Micro-LED micro display chip and preparation method thereof

Abstract

The invention discloses a Micro-LED micro display chip and a preparation method thereof, and relates to the technical field of micro display. The Micro-LED micro display chip comprises a driving panel, a plurality of LED chips and a plurality of LED chips, the plurality of LED units are arranged on the driving panel, the plurality of LED units are provided with a plurality of LED table boards which are in one-to-one correspondence, and each LED unit can be independently driven by the driving panel; the grid structure is provided with a plurality of grid holes, the plurality of grid holes are respectively arranged around the plurality of LED table boards, and concave areas are formed between the LED table boards and the corresponding grid holes; the lens unit is arranged in the concave area and located above the LED unit. And the wavelength conversion layer comprises a plurality of wavelength conversion units, and the plurality of wavelength conversion units are arranged above the lens unit. According to the Micro-LED micro display chip, the absorbance and the conversion lighting effect of the wavelength conversion layer can be improved, the light emitting purity of a pixel area is guaranteed, and the screen color gamut and the color purity of a display are improved.

Description

Technical Field

[0001] The present invention relates to the field of micro-display technology, and in particular to a Micro-LED micro-display chip and a preparation method thereof. Background Art

[0002] Micro-LED, also known as micro light-emitting diode, refers to a high-density integrated LED array. The distance between LED pixels in the array is in the order of 0.1-100 microns, and each LED pixel can emit light by itself. At present, Micro-LED micro display chips are widely used in various cutting-edge fields such as augmented reality (AR), near-eye display (NED) and wearable display due to their small size, long life, fast response speed and low power consumption.

[0003] In the construction process of traditional Micro-LED micro-display chips, the quantum dot film layer shows obvious incomplete absorption problems due to thickness limitations and the influence of the film layer's own structure, which leads to insufficient color purity of the generated display. This not only affects the color performance of the Micro-LED display, but also limits its application in high-demand display fields. Summary of the invention

[0004] In view of this, the present invention provides a Micro-LED micro display chip, the main purpose of which is to solve the technical problem of insufficient color purity of Micro-LED displays.

[0005] According to a first aspect of the present invention, there is provided a Micro-LED micro display chip, comprising:

[0006] Driver panel;

[0007] A plurality of LED units are arranged on the driving panel, the plurality of LED units have a plurality of LED tables corresponding to each other, and each of the LED units can be driven individually by the driving panel;

[0008] A grid structure having a plurality of grid holes, wherein the plurality of grid holes are respectively arranged around the plurality of LED countertops, and a recessed area is formed between the LED countertops and the corresponding grid holes;

[0009] A lens unit is disposed in the recessed area and located above the LED unit;

[0010] The wavelength conversion layer includes a plurality of wavelength conversion units, and the plurality of wavelength conversion units are arranged above the lens unit.

[0011] According to a second aspect of the present invention, a method for preparing a Micro-LED micro display chip is provided, the method comprising:

[0012] Providing a drive panel;

[0013] A plurality of LED units are formed on the driving panel, wherein the plurality of LED units have a plurality of LED tables corresponding to each other, and each of the LED units can be driven individually by the driving panel;

[0014] forming a grid structure having a plurality of grid holes, wherein the plurality of grid holes are respectively arranged around the plurality of LED countertops, and a recessed area is formed between the LED countertops and the corresponding grid holes;

[0015] forming a lens unit above the LED unit in the recessed area;

[0016] A wavelength conversion layer is formed above the lens unit, wherein the wavelength conversion layer includes a plurality of wavelength conversion units.

[0017] The present invention provides a Micro-LED micro display chip and a preparation method thereof. The Micro-LED micro display chip includes a driving panel, a plurality of LED units, a grid structure, a lens unit and a wavelength conversion layer. The Micro-LED micro display chip can fully transmit the light emitted by the LED unit by setting a lens unit between the LED unit and the wavelength conversion layer, thereby optimizing the light path and increasing the light gathering effect, thereby improving the absorbance and conversion light efficiency of the wavelength conversion layer, ensuring the purity of the light emitted from the pixel area, and improving the screen color gamut and color purity of the Micro-LED display.

[0018] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] The drawings described herein are used to provide a further understanding of the present invention and constitute a part of the present invention. The exemplary embodiments of the present invention and their descriptions are used to explain the present invention and do not constitute an improper limitation of the present invention. In the drawings:

[0020] Figure 1 A schematic cross-sectional structure diagram of a Micro-LED micro display chip provided by an embodiment of the present invention is shown;

[0021] Figure 2 A schematic cross-sectional structure diagram of another Micro-LED micro display chip provided by an embodiment of the present invention is shown;

[0022] Figure 3 A schematic diagram of a process for preparing a Micro-LED micro display chip provided by an embodiment of the present invention is shown;

[0023] Figure 4 A schematic cross-sectional structure diagram of a driving panel and a plurality of LED units provided in an embodiment of the present invention is shown;

[0024] Figure 5 Shown in Figure 4 A schematic cross-sectional structure diagram of an etching stop layer formed on a plurality of LED units shown;

[0025] Figure 6 Shown in Figure 5 A schematic cross-sectional structure diagram of a grid structure formed on an etch stop layer shown;

[0026] Figure 7 Shown in Figure 6 A schematic diagram of the cross-sectional structure of the grid structure and the metal reflective layer coated on the multiple LED units shown;

[0027] Figure 8 Shows the Figure 7 The schematic diagram of the cross-sectional structure of the metal reflective layer formed by etching the reflective layer is shown;

[0028] Fig. 9 Shown in Figure 8 A schematic cross-sectional structure diagram of a first transparent material being filled in a recessed area formed between the grid structure and the LED table;

[0029] Fig.10 Shows the Fig. 9 The schematic cross-sectional structure diagram of the lens unit formed by the reflow treatment of the first transparent material shown;

[0030] Fig.11 Shown in Fig.10 The schematic cross-sectional structure diagram of the lens unit filled with a second transparent material to form a filled structure;

[0031] Fig.12 Shown in Fig.11 A schematic cross-sectional structure diagram of a wavelength conversion layer formed by filling a wavelength conversion material on the fill-in structure shown;

[0032] Fig.13 Shown in Fig.12 A schematic cross-sectional structure diagram of a wavelength conversion layer coated with a reflector material is shown;

[0033] Fig.14 Shows the Fig.13 A schematic diagram of a cross-sectional structure of a reflector material subjected to graphical processing;

[0034] Fig.15 Shows the Fig.14 The cross-sectional structure diagram of the transflective layer is obtained by exposing and developing the pattern shown in FIG.

[0035] Fig.16 Shown in Fig.15 A schematic cross-sectional structure diagram of a light filter layer disposed on a transmissive reflective layer is shown;

[0036] Fig.17 A schematic diagram showing a reflection curve and spectrum of a transmissive reflective layer provided by an embodiment of the present invention is shown;

[0037] Fig.18 A schematic diagram of a reflection curve and spectrum of a reflective structure formed by a lens unit and a filling unit provided in an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0038] The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all of the embodiments.

[0039] It should be noted that, in the description of the present application, the meaning of the terms "on", "above", "above", and "above" should be interpreted in the broadest sense, meaning that the description containing these terms is interpreted as "the component can be set on another component in direct contact, or there can be an intermediate component or layer between the components". In addition, for the convenience of description, the present application may also use spatial relative terms such as "under", "below", "under", "on", "above", "above", "lower", "upper", etc. to describe the relationship between an element or component and another element or component shown in the drawings. In addition to the orientations described in the figures, the spatially relative terms are also intended to cover different orientations of the device in use or operation. The device can be oriented in other ways (rotated 90° or in other orientations), and the spatially relative descriptors used in the present application can be interpreted accordingly.

[0040] The term "layer" as used in this application refers to a portion of a material that includes an area having a certain thickness. A layer may extend over the entire underlying or superstructure, or may extend over a localized area of ​​the underlying or superstructure. In addition, a layer may be an area of ​​a homogeneous or inhomogeneous continuous structure whose thickness is less than the thickness of the continuous structure. For example, a layer may be located between the top and bottom surfaces of the continuous structure or between any pair of horizontal planes therebetween. A layer may extend horizontally, vertically and / or along a tapered surface.

[0041] At present, in the field of Micro-LED micro-display technology, especially in the technology of using quantum dot film layer (Quantum Dot Layer, QDL) to achieve full-color display, there are many technical challenges and limitations. In the construction process of traditional Micro-LED micro-display chips, the quantum dot film layer shows obvious incomplete absorption problems due to thickness limitations and the influence of the film layer's own structure, which directly leads to the problem of insufficient color purity of the display. The main reasons are as follows:

[0042] First, the quantum dot materials currently used have limitations in terms of absorption spectral characteristics. Their absorption efficiency is low and they cannot effectively convert the incident LED light source into the desired narrow-bandwidth color output, which in turn reduces the color saturation and accuracy. Secondly, the interface reflectivity between the light-emitting surface of the LED and the quantum dot film layer is high, which means that a considerable portion of the light emitted by the LED does not successfully penetrate the quantum dot layer, but is reflected back by the interface and fails to be effectively converted into light of the desired color, resulting in energy waste. Furthermore, due to the physical properties of the quantum dot film layer itself, there is a certain amount of reverse light loss, that is, part of the energy absorbed by the quantum dots is not effectively scattered toward the front of the display, but is dissipated toward the back, which also seriously affects the overall display efficiency and color purity.

[0043] Based on this, the quantum dot film layer of the current Micro-LED micro display chip has limitations in thickness, material absorption performance, and light path management. Therefore, after integrating the quantum dot film layer, the Micro-LED micro display chip often finds it difficult to achieve the ideal full-color LED color purity level. In order to overcome the above problems and improve the color quality and display efficiency of the Micro-LED micro display device, this embodiment proposes a Micro-LED micro display chip and a preparation method thereof. Figures 1 to 18 The Micro-LED micro display chip and the preparation method thereof according to some embodiments of the present invention are described.

[0044] In one embodiment, a Micro-LED micro display chip is proposed, and the Micro-LED micro display chip includes: a driving panel; a plurality of LED units, arranged on the driving panel, the plurality of LED units having a plurality of LED tables corresponding to each other, and each LED unit can be driven individually by the driving panel; a grid structure having a plurality of grid holes, the plurality of grid holes are respectively arranged around the plurality of LED tables, and a recessed area is formed between the LED tables and the corresponding grid holes; a lens unit, arranged in the recessed area and located above the LED unit; a wavelength conversion layer, including a plurality of wavelength conversion units, and the plurality of wavelength conversion units are arranged above the lens unit.

[0045] Specifically, Figure 1A possible cross-sectional structure diagram of a Micro-LED micro display chip provided in this embodiment. Figure 1 As shown, the Micro-LED micro display chip may include a driving panel 101, a plurality of LED units 102, a fence structure 109 having a plurality of grid holes, a lens unit 111, and a wavelength conversion layer composed of a plurality of wavelength conversion units 113, 114, and 115. The plurality of LED units 102 may be arranged on the driving panel 101 in a regular or irregular manner as pixels of the Micro-LED micro display chip. Furthermore, the plurality of LED units 102 may have a plurality of LED tables corresponding to the plurality of LED units 102 one by one, and the LED unit 102 may also be referred to as a Micro-LED unit, and the size of the LED unit 102 is 0.1-10 microns.

[0046] In some embodiments, the LED unit 102 may be a micro light emitting diode or a micro organic light emitting diode, wherein the micro light emitting diode is formed based on an inorganic semiconductor material. For example, the inorganic semiconductor material may be gallium nitride, aluminum gallium nitrogen, gallium arsenide, aluminum gallium indium phosphide, etc., and the micro organic light emitting diode is formed based on an organic material, for example, the organic material may be a small molecule, a polymer, a phosphorescent material, etc. Each LED unit 102 may emit a first color light, and the color of the first color light includes but is not limited to: any one of red light, green light, blue light, yellow light, or ultraviolet light.

[0047] In some embodiments, the plurality of LED tables may be in a trapezoidal structure. The side wall of the LED table may be an inclined surface, and the angle between the side wall of the LED table and the top surface may be an obtuse angle, thereby improving the focusing effect of the LED unit. It should be understood that the plurality of LED tables may also be in a columnar structure, in which case the angle between the side wall of the LED table and the top surface is a right angle.

[0048] Furthermore, a fence material layer is also included on the upper part of the plurality of LED units 102, and the fence material layer can be a fence structure 109 having a plurality of grid holes, and the fence structure 109 having a plurality of grid holes includes a plurality of grid holes and a fence structure 109. The plurality of grid holes can be arranged in a regular or irregular manner. The number of grid holes can be set in a one-to-one correspondence with the plurality of LED units 102. The plurality of grid holes can be respectively arranged around the plurality of LED countertops, so that a recessed area is formed between the LED countertops and the corresponding grid holes, and the recessed area can be bowl-shaped.

[0049] In some embodiments, in order to improve the uniformity of the light emission of the LED unit 102, the LED unit 102 may be disposed at the center of the grid hole so that the light emitted by the LED unit can pass through the grid hole uniformly. It should be noted that the present application embodiment does not specifically limit the material of the fence structure 109 having a plurality of grid holes. The material of the fence structure 109 having a plurality of grid holes may include, for example, organic resin, organic black matrix photoresist, color filter photoresist, and polyimide.

[0050] Furthermore, the lens unit 111 is disposed above the LED unit 102 in the recessed area, wherein the lens unit 111 can be made of a transparent material (referred to as Lens material) and prepared into a lens shape. The lens unit 111 having a lens shape can be used to fully transmit the first color light emitted by the LED unit 102, thereby optimizing the light path and increasing the light gathering effect.

[0051] Further, the wavelength conversion layer is arranged above the lens unit 111. The wavelength conversion layer may include a plurality of wavelength conversion units, such as 113 and 114, and the plurality of wavelength conversion units may be filled in the plurality of recessed areas respectively. The wavelength conversion unit may fill at least part of the grid holes, or may fill all the grid holes. The wavelength conversion unit may absorb and convert the light emitted by the LED unit 102.

[0052] In some embodiments, the top surface of the wavelength conversion layer can be flush with the top surface of the fence structure 109. The flush structure can not only effectively prevent light crosstalk between adjacent LED units 102, but also ensure the flatness and stability of the Micro-LED micro-display chip structure, which is convenient for subsequent production processes. In addition, since the wavelength conversion units 113 and 114 of the wavelength conversion layer are filled in the grid holes, the fence structure 109 can support the wavelength conversion units 113 and 114. At the same time, the side surfaces of the wavelength conversion units 113 and 114 are partially wrapped by the fence structure 109, and the contact area is increased, which can increase adhesion and improve yield.

[0053] The Micro-LED micro display chip provided in the above embodiment includes a driving panel, a plurality of LED units, a grid structure, a lens unit and a wavelength conversion layer. The Micro-LED micro display chip can fully transmit the light emitted by the LED unit by setting a lens unit between the LED unit and the wavelength conversion layer, thereby optimizing the light path and increasing the light gathering effect, thereby improving the absorbance and conversion light efficiency of the wavelength conversion layer, and ensuring the purity of the light emitted from the pixel area, thereby improving the screen color gamut and color purity of the Micro-LED display.

[0054] In one embodiment, the Micro-LED micro display chip further includes a fill-in unit, which is disposed between the lens unit and the wavelength conversion unit, and a surface of the fill-in unit in contact with the wavelength conversion unit is a plane. In this embodiment, the lens unit is made of a first transparent material, and the fill-in unit is made of a second transparent material, wherein the refractive index of the first transparent material is higher than the refractive index of the second transparent material.

[0055] In the above embodiment, the filling unit 112 is located above the lens unit 111. Figure 1 When preparing the lens unit 111, the Lens material (i.e., the first transparent material) can be filled into the recessed area formed by the grid structure 109 around the LED table by photolithography technology, and then the Lens material can be shaped into a hemispherical lens morphology by a reflow process. This design can effectively optimize the light path and enhance the light gathering effect, thereby improving the overall brightness. Furthermore, the filling unit 112 can be set above the lens unit 111, and its function is to flatten the surface of the hemispherical lens morphology to form a continuous plane to ensure the continuity of the light path and the uniformity of the display effect.

[0056] In the above embodiment, the lens unit 111 can be made of a first transparent material (Lens material for short), which has a relatively high refractive index, such as high refractive index inorganic materials TiO2, Al2O3, HfO2, etc., or resin materials with a refractive index higher than 1.7, etc. The filling unit 112 can be made of a second transparent material, whose refractive index is lower than that of the first transparent material, such as low refractive index inorganic materials such as SiO2, SiN, MgF2, or organic resin materials with a refractive index lower than 1.5, etc.

[0057] In the above embodiments, by arranging lens units and filling units with different refractive indices between below the wavelength conversion layer and above the LED unit, a distributed Bragg reflector (DBR) or a high refractive index reflector (HBR) structure can be formed by the lens units and the filling units.

[0058] This embodiment arranges lens units and filling units with different refractive indices below the wavelength conversion layer, and can utilize the gradual change characteristics of the lens units and filling units from high refractive index to low refractive index, and select a variety of materials with different refractive indices, so as to effectively reduce the interface light loss between the LED light-emitting surface and the wavelength conversion layer. In this design, the first color light emitted by the bottom LED unit can be fully transmitted. At the same time, the converted light emitted downward by the wavelength conversion layer will be reflected back to the upper surface, which greatly improves the overall light conversion efficiency of the film layer, thereby obtaining a brighter LED micro-display chip. In addition, through the above design, the first color light that the wavelength conversion layer fails to absorb will be reflected back to the wavelength conversion layer for absorption and conversion again. For color quantum dots with weaker absorption capacity, this secondary absorption and conversion mechanism significantly improves its light conversion effect, thereby enhancing the color purity and overall performance of the display chip.

[0059] The above-mentioned lens unit and fill-in unit can adjust and optimize the light path distribution of the LED light source, greatly enhance the light gathering effect, so that more light energy is concentrated in the expected display area, thereby improving the overall display brightness and contrast. In addition, the fill-in unit can eliminate the visual obstacles caused by the curved surface of the lens and ensure that the light can continue to propagate forward smoothly after passing through the lens, thereby achieving the ideal display effect, improving the consistency of the display picture, and improving the optical performance of the Micro-LED micro-display chip.

[0060] In one embodiment, the wavelength conversion layer includes at least a first wavelength conversion unit and a second wavelength conversion unit, wherein the first wavelength conversion unit is disposed above a portion of the LED units, and the second wavelength conversion unit is disposed above another portion of the LED units. In this embodiment, the LED units can emit a first color light, the first wavelength conversion unit can convert the first color light into a second color light, and the second wavelength conversion unit can convert the first color light into a third color light.

[0061] In the above embodiment, referring to Figure 2 , the wavelength conversion layer is composed of at least two different wavelength conversion units, namely the first wavelength conversion unit 113 and the second wavelength conversion unit 114. Among them, the LED unit 102 can emit a first color light, and the first wavelength conversion unit 113 can receive the first color light emitted by the LED unit 102 and convert it into a second color light different from the first color light. The second wavelength conversion unit 114 can receive the first color light and convert it into a third color light different from the first color light and the second color light. Through this design, the Micro-LED micro display chip can produce three different colors of light at the same time, thereby achieving richer color performance.

[0062] The above-mentioned embodiment can significantly improve the color reproduction capability and visual experience of the Micro-LED micro display chip by setting at least two different wavelength conversion units, especially in application scenarios requiring a wide color gamut and high color accuracy, such as high-end monitors or professional-grade displays.

[0063] In one embodiment, the above-mentioned Micro-LED micro display chip also includes a transmissive reflective layer, wherein the transmissive reflective layer is arranged above the first wavelength conversion unit, the second wavelength conversion unit and the grid structure, and is used to reflect the first color light and transmit other color lights.

[0064] In the above embodiment, referring to Figure 2 , the transmissive reflective layer 116 is arranged above the wavelength conversion layer. Specifically, the transmissive reflective layer 116 can be arranged above the first wavelength conversion unit 113, the second wavelength conversion unit 114 and the grid structure 109. Among them, the transmissive reflective layer 116 can be used to reflect the first color light that has passed through the wavelength conversion layer but has not been fully absorbed, and transmit other color lights, including the second color light and the third color light. Among them, the first color light can specifically refer to blue light. By providing the transmissive reflective layer 116, the first color light can be absorbed and converted multiple times inside the wavelength conversion layer until the first color light is absorbed and converted into the desired color light to the maximum extent, thereby significantly improving the light energy utilization efficiency and color purity.

[0065] In one embodiment, the transmissive reflective layer can be made of a distributed Bragg reflector or a high refractive index reflector, wherein the distributed Bragg reflector is composed of two materials with different refractive indices alternately, and the high refractive index reflector is composed of a plurality of materials with different refractive indices and thicknesses alternately fitted by simulation software.

[0066] In the above embodiments, a distributed Bragg reflector (DBR) or a high refractive index reflector (HBR) can be used to prepare the transmissive reflective layer. The distributed Bragg reflector (DBR) is based on the Bragg scattering principle and is prepared by alternating two materials with different refractive indices. The thickness of each layer is precisely set to 1 / 4n wavelength, where n refers to the refractive index of the material of the layer. The reflection performance of DBR is mainly subject to factors such as the number of alternating layers, the difference in refractive index between layers, and the layer boundary conditions. It can achieve precise reflection for specific wavelengths and allow other wavelengths to pass through.

[0067] Furthermore, compared to the distributed Bragg reflector (DBR), the high refractive index reflector (HBR) can adopt a more complex combination of multiple materials and multiple thicknesses, and can be simulated and optimized through simulation software, and different refractive index materials are selected for irregular alternating superposition. Among them, HBR can achieve higher reflection of the corresponding wavelength while having higher transmission of other wavelengths. In addition, in order to achieve the ideal high reflectivity, the HBR structure usually requires at least five pairs of alternating film layers. Among them, alternating film layers refer to a group of film layers composed of multiple different materials alternating.

[0068] In the above embodiments, the DBR material can be prepared by alternating two materials such as TiO2, SiO2, SiNx, HfO2, MgF2, ZrO2, PMMA, etc. The HBR material can be prepared by alternating two or more materials such as TiO2, SiO2, SiNx, HfO2, MgF2, ZrO2, PMMA, etc. It should be understood that this embodiment does not specifically limit the preparation materials of DBR and HBR.

[0069] This embodiment uses a distributed Bragg reflector (DBR) or a high refractive index reflector (HBR) to prepare a transmissive reflective layer, which can take into account both preparation cost and performance optimization. On the one hand, the DBR structure is easy to manufacture and cost-controlled, and is suitable for large-scale production environments; on the other hand, the HBR structure has good flexibility and efficiency, and is suitable for use in quantum dot structure designs that require extremely high light conversion efficiency, to ensure that the color purity and brightness performance of the display device are maximized. Through the above dual design, a balance between optical performance and cost can be achieved in different application scenarios.

[0070] In one embodiment, the wavelength conversion layer further includes a third wavelength conversion unit, which is disposed above another portion of the LED units, and the third wavelength conversion unit can convert the first color light into a fourth color light. Alternatively, the wavelength conversion layer further includes a light-transmitting filling unit, which is disposed above another portion of the LED units, and the first color light can be transmitted through the light-transmitting filling unit.

[0071] In the above embodiment, the wavelength conversion layer may further include a third wavelength conversion unit capable of converting the first color light into a fourth color light, so that the Micro-LED micro display chip can emit the second color light, the third color light and the fourth color light respectively through the first wavelength conversion unit, the second wavelength conversion unit and the third wavelength conversion unit, thereby achieving full-color display. Figure 2The wavelength conversion layer may also include a light-transmitting filling unit 115 that allows the first color light to pass through, so that the Micro-LED micro display chip emits the second color light, the third color light and the first color light respectively through the first wavelength conversion unit 113, the second wavelength conversion unit 114 and the light-transmitting filling unit 115, thereby realizing another full-color display.

[0072] This embodiment enables the Micro-LED micro display chip to emit light sources with different color combinations by setting different types of wavelength conversion units, thereby improving the color gamut of the Micro-LED micro display chip.

[0073] In the above embodiment, the transmissive reflective layer can also be arranged above the third wavelength conversion unit, and at the same time, the transmissive reflective layer is not arranged above the light-transmitting filling unit. The transmissive reflective layer can be used to reflect the first color light that has passed through the wavelength conversion layer but has not been fully absorbed. By arranging the transmissive reflective layer, the first color light can be absorbed and converted multiple times inside the wavelength conversion layer until the first color light is absorbed and converted to the desired color light to the maximum extent, thereby significantly improving the light energy utilization efficiency and color purity. At the same time, the transmissive reflective layer is not arranged above the light-transmitting filling unit so that the first color light emitted by the LED unit can continue to be transmitted through the light-transmitting filling unit, thereby ensuring the color purity of the first color light.

[0074] The process flow of the structure is described below by taking the case where the first color light is blue light as an example.

[0075] In this embodiment, the specific process flow for realizing the above functions is as follows: Figure 2 First, a layer of distributed Bragg reflector (DBR) material or high refractive index reflector (HBR) material is deposited on top of the wavelength conversion layer. The material is composed of thin films of different refractive indices stacked alternately, so that the reflective layer has high transmittance to other color lights except the first color light, and exhibits good reflection characteristics to the first color light. In this embodiment, the DBR structure or the HBR structure can be photolithographically prepared and masked, that is, the area corresponding to the first color light can be patterned, that is, the patterning can be performed above the light-transmitting filling unit 115 to ensure that the reflective layer does not hinder the effective transmission of the first color light, so as to obtain a transmissive reflective layer 116 that can cover the light-emitting surface of other color lights.

[0076] In this embodiment, a transmissive reflective layer 116 having a distributed Bragg reflector (DBR) structure or a high refractive index reflector (HBR) structure is prepared above the wavelength conversion layer. The first color light that is not absorbed by the first wavelength conversion unit 113 and the second wavelength conversion unit 114 can be effectively blocked through the selective filtering effect of the transmissive reflective layer 116, thereby improving the light absorption efficiency of the wavelength conversion layer for the first color light. This design helps to improve the spectral purity in the pixel area, ensure the purity of the second color light and the third color light, and thus enhance the color gamut coverage of the overall display screen. In addition, the unabsorbed one-color light reflected back has the opportunity to pass through the wavelength conversion layer again and induce a secondary absorption conversion process. This is particularly important for quantum dots of other color lights that absorb the first color light less, because it can increase the probability that the quantum dots of other color lights capture and convert the first color light, further improving the light purity of other color lights, thereby improving the color expression and brightness uniformity of the entire display system.

[0077] In one embodiment, the Micro-LED micro display chip further includes a filter layer, which includes a plurality of filter units. The plurality of filter units may be disposed above the transmissive reflective layer and above the wavelength conversion unit. Alternatively, some of the filter units may be disposed above the transmissive reflective layer and above the wavelength conversion unit, and other filter units may be disposed above the light-transmitting filling unit.

[0078] In this embodiment, refer to Figure 2 The filter layer can achieve accurate screening of light and optimize the display effect. The filter layer can include multiple different types of filter units, such as a first filter unit 117, a second filter unit 118, and a third filter unit 119. The multiple types of filter units can be respectively arranged above the transmissive reflective layer 116, and located above the first wavelength conversion unit 113 and the second wavelength conversion unit 114, or directly arranged above the light-transmitting filling unit 115, and are used to filter light of different colors respectively, and only transmit light of corresponding colors, so that the Micro-LED micro display chip achieves the effect of filtering.

[0079] For example, refer to Figure 2, the first filter unit 117 can be arranged above the transmissive reflective layer 116 and above the first wavelength conversion unit 113. Among them, the first wavelength conversion unit 113 can convert the first color light emitted by the LED unit 102 into the second color light. Therefore, the first filter unit 117 only allows the second color light to pass smoothly, and filters out other color lights except the second color light. Similarly, the second filter unit 118 can be arranged above the transmissive reflective layer 116 and above the second wavelength conversion unit 114, and is used to allow only the third color light to pass smoothly, and filter out other color lights except the third color light. The third filter unit 119 can be arranged above the light-transmitting filling unit 115 of the wavelength conversion layer, and is used to allow only the first color light to pass smoothly, and filter out other color lights except the first color light, so that the Micro-LED micro display chip achieves a filtering effect.

[0080] This embodiment not only strengthens the color separation effect but also improves the color reproduction capability and display quality of the Micro-LED micro display chip by preparing a filter layer on the Micro-LED micro display chip.

[0081] In one embodiment, the Micro-LED micro display chip further includes an etching barrier layer, and the etching barrier layer at least covers the LED mesas of the LED unit.

[0082] In this embodiment, refer to Figure 2 The etching stopper 108 can be disposed between the LED unit 102 and the grid structure 109, and at least covers the LED table of the LED unit 102. Specifically, the etching stopper 108 can cover the driving panel 101, the light emitting surface and the side surface of the LED unit 102. The etching stopper 108 can effectively prevent light from crosstalking between different pixel units, thereby improving the clarity and color accuracy of the displayed image quality.

[0083] Specifically, the preparation process of the etching stop layer may include the following steps: Figure 2 First, mask technology can be used for patterning. Then, the overall etching technology is used to etch the selected light-transmitting material such as silicon dioxide (SiO2). Among them, the light-transmitting material can be a material with excellent light transmittance and good etching characteristics. Through etching, an etching barrier layer 108 with a suitable thickness and accurate boundaries can be created on the light-emitting surface and side of the driving panel 101 and the LED unit 102, thereby ensuring that the light emitted by the LED unit 102 is confined to the respective pixel area as much as possible, thereby reducing unnecessary light leakage and cross interference, thereby improving the display performance of the Micro-LED micro display chip.

[0084] In one embodiment, the Micro-LED micro display chip may further include a reflective layer, and the reflective layer at least covers the side walls of each grid hole of the grid structure.

[0085] In this embodiment, refer to Figure 2 By providing the reflective layer 110, the pixel brightness can be enhanced and the light loss can be reduced. The reflective layer 110 can be arranged on the side walls of each grid hole of the entire grid structure 109 to maximize the reflection of the light emitted by the LED unit 102 and possibly escaping to the non-display area, thereby improving the overall brightness and contrast of the display effect.

[0086] Specifically, the process of preparing the reflective layer may include the following steps: Figure 2 First, a grid structure 109 is prepared in a specific area of ​​the Micro-LED display chip by photolithography technology. In this process, the entire substrate can be coated with photoresist, and then exposed and developed to create a mask pattern consistent with the desired grid shape. Then, the entire surface of the grid structure formed by photolithography is metallized. In this step, a metal material with good reflective properties, such as aluminum (Al), can be used to effectively reflect the light generated by the LED unit 102. Finally, part of the metal layer is selectively removed by dry etching technology. Specifically, through chemical reaction or physical impact, only the metal layer on the side wall of the grid hole can be retained, and the metal in other positions can be removed, thereby forming a metal reflective layer 110 that is bonded around the grid hole.

[0087] This embodiment prepares a reflective layer on the side walls of each grid hole of the grid structure, so that the LED light that would otherwise be lost can be guided back to the display area, thereby effectively improving the optical efficiency and display quality of the Micro-LED micro display chip.

[0088] In one embodiment, the wavelength conversion layer contains wavelength conversion particles, wherein the wavelength conversion particles may be phosphors and / or quantum dots.

[0089] In the above embodiment, the material of the wavelength conversion layer may include wavelength conversion particles. In addition, the material of the wavelength conversion layer may also include photoresist. The wavelength conversion particles may be, for example, phosphors and / or quantum dots, etc., and the present application embodiment does not impose specific restrictions on this. For example, the quantum dots may be colloidal quantum dots. The wavelength conversion layer may be obtained by an exposure and development process, and the preparation process is simple and controllable.

[0090] It should be noted that the photoresist in the embodiment of the present application includes but is not limited to Overcoat glue, SU8 (near ultraviolet negative photoresist), benzocyclobutene (BCB), etc., and can also be SiO2, Al2O3, Si3N4, etc. The phosphor can be yttrium aluminum garnet, cerium phosphor, (oxy) nitride phosphor, silicate phosphor and Mn4+ activated fluoride phosphor, etc. The quantum dot can include one or more combinations of CdSe, CdS, CdZnSe, CdZnS, CdZnSeS, ZnSeS, ZnSe, CuInS, CuInSe, InP, InZnP and perovskite quantum dots, etc., and the present application does not make specific restrictions.

[0091] In one embodiment, Figure 3 FIG. 1 is a schematic diagram of a method for preparing a Micro-LED micro display chip according to an embodiment of the present application. Figure 3 As shown, the preparation method of the above-mentioned Micro-LED micro display chip includes the following steps:

[0092] 201. Provide a drive panel.

[0093] 202. A plurality of LED units are formed on a driving panel, wherein the plurality of LED units have a plurality of LED tables corresponding to each other, and each LED unit can be driven individually by the driving panel.

[0094] 203. Form a grid structure with a plurality of grid holes, wherein the plurality of grid holes are respectively arranged around a plurality of LED countertops, and a recessed area is formed between the LED countertops and the corresponding grid holes.

[0095] 204. Form a lens unit above the LED unit in the recessed area.

[0096] 205. Form a wavelength conversion layer above the lens unit, wherein the wavelength conversion layer includes a plurality of wavelength conversion units.

[0097] The method for preparing the Micro-LED micro display chip provided in the above embodiment can sequentially prepare multiple LED units, grid structures, lens units and wavelength conversion layers on the driving panel. By setting a lens unit between the LED unit and the wavelength conversion layer, the light emitted by the LED unit can be fully transmitted, thereby optimizing the light path and increasing the light gathering effect, thereby improving the absorbance and conversion light efficiency of the wavelength conversion layer, ensuring the purity of the light emitted from the pixel area, and improving the screen color gamut and color purity of the Micro-LED display.

[0098] In one embodiment, step 204 can be implemented by the following method: filling the LED unit in the recessed area with a first transparent material, and reflowing the first transparent material to form a lens morphology of the first transparent material to obtain a lens unit.

[0099] In one embodiment, the method for preparing the above-mentioned Micro-LED micro display chip also includes the following steps: filling a second transparent material above the lens unit so that the second transparent material fills the lens unit into a plane to obtain a flattened unit; wherein the refractive index of the first transparent material used to prepare the lens unit is higher than the refractive index of the second transparent material used to prepare the flattened unit.

[0100] In one embodiment, step 205 can be implemented by the following method: forming a first wavelength conversion unit above some LED units, and forming a second wavelength conversion unit above other LED units; the LED units are capable of emitting a first color light; the first wavelength conversion unit converts the first color light into a second color light; the second wavelength conversion unit converts the first color light into a third color light. The above-mentioned method for preparing the Micro-LED micro display chip also includes step 206: forming a transmissive reflective layer above the first wavelength conversion unit, the second wavelength conversion unit and the grid structure, wherein the transmissive reflective layer is used to reflect the first color light and transmit other color lights.

[0101] In one embodiment, step 205 may further include the following steps: forming a third wavelength conversion unit above another portion of the LED unit, the third wavelength conversion unit converting the first color light into a fourth color light; or, forming a light-transmitting filling unit above another portion of the LED unit, the first color light being transmitted through the light-transmitting filling unit.

[0102] In one embodiment, step 206 can be implemented by the following method: coating the top surface of the grid structure and the top surface of the wavelength conversion layer with a reflector material; patterning the reflector material above the light-transmitting filling unit, and exposing and developing the reflector material to obtain a transmissive reflective layer.

[0103] In one embodiment, the preparation method of the above-mentioned Micro-LED micro display chip also includes the following steps: forming a plurality of filter units above the transmission reflective layer and above the wavelength conversion unit to obtain a filter layer; or forming a plurality of filter units above the transmission reflective layer and above the wavelength conversion unit, and forming a plurality of filter units above the light-transmitting filling unit to obtain a filter layer.

[0104] In one embodiment, after forming a plurality of LED units on the driving panel, the method for preparing the above-mentioned Micro-LED micro display chip may further include the following steps: covering the etch barrier material at least on the LED table of the LED unit to form an etch barrier layer.

[0105] In one embodiment, after forming a grid structure having a plurality of grid holes, the method for preparing the above-mentioned Micro-LED micro display chip may further include the following steps: evaporating metal on the grid structure, the driving panel, the light emitting surface and the side surfaces of the LED unit, and removing the metal on the top surface of the grid structure, the driving panel, the light emitting surface and the side surfaces of the LED unit by dry etching, retaining the metal on the side walls of each grid hole of the grid structure, and obtaining a reflective layer.

[0106] In one embodiment, a method for forming a wavelength conversion layer on a grid structure may include the following steps: mixing wavelength conversion particles and photoresist in a preset ratio to prepare a quantum dot film layer, and spin coating the quantum dots on top of the LED unit, or spin coating on top of the reflective layer on the upper surface of the LED unit to obtain a wavelength conversion layer, wherein the wavelength conversion particles are phosphors and / or quantum dots.

[0107] In one embodiment, step 202 may be implemented by the following method: forming an LED epitaxial layer on a substrate; bonding the LED epitaxial layer to a driving panel; and etching the LED epitaxial layer to form a plurality of LED units on the driving panel.

[0108] For the specific implementation process of each embodiment of the preparation method of the above-mentioned Micro-LED micro display chip, reference can be made to the embodiment of the Micro-LED micro display chip, and no further description is given here. It can be understood that the preparation process, specific structure and technical effect of the Micro-LED micro display chip prepared by the preparation method of the Micro-LED micro display chip of each embodiment above correspond to those of the Micro-LED micro display chip in the embodiments of the above-mentioned Micro-LED micro display chip.

[0109] In one embodiment, in order to better understand the preparation method of the Micro-LED micro display chip in the embodiment of the present application, the following is combined with Figures 4 to 16 , the preparation method of Micro-LED micro display chip is introduced in detail. Figures 4 to 16 The cross-sectional structure diagram of the Micro-LED micro display chip at different stages in the preparation process is exemplarily shown. It should be understood that for the contents not described in detail in this section, reference can be made to the description of some embodiments of the Micro LED micro display chip.

[0110] In some embodiments, reference Figure 4 First, a driving panel 301 is provided. The driving panel 301 may include a circuit layer composed of complementary metal oxide semiconductor CMOS devices or TFT devices. These CMOS devices or TFT devices may form a driving circuit in the driving panel 301. At the same time, the driving panel 301 may also include a plurality of contacts connected to the driving circuit, and the plurality of LED units 302 arranged on the driving panel 301 may be electrically connected to the plurality of contacts.

[0111] In some embodiments, reference Figure 4 The plurality of contacts include a first electrode contact 303 and a second electrode contact 304. The first electrode contact 303 can be electrically connected to each LED unit 302, and the second electrode contact 304 can be electrically connected to the plurality of LED units 302 to drive any one of the plurality of LED units 302 to emit light.

[0112] In some embodiments, reference Figure 4 The MESA pattern can be designed according to the patterned mask, and the LED epitaxial layer can be etched to form a plurality of LED units 302 with LED terraces, and the LED units 302 are functional step structures. It should be understood that etching includes dry or wet methods.

[0113] In some embodiments, reference Figure 4 , a plurality of first electrode layers 305 can be formed by etching the bonding layer, and the plurality of first electrode layers 305 are arranged one by one with the plurality of LED units 302. And adjacent LED units 302 cannot be electrically connected through the first electrode layer 305. The first electrode layer 305 is electrically connected to the first electrode contact 303, and the driving circuit in the driving panel 301 can apply an anode voltage to the LED unit 302 separately through the first electrode contact 303, and provide a separate driving signal, so as to achieve the purpose of controlling each LED unit 302 to emit light separately.

[0114] In some embodiments, reference Figure 4 , a passivation layer 306 may be deposited on the sidewall surface of the LED unit 302. The material of the passivation layer 306 may include an inorganic material or an organic material.

[0115] In some embodiments, reference Figure 4, a second electrode layer 307 may be provided between the LED units 302, and the second electrode layer 307 may be located on the upper portion of the driving panel 301 and outside the passivation layer 306. The second electrode layer 307 may connect the first semiconductor layers of the plurality of LED units 302, and the second electrode layer 307 is a common cathode electrode layer of the Micro LED micro display chip, and the second electrode contact 304 may be connected to the second electrode layer 307, so as to form a conductive loop with the first electrode contact 303 to drive the LED units 302 to emit light.

[0116] In some embodiments, reference Figure 5 , an etching stop layer 308 can be formed on the side wall and the top surface of the LED table. The etching stop layer 308 covers the multiple LED units 302 and the second electrode layer 307. Among them, the etching stop layer 308 is a continuous film structure, which can prevent etching damage to the LED table or the second electrode layer 307. In addition, the etching stop layer 308 can transmit the light emitted by the LED unit 302, that is, the etching stop layer 308 has sufficient transparency, and can generally be made of silicon dioxide, silicon nitride, aluminum oxide and the like.

[0117] In some embodiments, reference Figure 6 , a fence material layer can be formed on the upper part of the plurality of LED units 302. The material of the fence material layer may include, for example, organic resin, organic black matrix photoresist, color filter photoresist, and polyimide. Then, the fence material layer is etched to form a fence structure 309 having a plurality of grid holes. The plurality of grid holes can be respectively arranged around the plurality of LED countertops, and a recessed area is formed between the LED countertops and the corresponding grid holes. It should be understood that the plurality of grid holes are arranged in a one-to-one correspondence with the plurality of LED units 302, so that the light emitted by the LED units 302 can be emitted through the grid holes.

[0118] In some embodiments, the fence structure 309 is disposed on the barrier layer 308, and the grid holes of the fence structure 309 can be formed by dry etching, and the grid holes expose the barrier layer 308. Since the barrier layer 308 covers the upper part of the LED table and the upper part of the second electrode layer 307, the LED table and the second electrode layer 307 can be prevented from being damaged during the etching of the grid holes.

[0119] In some embodiments, reference Figure 7 In order to enhance the reflection effect of the light emitted by the LED unit 302 , a reflective material layer may be formed on the plurality of LED tables and the fence structure 309 .

[0120] In some embodiments, reference Figure 8 The reflective material layer on the plurality of LED tables can be removed by etching to form a reflective layer 310 on the sidewalls of the grid holes.

[0121] In some embodiments, the reflective layer 310 may also be formed by dry etching, wherein the so-called dry etching includes but is not limited to ion beam etching IBE and inductively coupled plasma ICP etching. In some embodiments, the above-mentioned dry etching method may be used to etch the entire surface of the reflective layer 310 after deposition, so that the reflective layer on the upper part of the LED unit 302 is etched cleanly, and at the same time, the reflective layer 310 will have a plasma re-deposition effect during the etching process, resulting in the thickening of the side wall reflective layer 310, enhancing the reflective effect, and strengthening the stability of the fence structure 309 and the overall structure. In this way, the preparation process can be simplified, and no additional photolithography steps are required to make the etching mask.

[0122] In some embodiments, reference Fig. 9 , the first transparent material may be filled in the concave area formed by the fence structure 309 and the LED table, and further, referring to Fig.10 After the first transparent material is solidified, the first transparent material may be subjected to a reflow process to form a lens unit 311 having a lens morphology.

[0123] In some embodiments, reference Fig.11 The second transparent material may be filled above the lens unit 311 to form a flattening unit 312, wherein the flattening unit 312 may flatten the lens morphology into a plane. The refractive index of the first transparent material is higher than the refractive index of the second transparent material.

[0124] In some embodiments, reference Fig.12 A wavelength conversion layer can be formed on the filling unit 312, and the wavelength conversion layer includes a plurality of wavelength conversion units 313. The plurality of wavelength conversion units 313 are respectively filled in a plurality of recessed areas, and the top surface of the wavelength conversion unit 313 is flush with the top surface of the grid structure 309.

[0125] In some embodiments, reference Fig.12 , a first wavelength conversion layer is formed on the filling unit 312, for example, the wavelength conversion layer can be formed by spin coating and drying. The material of the wavelength conversion layer includes wavelength conversion particles, and the wavelength conversion particles can be, for example, phosphors and / or quantum dots. Among them, the wavelength conversion layer can include a first wavelength conversion unit 313, a second wavelength conversion unit 314 and a light-transmitting filling unit 315. In this embodiment, the LED unit 302 can emit a first color light, the first wavelength conversion unit 313 can convert the first color light into a second color light, the second wavelength conversion unit 314 can convert the first color light into a third color light, and the light-transmitting filling unit 315 can transmit the first color light.

[0126] In some embodiments, reference Fig.13, the top surface of the grid structure 309 and the top surface of the wavelength conversion layer may be coated with a reflector material. Fig.14 , the reflector material corresponding to the light exiting surface of the first color light can be patterned, that is, the reflector material above the light-transmitting filling unit 315 can be patterned. Fig.15 The reflector material can be exposed and developed to obtain a transmissive reflective layer 316 above the wavelength conversion layer.

[0127] In some embodiments, the transmissive reflective layer is made of a distributed Bragg reflector and / or a high refractive index reflector. The distributed Bragg reflector is composed of two materials with different refractive indices alternately, and the high refractive index reflector is composed of two or more materials with different refractive indices alternately.

[0128] In some embodiments, the high refractive index reflector is composed of a plurality of materials with different refractive indices and thicknesses alternately fitted by simulation software, wherein the number of groups of alternating film layers composed of materials with different refractive indices alternately is greater than five.

[0129] In some embodiments, reference Fig.16 , a filter layer may be formed on the transmissive reflective layer 316 .

[0130] In some embodiments, reference Fig.16 The filter layer includes a first filter unit 317, a second filter unit 318 and a third filter unit 319. The first filter unit 317 is arranged above the transmissive reflective layer 316 and above the first wavelength conversion unit 313, the second filter unit 318 is arranged above the transmissive reflective layer 316 and above the second wavelength conversion unit 314, and the third filter unit 319 is arranged above the light-transmitting filling unit 315.

[0131] In some embodiments, in order to verify the actual effect of disposing a lens unit and a fill-up unit below the wavelength conversion layer and disposing a transmissive reflective layer above the wavelength conversion layer, the following experimental cases are designed:

[0132] Experimental case 1: an experimental case in which the lens unit, the filling unit and the transmissive reflective layer are not provided.

[0133] Preparation method: CdSe / ZnS and transparent negative resist are mixed in an appropriate volume ratio to prepare a QDPR film layer (wavelength conversion layer), and then prepared on the surface of the LED by spin coating.

[0134] Experimental case 2: An experimental case in which a transmissive reflective layer is provided above the wavelength conversion layer.

[0135] Preparation method: CdSe / ZnS and transparent negative resist are mixed in an appropriate volume ratio to prepare a QDPR film layer, and then prepared on the LED surface by spin coating. Then SiO2, TiO2 stacked DBR or SiO2, TiO2; or MgF2 stacked HBR are prepared on the QDPR surface by evaporating SiO2, TiO2 through an optical coating machine.

[0136] Experimental case 3: an experimental case in which a lens unit and a filling unit are arranged below the wavelength conversion layer.

[0137] Preparation method: SiO2, TiO2 stacked DBR or SiO2, TiO2; or MgF2 stacked HBR are prepared on the surface of LED by evaporation through an optical coating machine, and then CdSe / ZnS and transparent negative resist are mixed in an appropriate volume ratio to prepare a QDPR film layer, and then prepared on the HBR surface by spin coating.

[0138] Experimental case 4: an experimental case in which a lens unit and a fill-up unit are arranged below the wavelength conversion layer, and a transmissive reflective layer is arranged above the wavelength conversion layer.

[0139] Preparation method: SiO2, TiO2 laminated DBR or SiO2, TiO2; or MgF2 laminated HBR is prepared on the surface of LED by evaporating SiO2, TiO2 through an optical coating machine, and then CdSe / ZnS and transparent negative resist are mixed in an appropriate volume ratio to prepare a QDPR film layer, which is prepared on the surface of HBR by spin coating, and then SiO2, TiO2 laminated DBR or SiO2, TiO2; or MgF2 laminated HBR is prepared on the surface of QDPR by evaporating SiO2, TiO2 through an optical coating machine.

[0140] After testing the above experimental cases, the test results shown in Tables 1 and 2 can be obtained. Among them, in Tables 1 and 2, by changing the materials and preparation methods of the lens unit and the filling unit, the reflective structure composed of the lens unit and the filling unit can be equated to a distributed Bragg reflector (DBR) structure or a high refractive index reflector (HBR) structure. Based on this, it can be seen from the above test results that by setting the lens unit and the filling unit below the wavelength conversion layer and setting the transmissive reflective layer above the wavelength conversion layer, the light output efficiency and color purity of the wavelength conversion layer can be greatly affected, thereby improving the absorbance and conversion efficiency of the wavelength conversion layer, and then ensuring the purity of the light output in the pixel area, and improving the screen color gamut and color purity of the Micro-LED display.

[0141] Table 1

[0142]

[0143]

[0144] It can be seen from the data in Table 1 that by arranging a distributed Bragg reflector (DBR) or a high refractive index reflector (HBR) composed of a lens unit and a filling unit below the wavelength conversion layer, and arranging a transmissive reflective layer with a distributed Bragg reflector (DBR) structure or a high refractive index reflector (HBR) structure above the wavelength conversion layer, the light output brightness of the wavelength conversion layer can be significantly improved.

[0145] Table 2

[0146]

[0147] It can be seen from the data in Table 2 that by arranging a distributed Bragg reflector (DBR) or a high refractive index reflector (HBR) composed of a lens unit and a filling unit below the wavelength conversion layer, and arranging a transmissive reflective layer with a distributed Bragg reflector (DBR) structure or a high refractive index reflector (HBR) structure above the wavelength conversion layer, the absorbance of the wavelength conversion layer can be significantly improved, thereby improving the color purity of the display.

[0148] Further, see Fig.17 By preparing a reflective layer with a distributed Bragg reflector (DBR) structure on the upper surface of the wavelength conversion layer, the blue light that is not absorbed by the red and green wavelength conversion layers can be effectively blocked through the selective filtering effect of the reflective layer, thereby improving the wavelength conversion layer's absorption efficiency for blue light. This design helps to improve the spectral purity within the pixel area, ensuring that the red and green pixels only emit light of the corresponding colors, thereby enhancing the color gamut coverage of the overall display screen. In addition, the unabsorbed blue light reflected back has the opportunity to pass through the wavelength conversion layer again and induce a secondary absorption conversion process. This is especially important for green quantum dots that absorb blue light weakly, because it can increase the probability of green quantum dots capturing and converting blue light, further improving the luminous efficiency of green sub-pixels, thereby improving the color expression and brightness uniformity of the entire display system.

[0149] Further, see Fig.18By setting an HBR structure consisting of a lens unit and a filling unit under the wavelength conversion layer, the gradual change characteristics from high refractive index to low refractive index in the HBR structure can be utilized, and a variety of materials with different refractive indices can be selected, so as to effectively reduce the interface light loss between the LED light-emitting surface and the wavelength conversion layer. In particular, in the HBR design, the blue light emitted by the bottom LED can be fully transmitted. At the same time, the converted light emitted downward by the wavelength conversion layer will be reflected back to the upper surface, which greatly improves the overall light conversion efficiency of the film layer, thereby obtaining a brighter color LED chip. In addition, through the HBR design, the blue light that the wavelength conversion layer fails to absorb will be reflected back to the wavelength conversion layer for absorption and conversion again. For green quantum dots with weaker absorption capacity, this secondary absorption and conversion mechanism significantly improves its light conversion effect, thereby enhancing the color purity and overall performance of the display chip.

[0150] It should be noted that the embodiments of the method for preparing the Micro-LED micro display chip in this application only describe the production process or steps. The device structure, shape, and materials not described can refer to the above-mentioned embodiments of the Micro LED micro display chip and will not be repeated here.

[0151] As another optional implementation of the disclosure of the present application, an embodiment of the present application further provides a display device, the display device includes a Micro-LED micro display chip, and the Micro-LED micro display chip can be a Micro-LED micro display chip provided in any of the above embodiments. The display device can be, for example, a component or device including a Micro-LED micro display chip, such as a Micro-LED micro display chip device including an encapsulation layer.

[0152] As another optional implementation of the disclosure of the present application, an embodiment of the present application further provides an electronic device. The electronic device may include, for example, a Micro-LED micro display chip or a display device. The Micro-LED micro display chip may be a Micro LED micro display chip provided in any of the above embodiments.

[0153] The electronic devices in the embodiments of the present application include, but are not limited to: display devices such as augmented reality (AR) display devices, virtual reality (VR) display devices, near-eye displays (NED) and heads-up displays (HUD) devices.

[0154] The above-mentioned embodiments only express several implementation methods of the present invention, and the descriptions thereof are relatively specific and detailed, but they cannot be understood as limiting the scope of the invention patent. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, and these all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A Micro-LED micro display chip, characterized in that: The Micro-LED micro display chip includes: Driver panel; A plurality of LED units are arranged on the driving panel, the plurality of LED units have a plurality of LED tables corresponding to each other, and each of the LED units can be driven individually by the driving panel; A grid structure having a plurality of grid holes, wherein the plurality of grid holes are respectively arranged around the plurality of LED countertops, and a recessed area is formed between the LED countertops and the corresponding grid holes; A lens unit is disposed in the recessed area and located above the LED unit; The wavelength conversion layer includes a plurality of wavelength conversion units, and the plurality of wavelength conversion units are arranged above the lens unit.

2. The Micro-LED micro display chip according to claim 1, characterized in that: The Micro-LED micro display chip further includes: A filling unit is provided between the lens unit and the wavelength conversion unit, wherein a surface of the filling unit in contact with the wavelength conversion unit is a plane; The lens unit is made of a first transparent material, and the filling unit is made of a second transparent material, wherein the refractive index of the first transparent material is higher than the refractive index of the second transparent material.

3. The Micro-LED micro display chip according to claim 1 or 2, characterized in that: The wavelength conversion layer at least includes a first wavelength conversion unit and a second wavelength conversion unit, the first wavelength conversion unit is arranged above a portion of the LED units, and the second wavelength conversion unit is arranged above another portion of the LED units; The LED unit is capable of emitting light of a first color; The first wavelength conversion unit converts the first color light into a second color light; The second wavelength conversion unit converts the first color light into a third color light.

4. The Micro-LED micro display chip according to claim 3, characterized in that: The Micro-LED micro display chip further includes: The transmissive reflective layer is disposed above the first wavelength conversion unit, the second wavelength conversion unit and the grid structure, and is used for reflecting the first color light and transmitting other color lights.

5. The Micro-LED micro display chip according to claim 4, characterized in that: The transmissive reflective layer is made of a distributed Bragg reflector, which is composed of two materials with different refractive indices alternately; Alternatively, the transmissive reflective layer is made of a high refractive index reflective mirror, and the high refractive index reflective mirror is composed of a plurality of materials with different refractive indices and thicknesses fitted by simulation software.

6. The Micro-LED micro display chip according to claim 4, characterized in that: The wavelength conversion layer further includes a third wavelength conversion unit, and the third wavelength conversion unit is disposed above another portion of the LED unit; The third wavelength conversion unit converts the first color light into a fourth color light; The transmissive reflective layer is also disposed above the third wavelength conversion unit and is used to reflect the first color light and transmit other color lights; or, The wavelength conversion layer further includes a light-transmitting filling unit, which is disposed above another portion of the LED unit, and the first color light is transmitted through the light-transmitting filling unit.

7. The Micro-LED micro display chip according to claim 6, characterized in that: The Micro-LED micro display chip further includes a light filter layer, and the light filter layer includes a plurality of light filter units; The plurality of filter units are disposed above the transmissive reflective layer and above the wavelength conversion unit; Alternatively, part of the filter unit is disposed above the transmissive reflective layer and above the wavelength conversion unit, and another part of the filter unit is disposed above the light-transmitting filling unit.

8. The Micro-LED micro display chip according to claim 1, characterized in that: The Micro-LED micro display chip further includes an etching barrier layer, and the etching barrier layer at least covers the LED table of the LED unit.

9. The Micro-LED micro display chip according to claim 1, characterized in that: The Micro-LED micro display chip further includes a reflective layer, and the reflective layer at least covers the side walls of each grid hole of the grid structure.

10. The Micro-LED micro display chip according to claim 1, characterized in that: The wavelength conversion layer contains wavelength conversion particles, and the wavelength conversion particles are fluorescent powder and / or quantum dots.

11. A method for preparing a Micro-LED micro display chip, characterized in that: The method comprises: Providing a drive panel; A plurality of LED units are formed on the driving panel, wherein the plurality of LED units have a plurality of LED tables corresponding to each other, and each of the LED units can be driven individually by the driving panel; forming a grid structure having a plurality of grid holes, wherein the plurality of grid holes are respectively arranged around the plurality of LED countertops, and a recessed area is formed between the LED countertops and the corresponding grid holes; forming a lens unit above the LED unit in the recessed area; A wavelength conversion layer is formed above the lens unit, wherein the wavelength conversion layer includes a plurality of wavelength conversion units.

12. The method according to claim 11, characterized in that The lens unit is formed above the LED unit in the recessed area, comprising: A first transparent material is filled above the LED unit in the recessed area, and the first transparent material is subjected to a reflow process so that the first transparent material forms a lens shape to obtain a lens unit.

13. The method according to claim 11, characterized in that The method further comprises: Filling a second transparent material above the lens unit so that the second transparent material fills the lens unit into a flat surface to obtain a flattened unit; The refractive index of the first transparent material used to prepare the lens unit is higher than the refractive index of the second transparent material used to prepare the filling unit.

14. The method according to any one of claims 11 to 13, characterized in that The step of forming a wavelength conversion layer above the lens unit comprises: forming a first wavelength conversion unit above a portion of the LED units, and forming a second wavelength conversion unit above another portion of the LED units; The LED unit is capable of emitting light of a first color; The first wavelength conversion unit converts the first color light into a second color light; The second wavelength conversion unit converts the first color light into a third color light; The method further includes: forming a transmissive reflective layer above the first wavelength conversion unit, the second wavelength conversion unit, and the grid structure, wherein the transmissive reflective layer is used to reflect the first color light and transmit other color lights.

15. The method according to claim 14, characterized in that The step of forming a wavelength conversion layer above the lens unit further comprises: forming a third wavelength conversion unit above another portion of the LED unit, wherein the third wavelength conversion unit converts the first color light into a fourth color light; Alternatively, a light-transmitting filling unit is formed above another portion of the LED unit, and the first color light is transmitted through the light-transmitting filling unit.

16. The method according to claim 15, characterized in that The forming of a transmissive reflective layer above the first wavelength conversion unit, the second wavelength conversion unit and the grid structure comprises: Coating a reflector material on the top surface of the grid structure and the top surface of the wavelength conversion layer; The reflector material above the light-transmitting filling unit is patterned, and the reflector material is exposed and developed to obtain the transmissive reflective layer.

17. The method according to claim 15, characterized in that The method further comprises: forming a plurality of filter units above the transmissive reflective layer and above the wavelength conversion unit to obtain a filter layer; Alternatively, a plurality of filter units are formed above the transmissive reflective layer and above the wavelength conversion unit, and a plurality of filter units are formed above the light-transmitting filling unit to obtain a filter layer.

18. The method according to claim 11, characterized in that After forming a plurality of LED units on the driving panel, the method further comprises: The etch stop layer material is covered at least on the LED mesa of the LED unit to form an etch stop layer.

19. The method according to claim 11, characterized in that After forming the grid structure having a plurality of grid holes, the method further comprises: Metal is evaporated on the grid structure, the driving panel, the light emitting surface and the side surfaces of the LED unit, and the metal on the top surface of the grid structure, the driving panel, the light emitting surface and the side surfaces of the LED unit is removed by dry etching, while the metal on the side walls of each grid hole of the grid structure is retained to obtain a reflective layer.

20. The method according to claim 11, characterized in that The plurality of LED units are formed on the driving panel, comprising: forming an LED epitaxial layer on the substrate; Bonding the LED epitaxial layer to the driving panel; The LED epitaxial layer is etched to form a plurality of LED units on the driving panel.

Images