Display module and preparation method therefor, and electronic device

Abstract

The present application relates to the technical field of display. Provided are a display module and a preparation method therefor, and an electronic device, which are used for improving the problems of the image quality of a display module being low, etc. The display module comprises a driving substrate, a conductive grid, a transparent conductive layer and a plurality of micro light-emitting diodes, wherein the driving substrate comprises a plurality of first electrode contacts and second electrode contacts, each micro light-emitting diode comprises a first electrode and a second electrode, the plurality of micro light-emitting diodes are in one-to-one correspondence with the plurality of first electrode contacts, and the first electrodes of the micro light-emitting diodes are electrically connected to the corresponding first electrode contacts; the conductive grid is electrically connected to the second electrode contacts; and the transparent conductive layer covers the plurality of micro light-emitting diodes and the conductive grid, and the second electrodes of the micro light-emitting diodes are electrically connected to the conductive grid by means of the transparent conductive layer, the resistivity of the material of the conductive grid being lower than the resistivity of the material of the transparent conductive layer.

Description

Display module, manufacturing method thereof, and electronic device

[0001] This application claims priority to the Chinese patent application filed with the State Intellectual Property Office on November 27, 2023, with application number 202311604262.4 and application name “Display module, preparation method thereof, and electronic device”, the entire contents of which are incorporated by reference into this application. Technical Field

[0002] The present application relates to the field of display technology, and in particular to a display module, a preparation method thereof, and an electronic device. Background Art

[0003] With the development of micromachining technology, light-emitting diode (LED) optical chips have gradually penetrated from the lighting field into the display field. Micro LED display technology is a self-luminous display technology. Micro LEDs, also known as micron-level LEDs, are achieved by integrating arrayed micron-level LED units (also known as LED units) on a driver substrate with active drive functions. The lower electrode of the micro LED is electrically connected to the driver substrate, and the upper electrode is electrically connected to the common electrode and the driver backplane using a transparent conductive material. The transparent conductive material used for the upper electrode has a low conductivity, resulting in a severe voltage drop (IR droop) in high-resolution display screens, affecting the display quality.

[0004] Summary of the Invention

[0005] The present application provides a display module and a preparation method thereof, and an electronic device for improving problems such as low imaging quality of the display module.

[0006] In a first aspect, an embodiment of the present application provides a display module, which includes a driving substrate, a plurality of micro-light-emitting diodes, a conductive grid and a transparent conductive layer, wherein the driving substrate includes a plurality of first electrode contacts and a second electrode contact, and the first electrode contacts and the second electrode contacts are used to form a driving circuit with the micro-light-emitting diodes; a plurality of micro-light-emitting diodes, the micro-light-emitting diodes include a first electrode and a second electrode, the plurality of micro-light-emitting diodes correspond one-to-one to the plurality of electrode contacts, and the first electrodes of the micro-light-emitting diodes are electrically connected to the electrode contacts; a conductive grid, the conductive grid includes a plurality of grids, the micro-light-emitting diodes correspond to the grids, and the conductive grid is electrically connected to the second electrode contacts; a transparent conductive layer covers the plurality of micro-light-emitting diodes and the conductive grid, the second electrodes of the micro-light-emitting diodes are electrically connected to the conductive grid through the transparent conductive layer, and the resistivity of the material of the conductive grid is less than the resistivity of the material of the transparent conductive layer.

[0007] The display module provided in the embodiment of the present application is provided with a conductive grid, which is electrically connected to the transparent conductive layer and the common electrode. The conductive grid is made of a material with good conductivity and has a lower resistance than the transparent conductive layer. The current of the micro-light-emitting diode can reach the nearest conductive grid through the transparent conductive layer and then flow to the common electrode through the conductive grid to form a loop, without having to completely pass through the transparent conductive layer to flow to the common electrode. This can avoid the voltage drop problem caused by the large resistance of the transparent conductive layer and improve the imaging quality.

[0008] In one possible implementation, a common electrode is further provided on the driving substrate, and the common electrode is in contact with the second electrode contact and the conductive grid, and the conductive grid is electrically connected to the second electrode contact through the common electrode. In this way, the first electrode of the micro light-emitting diode is electrically connected to the first electrode contact on the driving substrate, and the second electrode of the micro light-emitting diode can be connected to the second electrode contact in sequence through the transparent conductive layer, the conductive grid, and the common electrode.

[0009] In one possible implementation, the conductive grid is electrically connected to the second electrode contact through the internal circuit of the driving substrate, so that the first electrode of the micro light-emitting diode is electrically connected to the first electrode contact on the driving substrate, and the second electrode of the micro light-emitting diode can be connected to the second electrode contact in sequence through the transparent conductive layer, the conductive grid and the internal circuit of the driving substrate.

[0010] In one possible implementation, a height control layer is further provided on the driver substrate, and the upper surface of the micro-LED is flush with the upper surface of the height control layer. In the embodiment of the present application, the height control layer is provided so that the upper surface of the micro-LED is flush with the upper surface of the height control layer. The height control layer is used to precisely control the height of the micro-LED, thereby improving the display effect.

[0011] In one possible implementation, the display module further includes a dielectric filling layer disposed between adjacent micro-LEDs and between the height control layer and the driver substrate. The material of the height control layer, the dielectric filling layer, and the micro-LEDs have different removal rates. By utilizing the different removal rates of the height control layer, the dielectric filling layer, and the micro-LEDs, the wafer can be planarized to a height that remains at the top surface of the height control layer, ensuring that the top surface of the micro-LEDs is flush with the top surface of the height control layer. The height of the micro-LEDs can be defined by the top surface of the height control layer and the surface of the driver substrate.

[0012] In one possible implementation, multiple micro-light emitting diodes are arranged in the area defined by each grid. For example, the display module can be a color display module, and each pixel includes micro-light emitting diodes of multiple different colors. The multiple micro-light emitting diodes included in the pixel can be arranged in the area defined by the same grid. The conductive grid can block the light of the micro-light emitting diodes to avoid crosstalk between the light of the micro-light emitting diodes of different pixels.

[0013] In one possible implementation, a micro-light emitting diode is arranged in the area defined by each grid. For example, the display module can be a monochrome display module, and each pixel includes a monochrome micro-light emitting diode. The micro-light emitting diode is arranged in the grid, and the conductive grid can block the light of the micro-light emitting diode to avoid crosstalk between the light of different micro-light emitting diodes.

[0014] In a possible implementation, the width of the grid lines of the conductive grid is 10 nm-1000 nm.

[0015] In one possible implementation, the conductive grid includes a lower surface facing the driving substrate and an upper surface facing away from the driving substrate in a direction perpendicular to the driving substrate, and the micro light-emitting diode includes a lower surface facing the driving substrate and an upper surface facing away from the driving substrate in a direction perpendicular to the driving substrate; the distance from the lower surface of the conductive grid to the driving substrate is less than or equal to the distance from the lower surface of the micro light-emitting diode to the driving substrate; and the distance from the upper surface of the conductive grid to the driving substrate is greater than or equal to the distance from the upper surface of the micro light-emitting diode to the driving substrate.

[0016] In one possible implementation, the height of the conductive grid in a direction perpendicular to the driving substrate is 1 to 2 times the height of the micro-LED, which can block the light of the micro-LED and avoid crosstalk between different micro-LEDs.

[0017] In one possible implementation, the display module also includes a lens layer, which is arranged on the transparent conductive layer. The lens layer may include multiple lenses, and the multiple lenses correspond one-to-one to multiple micro-light-emitting diodes. The lenses are used to collimate the light emitted by the micro-light-emitting diodes to improve the brightness and imaging quality of the display module.

[0018] In a second aspect, an embodiment of the present application also provides a method for preparing a display module, the method comprising: forming a plurality of micro-light-emitting diodes on a driving substrate, the micro-light-emitting diodes comprising a first electrode and a second electrode arranged opposite to each other, the driving substrate comprising a plurality of first electrode contacts and a second electrode contact, the plurality of micro-light-emitting diodes corresponding one-to-one to the plurality of first electrode contacts, the first electrodes of the micro-light-emitting diodes contacting the first electrode contacts corresponding to the micro-light-emitting diodes; forming a common electrode and a conductive grid on the driving substrate, the common electrode being electrically connected to the second electrode contact, the conductive grid being electrically connected to the common electrode, the conductive grid comprising a plurality of grids, the micro-light-emitting diodes corresponding to the grids, the micro-light-emitting diodes being located within an area defined by their corresponding grids; forming a transparent conductive layer, the transparent conductive layer covering the plurality of micro-light-emitting diodes and the conductive grid, the second electrodes of the micro-light-emitting diodes being electrically connected to the conductive grid through the transparent conductive layer.

[0019] In a possible implementation, before forming the common electrode and the conductive grid on the driving substrate, the method further includes: forming a height control layer on the driving substrate, wherein the upper surface of the micro light emitting diode is flush with the upper surface of the height control layer.

[0020] In one possible implementation, a height control layer is formed on a driving substrate, and the upper surface of the micro-light-emitting diode is flush with the upper surface of the height control layer, including: forming a first dielectric filling layer on the surface of a wafer after the micro-light-emitting diode is formed; forming a height control layer on the first dielectric filling layer; forming a second dielectric filling layer on the height control layer; and flattening the wafer after the second dielectric filling layer is formed so that the height of the wafer surface stops at the surface of the height control layer, and the upper surface of the micro-light-emitting diode is flush with the upper surface of the height control layer, wherein the material of the height control layer has different removal rates from the material of the micro-light-emitting diode and the materials of the first dielectric filling layer and the second dielectric filling layer.

[0021] In one possible implementation, a common electrode and a conductive grid are formed on the driver substrate, with the conductive grid contacting the common electrode. This includes forming a grid-like groove and a common electrode groove on the wafer surface after the height control layer is formed, with the grid-like groove and the common electrode groove communicating with each other; forming a conductive grid in the grid-like groove and forming a common electrode in the common electrode groove. This electrically connects the conductive grid and the common electrode, allowing the current of the micro-LED to be transmitted through the transparent conductive layer to the conductive grid, and then through the conductive grid to the common electrode, thereby reducing the resistance of the micro-LED's current loop and preventing voltage drop due to excessive resistance that could affect display quality.

[0022] In a third aspect, an electronic device is also provided, comprising a housing and a display module provided in any implementation manner of the first aspect, wherein the display module is mounted on the housing. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] FIG1 is a schematic diagram of an electronic device provided in an embodiment of the present application;

[0024] FIG2 is a schematic diagram of a display module provided in an embodiment of the present application;

[0025] FIG3 is a cross-sectional view of a display module provided in an embodiment of the present application;

[0026] FIG4 is a schematic diagram of another display module provided in an embodiment of the present application;

[0027] FIG5 is a cross-sectional view of another display module provided in an embodiment of the present application;

[0028] FIG6 is a schematic diagram of the working principle of a display module provided in an embodiment of the present application;

[0029] FIG7 is a schematic diagram of the working principle of another display module provided in an embodiment of the present application;

[0030] FIG8 is a cross-sectional view of another display module provided in an embodiment of the present application;

[0031] FIG9 is a schematic diagram of light crosstalk provided by an embodiment of the present application;

[0032] FIG10 is a schematic diagram showing the principle of preventing light crosstalk provided by an embodiment of the present application;

[0033] FIG11 is a schematic diagram of the mesh shape of a conductive mesh provided in an embodiment of the present application;

[0034] FIG12 is a schematic diagram of the shape of a metal grid provided in an embodiment of the present application;

[0035] FIG13 is a schematic diagram of another display module provided in an embodiment of the present application;

[0036] FIG14 is a cross-sectional view of another display module provided in an embodiment of the present application;

[0037] FIG15 is a cross-sectional view of another display module provided in an embodiment of the present application;

[0038] FIG16 is a schematic flow chart of a method for preparing a display module according to an embodiment of the present application;

[0039] FIG17 is a schematic flow chart of another method for preparing a display module provided in an embodiment of the present application;

[0040] FIG18 is a schematic flow chart of another method for preparing a display module according to an embodiment of the present application;

[0041] 19 to 21 are process flow charts of a method for manufacturing a display module according to an embodiment of the present application. DETAILED DESCRIPTION

[0042] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. In the present application, "at least one" refers to one or more, and "more" refers to two or more. "And / or" describes the association relationship of associated objects, indicating that there may be three relationships. For example, A and / or B can represent: the existence of A alone, the existence of A and B at the same time, and the existence of B alone, where A and B can be singular or plural. "At least one of the following items (individuals)" or similar expressions refers to any combination of these items, including any combination of single items (individuals) or plural items (individuals). For example, at least one of a, b or c can represent: a, b, c, a and b, a and c, b and c or a, b and c, where a, b and c can be single or multiple.

[0043] The embodiments of this application use terms such as "first" and "second" to distinguish objects with similar names, functions, or effects. Those skilled in the art will understand that terms such as "first" and "second" do not limit the quantity or order of execution. The term "coupled" is used to indicate an electrical connection, including direct connection via wires or connectors or indirect connection via other devices. Therefore, "coupling" should be considered a broadly defined electronic communication connection.

[0044] It should be noted that, in this application, words such as "exemplary" or "for example" are used to indicate examples, illustrations, or descriptions. Any embodiment or design described in this application as "exemplary" or "for example" should not be construed as being preferred or advantageous over other embodiments or designs. Rather, the use of words such as "exemplary" or "for example" is intended to present the relevant concepts in a concrete manner.

[0045] The solution provided in the embodiments of the present application can be applied to electronic devices, such as mobile phones, personal computers (PCs), tablet computers (pads), smart wearable products (e.g., smart watches, smart bracelets), virtual reality (VR) terminal devices, augmented reality (AR) terminal devices, vehicle-mounted terminals, displays, and other electronic devices, or any electronic device that needs to be configured with a display module. The embodiments of the present application do not impose any special restrictions on the specific forms of the above-mentioned electronic devices.

[0046] Taking the electronic device as an AR head-mounted display device as an example, the AR head-mounted display device may include AR glasses or an AR helmet, etc. For ease of explanation, refer to Figure 1, which shows a schematic diagram of AR glasses provided in an embodiment of the present application.

[0047] The AR glasses include a frame 101, temples 102, and lenses 103. The lenses 103 are mounted on the frame 101, and the temples 102 are connected to the frame 101. The temples 102 and the frame 101 allow the AR glasses to be worn in front of the user's eyes. The temples 102 are provided with a display screen that can display images or other content. The lenses 103 are optical waveguide lenses. The images or other content displayed on the display screen can be transmitted to the lenses 103 via the optical waveguide for display, and then formed in front of the user's eyes.

[0048] Due to the limited space of AR glasses, the above-mentioned display screen can be a micro light emitting diode (Micro LED) display screen. Micro LED is a micron-level display device, and its size is usually 0.1 micron to 100 microns. Miniaturization enables Micro LED to have higher luminous brightness, resolution and color saturation, faster display response speed and lower power consumption. The emergence of Micro LED display technology makes miniaturization and high resolution of devices such as AR display devices, VR display devices, near-eye display (NED) and head-up display (HUD) possible.

[0049] Please refer to Figures 2 and 3. Figure 2 shows a schematic diagram of a display module 200 provided in an embodiment of the present application, and Figure 3 shows a cross-sectional view of the display module 200 provided in an embodiment of the present application along the BB' direction in Figure 2.

[0050] The display module 200 includes a drive substrate 210, which may include a substrate 211, a drive circuit layer 212, and a protective layer 213, arranged in sequence. The drive circuit layer 212 may include multiple drive circuits or drive units for controlling the active driving of the Micro LEDs. The drive circuits typically include components such as transistors, capacitors, and resistors. A second electrode contact 215 and multiple first electrode contacts 214 are provided on the surface of the protective layer 213. The first and second electrode contacts 214, 215 are connected to the drive circuits via vias in the protective layer 213. For example, the first electrode contacts 214 may be anode contacts, and the second electrode contacts 215 may be cathode contacts.

[0051] The driving substrate 210 can be divided into a light-emitting area and a peripheral area outside the light-emitting area. The light-emitting area can be provided with a plurality of pixel units arranged in an array. Each pixel unit includes one sub-pixel or multiple sub-pixels. Each sub-pixel may include a micro light-emitting diode 220. In some possible implementations, the pixel unit may include a red sub-pixel, a green sub-pixel, and a blue sub-pixel, so that a color display can be achieved by mixing red, green, and blue. Of course, in actual applications, the luminous color of the sub-pixels in the pixel unit can be designed and determined according to the actual application environment, and is not limited here.

[0052] Referring to FIG. 3 , the micro-LED 220 includes a first semiconductor layer 221, a light-emitting layer 222, and a second semiconductor layer 223, which are sequentially stacked. The first semiconductor layer 221 is located on the side closest to the driver substrate 210, while the second semiconductor layer 223 is located on the side facing away from the driver substrate 210. The first semiconductor layer 221 can be P-type or N-type doped with a semiconductor material (e.g., gallium oxide) to provide holes or electrons. The light-emitting layer 222 can utilize a multi-quantum well layer to improve luminous efficiency. The second semiconductor layer 223 can be N-type or P-type doped with a semiconductor material (e.g., gallium nitride) to provide electrons or holes. The first and second semiconductor layers 221 and 223 are located on opposite sides of the light-emitting layer 222, and the doping types of the two semiconductor layers are opposite. If the first semiconductor layer 221 is N-type doped, the second semiconductor layer 223 is P-type doped; if the first semiconductor layer 221 is P-type doped, the second semiconductor layer 223 is N-type doped. In specific implementation, both of the above structures can be applied.

[0053] The micro-LED 220 may further include an ohmic contact layer 224 in contact with the first semiconductor layer 221. The ohmic contact layer 224 may form the first electrode of the micro-LED 220. The micro-LED 220 also includes a second electrode opposite the first electrode. In some possible implementations, a conductive contact layer may be provided on the second semiconductor layer 223 to serve as the second electrode. Alternatively, in the embodiment of the present application, a transparent conductive layer 240 in contact with the second semiconductor layer 223 may serve as the second electrode of the micro-LED 220. Multiple micro-LEDs 220 may share the same second electrode. In some possible implementations, a bonding layer 225 is further provided between the ohmic contact layer 224 and the drive substrate 210. The bonding layer 225 is used to bond the micro-LED 220 to the drive substrate 210. In this embodiment of the present application, the first semiconductor layer 221 is P-type doped and the second semiconductor layer 223 is N-type doped. In this case, the first electrode of the micro-LED 220 may be an anode, and the second electrode of the micro-LED 220 may be a cathode.

[0054] The plurality of first electrode contacts 214 are distributed in the light-emitting area, and the second electrode contacts 215 are disposed in the peripheral area. A common electrode 216 is also disposed on the drive substrate 210. The common electrode 216 is positioned corresponding to and electrically connected to the second electrode contacts 215. The plurality of first electrode contacts 214 correspond one-to-one with the plurality of micro-LEDs 220. The first electrode of each micro-LED 220 contacts the corresponding first electrode contact 214, forming an electrical connection. The plurality of micro-LEDs 220 are electrically connected to the common electrode 219 via their shared second electrode, thereby electrically connecting to the second electrode contacts 215. Thus, the micro-LEDs 220 are electrically connected to the first and second electrode contacts 214, 215, forming a drive circuit.

[0055] For example, a transparent conductive layer 240 is covered over the plurality of micro-LEDs 220 in the light-emitting area, and the second semiconductor layer 223 of the micro-LEDs 220 is electrically connected to the transparent conductive layer 240. The transparent conductive layer 240 can form a common second electrode of the plurality of micro-LEDs 220, or it can be considered that the portion of the transparent conductive layer 240 in contact with each micro-LED forms the second electrode of the micro-LED. A common electrode 216 is provided on the peripheral area of ​​the driving substrate 210. For example, the common electrode 216 can be provided on the second electrode contact 215, and the common electrode 216 is electrically connected to the second electrode contact 215. The transparent conductive layer 240 can be in contact with the common electrode 216 of the peripheral area. The common electrode 216 is connected. For example, the transparent conductive layer 240 can simultaneously cover the multiple micro-light-emitting diodes in the light-emitting area and the common electrode in the peripheral area. The current can flow from the first electrode contact 214 of the driving substrate 210 into the first electrode of the micro-light-emitting diode 220, pass through the micro-light-emitting diode 220, and then flow out from the second electrode of the micro-light-emitting diode 220. It flows through the transparent conductive layer 240 to the common electrode 216 and finally reaches the second electrode contact 215 to form a driving circuit. The micro-light-emitting diode 220 can emit light and display when current flows through it. By adjusting the current flowing through the micro-light-emitting diode 220 or the turn-on time, the grayscale, brightness, etc. displayed by the micro-light-emitting diode 220 can be adjusted.

[0056] Considering the light emission effect, the transparent conductive layer 240 can use a material with high visible light transmittance, such as indium tin oxide (ITO). The resistance of the material with high visible light transmittance is usually high. The current of the second electrode of the micro-LED 220 is transmitted to the common electrode 216 through the transparent conductive layer 240. The material of the transparent conductive layer 240 (for example, ITO) has a large resistance, and the path lengths of the current of the micro-LEDs 220 at different positions to reach the common electrode 216 are different. For example, referring to FIG3, FIG3 shows a cross-sectional schematic diagram along the BB' direction in FIG2. The current path between the micro-LED 220 close to the common electrode 216 and the common electrode 216 is shorter, while the current path between the micro-LED 220 far from the common electrode 216 and the common electrode 216 is longer. The path lengths of the current loops of the micro-LEDs 220 at different positions are different, and the resistivity of the transparent conductive layer 240 is high, which leads to a certain voltage drop (IR drop) problem. Since the LED display panel uses current to drive the micro-light emitting diodes to emit light, and the micro-light emitting diodes are more sensitive to slight changes in current, small current changes will cause larger brightness changes. The current path between the micro-light emitting diodes close to the common electrode 216 and the common electrode 216 is shorter, the resistance is smaller, and the voltage drop is also smaller. Therefore, the display brightness of these micro-light emitting diodes is less affected. The current path between the micro-light emitting diodes far from the common electrode 216 and the common electrode 216 is longer, the resistance is larger, and the voltage drop is also larger, and the display brightness will become lower, resulting in brightness differences between the micro-light emitting diodes at different positions.

[0057] The current loops of the micro-light-emitting diodes at different positions have different lengths of paths flowing through the transparent conductive layer. The resistivity of the material of the transparent conductive layer is relatively high. Therefore, the resistance of the current loop with a long path flowing through the transparent conductive layer is large, and the resistance of the current loop with a short path flowing through the transparent conductive layer is small. The difference in resistance will cause different current sizes in different loops, and ultimately lead to differences in display brightness.

[0058] In order to improve the above problems, an embodiment of the present application provides another display module, in which a conductive grid is set on the driving substrate. The current of each pixel does not flow to the common electrode through the transparent conductive layer, but can flow to the conductive grid through the transparent conductive layer, and then flow to the second electrode contact through the conductive grid to form a loop. The resistance of the conductive grid is smaller than the resistance of the material of the transparent conductive layer. Such a solution is equivalent to replacing the material of the transparent conductive layer with a higher resistivity in the current loop of the micro-light-emitting diode with the material of the conductive grid, which can reduce the resistance of the current loop of the micro-light-emitting diode and avoid IR drop that affects the imaging quality.

[0059] 4 and 5 , FIG4 shows a schematic structural diagram of a display module 300 provided in an embodiment of the present application, and FIG5 shows a cross-sectional view taken along the line BB′ in FIG4 . The display module 300 includes a driving substrate 310, and a conductive grid 330, a transparent conductive layer 340, and a plurality of micro-light-emitting diodes 320 arranged on the driving substrate 310. The driving substrate 310 includes a light-emitting area and a peripheral area outside the light-emitting area. The light-emitting area is provided with multiple first electrode contacts 314, and the peripheral area is provided with second electrode contacts 315. The driving substrate is also provided with a common electrode 316 electrically connected to the second electrode contact 314. Multiple micro-light-emitting diodes 320 are arranged in the light-emitting area. The multiple micro-light-emitting diodes 320 correspond one-to-one to the multiple electrode contacts 314. The micro-light-emitting diodes 320 include a first electrode and a second electrode. In this embodiment, the first electrode is an electrode facing the driving substrate 310, and the second electrode is an electrode away from the driving substrate 310. The first electrode of the micro-light-emitting diode 320 is in contact with the electrode contact 314 corresponding to the micro-light-emitting diode 320 to form an electrical connection.

[0060] The conductive grid 330 is set on the driving substrate 310. The conductive grid 330 is a grid formed by cross-connecting multiple conductive grid lines. The conductive grid 330 includes multiple grids, and the micro-light-emitting diodes 320 correspond to the grids. The micro-light-emitting diodes 320 can be set on the area of ​​the driving substrate 310 defined by the grids. The conductive grid 330 located in the peripheral area is in contact with and electrically connected to the common electrode 316.

[0061] The transparent conductive layer 340 covers the conductive grid 330 located in the light-emitting area, the transparent conductive layer 340 is electrically connected to the conductive grid 330, the second electrode of the micro-light-emitting diode 320 is in contact with the transparent conductive layer 340 (or it can be considered that the part of the transparent conductive layer 340 in contact with the micro-light-emitting diode forms the second electrode of the micro-light-emitting diode 320), and the projection of the transparent conductive layer 340 on the driving substrate 310 covers the light-emitting area. This ensures that the transparent conductive layer 340 is electrically connected to all the micro-light-emitting diodes 320, and the transparent conductive layer 340 is electrically connected to the conductive grid 330, that is, in the embodiment of the present application, the conductive grid 330 is electrically connected to the common electrode 316, and the second electrode of the micro-light-emitting diode 220 can be electrically connected to the conductive grid 330 through the transparent conductive layer 340, that is, electrically connected to the common electrode 316

[0062] In some embodiments, the drive substrate 310 may include a substrate 311, a drive circuit layer 312, and a protective layer 313, which are arranged in sequence. The drive circuit layer 312 may include multiple drive circuits or drive units for controlling the active driving of the Micro LED. The drive circuits may generally include complementary metal oxide semiconductor (CMOS) devices or TFT devices. A plurality of first electrode contacts 314 and second electrode contacts 315 are provided on the surface of the protective layer 313. The first electrode contacts 314 and the second electrode contacts 315 are connected to the drive circuit layer 312 through vias in the protective layer 313. For example, the first electrode contacts 314 may be anode contacts, and the second electrode contacts 315 may be cathode contacts. A common electrode 316 is also provided on the drive substrate 310, corresponding to the position of the second electrode contacts 315. The common electrode 316 is electrically connected to the second electrode contacts. The material of the substrate 311 may be a semiconductor material such as silicon, silicon carbide, gallium nitride, germanium, gallium arsenide, indium phosphide, or a non-conductive material such as glass, plastic, or sapphire wafer.

[0063] The driving substrate 310 can provide driving current for each micro-LED 320. The current flows from the first electrode contact 314 of the driving substrate 310 into the first electrode of the micro-LED 320, flows out from the second electrode of the micro-LED 320, and finally reaches the second electrode contact 315 on the driving substrate 310 to form a loop.

[0064] In one possible implementation, please refer to Figure 4, a plurality of pads 350 are also provided on the driving substrate 310, a part of these pads 350 are electrically connected to the driving circuit in the driving circuit layer 312, and are used to provide power signals, data signals, etc. to the driving circuit, and another part of the pads 350 can be electrically connected to the second electrode contact 315 on the driving substrate 310. The first electrode of the micro-light-emitting diode 320 is electrically connected to the first electrode contact 314 on the driving substrate 310, that is, it is electrically connected to the driving circuit in the driving circuit layer 312. The second electrode of the micro-light-emitting diode 320 is electrically connected to the common electrode 316, that is, it is electrically connected to the second electrode contact 315. In one possible implementation, the second electrode contact 315 can be a cathode and the first electrode contact 314 can be an anode. When the micro-light-emitting diode 320 forms a loop with the first electrode contact 314 and the common electrode 316 (or the second electrode contact 315), the cathode current can be injected into the micro-light-emitting diode 320 from the common electrode 316 (or the second electrode contact 315) and recombine with the carriers injected into the micro-light-emitting diode 320 by the first electrode contact 314 to emit light.

[0065] In the embodiment of the present application, since a conductive grid 330 is provided on the driving substrate 310, the second electrode of the micro-LED 320 is electrically connected to the conductive grid 330 via the transparent conductive layer 340, and the conductive grid 330 is electrically connected to the common electrode 316. In this way, after the current flows from the second electrode of the micro-LED 320 to the transparent conductive layer 340, it will choose to flow through the conductive grid 330 with lower resistance to the common electrode 316 to form a loop. The conductive grid 330 has good conductivity and low resistance. This can overcome problems such as IR drop caused by the high resistance of the transparent conductive layer 340.

[0066] 6 and 7 , FIG6 shows a schematic diagram of a display module, and FIG7 shows a schematic diagram of another display module. FIG6 shows micro-LED 220-1 and micro-LED 220-2, wherein micro-LED 220-1 is farther from common electrode 216, while micro-LED 220-2 is closer to common electrode 216. FIG7 shows micro-LED 320-1 and micro-LED 320-2, wherein micro-LED 320-1 is farther from common electrode 316, while micro-LED 320-2 is closer to common electrode 316.

[0067] In the absence of a conductive grid, for example, in conjunction with Figures a and b in Figure 6 , the path of the current loop of the micro-light-emitting diodes (220-1, 220-2) is as follows: it flows into the first electrodes of the micro-light-emitting diodes (220-1, 220-2) through the first electrode contacts 214, flows out to the transparent conductive layer 240 through the second electrodes of the micro-light-emitting diodes (220-1, 220-2), and flows to the common electrode 216 through the transparent conductive layer 240 to form a loop.

[0068] In the case of providing a conductive grid, in combination with Figures a and b in Figure 7 , the path of the current loop of the micro-LEDs (320-1, 320-2) is as follows: it flows into the first electrode of the micro-LEDs (320-1, 320-2) through the first electrode contact 314, flows out to the transparent conductive layer 340 through the second electrode of the micro-LEDs (320-1, 320-2), flows to the nearest conductive grid 330 through the transparent conductive layer 340, and flows to the common electrode 316 through the conductive grid 330 to form a loop.

[0069] From this, it can be seen, combined with Figure 6, that when the conductive grid is not set, the transparent conductive layer occupies a larger part of the current path of the micro-LED, so the loop resistance is relatively large; after the conductive grid is set, the transparent conductive layer occupies only a small part of the current path of the micro-LED, and the conductive grid occupies a larger part, so the resistance is smaller, which can avoid problems such as display quality degradation caused by IR Drop.

[0070] In addition, for the micro-LEDs 320-1 and 320-2 at different positions, although the lengths of their current paths are different due to their different distances from the common electrode 316, the difference in the length of the current path is mainly reflected in the portion occupied by the conductive grid. The conductive grid is made of conductive metal material with low resistance, so such a difference will not result in a significant resistance change. When the mesh pitch of the conductive grid is close, for the micro-LEDs 320-1 and 320-2 at different positions, the portion of their current paths occupied by the transparent conductive layer 340 is similar, that is, the distance from the second electrode of the micro-LED to the nearest conductive grid. This makes the resistance of the current loops of the micro-LEDs at different positions close, which can avoid differences in display brightness.

[0071] In some embodiments of the present application, the resistivity of the material of the conductive grid is lower than the resistivity of the material of the transparent conductive layer. For example, the conductive grid can be made of a conductive metal material, which can include a single layer of metal, a stacked metal, or a stacked structure of a dielectric and a metal, such as copper (Cu), aluminum (Al), tungsten (W), titanium nitride (TiN), tantalum nitride (TaN), titanium tungsten alloy (TiW), a stacked structure of titanium tungsten alloy-aluminum-titanium tungsten alloy (TiW / Al / TiW), a stacked structure of titanium nitride-aluminum-titanium nitride (TiN / Al / TiN), a stacked structure of titanium tungsten alloy-aluminum-titanium nitride (TiW / Al / TiN), a stacked structure of titanium tungsten alloy-tungsten-titanium nitride (TiW / W / TiN), and the like.

[0072] In some embodiments of the present application, the conductive grid 330 can be disposed on the driver substrate 310 and electrically connected to the common electrode 316. The conductive grid 330 is electrically connected to the second electrode contact 315 via the common electrode 316. In other possible implementations of the present application, for example, referring to FIG8 , the conductive grid 330 can be electrically connected to the second electrode contact 315 via internal wiring of the driver substrate 310. Furthermore, in some other embodiments of the present application, the conductive grid 330 can be electrically connected to the second electrode contact 315 in other ways to reduce the voltage drop caused by the transparent conductive layer in the drive circuit of the micro-LED.

[0073] Because Micro LEDs are self-luminous devices, their light emission shape is a Lambertian body, as shown in Figure 9. This means that the brightness of light emitted by the Micro LED in all directions is the same, which can cause optical crosstalk between pixels. To avoid this problem, the embodiments of the present application can use a conductive grid to define the light emission direction of each Micro LED, thereby preventing optical crosstalk between pixels.

[0074] In some embodiments of the present application, the conductive mesh may be an opaque conductive mesh. In conjunction with FIG10 , the height of the conductive mesh in a direction perpendicular to the driving substrate is no less than the height of the micro-LEDs. For example, in conjunction with FIG10 a, the conductive mesh 330 and the micro-LEDs 320 each include an upper surface and a lower surface. The lower surface 330B of the conductive mesh 330 is no higher than the lower surface 320B of the micro-LEDs 320. Alternatively, the distance from the lower surface 330B of the conductive mesh 330 to the driving substrate 310 is less than or equal to the distance from the lower surface 320B of the micro-LEDs 320 to the driving substrate 310. Furthermore, the upper surface 330A of the conductive mesh 330 is no lower than the upper surface 320A of the micro-LEDs 320. Alternatively, the distance from the upper surface 330A of the conductive mesh 330 to the driving substrate 310 is greater than or equal to the distance from the upper surface 330A of the conductive mesh 330 to the driving substrate 310. In other words, the lowest point of the conductive grid 330 in the direction perpendicular to the driving substrate is not higher than the lowest point of the micro-LED 320, and the highest point of the conductive grid 330 in the direction perpendicular to the driving substrate is not lower than the highest point of the micro-LED 320. Combined with Figure b in Figure 10, this setting can use the conductive grid 330 to block the light emitted by the micro-LED 320 from scattering to adjacent micro-LEDs 320, thereby avoiding light crosstalk between different pixels.

[0075] In some embodiments of the present application, the height L1 of the conductive grid 330 is no less than the height L2 of the micro-LEDs 320, and the lowest point of the conductive grid 330 in a direction perpendicular to the driving substrate is lower than the lowest point of the micro-LEDs 320. This prevents light emitted by the micro-LEDs 320 from leaking from the bottom of the micro-LEDs 320 and causing crosstalk. The highest point of the conductive grid 330 in a direction perpendicular to the driving substrate is higher than the highest point of the micro-LEDs 320, preventing light from the top of the micro-LEDs 320 from generating crosstalk in the horizontal direction.

[0076] In addition, in combination with Figure b in Figure 10, the conductive grid 330 can also have a certain reflective effect on the light emitted by the micro-LED 320, which can gather and / or collimate the light emitted by the micro-LED 320, thereby improving the overall brightness of the display module.

[0077] In some embodiments of the present application, the height L1 of the conductive grid 330 in the direction perpendicular to the driving substrate is 1 to 2 times the height L2 of the micro-light-emitting diode 320. When the height L1 of the conductive grid 330 is the same as the height L2 of the micro-light-emitting diode 320, in order to ensure the anti-crosstalk effect, it is necessary to make the upper surface 330A of the conductive grid 330 flush with the upper surface 320A of the micro-light-emitting diode 320, and make the lower surface 330B of the conductive grid 330 flush with the lower surface 320B of the micro-light-emitting diode 320.

[0078] In some embodiments of the present application, the conductive grid is a conductive grid formed by the intersection of multiple grid lines, and the conductive grid includes multiple grids. One or more micro-LEDs can be arranged in the area of ​​the driver substrate defined by each grid. Here, whether it is a micro-LED or multiple micro-LEDs, it refers to the smallest unit of an LED pixel. For example, in some cases, the display module is a monochrome display module, and one micro-LED can constitute a pixel. In this case, one micro-LED can be arranged in the area defined by the grid of the conductive grid, and this micro-LED is connected to the conductive grid via a transparent conductive layer. In other cases, the display module is a color display module, and multiple micro-LEDs are combined to form a pixel. In this case, multiple micro-LEDs can be arranged in the area defined by the grid of the conductive grid, and these micro-LEDs are electrically connected to the conductive grid via a transparent conductive layer. For example, if a pixel includes two red sub-pixels, one green sub-pixel, and one blue sub-pixel, then four micro-LEDs, namely two red micro-LEDs, one blue micro-LED, and one green micro-LED, can be arranged in the grid holes of the conductive grid.

[0079] In some embodiments of the present application, the conductive grid includes a plurality of grid holes, as shown in Figure b of Figure 10 , the side walls of the grid holes may be perpendicular to the driving substrate, or, as shown in Figure c of Figure 10 , the side walls of the grid may also be at a certain angle to the driving substrate, for example, the side walls of the grid holes are arranged at an obtuse angle to the driving substrate, so that the light emitted by the micro light-emitting diode can be reflected multiple times on the inner wall of the grid hole and finally emitted through the opening of the grid hole, which can avoid light crosstalk between different pixels and improve the luminous brightness.

[0080] In addition, referring to FIG11 , the shape of the conductive grid may include regular shapes such as triangles, quadrilaterals, hexagons, octagons, and circles, or irregular shapes, which may be adjusted accordingly according to the arrangement of the micro-LEDs.

[0081] 12 , the conductive grid 330 may be a conductive grid formed by the intersection of multiple conductive metal wires. In the embodiment of the present application, the width W of the grid lines of the conductive grid 330 is 10 nm to 1000 nm. Since the pitch between two adjacent micro-LEDs in Micro LEDs is often fixed, and the larger the area of ​​the micro-LEDs, the higher the brightness of the light, in this case, the larger the size of a single micro-LED, the smaller the distance between the boundaries of the two adjacent micro-LEDs, and the smaller the size of the conductive grid that can be set. In the embodiment of the present application, the width W of the grid lines of the conductive grid may be 500 nm.

[0082] In some embodiments, referring to FIG5 , a micro-LED 320 includes an ohmic contact layer 324, a first semiconductor layer 321, a light-emitting layer 322, and a second semiconductor layer 323, which are sequentially stacked. The first semiconductor layer 321 is located on a side close to the driver substrate 310, and the second semiconductor layer 323 is located on a side facing away from the driver substrate 310. In some embodiments of the present application, a bonding layer 325 is further provided between the first semiconductor layer 321 and the driver substrate 310, and the micro-LED 320 can be adhered or bonded to the driver substrate 310 via the bonding layer 325.

[0083] The first semiconductor layer 321 may be P-type doped or N-type doped in a semiconductor material (such as gallium nitride) so that the first semiconductor layer 321 can provide holes or electrons. The second semiconductor layer 323 may be N-type doped or P-type doped in a semiconductor material (such as gallium nitride) so that the second semiconductor layer 323 can provide electrons or holes.

[0084] The first semiconductor layer 321 and the second semiconductor layer 323 are located on both sides of the light emitting layer 322 in a direction perpendicular to the driving substrate 310, and the doping types of the two semiconductor layers are opposite. If the first semiconductor layer 321 is N-type doped, the second semiconductor layer 323 is P-type doped; if the first semiconductor layer 321 is P-type doped, the second semiconductor layer 323 is N-type doped.

[0085] The micro-light-emitting diode 320 may also include an ohmic contact layer 324 in contact with the first semiconductor layer 321. The ohmic contact layer 324 may improve the conductivity between the first semiconductor layer 321 and the driving substrate 310, and in the embodiment of the present application, the ohmic contact layer 324 may form the first electrode of the micro-light-emitting diode 320; the micro-light-emitting diode 320 also includes a second electrode opposite to the first electrode. In one possible implementation, a conductive contact layer (not shown) may be provided on the second semiconductor layer 323 as the second electrode of the micro-light-emitting diode 320, or in the embodiment of the present application, a transparent conductive layer 340 in contact with the second semiconductor layer 323 may be used as the second electrode of the micro-light-emitting diode 320, and multiple micro-light-emitting diodes 320 may share the same second electrode.

[0086] In some embodiments of the present application, a bonding layer 325 is further provided between the ohmic contact layer 324 and the driving substrate 310 . The bonding layer 325 is used to bond the micro light emitting diode 320 to the driving substrate 310 .

[0087] In this embodiment, the first semiconductor layer 321 is P-type doped, and the second semiconductor layer 323 is N-type doped. Based on this, the first electrode of the micro-LED 320 can be an anode, and an anode voltage is applied to the first semiconductor layer 321; the second electrode of the micro-LED 320 can be a cathode, and a cathode voltage is applied to the second semiconductor layer 323.

[0088] In some cases, the micro-LEDs 320 are also referred to as micro-LED mesas. The cross-section of each micro-LED 320 can be trapezoidal, meaning the sidewalls of the micro-LED 320 can be inclined, and the angle between the sidewalls and the top surface of the micro-LED 320 can be obtuse, thereby enhancing the light-collecting effect of the micro-LED. Alternatively, in some possible implementations, the micro-LEDs can be columnar, in which case the angle between the sidewalls and the top surface of the micro-LED is a right angle.

[0089] In some embodiments, a passivation layer can be provided on the sidewalls of the micro-LEDs to prevent etching damage during the fabrication process. The passivation layer is typically made of materials such as aluminum oxide and silicon oxide. A filler layer is provided between adjacent micro-LEDs and on the surface of the driver substrate.

[0090] In combination with Figures 13 and 14, Figure 14 shows a cross-sectional view along the BB' direction in Figure 13. The conductive grid 330 is arranged in the light-emitting area and the peripheral area of ​​the driving substrate 310. Micro-light-emitting diodes 320 are arranged in the grid holes in the light-emitting area, and a height control layer 360 is arranged in the grid holes in the peripheral area. The material of the height control layer 360 has a different removal rate from the material of the micro-light-emitting diodes 320, the material of the filling layer, etc. The height control layer 360 is used to control the table height of the micro-light-emitting diodes 320. For example, the upper surface of the micro-light-emitting diodes 320 is flush with the height of the upper surface of the height control layer 360, or it can be considered that the distance between the upper surface of the height control layer and the surface of the driving substrate 310 is the height of the micro-light-emitting diodes 320.

[0091] In the display module 200 provided in the embodiment of the present application, when no height control layer is provided, the height of the micro-LED can only be controlled based on experience when the wafer surface is flattened. The table height cannot be accurately controlled during the flattening process, and excessive flattening may cause the height of the micro-LED to be too low. In the display module 300 provided in the embodiment of the present application, a filling layer is provided between adjacent micro-LEDs 320, a filling layer is provided in the peripheral area outside the light-emitting area, and a height control layer 360 is provided above the filling. In this way, when the wafer surface is flattened using processes such as CMP, since the material of the height control layer 360 has different removal rates from the material of the micro-LED 320 and the material of the filling layer, the height of the wafer can be stopped at the upper surface of the height control layer 360 during the flattening process, thereby achieving precise control of the height of the micro-LED 320.

[0092] In some other possible implementations, please refer to Figure 15, the display module 300 also includes a lens layer 370, which is arranged on the transparent conductive layer 340. The lens layer 370 includes a plurality of lenses, and the plurality of lenses correspond one-to-one to the plurality of micro-LEDs. For example, lens 370-1 corresponds to micro-LED 320-1, lens 370-2 corresponds to micro-LED 320-2, and lens 370-3 corresponds to micro-LED 320-3. In some embodiments of the present application, the central axis of the lens can be located on the same straight line as the central axis of the micro-LED, so that the lens can be used to collimate the light emitted by the micro-LED, thereby improving the luminous efficiency and luminous uniformity of the display module. In other embodiments, the central axis of the lens can be misaligned with the central axis of the micro-LED or can have a certain angle with the central axis of the micro-LED, so that the light emitting direction of the micro-LED can be adjusted.

[0093] In addition, the embodiment of the present application further provides a method for preparing a display module. Referring to FIG. 16 , the method includes:

[0094] S41: A plurality of micro light emitting diodes are formed on a driving substrate, wherein the micro light emitting diodes include a first electrode and a second electrode that are arranged opposite to each other, and the driving substrate includes a plurality of first electrode contacts and a second electrode contact. The plurality of micro light emitting diodes correspond one-to-one to the plurality of first electrode contacts, and the first electrodes of the micro light emitting diodes are in contact with the first electrode contacts corresponding to the micro light emitting diodes.

[0095] Multiple micro-LEDs correspond one-to-one to multiple first electrode contacts. The first electrodes of the micro-LEDs contact the corresponding first electrode contacts to form an electrical connection. Current signals can be injected into the micro-LEDs through the first electrode contacts to make the micro-LEDs emit light.

[0096] S42: forming a height control layer on the driving substrate, wherein the upper surface of the micro light emitting diode is flush with the upper surface of the height control layer.

[0097] The removal rate of the material of the height control layer is different from the removal rate of the material of the micro-light-emitting diode and the material of the dielectric filling layer. The embodiment of the present application uses the height control layer to accurately control the height of the micro-light-emitting diode in the light-emitting area. For example, the height of the wafer can be made to stay at the upper surface of the height control layer, and the upper surface of the micro-light-emitting diode is flush with the upper surface of the height control layer, thereby achieving precise control of the height of the micro-light-emitting diode, thereby improving the pixel light output efficiency.

[0098] S43: forming a common electrode and a conductive grid on the driving substrate, wherein the conductive grid contacts the common electrode and includes a plurality of grids, and the micro light emitting diodes correspond to the grids, and the micro light emitting diodes are located in areas defined by the corresponding grids.

[0099] S44: forming a transparent conductive layer, wherein the transparent conductive layer covers the plurality of micro-light emitting diodes and the conductive grid, and the second electrodes of the micro-light emitting diodes are electrically connected to the conductive grid through the transparent conductive layer.

[0100] In the embodiment of the present application, the height of the micro-LEDs is precisely controlled by utilizing the different removal rates of the material of the height control layer, the material of the micro-LEDs, and the material of the dielectric filling layer. Based on FIG. 16 and in combination with FIG. 17 , S42 includes:

[0101] S421: forming a first dielectric filling layer on the surface of the wafer after the micro-light emitting diodes are formed.

[0102] S422: forming a height control layer on the first dielectric filling layer.

[0103] S423: forming a second dielectric filling layer on the height control layer.

[0104] S424: After forming the second dielectric filling layer, the wafer is flattened so that the surface height of the wafer stops at the surface of the height control layer, and the upper surface of the micro-light-emitting diode is flush with the upper surface of the height control layer, wherein the material of the height control layer has different removal rates from the material of the micro-light-emitting diode and the materials of the first dielectric filling layer and the second dielectric filling layer.

[0105] The material of the height control layer has different removal rates from the material of the micro-light-emitting diode and the materials of the first dielectric filling layer and the second dielectric filling layer. In this way, when the wafer is flattened, the height of the wafer can be stopped at the surface of the height control layer, so that the upper surface of the micro-light-emitting diode is flush with the upper surface of the height control layer.

[0106] In some embodiments of the present application, based on FIG. 16 , referring to FIG. 18 , S43 includes:

[0107] S431: forming a grid-like groove and a common electrode groove on the surface of the wafer, wherein the grid-like groove and the common electrode groove are connected.

[0108] In some embodiments of the present application, the above-mentioned grid-like grooves are formed in the light-emitting area and the peripheral area, and a common electrode groove is formed in the peripheral area, wherein the second electrode contact is exposed at the bottom of the common electrode groove, and the grid-like grooves form a plurality of grids, and the above-mentioned micro light-emitting diodes are arranged in the area defined by the grids in the light-emitting area, and a height control layer is arranged in the area defined by the grids in the peripheral area.

[0109] S432: forming a conductive grid in the grid-shaped grooves and forming a common electrode in the common electrode grooves.

[0110] The second electrode contact is exposed through the bottom of the common electrode groove, so the common electrode formed in the common electrode groove is electrically connected to the second electrode contact, and because the grid-shaped groove is connected to the common electrode groove, after the common electrode is formed in the common electrode groove and the conductive grid is formed in the grid-shaped groove, the conductive grid contacts the common electrode to form an electrical connection. The conductive grid can be formed by conductive metal materials, such as copper (Cu), aluminum (Al), tungsten (W), titanium nitride (TiN), tantalum nitride (TaN), titanium tungsten alloy (TiW), titanium tungsten alloy-aluminum-titanium tungsten alloy stacked structure (TiW / Al / TiW), titanium nitride-aluminum-titanium nitride stacked structure (TiN / Al / TiN), titanium tungsten alloy-aluminum-titanium nitride stacked structure (TiW / Al / TiN), titanium tungsten alloy-tungsten-titanium nitride (TiW / W / TiN) stacked structure, etc.

[0111] The specific process flow involved in the above steps will be introduced below with reference to the accompanying drawings.

[0112] Referring to Figure a in Figure 19, a driving circuit layer 502, a protective layer 503, a bonding layer 504, an ohmic contact layer 505, a first semiconductor layer 506, a light-emitting layer 507 and a second semiconductor layer 508 are formed on a substrate 501, wherein the substrate 501, the driving circuit layer 502 and the protective layer 503 form a driving substrate, the above-mentioned first semiconductor layer 506 can be a P-type semiconductor layer, and the second semiconductor layer 508 can be an N-type semiconductor layer.

[0113] Referring to Figure b in Figure 19, the parts other than the light-emitting pixels are removed to form a plurality of micro-light-emitting diodes or micro-light-emitting diode mesas. In some embodiments of the present application, the driving substrate includes a light-emitting area and a peripheral area outside the light-emitting area, wherein the light-emitting area is provided with a plurality of first electrode contacts, such as the first electrode contact 500A shown in Figure b in Figure 19, and the peripheral area is provided with second electrode contacts and pad contacts, such as the second electrode contact 500B and the pad contact 500C shown in Figure b in Figure 19. The epitaxial structure above the first electrode contact can be retained, and the other structures can be removed by dry etching and retained on the surface of the driving substrate. In this way, a plurality of micro-light-emitting diodes corresponding to the first electrode contacts can be formed, and the ohmic contact layer 505 can form the first electrode of the micro-light-emitting diode. The first electrode of the micro-light-emitting diode contacts with the first electrode contact corresponding to the micro-light-emitting diode to form an electrical connection.

[0114] Referring to Figure c in FIG. 19 , a passivation layer 509 is deposited on the surface of the driving substrate and the micro-LEDs. For example, the material of the passivation layer 509 may be aluminum oxide, silicon oxide, or the like.

[0115] Referring to FIG. 19 d , a first dielectric filling layer 510 is deposited on the passivation layer 509 . The material of the first dielectric filling layer 510 may be silicon oxide or other materials.

[0116] Referring to FIG. 20 a, a height control layer 511 is deposited on the first dielectric filling layer 510. The material of the height control layer 511 can be a material having a different removal rate than that of the dielectric filling layer and the materials of the micro-LEDs. For example, the material of the height control layer 511 can be silicon nitride. The height control layer 511 is used to control the height of the micro-LEDs. For example, in the embodiment of the present application, the distance between the upper surface of the height control layer 511 and the surface of the drive substrate is the height of the micro-LEDs.

[0117] Alternatively, referring to a′ in FIG. 20 , the dielectric filling layer may not be provided between the height control layer 511 and the driving substrate, and the height control layer 511 may be directly deposited on the passivation layer 509 .

[0118] 20 b , a second dielectric filling layer 512 is formed on the height control layer 511 . The material of the second dielectric filling layer 512 may be the same as that of the first dielectric filling layer 510 . For example, the material of the second dielectric filling layer 512 may be silicon oxide or the like.

[0119] Referring to Figure c in Figure 20, the wafer surface is flattened, for example, using a CMP surface flattening process. Since the removal rates of the material of the height control layer 511 and the dielectric filling layer and the micro-LED material are different, the structure on the surface of the micro-LED can be removed, so that the wafer surface height stops at the surface of the height control layer 511, thereby controlling the height of the micro-LED. At this time, the upper surface of the micro-LED is flush with the upper surface of the height control layer 511, and the distance between the upper surface of the height control layer 511 and the surface of the driving substrate is the height of the micro-LED.

[0120] Referring to Figure 20 (d), a grid of grooves 513 and common electrode grooves 514 are formed on the wafer surface. Second electrode contacts can be connected via the bottom surface of the common electrode grooves 514. Micro-LEDs are positioned within the area defined by the grids formed by the grid-like grooves in the light-emitting region, while the aforementioned first dielectric filling layer 510 and height control layer 511 are positioned within the area defined by the grids formed by the grid-like grooves in the peripheral region. In some embodiments, pad grooves 515 are also formed by etching simultaneously with the formation of the pad contacts.

[0121] Referring to FIG. 21 a, a conductive grid 516 is formed in the grid-shaped grooves 513, a common electrode 519 is formed in the common electrode grooves 514, and the common electrode 519 is electrically connected to the second electrode contact. A pad 520 is formed in the pad grooves 515, and the conductive grid 516 is electrically connected to the common electrode 519. The height of the conductive grid 516 is not less than the height of the micro-LED.

[0122] Referring to Figure b in Figure 21, a transparent conductive layer 521 is prepared above the light-emitting area. The projection of the transparent conductive layer 521 on the driving substrate covers the light-emitting area. The transparent conductive layer 521 is in contact with the second electrode of the micro-light-emitting diode, or it can be considered that the part of the transparent conductive layer 521 in contact with the micro-light-emitting diode constitutes the second electrode of the micro-light-emitting diode. The transparent conductive layer 521 is also electrically connected to the conductive grid of the light-emitting area, so that the second electrode of the micro-light-emitting diode can be electrically connected to the conductive grid and the common electrode through the transparent conductive layer.

[0123] Referring to Figure c in Figure 21, a lens layer 522 can also be prepared on the transparent conductive layer 521. The lens layer 522 includes multiple lenses, and the multiple lenses correspond one-to-one to the multiple micro-light-emitting diodes. The axis of the lens can be on the same straight line as the axis of the micro-light-emitting diode, or can be at a certain angle.

[0124] Alternatively, it is also possible to combine FIG. 20 a′ and FIG. 21 d . FIG. 21 d shows a display module in which no dielectric filling layer is provided between the height control layer 511 and the driving substrate.

[0125] As shown in the process flow diagrams of Figures 19 to 21, the method provided by the present embodiment first forms a plurality of micro-LEDs on a driver substrate, then sequentially forms a first dielectric filling layer 510, a height control layer 511, and a second dielectric filling layer 512. By utilizing the different removal rates of the height control layer 511 and the dielectric filling layer, the wafer surface can be stopped at the surface of the height control layer 511, thereby precisely controlling the height of the micro-LEDs. After the height of the micro-LEDs is controlled, a conductive grid 516 is formed by slotting, and finally a transparent conductive layer 521 is formed on the light-emitting area. The provision of the conductive grid 516 can, on the one hand, change the current path of the micro-LEDs, so that the current originally flowing through the transparent conductive layer 521 to the common electrode 519 flows through the conductive grid 516 to the common electrode 519, thereby reducing resistance and preventing IR drop from affecting the display effect. On the other hand, the conductive grid 516 can be an opaque grid, and the micro-LEDs can be placed in the grid holes formed by the conductive grid 516. The conductive grid 516 can block the light emitted by different micro-LEDs, preventing crosstalk between the light emitted by different micro-LEDs.

[0126] The present application also provides an electronic device, comprising a housing and a display module as described in the aforementioned examples, wherein the display module can be mounted on the housing. For example, the electronic device can be a mobile phone, personal computer (PC), tablet computer (pad), smart wearable product (e.g., smart watch, smart bracelet), virtual reality (VR) terminal device, augmented reality (AR) terminal device, vehicle-mounted terminal, display, or other electronic device mentioned in the aforementioned examples.

[0127] In the description of this specification, specific features, structures, materials or characteristics may be combined in an appropriate manner in any one or more embodiments or examples.

[0128] The above description is merely a specific embodiment of the present application, but the scope of protection of the present application is not limited thereto. Any changes or substitutions that can be easily conceived by a person skilled in the art within the technical scope disclosed in this application should be included in the scope of protection of this application. Therefore, the scope of protection of this application should be based on the scope of protection of the claims.

Claims

1. A display module, characterized in that: The display module comprises: A driving substrate, comprising a plurality of first electrode contacts and second electrode contacts, wherein the first electrode contacts and the second electrode contacts are used to form a driving circuit with the micro light emitting diode; A plurality of micro-LEDs, each of which comprises a first electrode and a second electrode, wherein the plurality of micro-LEDs correspond to the plurality of first electrode contacts one by one, and the first electrode of the micro-LED is electrically connected to the first electrode contact; A conductive grid, the conductive grid comprising a plurality of grids, the conductive grid being electrically connected to the second electrode contact; A transparent conductive layer, wherein the transparent conductive layer covers the plurality of micro-LEDs and the conductive grid, the second electrode of the micro-LED is electrically connected to the conductive grid through the transparent conductive layer, and the resistivity of the material of the conductive grid is less than the resistivity of the material of the transparent conductive layer.

2. The display module according to claim 1, characterized in that: A common electrode is also provided on the driving substrate, and the conductive grid is electrically connected to the second electrode contact through the common electrode.

3. The display module according to claim 1, characterized in that: The conductive grid is electrically connected to the second electrode contact through an internal circuit of the driving substrate.

4. The display module according to any one of claims 1 to 3, characterized in that: A height control layer is also provided on the driving substrate, and the upper surface of the micro light emitting diode is flush with the upper surface of the height control layer.

5. The display module according to claim 4, characterized in that: The display module also includes a dielectric filling layer, which is respectively arranged between adjacent micro-light emitting diodes and between the height control layer and the driving substrate. The material of the height control layer has different removal rates from the material of the dielectric filling layer and the material of the micro-light emitting diodes.

6. The display module according to any one of claims 1 to 5, characterized in that: A plurality of the micro light emitting diodes are arranged in the area defined by each grid.

7. The display module according to any one of claims 1 to 5, characterized in that: One of the micro light emitting diodes is arranged in an area defined by each grid.

8. The display module according to any one of claims 1 to 7, characterized in that: The width of the grid lines of the conductive grid is 10 nm to 1000 nm.

9. The display module according to any one of claims 1 to 8, characterized in that: The conductive grid includes a lower surface facing the driving substrate and an upper surface facing away from the driving substrate in a direction perpendicular to the driving substrate, and the micro light emitting diode includes a lower surface facing the driving substrate and an upper surface facing away from the driving substrate in a direction perpendicular to the driving substrate; The distance between the lower surface of the conductive grid and the driving substrate is less than or equal to the distance between the lower surface of the micro-LED and the driving substrate; The distance between the upper surface of the conductive grid and the driving substrate is greater than or equal to the distance between the upper surface of the micro light emitting diode and the driving substrate.

10. The display module according to any one of claims 1 to 9, characterized in that: The height of the conductive grid in a direction perpendicular to the driving substrate is 1 to 2 times the height of the micro light emitting diode in a direction perpendicular to the driving substrate.

11. The display module according to any one of claims 1 to 9, characterized in that: The display module further comprises a lens layer, which is arranged on the transparent conductive layer and is used for collimating the light emitted by the micro light emitting diode.

12. A method for preparing a display module, characterized in that: The method comprises: A plurality of micro-LEDs are formed on a driving substrate, wherein the micro-LEDs include first electrodes and second electrodes that are arranged opposite to each other, the driving substrate includes a plurality of first electrode contacts and a second electrode contact, the plurality of micro-LEDs correspond to the plurality of first electrode contacts one by one, and the first electrodes of the micro-LEDs are in contact with the first electrode contacts corresponding to the micro-LEDs; A common electrode and a conductive grid are formed on the driving substrate, wherein the common electrode is electrically connected to the second electrode contact, the conductive grid is electrically connected to the common electrode, the conductive grid includes a plurality of grids, the micro-LEDs correspond to the grids, and the micro-LEDs are located in an area defined by the corresponding grids; A transparent conductive layer is formed, wherein the transparent conductive layer covers the plurality of micro-light emitting diodes and the conductive grid, and the second electrodes of the micro-light emitting diodes are electrically connected to the conductive grid through the transparent conductive layer.

13. The method according to claim 12, characterized in that Before forming a common electrode and a conductive grid on the driving substrate, the method further includes: A height control layer is formed on the driving substrate, and an upper surface of the micro light emitting diode is flush with an upper surface of the height control layer.

14. The method according to claim 13, characterized in that The height control layer is formed on the driving substrate, and the upper surface of the micro light emitting diode is flush with the upper surface of the height control layer, comprising: forming a first dielectric filling layer on the surface of the wafer after the micro-light emitting diode is formed; forming the height control layer on the first dielectric filling layer; forming a second dielectric filling layer on the height control layer; The wafer after forming the second dielectric filling layer is planarized so that the surface height of the wafer stops at the surface of the height control layer, and the upper surface of the micro-light-emitting diode is flush with the upper surface of the height control layer, wherein the material of the height control layer has different removal rates from the material of the micro-light-emitting diode and the materials of the first dielectric filling layer and the second dielectric filling layer.

15. The method according to claim 13 or 14, characterized in that A common electrode and a conductive grid are formed on the driving substrate, wherein the conductive grid contacts the common electrode, comprising: Forming a grid-shaped groove and a common electrode groove on the surface of the wafer after the height control layer is formed, wherein the grid-shaped groove and the common electrode groove are connected; The conductive grid is formed in the grid-shaped groove, and the common electrode is formed in the common electrode groove.

16. An electronic device, characterized in that: The invention comprises a housing and a display module as claimed in any one of claims 1 to 11, wherein the display module is mounted on the housing.

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