Miniature light-emitting device and manufacturing method thereof

Abstract

The invention relates to a miniature light-emitting device and a manufacturing method thereof. The miniature light-emitting device comprises a driving substrate and at least one first bonding layer arranged on one side of the driving substrate. The light emitting device comprises at least one light emitting structure and at least one second bonding layer arranged on one side of the at least one light emitting structure, and the at least one second bonding layer is correspondingly bonded with the at least one first bonding layer to form at least one bonding layer stacked structure, each bonding layer stacking structure is composed of a second bonding layer and a first bonding layer which are correspondingly bonded; at least one buffer adhesive layer, wherein a corresponding buffer adhesive layer is arranged between the first bonding layer and the second bonding layer in each bonding layer stacking structure; moreover, the surface, deviating from the driving substrate, of the first bonding layer and / or the surface, deviating from the light-emitting structure, of the second bonding layer partially protrude to form bonding salient points, and the buffer adhesive layer corresponding to each bonding layer stacking structure is filled in the sunken part around the bonding salient points in each bonding layer stacking structure.

Description

Technical Field

[0001] This application relates to the field of semiconductor light-emitting technology, specifically to a micro light-emitting device and its fabrication method. Background Technology

[0002] Micro-LED (Micro Light Emitting Diode) chip arrays typically refer to chip arrays formed on the epitaxial wafer of a single LED (Light Emitting Diode) through processes such as photolithography, etching, evaporation, and dicing. Micro-LED chip arrays used in microdisplays are generally several millimeters to tens of millimeters in size. Compared to current display devices such as LCD (Liquid Crystal Display) and OLED (Organic Light Emitting Display), Micro-LED display devices have significant advantages such as fast response, high color gamut, high PPI (Pixels per inch), high brightness, and low power consumption, and can be widely used in AR (Augmented Reality) / VR (Virtual Reality) microdisplays and wearable microdisplays.

[0003] However, existing manufacturing processes for Micro-LED display devices suffer from low product yield. Summary of the Invention

[0004] This application provides a micro light-emitting device and its fabrication method to improve the existing manufacturing process of Micro-LED display devices. This improves the problem of silicon-based driver IC wafers being prone to breakage and dark cracks after bonding sapphire-based LED epitaxial wafers with silicon-based driver IC wafers, thereby increasing product yield.

[0005] This application provides a micro-light-emitting device, comprising: a driving substrate and at least one first bonding layer disposed on one side of the driving substrate; at least one light-emitting structure and at least one second bonding layer, wherein the at least one second bonding layer is disposed on one side of the at least one light-emitting structure and is respectively disposed corresponding to the at least one light-emitting structure, and the at least one second bonding layer is correspondingly bonded to the at least one first bonding layer to form at least one bonding layer stack structure, so as to realize the at least one light-emitting structure bonded to one side of the driving substrate where the at least one first bonding layer is disposed. On the side, each of the bonding layer stack structures is composed of a correspondingly bonded second bonding layer and a first bonding layer; at least one buffer adhesive layer is provided between the first bonding layer and the second bonding layer in each of the bonding layer stack structures; and in each of the bonding layer stack structures, the surface of the first bonding layer away from the driving substrate and / or the surface of the second bonding layer away from the light-emitting structure are partially raised to form bonding bumps, and the buffer adhesive layer corresponding to each of the bonding layer stack structures fills the recessed portion around the bonding bumps in each of the bonding layer stack structures.

[0006] In each of the bonding layer stack structures, a first bonding bump is formed on a partial protrusion of the surface of the first bonding layer away from the driving substrate, and a second bonding bump is formed on a partial protrusion of the surface of the second bonding layer away from the light-emitting structure. The first bonding bump and the second bonding bump are bonded together, and there is an opposing region between the first bonding bump and the second bonding bump. Furthermore, the buffer adhesive layer corresponding to each of the bonding layer stack structures is located outside the opposing region between the first bonding bump and the second bonding bump in each of the bonding layer stack structures.

[0007] In each of the bonding layer stack structures, the first bonding bump is formed by protruding from the central region of the surface of the first bonding layer away from the driving substrate, and the second bonding bump is formed by protruding from the central region of the surface of the second bonding layer away from the light-emitting structure. The surface of the first bonding bump away from the driving substrate and the surface of the second bonding bump away from the light-emitting structure have the same shape and size.

[0008] The micro light-emitting device further includes at least one conductive adhesive layer, wherein a corresponding conductive adhesive layer is provided between the first bonding layer and the second bonding layer in each bonding layer stack structure, and the conductive adhesive layer corresponding to each bonding layer stack structure electrically connects the first bonding layer and the second bonding layer in each bonding layer stack structure.

[0009] In each of the bonding layer stack structures, the conductive adhesive layer and the buffer adhesive layer together completely fill the gap between the first bonding layer and the second bonding layer in each bonding layer stack structure.

[0010] The micro-light-emitting device further includes: at least one first adhesive layer and at least one first blocking layer, wherein the at least one first adhesive layer is located between the driving substrate and the at least one first bonding layer and is respectively disposed corresponding to the at least one first bonding layer, and the at least one first blocking layer is located between the at least one first adhesive layer and the at least one first bonding layer and is respectively disposed corresponding to the at least one first bonding layer; and at least one second adhesive layer and at least one second blocking layer, wherein the at least one second adhesive layer is located between the at least one light-emitting structure and the at least one second bonding layer and is respectively disposed corresponding to the at least one second bonding layer, and the at least one second blocking layer is located between the at least one second adhesive layer and the at least one second bonding layer and is respectively disposed corresponding to the at least one second bonding layer.

[0011] This application also provides a method for fabricating a micro-light-emitting device. The method includes: providing a driving substrate and a light-emitting epitaxial wafer, wherein the light-emitting epitaxial wafer includes a substrate and a light-emitting stack disposed on one side of the substrate; forming a first bonding layer on one side of the driving substrate and forming a second bonding layer on the side of the light-emitting stack facing away from the substrate; wherein the surface of the first bonding layer facing away from the driving substrate is a first bonding surface, and the surface of the second bonding layer facing away from the light-emitting stack is a second bonding surface; and at least one bonding bump is formed at at least one designated position on the first bonding surface and / or the second bonding surface; forming a buffer adhesive layer on the first bonding surface and / or the second bonding surface; bonding the first bonding surface and the second bonding surface to form a bonding structure, wherein during the bonding process, the buffer adhesive layer is squeezed to the periphery of the bonding bump by the bonding bump; removing the substrate of the light-emitting epitaxial wafer from the bonding structure to expose the light-emitting stack; and fabricating a micro-light-emitting device based on the bonding structure after removing the substrate.

[0012] The driving substrate includes at least one driving electrode disposed on one side of the driving substrate, and the first bonding surface has at least one first bonding bump formed at a position corresponding to the at least one driving electrode; the light-emitting stack has at least one light-emitting region, and the second bonding surface has at least one second bonding bump formed at a position corresponding to the at least one light-emitting region; and each second bonding bump corresponds to one first bonding bump; the step of bonding the first bonding surface and the second bonding surface to form a bonding structure includes: bonding the second bonding bump to the corresponding first bonding bump to form a bonding structure.

[0013] The step of forming a buffer adhesive layer on the first bonding surface and / or the second bonding surface includes: coating a layer of buffer adhesive on the first bonding surface and removing the solvent from the coated buffer adhesive to obtain a buffer adhesive layer in a pre-cured state; and during the bonding process, the buffer adhesive layer changes from a pre-cured state to a fully cured state; after forming the buffer adhesive layer on the first bonding surface and / or the second bonding surface, and before bonding the first bonding surface and the second bonding surface to form a bonding structure, the method further includes: forming a conductive adhesive layer on the surface of the buffer adhesive layer facing away from the second bonding surface; and during the bonding process, the conductive adhesive layer is squeezed by the first bonding bump and the second bonding bump to electrically connect the first bonding bump to the corresponding second bonding bump.

[0014] The method of fabricating a micro-light-emitting device based on the bonding structure after substrate removal includes: forming a groove penetrating the driving substrate on the side of the exposed light-emitting stack opposite to the driving substrate, wherein the orthographic projection of the groove on the driving substrate surrounds the orthographic projection of each light-emitting region on the driving substrate, so as to divide all film layer structures on the driving substrate as a whole into at least one light-emitting unit; forming a passivation layer, wherein the passivation layer at least covers the sidewall of each light-emitting unit; and forming an electrode layer on the side of the passivation layer opposite to the driving substrate and on the side of the at least one light-emitting unit opposite to the driving substrate, wherein the electrode layer is electrically connected to the light-emitting stack in each light-emitting unit.

[0015] The beneficial effects of this application are as follows: The micro-light-emitting device and its fabrication method provided in this application, through optimized bonding layer structure design, introduce a buffer adhesive layer at the bonding interface and combine it with a local bump design for the bonding bumps. This allows the bonding bumps to achieve electrical interconnection during the bonding process, while the buffer adhesive layer fills the peripheral gaps of the bonding bumps and absorbs stress caused by thermal mismatch. This not only reduces interface stress concentration but also allows the buffer adhesive layer to act as a buffer during the bonding process, absorbing and dispersing stress. This effectively alleviates the stress concentration problem caused by the difference in thermal expansion coefficients between the substrate materials of the sapphire-based LED epitaxial wafer and the silicon-based driver IC wafer, significantly reducing the breakage rate and dark crack risk of the silicon-based driver IC wafer after bonding, and improving product yield, structural stability, and reliability. In addition, the local bump design of the bonding bumps makes the bonding process more precise and controllable, further improving the reliability and yield of the bonding, thus contributing to improved product reliability and yield. Attached Figure Description

[0016] To more clearly illustrate the technical solutions in the embodiments of this application, the accompanying drawings used in the description of the embodiments will be briefly introduced below. Obviously, the accompanying drawings described below are only some embodiments of this application. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0017] Figure 1 This is a schematic cross-sectional view of the micro light-emitting device provided in the embodiments of this application; Figure 2 This is another cross-sectional structural schematic diagram of the micro light-emitting device provided in the embodiments of this application; Figure 3 This is another cross-sectional structural schematic diagram of the micro light-emitting device provided in the embodiments of this application; Figure 4 This is a schematic flowchart of the fabrication method of the micro light-emitting device provided in the embodiments of this application; Figure 5 This is a schematic cross-sectional view of the driving substrate provided in an embodiment of this application; Figure 6 This is a schematic cross-sectional view of the light-emitting epitaxial wafer provided in an embodiment of this application; Figure 7 This is a schematic cross-sectional view of the structure after the formation of the first bonding layer provided in an embodiment of this application; Figure 8 This is a schematic cross-sectional view of the structure after the formation of the second bonding layer provided in an embodiment of this application; Figure 9 This is a schematic cross-sectional view of the structure after forming the buffer adhesive layer and the conductive adhesive layer according to an embodiment of this application; Figure 10This is a schematic cross-sectional view of the structure after aligning the first bonding bump and the second bonding bump, as provided in an embodiment of this application. Figure 11 This is a cross-sectional schematic diagram of the bonding structure provided in the embodiments of this application; Figure 12 This is a cross-sectional schematic diagram of the bonding structure after removing the substrate, provided in an embodiment of this application. Detailed Implementation

[0018] The technical solutions of the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of this application, and not all of them. All other embodiments obtained by those skilled in the art based on the embodiments of this application without creative effort are within the scope of protection of this application.

[0019] The embodiments of this application will be further described in detail below with reference to the accompanying drawings and examples. It should be particularly noted that the following embodiments are only used to illustrate the embodiments of this application and do not limit the scope of the embodiments of this application. Similarly, the following embodiments are only some embodiments of the embodiments of this application, and not all embodiments. All other embodiments obtained by those skilled in the art without creative effort are within the protection scope of the embodiments of this application.

[0020] In the embodiments of this application, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined as "first" or "second" may explicitly or implicitly include one or more of the stated features. In the description of this application, "multiple" means two or more, unless otherwise explicitly specified.

[0021] In the following description, the connection of the second component to the first component may include embodiments in which the second component is directly connected to the first component, and may also include embodiments in which the second component is connected to the first component via an additional component, such that the second component is not directly connected to the first component.

[0022] In the following description, the connection between the second component and the first component may include embodiments in which the second component is directly connected to the first component, and may also include embodiments in which the second component is connected to the first component via an additional component, thereby preventing the second component from being directly connected to the first component.

[0023] When describing the structure of a component, when referring to a layer or region as being "above" or "on top of" another layer or region, it can mean that it is directly above the other layer or region, or that it contains other layers or regions between itself and the other layer or region. Furthermore, if the component is flipped, the layer or region will be located "below" or "under" the other layer or region. Additionally, the features, structures, or characteristics described below can be combined in any suitable manner in one or more embodiments.

[0024] Furthermore, the directional terms mentioned in the embodiments of this application, such as [up], [down], [front], [back], [left], [right], [inner], [outer], [side], etc., are only for reference to the accompanying drawings. Therefore, the directional terms used are for illustrating and understanding the embodiments of this application, and not for limiting the embodiments of this application. In the various drawings, structurally similar units are represented by the same reference numerals. For clarity, the various parts in the drawings are not drawn to scale. In addition, some related parts may not be shown in the drawings.

[0025] Micro-LED chip arrays typically refer to arrays of chips formed on a single LED epitaxial wafer through processes such as photolithography, etching, evaporation, and dicing. Micro-LED chip arrays used in microdisplays are generally several millimeters to tens of millimeters in size. Compared to current display devices such as LCD and OLED, Micro-LED display devices have significant advantages such as rapid response, high color gamut, high PPI, high brightness, and low power consumption, and can be widely used in AR / VR microdisplays and wearable microdisplays.

[0026] Currently, conventional LED epitaxial wafers use sapphire as the substrate, which is cheaper than silicon-based LED epitaxial wafers. Conventional driver IC (Integrated Circuit) wafers use silicon as the substrate. However, sapphire and silicon have a thermal expansion coefficient that differs by 2 to 3 times, a significant difference. This mismatch in material properties can cause uneven stress distribution during the bonding process between sapphire-based LED epitaxial wafers and silicon-based driver IC wafers. This can lead to breakage and dark cracks in the silicon-based driver IC wafers after bonding, affecting product yield.

[0027] To address the above problems, this application provides a micro-light-emitting device and its fabrication method. By optimizing the bonding layer structure design, a buffer adhesive layer is introduced at the bonding interface, along with a localized protrusion design for the bonding bumps. This allows the bonding bumps to achieve electrical interconnection during the bonding process, while the buffer adhesive layer fills the peripheral gaps of the bonding bumps and absorbs stress caused by thermal mismatch. This not only reduces interface stress concentration but also allows the buffer adhesive layer to act as a buffer during the bonding process, absorbing and dispersing stress. This effectively alleviates the stress concentration problem caused by the difference in thermal expansion coefficients between the substrate materials of the sapphire-based LED epitaxial wafer and the silicon-based driver IC wafer, significantly reducing the breakage rate and dark crack risk of the silicon-based driver IC wafer after bonding, and improving product yield, structural stability, and reliability. Furthermore, the localized protrusion design of the bonding bumps makes the bonding process more precise and controllable, further improving the reliability and yield of the bonding, thus contributing to improved product reliability and yield.

[0028] The following detailed description is based on specific embodiments. It should be noted that the embodiments of this application can be presented in various forms, and some examples will be described below.

[0029] Please see Figure 1 , Figure 1 This is a cross-sectional structural diagram of the micro light-emitting device provided in the embodiments of this application. For example... Figure 1 As shown, the micro-light-emitting device 1 includes a driving substrate 10, at least one light-emitting structure 20A, at least one buffer adhesive layer 30A, at least one first bonding layer 40A, and at least one second bonding layer 50A. The at least one first bonding layer 40A is disposed on one side of the driving substrate 10, and the at least one second bonding layer 50A is disposed on one side of the at least one light-emitting structure 20A, corresponding to the at least one light-emitting structure 20A. Furthermore, the at least one second bonding layer 50A is bonded to the at least one first bonding layer 40A to form at least one bonding layer stack structure 100, thereby enabling the at least one light-emitting structure 20A to be bonded to the side of the driving substrate 10 where the at least one first bonding layer 40A is disposed. Each bonding layer stack structure 100 consists of one correspondingly bonded second bonding layer 50A and one correspondingly bonded first bonding layer 40A, and a corresponding buffer adhesive layer 30A is provided between the first bonding layer 40A and the second bonding layer 50A in each bonding layer stack structure 100.

[0030] Specifically, in each bonding layer stack structure 100, bonding bumps 401 / 501 are formed on the surface of the first bonding layer 40A facing away from the driving substrate 10 (i.e., the upper surface) and / or the surface of the second bonding layer 50A facing away from the light-emitting structure 20A (i.e., the lower surface). Furthermore, for each bonding layer stack structure 100, a buffer adhesive layer 30A corresponding to the bonding layer stack structure 100 is located between the first bonding layer 40A and the second bonding layer 50A in the bonding layer stack structure 100, and the orthographic projection of the buffer adhesive layer 30A corresponding to the bonding layer stack structure 100 on the driving substrate 10 surrounds the orthographic projection of the bonding bumps 401 / 501 in the bonding layer stack structure 100 on the driving substrate 10. Specifically, the buffer adhesive layer 30A corresponding to the bonding layer stack structure 100 can fill the recessed areas around the bonding bumps 401 / 501 in the bonding layer stack structure 100.

[0031] In this way, by introducing a buffer adhesive layer 30A at the bonding interface and coordinating it with the localized protrusion design of the bonding bumps 401 / 501, the bonding bumps 401 / 501 achieve electrical interconnection during the bonding process. Simultaneously, the buffer adhesive layer 30A effectively fills the peripheral gaps of the bonding bumps 401 / 501 and absorbs stress caused by thermal mismatch, thereby reducing interface stress concentration. Furthermore, the surrounding arrangement of the buffer adhesive layer 30A prevents external impurities from intruding into the bonding interface, improving structural stability and long-term reliability.

[0032] In addition, by controlling the thickness and coverage of the buffer adhesive layer 30A, it can be made not to interfere with the connection reliability of the bonding bumps 401 / 501, while fully covering the non-bonded areas, further improving structural stability and resistance to mechanical shock, making it suitable for high-density, miniaturized display applications.

[0033] Specifically, in the aforementioned micro-light-emitting device 1, each light-emitting structure 20A may include a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 stacked sequentially. The at least one second bonding layer 50A may be disposed on the side of the second semiconductor layer 23 facing away from the light-emitting layer 22 in the at least one light-emitting structure 20A. The light-emitting layer 22 may be a quantum well layer, for example, an indium gallium nitride (IGaN) quantum well layer, or an IGaN / GaN multi-quantum well layer. The first semiconductor layer 21 and the second semiconductor layer 23 have different polarities. Specifically, the first semiconductor layer 21 may be one of an N-type semiconductor layer and a P-type semiconductor layer, and the second semiconductor layer 23 may be the other of an N-type semiconductor layer and a P-type semiconductor layer. Specifically, the N-type semiconductor layer may be an N-type gallium nitride layer or an N-type gallium arsenide layer, and the P-type semiconductor layer may be a P-type gallium nitride layer or a P-type aluminum gallium nitride layer.

[0034] Specifically, such as Figure 1As shown, in the micro light-emitting device 1, the driving substrate 10 may include at least one driving electrode 11 disposed on one side of the driving substrate 10. The at least one first bonding layer 40A may be specifically disposed on the side of the driving substrate 10 where the at least one driving electrode 11 is disposed, and is disposed corresponding to the at least one driving electrode 11.

[0035] Specifically, each driving electrode 11 may correspond to a first bonding layer 40A, a second bonding layer 50A, and a light-emitting structure 20A. Furthermore, for each driving electrode 11, the first bonding layer 40A, the second bonding layer 50A, and the light-emitting structure 20A corresponding to the driving electrode 11 are sequentially stacked above the driving electrode 11. The first bonding layer 40A corresponding to the driving electrode 11 is electrically connected to the driving electrode 11, and the first bonding layer 40A corresponding to the driving electrode 11 is bonded to the second bonding layer 50A corresponding to the driving electrode 11 to form a bonding layer stack structure 100. The second bonding layer 50A corresponding to the driving electrode 11 is electrically connected to the light-emitting structure 20A corresponding to the driving electrode 11 (for example, the second semiconductor layer 23 in the light-emitting structure 20A corresponding to the driving electrode 11). Thus, the driving substrate 10 can provide driving signals to the light-emitting structure 20A corresponding to the driving electrode 11 through the driving electrode 11 and the first bonding layer 40A and the second bonding layer 50A corresponding to the driving electrode 11 to drive the light-emitting structure 20A corresponding to the driving electrode 11 to emit light, thereby realizing the display function of the micro light-emitting device 1.

[0036] In some examples, the driving substrate 10 may be a driving chip or a driving wafer. The driving electrode 11 may be made of conductive materials such as titanium (Ti), aluminum (Al), gold (Au), platinum (Pt), and / or nickel (Ni).

[0037] In this embodiment, the first bonding layer 40A can be made of a metallic material, such as at least one selected from nickel (Ni), silver (Ag), gold (Au), tin (Sn), aluminum (Al), and indium (In). The second bonding layer 50A can also be made of a metallic material, such as at least one selected from nickel (Ni), silver (Ag), gold (Au), tin (Sn), aluminum (Al), and indium (In). Furthermore, in specific implementations, the first bonding layer 40A and the second bonding layer 50A can be made of the same material or different materials to adapt to different bonding process requirements and thermal expansion coefficient matching.

[0038] It should be noted that this embodiment does not limit the specific material of the buffer adhesive layer 30A. The buffer adhesive layer 30 can be made of materials with good buffering properties and chemical stability, such as epoxy resin or polyimide (PI), which effectively alleviates the stress caused by the difference in thermal expansion coefficients during bonding. It also has excellent adhesion and environmental resistance, ensuring the reliability of the device during long-term operation. At the same time, this type of material has good insulation properties, which can prevent current leakage between bonding areas and improve device reliability.

[0039] In some embodiments, both the first bonding layer 40A, which faces away from the surface of the driving substrate 10, and the second bonding layer 50A, which faces away from the surface of the light-emitting structure 20A, may be locally raised to form bonding bumps 401 / 501. For example, as... Figure 1 As shown, in each bonding layer stack structure 100, the surface of the first bonding layer 40A facing away from the driving substrate 10 has a local protrusion to form a first bonding bump 401, and the surface of the second bonding layer 50A facing away from the light-emitting structure 20A has a local protrusion to form a second bonding bump 501.

[0040] In other embodiments, only one of the surfaces of the first bonding layer 40A facing away from the driving substrate 10 and the second bonding layer 50A facing away from the light-emitting structure 20A may have a partial protrusion forming bonding bumps 401 / 501. For example, in each bonding layer stack structure 100, the surface of the first bonding layer 40A facing away from the driving substrate 10 has a partial protrusion forming a first bonding bump 401, while the surface of the second bonding layer 50A facing away from the light-emitting structure 20A can be a flat surface. As another example, in each bonding layer stack structure 100, the surface of the second bonding layer 50A facing away from the light-emitting structure 20A has a partial protrusion forming a second bonding bump 501, while the surface of the first bonding layer 40A facing away from the driving substrate 10 can be a flat surface.

[0041] In some examples, such as Figure 1 As shown, in each bonding layer stack structure 100, the first bonding bump 401 can be specifically formed by protruding from the central region of the surface of the first bonding layer 40A away from the driving substrate 10, and the second bonding bump 501 can be specifically formed by protruding from the central region of the surface of the second bonding layer 50A away from the light-emitting structure 20A. This facilitates better alignment and contact of the bonding bumps 401 / 501 during bonding, improving bonding accuracy and reliability. Simultaneously, the design of the central region protrusion helps to further disperse stress, reducing the risk of breakage or dark cracking due to stress concentration.

[0042] In some examples, the bonding bumps 401 / 501 (i.e., the first bonding bump 401 and the second bonding bump 501) can be columnar structures extending along the longitudinal direction Z perpendicular to the driving substrate 10. Specifically, the cross-sectional shape of the bonding bumps 401 / 501 perpendicular to the longitudinal direction Z can be a geometric shape such as a circle, hexagon, square, or pentagon.

[0043] Specifically, in the above embodiment where a first bonding bump 401 is formed on a partial protrusion of the surface of the first bonding layer 40A facing away from the driving substrate 10, and a second bonding bump 501 is formed on a partial protrusion of the surface of the second bonding layer 50A facing away from the light-emitting structure 20A, as shown in the example... Figure 1 As shown, in each bonding layer stack structure 100, a first bonding bump 401 is bonded to a second bonding bump 501, and there is an opposing region between the first bonding bump 401 and the second bonding bump 501. Furthermore, for each bonding layer stack structure 100, the corresponding buffer adhesive layer 30A is located outside this opposing region. This layout design ensures a stable and reliable electrical connection between the bonding bumps 401 / 501, while providing comprehensive protection for the non-bonded areas through the buffer adhesive layer 30A.

[0044] Furthermore, in specific implementation, for each bonding layer stack structure 100, the surface of the first bonding bump 401 facing away from the driving substrate 10 in the bonding layer stack structure 100 can have the same shape and size as the surface of the second bonding bump 501 facing away from the light-emitting structure 20A in the bonding layer stack structure 100. This ensures that the orthographic projection of the surface of the first bonding bump 401 facing away from the driving substrate 10 in the bonding layer stack structure 100 on the driving substrate 10 can completely overlap with the orthographic projection of the surface of the second bonding bump 501 facing away from the light-emitting structure 20A in the bonding layer stack structure 100 on the driving substrate 10. In other words, it ensures that the surface of the first bonding bump 401 facing away from the driving substrate 10 in the bonding layer stack structure 100 can be completely aligned with the surface of the second bonding bump 501 facing away from the light-emitting structure 20A in the bonding layer stack structure 100. This perfectly aligned design maximizes the contact area between bonding bumps 401 / 501, thereby enhancing bonding strength and improving the stability of electrical interconnects. Simultaneously, the perfectly aligned layout helps to further evenly distribute stress, reducing the risk of structural failure due to uneven stress distribution. In practice, by precisely controlling bonding process parameters such as temperature, pressure, and time, high-precision perfect alignment of bonding bumps 401 / 501 can be ensured, thus improving the performance and reliability of the entire micro-light-emitting device 1. Furthermore, this design has a certain degree of fault tolerance; even minor positional deviations during bonding will not significantly affect bonding quality, thereby improving production yield and product consistency.

[0045] In some embodiments, such as Figure 1 As shown, the aforementioned micro-light-emitting device 1 may further include at least one conductive adhesive layer 110A. Furthermore, in the micro-light-emitting device 1, a corresponding conductive adhesive layer 110A is provided between the first bonding layer 40A and the second bonding layer 50A in each of the aforementioned bonding layer stack structures 100. Specifically, for each bonding layer stack structure 100, the conductive adhesive layer 110A corresponding to the bonding layer stack structure 100 is located between the first bonding layer 40A and the second bonding layer 50A in the bonding layer stack structure 100, and electrically connects the first bonding layer 40A and the second bonding layer 50A in the bonding layer stack structure 100. The conductive adhesive layer 110A corresponding to the bonding layer stack structure 100 not only plays an electrical conduction role, but also absorbs and disperses the residual stress at the bonding interface between the first bonding layer 40A and the second bonding layer 50A in the bonding layer stack structure 100 through its elastic properties. This forms a synergistic buffering effect with the buffer adhesive layer 30A corresponding to the bonding layer stack structure 100, further reducing the risk of damage or micro-cracks caused by stress concentration, and further improving the product yield, structural stability and reliability.

[0046] Specifically, for each bonding layer stack 100, the conductive adhesive layer 110A corresponding to the bonding layer stack 100 is located between the first bonding layer 40A and the second bonding layer 50A in the bonding layer stack 100, and the buffer adhesive layer 30A corresponding to the bonding layer stack 100 can be specifically located between the conductive adhesive layer 110A corresponding to the bonding layer stack 100 and the first bonding layer 40A in the bonding layer stack 100, or can be specifically located between the conductive adhesive layer 110A corresponding to the bonding layer stack 100 and the second bonding layer 50A in the bonding layer stack 100. Furthermore, the conductive adhesive layer 110A corresponding to the bonding layer stack 100 and the buffer adhesive layer 30A corresponding to the bonding layer stack 100 can together fill most or completely fill the gap between the first bonding layer 40A and the second bonding layer 50A in the bonding layer stack 100. Thus, the synergistic effect of the conductive adhesive layer 110A and the buffer adhesive layer 30A can further optimize the stress distribution at the bonding interface. Through elastic deformation and buffer energy absorption, it effectively reduces the stress concentration phenomenon at the interface caused by the difference in thermal expansion coefficients. This layered filling structure not only improves the mechanical stability of the bonding area, but also ensures the reliability of signal transmission through the electrical connection function of the conductive adhesive layer 110A. In practical applications, the thickness ratio of the corresponding conductive adhesive layer 110A to the corresponding buffer adhesive layer 30A can be adjusted according to the material characteristics of the bonding layers 40A / 50A. For example, when the first bonding layer 40A uses a high thermal conductivity metal, the proportion of the corresponding buffer adhesive layer 30A can be appropriately increased to enhance the stress buffering effect, while maintaining the minimum necessary thickness of the corresponding conductive adhesive layer 110A to ensure electrical performance. Through this dynamic design strategy, the micro-light-emitting device 1 can maintain stable bonding quality under different operating conditions, significantly improving the product's adaptability to high-density display scenarios.

[0047] In some examples, the conductive adhesive layer 110A may include anisotropic conductive adhesive (ACF) or anisotropic conductive film (ACA) containing conductive particles, which enable conductivity between the first bonding layer 40A and the second bonding layer 50A under pressure and temperature, while ensuring the stability and reliability of the electrical connection. Furthermore, the conductive adhesive layer 110A also provides mechanical fixation and cushioning, improving the overall structural strength and durability of the device.

[0048] In some embodiments, such as Figure 1As shown, the aforementioned micro-light-emitting device 1 may further include at least one first adhesive layer 60A and at least one first blocking layer 70A. Furthermore, in the micro-light-emitting device 1, the at least one first adhesive layer 60A is located between the driving substrate 10 and the at least one first bonding layer 40A, and is respectively disposed corresponding to the at least one first bonding layer 40A; the at least one first blocking layer 70A is located between the at least one first adhesive layer 60A and the at least one first bonding layer 40A, and is respectively disposed corresponding to the at least one first bonding layer 40A.

[0049] Thus, by providing a first adhesion layer 60A between the driving substrate 10 and the first bonding layer 40A, the first adhesion layer 60A can enhance the bonding force between the first bonding layer 40A and the driving substrate 10, preventing the first bonding layer 40A from detaching or shifting during manufacturing or use. Furthermore, by providing a first barrier layer 70A between the first adhesion layer 60A and the first bonding layer 40A, the first barrier layer 70A can act as a barrier, preventing the material of the first bonding layer 40A from diffusing into the driving substrate 10 during manufacturing or use, thus affecting the performance of the driving substrate 10 and improving the thermal stability and long-term reliability of the micro-light-emitting device 1.

[0050] In some examples, the first barrier layer 70A may be made of a metallic material, such as platinum (Pt). The first adhesion layer 60A may be made of a metallic material, such as titanium (Ti) and / or chromium (Cr).

[0051] In some embodiments, such as Figure 1 As shown, the aforementioned micro-light-emitting device 1 may further include at least one second adhesive layer 80A and at least one second blocking layer 90A. Furthermore, in the micro-light-emitting device 1, the at least one second adhesive layer 80A is located between the at least one light-emitting structure 20A and the at least one second bonding layer 50A, and is respectively disposed corresponding to the at least one second bonding layer 50A; the at least one second blocking layer 90A is located between the at least one second adhesive layer 80A and the at least one second bonding layer 50A, and is respectively disposed corresponding to the at least one second bonding layer 50A.

[0052] Thus, by providing a second adhesion layer 80A between the light-emitting structure 20A and the second bonding layer 50A, the second adhesion layer 80A can enhance the bonding force between the second bonding layer 50A and the light-emitting structure 20A, preventing the second bonding layer 50A from detaching or shifting during manufacturing or use. Furthermore, by providing a second barrier layer 90A between the second adhesion layer 80A and the second bonding layer 50A, the second barrier layer 90A can act as a barrier, preventing the material of the second bonding layer 50A from diffusing into the light-emitting structure 20A during manufacturing or use, thus affecting the performance of the light-emitting structure 20A and improving the thermal stability and long-term reliability of the micro-light-emitting device 1.

[0053] In some examples, the material of the second barrier layer 90A can be a metallic material, such as platinum (Pt). The material of the second adhesion layer 80A can be a metallic material, such as titanium (Ti) and / or chromium (Cr).

[0054] In the above embodiments, such as Figure 1 As shown, the number of light-emitting structures 20A included in the above-mentioned micro light-emitting device 1 can be multiple. These multiple light-emitting structures 20A can be arranged at intervals and can be arranged in an array to form a light-emitting structure array.

[0055] In the above embodiments, such as Figure 2 As shown, the aforementioned micro-light-emitting device 1 may further include a passivation layer 120. The passivation layer 120 is disposed on one side of the driving substrate 10 where at least one light-emitting structure 20A is bonded and connected, and at least covers the sidewalls of each light-emitting structure 20A, each sidewall of the first buffer adhesive layer 30A, each sidewall of the first bonding layer 40A, and each sidewall of the second bonding layer 50A, to achieve insulation treatment of the sidewalls of the light-emitting structure 20A, the first buffer adhesive layer 30A, the first bonding layer 40A, and the second bonding layer 50A, preventing short circuits or leakage current problems. In addition, the passivation layer 120 can also serve as a protective layer, effectively preventing external water and oxygen from intruding into the light-emitting structure 20A and affecting the luminous efficiency.

[0056] In some examples, the material of the passivation layer 120 may include at least one of insulating materials such as silicon oxide, silicon nitride, and aluminum oxide, and may be formed by chemical vapor deposition (CVD) or plasma-enhanced chemical vapor deposition (PECVD).

[0057] Specifically, such as Figure 2As shown, the micro light-emitting device 1 may further include an electrode layer 130, which is disposed on the side of at least one light-emitting structure 20A away from the driving substrate 10 and on the side of the passivation layer 120 away from the driving substrate 10, and is electrically connected to each light-emitting structure 20A (e.g., the first semiconductor layer 21 of each light-emitting structure 20A), thereby enabling all light-emitting structures 20A in the micro light-emitting device 1 to share the same electrode (i.e., the electrode layer 130).

[0058] Furthermore, in specific implementation, such as Figure 2 As shown, the aforementioned micro-light-emitting device 1 may further include at least one electrode contact 140, which is disposed on the side of the electrode layer 130 opposite to the at least one light-emitting structure 20A and the passivation layer 120, for electrically connecting the electrode layer 130 to an external circuit. The orthographic projection of the at least one electrode contact 140 on the driving substrate 10 is located around the orthographic projection of the at least one light-emitting structure 20A on the driving substrate 10, thereby reducing the occupation of the effective light-emitting area of ​​the light-emitting structure array and improving the aperture ratio and light output efficiency of the device.

[0059] In some examples, the electrode layer 130 can be made of a transparent and conductive material, such as indium tin oxide (ITO) or aluminum-doped zinc oxide (AZO), to ensure good conductivity and light transmittance, thereby improving the luminous efficiency and stability of the device. The electrode contact 140 can be made of a metallic material, such as at least one of titanium (Ti), gold (Au), platinum (Pt), nickel (Ni), and aluminum (Al).

[0060] In some specific embodiments, such as Figure 3 As shown, the aforementioned micro-light-emitting device 1 may further include at least one microlens 150 (e.g., a convex lens), which is disposed on the side of the electrode layer 130 opposite to the at least one light-emitting structure 20A and the passivation layer 120, and can correspond one-to-one with the at least one light-emitting structure 20A. Each microlens 150 can focus and collimate the light emitted by its corresponding light-emitting structure 20A, effectively improving the directionality of light emission and light extraction efficiency, especially significantly reducing optical crosstalk in high-density integration scenarios. The microlenses 150 and the electrode contacts 140 are spatially staggered to avoid obstruction, further optimizing the overall brightness and uniformity. In addition, the arrangement density and shape of the microlenses 150 can be customized according to the layout of the light-emitting structure 20A to achieve beam control at a specific angle and wide-angle uniform light emission.

[0061] In some specific embodiments, such as Figure 3As shown, an antireflective coating 160 or a reflective isolation layer 160 can be introduced between the electrode layer 130 and the microlens 150 to further suppress interface light loss and improve the overall photoelectric conversion efficiency of the device. The entire structure is precisely laminated with multiple thin films to ensure mechanical stability and long-term reliability, making it suitable for cutting-edge fields such as micro-displays, augmented reality, and high-precision sensing.

[0062] In this embodiment, the aforementioned micro light-emitting device 1 can be applied to any product with display function, such as electronic paper, mobile phones, tablet computers, televisions, laptops, digital photo frames, wearable devices, or navigators.

[0063] As can be seen from the above, the micro light-emitting device provided in this application includes a driving substrate, at least one first bonding layer, at least one light-emitting structure, at least one second bonding layer, and at least one buffer adhesive layer; wherein, the at least one first bonding layer is disposed on one side of the driving substrate, and the at least one second bonding layer is disposed on one side of the at least one light-emitting structure, and is respectively disposed corresponding to the at least one light-emitting structure; furthermore, the at least one second bonding layer is bonded to the at least one first bonding layer to form at least one bonding layer stack structure, so as to realize the bonding connection of the at least one light-emitting structure to the driving substrate. The driving substrate has at least one first bonding layer on one side; wherein each bonding layer stack structure consists of a correspondingly bonded second bonding layer and a first bonding layer, and a corresponding buffer adhesive layer is provided between the first bonding layer and the second bonding layer in each bonding layer stack structure; and in each bonding layer stack structure, bonding bumps are formed by local protrusions on the surface of the first bonding layer away from the driving substrate and / or the surface of the second bonding layer away from the light-emitting structure, and the buffer adhesive layer corresponding to each bonding layer stack structure fills the recessed portion around the bonding bump in each bonding layer stack structure. Thus, by optimizing the bonding layer structure design, introducing a buffer adhesive layer at the bonding interface and cooperating with the local protrusion design of the bonding bumps, the bonding bumps achieve electrical interconnection during the bonding process, while the buffer adhesive layer can fill the peripheral gaps of the bonding bumps and absorb the stress caused by thermal mismatch. This not only reduces interfacial stress concentration but also allows the buffer adhesive layer to act as a buffer during bonding, absorbing and dispersing stress. This effectively alleviates the stress concentration problem caused by the difference in thermal expansion coefficients between the substrate materials of the sapphire-based LED epitaxial wafer and the silicon-based driver IC wafer, significantly reducing the breakage rate and dark crack risk of the silicon-based driver IC wafer after bonding, and improving product yield, structural stability, and reliability. Furthermore, the localized bump design of the bonding bumps makes the bonding process more precise and controllable, further improving bonding reliability and yield, thus contributing to improved product reliability and yield.

[0064] Please see Figure 4 , Figure 4This is a schematic flowchart illustrating a method for fabricating a micro-light-emitting device according to an embodiment of this application. This embodiment is used to form a micro-light-emitting device 1 (such as...) from any of the above embodiments. Figures 1 to 3 Taking the example shown below, the fabrication method can be illustrated as follows: Step S11: Provide a driving substrate 10 and a light-emitting epitaxial wafer 200, wherein the light-emitting epitaxial wafer 200 includes a substrate 201 and a light-emitting stack 20 (e.g., ...) disposed on one side of the substrate 201. Figure 5 and Figure 6 (As shown).

[0065] In this embodiment, as Figure 6 As shown, in the light-emitting epitaxial wafer 200, the substrate 201 may include a substrate 2011, which is used to support the film structure located thereon, and may be a sapphire substrate, a silicon substrate or a silicon carbide substrate, etc. In some examples, the substrate 2011 may specifically be a sapphire substrate.

[0066] Specifically, such as Figure 6 As shown, in the light-emitting epitaxial wafer 200, the substrate 201 may further include a buffer layer 2012, which is disposed on one side of the substrate 2011, and the aforementioned light-emitting stack 20 is disposed on the side of the buffer layer 2012 facing away from the substrate 2011. The material of the buffer layer 2012 may include at least one of the following buffer materials: gallium nitride, indium nitride, indium gallium nitride, and aluminum indium gallium nitride. In some examples, the buffer layer 2012 may specifically be a gallium nitride (GaN) layer.

[0067] Specifically, such as Figure 6 As shown, in the light-emitting epitaxial wafer 200, the light-emitting stack 20 may include a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 sequentially stacked in a direction away from the substrate 201. The light-emitting layer 22 may be a quantum well layer, for example, an indium gallium nitride (IGaN) quantum well layer, or an IGaN / GaN multi-quantum well layer. The first semiconductor layer 21 and the second semiconductor layer 23 have different polarities. Specifically, the first semiconductor layer 21 may be either an N-type semiconductor layer or a P-type semiconductor layer, and the second semiconductor layer 23 may be either an N-type semiconductor layer or a P-type semiconductor layer. Specifically, the N-type semiconductor layer may be an N-type gallium nitride layer or an N-type gallium arsenide layer, and the P-type semiconductor layer may be a P-type gallium nitride layer or a P-type aluminum gallium nitride layer.

[0068] Furthermore, in specific implementation, such as Figure 6 As shown, a buffer layer 2012 can be formed on one side of the substrate 2011, and then a first semiconductor layer 21, a light-emitting layer 22, and a second semiconductor layer 23 can be formed sequentially on the side of the buffer layer 2012 away from the substrate 2011 to obtain the above-mentioned light-emitting epitaxial wafer 200.

[0069] Step S12: A first bonding layer 40 is formed on one side of the driving substrate 10, and a second bonding layer 50 is formed on the side of the light-emitting stack 20 facing away from the substrate 201; wherein, the surface of the first bonding layer 40 facing away from the driving substrate 10 is the first bonding surface F1, and the surface of the second bonding layer 50 facing away from the light-emitting stack 20 is the second bonding surface F2; and, the first bonding surface F1 and / or the second bonding surface F2 respectively have at least one bonding bump 401 / 501 protruding at at least one designated position (e.g., Figure 7 and Figure 8 (As shown).

[0070] In some embodiments, such as Figure 5 and Figure 7 As shown, the driving substrate 10 may include at least one driving electrode 11 disposed on one side of the driving substrate 10. The first bonding layer 40 is specifically formed on the side of the driving substrate 10 where the at least one driving electrode 11 is disposed, and is electrically connected to each driving electrode 11. Furthermore, the first bonding surface F1 of the first bonding layer 40 may have at least one first bonding bump 401 protruding from the position corresponding to the at least one driving electrode 11, so that the first bonding surface F1 has at least one bonding bump 401 protruding from the at least one designated position. Each first bonding bump 401 may correspond to one driving electrode 11 and is located directly above its corresponding driving electrode 11.

[0071] In some specific embodiments, such as Figure 5 and Figure 7 As shown, before forming the first bonding layer 40 on one side of the driving substrate 10, the fabrication method of the aforementioned micro-light-emitting device 1 may further include: sequentially forming a first adhesion layer 60 and a first barrier layer 70 on one side of the driving substrate 10. Accordingly, the first bonding layer 40 may specifically be formed on the side of the first barrier layer 70 facing away from the first adhesion layer 60. Furthermore, in a specific implementation, a first metal material layer, a second metal material layer, and a third metal material layer may be sequentially deposited on one side of the driving substrate 10 (for example, the side where at least one driving electrode 11 is provided) by an electron beam evaporation process. Then, at least one first bonding bump 401 may be formed by etching the surface of the third metal material layer facing away from the second metal material layer by an etching process (for example, an ion beam etching process), resulting in the first adhesion layer 60, the first barrier layer 70, and the first bonding layer 40 being sequentially stacked in a direction away from the driving substrate 10. The first adhesion layer 60 is the first metal material layer, the first barrier layer 70 is the second metal material layer, and the first bonding layer 40 is the etched third metal material layer.

[0072] In some embodiments, such as Figure 6 and Figure 8 As shown, the aforementioned light-emitting stack 20 may have at least one light-emitting region C1. The second bonding surface F2 of the aforementioned second bonding layer 50 may have at least one second bonding bump 501 protruding from the position corresponding to the at least one light-emitting region C1, thereby achieving that the second bonding surface F2 has at least one bonding bump 501 protruding from the at least one designated position. Each second bonding bump 501 may correspond to one light-emitting region C1 and is located directly above its corresponding light-emitting region C1. Specifically, as... Figure 6 and Figure 8 As shown, the above-mentioned light-emitting stack 20 may also have a non-light-emitting region C2, which is arranged around each light-emitting region C1 and separates each light-emitting region C1 from other light-emitting regions C1 located around it.

[0073] In some specific embodiments, such as Figure 6 and Figure 8 As shown, before forming the second bonding layer 50 on the side of the light-emitting stack 20 away from the substrate 201, the fabrication method of the aforementioned micro-light-emitting device 1 may further include: sequentially forming a second adhesion layer 80 and a second barrier layer 90 on the side of the light-emitting stack 20 away from the substrate 201. Accordingly, the second bonding layer 50 may specifically be formed on the side of the second barrier layer 90 away from the second adhesion layer 80. Furthermore, in a specific implementation, a fourth metal material layer, a fifth metal material layer, and a sixth metal material layer may be sequentially deposited on the side of the light-emitting stack 20 away from the substrate 201 using an electron beam evaporation process. Then, at least one second bonding bump 501 may be formed by etching the surface of the sixth metal material layer away from the fifth metal material layer using an etching process (e.g., ion beam etching process), resulting in a second adhesion layer 80, a second barrier layer 90, and a second bonding layer 50 sequentially stacked in a direction away from the light-emitting stack 20. Among them, the second adhesion layer 80 is the fourth metal material layer, the second barrier layer 90 is the fifth metal material layer, and the second bonding layer 50 is the etched sixth metal material layer.

[0074] Step S13: Form a buffer adhesive layer 30 (e.g., on the first bonding surface F1 and / or the second bonding surface F2) Figure 9 (As shown).

[0075] Specifically, such as Figure 9 As shown, a buffer adhesive layer 30 can be formed on the first bonding surface F1 without forming another buffer adhesive layer on the second bonding surface F2; or, a buffer adhesive layer 30 can be formed on the second bonding surface F2 without forming another buffer adhesive layer on the first bonding surface F1; or, a buffer adhesive layer 30 can be formed on both the first bonding surface F1 and the second bonding surface F2.

[0076] Step S14: Bond the first bonding surface F1 to the second bonding surface F2 to form a bonding structure. During the bonding process, the buffer adhesive layer 30 is squeezed to the periphery of the bonding bumps 401 / 501 by the bonding bumps 401 / 501 (e.g., Figure 10 and Figure 11 (As shown).

[0077] In some embodiments, such as Figure 9 As shown, step S13 may include: coating a layer of buffer adhesive on the first bonding surface F1 and removing the solvent from the coated buffer adhesive to obtain a buffer adhesive layer 30 in a pre-cured state.

[0078] Specifically, a buffer adhesive film can be vacuum-laminated to uniformly cover the first bonding surface F1. Then, the solvent in the buffer adhesive film is evaporated and removed by heating, resulting in a pre-cured buffer adhesive layer 30. This vacuum lamination process, combined with a precise temperature control profile, ensures a tight bond between the buffer adhesive layer 30 and the first bonding surface F1, providing a stable stress buffer foundation for the subsequent bonding process.

[0079] Furthermore, in step S14 above, during the bonding process of the first bonding surface F1 and the second bonding surface F2, the pre-cured buffer adhesive layer 30 undergoes micro-flow under the pressure of the bonding bumps 401 / 501, extending towards the bonding bumps 401 / 501 and filling the gaps in the bonding interface, forming a buffer structure around the bonding bumps 401 / 501. This effectively releases local stress during the bonding process and improves the reliability of the interface bonding. This micro-flow characteristic allows the buffer adhesive layer 30 to adapt to the morphological differences of different bonding bumps 401 / 501, ensuring the uniformity of stress distribution across the entire bonding surface F1 / F2. After bonding is completed, the buffer adhesive layer 30 and the bonding bumps 401 / 501 together constitute a composite stress buffer structure. The bonding bumps 401 / 501 bear the main vertical stress, while the buffer adhesive layer 30 disperses the horizontal shear stress. The synergistic effect of the two significantly reduces the risk of bonding interface failure.

[0080] Furthermore, during the bonding process, the aforementioned buffer adhesive layer 30 transitions from a pre-cured state to a fully cured state. Specifically, the pre-cured buffer adhesive layer 30 further cures under the bonding temperature, enhancing interfacial adhesion strength and ultimately achieving full curing. Moreover, after full curing, the pre-cured buffer adhesive layer 30 possesses a suitable elastic modulus, preventing excessive deformation of the bonding bumps 401 / 501 and buffering thermal mismatch stress during subsequent device operation, thereby significantly improving the yield and long-term stability of the micro-light-emitting device 1.

[0081] In some specific embodiments, such as Figure 9As shown, step S13 may include forming a buffer adhesive layer 30 on the first bonding surface F1. Furthermore, after forming the buffer adhesive layer 30 on the first bonding surface F1 and before step S14, the fabrication method of the micro-light-emitting device 1 may further include forming a conductive adhesive layer 110 on the surface of the buffer adhesive layer 30 facing away from the second bonding surface F2. Specifically, as... Figure 9 As shown, a conductive adhesive film can be uniformly applied to the surface of the buffer adhesive layer 30 facing away from the second bonding surface F2 using a vacuum bonding method. Then, the solvent in the conductive adhesive film is evaporated and removed by heating, resulting in a pre-cured conductive adhesive layer 110. This vacuum bonding process, combined with a precise temperature control profile, ensures a tight bond between the conductive adhesive layer 110 and the buffer adhesive layer 30, providing a stable stress buffer for the subsequent bonding process.

[0082] Furthermore, in step S14 above, during the bonding process between the first bonding surface F1 and the second bonding surface F2, the conductive adhesive layer 110 is compressed by the bonding bumps 401 / 501, electrically connecting the first bonding layer 40 and the second bonding layer 50. Specifically, the conductive adhesive layer 110 undergoes plastic deformation under the compression of the bonding bumps 401 / 501, forming a continuous conductive path. Simultaneously, its pre-cured state transforms into complete curing under the bonding temperature, ensuring the long-term stability of the electrical connection. This design allows the conductive adhesive layer 110 to withstand the mechanical stress during the bonding process while maintaining excellent conductivity, avoiding electromigration problems that may be caused by traditional metal bonding. In addition, the composite structure of the conductive adhesive layer 110 and the buffer adhesive layer 30 forms a gradient stress buffering system. The conductive adhesive layer 110 is responsible for the vertical electrical connection and initial stress dispersion, while the buffer adhesive layer 30 bears the horizontal shear stress buffering. The synergistic effect of the two significantly improves the mechanical reliability and electrical performance of the bonding interface.

[0083] In some specific embodiments, such as Figure 7 and Figure 8 As shown, the first bonding surface F1 has at least one first bonding bump 401 protruding at the position corresponding to the at least one driving electrode 11, and the second bonding surface F2 of the second bonding layer 50 has at least one second bonding bump 501 protruding at the position corresponding to the at least one light-emitting region C1. Furthermore, each second bonding bump 501 corresponds to one first bonding bump 401.

[0084] Accordingly, such as Figure 10 and Figure 11As shown, the bonding structure formed by bonding the first bonding surface F1 and the second bonding surface F2 can include bonding the second bonding bump 501 to the corresponding first bonding bump 401. Specifically, the second bonding bump 501 and the corresponding first bonding bump 401 can be aligned, and then appropriate pressure and temperature can be applied. During the bonding process, the second bonding bump 501 and the corresponding first bonding bump 401 will jointly compress the buffer adhesive layer 30 located between them, causing micro-flow in the portion of the buffer adhesive layer 30 located between the second bonding bump 501 and the first bonding bump 401, filling the recessed areas around the first bonding bump 401 and the second bonding bump 501, and simultaneously triggering its complete curing reaction.

[0085] Furthermore, in the above embodiment where the fabrication method of the aforementioned micro-light-emitting device 1 further includes the step of forming a conductive adhesive layer 110 on the surface of the buffer adhesive layer 30 facing away from the second bonding surface F2, in step S14, during the bonding process between the first bonding surface F1 and the second bonding surface F2, the conductive adhesive layer 110 is squeezed by the first bonding bump 401 and the second bonding bump 501, thereby electrically connecting the second bonding bump 501 to the corresponding first bonding bump 401. Specifically, during the bonding process, the conductive adhesive layer 110 becomes further compacted under the pressure of the second bonding bump 501 and the first bonding bump 401, simultaneously triggering its complete curing reaction to form a stable and low-resistance electrical connection path.

[0086] It should be noted that, in this embodiment, this point-to-point bonding method ensures that a stable and reliable connection is formed between each corresponding pair of bonding bumps, thereby guaranteeing the integrity and stability of the entire bonding structure. Furthermore, since each second bonding bump 501 corresponds to a first bonding bump 401, the stress distribution during the bonding process is more uniform, reducing the risk of bonding failure due to stress concentration and improving the fabrication quality and reliability of the micro-light-emitting device 1.

[0087] Furthermore, after bonding is completed, the aforementioned buffer adhesive layer 30 can fill the recessed areas around the first bonding bump 401 and the second bonding bump 501, either alone or together with the aforementioned conductive adhesive layer 110, and completely fill the gap between the recessed areas of the first bonding surface F1 and the second bonding surface F2, thereby effectively avoiding interface delamination and stress concentration, and further improving the sealing performance and long-term working stability of the bonding structure.

[0088] Step S15: Remove the substrate 201 of the light-emitting epitaxial wafer 200 in the bonding structure to expose the light-emitting stack 20 (e.g., Figure 12 (As shown).

[0089] Specifically, such as Figure 11 and Figure 12As shown, after bonding the first bonding surface F1 and the second bonding surface F2 to form a bonding structure, a laser lift-off process can be used to remove the substrate 201 of the light-emitting epitaxial wafer 200 in the bonding structure, thereby exposing the surface of the light-emitting stack 20 in the bonding structure that contacts the substrate 201, so as to facilitate the execution of subsequent process steps.

[0090] Furthermore, in the above embodiment where the substrate 201 of the light-emitting epitaxial wafer 200 includes a substrate 2011 and a buffer layer 2012, a laser lift-off process can be used first to remove the substrate 2011 of the light-emitting epitaxial wafer 200 in the bonding structure, and then the buffer layer 2012 of the light-emitting epitaxial wafer 200 in the bonding structure can be decomposed and removed, thereby completing the removal of the substrate 201 of the light-emitting epitaxial wafer 200 in the bonding structure.

[0091] It should be noted that, compared to existing bonding processes where silicon-based driver IC wafers are prone to breakage and dark cracks after bonding, affecting product yield, this embodiment optimizes the structural design of the bonding layers 40 / 50. A buffer adhesive layer 30 is introduced at the bonding interface, along with the localized protrusion design of the bonding bumps 401 / 501. The buffer adhesive layer 30 acts as a buffer during bonding, absorbing and dispersing stress. This effectively alleviates the stress concentration problem caused by the difference in thermal expansion coefficients between the sapphire-based LED epitaxial wafer and the silicon-based driver IC wafer's substrate materials. Therefore, during the laser lift-off of the sapphire substrate from the sapphire-based LED epitaxial wafer, damage to the epitaxial light-emitting layers in the sapphire-based LED epitaxial wafer can be effectively reduced, improving the lift-off yield.

[0092] Step S16: Based on the bonding structure after removing substrate 201, a micro light-emitting device 1 is fabricated (e.g., Figures 1 to 3 (As shown).

[0093] In some embodiments, step S16 may specifically include: Step S161: On the side of the light-emitting stack 20 exposed after removing the substrate 201 that faces away from the driving substrate 10, a groove 202 is formed that extends through the driving substrate 10. The orthographic projection of the groove 202 on the driving substrate 10 surrounds the orthographic projection of each light-emitting region C1 on the driving substrate 10, so as to divide all the film layer structures on the driving substrate 10 as a whole into at least one light-emitting unit (e.g., Figure 1 (As shown).

[0094] It should be noted that, as Figure 1As shown, after the groove 202 divides all the film layer structures on the driving substrate 10 into at least one light-emitting unit as a whole, the first bonding layer 40A in each light-emitting unit corresponds to a first bonding layer 40A in the above-described micro-light-emitting device embodiment, the buffer adhesive layer 30A in each light-emitting unit corresponds to a buffer adhesive layer 30A in the above-described micro-light-emitting device embodiment, the second bonding layer 50A in each light-emitting unit corresponds to a second bonding layer 50A in the above-described micro-light-emitting device embodiment, and the light-emitting stack 20A in each light-emitting unit corresponds to a light-emitting structure 20A in the above-described micro-light-emitting device embodiment. The conductive adhesive layer 110A in each light-emitting unit corresponds to a conductive adhesive layer 110A in the above-described micro light-emitting device embodiment. The first adhesive layer 60A in each light-emitting unit corresponds to a first adhesive layer 60A in the above-described micro light-emitting device embodiment. The first blocking layer 70A in each light-emitting unit corresponds to a first blocking layer 70A in the above-described micro light-emitting device embodiment. The second adhesive layer 80A in each light-emitting unit corresponds to a second adhesive layer 80A in the above-described micro light-emitting device embodiment. The second blocking layer 90A in each light-emitting unit corresponds to a second blocking layer 90A in the above-described micro light-emitting device embodiment.

[0095] Specifically, such as Figure 1 As shown, after removing the substrate 201 of the light-emitting epitaxial wafer 200 in the bonding structure and exposing the light-emitting stack 20, a groove 202 extending through the driving substrate 10 can be formed on the side of the light-emitting stack 20 away from the driving substrate 10 by an etching process.

[0096] Step S162: Form a passivation layer 120, the passivation layer 120 at least covering the sidewall of each light-emitting unit (e.g., Figure 2 (As shown).

[0097] Specifically, such as Figure 1 and Figure 2 As shown, after forming the groove 202, a passivation layer 120 can be formed on the side of the driving substrate 10 where at least one light-emitting unit is provided by a deposition process. The passivation layer 120 fills the groove 202, and the filling thickness of the passivation layer 120 should ensure that it completely covers the sidewalls of the light-emitting layer 22 of the light-emitting stack 20A in the light-emitting unit, so that the sidewalls of the light-emitting layer 22 are completely insulated, thereby protecting the light-emitting layer 22 and preventing the increase of non-radiative recombination on the sidewalls of the light-emitting layer 22. For example, as Figure 10 and Figure 11 As shown, the passivation layer 120 can completely fill the groove 202, and the surface of the passivation layer 13 facing away from the driving substrate 10 can be a flat surface, and can be located in the same plane or substantially in the same plane as the surface of the light-emitting stack 20A in the light-emitting unit facing away from the driving substrate 10, so as to facilitate the smooth implementation of subsequent processes.

[0098] Step S163: An electrode layer 130 is formed on the side of the passivation layer 120 facing away from the driving substrate 10 and on the side of at least one light-emitting unit facing away from the driving substrate 10. The electrode layer 130 is electrically connected to the light-emitting stack 20A in each light-emitting unit (e.g., Figure 2 (As shown).

[0099] Specifically, such as Figure 2 As shown, an electrode layer 130 can be formed on the side of the passivation layer 120 facing away from the driving substrate 10 and on the side of the at least one light-emitting unit facing away from the driving substrate 10 through a deposition process. The electrode layer 130 can be made of a light-transmitting and conductive material, such as indium tin oxide (ITO) or aluminum-doped zinc oxide (AZO), to ensure good conductivity and light transmittance, thereby improving the luminous efficiency and stability of the device.

[0100] In some embodiments, after step S163, step S16 may further include: Step S164: At least one electrode contact 140 is formed on the side of the electrode layer 130 opposite to the at least one light-emitting unit and the passivation layer 120 (e.g., Figure 2 (As shown).

[0101] The electrode contact 140 is used to electrically connect the electrode layer 130 to an external circuit.

[0102] In some embodiments, after step S163, step S16 may further include: Step S165: At least one microlens 150 is formed on the side of the electrode layer 130 opposite to the at least one light-emitting unit and the passivation layer 120 (e.g., Figure 3 (As shown).

[0103] The at least one microlens 150 corresponds one-to-one with the light-emitting stack 20A in the at least one light-emitting unit.

[0104] It should be noted that the specific structure of the micro light-emitting device 1 in this embodiment can be referred to the specific implementation method in the above embodiment of the micro light-emitting device, so it will not be repeated here.

[0105] As can be seen from the above, the method for fabricating a micro light-emitting device provided in this application embodiment involves providing a driving substrate and a light-emitting epitaxial wafer, wherein the light-emitting epitaxial wafer includes a substrate and a light-emitting stack disposed on one side of the substrate, then forming a first bonding layer on one side of the driving substrate, and forming a second bonding layer on the side of the light-emitting stack facing away from the substrate, wherein the surface of the first bonding layer facing away from the driving substrate is a first bonding surface, the surface of the second bonding layer facing away from the light-emitting stack is a second bonding surface, and at least one bonding bump is formed on the first bonding surface and / or the second bonding surface at at least one designated position, and then the first bonding surface and / or the second bonding surface are respectively raised to form at least one bonding bump. Alternatively, a buffer adhesive layer can be formed on the second bonding surface, and then the first and second bonding surfaces are bonded to form a bonding structure. During the bonding process, the buffer adhesive layer is squeezed to the periphery of the bonding bumps. Afterward, the substrate of the light-emitting epitaxial wafer in the bonding structure is removed, exposing the light-emitting stack. Then, a micro-light-emitting device is fabricated based on the bonding structure after removing the substrate. In this way, by optimizing the bonding layer structure design, introducing a buffer adhesive layer at the bonding interface, and cooperating with the local bump design of the bonding bumps, the bonding bumps achieve electrical interconnection during the bonding process, while the buffer adhesive layer can fill the peripheral gaps of the bonding bumps and absorb the stress caused by thermal mismatch. This not only reduces the stress concentration at the interface, but also allows the buffer adhesive layer to play a buffering role during the bonding process, absorbing and dispersing stress. This effectively alleviates the stress concentration problem caused by the difference in the thermal expansion coefficients of the substrate materials of the sapphire-based LED epitaxial wafer and the silicon-based driver IC wafer, significantly reducing the breakage rate and dark crack risk of the silicon-based driver IC wafer after bonding, and improving the product yield, structural stability, and reliability. In addition, the local bump design of the bonding bumps makes the bonding process more precise and controllable, further improving the reliability and yield of the bonding, thus helping to improve the reliability and yield of the product.

[0106] It should be noted that, unless otherwise specified, the embodiments and features described in this application can be combined with each other. The features, structures, or characteristics described above can be combined in any suitable manner in one or more embodiments.

[0107] The above description is merely a preferred embodiment of this application and is not intended to limit this application. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A miniature light-emitting device, characterized in that, include: A driving substrate and at least one first bonding layer, wherein the at least one first bonding layer is disposed on one side of the driving substrate; The system includes at least one light-emitting structure and at least one second bonding layer. The at least one second bonding layer is disposed on one side of the at least one light-emitting structure and is respectively disposed corresponding to the at least one light-emitting structure. The at least one second bonding layer is correspondingly bonded to the at least one first bonding layer to form at least one bonding layer stack structure, so as to realize that the at least one light-emitting structure is bonded to the side of the driving substrate where the at least one first bonding layer is disposed. Each bonding layer stack structure is composed of a correspondingly bonded second bonding layer and a first bonding layer. At least one buffer adhesive layer, and a corresponding buffer adhesive layer is provided between the first bonding layer and the second bonding layer in each of the bonding layer stack structures; Furthermore, in each of the bonding layer stack structures, the surface of the first bonding layer facing away from the driving substrate and / or the surface of the second bonding layer facing away from the light-emitting structure are partially raised to form bonding bumps, and the buffer adhesive layer corresponding to each of the bonding layer stack structures fills the recessed portion around the bonding bumps in each of the bonding layer stack structures.

2. The micro light-emitting device according to claim 1, characterized in that, In each of the bonding layer stack structures, the first bonding layer has a first bonding bump formed on a partial protrusion on the surface away from the driving substrate, and the second bonding layer has a second bonding bump formed on a partial protrusion on the surface away from the light-emitting structure. The first bonding bump and the second bonding bump are bonded together, and there is a facing area between the first bonding bump and the second bonding bump. Furthermore, the buffer adhesive layer corresponding to each of the bonding layer stack structures is located outside the opposing region between the first bonding bump and the second bonding bump in each of the bonding layer stack structures.

3. The micro light-emitting device according to claim 2, characterized in that, In each of the bonding layer stack structures, the first bonding bump is formed by protruding from the central region of the surface of the first bonding layer away from the driving substrate, and the second bonding bump is formed by protruding from the central region of the surface of the second bonding layer away from the light-emitting structure. The surface of the first bonding bump away from the driving substrate and the surface of the second bonding bump away from the light-emitting structure have the same shape and size.

4. The micro light-emitting device according to claim 1, characterized in that, The micro light-emitting device also includes: At least one conductive adhesive layer is provided, and a corresponding conductive adhesive layer is provided between the first bonding layer and the second bonding layer in each bonding layer stack structure, and the conductive adhesive layer corresponding to each bonding layer stack structure electrically connects the first bonding layer and the second bonding layer in each bonding layer stack structure.

5. The micro light-emitting device according to claim 4, characterized in that, The conductive adhesive layer and the buffer adhesive layer corresponding to each of the bonding layer stacks together completely fill the gap between the first bonding layer and the second bonding layer in each of the bonding layer stacks.

6. The micro light-emitting device according to claim 1, characterized in that, The micro light-emitting device also includes: At least one first adhesive layer and at least one first barrier layer, wherein the at least one first adhesive layer is located between the driving substrate and the at least one first bonding layer, and is respectively disposed corresponding to the at least one first bonding layer; the at least one first barrier layer is located between the at least one first adhesive layer and the at least one first bonding layer, and is respectively disposed corresponding to the at least one first bonding layer. At least one second adhesive layer and at least one second blocking layer, wherein the at least one second adhesive layer is located between the at least one light-emitting structure and the at least one second bonding layer, and is respectively disposed corresponding to the at least one second bonding layer; the at least one second blocking layer is located between the at least one second adhesive layer and the at least one second bonding layer, and is respectively disposed corresponding to the at least one second bonding layer.

7. A method for fabricating a micro light-emitting device, characterized in that, include: A driving substrate and a light-emitting epitaxial wafer are provided, wherein the light-emitting epitaxial wafer includes a substrate and a light-emitting stack disposed on one side of the substrate; A first bonding layer is formed on one side of the driving substrate, and a second bonding layer is formed on the side of the light-emitting stack facing away from the substrate; wherein, the surface of the first bonding layer facing away from the driving substrate is a first bonding surface, and the surface of the second bonding layer facing away from the light-emitting stack is a second bonding surface; and, the first bonding surface and / or the second bonding surface each have at least one bonding bump protruding at at least one designated position. A buffer adhesive layer is formed on the first bonding surface and / or the second bonding surface; The first bonding surface and the second bonding surface are bonded to form a bonding structure. During the bonding process, the buffer adhesive layer is squeezed to the periphery of the bonding bump by the bonding bump. Remove the substrate of the light-emitting epitaxial wafer in the bonding structure to expose the light-emitting stack; Micro-light-emitting devices were fabricated based on the bonding structure after substrate removal.

8. The method for fabricating a micro light-emitting device according to claim 7, characterized in that, The driving substrate includes at least one driving electrode disposed on one side of the driving substrate, and the first bonding surface has at least one first bonding bump formed at the position corresponding to the at least one driving electrode. The light-emitting stack has at least one light-emitting region, and the second bonding surface has at least one second bonding bump at a position corresponding to the at least one light-emitting region. Furthermore, each of the second bonding bumps corresponds to one of the first bonding bumps; The step of bonding the first bonding surface and the second bonding surface to form a bonding structure includes: The second bonding bump is bonded to the corresponding first bonding bump to form a bonding structure.

9. The method for fabricating a micro light-emitting device according to claim 8, characterized in that, The formation of a buffer adhesive layer on the first bonding surface and / or the second bonding surface includes: A buffer adhesive is coated on the first bonding surface, and the solvent in the coated buffer adhesive is removed to obtain a buffer adhesive layer in a pre-cured state; and during the bonding process, the buffer adhesive layer changes from a pre-cured state to a fully cured state. After forming a buffer adhesive layer on the first bonding surface and / or the second bonding surface, and before bonding the first bonding surface and the second bonding surface to form a bonding structure, the method further includes: A conductive adhesive layer is formed on the surface of the buffer adhesive layer that is away from the second bonding surface; and during the bonding process, the conductive adhesive layer is squeezed by the first bonding bump and the second bonding bump to electrically connect the first bonding bump to the corresponding second bonding bump.

10. The method for fabricating a micro light-emitting device according to claim 7, characterized in that, The micro-light-emitting device fabricated based on the bonding structure after substrate removal includes: On the side of the light-emitting stack exposed by removing the substrate that is away from the driving substrate, a groove is formed that extends through the driving substrate. The orthographic projection of the groove on the driving substrate is arranged around the orthographic projection of each light-emitting region on the driving substrate, so as to divide all the film layer structures on the driving substrate as a whole into at least one light-emitting unit. A passivation layer is formed, the passivation layer at least covering the sidewall of each of the light-emitting units; An electrode layer is formed on the side of the passivation layer opposite to the driving substrate and on the side of the at least one light-emitting unit opposite to the driving substrate, and the electrode layer is electrically connected to the light-emitting stack in each of the light-emitting units.

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