Light-emitting substrate, display substrate, preparation method therefor, and display device

Abstract

Provided are a light-emitting substrate, a display substrate and a preparation method therefor, and a display device. The light-emitting substrate comprises: a first substrate; a bonding layer located on one side of the first substrate, at least part of the area of the bonding layer away from the first substrate comprising a plurality of grooves; an optical adhesive layer located on the side of the bonding layer away from the first substrate, the optical adhesive layer comprising a plurality of isolation portions, the plurality of isolation portions respectively filling the plurality of grooves; and a light-emitting layer located on the side of the optical adhesive layer away from the first substrate, the light-emitting layer comprising a plurality of light-emitting elements arranged in an array, wherein the orthographic projections of the plurality of light-emitting elements on the first substrate respectively at least partially overlap the orthographic projections of the plurality of isolation portions on the first substrate; and the shear strength between the material of the light-emitting layer and the material of the bonding layer is greater than the shear strength between the material of the light-emitting layer and the material of the optical adhesive layer.

Description

Light-emitting substrate, display substrate, preparation method thereof and display device Technical Field

[0001] This disclosure relates to the field of display technology, and in particular to a light-emitting substrate, a display substrate, a method for preparing the same, and a display device. Background Technology

[0002] Micro LED (micro light emitting diode, or uLED) chips are a new type of LED chip with advantages such as high brightness, high luminous efficiency, and low power consumption, and have broad application prospects in the display industry. Micro LED chips are typically formed on epitaxial substrates such as sapphire or silicon wafers, and their use requires transfer from the epitaxial substrate to the target substrate. Currently, mass transfer techniques are mainly used to transfer Micro LED chips to the target substrate, such as stamp-type and fluid self-alignment methods. However, these methods result in small transfer areas per transfer, requiring multiple transfers, leading to low transfer efficiency and high cost. Therefore, how to efficiently and cost-effectively transfer Micro LED chips to the target substrate is one of the important research topics for those skilled in the art.

[0003] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure, and therefore may include information that does not constitute prior art known to those skilled in the art. Summary of the Invention

[0004] In one aspect, a light-emitting substrate is provided, comprising:

[0005] First substrate;

[0006] A bonding layer located on one side of the first substrate, wherein at least a portion of the bonding layer on the side away from the first substrate includes a plurality of grooves;

[0007] An optical adhesive layer, located on the side of the bonding layer away from the first substrate, the optical adhesive layer including a plurality of isolation portions, the plurality of isolation portions respectively filling the plurality of grooves; and

[0008] A light-emitting layer is located on the side of the optical adhesive layer away from the first substrate, and the light-emitting layer includes a plurality of light-emitting elements arranged in an array.

[0009] Wherein, the orthographic projections of the plurality of light-emitting elements on the first substrate at least partially overlap with the orthographic projections of the plurality of insulating portions on the first substrate; and

[0010] The shear strength between the material of the light-emitting layer and the material of the bonding layer is greater than the shear strength between the material of the light-emitting layer and the material of the optical adhesive layer.

[0011] According to some exemplary embodiments, the orthographic projection of the optical adhesive layer on the first substrate falls within the orthographic projection of the plurality of grooves on the first substrate; and / or,

[0012] The optical adhesive layer and the bonding layer form a planarized surface on the surface away from the first substrate.

[0013] According to some exemplary embodiments, the light-emitting layer includes a first functional layer located on the side of the light-emitting layer closest to the optical adhesive layer.

[0014] Wherein, the first functional layer comprises a conductive material or an inorganic semiconductor material; and / or,

[0015] The shear strength between the material of the first functional layer and the material of the bonding layer is greater than or equal to 10 MPa.

[0016] According to some exemplary embodiments, at least a portion of the isolation portion's orthographic projection on the first substrate completely overlaps with at least a portion of the light-emitting element's orthographic projection on the first substrate; and

[0017] The light-emitting layer is in direct contact with the optical adhesive layer.

[0018] According to some exemplary embodiments, at least a portion of the isolation portion's orthographic projection on the first substrate falls within the orthographic projection of at least a portion of the light-emitting element on the first substrate; and

[0019] A portion of the light-emitting layer is in direct contact with the optical adhesive layer, and another portion of the light-emitting layer is in direct contact with the bonding layer.

[0020] According to some exemplary embodiments, at least one of the light-emitting elements includes an output electrode located on a surface of the light-emitting element away from the first substrate.

[0021] According to some exemplary embodiments, the first substrate includes a glass substrate; and / or,

[0022] The bonding temperature of the bonding layer is less than or equal to 280°C.

[0023] According to some exemplary embodiments, the bonding layer includes a first sub-bonding layer, wherein, in the light emission direction of the light-emitting substrate, the height of the first sub-bonding layer is greater than the height of the optical adhesive layer; and / or,

[0024] In the light-emitting direction of the light-emitting substrate, the height of the optical adhesive layer is in the range of 1 micrometer to 10 micrometers.

[0025] According to some exemplary embodiments, the material of the first sub-bonding layer includes gold, silver, and tin metals or metal alloys; and

[0026] The bonding layer further includes a second sub-bonding layer, the material of which includes gold, silver and tin metals or metal alloys.

[0027] In another aspect, a display substrate is provided, comprising:

[0028] Second substrate;

[0029] A pad layer, the pad layer being located on one side of the second substrate, the pad layer comprising a plurality of pads arranged in an array;

[0030] A light-emitting layer is located on the side of the pad layer away from the second substrate. The light-emitting layer includes a plurality of light-emitting elements arranged in an array, and at least a portion of the pads are electrically connected to at least a portion of the light-emitting elements.

[0031] An optical adhesive layer, located on the side of the light-emitting layer away from the second substrate, the optical adhesive layer including a plurality of insulating portions and a plurality of first openings located between the plurality of insulating portions; and

[0032] A bonding layer, at least a portion of which fills the plurality of first openings.

[0033] Wherein, the shear strength between the material of the light-emitting layer and the material of the bonding layer is greater than the shear strength between the material of the light-emitting layer and the material of the optical adhesive layer.

[0034] According to some exemplary embodiments, in the light-emitting direction of the display substrate, the height of the bonding layer is equal to the height of the optical adhesive layer; and

[0035] The bonding layer includes a plurality of light-shielding portions, and the orthographic projection of the light-shielding portions on the second substrate is located in the orthographic projection of the plurality of first openings on the second substrate.

[0036] According to some exemplary embodiments, the surface of the optical adhesive layer near the second substrate and the surface of the bonding layer near the second substrate form a planarized surface.

[0037] According to some exemplary embodiments, the display substrate further includes an insulating layer located between the pad layer and the light-emitting layer, the insulating layer including a plurality of second openings, each of the plurality of second openings exposing at least a portion of the surface of the plurality of pads away from the second substrate.

[0038] In another aspect, a display device is provided, comprising a light-emitting substrate as described in any of the preceding claims or a display substrate as described in any of the preceding claims.

[0039] In another aspect, a method for preparing a light-emitting substrate is provided, comprising:

[0040] Provide epitaxial substrates;

[0041] An epitaxial layer is formed on the epitaxial substrate;

[0042] An optical adhesive material layer is formed on the side of the epitaxial layer away from the epitaxial substrate, and a patterning process is performed to form the optical adhesive layer, wherein the optical adhesive layer includes a plurality of isolation portions and a plurality of first openings located between the plurality of isolation portions;

[0043] A first sub-bonding layer is formed on the side of the optical adhesive layer away from the epitaxial substrate. The first sub-bonding layer fills a plurality of first openings in the optical adhesive layer to form a first portion comprising the epitaxial substrate, the epitaxial layer, the optical adhesive layer, and the first sub-bonding layer.

[0044] Provide a first substrate;

[0045] A first adhesive layer is formed on one side of the first substrate;

[0046] A second sub-bonding layer is formed on the side of the first adhesive layer away from the first substrate to form a second portion comprising the first substrate, the first adhesive layer and the second sub-bonding layer;

[0047] The first sub-bonding layer in the first part and the second sub-bonding layer in the second part are bonded together, wherein the first sub-bonding layer and the second sub-bonding layer form a bonding layer.

[0048] According to some exemplary embodiments, the method further includes: stripping the epitaxial substrate.

[0049] According to some exemplary embodiments, the method further includes performing a patterning process on the epitaxial layer to form a plurality of light-emitting elements arranged in an array in the epitaxial layer.

[0050] In another aspect, a method for fabricating a display substrate is provided, comprising:

[0051] The light-emitting substrate is formed using the method described above;

[0052] A driving backplane is provided, the driving backplane comprising: a second substrate and a pad layer located on the side of the second substrate near the light-emitting substrate, the pad layer comprising a plurality of pads arranged in an array; and

[0053] Multiple light-emitting elements in the light-emitting substrate are aligned and bonded to multiple pads in the driving backplate.

[0054] According to some exemplary embodiments, the method further includes: removing the first adhesive layer and the first substrate from the light-emitting substrate.

[0055] According to some exemplary embodiments, the method further includes: thinning the surface of the bonding layer in the light-emitting substrate on the side away from the driving backplane to expose the surface of the optical adhesive layer away from the driving backplane.

[0056] According to some exemplary embodiments, the method further includes: ashing the optical adhesive layer to remove the optical adhesive layer and the bonding layer. Attached Figure Description

[0057] The foregoing contents, as well as other objects, features, and advantages of this disclosure, will become clearer from the following description of embodiments with reference to the accompanying drawings, in which:

[0058] Figures 1A-1D are flowcharts illustrating the fabrication process of a display substrate according to related technologies;

[0059] Figures 2A-2I are schematic flowcharts of an epitaxial layer transfer scheme according to related technologies;

[0060] Figures 3A-3F are schematic diagrams of another epitaxial layer transfer scheme according to related technologies;

[0061] Figure 4 is a schematic diagram of the product after the epitaxial layer is transferred to the target substrate according to the relevant technology;

[0062] Figure 5 is a schematic diagram of the structure of a light-emitting substrate according to an exemplary embodiment of the present disclosure;

[0063] Figures 6A-6C are partial planar schematic diagrams of the bonding layer, optical adhesive layer, and light-emitting layer according to exemplary embodiments of the present disclosure;

[0064] Figure 7A is a partial structural schematic diagram of the bonding layer, optical adhesive layer and light-emitting layer according to some embodiments of the present disclosure, and Figure 7B is a partial structural schematic diagram of the bonding layer, optical adhesive layer and light-emitting layer according to other embodiments of the present disclosure.

[0065] Figure 8 is a schematic diagram of the structure of a display substrate according to an exemplary embodiment of the present disclosure;

[0066] Figure 9 is a schematic diagram of the structure of a display substrate according to an exemplary embodiment of the present disclosure;

[0067] Figure 10 is a structural block diagram of a display device according to an exemplary embodiment of the present disclosure;

[0068] Figure 11 is a flowchart illustrating the fabrication process of a light-emitting substrate according to an exemplary embodiment of the present disclosure;

[0069] Figures 12A-12G are schematic diagrams of partial film layers during the fabrication process of a light-emitting substrate according to exemplary embodiments of the present disclosure;

[0070] Figure 13 is a flowchart illustrating the fabrication process of a display substrate according to an exemplary embodiment of the present disclosure; and

[0071] Figures 14A-14E are schematic diagrams of partial structures of some film layers during the fabrication process of a display substrate according to exemplary embodiments of the present disclosure.

[0072] It should be noted that, for clarity, the dimensions of layers, structures, or regions in the accompanying drawings used to describe embodiments of the present invention may be enlarged or reduced; that is, these drawings are not drawn to actual scale. Detailed Implementation

[0073] To make the objectives, technical solutions, and advantages of the embodiments of this disclosure clearer, the technical solutions of the embodiments of this disclosure will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some, not all, of the embodiments of this disclosure. All other embodiments obtained by those skilled in the art based on the described embodiments of this disclosure without creative effort are within the scope of protection of this disclosure.

[0074] It should be noted that, for clarity and / or descriptive purposes, the dimensions and relative dimensions of components may be enlarged in the accompanying drawings. Therefore, the dimensions and relative dimensions of the individual components are not necessarily limited to those shown in the drawings. In the specification and accompanying drawings, the same or similar reference numerals indicate the same or similar parts.

[0075] Unless otherwise defined, the technical or scientific terms used in this disclosure shall have the ordinary meaning understood by one of ordinary skill in the art. The terms “first,” “second,” and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different components. Terms such as “comprising” or “including” mean that an element or object preceding the word encompasses the elements or objects listed following the word and their equivalents, without excluding other elements or objects.

[0076] In this document, unless otherwise specified, directional terms such as "up," "down," "left," "right," "inner," and "outer" are used to indicate orientation or positional relationships based on the accompanying drawings, and are used only for the convenience of describing this disclosure, and are not intended to indicate or imply that the device, element, or component referred to must have a specific orientation, or be constructed or operated in a specific orientation. It should be understood that when the absolute position of the described object changes, the relative positional relationships they represent may also change accordingly. Therefore, these directional terms should not be construed as limitations on this disclosure.

[0077] In this document, the terms “approximately,” “about,” “approximately,” and other similar terms are used as terms of approximation rather than as terms of degree, and they are intended to account for inherent deviations in measured or calculated values ​​that would be recognized by one of ordinary skill in the art. Taking into account factors such as process variations, measurement problems, and errors associated with the measurement of a particular quantity (i.e., limitations of the measurement system), “about” or “approximately” as used herein includes stated values ​​and indicates that a particular value is within an acceptable range of deviation for one of ordinary skill in the art. For example, “about” may mean within one or more standard deviations, or within ±10% or ±5% of the stated value.

[0078] In this document, the directional terms "first direction," "second direction," and "third direction" are used to describe different orientations of the light-emitting substrate or display substrate, such as the row and column directions of the light-emitting elements. It should be understood that such representations are merely exemplary descriptions and not limitations of this disclosure.

[0079] In this document, unless otherwise stated, the term "electrical connection" can mean that two components or elements are directly electrically connected, for example, component or element A is in direct contact with component or element B, and an electrical signal can be transmitted between them; it can also mean that two components or elements are electrically connected through a conductive medium, such as a conductive wire, for example, component or element A is electrically connected to component or element B through a conductive wire to transmit an electrical signal between the two components or elements; it can also mean that two components or elements are electrically connected through at least one electronic component, for example, component or element A is electrically connected to component or element B through at least one thin-film transistor to transmit an electrical signal between the two components or elements.

[0080] In this article, "parallel" or "nearly parallel" refers to the state where the angle formed by two straight lines is greater than -10° and less than 10°, and therefore also includes the state where the angle is greater than -5° and less than 5°. In addition, "perpendicular" refers to the state where the angle formed by two straight lines is greater than 80° and less than 100°, and therefore also includes the state where the angle is greater than 85° and less than 95°.

[0081] To improve the quality of Micro LED chips, epitaxial layers are typically formed on epitaxial substrates such as sapphire or silicon wafers, and then patterned to form multiple Micro LED chips. Because the epitaxial substrate differs from some target substrates required in display applications (such as glass substrates), a large number of Micro LED chips typically need to be transferred from the epitaxial substrate to the target substrate when applying them to displays. Currently, mass transfer techniques are mainly used to transfer Micro LED chips to the target substrate, such as stamp-type and fluid self-alignment methods. However, these methods result in small transfer areas per operation, requiring multiple transfers, leading to low transfer efficiency and high costs.

[0082] Figures 1A-1D are flowcharts illustrating the fabrication process of a display substrate according to related technologies.

[0083] To improve the efficiency of transferring Micro LED chips to the target substrate, in conjunction with Figures 1A-1D, the related technologies employ a method of first transferring the epitaxial layer to the target substrate, and then using a patterning process to form multiple Micro LED chips in the epitaxial layer, thereby reducing the number of transfers and improving transfer efficiency. For example, referring to FIG1A, one or more structures comprising an epitaxial substrate 10 and an epitaxial layer 11 are transferred onto a target substrate 20 using a transfer tool TR, wherein the epitaxial layer 11 and the target substrate 20 can be connected by an adhesive layer 123; referring to FIG1B and FIG1C, after forming a protective layer 140 (e.g., an acid-resistant film) on the sides of the epitaxial layer 11 and the epitaxial substrate 10, the epitaxial substrate 10 is removed using an etching process (e.g., acid etching), and then a metal layer is formed on the epitaxial layer 11, and a patterning process is performed to form multiple Micro LED chips including a light-emitting body 110 and lead-out electrodes 111 in the epitaxial layer 11 and the metal layer; and referring to FIG1D, the multiple lead-out electrodes 111 of the multiple Micro LED chips are bonded to multiple pads 302 in a driving backplane 30, thereby forming a display substrate. The driving circuit in the driving backplane can drive one or more Micro LED chips to emit light, realizing the display of different images. This method allows multiple Micro LED chips to be formed directly in the epitaxial layer 11 on the target substrate 20 without having to transfer multiple Micro LED chips again, which can improve production efficiency and reduce costs.

[0084] However, in the current epitaxial layer transfer scheme, after the epitaxial layer is transferred to the target substrate, cracks and peripheral warping are easily caused in the epitaxial layer during or after the epitaxial substrate is peeled off. This is not conducive to the subsequent fabrication of Micro LED chips using the epitaxial layer, nor is it conducive to the subsequent alignment and bonding of Micro LED chips, thus leading to a decrease in the yield of the display substrate.

[0085] Figures 2A-2I are schematic flowcharts of one epitaxial layer transfer scheme according to the related art; Figures 3A-3F are schematic flowcharts of another epitaxial layer transfer scheme according to the related art; Figure 4 is a schematic diagram of the product after the epitaxial layer is transferred to the target substrate according to the related art.

[0086] In related technologies, epitaxial layer transfer schemes mainly employ adhesive materials (such as adhesive and release adhesive) to connect the transferred epitaxial layer to the target substrate. For example, in Scheme 1, referring to FIG2A, an adhesive layer (such as release adhesive layer 12 and adhesive layer 13) is formed on the epitaxial substrate 10 and the epitaxial layer 11; referring to FIG2B and FIG2C, the adhesive layer 13 is bonded to the target substrate 20 (such as a glass substrate). Exemplarily, the area of ​​the epitaxial layer 11 is smaller than the area of ​​the target substrate 20, which can achieve small-to-large bonding and ensure that the orthographic projection of the epitaxial layer 11 on the target substrate 20 falls into the target substrate 20; referring to FIG2D, after bonding is completed, an acid-resistant film 14 is formed around the epitaxial substrate 10, the epitaxial layer 11, the release adhesive layer 12 and the adhesive layer 13, and an acid-resistant UV-resistant film is formed on the edge region of the surface of the epitaxial substrate 10 away from the target substrate 20. Adhesive film 15; Referring to FIG2E, the epitaxial substrate 10 is etched, for example by acid etching, to remove most of the epitaxial substrate material; Referring to FIG2F, after the etching is completed, the acid-resistant film 14 and the acid-resistant UV adhesive film 15 are removed; Referring to FIG2G and FIG2H, the front laser lift-off technique and the back laser lift-off technique are used in sequence to perform laser lift-off on the edge regions of the epitaxial substrate 10, the epitaxial layer 11, the dissociative adhesive layer 12 and the adhesive layer 13 to remove the epitaxial substrate 10 remaining in the edge regions. For example, a 355 nm laser can be used for irradiation lift-off; and Referring to FIG2I, after the material of the epitaxial substrate 10 remaining in the edge regions is removed, the epitaxial layer 11 transferred to the target substrate 20 can be obtained.

[0087] For example, in Scheme 2, referring to Figure 3A, an adhesive layer (e.g., a release adhesive layer 12 and an adhesive layer 13) is formed on the epitaxial substrate 10 and the epitaxial layer 11; referring to Figures 3B and 3C, the adhesive layer 13 is bonded to the target substrate 20 (e.g., a glass substrate). Exemplarily, the area of ​​the epitaxial layer 11 is smaller than the area of ​​the target substrate 20, enabling a small-to-large fit and ensuring that the orthographic projection of the epitaxial layer 11 onto the target substrate 20 falls within the target substrate 20; referring to Figure 3D... After bonding is completed, an acid-resistant film 14 is formed around the epitaxial substrate 10, the epitaxial layer 11, the dissociative adhesive layer 12, and the adhesive layer 13. The acid-resistant film 14 can expose at least a portion of the upper surface and side surface of the epitaxial substrate 10. Referring to Figures 3D and 3E, the epitaxial substrate 10 is etched, for example, by acid etching, to remove the epitaxial substrate 10. Referring to Figures 3E and 3F, the acid-resistant film 14 is removed to obtain the epitaxial layer 11 transferred onto the target substrate 20.

[0088] However, regardless of whether it's Scheme 1 or Scheme 2, after the epitaxial substrate 10 (e.g., a silicon substrate) is etched and peeled off, the stress on the epitaxial layer 11, which was originally attached to the epitaxial substrate 10, is released. However, the adhesive layer 13 and the dissociative adhesive layer 12 below the epitaxial layer 11 have severely insufficient shear strength (e.g., about 3 MPa), which easily leads to cracks and warping around the epitaxial layer 11. For example, referring to Figure 4, a large number of cracks appear in the edge region of the epitaxial layer 11, which seriously affects the quality of the Micro LED chip subsequently fabricated using the epitaxial layer.

[0089] The inventors discovered that metal bonding can be used to increase the adhesion and shear strength between the epitaxial layer and the target substrate. Furthermore, to reduce the shading of the bonding metal layer on the light-emitting area of ​​the Micro LED chip, the bonding metal layer needs to be patterned.

[0090] For display semiconductor manufacturing processes, using common metals like copper for metal bonding requires high bonding temperatures (e.g., above 600°C), which can damage or fail some layers in the light-emitting substrate or display substrate, resulting in serious defects. Currently, low-temperature metal bonding is mainly used in silicon-based applications, such as silicon-based semiconductor processes, where patterning of silicon-based metal bonding can be achieved using printing equipment. However, for glass-based display semiconductor processes, firstly, if the metal bonding is patterned before bonding, the required alignment precision after bonding becomes too high, making accurate alignment difficult with existing equipment. Secondly, if patterning occurs after bonding, metal etching is difficult, hindering patterning and making low-temperature metal patterning impossible with existing solutions. This makes it difficult to implement solutions that use metal bonding to connect the epitaxial layer and the target substrate.

[0091] To balance the requirements of adhesion and shear strength between the epitaxial layer and the target substrate, as well as to meet the process requirements of glass-based semiconductor fabrication, embodiments of this disclosure provide a light-emitting substrate. The light-emitting substrate includes: a first substrate; a bonding layer located on one side of the first substrate, wherein at least a portion of the bonding layer on the side away from the first substrate includes a plurality of grooves; an optical adhesive layer located on the side of the bonding layer away from the first substrate, the optical adhesive layer including a plurality of isolation portions, the plurality of isolation portions respectively filling the plurality of grooves; and a light-emitting layer located on the side of the optical adhesive layer away from the first substrate, the light-emitting layer including a plurality of light-emitting elements arranged in an array, wherein the orthographic projections of the plurality of light-emitting elements on the first substrate at least partially overlap with the orthographic projections of the plurality of isolation portions on the first substrate; and the shear strength between the material of the light-emitting layer and the material of the bonding layer is greater than the shear strength between the material of the light-emitting layer and the material of the optical adhesive layer.

[0092] By forming a patterned structure on the epitaxial layer using an optical adhesive layer (e.g., the optical adhesive layer may include resin materials such as transparent optical adhesive), and then depositing bonding metal on top of the optical adhesive layer, excess bonding metal material can be removed by methods such as metal grinding or chemical etching after bonding is completed, thereby achieving the goal of bonding metal patterning. This design not only enables low-temperature metal patterning, but also ensures that the combined shear strength between the bonding metal layer, the optical adhesive layer, and the epitaxial layer is much greater than the shear strength between the individual adhesive layer (e.g., the adhesive layer 13 in Figure 3F) and the epitaxial layer. Therefore, it can be guaranteed that the epitaxial layer will not crack or warp after the epitaxial substrate is peeled off, which is beneficial for subsequent fabrication of Micro LED chips (e.g., multiple light-emitting elements in the light-emitting layer) using the epitaxial layer, and also facilitates the alignment and bonding of the subsequent Micro LED chips, thereby improving the yield of the display substrate.

[0093] Figure 5 is a schematic diagram of the structure of a light-emitting substrate according to an exemplary embodiment of the present disclosure.

[0094] Exemplary, in an embodiment of this disclosure, a light-emitting substrate 100 is provided. Referring to FIG5, the light-emitting substrate 100 may include: a first substrate 30, a bonding layer 31, an optical adhesive layer 32, and a light-emitting layer 33.

[0095] For example, the first substrate 30 may include a glass substrate. The first substrate 30 can serve as a target substrate for Micro LED chip transfer, providing support. It is also compatible with glass-based semiconductor processing technology in the display field, facilitating subsequent connection to the driving backplane and enabling the fabrication of display substrates or display devices using light-emitting substrates.

[0096] For example, the bonding layer 31 is located on one side of the first substrate 30. At least a portion of the bonding layer 31 on the side away from the first substrate includes a plurality of grooves 310.

[0097] For example, the bonding temperature of the bonding layer 31 is less than or equal to 280°C. By optimizing the material of the bonding layer, low-temperature metal bonding can be achieved, which can reduce the impact of the bonding process on the light-emitting substrate.

[0098] The optical adhesive layer 32 is located on the side of the bonding layer 31 away from the first substrate 30. The optical adhesive layer 32 includes a plurality of isolation portions 320, which respectively fill a plurality of grooves 310.

[0099] For example, the orthographic projection of the optical adhesive layer 32 on the first substrate falls within the orthographic projection of the plurality of grooves 310 on the first substrate.

[0100] In some embodiments, an optical adhesive layer may be prepared first, and a patterning process may be performed on the optical adhesive layer to form multiple isolation portions. Then, a bonding layer may be prepared, which can fill the gaps in the optical adhesive layer, thereby forming multiple grooves in the bonding layer.

[0101] With this design, patterned optical adhesive layers can be used to pattern local areas of the bonding layer 31, eliminating the need for subsequent patterning processes on the bonding layer after bonding, thus reducing process difficulty and saving costs.

[0102] For example, the bonding layer 31 may include a first sub-bonding layer 311 and a second sub-bonding layer 312. In the light emission direction Z of the light-emitting substrate, the height h1 of the first sub-bonding layer 311 is greater than the height h2 of the optical adhesive layer 32.

[0103] In some embodiments, the first sub-bonding layer 311 may be formed after the patterned optical adhesive layer 32 is formed. By designing the height of the first sub-bonding layer 311 to be greater than the height of the optical adhesive layer 32, the surface 3110 of the first sub-bonding layer can be exposed, which is beneficial for the bonding connection between the first sub-bonding layer 311 and the second sub-bonding layer 312.

[0104] The connection between the epitaxial layer and the first substrate can be achieved through the bonding of the first sub-bonding layer and the second sub-bonding layer. In other words, the epitaxial layer can be transferred from the epitaxial substrate (e.g., silicon substrate) to the first substrate 30 (e.g., glass substrate) through the bonding connection of the two sub-bonding layers. After removing the epitaxial substrate and performing a patterning process on the epitaxial layer, the light-emitting layer 33 shown in FIG5 can be formed.

[0105] In some embodiments, after stripping the epitaxial substrate, one or more film layers (e.g., conductive layers, insulating layers, etc.) can be formed on the side of the epitaxial layer away from the first substrate. A patterning process is then performed on the one or more film layers to form multiple lead-out electrodes. The multiple lead-out electrodes may include at least one of the cathode or anode of the light-emitting element. This design enables the lead-out of the electrodes of the light-emitting element, facilitating subsequent bonding of the light-emitting element to the driving backplane.

[0106] For example, in the light emission direction Z of the light-emitting substrate, the height h2 of the optical adhesive layer is in the range of 1 micrometer to 10 micrometers.

[0107] By designing the optical adhesive layer to be thinner, the surface 3110 of the first sub-bonding layer can be made flatter, which is beneficial for the bonding connection between the first sub-bonding layer 311 and the second sub-bonding layer 312.

[0108] For example, the materials of the first sub-bonding layer 311 and the second sub-bonding layer 312 can be the same or different. For instance, the material of the first sub-bonding layer 311 may include gold, silver, and tin metals or metal alloys; and the material of the second sub-bonding layer 312 may include gold, silver, and tin metals or metal alloys. By employing two low-temperature bonding metals, the epitaxial layer can be transferred to the first substrate using low-temperature bonding technology, avoiding damage to the film layer caused by high-temperature bonding processes and improving the yield of the light-emitting substrate.

[0109] For example, the light-emitting layer 33 is located on the side of the optical adhesive layer 32 away from the first substrate 30. The light-emitting layer 33 includes a plurality of light-emitting elements 330 arranged in an array.

[0110] For example, the light-emitting layer 33 is in direct contact with the optical adhesive layer 32.

[0111] For example, a portion of the light-emitting layer 33 may be in direct contact with the optical adhesive layer 32, and another portion of the light-emitting layer 33 may be in direct contact with the bonding layer 31.

[0112] For example, the light-emitting layer 33 may include an epitaxial layer and one or more conductive layers. By performing a patterning process on the epitaxial layer and the conductive layer, a plurality of light-emitting elements 330 can be formed.

[0113] For example, the light-emitting element 330 may include one or more Micro LED chips of different colors. For instance, the light-emitting element 330 may include one or more of red, green, blue, and white Micro LED chips. The Micro LED chips can emit light under the control of an external driving voltage.

[0114] For example, the orthographic projections of the plurality of light-emitting elements 330 on the first substrate 30 at least partially overlap with the orthographic projections of the plurality of isolation portions 320 on the first substrate. For instance, the orthographic projection of one light-emitting element 330 on the first substrate 30 may at least partially overlap with the orthographic projection of one isolation portion 320 on the first substrate.

[0115] In some embodiments of this disclosure, a patterned optical adhesive layer is used to pattern a portion of the bonding layer 31, eliminating the need for post-bonding patterning of the bonding metal. This enables low-temperature bonding metal patterning and ensures compatibility with glass-based semiconductor processing techniques. This design allows for metal bonding to connect the epitaxial layer (e.g., a portion of the light-emitting layer 33) to the target substrate (e.g., the first substrate 30), improving adhesion and shear strength between the epitaxial layer and the target substrate while meeting the processing requirements of glass-based semiconductors.

[0116] For example, the light-emitting substrate may further include a first adhesive layer 34 located between the first substrate 30 and the bonding layer 31. The first adhesive layer 34 may include a release adhesive, which allows the first substrate 30 to be peeled off by removing the first adhesive layer 34 during the subsequent fabrication of the display substrate using the light-emitting substrate.

[0117] Figures 6A-6C are partial planar schematic diagrams of the bonding layer, optical adhesive layer, and light-emitting layer according to exemplary embodiments of the present disclosure.

[0118] For example, in embodiments of this disclosure, multiple light-emitting elements 330 can be disposed in areas corresponding to multiple isolation portions 320. For instance, one light-emitting element 330 can be disposed in the area above one isolation portion 320.

[0119] In some embodiments, a plurality of light-emitting elements 330 and a plurality of isolation portions 320 may be arranged in a one-to-one correspondence. The orthographic projection of the light-emitting element 330 onto the first substrate has a first projected area, and the orthographic projection of the isolation portion 320 onto the first substrate has a second projected area. The first projected area of ​​the light-emitting element 330 may be substantially equal to the second projected area of ​​the corresponding isolation portion 320, for example, the ratio of the first projected area to the second projected area is in the range of 0.9-1.1; or, the first projected area of ​​the light-emitting element 330 may be slightly larger than the second projected area of ​​the corresponding isolation portion 320, for example, the ratio of the first projected area to the second projected area is in the range of 1.1-1.3; or, the first projected area of ​​the light-emitting element 330 may be slightly smaller than the second projected area of ​​the corresponding isolation portion 320, for example, the ratio of the first projected area to the second projected area is in the range of 0.7-0.9.

[0120] For example, referring to FIG6A, at least a portion of the isolation portion 320 is projected onto the first substrate 30 and is completely overlapped with the projected onto the first substrate 30 of at least a portion of the light-emitting element 330.

[0121] For example, referring to FIG6B, at least a portion of the light-emitting elements 330 are projected onto the first substrate 30 and fall into the projection of at least a portion of the isolation portion 320 onto the first substrate 30.

[0122] For example, referring to FIG6C, at least a portion of the isolation portion 320 is projected onto the first substrate 30 and falls into the projection of at least a portion of the light-emitting element 330 onto the first substrate 30.

[0123] For example, a portion of the light-emitting layer 33 may be in direct contact with the optical adhesive layer 32, and another portion of the light-emitting layer 33 may be in direct contact with the bonding layer 31.

[0124] In some embodiments, the patterning of the bonding layer (e.g., multiple groove structures) is formed according to the shape of multiple isolation portions. Through the corresponding design of multiple light-emitting elements and multiple isolation portions, the patterned structure of the bonding layer can be more closely matched to the arrangement of the multiple light-emitting elements. When subsequently fabricating a display substrate using the light-emitting substrate, excess bonding metal can be removed, retaining only a portion of the patterned structure (e.g., retaining a portion of the bonding metal between the spacing regions of the multiple isolation portions). This reduces the shading of the light-emitting area of ​​the light-emitting elements by the bonding layer, which is beneficial for improving the light emission effect of the multiple light-emitting elements.

[0125] For example, the shear strength between the material of the light-emitting layer 33 and the material of the bonding layer 31 is greater than the shear strength between the material of the light-emitting layer 33 and the material of the optical adhesive layer 32. For example, the light-emitting layer 33 may include an inorganic semiconductor material, the bonding layer 31 may include a metallic material, and the optical adhesive layer 32 may include an organic resin material.

[0126] In some embodiments, the light-emitting layer 33 can be formed by a patterning process using an epitaxial layer bonded to one or more conductive layers. The light-emitting layer 33 may include an epitaxial layer. Before performing a patterning process on the epitaxial layer and conductive layer to form the light-emitting layer, the epitaxial layer may be fully bonded to the common surface formed by both the bonding layer 31 and the optical adhesive layer 32.

[0127] For example, the epitaxial layer mainly comprises inorganic semiconductor materials, such as gallium nitride and gallium arsenide. Since the shear strength (e.g., greater than 10 MPa) between the epitaxial layer material and the metal material (e.g., the material of bonding layer 31) is greater than the shear strength (e.g., about 3 MPa) between the epitaxial layer material and the organic adhesive material (e.g., the material of optical adhesive layer 32), using a bonding metal to achieve epitaxial layer transfer better ensures adhesion and shear strength between the epitaxial layer and the target substrate, preventing cracks or edge warping of the epitaxial layer after transfer to the first substrate. For example, compared to the scheme shown in FIG3F, in which the transferred epitaxial layer 11 is connected to the target substrate 20 via an adhesive layer (e.g., dissociative adhesive layer 12 and adhesive layer 13), in FIG5, before the patterning process is performed, the epitaxial layer contained in the light-emitting layer 33 can be connected to the common surface formed by the bonding layer 31 and the optical adhesive layer 32, thereby improving the adhesion and shear strength between the epitaxial layer and the first substrate, and preventing cracks or edge warping of the epitaxial layer after it is transferred to the first substrate.

[0128] This design improves the quality of the epitaxial layer transferred onto the first substrate, thereby increasing the yield of multiple light-emitting elements in the light-emitting layer formed on the first substrate using the epitaxial layer and conductive layer, which is beneficial for improving the yield of the light-emitting substrate.

[0129] Figure 7A is a partial structural schematic diagram of the bonding layer, optical adhesive layer and light-emitting layer according to some embodiments of the present disclosure, and Figure 7B is a partial structural schematic diagram of the bonding layer, optical adhesive layer and light-emitting layer according to other embodiments of the present disclosure.

[0130] Exemplary examples, in some embodiments of this disclosure, referring to Figures 7A and 7B, show that the light-emitting layer 33 may include a first functional layer G1. The first functional layer G1 is located on the side of the light-emitting layer 33 closer to the optical adhesive layer 32. Most of the light emitted by the light-emitting element 330 can be emitted in the direction closer to the optical adhesive layer 32.

[0131] For example, the first functional layer G1 may include a conductive material or an inorganic semiconductor material.

[0132] For example, the shear strength between the material of the first functional layer G1 and the material of the bonding layer 31 is greater than or equal to 10 MPa.

[0133] For example, at least one light-emitting element 330 may include a lead-out electrode located on the surface of the light-emitting element 330 away from the first substrate. For instance, the second electrode M2 ​​in FIG. 7A may be a lead-out electrode, and the first electrode M1 and the second electrode M2 ​​in FIG. 7B may be lead-out electrodes. During subsequent fabrication of the display substrate, the lead-out electrodes may be used for bonding connections with a driving backplane.

[0134] Exemplarily, in embodiments of this disclosure, the light-emitting element 330 may include a vertical Micro LED chip. For example, referring to FIG7A, the light-emitting element 330 may include a first electrode M1, a first semiconductor layer 1101, a quantum well layer 1102, a second semiconductor layer 1103, and a second electrode M2, which are sequentially stacked. The first semiconductor layer 1101, the quantum well layer 1102, and the second semiconductor layer 1103 may be formed after the epitaxial layer 11 has undergone a patterning process. The first electrode M1 may be formed before the epitaxial layer 11 is transferred to the first substrate, and the second electrode M2 ​​may be formed after the epitaxial layer 11 is transferred to the first substrate. During the subsequent fabrication of the display substrate, when the light-emitting substrate is connected to the driving backplane, the second electrode M2 ​​can be used to align and bond with the pads on the driving backplane, thereby enabling the driving backplane to drive the light-emitting element 330 to emit light.

[0135] For example, the first electrode M1 may be located in the first functional layer G1. The material of the first functional layer G1 may include a conductive material, such as an ultrathin metal or an inorganic transparent conductive material. The first electrode M1 has high transparency, which ensures that most of the emitted light from the light-emitting element 330 can pass through the first electrode M1 and be emitted to the outside, thereby ensuring the light-emitting effect of the light-emitting substrate.

[0136] The second electrode M2 ​​can be a thicker metal layer, such as copper metal ranging from 0.5 micrometers to 50 micrometers, to facilitate subsequent bonding with the drive backplane.

[0137] Exemplarily, the light-emitting element 330 may include a flip-chip MicroLED chip. For example, referring to FIG7B, the light-emitting element 330 may include a first semiconductor layer 1101, a quantum well layer 1102, and a second semiconductor layer 1103 stacked sequentially. The light-emitting element 330 may also include a first electrode M1 and a second electrode M2 ​​located on the side of the second semiconductor layer 1103 away from the optical adhesive layer 32. The first semiconductor layer 1101, the quantum well layer 1102, and the second semiconductor layer 1103 may be formed after the epitaxial layer 11 is patterned. Both the first electrode M1 and the second electrode M2 ​​may be formed after the epitaxial layer 11 is transferred to the first substrate. During the subsequent fabrication of the display substrate, when the light-emitting substrate is connected to the driving backplane, both the first electrode M1 and the second electrode M2 ​​may be used to align and bond with the pads on the driving backplane, thereby enabling the driving backplane to drive the light-emitting element 330 to emit light.

[0138] By combining patterned bonding layers and optical adhesive layers, not only can the transfer of the epitaxial layer to the first substrate be largely free of cracks or edge warping, but the optical adhesive layer also serves for alignment and light emission. Most of the light emitted by the Micro LED chip can be emitted through the optical adhesive layer, which helps improve the light emission performance of the light-emitting substrate.

[0139] It should be noted that Figures 7A and 7B schematically illustrate two LED chip structures, but the embodiments of this disclosure are not limited to these. In the embodiments of this disclosure, the LED chip may also include other additional film layers, and may also employ various other structural designs known in the art.

[0140] For example, referring back to FIG5, the surface 3201 of the optical adhesive layer 32 away from the first substrate and the surface 3101 of the bonding layer 31 away from the first substrate can form a planarized surface.

[0141] This design improves the quality of the epitaxial layer transferred to the common surface of the optical adhesive layer 32 and the bonding layer 31, thereby increasing the yield of the Micro LED chip formed using the epitaxial layer. Furthermore, when multiple Micro LED chips in the light-emitting substrate are subsequently aligned and bonded to multiple pads in the driving backplane, the planarized surface enhances the bonding effect between the Micro LED chips and the pads in the driving backplane, thus improving the yield of the display substrate.

[0142] Figure 8 is a schematic diagram of the structure of a display substrate according to an exemplary embodiment of the present disclosure.

[0143] Exemplary, in an embodiment of this disclosure, a display substrate 200 is provided. Referring to FIG8, the display substrate 200 may include a second substrate 51, a pad layer 52, a light-emitting layer 33, an optical adhesive layer 32, and a bonding layer 31.

[0144] For example, the pad layer 52 is located on one side of the second substrate 51, and the pad layer includes a plurality of pads 520 arranged in an array. For example, the driving backplane 50 in the display substrate may include the second substrate 51 and the pad layer 52. The second substrate 51 may also include a driving circuit layer for driving the light-emitting elements to emit light, and the pad layer 52 may be used to electrically connect with the light-emitting elements, transmitting signals from the driving circuit layer to the light-emitting elements, thereby controlling multiple light-emitting elements to achieve different screen displays.

[0145] For example, the light-emitting layer 33 is located on the side of the pad layer 52 away from the second substrate 51. The light-emitting layer 33 may include a plurality of light-emitting elements 330 arranged in an array. At least a portion of the pads 52 are electrically connected to at least a portion of the light-emitting elements 33.

[0146] For example, the optical adhesive layer 32 is located on the side of the light-emitting layer 33 away from the second substrate 51. The optical adhesive layer 32 may include a plurality of insulating portions 320 and a plurality of first openings VH1 located between the plurality of insulating portions.

[0147] For example, at least a portion of the bonding layer 31 may fill a plurality of first openings VH1.

[0148] For example, the shear strength between the material of the light-emitting layer 33 and the material of the bonding layer 31 is greater than the shear strength between the material of the light-emitting layer 33 and the material of the optical adhesive layer 32.

[0149] In some embodiments, the display substrate 200 can be formed using the light-emitting substrate 100 provided in any of the foregoing embodiments. For example, after the light-emitting substrate 100 shown in FIG. 5 is bonded to the driving backplate 50, the first substrate 30 and the first adhesive layer 34 are removed using laser lift-off technology, and then the bonding layer 31 is thinned to form the display substrate 200 shown in FIG. 8. It should be understood that this display substrate 200 has the same beneficial effects as the light-emitting substrate 100 provided in the foregoing embodiments.

[0150] According to some exemplary embodiments, in the light-emitting direction Z1 of the display substrate, the height h3 of the bonding layer 31 is equal to the height h4 of the optical adhesive layer 32. For example, referring to Figures 5 and 8, the bonding layer 31 can be thinned, for example by metal polishing or chemical etching, to remove excess thickness of the bonding layer and expose the interfacial surfaces of the optical adhesive layer 32 and the bonding layer 31.

[0151] For example, the bonding layer 31 includes a plurality of light-shielding portions 318. The orthographic projection of the light-shielding portions 318 on the second substrate 51 lies within the orthographic projection of the plurality of first openings VH1 on the second substrate.

[0152] The optical adhesive layer 32 has high transmittance, allowing most of the light emitted by the light-emitting element 330 to pass through it and be emitted outwards. The light-shielding portion 318 in the spaced area of ​​the optical adhesive layer 32 can block side leakage light from the light-emitting element 330, thereby preventing crosstalk.

[0153] For example, the surface 3201 of the optical adhesive layer 32 near the second substrate and the surface 3101 of the bonding layer 31 near the second substrate form a planarized surface.

[0154] This design improves the bonding effect between the light-emitting element 330 and the pad 520, thereby increasing the yield of the display substrate.

[0155] In some embodiments, continuing to refer to FIG8, the display substrate 200 may further include an insulating layer 53. The insulating layer 53 is located between the pad layer 52 and the light-emitting layer 33, and the insulating layer 53 may include a plurality of second openings VH2. The plurality of second openings VH2 may respectively expose at least a portion of the surface 5201 of the plurality of pads 520 away from the second substrate.

[0156] The insulating layer can protect the pad layer 52, prevent the pad layer from being oxidized, and thus improve the electrical connection performance between the pad layer and the light-emitting layer.

[0157] Figure 9 is a schematic diagram of the structure of a display substrate according to an exemplary embodiment of the present disclosure.

[0158] Exemplary examples, in some embodiments of this disclosure, the optical adhesive layer 32 in the display substrate shown in FIG8 can also be ashed to remove the optical adhesive layer 32 and the bonding layer 31, forming the display substrate shown in FIG9. This design reduces the thickness of the display substrate, facilitating its thinning and lightening.

[0159] Figure 10 is a structural block diagram of a display device according to an exemplary embodiment of the present disclosure.

[0160] Optionally, embodiments of this disclosure also provide a display device. Referring to FIG10, the display device 300 may include the aforementioned light-emitting substrate 100 or display substrate 200. The display device may include, but is not limited to, any product or component with display function such as electronic paper, mobile phone, tablet computer, monitor, laptop computer, digital photo frame, and navigator. It should be understood that this display device has the same beneficial effects as the light-emitting substrate or display substrate provided in the foregoing embodiments.

[0161] Figure 11 is a flowchart of the fabrication process of a light-emitting substrate according to an exemplary embodiment of the present disclosure, and Figures 12A-12G are schematic diagrams of the partial structure of some film layers during the fabrication process of a light-emitting substrate according to an exemplary embodiment of the present disclosure.

[0162] By way of example, in an embodiment of this disclosure, a method for fabricating a light-emitting substrate is provided. For example, referring to FIG11, the method for fabricating a light-emitting substrate may include the following steps S01-S07.

[0163] In step S01, referring to FIG12A, an epitaxial substrate 10 is provided. For example, the epitaxial substrate 10 may include a silicon substrate or a sapphire-based substrate. An epitaxial layer 11 is formed on the epitaxial substrate 10, and the epitaxial layer 11 may include multiple film layers, such as a P-type semiconductor layer, a quantum well layer, and an N-type semiconductor layer.

[0164] In step S02, referring to FIG12B, an optical adhesive material layer is formed on the side of the epitaxial layer 11 away from the epitaxial substrate 10, and a patterning process is performed to form an optical adhesive layer 32. The optical adhesive layer 32 may include a plurality of isolation portions 320 and a plurality of first openings VH1 located between the plurality of isolation portions 320.

[0165] In step S03, referring to FIG12C, a first sub-bonding layer 311 is formed on the side of the optical adhesive layer 32 away from the epitaxial substrate 10. The first sub-bonding layer 311 fills a plurality of first openings VH1 in the optical adhesive layer 32 to form a first portion P1 including the epitaxial substrate 10, the epitaxial layer 11, the optical adhesive layer 32 and the first sub-bonding layer 311.

[0166] This method allows for the use of patterned optical adhesive layers to pattern a portion of the first sub-bonding layer, avoiding the need to perform patterning on the bonding metals after bonding. This reduces the complexity of the process and saves costs.

[0167] For example, the thickness of the first sub-bonding layer 311 is higher than the thickness of the optical adhesive layer 32, ensuring that the surface 3110 of the first sub-bonding layer 311 away from the epitaxial substrate is further away from the epitaxial substrate 10 than the surface 3201 of the optical adhesive layer 32 away from the epitaxial substrate, so as to facilitate the bonding connection of the first sub-bonding layer 311 with other metal layers (e.g., the second sub-bonding layer 312).

[0168] For example, the thickness of the optical adhesive layer can be set to be relatively thin, for example, in the range of 1 micrometer to 10 micrometers, which can make the surface 311 of the first sub-bonding layer 311 away from the epitaxial substrate 3110 flatter, resulting in better subsequent bonding effect.

[0169] In step S04, referring to FIG12D, a first substrate 30 is provided; a first adhesive layer 34 is formed on one side of the first substrate 30; a second sub-bonding layer 312 is formed on the side of the first adhesive layer 34 away from the first substrate 30, so as to form a second portion P2 including the first substrate 30, the first adhesive layer 34 and the second sub-bonding layer 312.

[0170] Exemplarily, the first substrate 30 may include a glass substrate as the target substrate for epitaxial layer transfer. The first adhesive layer 34 may include a release adhesive to facilitate the removal of the first substrate during subsequent fabrication of the display substrate. The second sub-bonding layer 312 may include a low-temperature bonding metal for bonding with the first sub-bonding layer.

[0171] In step S05, referring to FIG12E, the first sub-bonding layer 311 in the first part P1 and the second sub-bonding layer 312 in the second part P2 are bonded together, wherein the first sub-bonding layer 311 and the second sub-bonding layer 312 form a bonding layer 31.

[0172] The first sub-bonding layer 311 and the second sub-bonding layer 312 can be bonded across the entire surface, which has low requirements for bonding alignment and makes it easier to achieve the bonding connection between the first sub-bonding layer 311 and the second sub-bonding layer 312.

[0173] For example, both the first sub-bonding layer 311 and the second sub-bonding layer 312 can be low-temperature bonding metals, such as Ag-Sn or Au-Sn. The epitaxial layer 11 is transferred to the first substrate 30 by low-temperature bonding (e.g., bonding at a temperature below 280°C).

[0174] This method avoids damage to the film layer during the bonding process, which helps to improve the yield of the light-emitting substrate.

[0175] In step S06, referring to FIG12F, the method for fabricating the light-emitting substrate further includes: peeling off the epitaxial substrate 10. For example, the epitaxial substrate 10 (e.g., a silicon substrate) can be etched using a hydrofluoric acid solution to complete the peeling off of the epitaxial substrate.

[0176] In this way, the epitaxial layer 11 and the first substrate 30 are connected together by the bonding layer 31 and the optical adhesive layer 32, resulting in a high bonding strength. This not only improves the adhesion between the epitaxial layer 11 and the first substrate 30, preventing cracks or edge warping of the epitaxial layer 11 after it is peeled off from the epitaxial substrate 10, but also enables the patterning of the bonding metal, which is beneficial for the subsequent alignment of LED chips fabricated using the epitaxial layer and also helps to improve the light extraction effect of the LED chip.

[0177] In step S07, referring to FIG12G, the method for fabricating the light-emitting substrate further includes: performing a patterning process on the epitaxial layer 11 to form a plurality of light-emitting elements 330 arranged in an array in the epitaxial layer.

[0178] In some embodiments, referring to 12H, before performing a patterning process on the epitaxial layer 11, a conductive layer M3 may be formed on the side of the epitaxial layer 11 away from the first substrate 30, and then a patterning process may be performed on the epitaxial layer 11 and the conductive layer M3 to form a plurality of light-emitting elements 330 arranged in an array. Alternatively, after performing a patterning process on the epitaxial layer 11, a conductive layer M3 may be formed on the side of the epitaxial layer 11 away from the first substrate 30, and then a patterning process may be performed on the conductive layer M3 to form a plurality of light-emitting elements 330 arranged in an array.

[0179] For example, the conductive layer M3 can be used to bond to the driving circuit, such as to the pads in the driving backplane, so as to transmit the driving signal to the light-emitting element 330.

[0180] Figure 13 is a flowchart of the fabrication process of a display substrate according to an exemplary embodiment of the present disclosure, and Figures 14A-14E are schematic diagrams of the partial structure of some film layers during the fabrication process of a display substrate according to an exemplary embodiment of the present disclosure.

[0181] By way of example, in an embodiment of this disclosure, a method for fabricating a display substrate is also provided. For example, referring to FIG13, the method for fabricating a display substrate may include the following steps S21-S25.

[0182] In step S21, referring to FIG12G or 12H, the light-emitting substrate 100 is formed by the method described in any of the above embodiments.

[0183] In step S22, referring to FIG14A, a driving backplane 50 is provided. The driving backplane includes a second substrate 51 and a pad layer 52 located on the side of the second substrate 51 near the light-emitting substrate. The pad layer 52 may include a plurality of pads 520 arranged in an array. For example, a patterning process can be performed on the pad layer 52 to form a plurality of pads 520 arranged in an array.

[0184] For example, multiple pads 520 and multiple light-emitting elements 330 in the light-emitting substrate 100 can be arranged in a one-to-one correspondence to facilitate alignment and bonding connection.

[0185] In some embodiments, the method for fabricating the display substrate may further include forming an insulating layer 53 on the side of the pad layer 52 away from the second substrate 51, and performing a patterning process on the insulating layer 53 to form a plurality of second openings VH2 in the insulating layer 53. The plurality of second openings VH2 may respectively expose at least a portion of the surface 5201 of the plurality of pads 520 away from the second substrate, so as to facilitate bonding connection with the light-emitting element.

[0186] The insulating layer can protect the pad layer 52, prevent the pad layer from being oxidized, and thus improve the electrical connection performance between the pad layer and the light-emitting layer.

[0187] In step S23, referring to FIG14B, a plurality of light-emitting elements 330 in the light-emitting substrate 100 are aligned and bonded to a plurality of pads 520 in the driving backplate.

[0188] In step S24, referring to Figures 14B and 14C, the method for fabricating the display substrate may further include removing the first adhesive layer 34 and the first substrate 30 from the light-emitting substrate. For example, laser lift-off technology can be used to remove the first adhesive layer 34 and the first substrate 30.

[0189] In step S25, referring to Figures 14C and 14D, the method for fabricating the display substrate may further include: thinning the bonding layer on the side of the light-emitting substrate away from the driving backplane to expose the surface 3201 of the optical adhesive layer away from the driving backplane. For example, the excess thickness of the bonding layer 31 can be removed by means of metal polishing or chemical etching to expose the surface between the optical adhesive layer and the bonding layer.

[0190] This method allows for the patterning of the bonding metal while ensuring that the front light-emitting area of ​​the light-emitting element is primarily covered by a high-transmittance optical adhesive layer, which improves the light extraction efficiency of the light-emitting element. Simultaneously, the remaining bonding layer in the gaps between the optical adhesive layers can also block the side light emission from the light-emitting element, thus preventing crosstalk.

[0191] In some embodiments, referring to Figures 14D and 14E, the method for fabricating the display substrate may further include step S26: ashing the optical adhesive layer 32 to remove the optical adhesive layer 32 and the bonding layer 31. Since the bonding layer 31 is mainly connected to the light-emitting layer 33 through the optical adhesive layer 32, the bonding layer 31 can also be removed after the optical adhesive layer 32 is removed.

[0192] This method can reduce the thickness of the display substrate, which is beneficial for making the display substrate thinner and lighter.

[0193] In some embodiments, one or more other functional film layers, such as a light-emitting structure, a filter film, and a light-shielding layer, may be formed on the side of the light-emitting layer 33 away from the second substrate 51 to improve the display effect of the display substrate.

[0194] It should be understood that the method for preparing the display substrate in the above embodiments has the same beneficial effects as the method for preparing the light-emitting substrate provided in the foregoing embodiments.

[0195] While some embodiments of the general concept of this disclosure have been shown and described, those skilled in the art will understand that changes may be made to these embodiments without departing from the principles and spirit of the general concept of this disclosure, the scope of which is defined by the claims and their equivalents.

Claims

1. A light-emitting substrate, characterized in that, include: First substrate; A bonding layer located on one side of the first substrate, wherein at least a portion of the bonding layer on the side away from the first substrate includes a plurality of grooves; An optical adhesive layer is located on the side of the bonding layer away from the first substrate. The optical adhesive layer includes a plurality of isolation portions, which respectively fill the plurality of grooves. and A light-emitting layer is located on the side of the optical adhesive layer away from the first substrate, and the light-emitting layer includes a plurality of light-emitting elements arranged in an array. Wherein, the orthographic projections of the plurality of light-emitting elements on the first substrate at least partially overlap with the orthographic projections of the plurality of isolation portions on the first substrate; as well as The shear strength between the material of the light-emitting layer and the material of the bonding layer is greater than the shear strength between the material of the light-emitting layer and the material of the optical adhesive layer.

2. The light-emitting substrate according to claim 1, wherein, The orthographic projection of the optical adhesive layer on the first substrate falls within the orthographic projection of the plurality of grooves on the first substrate; And / or, The optical adhesive layer and the bonding layer form a planarized surface on the surface away from the first substrate.

3. The light-emitting substrate according to claim 2, wherein, The light-emitting layer includes a first functional layer, which is located on the side of the light-emitting layer closest to the optical adhesive layer. Wherein, the first functional layer comprises a conductive material or an inorganic semiconductor material; and / or, the shear strength between the material of the first functional layer and the material of the bonding layer is greater than or equal to 10 MPa.

4. The light-emitting substrate according to any one of claims 1-3, wherein, At least a portion of the isolation portion's orthographic projection on the first substrate completely overlaps with at least a portion of the light-emitting element's orthographic projection on the first substrate; as well as The light-emitting layer is in direct contact with the optical adhesive layer.

5. The light-emitting substrate according to any one of claims 1-3, wherein, At least a portion of the isolation portions have their orthographic projections on the first substrate falling within the orthographic projections of at least a portion of the light-emitting elements on the first substrate; as well as A portion of the light-emitting layer is in direct contact with the optical adhesive layer, and another portion of the light-emitting layer is in direct contact with the bonding layer.

6. The light-emitting substrate according to any one of claims 1-5, wherein, At least one of the light-emitting elements includes an electrode that is located on a surface of the light-emitting element away from the first substrate.

7. The light-emitting substrate according to any one of claims 1-6, wherein, The first substrate includes a glass substrate; and / or, The bonding temperature of the bonding layer is less than or equal to 280°C.

8. The light-emitting substrate according to claim 7, wherein, The bonding layer includes a first sub-bonding layer, wherein, in the light emission direction of the light-emitting substrate, the height of the first sub-bonding layer is greater than the height of the optical adhesive layer; and / or, In the light-emitting direction of the light-emitting substrate, the height of the optical adhesive layer is in the range of 1 micrometer to 10 micrometers.

9. The light-emitting substrate according to claim 8, wherein, The material of the first sub-bonding layer includes gold, silver, and tin metals or metal alloys; and The bonding layer further includes a second sub-bonding layer, the material of which includes gold, silver and tin metals or metal alloys.

10. A display substrate, characterized in that, include: Second substrate; A pad layer, the pad layer being located on one side of the second substrate, the pad layer comprising a plurality of pads arranged in an array; A light-emitting layer is located on the side of the pad layer away from the second substrate. The light-emitting layer includes a plurality of light-emitting elements arranged in an array, and at least a portion of the pads are electrically connected to at least a portion of the light-emitting elements. An optical adhesive layer is located on the side of the light-emitting layer away from the second substrate, and the optical adhesive layer includes a plurality of isolation portions and a plurality of first openings located between the plurality of isolation portions; and A bonding layer, at least a portion of which fills the plurality of first openings. Wherein, the shear strength between the material of the light-emitting layer and the material of the bonding layer is greater than the shear strength between the material of the light-emitting layer and the material of the optical adhesive layer.

11. The display substrate according to claim 10, wherein, In the light-emitting direction of the display substrate, the height of the bonding layer is equal to the height of the optical adhesive layer; and The bonding layer includes a plurality of light-shielding portions, and the orthographic projection of the light-shielding portions on the second substrate is located in the orthographic projection of the plurality of first openings on the second substrate.

12. The display substrate according to claim 11, wherein, The optical adhesive layer and the bonding layer, both near the second substrate, form a planarized surface.

13. The display substrate according to any one of claims 10-12, wherein, The display substrate further includes an insulating layer located between the pad layer and the light-emitting layer. The insulating layer includes a plurality of second openings, each of which exposes at least a portion of the surface of the plurality of pads away from the second substrate.

14. A display device comprising a light-emitting substrate as described in any one of claims 1-9 or a display substrate as described in any one of claims 10-13.

15. A method for preparing a light-emitting substrate, characterized in that, include: Provide epitaxial substrates; An epitaxial layer is formed on the epitaxial substrate; An optical adhesive material layer is formed on the side of the epitaxial layer away from the epitaxial substrate, and a patterning process is performed to form the optical adhesive layer, wherein the optical adhesive layer includes a plurality of isolation portions and a plurality of first openings located between the plurality of isolation portions; A first sub-bonding layer is formed on the side of the optical adhesive layer away from the epitaxial substrate. The first sub-bonding layer fills a plurality of first openings in the optical adhesive layer to form a first portion comprising the epitaxial substrate, the epitaxial layer, the optical adhesive layer, and the first sub-bonding layer. Provide a first substrate; A first adhesive layer is formed on one side of the first substrate; A second sub-bonding layer is formed on the side of the first adhesive layer away from the first substrate to form a second portion comprising the first substrate, the first adhesive layer and the second sub-bonding layer; The first sub-bonding layer in the first part and the second sub-bonding layer in the second part are bonded together, wherein the first sub-bonding layer and the second sub-bonding layer form a bonding layer.

16. The method according to claim 15, wherein, The method further includes: stripping the epitaxial substrate.

17. The method according to claim 16, wherein, The method further includes performing a patterning process on the epitaxial layer to form a plurality of light-emitting elements arranged in an array in the epitaxial layer.

18. A method for preparing a display substrate, characterized in that, include: The light-emitting substrate is formed by the method as described in claim 17; A driving backplane is provided, the driving backplane comprising: a second substrate and a pad layer located on the side of the second substrate near the light-emitting substrate, the pad layer comprising a plurality of pads arranged in an array; as well as Multiple light-emitting elements in the light-emitting substrate are aligned and bonded to multiple pads in the driving backplate.

19. The method according to claim 18, wherein, The method further includes removing the first adhesive layer and the first substrate from the light-emitting substrate.

20. The method according to claim 19, wherein, The method further includes: thinning the surface of the bonding layer in the light-emitting substrate away from the driving backplate to expose the surface of the optical adhesive layer away from the driving backplate.

21. The method according to claim 20, wherein, The method further includes: ashing the optical adhesive layer to remove the optical adhesive layer and the bonding layer.

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