-millimeter light-emitting diode, characterized in that, The method includes the following steps: A distributed Bragg reflector, a diffusion layer, a quantum dot layer, and an organosilicon protective layer are sequentially disposed on a substrate covered with a pyrolysis film. The GaN chips are expanded to a predetermined spacing using a blue film, and then the GaN chips are aligned and bonded to a substrate coated with an organosilicon protective layer. White wall adhesive is filled between the channels of GaN chips, and the separation barrier, silicone protective layer, quantum dot layer, diffusion layer and DBR layer between GaN chips are etched out to form the channels. Sub-millimeter light-emitting diodes are obtained by depositing silicon nitride layers on the sidewall surface of the channel using ALD or PECVD.

2. The method for fabricating a sub-millimeter light-emitting diode according to claim 1, characterized in that, The substrate is either a glass substrate or a silicon substrate.

3. The method for fabricating a sub-millimeter light-emitting diode according to claim 1, characterized in that, The distributed Bragg reflector is prepared by plasma chemical vapor deposition and contains two inorganic materials with different refractive indices.

4. The method for fabricating a sub-millimeter light-emitting diode according to claim 1, characterized in that, The thickness of the organosilicon protective layer is 30-60 μm, and the thickness of the diffusion layer is 30-60 μm. The diffusion layer includes an organic resin material, organic diffusion particles, an organic solvent, and additives.

5. The method for fabricating a sub-millimeter light-emitting diode according to claim 4, characterized in that, The resin material is one or more of acrylic resin, silicone resin, epoxy resin, and polyvinyl chloride resin; The diffused particles are one or more of PMMA (polymethyl methacrylate), PBMA (polybutyl methacrylate), PA (nylon), and PU (polyurethane).

6. The method for fabricating a sub-millimeter light-emitting diode according to claim 4, characterized in that, The average particle size of the organic diffusion particles is between 1 and 15 μm, and the additives serve a leveling function.

7. The method for fabricating a sub-millimeter light-emitting diode according to claim 1, characterized in that, The surface of the diffusion layer is coated with a quantum dot layer by spin coating or inkjet printing. The quantum dot layer is prepared by red and green quantum dots, resin and scattering particles. The red and green quantum dots used are CdSe / ZnS core-shell structures, and the scattering particles are nano-organic transparent microspheres.

8. The method for fabricating a sub-millimeter light-emitting diode according to claim 1, characterized in that, In the method, the GaN chip with the sapphire substrate removed is transferred to a blue film and expanded to a specific distance through the blue film. Then, the GaN chip is aligned and bonded to a substrate coated with an organosilicon protective layer, wherein the light-emitting surface of the GaN chip is in contact with the organosilicon protective layer.

9. The method for fabricating a sub-millimeter light-emitting diode according to claim 1, characterized in that, The white wall adhesive comprises organic resin and white titanium dioxide, wherein the mass ratio of titanium dioxide to resin is between 1:1 and 2:

1.

10. A sub-millimeter light-emitting diode, prepared by the sub-millimeter light-emitting diode preparation method according to any one of claims 1-9, characterized in that, The sub-millimeter light-emitting diodes are used in the production of Mini LED or Micro LED backlight products.

Images