Display backboard, preparation method thereof and display device

Abstract

The invention provides a display backboard, a preparation method thereof and a display device. The display backboard comprises a driving substrate; a plurality of driving electrodes on the driving substrate; the plurality of connecting structures are respectively arranged on the plurality of driving electrodes, and each connecting structure comprises at least one conductive part which is arranged on the corresponding driving electrode; and a restriction portion located on a side of the driving electrode on which the at least one conductive portion is provided and located in at least a partial peripheral region of the at least one conductive portion, the restriction portion protruding from the driving electrode and having a first height in a direction perpendicular to the driving substrate.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to international application No. PCT / CN2019 / 089543, filed on May 31, 2019, and international application No. PCT / CN2019 / 100920, filed on August 16, 2019, the entire disclosures of which are incorporated herein by reference. Technical Field

[0003] The present disclosure relates to the field of display technology, and in particular to a display backplane and a preparation method thereof, and a display device. Background Art

[0004] Micro-Light Emitting Diode (Micro-LED)

[0005] Micro-LED (or μLED) display technology is to shrink the size of existing LEDs to less than 100μm, which is about 1% of the size of existing LEDs. Through mass transfer technology, micron-scale RGB three-color Micro-LEDs are transferred to the driving substrate, thus forming Micro-LED displays of various sizes.

[0006] Each Micro-LED pixel can be addressed and driven to emit light individually, and the distance between adjacent pixels is reduced from millimeters to micrometers. Micro-LED has many advantages such as self-luminous high brightness, high contrast, ultra-high resolution and color saturation, long life, fast response speed, energy saving, and wide adaptability to the environment. Micro-LED display technology can cover the fields of micro-displays such as augmented reality (AR) or virtual reality (VR), medium-sized displays such as mobile TVs, and large-screen displays in theaters. Summary of the invention

[0007] According to one aspect of the present disclosure, a display backplane is provided, comprising: a driving substrate; a plurality of driving electrodes located on the driving substrate; a plurality of connecting structures, which are respectively located on the plurality of driving electrodes, and the orthographic projection of each of the plurality of connecting structures on the driving substrate is located within the orthographic projection of the corresponding driving electrode on the driving substrate, wherein the connecting structure comprises: at least one conductive portion, which is located on the driving electrode, and an area of ​​a first cross-section of the at least one conductive portion is negatively correlated with a distance between the first cross-section and a surface of the driving substrate, and the first cross-section is parallel to the surface of the driving substrate; and a limiting portion, which is located on a side of the driving electrode where the at least one conductive portion is provided and in at least a partial peripheral area of ​​the at least one conductive portion, and the limiting portion protrudes from the driving electrode and has a first height in a direction perpendicular to the driving substrate.

[0008] In some embodiments, a difference between a second height of the at least one conductive portion in a direction perpendicular to the driving substrate and the first height is in a range from about 0 micrometers to about 1.5 micrometers.

[0009] In some embodiments, the restriction is made of a conductive material.

[0010] In some embodiments, the at least one conductive portion is spaced apart from the limiting portion.

[0011] In some embodiments, the connection structure further includes a conductive connection portion located on the driving electrode and between the at least one conductive portion and the restriction portion.

[0012] In some embodiments, each of the at least one conductive portion includes a main body portion located on the driving electrode and a conductive layer covering the entire surface of the main body portion; and the conductive connecting portion, the limiting portion and the conductive layer are made of the same conductive material.

[0013] In some embodiments, each of the at least one conductive portion includes a main body portion located on the driving electrode and a conductive layer covering all other surfaces of the main body portion except a portion of the surface away from the driving electrode; and the conductive connecting portion, the limiting portion and the conductive layer are made of the same conductive material.

[0014] In some embodiments, the at least one conductive portion is in direct contact with the limiting portion on the surface of the driving electrode.

[0015] In some embodiments, each of the at least one conductive portion includes a main body portion located on the driving electrode and a conductive layer covering an entire surface of the main body portion; and the restriction portion and the conductive layer are made of the same conductive material.

[0016] In some embodiments, each of the at least one conductive portion includes a main body portion located on the driving electrode and a conductive layer covering all other surfaces of the main body portion except a portion of the surface away from the driving electrode; and the limiting portion and the conductive layer are made of the same conductive material.

[0017] In some embodiments, the material of the main body is copper, aluminum or nickel, and the material of the conductive layer is molybdenum or copper.

[0018] In some embodiments, a height of the conductive layer in a direction perpendicular to the driving substrate is approximately equal to a height of the limiting portion in a direction perpendicular to the driving substrate.

[0019] In some embodiments, the limiting portion surrounds the at least one conductive portion, and its orthographic projection on the driving substrate is a hollow closed figure, and the thickness of the limiting portion in a direction parallel to the plane of the driving substrate is in a range of about 0.2 microns to about 0.3 microns.

[0020] In some embodiments, the at least one conductive portion is in a pyramidal shape, and the at least one conductive portion is in a cone shape.

[0021] In some embodiments, a plurality of driving transistors are disposed in the driving substrate; each of the plurality of driving transistors includes a source, a drain, a gate and an active layer, and each driving transistor controls the driving electrode by connecting its drain with the corresponding driving electrode.

[0022] On the other hand, a display device is provided, comprising the display back panel described above and a plurality of micro light emitting diodes, wherein each of the plurality of micro light emitting diodes comprises a first pole and a second pole, and the first pole and the second pole are respectively connected to two adjacent connection structures on the display back panel.

[0023] In some embodiments, the limiting portions of the two adjacent connecting structures are at least on opposite sides of the two adjacent connecting structures.

[0024] In some embodiments, the plurality of micro-LEDs are arranged into an array structure of multiple rows and columns; the display back panel includes multiple rows and columns of connection structures arranged corresponding to the plurality of micro-LEDs; the limiting portions of two adjacent connection structures on the same column are at least arranged on opposite sides of the two adjacent connection structures; and the limiting portions of two adjacent connection structures on the same row are at least arranged on opposite sides of the two adjacent connection structures.

[0025] On the other hand, a method for manufacturing a display backplane is provided, comprising: forming a plurality of driving electrodes on a driving substrate; forming a connecting structure on each of the plurality of driving electrodes so that the orthographic projection of the connecting structure on the driving substrate is located within the orthographic projection of the corresponding driving electrode on the driving substrate, wherein forming the connecting structure on each of the plurality of driving electrodes comprises: forming at least one conductive portion on the driving electrode so that an area of ​​a first cross-section of the at least one conductive portion is negatively correlated with a distance between the first cross-section and a surface of the driving substrate, and the first cross-section is parallel to the surface of the driving substrate; and forming a limiting portion on a side of the driving electrode where the at least one conductive portion is provided and at least in a partial peripheral area of ​​the at least one conductive portion, wherein the limiting portion protrudes from the driving electrode and has a first height in a direction perpendicular to the driving substrate.

[0026] In some embodiments, forming at least one conductive portion on the driving electrode comprises: forming a first photoresist pattern on a driving substrate on which the driving electrode is formed, so as to form a first through hole exposing the driving electrode at a position on the driving electrode where the at least one conductive portion is to be formed; forming a metal column in the first through hole; forming a second photoresist pattern on the metal column with a diameter smaller than that of the metal column; and etching the metal column using the second photoresist pattern as a mask to form the at least one conductive portion, and forming a limiting portion on a side of the driving electrode on which the at least one conductive portion is provided and at least in a partial peripheral area of ​​the at least one conductive portion comprises: removing the first photoresist pattern and the second photoresist pattern; forming a limiting structure on the driving electrode at least in a partial peripheral area of ​​the at least one conductive portion; A metal material is deposited on the exposed side walls of the limiting structure to form a limiting portion at least in a partial peripheral area of ​​the at least one conductive portion, wherein forming the limiting structure on the driving electrode at least in a partial peripheral area of ​​the at least one conductive portion includes: sequentially forming a planarization layer and a first metal layer on the driving substrate from which the first photoresist pattern and the second photoresist pattern are removed, and making the height of the planarization layer in a direction perpendicular to the driving substrate greater than the height of the at least one conductive portion; forming a third photoresist pattern on the first metal layer, and etching the first metal layer to form a first metal pattern; using the first metal pattern as a mask, etching the planarization layer to form a surface exposing the at least one conductive portion away from the driving electrode and a side wall on which the limiting portion will be formed, so as to form the limiting structure.

[0027] In some embodiments, depositing a metal material on the exposed sidewalls of the limiting structure to form a limiting portion at least in a partial peripheral area of ​​the at least one conductive portion includes: removing the third photoresist pattern, and forming a second metal layer on the sidewalls of the planarization layer and the surface of the at least one conductive portion away from the drive electrode and the exposed drive electrode; coating the entire surface of the drive substrate formed with the second metal layer with a fourth photoresist; plasma-treating the fourth photoresist in an oxygen atmosphere to thin the fourth photoresist to reach a selected thickness, and exposing the entire top surface portion of the second metal layer and a portion of the side surface close to the top surface thereof, and keeping the fourth photoresist covering the at least one conductive portion or keeping the top of the at least one conductive portion exposed from the fourth photoresist; etching away the second metal layer and the first metal layer pattern not covered by the fourth photoresist, and keeping the at least one conductive portion unetched, and the second metal layer on the sidewall of the planarization layer covered by the fourth photoresist forms the limiting portion. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] The accompanying drawings are used to provide a further understanding of the present disclosure and constitute a part of the specification. Together with the following specific embodiments, they are used to explain the present disclosure but do not constitute a limitation of the present disclosure. In the accompanying drawings:

[0029] Figures 1a-1f is a schematic structural diagram of a display backplane according to an embodiment of the present disclosure;

[0030] Figure 2a-2h is a schematic diagram of a connection structure according to an embodiment of the present disclosure;

[0031] Figure 3a-3d is a schematic diagram of a connection structure according to an embodiment of the present disclosure;

[0032] Figure 4 is a schematic diagram of binding an LED chip to a connection structure according to an embodiment of the present disclosure;

[0033] Figure 5 A flow chart of a method for manufacturing a display backplane according to an embodiment of the present disclosure;

[0034] Figure 6 A process flow chart for manufacturing a display backplane according to an embodiment of the present disclosure;

[0035] Figure 7a-7m' It is a schematic structural diagram of a display backplane corresponding to each step in the method for manufacturing a display backplane according to an embodiment of the present disclosure;

[0036] Figures 8a-8f Schematic diagram of the structure of a display device according to an embodiment of the present disclosure. DETAILED DESCRIPTION

[0037] The specific implementation of the present disclosure is described in detail below in conjunction with the accompanying drawings. It should be understood that the specific implementation described herein is only used to illustrate and explain the present disclosure, and is not used to limit the present disclosure.

[0038] In a Micro-LED display device, the size of each Micro-LED is usually less than or equal to 100 micrometers (μm). The distance between two adjacent Micro-LEDs in an array arrangement is also in the micrometer range. Therefore, how to improve the binding efficiency and reliability of the Micro-LEDs and the corresponding driving electrodes in the display backplane during the process of transferring each Micro-LED to the display substrate becomes a very important issue.

[0039] To this end, according to one aspect of the present disclosure, a display backplane is provided. Figures 1a-1f As shown, the display backplane includes: a driving substrate 10; a plurality of driving electrodes 11, which are arranged on the driving substrate 10; a plurality of connection structures, which are respectively arranged on the plurality of driving electrodes 11, and the orthographic projection of each of the plurality of connection structures on the driving substrate 10 is located within the orthographic projection of the corresponding driving electrode 11 on the driving substrate 10. The connection structure includes: at least one conductive portion 12, which is arranged on the driving electrode 11, and the area of ​​the first cross section of the at least one conductive portion 12 is negatively correlated with the distance between the first cross section and the surface of the driving substrate 10, and the first cross section is parallel to the surface of the driving substrate; and a limiting portion 13, which is located on one side of the driving electrode 11 where the at least one conductive portion 12 is arranged and at least located in at least a part of the peripheral area of ​​the at least one conductive portion 12, and the limiting portion 13 protrudes from the driving electrode 11 and has a first height in a direction perpendicular to the driving substrate 10. In some embodiments, the angle between the limiting portion 13 and the plane where the driving substrate 10 is located ranges from 85° to 95°, in which case, the limiting portion 13 can also be considered to be almost perpendicular to the driving substrate 10.

[0040] The display backplane disclosed in the present invention includes a plurality of connection structures, each of which is used to connect to the electrode pins of the electronic device for controlling the electronic device. The connection structure in the display backplane disclosed in the present invention includes a conductive portion for electrical connection, which is made of a conductive material and is used to electrically connect to the electrode pins of the electronic device; and a limiting portion arranged at the periphery of the conductive portion to limit the binding material for electrically connecting the conductive portion to the pins of the electronic device. With this arrangement, when the conductive portion on the display backplane is electrically connected to the electrode pins of the electronic device (such as Micro-LED), the binding material will be blocked by the limiting portion and confined to a predetermined area without overflowing, thereby avoiding short circuit problems, such as Figure 4 shown.

[0041] The at least one conductive portion 12 on the driving electrode 11 may include one or more conductive portions. Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e , Figure 2f They are perspective views of a limiting portion 13 surrounding a conductive portion 12, Figure 2a' , Figure 2b' , Figure 2c' , Figure 2d' , Figure 2e' , Figure 2f' They are Figure 2a , Figure 2b , Figure 2c , Figure 2d , Figure 2e , Figure 2f A top view of Figure 1a , Figure 1b , Figure 1c , Figure 1d , Figure 1e , Figure 1f They are Figure 2a' , Figure 2b' , Figure 2c' , Figure 2d' , Figure 2e' , Figure 2f' Cross-sectional views along corresponding lines A-A', B-B', CC', D-D', E-E', FF'. Figure 3a , Figure 3b , Figure 3c , Figure 3d They are perspective views of one limiting portion 13 surrounding three conductive portions 12 . Of course, the number of conductive portions 12 surrounded by one limiting portion 13 can be set as needed.

[0042] The orthographic projection of each of the multiple connecting structures on the driving substrate 10 is located within the orthographic projection of the corresponding driving electrode 11 on the driving substrate 10, which means that the orthographic projection of each connecting structure on the driving substrate 10 substantially all falls within the orthographic projection of the corresponding driving electrode 11 on the driving substrate 10, or the orthographic projection of each connecting structure on the driving substrate 10 at least partially falls within the orthographic projection of the corresponding driving electrode 11 on the driving substrate 10, and there is partial overlap.

[0043] The limiting portion 13 is located in at least a portion of the peripheral area of ​​at least one conductive portion 12, which means that the limiting portion 13 is provided at least in a portion of the peripheral area of ​​the conductive portion 12. Figure 2gAs shown, in two adjacent connection structures corresponding to two electrodes (P and N) of an LED chip 15, the limiting parts 13 of the two connection structures are only arranged on opposite sides of the two adjacent connection structures to prevent the binding material from overflowing and contacting when binding the two electrodes and causing a short circuit. For example, when the driving electrode 11 arranged on the driving electrode is rectangular and the conductive part 12 is conical, the limiting part 13 can be a columnar protrusion arranged only on one edge side of the rectangle. Figure 2g The limiting parts 13 of two adjacent connection structures are columnar protrusions respectively arranged on the adjacent edges of two adjacent driving electrodes, which are similar to two retaining walls, limiting the binding materials corresponding to the two electrodes on their respective driving electrodes during binding, and will not overflow to the adjacent driving electrodes, thereby effectively avoiding short circuits caused by undesired contact of the binding materials. Figure 2g As shown, the limiting portion 13 should have a certain size in a direction perpendicular to the arrangement direction of two adjacent driving electrodes, and the size is usually greater than or equal to the size of the conductive portion in this direction to effectively play a role of binding and isolation.

[0044] Alternatively, if Figure 2h As shown in FIG. 1 , for driving electrodes arranged in multiple rows, the connection structure provided thereon also needs to take into account the binding isolation between the electrodes of two LED chips adjacent to each other in the column direction. Figure 2h As shown, the limiting portions of the connection structures are arranged not only on opposite sides of the connection structures adjacent to each other in the row direction, but also on opposite sides of the connection structures adjacent to each other in the column direction, as shown in FIG. Figure 2h As shown. Figure 2h In the embodiment, the limiting portion 13 includes three parts arranged on three edges of a rectangular driving electrode, and presents a semi-enclosed structure to the conductive part inside the driving electrode. The three parts can be as follows: Figure 2h As shown, the first part is connected; optionally, the three parts may not contact each other, but be isolated. As described above, the limiting part 13 is a protrusion protruding from the surface of the driving electrode and having a first height, and a gap is formed between it and the conductive part arranged inside, which can be used to accommodate the binding material during binding, so as to limit the binding material for each electrode to the gap formed by its corresponding connection structure, thereby preventing the binding material from overflowing to the adjacent connection structure in the row direction or column direction to cause an undesirable short circuit.

[0045] Of course, you can also Figure 2a' , Figure 2b' , Figure 2c' , Figure 2d' , Figure 2e' , Figure 2f' As shown, the limiting portion 13 is arranged around the entire periphery of the at least one conductive portion 12, so that the binding isolation effect is the best. Figure 2h and Figure 2g The structure shown occupies less area of ​​the drive electrode surface.

[0046] The driving substrate 10 is provided with a driving transistor, which is connected to the driving electrode 11 and is used to provide an electrical signal to the driving electrode. Figure 1a-1f As shown, the driving substrate 10 includes a substrate 111, a buffer layer 112 on the substrate 111, an active layer 113 on the buffer layer 112, a gate insulating layer 114 on the active layer 113 and the buffer layer 112, a gate 115 on the gate insulating layer 114 corresponding to the active layer 113, a dielectric layer 116 on the gate 115 and the gate insulating layer 114, a source 1171 and a drain 1172 on the dielectric layer 116 connected to the active layer 113 through via holes in the gate insulating layer 114 and the dielectric layer 116, the source 1171 and the drain 1172 and a planarization layer 118 on the dielectric layer 116, and a passivation layer 119 on the planarization layer 118. The driving electrode 11 is connected to the drain 1172 through via holes in the planarization layer 118 and the passivation layer 119. In this embodiment, the driving transistor is a top-gate transistor. The present application is not limited to this, and a bottom-gate transistor may also be used. Of course, the driving electrodes 11 may also be disposed on other types of substrates as required.

[0047] like Figure 4As shown, when the LED chip 15 is bound by the binding material 14 using the connection structure of the present invention, the LED chip 15 can be bound to the driving substrate 10 using the combined structure of the conductive part 12 and the limiting part 13 of the present invention. First, align the top of the conductive part 12 with the binding material 14 at the electrode (P and N) position of the LED chip 15 in the vertical direction, wherein the binding material 14 is usually made of soft metals such as indium or tin, and the binding material 14 is usually prepared on the LED chip 15 by thermal evaporation. Then, the top of the conductive part 12 is inserted into the binding material 14 at the electrode (P and N) position of the LED chip 15. After the binding material 14 is inserted into the top of the conductive part 12, it overflows and spreads around the top of the conductive part 12. The spreading binding material 14 is blocked by the limiting part 13 and enters the space formed by the conductive part 12 and the limiting part 13. Then, under the condition of a temperature lower than the melting point of the metal of the binding material 14, a low-temperature treatment is performed in a vacuum environment at a temperature of about 200°C (for example, low-temperature treatment for 50 minutes), so that the metal in the binding material 14 and the metal of the conductive part 12 and the limiting part 13 diffuse with each other. Due to the existence of the limiting part 13, the binding materials 14 corresponding to the N electrode and the P electrode positions of the LED chip 15 can be prevented from contacting each other when side overflow occurs, thereby preventing the N electrode and the P electrode of the LED chip 15 from short-circuiting. In this way, even if the spacing between the pins of the two electrodes of each LED chip 15 or the electrodes of adjacent LED chips 15 is very small, the limiting part included in the conductive part of the connection structure in the embodiment of the present application can also limit the binding material 14, and no overflow will occur, thereby solving the problem of binding short circuit caused by small spacing. Therefore, the connection structure disclosed in the present invention is particularly suitable for micro light emitting diodes.

[0048] In some embodiments, the difference between the second height of the conductive portion 12 in a direction perpendicular to the drive substrate 10 and the first height of the limiting portion 13 in a direction perpendicular to the drive substrate 10 is in a range of about 0 micrometers to about 1.5 micrometers. Figure 1b , Figure 1c , Figure 1e As shown, the second height of the conductive portion 12 is equal to the first height of the limiting portion 13. Figure 1a , Figure 1d , Figure 1f As shown, the second height of the conductive portion 12 is greater than the first height of the limiting portion 13. In some examples, the height of the conductive portion 12 may be in the range of 2.8 to 3.5 microns, and the height of the limiting portion 13 may be in the range of 2.0 to 2.5 microns. In a specific example, the height of the conductive portion 12 may be 3.0 microns, and the height of the limiting portion 13 may be 2.2 microns.

[0049] In some embodiments, the limiting portion 13 can be made of a conductive material like the conductive portion 12, so that the surface of the conductive portion 12 and the surface of the limiting portion 13 can both be in electrical contact with the binding material 14, thereby increasing the electrical contact area, reducing the resistance, and reducing the power consumption. However, the present application is not limited to this. The main purpose of introducing the limiting portion 13 in the present application is to limit the short circuit between the binding materials corresponding to the adjacent connection structures. Therefore, all structures that limit the overflow of the internal binding materials belong to the scope of the present application. For example, the limiting portion 13 is not limited to being made of a conductive material, and it can also be made of an insulating material. In this case, the limiting portion 13 is only used to avoid the short circuit between the binding materials corresponding to the adjacent connection structures, and it cannot affect the electrical connection between the driving electrode 11 and the (P and N) electrodes of the LED chip 15.

[0050] In some embodiments, the conductive portion 12 and the limiting portion 13 are spaced apart. Figure 1a-1d As shown, the conductive portion 12 and the restricting portion 13 are not in contact with each other on the surface of the driving electrode 11 .

[0051] In some embodiments, the connection structure further includes a conductive connection portion 16 disposed on the driving electrode 11 and between the conductive portion 12 and the limiting portion 13. Figure 1b As shown, the conductive portion 12 and the limiting portion 13 are connected on the surface of the driving electrode 11 through the conductive connecting portion 16. In this case, the limiting portion 13, the conductive connecting portion 16 and the conductive portion 12 can be made of the same conductive material. Optionally, the limiting portion 13, the conductive connecting portion 16 and the conductive portion 12 can be integrally formed using the same conductive material to simplify the preparation process.

[0052] In some embodiments, the conductive portion 12 includes a main body portion 120 disposed on the driving electrode 11 and a conductive layer 17 covering the entire surface of the main body portion. Figure 1c As shown. The conductive connection part 16, the limiting part 13 and the conductive layer 17 can be made of the same conductive material. In this case, the main body 120 can be made of a non-conductive material, and the conductive connection part 16, the limiting part 13 and the conductive layer 17 can be made simultaneously by the same process.

[0053] In some embodiments, the conductive portion 12 includes a main body portion 120 disposed on the driving electrode 11 and a conductive layer 17 covering all other surfaces of the main body portion 120 except a portion of the surface away from the driving electrode 11 (for example, the surface of the tip of the main body portion 120). Figure 1dAs shown, in this case, the main body 120 can be made of a conductive material to increase the electrical contact area with the binding material and reduce the contact resistance. The conductive connecting portion 16, the limiting portion 13 and the conductive layer 17 can be made of the same conductive material. Optionally, the limiting portion 13, the conductive connecting portion 16 and the conductive layer 17 can be integrally formed using the same conductive material to simplify the preparation process. For example, the height of the conductive layer 17 in a direction perpendicular to the drive substrate can be approximately equal to the first height.

[0054] In some embodiments, the conductive portion 12 and the limiting portion 13 may be in direct contact on the surface of the driving electrode 11. In some embodiments, the conductive portion 12 may include a main body portion 120 disposed on the driving electrode 11 and a conductive layer 17 covering the entire surface of the main body portion. Figure 1e Optionally, the conductive portion 12 includes a main body portion 120 disposed on the driving electrode 11 and a conductive layer 17 covering a surface of the main body portion 120 except for a portion of the surface away from the driving electrode 11 (for example, a surface of the tip of the main body portion 120), as shown in FIG. Figure 1f The restriction portion 13 and the conductive layer 17 may be made of the same conductive material. Figure 1e The height of the conductive layer 17 in the direction perpendicular to the drive substrate 10 is equal to the first height, that is, the overall height of the conductive portion 12 is the height of the conductive layer 17 in the direction perpendicular to the drive substrate 10 . Figure 1f The height of the conductive layer 17 in the direction perpendicular to the drive substrate 10 is approximately equal to the first height, that is, the overall height of the conductive portion 12 is greater than the first height.

[0055] In some embodiments, the material of the main body 120 is copper, aluminum or nickel, and the material of the conductive layer 17 is molybdenum or copper. Of course, other materials can also be selected to prepare the corresponding main body and conductive layer as needed. For example, as described above, when a conductive layer is provided on the entire surface of the conductive part 12, the main body inside the conductive layer can be prepared by a non-conductive material.

[0056] The present application does not limit the materials of the main body, the conductive layer and the limiting part, as long as the prepared connection structure can meet the required strength and conductivity.

[0057] In some embodiments, when the limiting portion 13 surrounds at least one conductive portion 12, the orthographic projection of the limiting portion 13 on the driving substrate may be a closed figure. In a specific example, the closed figure is a hollow circle or rectangle, such as a tubular structure, such as a round tube or a square tube, such as Figure 2a'-Figure 2f' In addition, the thickness d of the limiting portion 13 in the direction parallel to the plane where the driving substrate 10 is located is in the range of about 0.2 micrometers to about 0.3 micrometers, as shown in FIG. Figure 2a' shown.

[0058] In some embodiments, the conductive portion 12 is in a cone shape. Figure 2a-Figure 3d As shown, the horizontal cross section of the conductive part 12 is circular, that is, the conductive part 12 is in the shape of a cone. However, the present disclosure is not limited thereto, and the conductive part 12 can also be other types of cones, such as a rectangular or triangular cross section in the horizontal direction.

[0059] According to one aspect of the present disclosure, a method for manufacturing the above-mentioned display backplane is provided. Figure 5 As shown, the method includes the following steps S110, S120 and S130.

[0060] In step S110 , a plurality of driving electrodes 11 are formed on the driving substrate 10 .

[0061] For example, Figure 7a As shown, an electrode layer is formed on the driving substrate 10 by sputtering deposition, and then patterned to form a plurality of driving electrodes 11 .

[0062] FIG7 only schematically shows the drive substrate 10. Figure 1a As shown, a driving transistor and an electrode line are formed on the driving substrate 10 , and the drain of the driving transistor and the electrode line are respectively connected to the driving electrode formed on the surface of the driving substrate 10 through the conductive material in the via hole.

[0063] In step S120, at least one conductive portion 12 is formed on the driving electrode 11. The area of ​​the first cross section of the at least one conductive portion 12 is negatively correlated with the distance between the first cross section and the surface of the driving substrate 10, and the first cross section is parallel to the surface of the driving substrate 10.

[0064] In step S130, a limiting portion 13 is formed on one side of the driving electrode 11 where at least one conductive portion 12 is provided, at least around a portion of the at least one conductive portion 12. The limiting portion 13 protrudes from the driving electrode 11 and has a first height in a direction perpendicular to the driving substrate 10.

[0065] The conductive portion 12 and the limiting portion 13 formed as above are provided as connection structures on the corresponding driving electrodes, and their overall orthographic projections on the driving substrate are located within the orthographic projections of the driving electrodes on the driving substrate.

[0066] Figure 6 is a process flow chart for manufacturing a display backplane according to an embodiment of the present disclosure, Figure 7a-Figure 7m' Schematic diagram of the structure of the display backplane corresponding to each step in the process flow of manufacturing the display backplane according to the embodiment of the present disclosure. Figure 6 , Figure 7a-7m' Come to Figure 5 The method for manufacturing the display backplane shown is described in detail.

[0067] In one embodiment, the method for manufacturing a display backplane of the present application includes steps S201 to S214.

[0068] In step S201, at least one driving electrode 11 is formed on the driving substrate 10. Figure 7a shown.

[0069] In step S202, a first photoresist pattern 101 is formed on the driving substrate 10 on which at least one driving electrode 11 is formed, so as to form a first through hole 121 exposing the driving electrode 11 at a position on the driving electrode 11 where at least one conductive portion 12 is to be formed. Specifically, first, a photoresist is applied on the entire driving substrate 10 on which at least one driving electrode 11 is formed. The thickness of the applied photoresist can be determined by the height of the conductive portion 12 to be formed. For example, if the height of the conductive portion 12 to be formed is 3.0 μm, the thickness of the applied photoresist can be 3.0 μm. Then, the photoresist is exposed and developed to form the first photoresist pattern 101, so as to form a first through hole 121 exposing the driving electrode 11 at a position on the driving electrode 11 where at least one conductive portion 12 is to be formed. Figure 7b shown.

[0070] In step S203, a metal column 102 is formed in the first through hole 121. Specifically, Figure 7c As shown, the metal pillar 102 can be formed above the exposed driving electrode 11 (i.e., in the first through hole 121) by electroplating. For example, Cu ions can be deposited by electroplating to form a copper pillar, but the present disclosure is not limited thereto, and other processes can also be used to form metal pillars of other materials (such as aluminum, nickel, etc.).

[0071] In step S204, a second photoresist pattern 103 having a diameter smaller than that of the metal pillar 102 is formed on the metal pillar 102. Figure 7d As shown, photoresist is coated on the metal pillar 102, and the size of the coated photoresist is smaller than the size of the metal pillar 102, that is, the photoresist coated on the metal pillar 102 completely falls into the top surface area of ​​the metal pillar 102, and the center of the photoresist coated on the metal pillar 102 can be on the same vertical line as the center of the top surface of the metal pillar. For example, if the coated photoresist and the metal pillar 102 are both similar polygons, the length of the diagonal line of the coated photoresist is smaller than the length of the diagonal line of the metal pillar 102; if the coated photoresist and the metal pillar 102 are both circular, the diameter of the coated photoresist is smaller than the diameter of the metal pillar 102.

[0072] In step S205, the metal pillar 102 is etched using the second photoresist pattern 103 as a mask to form at least one conductive portion 12. Specifically, the second photoresist pattern 103 is used as a spike mask to etch the metal pillar 102 using a wet etching process to obtain the conductive portion 12. Figure 7e shown.

[0073] In step S206, the first photoresist pattern 101 and the second photoresist pattern 103 are removed to obtain the conductive portion 12. Figure 7f shown.

[0074] In step S207, a planarization layer 104 and a first metal layer 105 are sequentially formed on the drive substrate 10 from which the first photoresist pattern 101 and the second photoresist pattern 103 are removed, and the height of the planarization layer 104 in a direction perpendicular to the drive substrate 10 is at least greater than the height of the conductive portion 12. Specifically, firstly, a resin is applied to form the planarization layer 104, and the thickness of the planarization layer 104 after curing is ensured to be greater than the height of the conductive portion 12. Then, a metal (e.g., molybdenum) is deposited on the planarization layer 104 to form the first metal layer 105, such as Figure 7g shown.

[0075] In step S208, a third photoresist pattern 106 is formed on the first metal layer 105, and the first metal layer 105 is etched to form a first metal pattern 105'. Specifically, first, a photoresist is applied on the first metal layer 105, and the photoresist is patterned to form a third photoresist pattern 106. Then, the first metal layer 105 is etched using the third photoresist pattern 106 as a mask, thereby obtaining a first metal pattern 105'. Figure 7g shown.

[0076] In step S209, the planarization layer 104 is etched using the first metal pattern 105' as a mask to expose the entire surface of the conductive portion 12 away from the drive substrate 10 and the sidewall on which the restriction portion is to be formed. Specifically, the first metal pattern 105' can be used as a hard mask to etch the planarization layer 104 to form a planarization layer pattern 104', thereby exposing almost the entire surface of the conductive portion 12 away from the drive substrate 10, such as Figure 7h The planarization layer 104 and the first metal layer 105 form a limiting structure at the etched portion, and the limiting structure is used to form a subsequent limiting portion.

[0077] In step S210, the third photoresist pattern 106 is removed, and a second metal layer 107 is formed on the entire drive substrate 10. Specifically, a sputtering process can be used to deposit metal (eg, molybdenum Mo) to form the second metal layer 107 covering the entire surface of the drive substrate 10. Figure 7i As shown. The second metal layer 107 can be used to form the limiting portion 13 later, so its thickness is required to be able to keep the shape fixed when the side wall support on the back is removed. For example, when molybdenum is used to form the second metal layer 107, its thickness on the side wall (i.e., in the direction parallel to the plane where the drive substrate 10 is located) is required to be in the range of 0.2 to 0.3 μm.

[0078] In step S211, a fourth photoresist 108 is coated on the entire surface of the driving substrate 10 on which the second metal layer 107 is formed. Figure 7j shown.

[0079] In step S212 , the fourth photoresist 108 is plasma treated in an oxygen atmosphere to be thinned to a selected thickness to expose a portion of the second metal layer 107 . The height of the thinned fourth photoresist 108 ′ is lower than that of the first metal layer pattern 105 ′.

[0080] Specifically, the fourth photoresist 108 is directly subjected to plasma treatment in an oxygen atmosphere to reduce the thickness of the fourth photoresist 108. By controlling the time and ion concentration of the plasma treatment in the oxygen atmosphere, a fourth photoresist 108' of a selected thickness can be obtained. For example, after the fourth photoresist 108 is thinned, the top surface of the second metal layer 107 and part of the side surface close to the top surface can be exposed, and it is also necessary to ensure that the height of the fourth photoresist 108' remaining at the exposed position of the conductive portion 12 is greater than the height of the conductive portion 12, that is, the remaining fourth photoresist 108' covers the conductive portion 12, such as Figure 7k Optionally, in one embodiment, after the thickness of the fourth photoresist 108 becomes thinner, it is also necessary to ensure that the height of the conductive portion 12 is greater than the thickness of the fourth photoresist 108' remaining at the exposed position of the conductive portion 12, that is, the top of the conductive portion 12 is exposed from the fourth photoresist 108', as shown in FIG. Figure 7k' Shown

[0081] In step S213, the second metal layer 107 not covered by the fourth photoresist 108' and the first metal layer pattern 105' below the second metal layer 107 are etched away, and the second metal layer 107 at the sidewall covered by the fourth photoresist 108' forms the limiting portion 13. Specifically, the second metal layer 107 and the first metal layer pattern 105' not covered by the fourth photoresist 108' can be removed by a wet etching process, such as Figure 7l and Figure 7l' As shown, since the fourth photoresist 108' covers the second metal layer 107 at the sidewall, the thickness of the fourth photoresist 108' limits the height of the formed limiting portion 13, that is, the fourth photoresist 108' achieves self-alignment of the height of each limiting portion 13.

[0082] In step S214, the planarization layer 104 and the fourth photoresist 108 are removed to form a final connection structure. Figure 7m and 7m’ As shown, the height of the limiting portion 13 of the connection structure can be in the range of 2.0 to 2.5 μm, and the thickness d can be in the range of 0.2 to 0.3 μm; the height of the conductive portion 12 can be in the range of 2.5 μm to 3.5 μm. For example, the height of the conductive portion 12 can be 3.0 μm, and the height of the limiting portion 13 can be 2.2 μm. Figure 7m' As shown, the top of the conductive part 12 is exposed from the conductive layer 17, so that the conductive part 12 is in direct contact with the subsequent, for example, LED chip 5. In this way, when the conductive part 12 is made of copper or aluminum, etc., and the conductive layer 17 is made of molybdenum, etc., since the resistivity of copper or aluminum is less than the resistivity of molybdenum, the contact resistance between the LED chip 5 and the connecting structure can be reduced.

[0083] In the connection structure of the display backplane formed by the above process, the second metal layer 107 formed between the limiting portion 13 and the conductive portion 12 can be used as a part of the conductive layer 17 or the conductive connecting portion 16 to connect the limiting portion 13 and the conductive portion 12 together. Figure 1b , Figure 1c Optionally, the second metal layer 107 may be deposited only on the sidewalls to form a structure in which the limiting portion 13 and the conductive portion 12 are not connected together. Figure 1a The connection structure shown.

[0084] The present invention is not limited to the above-mentioned preparation method. For example, a non-conductive material may be used to form the limiting portion 13. In this case, the limiting portion only serves to limit the binding material.

[0085] According to one aspect of the present disclosure, a display device is provided, which includes the above-mentioned display backplane and a plurality of micro light emitting diodes. Figure 8a As shown, each micro-LED includes a first electrode pin N led from the N region and a second electrode pin P led from the P region, that is, a first electrode and a second electrode. The first electrode and the second electrode are respectively connected to two connection structures on the display backplane through a binding material 14, as shown in FIG. Figures 8a-8f shown. Figure 8a-8f The display backplanes in Figure 1a-1f Display backplane in.

[0086] A plurality of pairs of driving electrodes are usually arranged on the display backplane, and each pair of driving electrodes is arranged corresponding to two electrode pins N and P of a micro light-emitting diode to ensure that each driving electrode can be electrically connected to the corresponding electrode pin through a corresponding connection structure. For example, the orthographic projection of the first electrode pin N and the second electrode pin P on the driving substrate is located at the orthographic projection of the corresponding driving electrode on the driving substrate.

[0087] In this embodiment, the first electrode pin N of the micro-LED is electrically connected to the drain 1172 of the transistor provided in the driving backplane through the binding material 14, and the second electrode pin P is electrically connected to the electrode line 1173 provided in the driving backplane through the binding material 14, so as to control the micro-LED through the driving substrate. The electrode line 1173 can be formed by the same material and the same patterning process as the source 1171 and the drain 1172 of the driving transistor.

[0088] like Figure 8a As shown, the conductive part 12 in each connection structure that plays an electrical contact role is set as a conical structure with a sharp end, so that when binding, the conductive part can effectively penetrate into the binding material coated on the corresponding electrode pin to ensure good electrical contact between the two. After electrical contact occurs, the binding material will expand to the periphery.

[0089] In some embodiments, the limiting portions 13 of two adjacent connection structures are at least on opposite sides of the two adjacent connection structures, that is, the orthographic projection of the limiting portion 13 on the drive substrate is a non-closed figure. For example, the limiting portion 13 may also be arranged only on one side of the conductive portion 12, that is, the limiting portion 13 may also be arranged only at a position where an undesirable short circuit of the binding material may occur, such as Figure 2g In two adjacent connection structures, limiting parts are provided only on opposite sides of the two adjacent connection structures (such as opposite sides a and a') to prevent the binding material between the two adjacent connection structures from short-circuiting.

[0090] In some embodiments, a plurality of micro-LEDs are arranged in an array structure of multiple rows and columns, and the limiting portions of the connection structures corresponding to two adjacent micro-LEDs on the same column are located in the peripheral region of the corresponding at least one conductive portion at least on adjacent opposite sides; and the limiting portions of the connection structures corresponding to two adjacent micro-LEDs on the same row are located in the peripheral region of the corresponding at least one conductive portion at least on adjacent opposite sides. Figure 2h As shown, when the display backplane includes an array-arranged connection structure, limiting portions are provided only on opposite sides of two adjacent connection structures in the same column or row (e.g., opposite sides b and b', and c and c') to avoid short circuits in the binding materials between adjacent connection structures.

[0091] In this application, since the display device has Figure 1a-1fThe connection structure shown in the display backplane in FIG. 1 includes a conductive portion 12 and a limiting portion 13 disposed on the periphery of the conductive portion 12, thereby defining a gap area between the conductive portion 12 and the limiting portion 13. When the micro-LED 15 is bounded to the display backplane by the binding material 14, the binding material 14 will be confined inside by the limiting portion 13, thereby preventing the binding material 14 from overflowing, thereby solving the binding short circuit problem caused by the small spacing between the electrodes, and increasing the contact area between the binding electrodes, reducing the resistance, and reducing the power consumption.

[0092] It is to be understood that the above embodiments are merely exemplary embodiments used to illustrate the principles of the present disclosure, but the present disclosure is not limited thereto. For those of ordinary skill in the art, various modifications and improvements can be made without departing from the spirit and substance of the present disclosure, and these modifications and improvements are also considered to be within the scope of protection of the present disclosure.

Claims

1. A display backplane, comprising: Driver substrate; A plurality of driving electrodes, which are located on the driving substrate; The plurality of driving electrodes are coupled to a plurality of electrode pins of the electronic device; The number of the plurality of driving electrodes is the same as the number of the plurality of electrode pins; A plurality of connection structures, which are respectively located on the plurality of driving electrodes; Wherein, the connection structure comprises: at least one conductive portion, which is located on the driving electrode, and an area of ​​a first cross section of the at least one conductive portion is negatively correlated with a distance between the first cross section and a surface of the driving substrate, and the first cross section is parallel to the surface of the driving substrate; and A limiting portion is located on one side of the driving electrode where the at least one conductive portion is provided and in at least a partial peripheral area of ​​the at least one conductive portion, the limiting portion protruding from the driving electrode and having a first height in a direction perpendicular to the driving substrate.

2. The display backplane according to claim 1, wherein: The at least one conductive portion includes a plurality of conductive portions; and the plurality of conductive portions are arranged in an array, and / or the plurality of conductive portions have the same shape.

3. The display backplane according to claim 1, wherein: A plurality of driving transistors are arranged in the driving substrate; Each of the plurality of driving transistors includes a source electrode, a drain electrode, a gate electrode, and an active layer; And, at least one driving electrode among the plurality of driving electrodes is connected to a drain of at least one driving transistor among the plurality of driving transistors.

4. The display backplane according to claim 1, wherein: A difference between a second height of the at least one conductive portion in a direction perpendicular to the driving substrate and the first height is in a range from about 0 micrometers to about 1.5 micrometers.

5. The display backplane according to claim 1, wherein: The limiting portion is made of a conductive material.

6. The display backplane according to claim 1, wherein: The at least one conductive portion is spaced apart from the limiting portion.

7. The display back panel according to claim 6, wherein: The connection structure further includes a conductive connection portion located on the driving electrode and between the at least one conductive portion and the restriction portion.

8. The display back panel according to claim 7, wherein: Each of the at least one conductive portion includes a main body portion located on the driving electrode and a conductive layer covering the entire surface of the main body portion or all other surfaces except a portion of the surface away from the driving electrode; and The conductive connecting portion, the limiting portion and the conductive layer are made of the same conductive material.

9. The display back panel according to claim 1, wherein: The at least one conductive portion is in direct contact with the restriction portion on the surface of the driving electrode.

10. The display back panel according to claim 9, wherein: Each of the at least one conductive portion includes a main body portion located on the driving electrode and a conductive layer covering the entire surface of the main body portion or all other surfaces except a portion of the surface away from the driving electrode; and The restriction portion and the conductive layer are made of the same conductive material.

11. The display back panel according to claim 8, wherein: A height of the conductive layer in a direction perpendicular to the drive substrate is approximately equal to a height of the restricting portion in a direction perpendicular to the drive substrate.

12. The display back panel according to claim 8, wherein: The material of the main body is copper, aluminum or nickel, and the material of the conductive layer is molybdenum or copper.

13. The display back panel according to claim 1, wherein: The limiting portion surrounds the at least one conductive portion, and its orthographic projection on the driving substrate is a hollow closed figure.

14. The display back panel according to claim 13, wherein: The closed figure is circular or rectangular, and the thickness of the limiting portion along a direction parallel to a plane where the driving substrate is located is in a range of about 0.2 micrometers to about 0.3 micrometers.

15. The display back panel according to claim 1, wherein: The at least one conductive portion has a cone shape.

16. The display back panel according to claim 15, wherein: The at least one conductive portion has a cone shape.

17. A display device comprising the display backplane according to any one of claims 1 to 16 and a plurality of micro light emitting diodes, wherein: Each of the micro light emitting diodes is correspondingly connected to a plurality of the connection structures.

18. The display device according to claim 17, wherein: Each of the plurality of micro-LEDs includes a first pole and a second pole, and the plurality of connection structures connected to the micro-LEDs include two connection structures, and the two connection structures are respectively connected to the first pole and the second pole of the micro-LEDs.

19. The display device according to claim 18, wherein: Among the two connection structures connected to the micro-light-emitting diode, the limiting part of the connection structure connected to the first pole is arranged closer to the second pole relative to the conductive part of the connection structure; the limiting part of the connection structure connected to the second pole is arranged closer to the first pole relative to the conductive part of the connection structure.

20. The display device according to claim 19, wherein: The two connection structures connected to the micro light emitting diode are arranged in an axisymmetric manner.

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