Micro-display module and preparation method thereof

Abstract

The invention discloses a micro display module and a preparation method thereof, and relates to the technical field of display. The at least two stacked pixel layers are bonded on the same side of the driving substrate, and a flat interface is arranged between every two adjacent pixel layers; each pixel layer comprises a micro LED array and a passivation layer located between micro LEDs, and the micro LEDs are electrically connected with the driving substrate; wherein the surface of the side, away from the driving substrate, of the pixel layer farthest from the driving substrate comprises a plurality of grooves, and color conversion layers used for converting part of light emitted by the micro LEDs into red light are arranged in the grooves. According to the technical scheme provided by the invention, the production yield of the micro display module is improved, and the problems that the preparation difficulty of a red micro LED is large and the external quantum efficiency is low are solved.

Description

Technical Field

[0001] The embodiments of the present invention relate to the field of display technology, and in particular to a micro display module and a preparation method thereof. Background Art

[0002] Micro-LED (Micro Light Emitting Diode Display) display technology has the advantages of self-luminescence of pixels. Compared with LCD (Liquid Crystal Display) display technology and OLED (Organic Light Emitting Display) display technology, Micro-LED display technology has the advantages of high contrast, fast response speed, wide color gamut, low power consumption, and strong energy saving. It is called the "next generation display technology" and is currently mainly used in large-screen displays, wearable electronics, car displays, AR / VR and other display fields. At the same time, its applications also cover biology, medicine, optical communications and other fields.

[0003] However, for micro-display modules, the integration of thousands or even millions of micro-LEDs with pixel driver circuit arrays is very challenging. Currently, full-color display can be achieved through stacked Micro-LEDs; the common preparation method in the industry is to grow monochrome epitaxial wafers separately, and then cut them into separate RGB (red, green, and blue) light-emitting chips after chip processing, and then use mass transfer technology to splice and weld the chips on the drive substrate to achieve RGB full-color display, but the mass transfer yield is low, and any single defect needs to be repaired, which will also consume a lot of time. Secondly, due to the limitations of the epitaxial structure and the small size effect, the preparation of red Micro-LEDs is difficult and the external quantum efficiency is very low, which makes it difficult to meet the requirements of high-performance full-color displays. Summary of the invention

[0004] The embodiment of the present invention provides a micro display module and a preparation method thereof, so as to improve the production yield of the micro display module and improve the problem that the preparation of red micro LEDs is difficult and the external quantum efficiency is low.

[0005] According to one aspect of the present invention, there is provided a micro display module, comprising:

[0006] Driver substrate;

[0007] At least two stacked pixel layers are hybrid-bonded on the same side of the driving substrate, and have a flat interface between adjacent pixel layers; each of the pixel layers comprises a micro-LED array and a passivation layer between the micro-LEDs, and the micro-LEDs are electrically connected to the driving substrate;

[0008] The surface of the pixel layer farthest from the driving substrate on the side away from the driving substrate comprises a plurality of grooves, and a color conversion layer for converting part of the light emitted by the micro LEDs into red light is arranged in the grooves.

[0009] Optionally, the bottom surface of the groove is curved, and the curved surface is convex toward the color conversion layer;

[0010] And / or, the thickness of the color conversion layer is equal to the depth of the groove.

[0011] Optionally, each of the micro LEDs comprises:

[0012] A first semiconductor layer, located on one side of the driving substrate;

[0013] A quantum well layer, located on a side of the first semiconductor layer away from the driving substrate;

[0014] A second semiconductor layer is located on a side of the quantum well layer away from the driving substrate;

[0015] Wherein, at least the second semiconductor layer in the pixel layer farthest from the driving substrate is a continuous film layer, and the groove is located on a side of the second semiconductor layer in the pixel layer farthest from the driving substrate away from the driving substrate.

[0016] Optionally, a vertical projection of each of the color conversion layers on the driving substrate at least partially overlaps with a vertical projection of a micro LED in a pixel layer farthest from the driving substrate on the driving substrate;

[0017] The light emitted by the micro LED in the pixel layer farthest from the driving substrate is blue light.

[0018] Optionally, the number of pixel layers is two, which are a first pixel layer and a second pixel layer which are successively away from the driving substrate;

[0019] The first pixel layer includes a plurality of green micro LEDs emitting green light, and the second pixel layer includes a plurality of blue micro LEDs emitting blue light; wherein the number of the blue micro LEDs is greater than or equal to the number of the green micro LEDs.

[0020] Optionally, one of the blue micro LEDs is disposed above two opposite sides of each of the green micro LEDs, and a vertical projection of the color conversion layer on the driving substrate at least partially overlaps with a vertical projection of one of the blue micro LEDs on the driving substrate;

[0021] Wherein, the vertical projections of the two blue micro LEDs located above the green micro LED on the driving substrate do not overlap with the vertical projection of the green micro LED on the driving substrate;

[0022] Alternatively, a vertical projection of at least one of the two blue micro LEDs located above the green micro LED on the driving substrate at least partially overlaps with a vertical projection of the green micro LED on the driving substrate.

[0023] Optionally, the second pixel layer includes a plurality of annular blue micro LEDs, and a vertical projection of each of the annular blue micro LEDs on the driving substrate corresponds to and surrounds a vertical projection of a green micro LED on the driving substrate; the vertical projection of the color conversion layer on the driving substrate is located on one side of the vertical projection of the green micro LED on the driving substrate, and partially overlaps with the vertical projection of the annular blue micro LED on the driving substrate;

[0024] Alternatively, the second pixel layer includes a plurality of annular blue micro LEDs and a plurality of central blue micro LEDs, each of the central blue micro LEDs being surrounded by a corresponding annular blue micro LED; a vertical projection of the central blue micro LED on the driving substrate at least partially overlaps with a vertical projection of the green micro LED on the driving substrate; wherein a vertical projection of the color conversion layer on the driving substrate at least partially overlaps with a vertical projection of the central blue micro LED on the driving substrate, or a vertical projection of the color conversion layer on the driving substrate partially overlaps with a vertical projection of the annular blue micro LED on the driving substrate.

[0025] Optionally, the surface of the driving substrate includes a plurality of first driving electrodes and a common driving electrode;

[0026] Each of the micro LEDs is electrically connected to a corresponding first driving electrode through a first electrode connector, and each of the micro LEDs is also electrically connected to the common driving electrode through a common electrode connector;

[0027] Among them, at least the second semiconductor layer in the pixel layer farthest from the driving substrate contacts the common electrode connector; the first electrode connector is composed of at least one of a conductive column and a conductive layer; the common electrode connector is composed of at least one of a conductive column and a conductive layer.

[0028] According to another aspect of the present invention, there is provided a method for preparing a micro display module, comprising:

[0029] Providing a drive substrate;

[0030] At least two pixel layers are formed on the same side of the driving substrate, with a flat interface between adjacent pixel layers; each of the pixel layers comprises a micro-LED array and a passivation layer between the micro-LEDs, and the micro-LEDs are electrically connected to the driving substrate;

[0031] A plurality of grooves are formed on a surface of a pixel layer farthest from the driving substrate and away from the driving substrate, and a color conversion layer is formed in the grooves. The color conversion layer is used to convert light emitted by part of the micro LEDs into red light.

[0032] Optionally, forming at least two pixel layers on the same side of the driving substrate includes:

[0033] Forming a first epitaxial structure on a first substrate, patterning the first epitaxial structure to form a plurality of green micro LEDs, forming a first passivation layer between adjacent green micro LEDs and on a side of the green micro LEDs away from the first substrate, and polishing the surface of the first passivation layer until the green micro LEDs are exposed to form a first pixel layer;

[0034] forming a first wiring layer on a surface of the first pixel layer away from the first substrate, bonding the first pixel layer with the first wiring layer facing the drive substrate, removing the first substrate, and forming a second wiring layer on the exposed surface of the first pixel layer;

[0035] forming a second epitaxial structure on a second substrate, patterning the second epitaxial structure to form a plurality of blue micro LEDs, forming a second passivation layer between adjacent blue micro LEDs and on a side of the blue micro LEDs away from the second substrate, and flattening a surface of the second passivation layer until the blue micro LEDs are exposed, thereby forming a second pixel layer;

[0036] forming a third wiring layer on a surface of the second pixel layer away from the second substrate, bonding the second pixel layer with the third wiring layer on a side facing the drive substrate to the second wiring layer, and removing the second substrate;

[0037] The forming of a plurality of grooves on a surface of a pixel layer farthest from the driving substrate and away from the driving substrate comprises:

[0038] A plurality of grooves having a curved bottom are formed on a surface of the second semiconductor layer at a side away from the driving substrate in the second pixel layer, and the curved bottom is convex toward the color conversion layer.

[0039] The embodiment of the present invention provides a micro display module and a preparation method thereof, wherein the micro display module comprises: a driving substrate; at least two stacked pixel layers, bonded on the same side of the driving substrate, and having a flat interface between adjacent pixel layers; each pixel layer comprises a micro LED array and a passivation layer located between the micro LEDs; each micro LED array is electrically connected to the driving substrate, and the micro LEDs located in the same pixel layer have the same luminous color; wherein the surface of the pixel layer farthest from the driving substrate on the side away from the driving substrate comprises a plurality of grooves, and a color conversion layer for converting part of the light emitted by the micro LEDs into red light is arranged in the grooves. The technical solution provided by the embodiment of the present invention bonds at least two pixel layers on the same side of the driving substrate, and by arranging a plurality of grooves on the surface of the pixel layer farthest from the driving substrate on the side away from the driving substrate, and arranging a color conversion layer for converting part of the light emitted by the micro LEDs into red light in the grooves, it is possible to avoid the need to prepare a red micro LED epitaxial structure, thereby reducing the process complexity, improving the mass production yield, and improving the problem of difficulty in preparing red micro LEDs and low external quantum efficiency.

[0040] It should be understood that the contents described in this section are not intended to identify the key or important features of the embodiments of the present invention, nor are they intended to limit the scope of the present invention. Other features of the present invention will become easily understood through the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0041] In order to more clearly illustrate the technical solutions in the embodiments of the present invention, the following briefly introduces the drawings required for use in the description of the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without creative work.

[0042] Figure 1 is a structural cross-sectional view of a micro display module provided by an embodiment of the present invention;

[0043] Figure 2 is a structural cross-sectional view of another micro display module provided by an embodiment of the present invention;

[0044] Figure 3 is a structural cross-sectional view of another micro display module provided by an embodiment of the present invention;

[0045] Figure 4 is a schematic diagram of an arrangement of adjacent blue micro LEDs, green micro LEDs and a color conversion layer provided by an embodiment of the present invention;

[0046] Figure 5 is a schematic diagram of another arrangement of adjacent blue micro LEDs, green micro LEDs and a color conversion layer provided by an embodiment of the present invention;

[0047] Figure 6 is a schematic diagram of another arrangement of adjacent blue micro LEDs, green micro LEDs and a color conversion layer provided by an embodiment of the present invention;

[0048] Figure 7 is a flow chart of a method for preparing a micro display module provided by an embodiment of the present invention;

[0049] Figure 8 It is a schematic cross-sectional structure diagram after a driving electrode and a first dielectric layer are formed on the surface of a driving substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0050] Fig. 9 It is a schematic diagram of the cross-sectional structure after forming a second dielectric layer on the surface of a first dielectric layer and forming a conductive column in the second dielectric layer in a method for preparing a micro display module provided by an embodiment of the present invention;

[0051] Fig.10 It is a schematic cross-sectional structure diagram after a first epitaxial structure is formed on a first substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0052] Fig.11 It is a schematic diagram of a cross-sectional structure after a current spreading layer is formed on a first epitaxial structure in a method for preparing a micro display module provided by an embodiment of the present invention;

[0053] Fig.12 It is a schematic cross-sectional structure diagram of a method for preparing a micro display module provided by an embodiment of the present invention, in which a first passivation layer is formed between adjacent green micro LEDs and on a side of the green micro LED away from a first substrate and the first passivation layer is flat-polished;

[0054] Fig.13 It is a schematic cross-sectional structure diagram after a first wiring layer is formed on a surface of a first pixel layer away from a first substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0055] Fig.14 It is a schematic cross-sectional structure diagram of a method for preparing a micro display module provided by an embodiment of the present invention, in which a side of a first pixel layer having a first wiring layer faces a driving substrate and is hybrid-bonded with a wiring layer on a surface of the driving substrate;

[0056] Fig.15 It is a schematic diagram of the cross-sectional structure after removing the first substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0057] Fig.16It is a schematic cross-sectional structure diagram after a second wiring layer is formed on the surface of a first pixel layer in a method for preparing a micro display module provided by an embodiment of the present invention;

[0058] Fig.17 It is a schematic cross-sectional structure diagram after a second epitaxial structure is formed on a second substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0059] Fig.18 It is a schematic cross-sectional structure diagram after a third wiring layer is formed on a surface of a second pixel layer away from a second substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0060] Fig.19 It is a schematic cross-sectional structure diagram of bonding the second pixel layer with the third wiring layer facing the driving substrate to the second wiring layer in a method for preparing a micro display module provided by an embodiment of the present invention;

[0061] Fig. 20 It is a schematic diagram of the cross-sectional structure after removing the second substrate in a method for preparing a micro display module provided by an embodiment of the present invention;

[0062] Fig.21 It is a schematic cross-sectional structure diagram after a plurality of grooves with curved bottom surfaces are formed on a surface of a second semiconductor layer in a second pixel layer away from a driving substrate in a method for preparing a micro display module provided by an embodiment of the present invention. DETAILED DESCRIPTION

[0063] In order to enable those skilled in the art to better understand the scheme of the present invention, the technical scheme in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0064] It should be noted that the terms "first", "second", etc. in the specification and claims of the present invention and the above-mentioned drawings are used to distinguish similar objects, and are not necessarily used to describe a specific order or sequence. It should be understood that the data used in this way can be interchanged where appropriate, so that the embodiments of the present invention described herein can be implemented in an order other than those illustrated or described herein. In addition, the terms "including" and "having" and any variations thereof are intended to cover non-exclusive inclusions, for example, a process, method, system, product or device that includes a series of steps or units is not necessarily limited to those steps or units that are clearly listed, but may include other steps or units that are not clearly listed or inherent to these processes, methods, products or devices.

[0065] An embodiment of the present invention provides a micro display module. Figure 1 is a structural cross-sectional view of a micro display module provided by an embodiment of the present invention, with reference to Figure 1 , the micro display module includes:

[0066] A driving substrate 300;

[0067] At least two stacked pixel layers are bonded on the same side of the driving substrate 300, and there is a flat interface between adjacent pixel layers; each pixel layer includes a micro LED array and a passivation layer located between the micro LEDs 50, each micro LED 50 is electrically connected to the driving substrate 300, and the micro LEDs 50 located in the same pixel layer emit the same color;

[0068] The surface of the pixel layer farthest from the driving substrate 300 on the side facing away from the driving substrate 300 includes a plurality of grooves, in which a color conversion layer 60 for converting part of the light emitted by the micro LED 50 into red light is arranged.

[0069] Specifically, the micro display module includes a driving substrate 300 and at least two pixel layers, and the at least two pixel layers are sequentially away from the driving substrate 300. Each pixel layer includes a plurality of micro LEDs 50, and the plurality of micro LEDs 50 are arranged in an array. The pixel layer also includes a passivation layer located between the micro LEDs 50, and the passivation layer is arranged between the micro LEDs 50 to fill the gaps between the micro LEDs 50, so that the interface between the adjacent layers is flat, so as to facilitate bonding with the next pixel layer. Figure 1 Two pixel layers are shown by way of example, namely a first pixel layer 100 and a second pixel layer 200. The first pixel layer 100 includes a plurality of green micro LEDs 50G and a first passivation layer 101 located between the green micro LEDs 50G, and the second pixel layer 200 includes a plurality of blue micro LEDs 50B and a second passivation layer 201 located between the blue micro LEDs 50B.

[0070] The material of the passivation layer can be silicon dioxide, resin, etc., which is both non-conductive and transparent. This provides electrical isolation between the micro LEDs 50 and the electrode connectors, but also allows the light generated by the micro LEDs 50 in the lower layer to propagate through the layer. Another example of a material for the passivation layer is silicon nitride. The passivation layer for each pixel layer does not have to be a single homogeneous material, and a combination of materials or structures can also be used. Regardless of the detailed structure, preferably, each pixel layer is transparent in the area laterally located above the lower micro LEDs 50, so that the light generated by the lower micro LEDs 50 can propagate through such an area.

[0071] Each micro LED 50 can be electrically connected to the driving substrate 300 through an electrode connector, and the micro LEDs 50 located in the same pixel layer have the same luminous color. The driving substrate 300 is used to provide a driving signal to the micro LED 50 to drive the micro LED 50 to emit light. The driving substrate 300 is usually a printed circuit board with a CMOS driving circuit configured on the surface, and the circuit configured on the surface is designed according to specific application requirements. By hybrid bonding at least two pixel layers on the same side of the driving substrate 300, a whole layer of pixel layers can be synchronously transferred to the driving substrate 300 and electrically connected to the driving substrate 300, instead of splicing and welding a single light-emitting chip on the driving substrate 300 through mass transfer technology in related technologies, which can reduce process complexity and improve mass production yield.

[0072] Among them, the surface of the pixel layer farthest from the driving substrate 300 on the side away from the driving substrate 300 includes a plurality of grooves, and a color conversion layer 60 for converting the light emitted by part of the micro LED 50 into red light is arranged in the groove. It can be understood that part of the micro LED 50 is used as an excitation pixel 501, and the light emitted by the excitation pixel 501 excites the color conversion layer 60 to emit red light, so that the combination of the excitation pixel 501 and the color conversion layer 60 can replace the micro LED 50 that directly emits red light. Therefore, there is no need to prepare a red micro LED epitaxial structure, thereby reducing the process complexity, improving the mass production yield, and improving the problem of high difficulty in preparing red micro LEDs and low external quantum efficiency. It should be noted that the light emission wavelength of the excitation pixel 501 is shorter than the wavelength of red light, so that the color conversion layer 60 is excited by light with a shorter wavelength to undergo color conversion and emit red light. The color conversion layer 60 can be made of quantum dot material or red phosphor. The excitation pixels 501 corresponding to different color conversion layers 60 can be located in the same pixel layer or in different pixel layers.

[0073] In addition, by placing the color conversion layer 60 in the groove, the color conversion layer 60 and the excitation pixel 501 can be precisely aligned through the groove, and the depth and shape of the groove can be controlled to facilitate precise control of the thickness and shape of the color conversion layer 60. The method of forming the groove includes but is not limited to dry etching, ion beam etching, laser etching, nanoimprinting and the like.

[0074] The micro display module provided by the embodiment of the present invention bonds at least two pixel layers to the same side of the driving substrate 300, and by arranging a plurality of grooves on the surface of the pixel layer farthest from the driving substrate 300 which is away from the driving substrate 300, and arranging a color conversion layer 60 in the groove for converting part of the light emitted by the micro LED 50 into red light, there is no need to prepare a red micro LED epitaxial structure, thereby reducing the process complexity, improving the mass production yield, and improving the problem of difficulty in preparing red micro LEDs and low external quantum efficiency.

[0075] Based on the above embodiments, optionally, Figure 2 is a structural cross-sectional view of another micro display module provided by an embodiment of the present invention, referring to Figure 2 The bottom surface of the groove is a curved surface, and the curved surface is convex toward the color conversion layer 60 .

[0076] Specifically, the bottom surface of the groove is set to be a curved surface, and the curved surface is convex toward the color conversion layer 60, so that the convex part can be in the shape of a convex lens. The light emitted by the micro LED 50 located below it passes through this part. The convex lens shape can improve the luminous efficiency and light intensity. There is no need to set a separate lens, which simplifies the preparation process of the micro display module, saves the preparation cost, and can also reduce the thickness of the micro display module, which is conducive to application in micro display devices; at the same time, compared with the planar bottom surface of the groove, the curved bottom surface of the groove increases the area of ​​the bottom surface of the groove, so that the contact area between the color conversion layer 60 and the bottom surface of the groove is larger, which improves the excitation efficiency of the color conversion layer 60 and makes the color conversion layer 60 more stably and reliably arranged in the groove.

[0077] Furthermore, the thickness of the color conversion layer 60 is equal to the depth of the groove. The thickness of the color conversion layer 60 is set to be equal to the depth of the groove, so that the color conversion layer 60 can fill the groove, ensuring that the surface of the pixel layer farthest from the driving substrate 300 away from the driving substrate 300 is flat, so as to facilitate the subsequent preparation process. In other embodiments, the thickness of the color conversion layer 60 can also be greater than or less than the depth of the groove.

[0078] Based on the above embodiments, please refer to Figure 1 and Figure 2 Optionally, each micro-LED 50 includes:

[0079] A first semiconductor layer, located on one side of the driving substrate 300;

[0080] The quantum well layer is located on a side of the first semiconductor layer away from the driving substrate 300;

[0081] The second semiconductor layer 20' is located on a side of the quantum well layer away from the driving substrate 300;

[0082] At least the second semiconductor layer 20 ′ in the pixel layer farthest from the driving substrate 300 is a continuous film layer, and the groove is located on the side of the second semiconductor layer 20 ′ in the pixel layer farthest from the driving substrate 300 away from the driving substrate 300 .

[0083] Specifically, the micro LED 50 includes a first semiconductor layer, a quantum well layer, and a second semiconductor layer 20' which are stacked in sequence in a direction perpendicular to the driving substrate 300. The first semiconductor layer, the quantum well layer, and the second semiconductor layer 20' are respectively an N-type semiconductor layer, a quantum well layer, and a P-type semiconductor layer, or a P-type semiconductor layer, a quantum well layer, and an N-type semiconductor layer. The N-type semiconductor layer is used to provide electrons, and the P-type semiconductor layer is used to provide holes. Electrons and holes recombine in the quantum well layer to release photons. This synergistic effect enables the micro LED 50 to emit light efficiently.

[0084] During the preparation of the pixel layer, an epitaxial structure can be formed on the substrate. The epitaxial structure can include a second semiconductor epitaxial layer, a quantum well epitaxial layer, and a first semiconductor epitaxial layer sequentially formed on one side of the substrate; the epitaxial structure is patterned by an etching process to form a plurality of micro LEDs 50. The size, shape, and array arrangement of the micro LEDs 50 can be adjusted by controlling the patterning; a passivation layer is then formed between adjacent micro LEDs 50 and on the side of the micro LEDs 50 away from the substrate by a deposition process, and the surface of the passivation layer is polished to expose the micro LEDs 50, thereby forming a pixel layer on the substrate. After the pixel layer is bonded to one side of the drive substrate 300, the substrate is removed.

[0085] The substrate may be a Si substrate or a sapphire substrate, or a substrate of other materials. The material of the N-type semiconductor layer may be an N-type GaN material; the material of the P-type semiconductor layer may be a P-type GaN material. The material of the quantum well layer 30 may be determined according to the luminescent color. For example, the material combination of the blue quantum well layer for emitting blue light may include gallium nitride (GaN) and indium gallium nitride (InGaN). By adjusting the proportion of the materials and the thickness of the quantum well, efficient blue luminescence may be achieved. The material combination of the green quantum well layer for emitting green light may include gallium nitride (GaN) and indium gallium nitride (InGaN). By adjusting the proportion of the materials and the thickness of the quantum well, efficient green luminescence may be achieved.

[0086] When the first semiconductor layer, the quantum well layer, and the second semiconductor layer 20' are respectively a P-type semiconductor layer, a quantum well layer 30, and an N-type semiconductor layer, after forming the first semiconductor epitaxial layer, a current spreading layer 40 may be formed on the surface of the first semiconductor epitaxial layer away from the substrate to facilitate the spreading of current on the surface of the first semiconductor layer. The material of the current spreading layer 40 may be indium tin oxide (ITO) having light transmittance.

[0087] In the process of patterning the epitaxial structure by etching, the second semiconductor epitaxial layer, the quantum well epitaxial layer and the first semiconductor epitaxial layer can be etched in sequence until the surface of the substrate is etched, so that each micro LED 50 is independently set, reducing the interference of electrical signals between the micro LEDs 50. The second semiconductor epitaxial layer and the quantum well epitaxial layer can also be etched in sequence until the surface of the second semiconductor epitaxial layer is exposed, or the second semiconductor epitaxial layer is partially etched, so that the second semiconductor layers 20' of each micro LED 50 in the pixel layer are connected together and are still a continuous film layer, which can reduce the depth of etching the epitaxial structure and reduce the difficulty of etching. In the embodiment of the present invention, at least the second semiconductor layer 20' in the pixel layer farthest from the driving substrate 300 is a continuous film layer, so that the groove for placing the color conversion layer 60 can be formed on the surface of the second semiconductor layer 20' away from the driving substrate 300, and there is no need to set a film layer for forming the groove, thereby reducing the preparation cost and thickness of the micro display module.

[0088] Based on the above embodiments, please continue to refer to Figure 1 and Figure 2 Optionally, the vertical projection of the groove for placing the color conversion layer on the driving substrate 300 at least partially overlaps with the micro LED 50 in the pixel layer farthest from the driving substrate 300, so that the color conversion layer 60 converts the light emitted by the micro LED 50 in the pixel layer farthest from the driving substrate 300 into red light, which can reduce the distance between the color conversion layer 60 and the excitation pixel 501, and increase the amount of light emitted by the excitation pixel 501 into the color conversion layer 60. In addition, forming the groove for placing the color conversion layer 60 on the surface of the second semiconductor layer 20' away from the driving substrate 300 can also further reduce the distance between the color conversion layer 60 and the excitation pixel 501, and increase the amount of light emitted by the excitation pixel 501 into the color conversion layer 60.

[0089] Furthermore, Figure 3 is a structural cross-sectional view of another micro display module provided by an embodiment of the present invention, referring to Figure 3 A groove 601 with a curved bottom surface can be provided directly above each micro LED 50, and a color conversion layer 60 for converting light into red light can be provided only in part of the groove 601; the curved surface bulges in a direction away from the driving substrate 300, so that a convex lens-shaped convex portion is provided directly above each micro LED 50. The convex lens shape can also be used to improve the luminous efficiency and intensity of other colors of light, such as the luminous efficiency and intensity of green light and blue light.

[0090] Based on the above embodiments, Figure 1~Figure 3Optionally, the light emitted by the micro LED 50 in the pixel layer farthest from the driving substrate 300 is blue light, that is, blue micro LED 50B. In other embodiments, the color conversion layer 60 may be excited by light of other colors to emit red light.

[0091] Based on the above embodiments, please continue to refer to Figure 1~Figure 3 Optionally, the number of pixel layers is two, namely, a first pixel layer 100 and a second pixel layer 200 which are respectively away from the driving substrate 300 in sequence; the first pixel layer 100 includes a plurality of green micro-LEDs 50G emitting green light, and the second pixel layer 200 includes a plurality of blue micro-LEDs 50B emitting blue light; wherein the number of blue micro-LEDs 50B is greater than or equal to the number of green micro-LEDs 50G. The green micro-LEDs 50G are used as green sub-pixels in the micro-display module. Among the blue micro-LEDs 50B, a part of the blue micro-LEDs 50B are used as excitation pixels 501 that excite the color conversion layer 60 to emit red light, thereby forming red sub-pixels in the micro-display module; a part of the blue micro-LEDs 50B are used as blue sub-pixels in the micro-display module. Setting the laser pixels and the blue sub-pixels in the same pixel layer can reduce the thickness and preparation difficulty of the micro-display module, and can also shorten the optical path of the light in the micro-display module and reduce the loss of light.

[0092] In one embodiment of the present invention, when the number of blue micro LEDs 50B is greater than the number of green micro LEDs 50G, a blue micro LED 50B is disposed above each of the two opposite sides of each green micro LED 50G, and the vertical projection of the color conversion layer 60 on the driving substrate 300 at least partially overlaps with the vertical projection of one of the blue micro LEDs 50B on the driving substrate 300. In the embodiment of the present invention, the shape of the blue micro LED 50B can be circular, square, triangular or other shapes; the shape of the green micro LED 50G can be circular, square, triangular or other shapes.

[0093] Among them, reference Figure 4 , and combined with Figure 1~Figure 3 The vertical projections of the two blue micro LEDs 50B located above the green micro LED 50G on the driving substrate 300 do not overlap with the vertical projection of the green micro LED 50G on the driving substrate 300, so that the green micro LED 50G can have better light extraction efficiency.

[0094] Alternatively, refer to Figure 5 , and combined with Figure 1~Figure 3The vertical projection of at least one of the two blue micro LEDs 50B located above the green micro LED 50G on the driving substrate 300 at least partially overlaps with the vertical projection of the green micro LED 50G on the driving substrate 300, thereby improving the integration of the green micro LED 50G in the first pixel layer 100 and the integration of the blue micro LED 50B in the second pixel layer 200, thereby increasing the number of green micro LEDs 50G and the number of blue micro LEDs 50B, and improving the full-color display effect of the micro display module.

[0095] In another embodiment of the present invention, reference Figure 6 , and combined with Figure 1~Figure 3 In the case where the number of blue micro LEDs 50B is equal to the number of green micro LEDs 50G, the second pixel layer 200 includes a plurality of annular blue micro LEDs 50B, and the vertical projection of each annular blue micro LED 50B on the driving substrate 300 corresponds to the vertical projection of a green micro LED 50G on the driving substrate 300; the vertical projection of the color conversion layer 60 on the driving substrate 300 is located on one side of the vertical projection of the green micro LED 50G on the driving substrate 300, and partially overlaps with the vertical projection of the annular blue micro LED 50B on the driving substrate 300. Therefore, part of the light-emitting area of ​​each blue micro LED 50B is used to excite the color conversion layer 60 to emit red light, and the other part of the light-emitting area is used as a blue sub-pixel that emits blue light.

[0096] In another embodiment of the present invention, when the number of blue micro LEDs 50B is greater than the number of green micro LEDs 50G, the second pixel layer 200 includes a plurality of annular blue micro LEDs 50B, and a plurality of central blue micro LEDs 50B (not shown), and each central blue micro LED 50B is correspondingly surrounded by an annular blue micro LED 50B; the vertical projection of the central blue micro LED 50B on the driving substrate 300 at least partially overlaps with the vertical projection of the green micro LED 50G on the driving substrate 300; wherein the vertical projection of the color conversion layer 60 on the driving substrate 300 at least partially overlaps with the vertical projection of the central blue micro LED 50B on the driving substrate 300, or the vertical projection of the color conversion layer 60 on the driving substrate 300 partially overlaps with the vertical projection of the annular blue micro LED 50B on the driving substrate 300.

[0097] It can be understood that each green micro LED 50G has two corresponding blue micro LEDs 50B above it, and the two blue micro LEDs 50B coincide with the central axis of the green micro LED 50G, one of the blue micro LEDs 50B is located at the center, and the shape can be circular, square, triangular or other shapes with a central axis; the other blue micro LED 50B is located at the edge, and the shape is ring-shaped. The blue light chip at the edge surrounds the blue light chip at the center, which can further improve the full-color display effect of the micro display module.

[0098] The color conversion layer 60 can be located directly above the blue light micro LED 50 at the center, which can ensure that the green light and the red light have a better overlap efficiency and achieve full-color display. Alternatively, the color conversion layer 60 is located above a portion of the blue light chip at the edge. In this case, the green light and the blue light can have a better overlap efficiency and achieve full-color display.

[0099] Based on the above embodiments, Figure 1~Figure 3 Optionally, the surface of the driving substrate 300 includes a plurality of first driving electrodes 03a and common driving electrodes 03b; each micro LED 50 is electrically connected to a corresponding first driving electrode 03a through a first electrode connector 04a, and each micro LED 50 is also electrically connected to a common driving electrode 03b through a common electrode connector 04b; at least the second semiconductor layer 20' in the pixel layer farthest from the driving substrate 300 is in contact with the common electrode connector 04b. The first electrode connector 04a is composed of at least one of a conductive column and a conductive layer; the common electrode connector 04b is composed of at least one of a conductive column and a conductive layer.

[0100] Exemplarily, the first electrode connector 04a and the common electrode connector 04b may be formed by the conductive pillars formed in each pixel layer, the conductive pillars and conductive layers formed in the wiring layers between the pixel layers and between the pixel layers, and the conductive pillars formed in the wiring layer between the bottom pixel layer and the driving substrate 300. The first electrode connector 04a may be extended in a direction perpendicular to the driving substrate 300, or may be staggered in sections at the wiring layer; the common electrode connector 04b may be extended in a direction perpendicular to the driving substrate 300, or may be staggered in sections at the wiring layer. The electrode connectors connecting the micro LED 50 and the driving substrate 300 in the micro display module may be set according to actual conditions. Among them, the surface of the first pixel layer 100 close to the driving substrate 300 includes a first wiring layer RDL1, and the first wiring layer RDL1 is bonded to the wiring layer on the surface of the driving substrate 300; the surface of the first pixel layer 100 away from the driving substrate 300 includes a second wiring layer RDL2, and the surface of the second pixel layer 200 close to the driving substrate 300 includes a third wiring layer RDL3, and the second wiring layer RDL2 and the third wiring layer RDL3 are bonded.

[0101] The embodiment of the present invention also provides a method for preparing a micro display module, which is used to prepare the micro display module described in any embodiment of the present invention. Figure 7 is a flow chart of a method for preparing a micro display module provided by an embodiment of the present invention, with reference to Figure 7 , the preparation method of the micro display module includes:

[0102] S10, providing a driving substrate.

[0103] S20, forming at least two pixel layers on the same side of the driving substrate, with a flat interface between adjacent pixel layers; each pixel layer includes a micro LED array, and each micro LED array is electrically connected to the driving substrate.

[0104] S30, forming a plurality of grooves on a surface of a pixel layer farthest from the driving substrate and facing away from the driving substrate, and forming a color conversion layer in the grooves, the color conversion layer being used to convert light emitted by part of the micro LEDs into red light.

[0105] The preparation method of the micro display module provided by the embodiment of the present invention can reduce the process complexity and improve the mass production yield by transferring the entire pixel layer to the driving substrate and electrically connecting it to the driving substrate, instead of splicing and welding a single light-emitting chip on the driving substrate through mass transfer technology in the related art; moreover, a plurality of grooves are formed on the surface of the pixel layer farthest from the driving substrate away from the driving substrate, and a color conversion layer for converting part of the light emitted by the micro LED into red light is formed in the grooves, and part of the micro LED is used as an excitation pixel, and the light emitted by the excitation pixel excites the color conversion layer to emit red light, so that the combination of the excitation pixel and the color conversion layer can replace the micro LED that directly emits red light, and there is no need to prepare a red micro LED epitaxial structure, thereby reducing the process complexity, improving the mass production yield, and improving the problem that the preparation of red micro LEDs is difficult and the external quantum efficiency is low.

[0106] Optional, reference Figure 8 and Fig. 9 , before forming at least two pixel layers on the same side of the driving substrate in step S20, the method further includes: forming a common driving electrode 03b and a plurality of first driving electrodes 03a on the surface of the driving substrate 300; depositing a first dielectric layer 031, and polishing the interface of the dielectric layer flat by a chemical mechanical polishing (CMP) process, wherein the material of the first dielectric layer 031 may be a transparent non-conductive material such as silicon oxide or resin; depositing a second dielectric layer 032, and then etching through holes at the positions of the first driving electrode 03a and the common driving electrode 03b by an etching process, and depositing a metal material in the through holes by electroplating to form a conductive column, wherein the material of the second dielectric layer 032 may be a transparent non-conductive material such as silicon oxide or resin, and the metal material may be copper; polishing the interface between the second dielectric layer 032 and the conductive column flat by a CMP process, and completing the process flow of the wiring layer on the surface of the driving substrate 300.

[0107] Optionally, step S20 forms at least two pixel layers on the same side of the driving substrate, including:

[0108] S210, forming a first epitaxial structure on a first substrate, patterning the first epitaxial structure to form a plurality of green micro LEDs, forming a first passivation layer between adjacent green micro LEDs and on a side of the green micro LEDs away from the first substrate, and flattening the surface of the first passivation layer until the green micro LEDs are exposed to form a first pixel layer.

[0109] S220, forming a first wiring layer on a surface of the first pixel layer away from the first substrate, bonding the first pixel layer to the driving substrate with the side of the first wiring layer facing the driving substrate, removing the first substrate, and forming a second wiring layer on the exposed surface of the first pixel layer.

[0110] S230, forming a second epitaxial structure on the second substrate, patterning the second epitaxial structure to form a plurality of blue micro LEDs, forming a second passivation layer between adjacent blue micro LEDs and on a side of the blue micro LED away from the second substrate, and polishing the surface of the second passivation layer until the blue micro LEDs are exposed, thereby forming a second pixel layer;

[0111] S240, forming a third wiring layer on a surface of the second pixel layer away from the second substrate, facing the side of the second pixel layer having the third wiring layer toward the drive substrate, bonding to the second wiring layer, and removing the second substrate.

[0112] Specifically, in the embodiment of the present invention, there are two pixel layers, namely, a first pixel layer and a second pixel layer which are respectively away from the driving substrate in sequence; the first pixel layer includes a plurality of green micro LEDs emitting green light, and the second pixel layer includes a plurality of blue micro LEDs emitting blue light. After the process flow of the wiring layer on the surface of the driving substrate is completed, the preparation of the first pixel layer and the preparation of the second pixel layer are performed.

[0113] refer to Figure 10~Figure 12 The preparation steps for the first pixel layer include: forming a first epitaxial structure 1 on a first substrate 01, patterning the first epitaxial structure 1 to form a plurality of green micro LEDs 50G, forming a first passivation layer 101 between adjacent green micro LEDs 50G and on the side of the green micro LEDs 50G away from the first substrate 01, and polishing the surface of the first passivation layer 101 until the green micro LEDs 50G are exposed to form a first pixel layer 100. The material of the first substrate 01 may be silicon or sapphire, etc. The first epitaxial structure 1 includes a second semiconductor epitaxial layer 20, a quantum well epitaxial layer 30G for emitting green light, and a first semiconductor epitaxial layer 10, which are sequentially away from the first substrate 01. The first semiconductor epitaxial layer 10 and the second semiconductor epitaxial layer 20 are respectively an N-type semiconductor epitaxial layer and a P-type semiconductor epitaxial layer, or a P-type semiconductor epitaxial layer and an N-type semiconductor epitaxial layer. In the case where the first semiconductor epitaxial layer is a P-type semiconductor epitaxial layer, a current spreading layer 40 made of ITO can be sputtered on the surface of the first semiconductor epitaxial layer away from the first substrate 01 and annealed. Then, the current spreading layer 40 and the first epitaxial structure 1 are etched by photolithography and etching technology to etch out a plurality of green micro LEDs 50G; silicon oxide is deposited to passivate the side walls of the green micro LEDs and fill the gaps between adjacent micro LEDs 50, and the surface is polished flat by a CMP process to complete the preparation of the first pixel layer 100.

[0114] refer to Figure 13~Figure 15After forming the first pixel layer 100, a first wiring layer RDL1 is formed on the surface of the first pixel layer 100 away from the first substrate 01; wherein the first wiring layer RDL1 includes a plurality of conductive layers c1 electrically connected to the first semiconductor layer of the green micro LED 50G, a plurality of conductive layers c2 electrically connected to the first driving electrode 03a on the driving substrate and the first semiconductor layer of the blue micro LED, and a conductive layer c3 electrically connected to the common driving electrode 03b on the driving substrate and the first semiconductor layer of the micro LED. The side of the first pixel layer 100 having the first wiring layer RDL1 faces the driving substrate 300, and hybrid bonding is performed with the wiring layer on the surface of the driving substrate 300, and the first substrate 01 is removed.

[0115] refer to Fig.16 Then, a second wiring layer RDL2 is formed on the surface of the exposed first pixel layer 100, and a conductive column d1 for connecting the blue micro LED and the first driving electrode 03a is formed between adjacent green micro LEDs 50G, and a conductive column for electrically connecting the common driving electrode 03b is formed in the edge area of ​​the first pixel layer 100. The second wiring layer RDL2 includes a conductive layer c4 electrically connected to the second semiconductor layer of the green micro LED 50G, and the conductive layer c4 is electrically connected to the common driving electrode 03b through the wiring in the second wiring layer RDL2, the conductive column d2 located directly above the common driving electrode 03b in the first passivation layer 101, and the conductive column located directly above the common driving electrode 03b in the second dielectric layer 032, thereby realizing the electrical connection between the second semiconductor layer of the green micro LED 50G and the common driving electrode 03b.

[0116] The preparation steps of the second pixel layer can refer to the preparation process of the first pixel layer. Fig.17 , in the second epitaxial structure 2 formed on the surface of the second substrate 02, the quantum well epitaxial layer is a quantum well epitaxial layer 30B for emitting blue light; and reference Fig.18 In the process of patterning the second epitaxial structure 2, the second semiconductor epitaxial layer 20 is not etched or only partially etched, so that the second semiconductor layer 20' in each blue micro LED is a continuous film layer.

[0117] refer to Figure 18~Figure 20 After forming the second pixel layer 200, a third wiring layer RDL3 is formed on the surface of the second pixel layer 200 away from the second substrate 02, and the side of the second pixel layer 200 having the third wiring layer RDL3 is bonded to the second wiring layer RDL2 toward the driving substrate 300. During the bonding process, the oxygen-silicon region of the third wiring layer RDL3 is bonded to the oxygen-silicon region of the second wiring layer RDL2, and the conductive pillars in the third wiring layer RDL3 are aligned and bonded to the conductive pillars in the second wiring layer RDL2; then the second substrate 02 is removed.

[0118] The first wiring layer RDL1 , the second wiring layer RDL2 , and the third wiring layer RDL3 may be a single-layer film structure or a multi-layer film structure, and may be set according to actual conditions.

[0119] Optionally, step S30, forming a plurality of grooves on a surface of a pixel layer farthest from the driving substrate and facing away from the driving substrate, comprises:

[0120] S310, forming a plurality of grooves with curved bottom surfaces on a surface of the second semiconductor layer in the second pixel layer away from the driving substrate, wherein the curved surface bulges toward the color conversion layer.

[0121] Specifically, refer to Fig.21 In the second pixel layer 200, a plurality of grooves 601 with curved bottom surfaces are formed on the surface of the second semiconductor layer 20' away from the driving substrate 300, and the curved surface bulges toward the color conversion layer 60. The bottom surface of the groove 601 is set to be curved, and the curved surface bulges toward the color conversion layer 60, so that the bulge can be in the shape of a convex lens, and the light emitted by the micro LED located below it passes through this part of the second semiconductor layer, and the convex lens shape is used to improve the luminous efficiency and light intensity, and there is no need to set a separate lens, which simplifies the preparation process, saves preparation costs, and can also reduce the thickness of the micro display module, which is conducive to application in a micro display device; at the same time, compared with the bottom surface of the flat groove 601, the bottom surface of the curved groove 601 increases the area of ​​the bottom surface of the groove 601, so that the contact area between the color conversion layer 60 and the bottom surface of the groove 601 is larger, the excitation efficiency of the color conversion layer 60 is improved, and the color conversion layer 60 is more stably and reliably arranged in the groove 601.

[0122] Note that the above are only preferred embodiments of the present invention and the technical principles used. Those skilled in the art will understand that the present invention is not limited to the specific embodiments described herein, and that various obvious changes, readjustments and substitutions can be made by those skilled in the art without departing from the scope of protection of the present invention. Therefore, although the present invention has been described in more detail through the above embodiments, the present invention is not limited to the above embodiments, and may include more other equivalent embodiments without departing from the concept of the present invention, and the scope of the present invention is determined by the scope of the appended claims.

Claims

1. A micro display module, characterized in that: include: Driver substrate; At least two stacked pixel layers are bonded to the same side of the drive substrate and have a flat interface between adjacent pixel layers; Each of the pixel layers comprises a micro LED array and a passivation layer between the micro LEDs, and the micro LEDs are electrically connected to the driving substrate; The surface of the pixel layer farthest from the driving substrate on the side away from the driving substrate comprises a plurality of grooves, and a color conversion layer for converting part of the light emitted by the micro LEDs into red light is arranged in the grooves.

2. The micro display module according to claim 1, characterized in that: The bottom surface of the groove is a curved surface, and the curved surface is convex toward the color conversion layer; And / or, the thickness of the color conversion layer is equal to the depth of the groove.

3. The micro display module according to claim 1, characterized in that: Each of the micro-LEDs comprises: A first semiconductor layer, located on one side of the driving substrate; A quantum well layer, located on a side of the first semiconductor layer away from the driving substrate; A second semiconductor layer is located on a side of the quantum well layer away from the driving substrate; Wherein, at least the second semiconductor layer in the pixel layer farthest from the driving substrate is a continuous film layer, and the groove is located on a side of the second semiconductor layer in the pixel layer farthest from the driving substrate away from the driving substrate.

4. The micro display module according to claim 3, characterized in that: A vertical projection of each color conversion layer on the driving substrate at least partially overlaps with a vertical projection of a micro LED in a pixel layer farthest from the driving substrate on the driving substrate; The light emitted by the micro LED in the pixel layer farthest from the driving substrate is blue light.

5. The micro display module according to claim 1, characterized in that: The number of pixel layers is two, which are a first pixel layer and a second pixel layer which are respectively away from the driving substrate in sequence; The first pixel layer includes a plurality of green micro LEDs emitting green light, and the second pixel layer includes a plurality of blue micro LEDs emitting blue light; wherein the number of the blue micro LEDs is greater than or equal to the number of the green micro LEDs.

6. The micro display module according to claim 5, characterized in that: A blue micro LED is disposed above each of the two opposite sides of each of the green micro LEDs, and a vertical projection of the color conversion layer on the driving substrate at least partially overlaps with a vertical projection of one of the blue micro LEDs on the driving substrate; Wherein, the vertical projections of the two blue micro LEDs located above the green micro LED on the driving substrate do not overlap with the vertical projection of the green micro LED on the driving substrate; Alternatively, a vertical projection of at least one of the two blue micro LEDs located above the green micro LED on the driving substrate at least partially overlaps with a vertical projection of the green micro LED on the driving substrate.

7. The micro display module according to claim 5, characterized in that: The second pixel layer includes a plurality of annular blue micro LEDs, and a vertical projection of each of the annular blue micro LEDs on the driving substrate corresponds to and surrounds a vertical projection of a green micro LED on the driving substrate; the vertical projection of the color conversion layer on the driving substrate is located on one side of the vertical projection of the green micro LED on the driving substrate, and partially overlaps with the vertical projection of the annular blue micro LED on the driving substrate; Alternatively, the second pixel layer includes a plurality of annular blue micro LEDs and a plurality of central blue micro LEDs, each of the central blue micro LEDs being surrounded by a corresponding annular blue micro LED; a vertical projection of the central blue micro LED on the driving substrate at least partially overlaps with a vertical projection of the green micro LED on the driving substrate; wherein a vertical projection of the color conversion layer on the driving substrate at least partially overlaps with a vertical projection of the central blue micro LED on the driving substrate, or a vertical projection of the color conversion layer on the driving substrate partially overlaps with a vertical projection of the annular blue micro LED on the driving substrate.

8. The micro display module according to claim 3, characterized in that: The surface of the driving substrate includes a plurality of first driving electrodes and a common driving electrode; Each of the micro LEDs is electrically connected to a corresponding first driving electrode through a first electrode connector, and each of the micro LEDs is also electrically connected to the common driving electrode through a common electrode connector; Among them, at least the second semiconductor layer in the pixel layer farthest from the driving substrate contacts the common electrode connector; the first electrode connector is composed of at least one of a conductive column and a conductive layer; the common electrode connector is composed of at least one of a conductive column and a conductive layer.

9. A method for preparing a micro display module, characterized in that: include: Providing a drive substrate; forming at least two pixel layers on the same side of the driving substrate; There is a flat interface between adjacent pixel layers, each of the pixel layers comprises a micro-LED array and a passivation layer between the micro-LEDs, and the micro-LEDs are electrically connected to the driving substrate; A plurality of grooves are formed on a surface of a pixel layer farthest from the driving substrate and away from the driving substrate, and a color conversion layer is formed in the grooves. The color conversion layer is used to convert light emitted by part of the micro LEDs into red light.

10. The method for preparing a micro display module according to claim 9, characterized in that: The at least two pixel layers are formed on the same side of the driving substrate, comprising: Forming a first epitaxial structure on a first substrate, patterning the first epitaxial structure to form a plurality of green micro LEDs, forming a first passivation layer between adjacent green micro LEDs and on a side of the green micro LEDs away from the first substrate, and polishing the surface of the first passivation layer until the green micro LEDs are exposed to form a first pixel layer; forming a first wiring layer on a surface of the first pixel layer away from the first substrate, bonding the first pixel layer with the first wiring layer facing the drive substrate, removing the first substrate, and forming a second wiring layer on the exposed surface of the first pixel layer; forming a second epitaxial structure on a second substrate, patterning the second epitaxial structure to form a plurality of blue micro LEDs, forming a second passivation layer between adjacent blue micro LEDs and on a side of the blue micro LEDs away from the second substrate, and flattening a surface of the second passivation layer until the blue micro LEDs are exposed, thereby forming a second pixel layer; forming a third wiring layer on a surface of the second pixel layer away from the second substrate, bonding the second pixel layer with the third wiring layer on a side facing the drive substrate to the second wiring layer, and removing the second substrate; The forming of a plurality of grooves on a surface of a pixel layer farthest from the driving substrate and away from the driving substrate comprises: A plurality of grooves having a curved bottom are formed on a surface of the second semiconductor layer at a side away from the driving substrate in the second pixel layer, and the curved bottom is convex toward the color conversion layer.

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