Backplane, backlight module, display device

Abstract

The embodiment of the present application provides a backplane, a backlight module, and a display device, which belongs to the technical field of display backplanes, and includes a substrate; a first metal electrode line, which is arranged on the substrate; a micro-light emitting diode, which is arranged on the first metal electrode line; the micro-light emitting diode includes a first semiconductor layer, a light emitting layer, and a second semiconductor layer which are stacked, and the second semiconductor layer is electrically connected to the first metal electrode line; a first flat layer, which covers the first metal electrode line; a second metal electrode line, which is arranged on the first flat layer; and a second flat layer, which covers the second metal electrode line located on the first platform insulating layer. The backplane, backlight module, and display device provided by the embodiment of the present application can reduce the process flow of the backplane and improve the display brightness of the backplane.

Description

Technical Field

[0001] The embodiments of the present application relate to the technical field of display backplanes, and more specifically, to a backplane, a backlight module, and a display device. Background Art

[0002] Micro-LED (micro light-emitting diode) display technology refers to a display technology that uses self-luminous micron-sized LEDs as light-emitting pixel units and assembles them on a drive panel to form a high-density LED array. Due to the small size, high integration and self-luminescence of micro LED chips, compared with LCD and OLED, it has greater advantages in brightness, resolution, contrast, energy consumption, service life, response speed and thermal stability.

[0003] At present, in the manufacturing process of Micro-LED display backplane, an insulating layer and an ITO film need to be plated after the Micro-LED is transferred, and holes need to be made in the insulating layer on the top, which makes the manufacturing process of the Micro-LED display backplane more complicated. In addition, the ITO film is a semi-transparent film, which will also have a certain impact on the display brightness of the display backplane. Summary of the invention

[0004] The embodiments of the present application provide a backplane, a backlight module, and a display device, which are intended to reduce the process flow of the backplane and improve the display brightness of the backplane.

[0005] A first aspect of an embodiment of the present application provides a backplane, including:

[0006] substrate;

[0007] A first metal electrode line is disposed on the substrate;

[0008] A micro light emitting diode, wherein the micro light emitting diode is arranged on the first metal electrode line; the micro light emitting diode comprises a first semiconductor layer, a light emitting layer, and a second semiconductor layer which are stacked, wherein a projection area of ​​the first semiconductor layer on the substrate is smaller than a projection area of ​​the light emitting layer on the substrate, a projection area of ​​the first semiconductor layer on the substrate is smaller than a projection area of ​​the second semiconductor layer on the substrate, and the second semiconductor layer is electrically connected to the first metal electrode;

[0009] a first flat layer, the first flat layer covers the first metal electrode line, the first flat layer covers the light-emitting layer and the second semiconductor layer of the micro-LED, and the first flat layer at least partially overlaps with the first semiconductor layer;

[0010] A second metal electrode line is disposed on the first planar layer; and the second metal electrode line at least partially overlaps with the first semiconductor layer;

[0011] A second planar layer covers the second metal electrode line on the first platform insulating layer.

[0012] Optionally, a bonding metal layer is provided on the first metal electrode line, and the micro light emitting diode is bonded to the bonding metal layer.

[0013] Optionally, a thickness of the first planar layer from a surface facing away from the substrate to the substrate is greater than a thickness of the light-emitting layer from a surface facing away from the substrate to the substrate.

[0014] Optionally, in a direction perpendicular to the substrate, heights of the second metal electrode lines and the second planar layer on the sidewalls of the first semiconductor layer are lower than heights of the sidewalls of the first semiconductor layer.

[0015] Optionally, a protective film layer is provided, wherein the protective film layer covers the second flat layer.

[0016] Optionally, a thickness of the protective film layer from a side away from the substrate to the substrate is smaller than a thickness of the first semiconductor layer from a side away from the substrate to the substrate.

[0017] Optionally, an ohmic contact layer is provided between the second metal electrode line and the first semiconductor layer.

[0018] Optionally, the first semiconductor layer is N-GAN.

[0019] Optionally, the thickness of the first semiconductor layer is greater than the thickness of the second semiconductor layer.

[0020] Optionally, the orthographic projection of the first semiconductor layer on the substrate is located within the orthographic projection of the second semiconductor layer on the substrate.

[0021] Optionally, the micro-LED includes a first surface, a second surface and a side surface, the first surface is a side of the micro-LED away from the substrate, the second surface is a side of the micro-LED close to the substrate, the first surface and the second surface are parallel to each other, the first surface and the second surface are connected through the side surface, and the angle between the side surface and the second surface is 45°-70°.

[0022] Optionally, a plurality of the first metal electrode lines and a plurality of the second metal electrode lines are provided, and the plurality of the first metal electrode lines are provided in parallel on the substrate; a plurality of the second metal electrode lines are provided in parallel on the first flat layer, and the first metal electrode lines and the second metal electrode lines are perpendicular to each other.

[0023] A second aspect of the embodiments of the present application provides a backlight module, comprising a display panel and a backplane provided in the first aspect of the embodiments of the present application.

[0024] A third aspect of the embodiments of the present application provides a display device, comprising a driving circuit and a backlight module as provided in the third aspect of the embodiments of the present application.

[0025] Beneficial effects:

[0026] The present application provides a backplane, a backlight module, and a display device. A first metal electrode line, a micro-light emitting diode, a first flat layer, a second metal electrode line, and a second flat layer are arranged on a substrate. Since the second metal electrode line surrounds the side wall of the first semiconductor layer covering the micro-light emitting diode, an electrical connection between the second metal electrode line and the micro-light emitting diode is achieved. There is no need to arrange an ITO film to connect the second metal electrode line and the micro-light emitting diode, thereby simplifying the manufacturing process of the backplane. At the same time, since there is no ITO film layer to block it, the display brightness of the backplane is improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for use in the description of the embodiments of the present application will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present application. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0028] Figure 1 is a schematic diagram of a cross-sectional structure of a backplane proposed in one embodiment of the present application;

[0029] Figure 2 It is a schematic cross-sectional structure diagram of an embodiment of the present application;

[0030] Figure 3 It is a schematic diagram of a planar structure of a backplane proposed in one embodiment of the present application;

[0031] Figure 4 It is a flowchart of the steps of a method for preparing a backplane proposed in one embodiment of the present application;

[0032] Figure 5 is a schematic cross-sectional structure diagram of a backplane after substrate manufacturing is completed according to an embodiment of the present application;

[0033] Figure 6 is a schematic cross-sectional structure diagram of a backplane after the first metal electrode line is manufactured according to an embodiment of the present application;

[0034] Figure 7 is a schematic cross-sectional structure diagram of a backplane after the bonding metal layer is manufactured according to an embodiment of the present application;

[0035] Figure 8 It is a schematic cross-sectional structure diagram of a backplane for transferring micro-LEDs proposed in one embodiment of the present application;

[0036] Fig. 9 It is a schematic cross-sectional structure diagram of a backplane for completing the transfer of micro-LEDs proposed in one embodiment of the present application;

[0037] Fig.10 is a schematic cross-sectional structure diagram of a backplane after the first flat layer is manufactured according to an embodiment of the present application;

[0038] Fig.11 is a schematic cross-sectional structure diagram of a backplane after etching of the first flat layer according to an embodiment of the present application;

[0039] Fig.12 is a schematic cross-sectional structure diagram of a backplane after the second metal electrode line is manufactured according to an embodiment of the present application;

[0040] Fig.13 is a schematic cross-sectional structure diagram of a backplane after the second flat layer is manufactured according to an embodiment of the present application;

[0041] Fig.14 is a schematic cross-sectional structure diagram of a backplane after etching of the second flat layer according to an embodiment of the present application;

[0042] Fig.15 It is a schematic diagram of the cross-sectional structure of a backplane after etching of the second metal electrode line proposed in one embodiment of the present application.

[0043] Explanation of the accompanying drawings: 10, substrate; 11, first metal electrode line; 12, bonding metal layer; 13, micro light-emitting diode; 131, first semiconductor layer; 132, light-emitting layer; 133, second semiconductor layer; 134, matching metal layer; 14, first flat layer; 15, second metal electrode line; 16, second flat layer. DETAILED DESCRIPTION

[0044] The following will be combined with the drawings in the embodiments of the present application to clearly and completely describe the technical solutions in the embodiments of the present application. Obviously, the described embodiments are part of the embodiments of the present application, not all of the embodiments. Based on the embodiments in the present application, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of this application.

[0045] In the related art, when manufacturing the Micro-LED backplane, it is necessary to form a first metal electrode line on the substrate, transfer the Micro-LED to the first metal electrode line, and then form an insulating layer and a second metal electrode line. However, since there is no conduction between the second metal electrode line and the Micro-LED, it is also necessary to plate an ITO film, and make holes in the insulating layer at the top of the Micro-LED and the second metal electrode line, and use ITO to achieve conduction between the second metal line and the Micro-LED. However, such a manufacturing process is relatively complicated, resulting in an increase in the manufacturing cost of the Micro-LED backplane. At the same time, the ITO film is a semi-transparent film, which will absorb the brightness of the Micro-LED to a certain extent, resulting in a decrease in the display brightness of the Micro-LED backplane. The presence of the ITO film will also affect the resolution of the entire display backplane.

[0046] In view of this, the present application provides a backplane, a backlight module, and a display device. By arranging a first metal electrode line, a micro-light-emitting diode, a first flat layer, a second metal electrode line, and a second flat layer on a substrate, since the second metal electrode line surrounds the side wall of the first semiconductor layer covering the micro-light-emitting diode, an electrical connection between the second metal electrode line and the micro-light-emitting diode is achieved, and there is no need to arrange an ITO film to connect the second metal electrode line and the micro-light-emitting diode, thereby simplifying the manufacturing process of the backplane. At the same time, since there is no ITO film layer to block it, the display brightness of the backplane is improved.

[0047] Embodiment 1

[0048] Reference Figure 1 As shown, a backplane disclosed in an embodiment of the present application includes, from bottom to top of the backplane, a substrate 10, a first metal electrode line 11, a micro-light-emitting diode 13, a first flat layer 14, a second metal electrode line 15 and a second flat layer 16.

[0049] Specifically, the substrate 10 may be a glass substrate, a PCT substrate or an FPC substrate.

[0050] Reference Figure 3 As shown, the first metal electrode line 11 is arranged on the substrate 10, and a plurality of the first metal electrode lines 11 are arranged, and the plurality of first metal electrode lines 11 are parallel to each other. At the same time, a bonding metal layer 12 is formed on the first metal electrode line 11, and the material of the bonding metal layer 12 can be tin. When the micro-LED 13 is transferred, the micro-LED 13 is bonded to the bonding metal layer 12, so that the micro-LED 13 can be better fixedly connected to the first metal electrode line 11, thereby improving the yield of the backplane.

[0051] Reference Figure 2As shown, the micro-LED 13 is arranged on the first metal electrode line 11, and the micro-LED 13 includes a first semiconductor layer 131, a light-emitting layer 132, and a second semiconductor layer 133 that are stacked. Specifically, the projection area of ​​the first semiconductor layer 131 on the substrate 10 is smaller than the projection area of ​​the light-emitting layer 132 on the substrate 10, and the projection area of ​​the first semiconductor layer 131 on the substrate 10 is smaller than the projection area of ​​the second semiconductor layer 133 on the substrate 10, that is, the orthographic projection of the first semiconductor layer 131 on the substrate 10 is located within the orthographic projection of the second semiconductor layer 133 on the substrate 10, so that the normal light emission of the micro-LED 13 and the conduction efficiency of the micro-LED 13 can be ensured.

[0052] In this embodiment, the material of the first semiconductor layer 131 is N-GaN, and the material of the second semiconductor layer 133 is P-GaN. In this way, when manufacturing the micro-LED 13, the thickness of the first semiconductor layer 131 can be greater than the thickness of the second semiconductor layer 133, thereby increasing the overlap effect between the first semiconductor layer 131 and the second metal electrode line 15, which is more conducive to the conduction of the first semiconductor layer 131. The light-emitting layer 132 is a multi-layer quantum well light-emitting structure, and the first semiconductor layer 131 and the second semiconductor layer 133 realize the connection between the micro-LED 13 and the circuit, so that the light-emitting layer 132 emits light.

[0053] The second semiconductor layer 133 is electrically connected to the first metal electrode line 11 , and a matching metal layer 134 is provided on the surface of the second semiconductor layer 133 close to the first metal electrode line 11 . The material of the matching metal layer may be tin, so that the micro-LED 13 can be bonded to the bonding metal layer 12 .

[0054] In practical applications, the shape of the micro-LED 13 can be stepped or truncated. The micro-LED 13 includes a first surface, a second surface, and a side surface. The first surface is the side of the micro-LED away from the substrate, and the second surface is the side of the micro-LED close to the substrate. The first surface and the second surface are parallel to each other, and the first surface and the second surface are connected through the side surface. The angle between the side surface and the second surface is set to 45°-70° to ensure that the second metal electrode line 15 will not be broken when the second metal electrode line 15 is formed.

[0055] In this embodiment, the micro LED 13 is in a truncated cone shape, and the angle between the side surface of the micro LED 13 and the second surface is 60°.

[0056] Reference Figure 1 As shown, the first planar layer 14 covers the first metal electrode line 11 , and the first planar layer 14 covers the light emitting layer 132 and the second semiconductor layer 133 of the micro LED 13 , and the first planar layer 14 at least partially overlaps the first semiconductor layer 131 .

[0057] Specifically, the thickness of the first flat layer 14 from the surface away from the substrate 10 to the substrate 10 is greater than the thickness of the light-emitting layer 132 from the surface away from the substrate 10 to the substrate 10, so that the first flat layer 14 can cover the light-emitting layer 132, so that the first flat layer forms protection for the light-emitting layer 132, and the micro-LED 13 can emit light normally, while insulating the first metal electrode line 11 and the second metal electrode line 15. The material of the first flat layer 14 is selected to be an insulating material that can block light, such as black photoresist, resin or UV glue, so that the crosstalk between the Micro-LEDs is reduced when emitting light.

[0058] Reference Figure 1 and Figure 3 As shown, the second metal electrode line 15 is arranged on the first flat layer 14, and a plurality of second metal electrode lines 15 are also arranged, and the plurality of second metal electrode lines 15 are parallel to each other, and the second metal electrode line 15 is perpendicular to the first metal electrode line 11. The second metal electrode line 15 overlaps at least partially with the first semiconductor layer 131 of the micro-LED 13, so that the second metal electrode line 15 and the micro-LED 13 are electrically connected, and there is no need to set an ITO film, thereby simplifying the manufacturing process of the backplane and saving process costs. In addition, without the obstruction of the ITO film, the display brightness and resolution of the backplane can also be effectively improved. In addition, since the second metal electrode line 15 is opaque, it can also prevent the micro-LED 13 from leaking light from the side wall, further reducing the mutual crosstalk when the micro-LED 13 emits light.

[0059] It should be noted that when the micro-LED 13 is mounted upright, the first semiconductor layer 131 of the micro-LED 13 is N-GaN. At this time, since the thickness of the N-GAN layer is thicker, the film forming range of the second metal electrode line 15 surrounding and wrapped in the N-GAN layer is wider, and it is easier to form the film; when the micro-LED 13 is inverted, the first semiconductor layer 131 is a P-GAN layer, and the second metal electrode line 15 can also be electrically connected to the P-GAN layer.

[0060] The second planarizing layer 16 covers the second metal electrode line 15 and serves as an etching barrier and prevents the second metal electrode line 15 from being oxidized. The second planarizing layer 16 can be made of an organic insulating material, such as a resin or UV glue; or an inorganic insulating film, such as a SiO2 film or a SiNx film.

[0061] Specifically, the side walls of the first semiconductor layer 131 are sequentially covered with the second metal electrode lines 15 and the second flat layer 16 from the inside to the outside, and in the direction perpendicular to the substrate 10, the heights of the second metal electrode lines 15 and the second flat layer 16 on the side walls of the first semiconductor layer 131 are lower than the height of the first semiconductor layer 131, that is, the side of the micro-LED 13 away from the substrate 10 is exposed, so that the micro-LED 13 emits light therefrom.

[0062] After adopting the above-mentioned backplane structure, since the second metal electrode line 15 surrounds the side wall of the first semiconductor layer 131 covering the micro-light-emitting diode 13, the electrical connection between the second metal electrode line 15 and the micro-light-emitting diode 13 is achieved, and there is no need to set an ITO film to connect the second metal electrode line 15 and the micro-light-emitting diode 13, thereby simplifying the manufacturing process of the backplane. At the same time, since there is no ITO film layer to block it, the display brightness of the backplane is improved.

[0063] In one embodiment, in order to further protect the backplane, a protective film layer may be formed on the second flat layer 16. The material of the protective film layer may be an organic insulating material, such as a resin or UV glue; or an inorganic insulating film, such as a SiO2 film layer or a SiNx film layer. In addition, the thickness of the protective film layer from the side away from the substrate 10 to the substrate 10 is less than the thickness of the first semiconductor layer 131 from the side away from the substrate 10 to the substrate 10, so that the protective film layer will not block the light emitted by the micro-LED 13.

[0064] In one embodiment, in order to reduce the contact resistance between the second metal electrode line 15 and the first semiconductor layer 131, an ohmic contact layer can be set between the second metal electrode line 15 and the first semiconductor layer 131, so as to improve the display brightness of the back panel and reduce power consumption. The material of the ohmic contact layer can be Ni / Au, etc.

[0065] Embodiment 2

[0066] Figure 4 A flow chart showing the steps of a method for preparing a backplane is shown. Figure 4 As shown, an embodiment of the present application provides a method for preparing a backplane, the method comprising:

[0067] Step 201: Provide a substrate 10.

[0068] Specifically, the substrate 10 may be a glass substrate, such as Figure 5 shown.

[0069] Step 202 : forming a first metal electrode line 11 on the substrate 10 .

[0070] Specifically, a first metal electrode line 11 is formed on the back substrate by a film-forming yellow photolithography process, and a plurality of first metal electrode lines 11 are arranged on the first metal electrode line 11, and the plurality of first metal electrode lines 11 are parallel to each other; then a bonding metal layer 12 is formed on the first metal electrode line 11 by a film-forming lift-off process, such as Figure 6 and Figure 7 shown.

[0071] Step 203: Transfer the micro-LED 13 to the first metal electrode line 11, the micro-LED 13 includes a first semiconductor layer 131, a light-emitting layer 132 and a second semiconductor layer 133 which are stacked, the projection area of ​​the first semiconductor layer 131 on the substrate 10 is smaller than the projection area of ​​the light-emitting layer 132 on the substrate 10, the projection area of ​​the first semiconductor layer 131 on the substrate 10 is smaller than the projection area of ​​the second semiconductor layer 133 on the substrate 10, and the second semiconductor layer 133 is electrically connected to the first metal electrode line 11.

[0072] Specifically, a bonding metal layer 12 is formed on the first metal electrode line 11, and the micro light emitting diode 13 is transferred to the bonding metal layer 12 through a transfer process, so that the micro light emitting diode 13 is bonded to the bonding metal layer 12, thereby realizing electrical connection between the micro light emitting diode 13 and the first metal electrode line 11. Figure 8 and Fig. 9 shown.

[0073] Step 204 : forming a first planar layer 14 on the first metal electrode line 11 , the first planar layer 14 covers the light emitting layer 132 and the second semiconductor layer 133 of the micro LED 13 , and the first planar layer 14 at least partially overlaps the first semiconductor layer 131 .

[0074] Specifically, a first flat layer 14 is formed on the first metal electrode line 11 by a Slit or spin coating process. The material of the first flat layer 14 may be an insulating material such as a black photoresist, a resin or a UV glue. Then, the first flat layer 14 is etched by an ICP or Plasma etching process to expose the first semiconductor layer 131 of the micro-LED 13. The etching of the first flat layer 14 does not exceed the light-emitting layer 132, so that the first flat layer 14 surrounds the side wall of the second semiconductor layer 133 and the side wall of the light-emitting layer 132 covering the micro-LED 13, so as to protect the light-emitting layer 132. Fig.10 and Fig.11 shown.

[0075] Step 205 : forming a second metal electrode line 15 on the first planar layer 14 , wherein the second metal electrode line 15 at least partially overlaps with the first semiconductor layer 131 .

[0076] Step 206 : forming a second planarization layer 16 on the second metal electrode line 15 .

[0077] Specifically, the second metal electrode line 15 is formed in a full-surface shape by using a film forming process so that the second metal electrode line 15 completely covers the micro light-emitting diode 13. Fig.12 shown.

[0078] Then, a second flat layer 16 is formed on the second metal electrode line 15 by a Slit or spin coating process. The second flat layer 16 can be made of an organic insulating material, such as a resin or a UV glue. The second flat layer 16 can also be made of a non-polar insulating film, such as a SiO2 film layer or a SiNx film layer, and is formed on the second metal electrode line 15 by a CVD film forming process. Fig.13 shown.

[0079] The second flat layer 16 is etched to below the top surface of the micro-LED 13 and above the thickness of the second metal electrode line 15, that is, the second metal electrode line 15 on the side of the micro-LED 13 away from the substrate 10 is exposed. Fig.14 shown.

[0080] Then, the second metal electrode line 15 on the side of the micro-LED 13 away from the substrate 10 is etched by a wet etching process to expose the side of the micro-LED 13 away from the substrate 10, so as to realize normal light emission of the micro-LED 13. Fig.15 shown.

[0081] Since the second metal electrode line 15 surrounds the side wall of the first semiconductor layer 131 covering the micro-LED 13, the electrical connection between the second metal electrode line 15 and the micro-LED 13 is achieved. There is no need to set an ITO film to connect the second metal electrode line 15 and the micro-LED 13, thereby simplifying the manufacturing process of the backplane. At the same time, since there is no ITO film layer to block it, the display brightness of the backplane is improved.

[0082] Embodiment 3

[0083] The embodiment of the present application provides a backlight module, including a display panel and a backplane provided in the first embodiment of the present application.

[0084] Embodiment 4

[0085] An embodiment of the present application provides a display device, including a driving circuit and a backlight module as provided in Embodiment 3 of the present application.

[0086] Specifically, the display device can be a computer monitor, a television, a billboard, a laser printer with display function, a telephone, a mobile phone, a personal digital assistant (PDA), a laptop computer, a digital camera, a camcorder, a viewfinder, a vehicle, a large-area wall, a theater screen or a stadium sign, etc.

[0087] It should be noted that the various embodiments in this specification are described in a progressive manner, and each embodiment focuses on the differences from other embodiments. The same or similar parts between the various embodiments can be referenced to each other.

[0088] It should also be noted that, in this article, the orientation or position relationship indicated by the terms "center", "up", "down", "left", "right", "vertical", "horizontal", "inside", "outside", etc. is based on the orientation or position relationship shown in the drawings, which is only for the convenience of describing the present application and simplifying the description, and does not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present application. In addition, relational terms such as "first" and "second" are only used to distinguish one entity or operation from another entity or operation, and do not necessarily require or imply that there is any such actual relationship or order between these entities or operations, nor can they be understood as indicating or implying relative importance. Moreover, the terms "include", "comprise" or any other variant thereof are intended to cover non-exclusive inclusion, so that a process, method, article or terminal device including a series of elements includes not only those elements, but also includes other elements not explicitly listed, or also includes elements inherent to such process, method, article or terminal device. Without more restrictions, an element defined by the phrase "comprising a ..." does not exclude the existence of other identical elements in the process, method, article or terminal device comprising the element.

[0089] The technical solution provided by the present application is described in detail above. The principle and implementation method of the present application are described in this article using specific examples. The description of the above embodiments is only used to help understand the present application, and the content of this specification should not be understood as limiting the present application. At the same time, for those of ordinary skill in the art, according to the present application, there will be different forms of changes in the specific implementation methods and application scopes. It is not necessary and impossible to list all the implementation methods here, and the obvious changes or modifications derived therefrom are still within the scope of protection of the present application.

Claims

1. A backplane, characterized in that: include: substrate; A first metal electrode line is disposed on the substrate; A micro light emitting diode, wherein the micro light emitting diode is arranged on the first metal electrode line; the micro light emitting diode comprises a first semiconductor layer, a light emitting layer, and a second semiconductor layer which are stacked, wherein a projection area of ​​the first semiconductor layer on the substrate is smaller than a projection area of ​​the light emitting layer on the substrate, a projection area of ​​the first semiconductor layer on the substrate is smaller than a projection area of ​​the second semiconductor layer on the substrate, and the second semiconductor layer is electrically connected to the first metal electrode; a first flat layer, the first flat layer covers the first metal electrode line, the first flat layer covers the light-emitting layer and the second semiconductor layer of the micro-LED, and the first flat layer at least partially overlaps with the first semiconductor layer; a second metal electrode line, disposed on the first planar layer; the second metal electrode line at least partially overlaps the first semiconductor layer, and a height from a side of the second metal electrode line away from the substrate to the substrate is less than a height from a side of the first semiconductor layer away from the substrate to the substrate; a second planar layer, wherein the second planar layer covers the second metal electrode line located on the first planar layer; A protective film layer is covered on the second flat layer, and a thickness from a side of the protective film layer away from the substrate to the substrate is smaller than a thickness from a side of the first semiconductor layer away from the substrate to the substrate.

2. The back plate according to claim 1, characterized in that: A bonding metal layer is provided on the first metal electrode line, and the micro light emitting diode is bonded to the bonding metal layer.

3. The back plate according to claim 1, characterized in that: The thickness of the first planar layer from a surface facing away from the substrate to the substrate is greater than the thickness of the light emitting layer from a surface facing away from the substrate to the substrate.

4. The back plate according to claim 3, characterized in that: In a direction perpendicular to the substrate, heights of the second metal electrode line and the second planar layer on the sidewall of the first semiconductor layer are lower than that of the first semiconductor layer.

5. The back plate according to claim 1, characterized in that: An ohmic contact layer is disposed between the second metal electrode line and the first semiconductor layer.

6. The back plate according to claim 4, characterized in that: The first semiconductor layer is N-GaN.

7. The back plate according to claim 6, characterized in that: The thickness of the first semiconductor layer is greater than the thickness of the second semiconductor layer.

8. The back plate according to claim 4, characterized in that: An orthographic projection of the first semiconductor layer on the substrate is located within an orthographic projection of the second semiconductor layer on the substrate.

9. The back plate according to claim 8, characterized in that: The micro-LED includes a first surface, a second surface and a side surface, the first surface is a side of the micro-LED away from the substrate, the second surface is a side of the micro-LED close to the substrate, the first surface and the second surface are parallel to each other, the first surface and the second surface are connected through the side surface, and the angle between the side surface and the second surface is 45°-70°.

10. The backplane according to any one of claims 1 to 9, characterized in that: There are multiple first metal electrode lines and multiple second metal electrode lines, and the multiple first metal electrode lines are arranged in parallel on the substrate; multiple second metal electrode lines are arranged in parallel on the first flat layer, and the first metal electrode lines are perpendicular to the second metal electrode lines.

11. A backlight module, characterized in that: The device comprises a display panel and the back plate as claimed in claim 10.

12. A display device, characterized in that: The device comprises a driving circuit and the backplane as claimed in claim 10.

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