Micro LED micro-display chip and manufacturing method therefor

Abstract

The present disclosure relates to the technical field of display chips. Provided are a Micro LED micro-display chip and a manufacturing method therefor. The micro-display chip comprises a drive substrate, and a light-emitting structure arranged on the drive substrate. The light-emitting structure comprises: a plurality of LED units arranged spaced apart from each other on the drive substrate, wherein each LED unit can be individually driven by the drive substrate, and the plurality of LED units have a plurality of corresponding LED mesas on a one-to-one basis; a first fence structure, wherein the first fence structure is provided with a plurality of first grid holes, the plurality of first grid holes respectively surrounding the plurality of LED mesas, and the first fence structure is higher than the plurality of LED units; and an optical layer arranged on the first fence structure, wherein each LED mesa and the optical layer form a cavity region at the corresponding first grid hole. The cavity regions are formed by a simple process, and heat conduction from the LED units to a light conversion structure above is reduced, thereby not only prolonging the service life of the micro-display chip, but also reducing the manufacturing cost.

Description

Micro LED micro display chip and preparation method thereof Cross-reference to related disclosures

[0001] The present disclosure claims priority to the Chinese patent publication with the application number 202510230716.9, the title of which is “Micro LED micro display chip and preparation method thereof”, filed on February 28, 2025, with the Chinese Patent Office, the entire content of which is incorporated herein by reference. TECHNICAL FIELD

[0002] The present disclosure relates to the technical field of display chip, in particular to a Micro LED micro display chip and a preparation method thereof.

[0003] Micro LED, also known as micro light emitting diode, is a micro LED light emitting unit array integrated on an active addressing driving substrate to realize individual control and lighting, thereby outputting display images. Full-color micro display has a wide range of application fields, especially near-eye display (including AR, VR, etc.).

[0004] The traditional full-color micro display form directly sets the light conversion structure on the light emitting structure. Since the heat of the LED unit is directly conducted to the light conversion structure, the aging and failure of the light conversion structure are accelerated, which limits the service life of the full-color micro display device.

[0005] In order to limit the heat transfer of the LED unit to the light conversion structure, the Chinese patent document CN119050126A discloses a display device and a forming method thereof. A heat insulation structure is provided on the planarization layer, and the heat insulation structure includes an air-supported unit. In order to form the air-supported unit, a sacrificial layer is formed on the planarization layer, a predetermined number of holes are formed on the sacrificial layer, the holes expose the surface of the planarization layer, a support leg is formed in the hole, and an air-supported layer is formed on the sacrificial layer. By removing the sacrificial layer, the air-supported layer is suspended on the support leg. In order to form a heat insulation cavity inside the air-supported unit, a heat conduction layer is sealed between adjacent air-supported units to determine the plugging of the side surface of the air-supported unit. The Chinese patent document CN119050126A forms a complex air-supported unit on the planarization layer, and the overall thickness of the micro display device structure is large, and the preparation process is complex, which is not conducive to the development of chip products with small size and low cost.

[0006] A Micro LED micro display chip is disclosed in Chinese patent document CN119050236A. A plurality of groups of through holes are formed in a first transmissive reflective layer, and each group of through holes is arranged circumferentially around the edge of a corresponding grid hole. The through holes penetrate the first transmissive reflective layer and extend into the grid hole, so that the etching liquid can flow into the grid hole through the through holes to etch and hollow out the sacrificial layer in the grid hole by the etching liquid. The through holes are filled with a heat-conducting metal unit, so that a cavity of the middle control structure can be formed between the first transmissive reflective layer and the LED unit. In order to form the cavity, Chinese patent CN119050236A not only needs to break the integrity of the first transmissive reflective layer to form a plurality of groups of through holes in the first transmissive reflective layer, but also needs to use a heat-conducting metal unit to close the through holes to form the cavity. The above complex process greatly increases the production cost. Since the above complex process requires very high precision, the yield is low.

[0007] To solve the above problems, the embodiments of the present disclosure provide a Micro LED micro display chip and a preparation method thereof. The cavity structure is formed on the LED unit by a simple process, the heat conduction of the LED unit to the light conversion structure is reduced, the service life of the micro display chip is improved, and the manufacturing cost is reduced.

[0008] The embodiments of the present disclosure adopt the following technical solutions:

[0009] In a first aspect, the embodiments of the present disclosure provide a Micro LED micro display chip, comprising: a driving substrate and a light emitting structure arranged on the driving substrate;

[0010] The light emitting structure comprises: a plurality of LED units, a first fence structure, and an optical layer;

[0011] The plurality of LED units are arranged on the driving substrate with a spacing between each other, and each LED unit can be individually driven by the driving substrate. The plurality of LED units have a one-to-one correspondence with a plurality of LED mesas;

[0012] The first fence structure has a plurality of first grid holes, and the plurality of first grid holes respectively surround the plurality of LED mesas. The first fence structure is higher than the plurality of LED units;

[0013] The optical layer is arranged on the first fence structure. The LED mesa and the optical layer form a cavity region at the corresponding first grid hole.

[0014] Optionally, the first fence structure comprises a first light-blocking base and a first light-reflecting layer arranged on the surface of the first light-blocking base;

[0015] The first light-blocking base has a plurality of first grid holes;

[0016] The first light-reflecting layer is arranged at least on the sidewall of the first grid hole.

[0017] Optionally, the optical layer comprises: a transparent transition layer disposed on the first fence structure, and a transmissive reflective layer disposed on the transparent transition layer.

[0018] The optical layer is configured to transmit light of the plurality of LED units.

[0019] Optionally, the transparent transition layer has a via hole at a position corresponding to each first grid hole.

[0020] Optionally, the transmissive reflective layer is a distributed Bragg reflector.

[0021] Optionally, the transparent transition layer is made of a transparent inorganic oxide.

[0022] Optionally, the diameter of the via hole is less than 0.5 μm.

[0023] Optionally, the micro display chip further comprises: a light conversion structure disposed on the optical layer.

[0024] The light conversion structure comprises: a second fence structure and a plurality of light conversion units.

[0025] The second fence structure has a plurality of second grid holes, and the plurality of second grid holes correspond one-to-one to the plurality of first grid holes.

[0026] The plurality of light conversion units are respectively disposed in the plurality of second grid holes.

[0027] Optionally, the second fence structure comprises: a second light blocking base and a second light reflecting layer disposed on the surface of the second light blocking base.

[0028] The second light blocking base has a plurality of second grid holes.

[0029] The second light reflecting layer is disposed at least on the sidewall of the second grid hole.

[0030] Optionally, the plurality of light conversion units at least comprise: a first light conversion unit and a second light conversion unit.

[0031] The first light conversion unit converts light passing through the optical layer into first color light.

[0032] The second light conversion unit converts light passing through the optical layer into second color light.

[0033] Optionally, the plurality of light conversion units further comprise: a transparent unit.

[0034] The transparent unit transmits light passing through the optical layer.

[0035] Optionally, the plurality of light conversion units further comprise: a third light conversion unit.

[0036] The third light conversion unit converts light passing through the optical layer into third color light.

[0037] In a second aspect, the embodiments of the present disclosure provide a preparation method of a Micro LED micro display chip, comprising:

[0038] providing a driving substrate, and forming a light-emitting structure on the driving substrate;

[0039] wherein the forming of the light-emitting structure on the driving substrate comprises:

[0040] forming a plurality of LED units; wherein the plurality of LED units are arranged on the driving substrate in a spaced manner, and each LED unit can be driven individually by the driving substrate, and the plurality of LED units have a one-to-one corresponding plurality of LED mesa;

[0041] forming a first fence structure; wherein the first fence structure has a plurality of first grid holes, and the plurality of first grid holes respectively surround the plurality of LED mesa, and the first fence structure is higher than the plurality of LED units;

[0042] forming an optical layer; wherein the optical layer is formed on the first fence structure, and the LED mesa and the optical layer form a cavity region at the corresponding first grid hole;

[0043] wherein the forming of the optical layer comprises:

[0044] adopting a filler to perform a planarization treatment on the first fence structure;

[0045] forming a transparent transition material layer on the planarized first fence structure;

[0046] etching a position corresponding to each first grid hole of the transparent transition material layer to form a via hole, and obtaining a transparent transition layer;

[0047] removing the filler of each LED mesa and the transparent transition layer at the corresponding first grid hole through the via hole;

[0048] forming a transmissive reflective layer on the transparent transition layer.

[0049] Optionally, the forming of the first fence structure comprises:

[0050] forming a first light-blocking base material layer on the plurality of LED units;

[0051] etching the first light-blocking base material layer to form a plurality of first grid holes surrounding the plurality of LED mesa, and obtaining a first light-blocking base;

[0052] forming a first light-reflecting material layer on the plurality of LED mesa and the first light-blocking base;

[0053] etching the first light-reflecting material layer to form a first light-reflecting layer at least on the sidewall of the first grid hole.

[0054] Optionally, the method further comprises:

[0055] forming the light conversion structure;

[0056] wherein the forming the light conversion structure comprises:

[0057] forming a second fence structure on the optical layer; wherein the second fence structure has a plurality of second grid holes, and the plurality of second grid holes one-to-one correspond to the plurality of first grid holes;

[0058] forming a plurality of light conversion units in the plurality of second grid holes.

[0059] Optionally, the forming the second fence structure on the optical layer comprises:

[0060] forming a second light-blocking matrix material layer on the optical layer;

[0061] etching the second light-blocking matrix material layer to form a plurality of second grid holes corresponding to the first grid holes, to obtain a second light-blocking matrix;

[0062] forming a second light-reflecting material layer on the optical layer and the second light-blocking matrix;

[0063] etching the second light-reflecting material layer to form a second light-reflecting layer at least on the sidewalls of the second grid holes.

[0064] Optionally, the forming the plurality of light conversion units in the plurality of second grid holes comprises:

[0065] filling a light conversion material in the plurality of second grid holes; wherein the light conversion material at least comprises: a first light conversion material and a second light conversion material;

[0066] filling the first light conversion material in part of the second grid holes to form a first light conversion unit, to convert light passing through the optical layer into first color light;

[0067] filling the second light conversion material in part of the second grid holes to form a second light conversion unit, to convert light passing through the optical layer into second color light.

[0068] The chip provided by the present disclosure comprises: a driving substrate and a light-emitting structure arranged on the driving substrate; the light-emitting structure comprises: a plurality of LED units arranged at intervals on the driving substrate, each LED unit can be individually driven by the driving substrate, and the plurality of LED units have a plurality of LED mesa corresponding one-to-one; a first fence structure, the first fence structure has a plurality of first grid holes, and the plurality of first grid holes respectively surround the plurality of LED mesa, and the first fence structure is higher than the plurality of LED units; an optical layer arranged on the first fence structure, and the LED mesa and the optical layer form a cavity region at the corresponding first grid hole.

[0069] The Micro LED micro display chip provided by the present disclosure forms a cavity region at the corresponding first grid hole through the LED mesa and the optical layer, and the air in the cavity region has extremely low thermal conductivity (the thermal conductivity of air is only 0.024 W / m·K in a closed state), which reduces the heat conduction of the LED unit to the light conversion structure above, and effectively improves the service life of the Micro LED micro display chip.

[0070] The Micro LED micro display chip provided by the present disclosure can form a cavity region through the first grid hole and the optical layer, and the manufacturing process is simple, and no complex and precise processing is required, so the product yield is high.

[0071] The Micro LED micro display chip provided by the present disclosure has lower production cost and is suitable for large-scale production.

[0072] FIG. 1 shows a structural schematic diagram of a Micro LED micro display chip according to one embodiment of the present disclosure;

[0073] FIG. 2 shows a structural schematic diagram of a Micro LED micro display chip according to another embodiment of the present disclosure;

[0074] FIG. 3 shows a flowchart of a preparation method of a Micro LED micro display chip according to one embodiment of the present disclosure;

[0075] FIG. 4 shows a structural schematic diagram after forming a plurality of LED units according to one embodiment of the present disclosure;

[0076] FIG. 5 shows a structural schematic diagram after forming a first light-blocking base material layer according to one embodiment of the present disclosure;

[0077] FIG. 6 shows a structural schematic diagram after obtaining a first light-blocking base according to one embodiment of the present disclosure;

[0078] FIG. 7 shows a structural schematic diagram after forming a first light-reflecting material layer according to one embodiment of the present disclosure;

[0079] FIG. 8 shows a schematic diagram of forming a first light-reflecting layer according to one embodiment of the present disclosure;

[0080] FIG. 9 shows a structural schematic diagram after planarization processing according to one embodiment of the present disclosure;

[0081] FIG. 10 shows a structural schematic diagram after forming a transparent transition material layer according to one embodiment of the present disclosure;

[0082] FIG. 11 shows a structural schematic diagram after obtaining a transparent transition layer according to one embodiment of the present disclosure;

[0083] FIG. 12 illustrates a schematic diagram of a structure after filler removal according to an embodiment of the present disclosure;

[0084] FIG. 13 illustrates a schematic diagram of a structure after forming a transmissive reflective layer according to an embodiment of the present disclosure;

[0085] FIG. 14 illustrates a schematic diagram of a structure after forming a second barrier structure according to an embodiment of the present disclosure;

[0086] FIG. 15 illustrates a schematic diagram of a structure after forming a plurality of light conversion units according to an embodiment of the present disclosure;

[0087] FIG. 16 illustrates another schematic diagram of a structure after forming a plurality of light conversion units according to an embodiment of the present disclosure.

[0088] Exemplary embodiments of the present disclosure will be described in greater detail below. It should be understood, however, that the present disclosure can be practiced in various forms without being limited to the embodiments set forth herein. Rather, these embodiments are provided so that the present disclosure will be thorough and complete, and will fully convey the scope of the present disclosure to those skilled in the art.

[0089] The present disclosure provides many different embodiments or examples for implementing different structures of the present disclosure. For the purpose of simplicity, the present disclosure will be described in terms of specific examples as illustrated in the drawings. Of course, it is contemplated that where features do not necessarily add to the functionality or understanding of the present disclosure, various implicit combinations can be implied by those skilled in the art. Additionally, it will be appreciated that the various identified components and arrangements can be combined in various ways without departing from the spirit and scope of the present disclosure. Furthermore, the present disclosure provides examples of various specific processes and materials. However, one skilled in the art will recognize that other processes and / or materials can be used without departing from the spirit and scope of the present disclosure.

[0090] In general, the terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the present disclosure. For example, as used herein, the singular forms "a", "an" and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It will be further understood that the terms "comprises" and / or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and / or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and / or groups thereof. As used herein, the term "and / or" includes any and all combinations of one or more of the associated listed items. As used herein, the term "based on" is used to describe one or more factor(s) to which other operations are based, at least in part, but which need not be explicitly combined with one or more other operations in determining the desired operations. Additionally, some embodiments are described as processes defined by a set of operations to be performed at various times. These processes can be referred to as programs, methods, algorithms, and / or the like. However, it will be understood that the processes defined by these operations need not be performed at the same times, nor via the same processing module, computer, and / or other device.

[0091] It should be noted that in the description of the present disclosure, the meanings of the terms "on", "over", "above", "on top of", and the like should be interpreted in the broadest manner, meaning that the description including these terms is interpreted as "the component can be disposed on another component in a direct contact manner, or there can be an intermediate component or layer between the components".

[0092] For ease of description, the present disclosure can also use spatial relative terms such as "under", "below", "underneath", "beneath", "upper", "lower", and the like to describe the relationship of one component to another component shown in the drawings, in addition to the orientation described in the drawings, the spatial relative terms are also intended to cover different orientations of the device in use or operation. The device can be oriented in other manners, and the spatial relative description used in the present disclosure can be interpreted accordingly.

[0093] FIG. 1 shows a structural schematic diagram of a Micro LED micro display chip according to an embodiment of the present disclosure. In FIG. 1, the lateral direction can correspond to the cross-sectional extension direction of the Micro LED micro display chip, and the longitudinal direction can correspond to the ideal light beam propagation direction of the Micro LED micro display chip.

[0094] Referring to FIG. 1, the micro display chip of the present embodiment can include a driving substrate 1 and a light emitting structure 2 disposed on the driving substrate 1.

[0095] The light emitting structure 2 includes a plurality of LED units 21, a first fence structure 22, and an optical layer 23. The plurality of LED units 21 are arranged on the driving substrate 1 with a spacing therebetween, and each LED unit 21 can be individually driven by the driving substrate 1, and the plurality of LED units 21 have a one-to-one correspondence with a plurality of LED mesas. The first fence structure 22 has a plurality of first grid holes, and the plurality of first grid holes respectively surround the plurality of LED mesas, and the first fence structure 22 is higher than the plurality of LED units 21. The optical layer 23 is disposed on the first fence structure 22, and the LED mesa and the optical layer 23 form a cavity region at the corresponding first grid hole.

[0096] The driving substrate 1 can include a base 11, a driving circuit, and a plurality of contacts connected with the driving circuit. The driving substrate 1 can be provided with a circuit layer including a silicon-based CMOS (Complementary Metal Oxide Semiconductor) backplane, a TFT glass substrate, or a thin-film field effect transistor, etc. to constitute the driving circuit. The material of the base 11 can include a semiconductor material such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, cobalt phosphide, etc. and can also include a non-conductive material such as glass, plastic, sapphire wafer, etc. The driving substrate 1 can be bonded with each LED unit 21 through the contacts, and each LED unit 21 can be integrally arranged above the corresponding contact.

[0097] The plurality of LED units 21 can be arranged on the driving substrate 1 in a regular or irregular manner as pixels of the micro display chip. The driving substrate 1 can refer to the control panel of the plurality of LED units 21. The driving substrate 1 generates a driving signal based on the image to be displayed and applies it to the plurality of LED units 21, so that each LED unit 21 independently releases a light beam in response to the driving signal.

[0098] The LED unit 21 can be a micro light emitting diode or a micro organic light emitting diode. The micro light emitting diode is formed based on inorganic semiconductor material, for example, the inorganic semiconductor material can be gallium nitride, aluminum gallium nitride, gallium arsenide, aluminum gallium indium phosphide, etc. The micro organic light emitting diode is formed based on organic material, for example, the organic material can be small molecules, polymers, phosphorescent materials, etc.

[0099] Each LED unit 21 has an LED mesa, which can have a trapezoidal structure. That is, the side wall of the LED mesa can be an inclined surface, and the included angle between the side wall of the LED mesa and the top surface of the LED mesa can be an obtuse angle, thereby improving the light condensing effect of the LED unit 21. Of course, the LED mesa can also have a columnar structure, in which case the included angle between the side wall of the LED mesa and the top surface of the LED mesa is a right angle.

[0100] The Micro LED micro display device can be a common cathode structure, or a common anode structure, or independent.

[0101] In some optional embodiments, each LED unit 21 can include a first doped semiconductor layer 211, a light-emitting layer 212, and a second doped semiconductor layer 213 arranged in a stack. A passivation layer 214 covers the light-emitting surface and the side surface of each LED unit 21 and has an opening on the light-emitting surface of each LED unit 21, while the passivation layer 214 exposes the contacts of the driving substrate 1. Each LED unit 21 further includes a first electrode 216 and a second electrode 217, and the first doped semiconductor layer 211 can further include a bonding layer 215 between the first doped semiconductor layer 211 and the first electrode 216. The first doped semiconductor layer 211 is connected to the corresponding first contact 13 of the driving substrate 1 through the bonding layer 215 and the first electrode 216, and the second doped semiconductor layer 213 is connected to the corresponding second contact 12 of the driving substrate 1 through the second electrode 217.

[0102] When the first electrode 216 of each LED unit 21 is a common electrode, the Micro LED micro display device is a common anode structure; when the second electrode 217 of each LED unit 21 is a common electrode, the Micro LED micro display device is a common cathode structure. The case shown in FIG. 1 is a common anode structure.

[0103] The first doped semiconductor layer 211 can be a p-type GaN or InGaN layer formed by doping or ion implantation, etc., and can have a multi-layer structure. The second doped semiconductor layer 213 can be an n-type GaN or InGaN layer formed by doping or ion implantation, etc., and can also have a multi-layer structure. The light-emitting layer 212 is a layer in which holes provided by the first doped semiconductor layer 211 and electrons provided by the second doped semiconductor layer 213 recombine to output light of a specific wavelength, and can have a single quantum well structure or a multi-quantum well (MQW) structure, and can also have a stack of well layers and barrier layers alternately.

[0104] The material of the passivation layer 214 can include inorganic materials or organic materials. The inorganic materials can include, but are not limited to, any one or a combination of several of silicon dioxide, aluminum oxide, zirconium dioxide, titanium dioxide, silicon nitride, hafnium oxide; and the organic materials can include any one or a combination of several of black matrix photoresist, color filter photoresist, polyimide, bank photoresist, overcoat photoresist, near-ultraviolet negative photoresist, and benzene propyl cyclobutene.

[0105] The materials of the first electrode 216 and the second electrode 217 can be metal materials or metal alloy materials, including indium tin oxide, chromium, platinum gold, gold, aluminum, germanium, tin, indium, copper, or titanium, etc.

[0106] The first fence structure 22 surrounds the plurality of LED platforms. The first fence structure 22 has a plurality of first fence holes corresponding to the plurality of LED units 21. That is, the plurality of first fence holes can be arranged in a regular or irregular manner according to the arrangement of the plurality of LED units 21. In order to improve the uniformity of light emitted by each LED unit 21, each LED unit 21 can be arranged at the center of the corresponding first fence hole.

[0107] The sidewall of the first fence hole can be inclined, that is, the included angle between the sidewall of the first fence hole and the top surface of the first fence structure 22 is obtuse. Referring to the direction away from the driving substrate 1 shown in FIG. 1, the cross-sectional size of the first fence hole can gradually increase. Generally, the cross section can be a circular cross section or a square cross section, and of course the cross section can also be an irregular cross section. The structure of the first fence hole can be a bowl-shaped structure or a horn-shaped structure, so that the emitted light of the LED unit 21 can be collimated. When the sidewall of the LED platform is inclined and the sidewall of the first fence hole is also inclined, the light can be reflected multiple times on the inclined surfaces of the two, thereby improving the luminous brightness of the LED unit 21.

[0108] The height of the first fence structure 22 is higher than that of the plurality of LED units 21. That is, the height of the top surface of the first fence structure 22 is higher than the height of the top surface of each LED unit 21.

[0109] In some optional embodiments, the first fence structure 22 includes a first light-blocking base 221 and a first light-reflecting layer 222 arranged on the surface of the first light-blocking base 221. The first light-blocking base 221 has a plurality of first fence holes. The first light-reflecting layer 222 is arranged at least on the sidewall of the first fence hole.

[0110] The first fence structure 22 can be formed by using a first light-blocking base material. The first light-blocking base material is arranged with a first fence hole at a position corresponding to each LED unit 21, and the first light-reflecting layer 222 is arranged at least on the sidewall of the first fence hole. The first light-reflecting layer 222 can also be arranged on the top surface of the first light-blocking base 221.

[0111] The material of the first light-blocking base 221 can include, but is not limited to, organic resin, organic black matrix photoresist, color filter photoresist, or polyimide, etc. The material of the first light-reflecting layer 222 can include, but is not limited to, organic material or inorganic material. The organic material can be high-reflective organic paint, and the inorganic material can be metal material such as aluminum, copper, silver, etc.

[0112] The first reflective layer 222 in the first fence structure 22 can effectively prevent light leakage from the sidewall of each LED unit 21, thereby effectively preventing light crosstalk between adjacent LED units 21. Meanwhile, the first fence structure 22 also plays a role in heat conduction, preventing the heat generated by the LED material from being concentrated and conducted to the fluorescent material.

[0113] In some optional embodiments, an etching blocking layer can be covered on the plurality of LED units 21 to prevent etching damage to the plurality of LED mesas.

[0114] The etching blocking layer can be a continuous film layer structure located between the first fence structure 22 and the plurality of LED units 21. The etching blocking layer can transmit the light emitted by the plurality of LED units 21, and therefore the etching blocking layer should have sufficient transparency. Generally, the material of the etching blocking layer can include, but is not limited to, silicon dioxide, silicon nitride, or aluminum trioxide, etc.

[0115] An optical layer 23 is arranged on the first fence structure 22. For each LED unit 21, the LED mesa, the optical layer 23, and the corresponding first fence hole form a closed cavity region. The air in the cavity region has very low thermal conductivity. In a closed state, the thermal conductivity of air is only 0.024 W / m·K, and therefore, through the closed cavity region, the heat conduction of the LED material to the fluorescent material above is reduced, effectively improving the service life of the Micro LED micro display chip.

[0116] In some optional embodiments, the optical layer 23 includes a transparent transition layer 231 arranged on the first fence structure 22 and a transmissive reflective layer 232 arranged on the transparent transition layer 231. The optical layer 23 is used to transmit the light of the plurality of LED units 21.

[0117] In order to form a closed cavity region between the optical layer 23 and the LED mesa at the corresponding first fence hole, a filler 233 needs to be used to planarize the first fence structure 22 before forming the optical layer 23, and then the filler 233 is removed to form a cavity structure in the process of forming the optical layer 23.

[0118] Therefore, after the first fence structure 22 is planarized, the transparent transition layer 231 is formed on the planarized first fence structure 22, the transparent transition layer 231 is etched at a position corresponding to each first fence hole to form a via, and the transmissive reflective layer 232 is formed on the transparent transition layer 231 after the filler 233 is removed through the via, thereby realizing a closed cavity structure. That is, the transparent transition layer 231 is provided with a via at a position corresponding to each first fence hole.

[0119] The material of the transparent transition layer 231 can be a transparent inorganic oxide material, such as silicon dioxide, aluminum trioxide, etc. Meanwhile, the thickness of the transparent transition layer 231 can be as thin as possible.

[0120] In order to meet the functional requirements of removing the filler 233 and supporting the transmission reflection layer 232, the diameter of the via hole is not greater than 0.5 μm. The via hole can be opened at the center position of the transparent transition layer 231 corresponding to each first fence hole.

[0121] The transmission reflection layer 232 can be a distributed Bragg reflector (DBR) layer. The distributed Bragg reflector layer can be composed of a plurality of different refractive index materials alternately stacked. The material used by the transmission reflection layer 232 is usually a semiconductor material, such as but not limited to including silicon, indium nitride, gallium nitride, aluminum gallium nitride, and iron nickel phosphide, etc. These semiconductor materials have different refractive indexes, and by stacking them together according to a specific design, reflection of light of a specific wavelength can be achieved. By adjusting the number of layers and composition of the material, transmission of light of different wavelengths can be achieved.

[0122] The function of the optical layer 23 includes transmitting the light emitted by the plurality of LED units 21. In the case where the micro display chip further includes the light conversion structure 3 disposed on the optical layer 23, the function of the optical layer 23 further includes reflecting the light converted in color by the light conversion structure 3.

[0123] FIG. 2 shows a structural schematic diagram of a Micro LED micro display chip according to another embodiment of the present disclosure.

[0124] Referring to FIG. 2, the micro display chip of the present embodiment further includes the light conversion structure 3 disposed on the optical layer 23 on the basis of the micro display chip proposed in the previous embodiment. The light conversion structure 3 includes the second fence structure 31 and the plurality of light conversion units 32. The second fence structure 31 has a plurality of second fence holes, and the plurality of second fence holes correspond one-to-one to the plurality of first fence holes. The plurality of light conversion units 32 are respectively disposed in the plurality of second fence holes.

[0125] The second fence structure 31 has a plurality of second fence holes corresponding one-to-one to the first fence holes. That is, according to the arrangement mode of the plurality of first fence holes, the plurality of second fence holes can be arranged in a regular or irregular manner.

[0126] The sidewall of the second grid hole can be an inclined plane, meaning the angle between the sidewall of the second grid hole and the top surface of the second grid structure 31 is an obtuse angle. Referring to Figure 2, in the direction away from the driving substrate 1, the cross-sectional size of the second grid hole can gradually increase. Generally, this cross-section can be a circular cross-section or a square cross-section, and of course, it can also be an irregularly shaped cross-section. The structure of the second grid hole can be a bowl-shaped structure or a trumpet-shaped structure.

[0127] In some alternative embodiments, the second fence structure 31 includes: a second light-blocking substrate 311 and a second reflective layer 312 disposed on the surface of the second light-blocking substrate 311. The second light-blocking substrate 311 has a plurality of second grid holes. The second reflective layer 312 is disposed at least on the sidewalls of the second grid holes.

[0128] The second grid structure 31 may be formed using a second light-blocking substrate material. The second light-blocking substrate material is provided with second grid holes at positions corresponding to each first grid hole, and a second reflective layer 312 is provided at least on the sidewalls of the second grid holes. The second reflective layer 312 may also be provided on the top surface of the second light-blocking substrate 311.

[0129] The material of the second light-blocking substrate 311 may include, but is not limited to, organic resin, organic black matrix photoresist, color filter photoresist, or polyimide. The material of the second reflective layer 312 may include, but is not limited to, organic or inorganic materials. Organic materials may be highly reflective organic coatings, and inorganic materials may be metallic materials such as aluminum, copper, or silver.

[0130] The second reflective layer 312 in the second fence structure 31 can effectively prevent the light entering the light conversion unit 32 from affecting the light of adjacent light conversion units 32, reduce crosstalk between them, and improve the display effect.

[0131] Multiple light conversion units 32 are respectively disposed in multiple second grid holes, such that each light conversion unit 32 is disposed on a corresponding LED unit 21. Each light conversion unit 32 fills at least part or all of the corresponding second grid hole.

[0132] In some optional embodiments, the plurality of light conversion units 32 include at least: a first light conversion unit 321 and a second light conversion unit 322. The first light conversion unit 321 converts the light passing through the optical layer 23 into light of a first color; the second light conversion unit 322 converts the light passing through the optical layer 23 into light of a second color.

[0133] Among the multiple optical conversion units 32, some optical conversion units 32 are first optical conversion units 321, and some optical conversion units 32 are second optical conversion units 322. That is, the first optical conversion unit 321 and the second optical conversion unit 322 are respectively disposed in different second grid apertures.

[0134] The material of the light conversion unit 32 includes photoresist and wavelength conversion particles, which may be, but are not limited to, quantum dots and / or phosphors. The photoresist includes, but is not limited to, overcoat photoresist, SU8 (near-ultraviolet negative photoresist), benzocyclobutene (BCB), etc., and may also be silicon dioxide, aluminum oxide, silicon nitride, etc. The phosphor may be yttrium aluminum garnet, cerium phosphor, (oxy)nitride phosphor, silicate phosphor, and Mn4+ activated fluoride phosphor, etc. The quantum dots may include one or more combinations of CdSe, CdS, CdZnSe, CdZnS, CdZnSeS, ZnSeS, ZnSe, CuInS, CuInSe, InP, InZnP, and perovskite quantum dots.

[0135] The light emitted by LED unit 21 passes through optical layer 23 and enters first light conversion unit 321, where it is converted into first color light. The first color light can be red light, and in this case, first light conversion unit 321 uses a red wavelength conversion material. The light emitted by LED unit 21 passes through optical layer 23 and enters second light conversion unit 322, where it is converted into second color light. The second color light can be green light, and in this case, second light conversion unit 322 uses a green wavelength conversion material.

[0136] In some alternative embodiments, the plurality of light conversion units 32 further include a transparent unit 324; the transparent unit 324 transmits light through the optical layer 23.

[0137] In some cases, the light emitted by LED unit 21 is blue light. In this case, it is sufficient for transparent unit 324 to transmit the blue light emitted by LED unit 21. Therefore, transparent unit 324 is provided in the second grid hole where the first light conversion unit 321 and the second light conversion unit 322 are not provided, so that the blue light emitted by LED unit 21 can be directly transmitted.

[0138] In some alternative embodiments, the plurality of light conversion units 32 may further include a third light conversion unit 323; the third light conversion unit 323 converts the light passing through the optical layer 23 into a third color light.

[0139] In some cases, the light emitted by LED unit 21 is not blue light. In this case, the light emitted by LED unit 21 enters the third light conversion unit 323 after passing through optical layer 23, and is converted into a third color light within the third light conversion unit 323. The third color light can be blue light, and in this case, the third light conversion unit 323 uses a blue wavelength conversion material.

[0140] The first, second, and third colors of light are all different. The first, second, and third colors can also be set to other colors according to actual needs. By setting multiple light conversion units 32, full-color display of the Micro LED microdisplay chip can be achieved.

[0141] Figure 3 shows a schematic flowchart of a method for fabricating a Micro LED microdisplay chip according to an embodiment of this disclosure. Referring to Figure 3, the fabrication method proposed in this disclosure includes the following steps:

[0142] Step S1, provide driving substrate 1;

[0143] Step S2: Form a light-emitting structure 2 on the driving substrate 1.

[0144] Step S2, forming a light-emitting structure 2 on the driving substrate 1, includes:

[0145] Step S21: A plurality of LED units 21 are formed; wherein, the plurality of LED units 21 are arranged at intervals on the driving substrate 1, and each LED unit 21 can be driven individually by the driving substrate 1, and the plurality of LED units 21 have a plurality of corresponding LED mesa surfaces.

[0146] Step S22: A first fence structure 22 is formed; wherein the first fence structure 22 has a plurality of first grid holes, the plurality of first grid holes surround a plurality of LED platforms respectively, and the first fence structure 22 is higher than a plurality of LED units 21.

[0147] Step S23: Forming an optical layer 23; wherein the optical layer 23 is formed on the first grid structure 22, and the LED mesa and the optical layer 23 form a cavity region at the corresponding first grid hole; wherein forming the optical layer 23 includes: planarizing the first grid structure 22 with filler 233; forming a transparent transition material layer 231a on the planarized first grid structure 22; etching the transparent transition material layer 231a at the position corresponding to each first grid hole to form a via, thereby obtaining the transparent transition layer 231; removing the filler 233 at the corresponding first grid hole of each LED mesa and the transparent transition layer 231 through the via; and forming a transmission and reflection layer 232 on the transparent transition layer 231.

[0148] Figures 4 to 16 illustrate different stages in the fabrication process of Micro LED microdisplay chips. Referring to Figures 4 to 16, a detailed description of the methods for fabricating Micro LED microdisplay chips is provided.

[0149] Figure 4 shows a schematic diagram of the structure after forming multiple LED units 21. In some embodiments of this disclosure, referring to Figure 4, forming multiple LED units 21 includes: forming an LED epitaxial layer on a driving substrate 1; etching the LED epitaxial layer according to a MESA pattern designed using a patterned mask; forming an intermediate body; forming a passivation layer 214 on the sidewalls of the intermediate body; and forming a second electrode 217 on the passivation layer 214, the second electrode 217 connecting the top surface of the LED epitaxial layer and the second contact 12 of the driving substrate 1, thereby forming multiple LED units 21.

[0150] A substrate is provided, on which an LED epitaxial layer is grown, and a first bonding layer is formed on the LED epitaxial layer. The first bonding layer can be used to bond the LED epitaxial layer on the substrate to the driving substrate 1 proposed later.

[0151] A driving substrate 1 is provided. The driving substrate 1 may be provided with a circuit layer including a silicon-based CMOS backplane, a TFT glass substrate, or a thin-film field-effect transistor, etc., to form a driving circuit. The driving substrate 1 also includes a plurality of contacts connected to the driving circuit. The plurality of contacts include a first contact 13 and a second contact 12. A first electrode 216 and a second bonding layer are formed on the driving substrate 1. The first electrode 216 and the first contact 13 are connected, and the second bonding layer can be used to bond the driving substrate 1 and the LED epitaxial layer on the substrate.

[0152] The LED epitaxial layer, the first bonding layer, the first electrode 216, and the second bonding layer can be formed by deposition.

[0153] The LED epitaxial layer is bonded to the driving substrate 1 by metal bonding the first bonding layer and the second bonding layer to form a bonding layer 215.

[0154] The substrate is peeled off from the LED epitaxial layer. The substrate peeling methods include, but are not limited to, laser peeling, dry etching, wet etching, mechanical polishing, etc.

[0155] Thinning operations are performed on the LED epitaxial layer, including dry etching, wet etching, or mechanical polishing.

[0156] Based on the MESA pattern designed using a patterned mask, the bonded LED epitaxial layer is etched, and then the bonding layer 215 is etched to form multiple intermediates. Each intermediate includes a first doped semiconductor layer 211, a light-emitting layer 212, and a second doped semiconductor layer 213. The etching can be performed using dry or wet methods.

[0157] A passivation layer 214 is deposited on the side surface of the intermediate, and a second electrode 217 is deposited on the passivation layer 214, such that the second electrode 217 is connected to the second doped semiconductor layer 213 and the second contact 12. This forms a plurality of LED units 21.

[0158] Figures 5 to 8 show schematic diagrams of the structure forming the first fence structure 22. In some embodiments of this disclosure, referring to Figures 5 to 8, forming the first fence structure 22 includes: forming a first light-blocking substrate material layer 221a on a plurality of LED units 21; etching the first light-blocking substrate material layer 221a to form a plurality of first grid holes surrounding the plurality of LED mesa, thereby obtaining the first light-blocking substrate 221; forming a first reflective material layer 222a on the plurality of LED mesa and the first light-blocking substrate 221; and etching the first reflective material layer 222a to form a first reflective layer 222 at least on the sidewalls of the first grid holes.

[0159] A first light-blocking substrate material layer 221a can be formed on multiple LED units 21, as shown in Figure 5.

[0160] The first light-blocking substrate material layer 221a is etched to form a first light-blocking substrate 221 with multiple first grid holes. The multiple first grid holes surround multiple LED mesa surfaces, and a recess is formed between the LED mesa surface and the corresponding first grid hole, as shown in Figure 6.

[0161] A first reflective material layer 222a is formed on multiple LED platforms and a first light-blocking substrate 221. The first reflective material layer 222a can be deposited by atomic layer deposition (ALD), chemical vapor deposition (CVD), evaporation, sputtering, or other methods, as shown in Figure 7.

[0162] The first reflective material layer 222a on multiple LED platforms is etched to form the first reflective layer 222 on the sidewalls of the first grid aperture and the top surface of the first light-blocking substrate 221. Etching can be performed using dry etching methods, including but not limited to ion beam etching (IBE) and inductively coupled plasma etching (ICP). Using dry etching allows for full-surface etching after the first reflective material layer 222a is deposited, ensuring that the first reflective material on multiple LED platforms is completely etched away. Simultaneously, during the etching process, the first reflective material layer 222a undergoes a plasma redeposition effect, resulting in a thickening of the first reflective material layer 222a on the sidewalls of the first grid aperture, enhancing the reflective effect and strengthening the stability of the first grid structure 22. (See Figure 8.)

[0163] In some embodiments of this disclosure, before forming the first fence structure 22, the fabrication method may further include: forming an etching barrier layer; wherein the etching barrier layer covers a plurality of LED units 21 to prevent damage to the plurality of LED mesa surfaces when etching the first fence structure 22.

[0164] In some embodiments of this disclosure, before etching the first reflective material layer 222a on the plurality of LED platforms, the preparation method may further include: forming a sacrificial coating on the first reflective material layer 222a; removing the sacrificial coating exposed on the first grid holes; etching the first reflective material layer 222a on the plurality of LED platforms; and removing the remaining sacrificial coating.

[0165] Figures 9 to 13 show schematic diagrams of the structure forming the optical layer 23. In some embodiments of this disclosure, referring to Figures 9 to 13, forming the optical layer 23 includes: planarizing the first grid structure 22 with filler 233; forming a transparent transition material layer 231a on the planarized first grid structure 22; etching the transparent transition material layer 231a at the position corresponding to each first grid hole to form vias, thereby obtaining the transparent transition layer 231; removing the filler 233 at the corresponding first grid hole of each LED mesa and the transparent transition layer 231 through the vias; and forming a transmission and reflection layer 232 on the transparent transition layer 231.

[0166] The filler 233 is used to fill each of the first grid holes of the first fence structure 22. The filling height is the top of the grid network of the first fence structure 22. The filler 233 can be an organic resin material, as shown in Figure 9.

[0167] A transparent transition material layer 231a is formed on the planarized first fence structure 22. The transparent transition material layer 231a can be made of a transparent inorganic oxide material, such as silicon dioxide or aluminum oxide. The thickness of the transparent transition material layer 231a can be as thin as possible. The transparent transition material layer 231a can be deposited using methods such as atomic layer deposition (ALD), chemical vapor deposition (CVD), evaporation, or sputtering, as shown in Figure 10.

[0168] Etching is performed on the transparent transition material layer 231a at the position corresponding to each first grid hole to form vias, thus obtaining the transparent transition layer 231. The diameter of the vias is no greater than 0.5 μm. The methods for forming the vias can be, but are not limited to, high-precision photolithography, photoresist reflow, pattern step transfer, etc., as shown in Figure 11.

[0169] The filler 233 at the corresponding first grid hole of each LED mesa and transparent transition layer 231 is removed through vias. The method for removing the filler 233 can be: applying O2 plasma non-directionally, isotropically drying the filler 233 to form a cavity region, as shown in Figure 12.

[0170] A transmission-reflection layer 232 is formed on the transparent transition layer 231. The transmission-reflection layer 232 can be deposited by reactive ion deposition, evaporation, sputtering, or other methods. The transmission-reflection layer 232 can be a distributed Bragg reflector layer, as shown in Figure 13.

[0171] In some embodiments of this disclosure, the step of etching the transparent transition material layer 231a to form vias corresponding to the positions of each first grid hole may include: depositing a mask on the transparent transition material layer 231a and spin-coating photoresist; exposing and developing the mask using a photolithography machine to obtain a mask pattern; dry etching the mask to form openings corresponding to each first grid hole; reactive ion etching the transparent transition material layer 231a to form vias; and removing the photoresist and mask.

[0172] Figures 14 to 16 show schematic diagrams of the structure forming the light conversion structure. In some embodiments of this disclosure, referring to Figures 14 to 16, the fabrication method further includes: forming the light conversion structure 3. Forming the light conversion structure 3 includes: forming a second fence structure 31 on the optical layer 23; wherein the second fence structure 31 has a plurality of second grid holes, each corresponding to a plurality of first grid holes; and forming a plurality of light conversion units 32 in the plurality of second grid holes.

[0173] A second fence structure 31 can be formed on the optical layer 23, as shown in Figure 14.

[0174] In some embodiments of this disclosure, forming a second grid structure 31 on the optical layer 23 includes: forming a second light-blocking substrate material layer on the optical layer 23; etching the second light-blocking substrate material layer to form a plurality of second grid holes corresponding one-to-one with the first grid holes, thereby obtaining a second light-blocking substrate 311; forming a second reflective material layer on the optical layer 23 and the second light-blocking substrate 311; and etching the second reflective material layer to form a second reflective layer 312 at least on the sidewalls of the second grid holes.

[0175] It should be noted that the method for forming the second light-blocking substrate material layer is similar to the method for forming the first light-blocking substrate material layer 221a, the method for forming the second light-emitting substrate is similar to the method for forming the first light-blocking substrate 221, the method for forming the second reflective material layer is similar to the method for forming the first reflective material layer 222a, and the method for forming the second reflective layer 312 is similar to the method for forming the first reflective layer 222. Please refer to the method for forming the first fence structure 22 described above; it will not be repeated here.

[0176] Multiple light conversion units 32 are formed in multiple second grid apertures, as shown in Figures 15 and 16.

[0177] In some embodiments of this disclosure, a plurality of light conversion units 32 are formed in a plurality of second grid holes, including: filling the plurality of second grid holes with a light conversion material; wherein the light conversion material includes at least: a first light conversion material, a second light conversion material, and a transparent material; filling a portion of the second grid holes with the first light conversion material to form a first light conversion unit 321 to convert light passing through the optical layer 23 into a first color light; filling a portion of the second grid holes with the second light conversion material to form a second light conversion unit 322 to convert light passing through the optical layer 23 into a second color light; and filling a portion of the second grid holes with the transparent material to form a transparent unit 324 to transmit light passing through the optical layer 23.

[0178] When the LED unit 21 emits blue light, as shown in Figure 15, a first light conversion material can be formed in the second grid holes. The first light conversion material can be filled by spin coating and drying.

[0179] The area where the first light conversion unit 321 needs to be formed is illuminated by light. The area where the first light conversion unit 321 needs to be formed can be exposed by blocking other areas with a mask layer.

[0180] The mask layer is removed, and the first light conversion material is developed using a developing solution. Since only the area of ​​the first light conversion unit 321 is photocured, the remaining portion is removed under the action of the developing solution, thereby forming the first light conversion unit 321 in a portion of the second grid aperture, converting the blue light emitted by the corresponding LED unit into red light.

[0181] A second light conversion unit 322 can also be formed within the second grid holes in other parts of the second grid structure 31 to convert the blue light emitted by the corresponding LED unit into green light; a transparent unit 324 can be formed within the second grid holes in other parts of the second grid structure 31 to directly transmit the blue light emitted by the corresponding LED unit. That is, different light conversion units 32 are formed within different second grid holes. This realizes a full-color Micro LED microdisplay chip.

[0182] In some embodiments of this disclosure, a plurality of light conversion units 32 are formed in a plurality of second grid holes, including: filling the plurality of second grid holes with a light conversion material; wherein the light conversion material includes at least: a first light conversion material, a second light conversion material, and a third light conversion material; filling a portion of the second grid holes with the first light conversion material to form a first light conversion unit 321 to convert light passing through the optical layer 23 into a first color light; filling a portion of the second grid holes with the second light conversion material to form a second light conversion unit 322 to convert light passing through the optical layer 23 into a second color light; and filling a portion of the second grid holes with the third light conversion material to form a third light conversion unit 323 to convert light passing through the optical layer 23 into a third color light.

[0183] When LED unit 21 does not emit blue light, as shown in Figure 16, a first light conversion material can be formed in the second grid holes. The first light conversion material can be filled by spin coating and drying.

[0184] The area where the first light conversion unit 321 needs to be formed is illuminated by light. The area where the first light conversion unit 321 needs to be formed can be exposed by blocking other areas with a mask layer.

[0185] The mask layer is removed, and the first light conversion material is developed using a developing solution. Since only the area of ​​the first light conversion unit 321 is photocured, the remaining portion is removed under the action of the developing solution, thereby forming the first light conversion unit 321 in a portion of the second grid aperture, converting the blue light emitted by the corresponding LED unit into red light.

[0186] A second light conversion unit 322 can also be formed within the second grid holes in other parts of the second grid structure 31 to convert the blue light emitted by the corresponding LED unit into green light; a third light conversion unit 323 can be formed within the second grid holes in other parts of the second grid structure 31 to convert the blue light emitted by the corresponding LED unit into blue light. That is, different light conversion units 32 are formed within different second grid holes. This realizes a full-color Micro LED microdisplay chip.

[0187] The preparation method proposed in this disclosure involves planarizing the filler and then depositing a transparent transition material layer. Vias are etched at the positions of each first grid hole in the transparent transition material layer. After the filler is drained through the vias, a transmission and reflection layer is deposited to seal the cavity region.

[0188] The fabrication method proposed in this disclosure only requires that the vias correspond to the positions of the first grid holes, so the positional accuracy requirements for etching the vias are not high.

[0189] The preparation method proposed in this disclosure can achieve the sealing of the cavity region by simply depositing a transmission and reflection layer after the filler is dried through the pores, without requiring precise alignment or complex filling.

[0190] Compared to existing technologies, such as Chinese patent documents CN119050126A or CN119050236A, the preparation method proposed in this disclosure can seal the cavity region through a simple process, thereby limiting the heat transfer of the LED unit to the light conversion structure. This not only improves the lifespan of the microdisplay chip but also reduces manufacturing costs, increases product yield, and is suitable for mass production.

[0191] The above description is merely a specific embodiment of this disclosure. Under the teachings of this disclosure, those skilled in the art can make other improvements or modifications based on the above embodiments. Those skilled in the art should understand that the above specific description is only to better explain the purpose of this disclosure, and the scope of protection of this disclosure should be determined by the scope of the claims.

[0192] Furthermore, those skilled in the art will understand that although some embodiments described herein include certain features included in other embodiments but not others, combinations of features from different embodiments are intended to be within the scope of this disclosure and form different embodiments. For example, in the following claims, any of the claimed embodiments can be used in any combination.

Claims

1. A Micro LED microdisplay chip, wherein, The microdisplay chip includes: a driving substrate and a light-emitting structure disposed on the driving substrate; The light-emitting structure includes: multiple LED units, a first fence structure, and an optical layer; Multiple LED units are arranged at intervals on the driving substrate, and each LED unit can be driven individually by the driving substrate. The multiple LED units have multiple corresponding LED platforms. The first fence structure has a plurality of first grid holes, which respectively surround a plurality of LED platforms, and the first fence structure is higher than a plurality of LED units; The optical layer is disposed on the first grid structure, and the LED platform and the optical layer form a cavity area at the corresponding first grid hole.

2. The Micro LED microdisplay chip according to claim 1, wherein, The first fence structure includes: a first light-blocking substrate and a first reflective layer disposed on the surface of the first light-blocking substrate; The first light-blocking substrate has a plurality of the first grid holes; The first reflective layer is disposed at least on the sidewall of the first grid hole.

3. The Micro LED microdisplay chip according to claim 1, wherein, The optical layer includes: a transparent transition layer disposed on the first fence structure and a transmission and reflection layer disposed on the transparent transition layer; The optical layer is used to transmit light from the plurality of LED units.

4. The Micro LED microdisplay chip according to claim 3, wherein, The transparent transition layer has vias at the positions corresponding to each of the first grid holes.

5. The Micro LED microdisplay chip according to claim 3, wherein, The transmission and reflection layer is a distributed Bragg reflector layer.

6. The Micro LED microdisplay chip according to claim 3, wherein, The transparent transition layer is made of a transparent inorganic oxide.

7. The Micro LED microdisplay chip according to claim 4, wherein, The diameter of the via is less than 0.5 μm.

8. The Micro LED microdisplay chip according to claim 1, wherein, The microdisplay chip further includes: a light conversion structure disposed on the optical layer; The light conversion structure includes a second fence structure and multiple light conversion units. The second fence structure has a plurality of second grid holes, and the plurality of second grid holes correspond one-to-one with the plurality of first grid holes; The plurality of light conversion units are respectively disposed in the plurality of second grid holes.

9. The Micro LED microdisplay chip according to claim 8, wherein, The second fence structure includes: a second light-blocking substrate and a second reflective layer disposed on the surface of the second light-blocking substrate; The second light-blocking substrate has a plurality of the second grid holes; The second reflective layer is disposed at least on the sidewall of the second grid hole.

10. The Micro LED microdisplay chip according to claim 8, wherein, The plurality of optical conversion units include at least: a first optical conversion unit and a second optical conversion unit; The first light conversion unit converts the light passing through the optical layer into light of the first color; The second light conversion unit converts the light passing through the optical layer into light of a second color.

11. The Micro LED microdisplay chip according to claim 10, wherein, The plurality of light conversion units further include: a transparent unit; The transparent unit transmits light that has passed through the optical layer.

12. The Micro LED microdisplay chip according to claim 10, wherein, The plurality of optical conversion units further include: a third optical conversion unit; The third light conversion unit converts the light passing through the optical layer into a third color light.

13. A method for fabricating a Micro LED microdisplay chip, wherein, The preparation method includes the following steps: A driving substrate is provided, and a light-emitting structure is formed on the driving substrate; The formation of the light-emitting structure on the driving substrate includes: Multiple LED units are formed; wherein, the multiple LED units are arranged at intervals on the driving substrate, and each LED unit can be driven individually by the driving substrate, and the multiple LED units have multiple corresponding LED platforms; A first fence structure is formed; wherein the first fence structure has a plurality of first grid holes, the plurality of first grid holes respectively surround the plurality of LED platforms, and the first fence structure is higher than the plurality of LED units; An optical layer is formed; wherein the optical layer is formed on the first grid structure, and the LED platform and the optical layer form a cavity region at the corresponding first grid hole; The formation of the optical layer includes: The first fence structure is flattened using filler material; A transparent transition material layer is formed on the flattened first fence structure; The transparent transition material layer is etched at the position corresponding to each of the first grid holes to form vias, thus obtaining the transparent transition layer; The filler at the corresponding first grid hole of each LED platform and the transparent transition layer is removed through the via; A transmission and reflection layer is formed on the transparent transition layer.

14. The method for fabricating a Micro LED microdisplay chip according to claim 13, wherein, The formation of the first fence structure includes: A first light-blocking substrate material layer is formed on the plurality of LED units; The first light-blocking substrate material layer is etched to form a plurality of first grid holes surrounding the plurality of LED platforms, thereby obtaining the first light-blocking substrate; A first reflective material layer is formed on the plurality of LED surfaces and the first light-blocking substrate; The first reflective material layer is etched to form a first reflective layer at least on the sidewall of the first grid hole.

15. The method for fabricating a Micro LED microdisplay chip according to claim 13, wherein, The preparation method further includes: Forming a light conversion structure; The light conversion structure includes: A second fence structure is formed on the optical layer; wherein the second fence structure has a plurality of second grid holes, and the plurality of second grid holes correspond one-to-one with the plurality of first grid holes; Multiple light conversion units are formed in multiple second grid apertures.

16. The method for fabricating a Micro LED microdisplay chip according to claim 15, wherein, The formation of the second fence structure on the optical layer includes: A second light-blocking substrate material layer is formed on the optical layer; The second light-blocking substrate material layer is etched to form a plurality of second grid holes that correspond one-to-one with the first grid holes, thereby obtaining the second light-blocking substrate; A second reflective material layer is formed on the optical layer and the second light-blocking substrate; The second reflective material layer is etched to form a second reflective layer at least on the sidewall of the second grid hole.

17. The method for fabricating a Micro LED microdisplay chip according to claim 15, wherein, The process of forming multiple light conversion units in multiple second grid apertures includes: A light conversion material is filled within a plurality of second grid apertures; wherein the light conversion material comprises at least: a first light conversion material and a second light conversion material; A first light conversion unit is formed by filling a portion of the second grid aperture with the first light conversion material to convert light passing through the optical layer into light of a first color. A second light conversion unit is formed by filling a portion of the second grid aperture with the second light conversion material to convert light passing through the optical layer into second color light.

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