A Micro LED display chip and preparation method thereof

Abstract

The present invention relates to the technical field of display chips, and discloses a Micro LED display chip and a preparation method thereof. The Micro LED display chip comprises a driving substrate, a plurality of light-emitting units are arranged on the surface of the driving substrate, the bottom of the light-emitting unit is connected to the driving substrate through a bonding metal layer, the light-emitting unit comprises an epitaxial layer, a dielectric layer is arranged on the side wall of the epitaxial layer, a window is opened in the dielectric layer corresponding to the light outlet of the light-emitting unit, a nano silver wire layer is arranged outside the dielectric layer, and an ITO conductive film is deposited in the nano silver wire layer. The present invention enhances the heat dissipation capacity of the Micro LED and improves the thermal stability by introducing a mesh nano silver wire segmented electrode structure.

Description

Technical Field

[0001] The present invention belongs to the technical field of display chips, and specifically relates to a Micro LED display chip and a preparation method thereof. Background Art

[0002] The full name of Micro LED is Micro Light Emitting Diode, which is also called micro-light-emitting diode in Chinese. It can also be written as μLED. It generally refers to the technology of using LED light-emitting units with a size of 1~60um to form a display array. Its size is equivalent to 1 / 10 of a human hair. It has the characteristics of no backlight, high photoelectric conversion efficiency, and response time in the ns level. It is a technology that makes LED thin-film, miniaturized and arrayed, so that its volume is only 1% of the size of mainstream LEDs, and the pixel distance is from millimeters to microns. As an emerging display technology, Micro LED has the advantages of high resolution, low power consumption, high brightness and fast response time. Therefore, it has important application value in the fields of high-resolution display, wearable devices, augmented reality and high-speed visible light communication. MicroLED not only inherits the advantages of high efficiency, high brightness, high reliability and fast response time of traditional LED, but also has the characteristics of energy saving, simple structure, small size, thinness and no need for backlight source.

[0003] In the application process, the bottom layer of Micro LED is made into LED display drive circuit using normal CMOS integrated circuit manufacturing process, and then the LED array is made on the integrated circuit using MOCVD machine, thus realizing a micro display screen, which is also called a smaller version of LED display screen. As the size of Micro LED display chip decreases, its brightness requirement is also higher, and the corresponding heat generation power is greater. The existing Micro LED structure has poor heat dissipation and poor stability, which in turn affects the reliability of the device. Summary of the invention

[0004] In order to solve the deficiencies mentioned in the above background technology, the purpose of the present invention is to provide a Micro LED display chip and a preparation method thereof, which enhances the heat dissipation capacity of the Micro LED and improves the thermal stability by introducing a mesh nano silver wire segmented electrode structure.

[0005] The purpose of the present invention can be achieved through the following technical solutions:

[0006] A Micro LED display chip includes a driving substrate. A plurality of light-emitting units are arranged on the surface of the driving substrate. The bottom of the light-emitting unit is connected to the driving substrate through a bonding metal layer. The light-emitting unit includes an epitaxial layer. A dielectric layer is arranged on the side wall of the epitaxial layer. The dielectric layer has a window corresponding to a light outlet of the light-emitting unit. A nano silver wire layer is arranged outside the dielectric layer. An ITO conductive film is deposited inside the nano silver wire layer.

[0007] Further preferably, the driving substrate is a silicon-based CMOS backplane, and a surface of the driving substrate is provided with metal contacts corresponding to the epitaxy.

[0008] Further preferably, the epitaxial layer includes a first semiconductor layer, a multi-quantum well structure and a second semiconductor layer, and the first semiconductor layer and the second semiconductor layer are one or more of ZnSe, ZnO, GaN, AlN, InN, InGaN, GaP, AlInGaP, and AlGaAs.

[0009] Further preferably, the nano silver wire layer is in a grid shape with a density uniformity within 20%, and the nano silver wire layer is prepared by a hydrothermal method or a seed crystal method.

[0010] Further preferably, the dielectric layer is made of SiO2, Si3N4 or Al2O3 material.

[0011] A method for preparing a Micro LED display chip comprises the following steps:

[0012] S1, coating the first metal layer and the second metal layer on the surface of the epitaxial wafer and the driving substrate respectively by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating;

[0013] S2, bonding the coated epitaxial wafer and the driving substrate, bonding the first metal layer and the second metal layer to obtain a bonding metal layer, forming a good ohmic contact, and removing the epitaxial wafer substrate and the buffer layer by mechanical grinding or etching;

[0014] S3, preparing a mask pattern on the surface of the epitaxial layer by photolithography and etching, then etching the epitaxial layer to obtain a number of independent light-emitting unit epitaxial layers, and continuing to etch the bonding metal layer to connect each light-emitting unit epitaxial layer to the corresponding metal contact of the driving substrate;

[0015] S4, depositing a dielectric layer material on the surface of the epitaxial layer to form a dielectric layer, and then opening a window at the light outlet at the top of the corresponding light-emitting unit by etching;

[0016] S5. Prepare a grid-like nano silver wire layer on the surface of the dielectric layer by a hydrothermal method or a seed crystal method, and then deposit an ITO conductive film in the grid of the nano silver wire layer to complete the preparation of the Micro LED display chip.

[0017] Further preferably, the epitaxial wafer comprises a substrate, a buffer layer and an epitaxial layer, the substrate is a silicon-based substrate or a sapphire substrate, and the buffer layer is SiO2, Al2O3, Si3N4, GaN or SiC material.

[0018] More preferably, the mask is polyimide or polytetrafluoroethylene.

[0019] Beneficial effects of the present invention:

[0020] The present invention divides the traditional oxide transparent electrode by introducing a nanosilver mesh structure with high electrical conductivity and excellent thermal conductivity. The new structure has the characteristics of improving transmittance, increasing thermal conductivity and reducing resistivity, ultimately reducing the thermal effect of the device and increasing the service life of the device. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, for ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0022] Figure 1 Schematic diagram of the front projection of the Micro LED display chip of the present invention;

[0023] Figure 2 It is a process flow diagram of step S1 of the present invention;

[0024] Figure 3 It is a schematic diagram of the process flow of step S2 of the present invention;

[0025] Figure 4 It is a process flow diagram of step S3 of the present invention;

[0026] Figure 5 It is a process flow diagram of step S4 of the present invention;

[0027] Figure 6 It is a schematic diagram of the process flow of step S5 of the present invention.

[0028] In the figure: 1-substrate, 2-buffer layer, 3-epitaxial layer, 4-first semiconductor layer, 5-multi-quantum well structure, 6-second semiconductor layer, 7-driving substrate, 8-bonding metal layer, 801-first metal layer, 802-second metal layer, 9-dielectric layer, 10-nanosilver wire layer, 11-ITO conductive film. DETAILED DESCRIPTION

[0029] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. 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 creative work are within the scope of protection of the present invention.

[0030] like Figure 1 As shown, the present invention provides a Micro LED display chip, including a driving substrate 7, a plurality of light-emitting units are arranged on the surface of the driving substrate 7, the bottom of the light-emitting unit is connected to the driving substrate 7 through a bonding metal layer 8, the light-emitting unit includes an epitaxial layer 3, a dielectric layer 9 is arranged on the side wall of the epitaxial layer 3, the dielectric layer 9 has a window corresponding to the light outlet of the light-emitting unit, a nano silver wire layer 10 is arranged outside the dielectric layer 9, and an ITO conductive film 11 is deposited inside the nano silver wire layer 10.

[0031] The driving substrate 7 is a silicon-based CMOS backplane, and a metal contact corresponding to the epitaxial layer 3 is provided on the surface of the driving substrate 7; the epitaxial layer includes a first semiconductor layer, a multi-quantum well structure, and a second semiconductor layer, wherein the first semiconductor layer and the second semiconductor layer correspond to an N-type semiconductor and a P-type semiconductor, respectively, and the material may be ZnSe, ZnO, GaN, AlN, InN, InGaN, GaP, AlInGaP or AlGaAs; the dielectric layer may be SiO2, Si3N4 or Al2O3 material.

[0032] The silver nanowire layer 10 is in a grid shape and is prepared by a hydrothermal method or a seed crystal method. The line width of the silver nanowire layer 10 is 10-50 nm. The silver nanowire layer 10 can be arranged in a disordered manner with a density uniformity within 20% to avoid affecting the brightness uniformity.

[0033] like Figures 2 to 6 As shown, the method for preparing the above-mentioned Micro LED display chip includes the following steps:

[0034] S1, coating the first metal layer 801 and the second metal layer 802 on the surface of the epitaxial wafer and the driving substrate 7 respectively by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating;

[0035] S2, bonding the coated epitaxial wafer and the driving substrate 7, bonding the first metal layer 801 and the second metal layer 802 to obtain a bonding metal layer 8, forming a good ohmic contact, and removing the epitaxial wafer substrate 1 and the buffer layer 2 by mechanical grinding or etching;

[0036] S3, preparing a mask 12 pattern on the surface of the epitaxial layer 3 by photolithography and etching, then etching the epitaxial layer 3 to obtain a number of independent light-emitting unit epitaxial layers 3, and continuing to etch the bonding metal layer 8 to connect each light-emitting unit epitaxial layer 3 with the corresponding metal contact of the driving substrate 7;

[0037] S4, depositing a dielectric layer material on the surface of the epitaxial layer to form a dielectric layer 9, and then opening a window at the light outlet at the top of the corresponding light-emitting unit by etching;

[0038] S5. Prepare a grid-shaped nano silver wire layer 10 on the surface of the dielectric layer 9 by a hydrothermal method or a seed crystal method, and then deposit an ITO conductive film 11 in the grid of the nano silver wire layer 10 to complete the preparation of the Micro LED display chip.

[0039] Among them, the epitaxial wafer includes a substrate 1, a buffer layer 2 and an epitaxial layer 3. The substrate 1 is a silicon-based substrate or a sapphire substrate, the buffer layer 2 is SiO2, Al2O3, Si3N4, GaN or SiC material, and the mask is a high-temperature material such as polyimide and polytetrafluoroethylene, which can withstand corrosion from high temperatures and organic solvents.

[0040] In the description of this specification, the description with reference to the terms "one embodiment", "example", "specific example", etc. means that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner.

[0041] The above shows and describes the basic principles, main features and advantages of the present invention. Those skilled in the art should understand that the present invention is not limited to the above embodiments, and the above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, and these changes and improvements all fall within the scope of the present invention to be protected.

Claims

1. A Micro LED display chip, characterized in that: It comprises a driving substrate, a plurality of light-emitting units are arranged on the surface of the driving substrate, the bottom of the light-emitting unit is connected to the driving substrate through a bonding metal layer, the light-emitting unit comprises an epitaxial layer, a dielectric layer is arranged on the side wall of the epitaxial layer, a window is opened in the dielectric layer corresponding to the light outlet of the light-emitting unit, a nano silver wire layer is arranged outside the dielectric layer, the nano silver wire layer is in a grid shape, the line width is 10-50nm, the density uniformity is within 20%, and an ITO conductive film is deposited in the nano silver wire layer.

2. The Micro LED display chip according to claim 1, characterized in that: The driving substrate is a silicon-based CMOS backplane, and the surface of the driving substrate is provided with metal contacts corresponding to the epitaxial layer.

3. The Micro LED display chip according to claim 1, characterized in that: The epitaxial layer includes a first semiconductor layer, a multi-quantum well structure, and a second semiconductor layer, wherein the first semiconductor layer and the second semiconductor layer are one or more of ZnSe, ZnO, GaN, AlN, InN, InGaN, GaP, AlInGaP, and AlGaAs.

4. The Micro LED display chip according to claim 1, characterized in that: The nano silver wire layer is prepared by a hydrothermal method or a seed crystal method.

5. The Micro LED display chip according to claim 1, characterized in that: The dielectric layer is made of SiO2, Si3N4 or Al2O3 material.

6. The method for preparing a Micro LED display chip according to any one of claims 1 to 5, characterized in that: The following steps are involved: S1, coating the first metal layer and the second metal layer on the surface of the epitaxial wafer and the driving substrate respectively by vacuum evaporation coating, vacuum sputtering coating or vacuum ion coating; S2, bonding the coated epitaxial wafer and the driving substrate, bonding the first metal layer and the second metal layer to obtain a bonding metal layer, forming a good ohmic contact, and removing the epitaxial wafer substrate and the buffer layer by mechanical grinding or etching; S3, preparing a mask pattern on the surface of the epitaxial layer by photolithography and etching, then etching the epitaxial layer to obtain a number of independent light-emitting unit epitaxial layers, and continuing to etch the bonding metal layer to connect each light-emitting unit epitaxial layer to the corresponding metal contact of the driving substrate; S4, depositing a dielectric layer material on the surface of the epitaxial layer to form a dielectric layer, and then opening a window at the light outlet at the top of the corresponding light-emitting unit by etching; S5. Prepare a grid-shaped nano silver wire layer on the surface of the dielectric layer by a hydrothermal method or a seed crystal method, and then deposit an ITO conductive film in the grid of the nano silver wire layer to complete the preparation of the Micro LED display chip.

7. The method for preparing a Micro LED display chip according to claim 6, characterized in that: The epitaxial wafer comprises a substrate, a buffer layer and an epitaxial layer, the substrate is a silicon-based substrate or a sapphire substrate, and the buffer layer is made of SiO2, Al2O3, Si3N4, GaN or SiC material.

8. The method for preparing a Micro LED display chip according to claim 6, wherein: The mask is made of polyimide or polytetrafluoroethylene.

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