Patent Publication Number: US-2023154903-A1

Title: Light-emitting diode (led) chip assembly and prepraing method thereof, and preparing method of display panel

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/130962, filed Nov. 16, 2021, the entire disclosure of which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to the field of display, and in particular to a light-emitting diode (LED) chip assembly and a preparing method thereof, and a preparing method of a display panel. 
     BACKGROUND 
     After a micro light-emitting diode (Micro-LED) is prepared on a wafer, the Micro-LED usually needs two or more transfers to be bonded to a drive backplane to realize preparation of a display panel. Due to a small size of the Micro-LED, mass transfer is needed, that is, a large number of chips are transferred to the drive backplane at one time. In some production scenarios, Micro-LEDs are required to be transferred up to 3×10 6  Micro-LEDs per hour. At present, many manufacturers choose to transfer the Micro-LEDs to the drive backplane by micro-transfer-printing (μTP) technology and van der Waals force. However, a transfer yield and a transfer efficiency of the μTP technology are not ideal. Therefore, how to quickly transfer the Micro-LEDs to the drive backplane is an urgent problem to be solved at present. 
     SUMMARY 
     In a first aspect, a LED chip assembly is provided in the present disclosure. The LED chip assembly includes a patterned substrate, a patterned support layer, and multiple LED chips. The patterned substrate defines multiple through holes. The patterned support layer is disposed on a surface of the patterned substrate and attached to the patterned substrate. Each LED chip at least partially extends into each through hole, the each LED chip is partially embedded in the patterned support layer, and the each LED chip has a face surface away from the patterned support layer. The patterned support layer defines a hollow structure which is at a position opposite to a back surface of the each LED chip and is for an operation body to extend into the hollow structure and touch the each LED chip, to apply a pressure to the each LED chip to make the each LED chip fall off the patterned support layer and out of the each through hole. When the each LED chip is fixed to a drive backplane, the face surface is a surface of the each LED chip facing the drive backplane and the back surface is a surface of the each LED chip away from the drive backplane. 
     In a second aspect, a preparing method of a LED chip assembly is further provided in the present disclosure. The preparing method includes the following. A carrier substrate with multiple LED chips and a temporary transfer substrate with multiple grooves are provided, the temporary transfer substrate includes a patterned substrate with multiple through holes and a temporary base plate which are laminated, and each groove is defined by each through hole. Each bonding pad is disposed on a face surface of each LED chip, the face surface is a surface of the each LED chip facing a drive backplane when the each LED chip is fixed to the drive backplane, and the face surface of the each LED chip is away from the carrier substrate. After the carrier substrate is aligned with the patterned substrate, at least part of the each LED chip is placed in the each through hole until the each bonding pad is bonded to a bottom of the each groove. After the carrier substrate is removed, a patterned support layer is disposed on a surface of the patterned substrate away from the temporary base plate, the patterned support layer is attached to the patterned substrate and the each LED chip, and the patterned support layer is hollow at a position opposite to the back surface of the each LED chip. The temporary base plate and bonding pads are removed to prepare the LED chip assembly. 
     In a third aspect, a preparing method of a display panel is further provided in the present disclosure. The preparing method includes the following. A drive backplane and a LED chip assembly are provided. The LED chip assembly includes a patterned substrate, a patterned support layer, and multiple LED chips. The patterned substrate defines multiple through holes. The patterned support layer is disposed on a surface of the patterned substrate and attached to the patterned substrate. Each LED chip at least partially extends into each through hole, the each LED chip is partially embedded in the patterned support layer, and the each LED chip has a face surface away from the patterned support layer. The patterned support layer defines a hollow structure which is at a position opposite to a back surface of the each LED chip and is for an operation body to extend into the hollow structure and touch the each LED chip, to apply a pressure to the each LED chip to make the each LED chip fall off the patterned support layer and out of the each through hole. When the each LED chip is fixed to the drive backplane, the face surface is a surface of the each LED chip facing the drive backplane and the back surface is a surface of the each LED chip away from the drive backplane. The drive backplane is aligned with the LED chip assembly, and the face surface of the each LED chip faces each chip reception area of the drive backplane. The operation body is controlled to extend into the hollow structure of the patterned support layer to abut against the back surface of the each LED chip, and the pressure is applied to the each LED chip until the each LED chip falls onto the each chip reception area. LED chips on chip reception areas are bonded to the drive backplane to prepare the display panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG.  1    is a schematic structural diagram of a light-emitting diode (LED) chip assembly provided in an optional implementation of the present disclosure. 
         FIG.  2    is a schematic top diagram of a patterned substrate provided in an optional implementation of the present disclosure. 
         FIG.  3    is a schematic diagram of using an operation body to lift off a LED chip from a LED chip assembly illustrated in an optional implementation of the present disclosure. 
         FIG.  4    is a schematic diagram of alignment of a LED chip assembly and a drive backplane illustrated in an optional implementation of the present disclosure. 
         FIG.  5    is a schematic diagram of alignment of another LED chip assembly and a drive backplane illustrated in an optional implementation of the present disclosure. 
         FIG.  6    is a schematic diagram of a positional relationship between a patterned support layer and LED chips illustrated in an optional implementation of the present disclosure. 
         FIG.  7    is a schematic diagram of another positional relationship between a patterned support layer and LED chips illustrated in an optional implementation of the present disclosure. 
         FIG.  8    is a schematic flowchart of a preparing method of a display panel provided in an optional implementation of the present disclosure. 
         FIG.  9    is a schematic diagram of process-state changes of preparation of a display panel provided in an optional implementation of the present disclosure. 
         FIG.  10    is a schematic flowchart of a preparing method of a LED chip assembly provided in another optional implementation of the present disclosure. 
         FIG.  11    is a schematic diagram of process-state changes of preparation of a LED chip assembly provided in another optional implementation of the present disclosure. 
         FIG.  12    is a schematic diagram of process-state changes of a temporary transfer substrate provided in another optional implementation of the present disclosure. 
         FIG.  13    is a schematic top diagram of a LED chip assembly provided in another optional implementation of the present disclosure. 
         FIG.  14    is a schematic top diagram of a LED chip assembly provided in yet another optional implementation of the present disclosure. 
         FIG.  15    is a schematic flowchart of a preparing method of a display panel provided in another optional implementation of the present disclosure. 
         FIG.  16    is a schematic diagram of process-state changes of preparation of a display panel provided in another optional implementation of the present disclosure. 
         FIG.  17    is a schematic diagram of process-state changes of preparation of LED chips provided in another optional implementation of the present disclosure. 
     
    
    
     Reference signs in the accompanying drawings are illustrated as follows: 
       10 —LED chip assembly;  11 —patterned substrate;  110 —through hole;  12 —patterned support layer;  120 —operation hole;  13 —LED chip;  30 —LED chip assembly;  31 —drive backplane;  32 —bonded LED chip;  61 —LED chip assembly;  62 —drive backplane;  63 —operaion body;  620 —chip reception area;  81 —carrier substrate;  82 —temporary transfer substrate;  820 —groove;  821 —temporary base plate;  822 —bonding layer;  823 —bonding pad;  1201 —growth base plate;  1202 —epitaxial layer;  1203 —indium tin oxide (ITO) pattern;  1204 —distributed Bragg reflector (DBR) pattern;  1205 —chip electrode;  1206 —LED chip;  1207 —temporary base plate;  1208 —patterned substrate;  1209 —through hole;  1210 —benzocyclobutene (BCB) bonding adhesive layer;  1211 —BCB bonding pad;  1212 —silicon dioxide (SiO 2 ) layer;  1213 —operation hole;  1214 —LED chip assembly;  1215 —drive backplane;  1216 —ejector pin. 
     DETAILED DESCRIPTION 
     In order to facilitate understanding of the present disclosure, a comprehensive description will be given below with reference to relevant accompanying drawings. The accompanying drawings illustrate some exemplary implementations of the present disclosure. However, the present disclosure can be implemented in many different forms and is not limited to the implementations described herein. On the contrary, these implementations are provided for a more thorough and comprehensive understanding of the present disclosure. 
     Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art of the present disclosure. The terms used herein in the specification of the present disclosure are for the purpose of describing specific implementations only and are not intended to limit the present disclosure. 
     A micro light-emitting diode (Micro-LED) technology refers to a LED array with a micro size and integrated with high density on a drive backplane, which reduces displayed pixels from a millimeter level to a micrometer level. Compared with a traditional display technology, the Micro-LED has obvious advantages, and the Micro-LED has characteristics of high brightness, high efficiency, high reliability, and fast response time. In addition, electroluminescence, a small size, and other characteristics also make the Micro-LED more widely used. 
     However, due to lack of an excellent scheme for transferring Micro-LED chips to the drive backplane, production efficiency of a display panel is seriously affected and development of the Micro-LED technology is seriously restricted. 
     Based on this, the present disclosure hopes to provide a solution to the above technical problems, details of which will be expounded in subsequent implementations. 
     In an optional implementation of the present disclosure, a LED chip assembly is provided in the implementation first, and reference can be made to  FIG.  1   , which is a schematic structural diagram of a LED chip assembly  10 . The LED chip assembly  10  includes a patterned substrate  11 , a patterned support layer  12 , and multiple LED chips  13 . 
     In the implementation, each LED chip  13  may be the above Micro-LED chip, a Min-LED chip, or a LED chip with a larger size. In some examples of the implementation, the each LED chip  13  may also be an organic light-emitting diode (OLED) chip. In addition, a structural type and a color type of the each LED chip  13  are also not limited in the implementation. The each LED chip  13  may have a flip-chip structure, a face-up structure, a vertical structure, or a horizontal structure. The LED chip  13  may be a three-primary-colors (red, green, and blue) chip, or a LED chip of a color other than three primary colors. 
     Due to different settings of light-emitting surfaces and chip electrodes of LED chips of different structural types, an orientation of LED chips of the same structural feature is difficult to represent orientations of LED chips of different types. Therefore, in order to facilitate a later introduction of setting of the each LED chip  13  in the LED chip assembly  10 , in the implementation, a “face surface” and a “back surface” of the each LED chip  13  are defined according to an orientation when the each LED chip  13  is fixed to the drive backplane. The face surface refers to a surface of the each LED chip  13  facing the drive backplane after the each LED chip  13  is bonded to the drive backplane, while the back surface refers to a surface of the each LED chip  13  away from the drive backplane after the each LED chip  13  is bonded to the drive backplane, that is, the surface of the each LED chip  13  opposite to the face surface. For example, a face surface of a LED chip with a flip-chip structure is a surface where chip electrodes are located, while a back surface is a main light-emitting surface of the LED chip with the flip-chip structure. However, in a LED chip with a face-up structure, a back surface of the LED chip with the face-up structure is a surface where chip electrodes are located, while a face surface is a surface opposite to the surface where the chip electrodes are located. 
     A patterned substrate  11  defines multiple through holes  110 , and there is no doubt that each through hole  110  is a hole penetrating through upper and lower surfaces of the patterned substrate  11 . Reference can be made to  FIG.  2   , which is a schematic top diagram of the patterned substrate  11 . The multiple through holes  110  are arranged in an array on the patterned substrate  11 , but it can be understood by those skilled in the art that in other examples, arrangement of through holes  110  may also adopt other schemes. However, since the each LED chip  13  will be supported in the each through hole  110 , the arrangement of the through holes  110  on the patterned substrate  11  will affect arrangement of LED chips  13 , while usually, the LED chips  13  in the LED chip assembly  10  will be directly transferred to the drive backplane. Therefore, in some examples, the arrangement of the through holes  110  on the patterned substrate  11  will follow arrangement of chip reception areas on the drive backplane. In addition, since the LED chips  13  in the LED chip assembly  10  are directly transferred from a carrier substrate (e.g., a growth substrate), the arrangement of the through holes  110  on the patterned substrate  11  will also follow arrangement of the LED chips  13  on the carrier substrate. In addition, the each through hole  110  in  FIG.  2    has a rectangular cross section, but a shape of the each through hole  110  is not limited in the implementation. For example, the cross section of the each through hole  110  may also be a circular, an ellipse, a parallelogram, etc., as long as the each through hole  110  can make the each LED chip  13  pass from one side to another side in a posture of the face surface being parallel to a flat surface of the patterned substrate  11 . 
     It can be understood that the patterned substrate  11  has a certain thickness, therefore, the each through hole  110  is actually equivalent to a channel for the each LED chip  13  to pass through. When the each LED chip  13  passes through the channel, a size of a cross section of the each through hole  110  determines a maximum movable range of the each LED chip  13  in a direction parallel to the patterned substrate  11 . In the implementation, in order to prevent the each LED chip  13  from having a large positional shift and turnover during passing through the each through hole  110 , the cross section of the each through hole  110  will be made relatively small. For example, in some examples of the implementation, the cross section of the each through hole  110  is only slightly larger than a cross section of the each LED chip  13 . 
     On one hand, the patterned support layer  12  is attached to the patterned substrate  11 , on the other hand, the patterned support layer  12  is also attached to the each LED chip  13 , such that part of the each LED chip  13  is embedded into the patterned support layer  12 , and another side of the each LED chip  13  can also be suspended in the each through hole  110  without any support, as illustrated in  FIG.  1   . In the implementation, the patterned support layer  12  is disposed on a surface of the patterned substrate  11 , and the surface is a surface where the back surface of the each LED chip  13  is located. In other words, the patterned support layer  12  is disposed at a side where the back surface of the each LED chip  13  is located, and the face surface of the each LED chip  13  is away from the patterned support layer  12 . 
     In the implementation, when the each LED chip  13  is suspended in the each through hole  110 , at least part of the back surface of the each LED chip  13  is exposed beyond the patterned support layer  12 . Therefore, the patterned support layer  12  defines a hollow structure at a position opposite to the back surface of the each LED chip  13 . In this way, when the each LED chip  13  needs to be lifted off from the LED chip assembly  10 , an operation body (such as an ejector pin, etc.) can extend into the hollow structure of the patterned support layer  12  and touch the back surface of the each LED chip  13 . Therefore, when the operation body applies a pressure to the back surface of the each LED chip  13 , the each LED chip  13  will move away from the patterned support layer  12 , thereby falling off the patterned support layer  12  and leaving the LED chip assembly  10  through another side of the each through hole  110  (that is, a side opposite to a side where the patterned support layer  12  is located), as illustrated in  FIG.  3   . 
     In some examples of the implementation, hollow structures of the patterned support layer  12  at positions opposite to back surfaces of different LED chips  13  communicate with each other, that is, the hollow structures in the patterned support layer  12  where the different LED chips  13  communicate with each other. In other examples, hollow structures in the patterned support layer  12  where the each LED chip  13  is located are independent from each other. In some examples, each operation hole  120  is defined in the patterned support layer  12  at the position opposite to the back surface of the each LED chip  13 . For example, in  FIG.  1   , the each operation hole  120  is accessible to the operation body such as the ejector pin, etc. Generally, a cross section of the each operation hole  120  is smaller than the back surface of the each LED chip. It can be understood that when the each operation hole  120  is smaller, the back surface of the each LED chip  13  is difficult to be contacted by an ordinary object through the each operation hole  120 , so as to prevent the each LED chip  13  from falling off the LED chip assembly  10  due to extrusion of an external object during removal and transportation of the LED chip assembly  10 . In the meantime, a size of the each operation hole  120  will not affect penetration of the operation body specially configured to lift off the each LED chip  13 . Therefore, when the each LED chip  13  in the LED chip assembly  10  needs to be transferred to the drive backplane, the each LED chip  13  can be easily lifted off by means of a special operation body such as the ejector pin, etc., which is conductive to improving quality and reliability of the LED chip assembly  10 . In other examples of the implementation, the cross section of the each operation hole  120  can also be greater than or equal to the back surface of the each LED chip  13 . For example, in an example of the implementation, the patterned support layer  120  is attached to all of four side surfaces of the each LED chip  13 , but is not attached to the back surface of the each LED chip  13 , such that an area of the cross section of the each operation hole  120  is equal to an area of the back surface. In another example, the patterned support layer  120  is only attached to one or two side surfaces of the each LED chip  13 , and certain gaps are defined between other two side surfaces of the each LED chip  13  and the patterned support layer  12 . In this case, the area of the each operation hole  120  will be greater than the area of the back surface of the each LED chip  13 . 
     A shape of the cross section of the each operation hole  120  includes, but is not limited to, a circle, an ellipse, a diamond, a triangle, a rectangle, etc. In addition, the shape of the cross section of the each operation hole  120  may also be a trapezium, a pentagram, or other regular or irregular shapes. 
     It can be understood that generally, when the LED chips are transferred to the drive backplane to prepare the display panel, all LED chips required on the drive backplane are not transferred in place at one time. For example, generally, LED chips of different colors will be transferred to the drive backplane in batches, and even LED chips of the same color are likely to be transferred in multiple batches. In this way, when some LED chips are transferred to the drive backplane, bonded LED chips have existed on the drive backplane. In addition, during LED chip repair, when a LED chip for repair is transferred to a position where the drive backplane needs to be repaired, the drive backplane has also been provided with abundant LED chips at other positions. In this case, if LED chips  13  are directly lifted off from the LED chip assembly to the drive backplane, some LED chips  13  will correspond to bonded LED chips  32  on the drive substrate after the LED chip assembly is aligned with the drive backplane. If a distance between a face surface of each LED chip  13  in a LED chip assembly  30  and a surface of the patterned substrate  11  facing the drive backplane  31  is too small, such as less than a height of each bonded LED chip  32  on the drive backplane  31 , a distance between the LED chip assembly  30  and the drive backplane  31  will be interfered by the height of the each bonded LED chip  32 , as illustrated in  FIG.  4   . In this case, the LED chip  13  lifted off from the LED chip assembly  30  cannot directly reach the drive backplane  31  after passing through the each through hole  110  in the patterned substrate  11 , but needs to continue to fall for a distance. Within the distance, since the LED chip is not limited by the through hole  110 , the LED chip  13  may shift, overturn, etc., which will affect the transfer yield of the LED chips  13  in LED chip assembly  30 . Therefore, in order to avoid an effect of the height of the each bonded LED chip  32  on the drive backplane  31  on the distance between the LED chip assembly and the drive backplane, and improve the transfer yield of the LED chips in the LED chip assembly, in some LED chip assemblies provided in the implementation, such as in the LED chip assembly  10 , the distance between the face surface of the each LED chip  13  and the surface of the patterned substrate  11  facing the drive backplane (i.e., a surface of the patterned substrate  11  away from the patterned support layer  12 ) is greater than the height of the each LED chip  13 . In this way, even if bonded LED chips have existed on the drive backplane, free space in the each through hole  110  of the patterned substrate  11  is sufficient to accommodate the each bonded LED chip  32 , as illustrated in  FIG.  5   . 
     In some examples of the implementation, the patterned support layer  12  may only be attached to the back surface of the each LED chip  13 , as illustrated in  FIG.  6   . In other examples, the patterned support layer  12  may only be attached to one or more side surface of the each LED chip  13 , but not attached to the back surface of the each LED chip  13 , as illustrated in  FIG.  7   . In addition, the patterned support layer  12  may be attached to both the back surface and side surfaces of the each LED chip  13 , as illustrated in  FIG.  1   . In some examples of the implementation, the patterned support layer  12  may only be located at one side of the patterned substrate  11 , but not be embedded in the through hole  110 . In other examples, the patterned support layer  12  may also be attached to the surface of the patterned substrate  11  while being partially embedded in the each through hole  110 . In some examples of the implementation, the back surface of the each LED chip  13  protrudes from the surface of the patterned substrate  11 , as illustrated in  FIG.  7    and  FIG.  1   . In other examples, the back surface of the each LED chip  13  may be flush with the surface of the patterned substrate  11 , and reference can continue to be made to  FIG.  6   . In some implementations, the back surface of the each LED chip  13  may also be located in the each through hole  110 . 
     Generally, the patterned support layer  12  does not have a deformation ability or has a poor deformation ability, which can avoid a problem that when the LED chip  13  tends to move away from the patterned support layer  12  due to the pressure of the operation body, the patterned support layer  12  continues to follow the LED chip  13  through deformation, resulting in a difficulty of separating the each LED chip  13  from the patterned support layer  12 . A material with no deformation ability or the poor deformation ability is selected to form the patterned support layer  12 , which can ensure that when the LED chip  13  tends to move away from the patterned support layer  12  due to the pressure of the operation body, the patterned support layer  12  is unable to be deformed and has to be separated from the each LED chip  13 , such that the LED chip  13  can fall off the patterned support layer  12  cleanly. Therefore, in the implementation, the patterned support layer  12  may be made of a brittle material, and failure stress of the patterned support layer  12  is lower or much lower than a yield limit of the material. In some examples of the implementation, a material of the patterned support layer  12  includes, but is not limited to, silicon oxide (SiO 2 ), graphite, and metal (including metal with a high carbon content, such as pig iron, etc.). 
     In order to make those skilled in the art clearer about an application process of lift off of the each LED chip in the LED chip assembly, a flow of preparation of the display panel by using the LED chip assembly is described below with reference to  FIG.  8    and  FIG.  9   . 
     At block  502 , a drive backplane and the above LED chip assembly are provided. 
     A LED chip assembly  61  provided in the implementation is the LED chip assembly  10  illustrated in  FIG.  1   , as illustrated in (a) in  FIG.  9   . However, it can be understood by those skilled in the art that the LED chip assembly  10  may also be other LED chip assemblies introduced in the above examples. 
     The drive backplane  62  includes multiple backplane electrodes on a chip carrier surface, two of these backplane electrodes are in a group to form a backplane electrode group, and an area where the backplane electrode group is located is one chip reception area  620 , which needs to receive the LED chip  13  from the LED chip assembly  61 . 
     At block  504 , the drive backplane is aligned with the LED chip assembly, and the face surface of the each LED chip faces each chip reception area of the drive backplane. 
     After the drive backplane  62  and the LED chip assembly  61  are obtained, the drive backplane  62  can be aligned with the LED chip assembly  61 . The each LED chip  13  needs to fall on the drive backplane  62  by gravity after the each LED chip  13  is pushed downwards to fall off the patterned support layer  12  by the operation body in a subsequent process, so when the drive backplane  62  is aligned with the LED chip assembly  61 , the LED chip assembly  61  needs to be ensured to be on the top and the drive backplane  62  needs to ensure to be at the bottom, as illustrated in (b) of  FIG.  9   . In addition, the each LED chip  13  in the LED chip assembly  61  should be aligned with the each chip reception area  620  on the drive backplane  62 . For example, the each LED chip  13  has a flip-chip structure, chip electrodes of the each LED chip  13  should be aligned with backplane electrodes of the drive backplane  62 , which can ensure that the each LED chip  13  directly fall onto the each chip reception area  620  after the each LED chip  13  is separated from the patterned support layer  12 , and ensure that the each LED chip  13  can be successfully bonded to the each chip reception area  620  on the basis of avoiding subsequent adjustment of a position of the each LED chip  13  on the drive backplane  62 , thereby not only simplifying a process of transfer-and-bonding of the each LED chip  13 , but also improving yield of transfer-and-bonding of the LED chips  13 . 
     It can be understood that the each through hole  110  in the patterned substrate  11  can limit a shift of the each LED chip  13  in a horizontal direction and prevent turnover of the each LED chip  13  when the each LED chip  13  falls onto the drive backplane  62 . However, after the each LED chip  13  passes through the each through hole  110 , the shift and turnover may also occur. Therefore, in the implementation, after the LED chip assembly  61  is aligned with the drive backplane  62 , a surface of the LED chip assembly  61  facing the drive backplane  62  can be directly attached to the drive backplane  62 , such that the each LED chip  13  can fall on the drive backplane  62  without even passing through the each through hole  110 , and no shift and turnover occur. 
     At block  506 , the operation body is controlled to extend into the hollow structure of the patterned support layer to abut against the back surface of the each LED chip, and a pressure is applied to the each LED chip until the each LED chip falls onto the each chip reception area. 
     After a relative position of the drive backplane  62  and the LED chip assembly  61  is set, an operation body  63  can be controlled to extend into the hollow structure of the patterned support layer  12 . There is no doubt that since the patterned support layer  12  is located on a side where the back surface of the each LED chip  13  is located, the operation body extending into the hollow structure can only abut against the back surface of the each LED chip  13 , as illustrated in (c) of  FIG.  9   . After touching the back surface of the each LED chip  13 , the operation body  63  can apply the pressure to the each LED chip  13  as illustrated in (d) of  FIG.  9   , such that the each LED chip  13  moves away from the patterned support layer  12  until the each LED chip  13  falls off the patterned support layer  12  to the each chip reception area  620  on the drive backplane  61 , and the drive backplane  61  can provide the each LED chip  13  with a support force to balance gravity of the each LED chip  13 . 
     At block  508 , LED chips on chip reception areas are bonded to the drive backplane to prepare the display panel. 
     After the each LED chip  13  falls onto the each chip reception area  620  on the drive backplane  61 , the each LED chip  13  can be bonded to the drive backplane  62 , as illustrated in (e) of  FIG.  9   . It can be understood that bonding the each LED chip  13  to the drive backplane  62  not only includes fixing the each LED chip  13  to the drive backplane  62  to realize a physical connection between the each LED chip  13  and the drive backplane  62 , but also includes realizing electrical coupling of the each LED chip  13  and the drive backplane  62 . For example, the each LED chip  13  has the flip-chip structure. In the implementation, before the each LED chip  13  is lifted off from the LED chip assembly  61 , a bonding material can be set on the backplane electrodes of the drive backplane  62  or the chip electrodes of the each LED chip  13  first, such that when the each LED chip  13  falls onto the drive backplane  62 , bonding can be directly realized. Optionally, the bonding material includes, but is not limited to, solder, such as eutectic gold/tin (Au/Sn), tin solder, etc., and a conductive adhesive material, such as silver conductive adhesive, anisotropic conductive film (ACF), etc. 
     It can be understood that multiple LED chips  13  in the LED chip assembly  61  can be lifted off to the drive backplane  62  simultaneously. For example, multiple ejector pins push different LED chips downwards to fall, such that efficiency of transfer-and-bonding of the LED chips  13  can be improved. In addition, generally, some LED chips  13  bonded to the drive backplane  62  may be defective. Therefore, after the each LED chip  13  is bonded to the drive backplane  62 , defective LED chips on the drive backplane  62  can be identified by detection and removed from the drive backplane  62 , and then a LED chip assembly for repair is provided. The LED chip assembly for repair may also be the LED chip assembly  10  provided in the above examples. After the LED chip assembly for repair is aligned with the drive backplane  62 , according to positions of the defective LED chips in the drive backplane  62 , operation bodies are controlled to push LED chips which are for repair and at corresponding positions of the LED chip assembly for repair downwards. After the LED chips for repair are pushed downwards to the drive backplane  62 , these LED chips can be bonded to the drive backplane  62  to realize LED chip repair. Defective LED chips may still exist after repair, so detection and repair need to be performed continually until no defective LED chips exist on the drive backplane  62 . There is no doubt that during the LED chip repair, the operation body will not apply pressure to other LED chips in the LED chip assembly for repair except the LED chips for repair. 
     In a preparing method of the LED chip assembly and a preparing method of the display panel provided in the implementation, the each LED chip in the LED chip assembly is supported in the each through hole through the patterned support layer. Therefore, when the display panel is required to be prepared, the LED chip assembly is just required to be aligned with the drive backplane, and the each LED chip is pushed downwards through the operation body such as the ejector pin, etc., such that the each LED chip can fall onto the each chip reception area of the drive backplane. In addition, since limit and block of the each through hole can prevent the each LED chip from shifting and overturning in the process of transfer of the each LED chip to the drive backplane, not only can the transfer efficiency of the LED chips be improved, but also the transfer yield can be increased and preparation costs of the display panel can be reduced. 
     In another optional implementation of the present disclosure, a preparing method of the above LED chip assembly is provided in the implementation, and reference can be made to  FIG.  10    and  FIG.  11   . 
     At block  702 , a carrier substrate with multiple LED chips and a temporary transfer substrate with multiple grooves are provided. 
     Reference can be made to (a) in  FIG.  11   . In the implementation, a carrier substrate  81  is provided with multiple LED chips  13 , and each LED chip  13  has a back surface facing the carrier substrate  81 , that is, an orientation of the each LED chip  13  on the carrier substrate  81  is opposite to an orientation of the each LED chip  13  on drive backplane. For example, the each LED chip has a flip-chip structure, and when a flip LED chip is located on the drive backplane, chip electrodes of the flip LED chip faces the drive backplane, but when the flip LED chip is on the carrier substrate  81 , the chip electrodes of the flip LED chip is away from the carrier substrate  81 . In the implementation, the carrier substrate  81  may be a growth substrate of the each LED chip  13 . For example, when the each LED chip  13  is a blue-light chip or a green-light chip, the carrier substrate  81  may be a sapphire substrate, a silicon substrate, or a gallium nitride (GaN) substrate where a blue-green epitaxial layer grows. In the implementation, the carrier substrate  81  is not excluded to be a substrate configured to carry the each LED chip  13  after growth of the each LED chip  13 , that is, a transient substrate (also known as “temporary substrate”, “transfer substrate”, etc.). 
     A temporary transfer substrate  82  defines multiple grooves  820 . Each groove  820  is actually a non-penetrating “blind hole” relative to the temporary transfer substrate  82 . In the implementation, the temporary transfer substrate  82  includes a patterned substrate  11  with multiple through holes  110  and a temporary base plate  821  which are laminated. When an upper surface of the temporary base plate  821  is opposite to a lower surface of the patterned substrate  11 , and no gap is between the upper surface of the temporary base plate  821  and the lower surface of the patterned substrate  11 , a lower end of each through hole  110  will be sealed by a surface of the temporary base plate  821  to define the each groove  820 . It should be understood that since the temporary transfer substrate  82  is formed by attachment of the temporary base plate  821  and the patterned substrate  11  which are independent from each other, the temporary base plate  821  and patterned substrate  11  which are in the temporary transfer substrate  82  can also be separated from each other when necessary. 
     In some examples of the implementation, the temporary transfer substrate  82  further includes a bonding layer  822 , and reference can be made to  FIG.  12   , which is a schematic diagram of process-state changes of preparation of a temporary transfer substrate  82 . In (a) of  FIG.  12   , a temporary base plate  821  and a patterned substrate  11  are provided. Then, as illustrated in (b) of  FIG.  12   , after the temporary base plate  821  is aligned with the patterned substrate  11 , the temporary base plate  821  is attached to the patterned substrate  11  through the bonding layer  822  between the temporary base plate  821  and the patterned substrate  11 . In some examples of the implementation, the bonding layer  822  can be formed on other substrates in advance, and then transferred to a surface of the temporary base plate  821  facing the patterned substrate  11  or to a surface of the patterned substrate  11  facing the temporary base plate  821 . In other examples, the bonding layer  822  can be temporarily formed on the surface of the temporary base plate  821  facing the patterned substrate  11  or on the surface of the patterned substrate  11  facing the temporary base plate  821 . 
     In some examples of the implementation, the temporary base plate  821  and the patterned substrate  11  can be bonded together by bonding, so the bonding layer  822  may be a bonding adhesive layer, such as a benzocyclobutene (BCB) adhesive layer, a thermal release tape layer, etc. For example, the bonding adhesive layer is disposed on the surface of the temporary base plate  821  facing the patterned substrate  11 , and the patterned substrate  11  is fixed to the temporary base plate  821  through the bonding adhesive layer. In some examples, a shape of a surface of the bonding adhesive layer is consistent with a shape of the surface of the patterned substrate  11 , that is, the bonding adhesive layer defines each hollow structure at a position opposite to the each through hole  110  in the patterned substrate  11 . In other examples, a shape of a surface of the bonding adhesive layer is consistent with a shape of the surface of the temporary base plate  821 , and no hollow structure exists, as illustrated in (b) of  FIG.  12   . Therefore, the bonding adhesive layer is also exposed beyond at the bottom of the each groove  820 . In other examples of the implementation, the temporary base plate  821  and the patterned substrate  11  can also be bonded by other methods, such as eutectic bonding, van der Waals force bonding, etc. 
     At block  704 , each bonding pad is disposed on a face surface of each LED chip. 
     After the carrier substrate  81  with the multiple LED chips  13  is obtained, each bonding pad  823  can be disposed on a face surface of the each LED chip  13 , as illustrated in (b) of  FIG.  11   . The each bonding pad  823  is mainly configured to bond the each LED chip  13  on the carrier substrate  81  to the bottom of the each groove  820  of the temporary transfer substrate  82 , such that after the carrier substrate  81  is lifted off, the each LED chip  13  can be stabilized in the each groove  820  without support of the carrier substrate  81 . 
     In some examples of the implementation, the each bonding pad may a sticky adhesive block, such as a BCB adhesive block, such that the each bonding pad  823  can bond and fix the each LED chip  13  at the bottom of the each groove  820 . When the each bonding pad  823  is disposed, the liquid adhesive material can be coated on the face surface of the each LED chip  13 . After the liquid adhesive material is cured, the each bonding pad  823  bonded to the face surface of the each LED chip  13  can be formed. 
     It can be understood that in some examples, the each groove  820  is provided with a bonding adhesive layer at the bottom of the each groove. Therefore, even if the each bonding pad  823  itself does not have stickiness, it is also feasible that as long as the each bonding pad  823  is attached to the each LED chip  13  and the each bonding pad  823  is in contact with the bonding adhesive layer at the bottom of the each groove  820  at the same time, because the bonding adhesive layer can be bonded to the each bonding pad  823 , thus, the each LED chip  13  fixed to the each bonding pad  823  is fixed in the each groove  820 . 
     At block  706 , after the carrier substrate is aligned with the patterned substrate, at least part of the each LED chip is placed in the each through hole until the each bonding pad is bonded to a bottom of the each groove. 
     After the each bonding pad  823  is disposed on the face surface of the each LED chip  13 , the carrier substrate  81  can be aligned with the patterned substrate  11 , and the face surface of the each LED chip  13  faces a groove bottom of the each groove  820 , as illustrated in (c) of  FIG.  11   . Then, the carrier substrate  81  can continue to move relative to the temporary transfer substrate  82  until the each bonding pad  823  is bonded to the bottom of the each groove  820 , as illustrated in (d) of  FIG.  11   . 
     At block  708 , after the carrier substrate is removed, a patterned support layer is disposed on a surface of the patterned substrate away from the temporary base plate. 
     After the each LED chip  13  on the carrier substrate  81  is bonded to the bottom of the each groove  820  through the each bonding pad  823 , the carrier substrate  81  can be removed, as illustrated in (E) of  FIG.  11   . In some examples, the each LED chip  13  can be separated from and the carrier substrate  81  by laser lift off (LLO). For example, the each LED chip  13  is a GaN-based chip, and the carrier substrate  81  is the growth substrate of the each LED chip  13 . When the carrier substrate  81  is lifted off, an interface between the carrier substrate  81  and the each LED chip  13  is irradiated by laser, causing a reaction of GaN→Ga+N 2  at the interface, thereby destroying attachment between the carrier substrate  81  and the each LED chip  13  and realizing removal of the carrier substrate  81 . 
     After the carrier substrate  81  is removed, a patterned support layer  12  can be disposed on a surface of the patterned substrate  11  away from the temporary base plate  821 , as illustrated in (f) of  FIG.  11   , that is, the patterned support layer  12  is disposed at a side where the back surface side of the each LED chip  13  is located. A disposed patterned support layer  12  is not only attached to the patterned substrate  11 , but also is attached to the each LED chip  13 , such that the patterned support layer  12  can fix a position of the each LED chip  13  in the each through hole  110  at the back surface of the each LED chip  13 , so as to ensure that after support of the temporary base plate  821  is removed, the each LED chip  13  can continue to be kept in the same position in the each through hole  110  as before the temporary base plate  821  is removed. 
     As the name suggests, the patterned support layer  12  has a patterned layer structure. In the implementation, a main reason that the patterned layer structure is required is that at least part of the back surface of the each LED chip  13  facing the patterned support layer  12  is exposed beyond the patterned support layer  12 , that is, the patterned support layer  12  is ensured to not cover all the back surface of the each LED chip  13 , so as to ensure that an external operation body can directly touch the back surface of the each LED chip  13  in a subsequent process. Therefore, in the implementation, the patterned support layer  12  defines the hollow structure at the position opposite to the back surface of the each LED chip  13 . 
     It can be seen from the introduction of the above implementations that hollow structures  100   a  in the patterned support layer  12  where the different LED chips  13  are located can communicate with each other. For example, reference can be made to  FIG.  13   , which is a schematic top diagram of a LED chip assembly  10   a . In addition, in other examples, hollow structures  100   b  in the patterned support layer  12  where different LED chips  13  of the LED chip assembly are located can also be independent from each other, for example, a LED chip assembly  10   b  as illustrated in  FIG.  14   . When hollow structures are independent from each other, each operation hole  120  is defined at a position corresponding to a back surface of each LED chip  13  on the patterned support layer  12 , and the each operation hole  120  is used for the operation body to extend into and apply the pressure to the each LED chip  13  to push the each LED chip  13  downwards. 
     In the implementation, the patterned support layer  12  is made of a brittle material, such as silicon oxide or metal. In other examples of the implementation, the patterned support layer  12  may be made of a relatively brittle adhesive material after curing. In some examples, a support material which forms the patterned support layer  12  can be disposed on the patterned substrate  11  by physical vapor deposition (PVD), chemical vapor deposition (CVD), vacuum evaporating (EV), etc. 
     It can be understood that in order to obtain the patterned layer structure, the support material can be deposited on a side of the patterned substrate  11  away from the temporary base plate  821  to form a complete support layer, then the support layer is patterned, and the support layer defines the hollow structure at the position opposite to the back surface of the each LED chip  13  by etching, so as to obtain the patterned support layer  12 . This method of disposing the patterned support layer  12  is more suitable for a scenario of disposing the patterned support layer  12  with silicon oxide as the support material, because if the support layer is made of metal, a temperature of etching metal may exceed a temperature that an epitaxial layer of the each LED chip  13  can withstand during etching the support layer, resulting in damage of the each LED chip  13  during patterning the support layer. 
     In other examples of the implementation, when the patterned support layer  12  is disposed, a mask pattern can also be disposed first, the make pattern covers at least part of the back surface of the each LED chip, and then the support material is disposed through the mask pattern. With protection of the mask pattern, some areas of the back surface of the each LED chip  13  will not be covered by the support material, so the patterned support layer  12  can be obtained after the mask pattern is removed. This disposing scheme of the patterned support layer  12  is applicable to a scenario of using metal as the support material, because this disposing scheme can avoid a problem of damage of the each LED chip  13  caused by etching the support layer with a relatively high etching temperature after a metal material is deposited. As for a scenario with silicon oxide as the support material, this disposing scheme is usually not selected because the mask pattern is usually unable to withstand an excessive high deposition temperature of silicon oxide. However, it can be understood by those skilled in the art that currently common mask patterns are formed by a photoresist, but if other high-temperature resistant mask materials can be found, the patterned support layer  12  of a silicon oxide material can also be disposed in this way. 
     At block  710 , the temporary base plate and bonding pads are removed to prepare the LED chip assembly. 
     After the patterned support layer  12  is disposed, a temporary base plate  821  and bonding pads  823  can be removed. Since the temporary base plate  821  and the patterned substrate  11  are bonded together, when the temporary base plate  821  is removed, a connection relationship between the temporary base plate  821  and the patterned substrate  11  needs to be destroyed first, such that the temporary base plate  821  can be separated from the patterned substrate  11 . In some examples of the implementation, the temporary base plate  821  is bonded to the patterned substrate through the bonding adhesive layer (such as the thermal release tape layer or the BCB adhesive layer), such that a bonding ability of the bonding adhesive layer can be reduced by heating, and then the temporary base plate  821  can fall off, as illustrated in (g) of  FIG.  11   . The bonding pads  823  can be removed by etching, laser, etc., as illustrated in (h) of  FIG.  11   . After the temporary base plate  821  and bonding pads  823  are removed, the LED chip assembly  10  can be obtained. 
     It is can be understood that the patterned substrate  11  in the LED chip assembly  10  can be recycled. For example, when all LED chips  13  in the LED chip assembly  10  are lifted off, the patterned support layer  12  attached to the patterned substrate  11  can be removed, and then the patterned substrate  11  can continue to be used to prepare a new temporary transfer substrate, thereby forming a new LED chip assembly, which can reduce preparation costs of the LED chip assembly  10 . 
     In the preparing method of the LED chip assembly provided in the implementation, the temporary transfer substrate with the multiple grooves is formed by the temporary base plate and the patterned substrate. In this case, the each bonding pad is disposed on the face surface of the each LED chip, and after the carrier substrate is aligned with the patterned substrate, the each LED chip is at least partially placed in the each through hole until the each bonding pad is bonded to the bottom of the each groove. Therefore, when the carrier substrate is lifted off, the each bonding pad can also support the each LED chip in the each through hole. In this case, the patterned support layer is disposed on the surface of the patterned substrate away from the temporary base plate. The patterned support layer will not only be attached to the patterned substrate, but also be attached to the each LED chip. Therefore, when the temporary transfer substrate and the each bonding pad are removed, the patterned support layer can provide force for the each LED chip to balance gravity of the each LED chip, such that the each LED chip can continue to be suspended in the each through hole. In the meanwhile, the patterned support layer is hollow at the position opposite to the back surface of the each LED chip, such that during the transfer of the each LED chip to the drive backplane, the external operation body can be ensured to extend into a hollow position and touch the each LED chip, to apply the pressure to the each LED chip to make the each LED chip fall off the patterned support layer under the pressure and out of the each through hole in the patterned substrate. Therefore, during the transfer of the each LED chip in the LED chip assembly to the drive backplane, as long as the LED chip assembly is aligned with the drive backplane and the face surface of the each LED chip faces the drive backplane, the each LED chip can be ensured to directly fall onto the each chip reception area of the drive backplane under the pressure of the operation body. The transfer process is simple and convenient. When the multiple operation bodies operate simultaneously, the multiple LED chips can be ensured to be transferred to the drive backplane simultaneously, such that the transfer efficiency of the multiple LED chips is improved. In addition, the process of the each LED chip falling is actually the process of the each LED chip passing through the each through hole, and when the each LED chip passes through the each through hole, the movement of the each LED chip in the horizontal direction will be limited by the side wall of the each through hole, such that the side wall of the each through hole can be used to limit the horizontal shift of the each LED chip during falling, the shift and turnover of the each LED chip can be reduced, the accuracy of the transfer position of the each LED chip can be improved, and the transfer yield of the LED chips can be improved. 
     In yet another implementation of the present disclosure, in order to make those skilled in the art clearer about details and advantages of the above LED chip assembly and the preparing method thereof, and the preparing method of the display panel, the implementation will continue to elaborate preparation and application of the LED chip assembly in combination with examples, and reference can be made to  FIG.  15    and  FIG.  16   . 
     At block  1102 , a growth base plate and an epitaxial layer grown on the growth base plate are provided. 
     In the implementation, the epitaxial layer  1202  may be a GaN-based blue-green epitaxial layer, and a growth base plate  1201  is a sapphire substrate. As illustrated in (a) of  FIG.  16   , the epitaxial layer  1202  is deposited on the growth base plate  1201 , and includes an N-type semiconductor layer (such as an N—GaN layer), an active layer, and a P-type semiconductor layer (such as a P—GaN layer) from bottom to top. It can be understood that the epitaxial layer  1202  includes but is not limited to these three layers, in addition, the epitaxial layer  1202  may also include at least one of a buffer layer, a stress-relief layer, an ohmic contact layer, and other layer structures. 
     At block  1104 , multiple LED chips are prepared based on the epitaxial layer. 
     As illustrated in (b) of  FIG.  16   , after the growth base plate  1201  with the epitaxial layer  1202  is obtained, multiple LED chips  1206  are prepared based on the epitaxial layer  1202 , and a process of preparing LED chips  1206  is elaborated below. 
     In (b) of  FIG.  17   , mesa etching is performed on the epitaxial layer  1202  provided in (a) of  FIG.  17   . An etching method is dry etching, and an etching gas may be at least one of boron trichloride (BCl 3 ) and chlorine (Cl 2 ). 
     In (c) of  FIG.  17   , trench etching continues to be performed on the epitaxial layer  1202  until the growth base plate  1201  is exposed. The etching method can also choose the dry etching, and the etching gas may be at least one of BCl 3  and Cl 2 . 
     In (d) of  FIG.  17   , an indium tin oxide (ITO) layer with a thickness of 200-2000 Å can be sputtered on the epitaxial layer  1202 , and then a mask pattern is formed on the ITO layer by using the photoresist, and an ITO pattern  1203  is obtained after performing wet etching on the ITO layer under cover of the mask pattern and photoresist stripping. 
     In (e) of  FIG.  17   , silicon oxide and silicon nitride are evaporated on the ITO pattern  1203  to form a distributed Bragg reflector (DBR), and the DBR has a thickness of 1˜4 μm; then, a mask pattern is formed on the DBR by using the photoresist, and subsequently the DBR is etched by the dry etching with at least one of carbon tetrafluoride (CF 4 ), oxygen (O 2 ), argon (Ar), and other etching gases, until the DBR is etched through. After the mask pattern is removed, a DBR pattern  1204  is obtained. 
     In (f) of  FIG.  17   , a negative photoresist is adopted to form a mask pattern on the DBR pattern  1204 , and the mask pattern is used to dispose a PAD (i.e., a chip electrode) of a LED chip  1206 , then an electrode layer is formed by evaporating electrode materials such as Fulin evaporation machine, and the electrode layer has a thickness of 1˜4 μm. After a blue film is lifted off and the photoresist is stripped, chip electrodes  1205  are obtained, and preparation of a LED chip  1206  is completed. 
     At block  1106 , a temporary base plate and a patterned substrate are manufactured into a temporary transfer substrate. 
     In the implementation, each of the temporary base plate  1207  and the patterned substrate  1208  can be made of a sapphire substrate, a glass substrate, a silicon substrate, etc. The patterned substrate  1208  defines multiple through holes  1209  arranged in an array. Arrangement of through holes  1209  on the patterned substrate  1208  is the same as arrangement of the LED chips  1206  on the growth base plate  1201 . Generally, each through hole  1209  has a cross section slightly larger than the each LED chip  1206 , such as 2˜5 μm larger. 
     Reference can be made to (c) of  FIG.  16   , the patterned substrate  1208  may have a horizontal dimension identical to the temporary base plate  1207 . For example, in an example, the temporary base plate  1207  and the patterned substrate  1208  each are 4 inches. The temporary base plate  1207  and the patterned substrate  1208  can be bonded together through a BCB bonding adhesive layer  1210 . In the implementation, the BCB bonding adhesive layer  1210  can be coated on a surface of the temporary base plate  1207 , and then the patterned substrate  1208  and the BCB bonding adhesive layer  1210  can be bonded together to realize bonding between the patterned substrate  1208  and the temporary base plate  1207 . After the patterned substrate  1208  and the temporary base plate  1207  are bonded, the temporary transfer substrate is prepared, as illustrated in (c) of  FIG.  16   . As can be seen from (c) of  FIG.  16   , the each through hole  1209  becomes a groove after the patterned substrate  1208  is bonded to the temporary base plate  1207 , and the BCB bonding adhesive layer  1210  is exposed beyond a bottom of the groove. 
     At block  1108 , a BCB adhesive is disposed at a chip-electrode side of each LED chip on the growth base plate to form each BCB bonding pad. 
     After the each LED chip  1206  is prepared on the growth base plate  1201 , the each bonding pad can be disposed on the face surface of the each LED chip  1206 . Since the each LED chip  1206  in the implementation has a flip-chip structure, the each bonding pad is disposed on the chip-electric side of the each LED chip  1206 . In addition, the each bonding pad in the implementation is formed by the BCB adhesive. Specifically, a liquid BCB adhesive can be coated on a side of the each LED chip away from the growth base plate  1201  to form the each BCB bonding pad  1211 , as illustrated in (d) of  FIG.  16   . 
     It can be understood that a process of disposing the each BCB bonding pad  1211  on the face surface of each LED chip  1206  may be completed immediately after preparation of the each LED chip  1206 , or may be executed after preparation of the temporary transfer substrate. It can be understood by those skilled in the art that no strict timing sequence exists between the process of disposing the each BCB bonding pad  1211  and a process of preparing the temporary transfer substrate. 
     At block  1110 , the each LED chip on the growth base plate is bonded to the temporary transfer substrate. 
     Subsequently, the growth base plate  1201  can be aligned with the temporary transfer substrate, and the each LED chip can at least partially extend into the each through hole  1209  until the each BCB bonding pad  1211  and BCB bonding adhesive layer  1210  are bonded together, as illustrated in (e) of  FIG.  16   . 
     At block  1112 , the growth base plate is lifted off by laser. 
     After the each LED chip  1206  is bonded to the groove, the growth base plate  1201  can be lifted off by laser, as illustrated in (f) of  FIG.  16   . 
     At block  1114 , a SiO 2  layer is deposited at a side of the patterned substrate away from the temporary base plate. 
     After the growth base plate  1201  is lifted off, a surface of the patterned substrate  1208  away from the temporary base plate  1207  is exposed. In this case, a SiO 2  layer  1212  can be deposited by plasma enhanced chemical vapor deposition (PECVD), and the SiO 2  layer  1212  will be attached to both an exposed back surface of the each LED chip  1206  and the surface of the patterned substrate  1208  away from the temporary base plate  1207 , as illustrated in (g) of  FIG.  16   . In some cases, the SiO 2  layer  1212  may also be embedded in the through holes  1209 . 
     At block  1116 , the SiO 2  layer  1212  is etched to define operation holes to obtain a patterned SiO 2  layer. 
     Since the SiO 2  layer  1212  disposed in (g) of  FIG.  16    completely covers the surface of the patterned substrate  1208  away from the temporary base plate  1207 , the back surface of the each LED chip  1206  is also all under the SiO 2  layer  1212 . In order to expose at least part of the back surface of the each LED chip  1206 , the SiO 2  layer  1212  will be etched in the implementation, so as to define each operation hole  1213  at a position opposite to the back surface of the each LED chip  1206 , as illustrated in (h) of  FIG.  16   . An aperture of the each operation hole  1213  is usually small, but can be passed by the operation body, such as the ejector pin. The SiO 2  layer  1212  can be etched by dry etching, and etching gases include, but are not limited to, silane and laughing gas (i.e., nitrous oxide). 
     It can be understood that in other examples of the implementations, a metal layer can also be adopted to replace the SiO 2  layer  1212 . However, if a metal layer is disposed, a mask pattern should be disposed before a metal material is deposited to avoid etching after arrangement of the metal layer. 
     At block  1118 , the temporary base plate is separated from the BCB adhesive by heating. 
     After the patterned SiO 2  layer  1212  is disposed, the temporary base plate  1027  can be lifted off. In the implementation, an adhesive force of the BCB adhesive can be reduced by heating, and then the temporary base plate  1207  can be separated from the BCB adhesive layer, as illustrated in (i) of  FIG.  16   . 
     At block  1120 , the BCB adhesive is removed by etching. 
     In the implementation, the BCB adhesive attached to the patterned substrate  1208  and the LED chip  1206  is also to be removed. Optionally, the BCB adhesive can be removed by the dry etching, as illustrated in (j) of  FIG.  16   . After the BCB adhesive is removed, the LED chip assembly  1214  is prepared. 
     At block  1122 , the drive backplane is aligned with the LED chip assembly, and the face surface of the each LED chip faces each chip reception area of the drive backplane. 
     After preparation of the LED chip assembly  1214 , the LED chip assembly  1214  can be applied. The each LED chip  1206  can be quickly and accurately transferred to the drive backplane through a structure of the LED chip assembly  1214 . Optionally, the drive backplane  1215  can be aligned with the LED chip assembly  1214 , and the face surface of the each LED chip  1206  can be kept facing each chip reception area of the drive backplane, as illustrated in (k) of  FIG.  16   . 
     At block  1124 , the operation body is controlled to extend into the each operation hole to abut against the back surface of the each LED chip, and a pressure is applied to the each LED chip until the each LED chip falls onto the each chip reception area. 
     Subsequently, the operation body, such as an injector pin  1216 , extends into each operation hole  1213  to abut against the back surface of the each LED chip  1206 , and apply pressure to the each LED chip  1206  until the each LED chip  1206  falls off the SiO 2  layer  1212  and falls onto the each chip reception area of the drive backplane  1215 , as illustrated in (1) of  FIG.  16   . 
     It can be understood that in the each LED chip  1206  with the flip-clip structure, the back surface is likely to have an area greater than the face surface, so an epitaxial layer of the each LED chip  1206  is inverted-trapezoid. In this case, when the each LED chip  1206  falls off the SiO 2  layer  1212 , the SiO 2  layer  1212  will fragment, and some fragmented SiO 2  layers  1212  will be attached to a LED chip  1206  and taken away by the LED chip  1206 . However, because the SiO 2  layer can passivate the LED chip  1206 , basically no negative impact will be on performance of the LED chip  1206 . 
     At block  1126 , LED chips on chip reception areas are bonded to the drive backplane to prepare a display panel. 
     After the each LED chip  1206  falls onto the drive backplane  1215 , the chip electrodes of the each LED chip  1206  can be bonded to the backplane electrodes on the drive backplane  1215  to realize transfer of the each LED chip  1206 , as illustrated in (m) of  FIG.  16   . 
     It can be understood that the LED chips  1206  transferred to the drive backplane  1215  may be chips with different colors, to facilitate preparation of a colorful display panel. 
     In the implementation, quick mass transfer of LED chips can be realized and transfer efficiency of the LED chips can be improved by the patterned substrate and the patterned support layer. In this case, the each through hole in the patterned substrate can prevent the each LED chip from shifting and overturning during the each LED chip falling onto the drive backplane, such that the transfer yield of the LED chips is improved. In addition, since the patterned substrate can be reused, the preparation costs of the display panel are reduced. 
     It should be understood that the application of the present disclosure is not limited to the above examples, and for those of ordinary skill in the art, improvements or modifications can be made according to the above descriptions, and all such improvements and modifications shall fall within the protection scope of the appended claims of the present disclosure.